Citation
Heme Oxygenase-1 Regulates Ccr2/mcp-1 Axis and Granuloma Formation in a Mouse Model of Nontuberculous Mycobacterial Infection.

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Title:
Heme Oxygenase-1 Regulates Ccr2/mcp-1 Axis and Granuloma Formation in a Mouse Model of Nontuberculous Mycobacterial Infection.
Creator:
Regev, Doron
Place of Publication:
[Gainesville, Fla.]
Florida
Publisher:
University of Florida
Publication Date:
Language:
english
Physical Description:
1 online resource (65 p.)

Thesis/Dissertation Information

Degree:
Master's ( M.S.)
Degree Grantor:
University of Florida
Degree Disciplines:
Medical Sciences
Medicine
Committee Chair:
Antony, Veena
Committee Members:
Baker, Henry V.
Ramphal, Reuben
Graduation Date:
8/8/2009

Subjects

Subjects / Keywords:
Cells ( jstor )
Chemokines ( jstor )
Cytokines ( jstor )
Diseases ( jstor )
Granuloma ( jstor )
Infections ( jstor )
Lungs ( jstor )
Macrophages ( jstor )
Magnification ( jstor )
Receptors ( jstor )
Medicine -- Dissertations, Academic -- UF
granuloma, heme, mycobacterium
Genre:
bibliography ( marcgt )
theses ( marcgt )
government publication (state, provincial, terriorial, dependent) ( marcgt )
born-digital ( sobekcm )
Electronic Thesis or Dissertation
Medical Sciences thesis, M.S.

Notes

Abstract:
Non Tuberculous Mycobacterial (NTM) infections are a major cause of disease in animals and humans around the world and have become an increasing source of infection among patients with HIV and AIDS. Recently, there has been an increase in NTM infections in immunocompetent patients, especially in the Southeastern United states. A hallmark of NTM infection is the formation of granulomas which are a conglomeration of the invading pathogen and host inflammatory cells including macrophages, T-cells, B-cells and dendritic cells. Granulomas can contain the pathogen and protect the host from further dissemination of the infection. Heme Oxygenase-1 (HO-1) is a cytoprotective enzyme which breaks down heme. HO-1 is induced by oxidative stress, bacterial infection and many pro-inflammatory cytokines and has been shown to be up-regulated in granulomas and infected tissue. Monocyte Chemotactic Protein-1 (MCP-1) along with its receptor Chemokine Receptor2 (CCR2), are responsible for the recruitment of monocytes from peripheral blood to the site of infection. Our hypothesis is that HO-1 plays a role in the formation of organized (tight) granulomas by regulating the expression of CCR2 and MCP-1 in monocytes and coordinating cellular recruitment form peripheral blood to the site of infection. We have developed a mouse model of Mycobacterium avium infection in both HO-1 +/+ and HO-1 -/- mice to test whether the lack of HO-1 expression results in the formation of unorganized (loose) granulomas and to test whether HO-1 regulates MCP-1 and CCR2 in this disease model. ( en )
General Note:
In the series University of Florida Digital Collections.
General Note:
Includes vita.
Bibliography:
Includes bibliographical references.
Source of Description:
Description based on online resource; title from PDF title page.
Source of Description:
This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Thesis:
Thesis (M.S.)--University of Florida, 2009.
Local:
Adviser: Antony, Veena.
Electronic Access:
RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2010-08-31
Statement of Responsibility:
by Doron Regev.

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UFRGP
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Copyright Regev, Doron. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Embargo Date:
8/31/2010
Classification:
LD1780 2009 ( lcc )

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CHAPTER 5
DISCUSSION

Since the advent of HIV and the AIDS epidemic, NTM infections have become a major

source of disease in the United States and around the world (1). Although NTM typically do not

cause disease in humans, MAC infections have been on the rise in both immune competent

patients as well as the immunocompromised (2). The formation of granuloma is a vital part of

the body's immune defense against invading pathogens. After infection with M. avium, failure to

develop organized granulomas results in the dissemination of the infection and greater injury to

the host. The regulated recruitment of immune cells including monocyte-macrophages, T-cells,

dendritic cells and B-cells to the site of infection and injury is essential for the host to contain

and eliminate invading pathogens (33). In this study, we tested the interaction and regulation of

three proteins (HO-1, MCP-1 and CCR2) in the process of granuloma formation. HO-1, an

inducible, cyto-protective protein has been implicated in many inflammatory disease as well as

mycobacterial infections (45). We hypothesized that HO-1 plays a role in granuloma formation

by regulating MCP-1 and CCR2 expression in mouse monocytes and therefore regulating the

cellular recruitment of these immune cells from the periphery to the site of infection and injury.

MCP-1 is a chemokine responsible for creating a gradient for the chemotaxis of immune cells

from the periphery to the site of infection and CCR2 is the cell surface receptor which is bound

by MCP-1 (25). MCP-1 and CCR2 are both highly involved in the process of cellular

recruitment and in this study we demonstrate that HO-1 is a key regulator of these cytokines and

therefore the immune recruitment process and granuloma formation. From our in vitro

experiment using RAW 264.7 mouse monocytes, we observed that HO-1 is induced by M avium

as early as 4 hours post treatment and stays highly expressed for up to 48 hours (Figure 9). Once

activated by M. avium, these monocytes began to express higher levels of both MCP-1 (Figure



















Figure 4-7. HO-1+/+ 6 month control lung. Control mice were inoculated with intranasal PBS








: .99




Figure 4-8. HO-1 +/+ lung showing granuloma formation after 6 months exposure to M. avium
via intranasal inoculation


Ad LA









are: Mycobacterium avium (M. avium), Mycobacterium kansasii (M. kansasii) and

Mycobacterium intracellulare (M. intracellulare). There is little evidence of person-to-person

spread of NTM and it is believed that the environment is the main source or reservoir for these

organisms. NTM disease in AIDS is caused primarily by M. avium and is second only to AIDS

wasting syndrome as the most common cause of death in these patients (6).

Mycobacterium Avium

M. avium is a non-tuberculous mycobacterium which infects humans and animals alike.

M. avium is an opportunistic infectious agent that mostly affects patients with underlying

conditions that compromise local or systemic immunity (7) and has become a major human

pathogen, primarily due to the emergence of the AIDS epidemic. This mycobacterium is found in

the environment, particularly in water sources and is in close contact with human populations

(7). Human infection is believed to be initiated either through the intestinal tract or by the

inhalation of aerosols containing bacteria (7). When inhaled, M. avium enters the body via the

respiratory route through aerosols and the first host cells to encounter the pathogen are bronchial

epithelial cells and alveolar macrophages (7). Mycobacteria use different receptors to gain

access into macrophages: mannose receptors, complement receptors (CR3), type A Scavenger

receptors and in exposed hosts with mycobacteria-specific antibodies, Fcy receptors (7, 8).

M. avium can spread from the initial site of infection to the rest of the body through the

lymphatics or through the blood. At the main site of infection, the bacilli are phagocytosed by

alveolar macrophages (4). This is the first event in which the host develops a response to the

invading pathogen and is vital to the outcome of infection. Of the many virulence factors of

Mycobacteria, their ability to reside and multiply within alveolar macrophages is seen as one of

the most important. Other virulence factors of NTM are: prevention of acidification of

phagocytic vesicles, prevention of phagosomes-lysosome fusion, delay in tumor necrosis factor

13









MCP-1 levels in BALF and serum

When we analyzed the levels of MCP-1 in both BALF and serum, we observed a

significant increase of MCP-1 in the BALF of infected wild type C57BL/6 mice as compared to

uninfected controls and increased levels in infected HO-1 -/- mice as compared to knockout

controls as measured with ELISA (Figure 4-21). Additionally, MCP-1 levels were higher in HO-

1 -/- control mice as compared with wild type controls. MCP-1 levels were also increased in the

sera of mice infected with M. avium as compared to control mice and the levels of MCP-1 in sera

of HO-1 -/- mice infected with M. avium were significantly higher than wild type controls and

HO-1 -/- controls (Figure 4-22).









Mycobacterium avium infection in both HO-1 +/+ and HO-1 -/- mice to test whether the lack of

HO-1 expression results in the formation of unorganized (loose) granulomas and to test whether

HO-1 regulates MCP-1 and CCR2 in this disease model.














2.5

2


1.5


1 -


0.5


4 hour


- 24hour


0I I
Control M. avium ZnPP+ M. avium
Treatments

Figure 4-4. MCP-1 Relative Gene Expression significantly increased (p < .001) in monocytes
after treatment with M avium for 8 and 24 hours as compared to controls (*) and
were significantly lowered when cells were pretreated with ZnPP for 8 and 24 hours
(**) as compared to M avium alone for the same time points. RAW 264.7 cells were
incubated for 4,8 and 24 hours in serum free media (Control) or treated with M.
avium, or both ZnPP and M. avium









BIOGRAPHICAL SKETCH

Doron Regev was born in Tel-Hashomer, Israel. He grew up in Kfar Saba, Israel and

moved to the United States at the age of 8. Doron spent most of his childhood in Rochester, NY

and graduated from Brighton High School in 1995. He earned his bachelor's degree in Biology

from the University at Albany (NY) in 1999. Doron also excelled as a collegiate football player

at Albany, earning a first team All-American award as a place kicker his senior year. Following

college, Doron pursued a career as a football player and in 2001, played for the Rochester

Brigade, a professional arena football team in Rochester, NY. He later decided to embark on a

scientific career and began his research at the University of Rochester, where he worked in a

cardiovascular research lab for two years. He then moved to Gainesville, Florida where he

worked in a pulmonary research lab under Dr. Veena Antony and entered the MS program at the

University of Florida. Upon completion of his master's degree, Doron will continue his studies in

the IPD program at the University of Florida in the hopes of attaining a Ph.D. in medical

sciences.









DAB peroxidase substrate solution (Vector laboratories, Burlingame, CA) for color

development. All slides were counter-stained with Hematoxylin (fisher Scientific, Fair Lawn,

NJ) for 30 seconds. Sections were visualized using a Nikon DIAPHOT inverted microscope.

The ocular is magnified to 10 times (10x) and the objectives used were magnified to lOx, 20x

or40x. Pictures were taken using the SPOT Imaging Solutions software (Sterling Heights, MI).

TIB-71 (RAW 264.7) Cells

RAW 264 (7TIB-71) cells were obtained from American Type Culture Collection

(Manassas, VA). RAW 264 cells are macrophages derived from BALB/C mice and are known to

produce lysozyme. The base medium for this cell line is ATCC-formulated Dulbecco's

Modified Eagle's Medium (DMEM) supplemented with 10% Fetal Bovine Serum (FBS),

Fungizone (MP Biomedicals United States, Solon, OH) and Penicillin-Streptomycin solution

(MP Biomedicals United States, Solon, OH). Cells were grown to confluence in 6-well plates

and the culture medium was replaced with serum-free medium (SFM) to perform the

experiments. Camhi et al. have shown that HO-1 is induced in RAW 264.7 cells with treatment

of LPS (74).

Co-Culture of RAW 264.7 Cells With M. Avium

TIB-71 cell cultures were plated on 60mm culture plates (Coming, Lowell, MA) at a

concentration of 1x10^6 cells per plate and treated with M avium in SFM at a concentration of

50x10^6 bacteria per plate or a ratio of 50:1 bacteria per cell. After reaching confluence, the

plates were incubated at 370 C for different time points (4, 8, and 24 hours) and the cells and

supemates were harvested. All treatments were done in triplicate. Cell culture supemates were

stored in a -80' C freezer. Cell pellets were stored in either Buffer RLT (Qiagen, Valencia, CA)

or RIPA cell lysis buffer (Sigma Aldrich, St. Louis, MO) for RNA isolation and Western Blot

protein analysis respectively. The resulting samples were stored in a -80' C freezer until needed.

30









to the destruction of the MCP-1 chemotactic gradient which would then disrupt cellular

recruitment to the site of infection.

Previous findings along with our results suggest that different cell types in different organ

systems may react differently to altered levels of HO-1. This could be the result of direct

regulation by HO-1 on MCP-1 gene expression via NFKB or the result of over expression of the

CCR2 receptor on monocytes and macrophages in the vicinity of the infection which creates a

negative feedback loop between CCR2 and MCP-1. It has been reported that when HO-1

enzymatic activity is inhibited by ZnPP, the levels of CCR2 increase (48, 49) suggesting that

HO-1 somehow regulates the expression of CCR2 on the surface of monocytes, macrophages

and other immune cells. Our results show that HO-1 -/- mice indeed had increased levels of

CCR2 on monocyte/macrophage cell surfaces as seen by relative gene expression (Figure 11)

and immunohistochemistry (Figure 26). Our findings also suggest that HO-1 normally regulates

the expression of the CCR2 during infection and allows these cells to chemotax along an MCP-1

gradient towards infection. When we analyzed the results from our in vivo mouse model, we

observed that the loss of HO-1 expression led to loose or unorganized granuloma formation in

mice following M. avium infection. The inability of these mice to form solid granulomas led to a

disseminated infection with more inflammation and more lesions covering a greater area of the

lungs, liver and spleen. As Figure 18 shows, HO-1 -/- mice had loose, unorganized granulomas

in the lungs. It is possible that these mice did not contain the mycobacterium as compared to HO-

1 +/+ mice and therefore had disseminated infections. These findings suggest that HO-1 plays a

critical role in the regulation of cellular recruitment to the site of infection and in organized

granuloma formation. When analyzing our HO-1 -/- mouse tissue and immunohistochemistry,

we observed that the lack of the HO-1 gene in mice infected with M avium led to severe
























Figure 4-19. A and B. 100x magnification of an HO-1 +/+ mouse lung after 6 month infection
with M. avium showing CCR2 (brown) co-localizes with granuloma. Blue color
shows counter-stain with Hematoxylin

















Figure 4-20. A and B. 100x magnification of an HO-1 -/- mouse lung following 6 month
infection with M avium showing disseminated expression of CCR2 (brown). Blue
color shows counter-stain with Hematoxylin


























Figure 4-13. 100x magnification of control lung from HO-1 +/+ mouse showing basal levels of
HO-1 (brown).


Figure 4-14. 200x magnification of M avium infected HO-1 +/+ mouse lung tissue showing
increased expression of HO-1 (brown) in granuloma. Blue color shows counter-stain
with Hematoxylin









1 is a primary and specific mononuclear cell chemoattractant from a class of cytokines that are

referred to as the platelet factor 4 (PF4) super family and are related by predicted primary

structural similarities and by conservation of a 4 cysteine motif (51). MCP-1 was first cloned

from mouse fibroblasts as a PDGF-inducible gene termed JE (24,52) and is homologous to

human MCP-1 (24, 53, 54, 55, 56,57). It has been shown that increased levels of MCP-1

following bacterial infection correlate with the influx of CD4+ T cells and macrophages in to the

lungs (25). However, other results suggest that MCP-1 is a mediator of inflammation and can

specifically stimulate the directional migration of T cells as well as monocytes and may play an

important role in immune cell recruitment into sites of antigenic challenge (47).

Previous results show that MCP-1, along with several other chemokines, is controlled by

the Nuclear Factor Kappa Beta (NFKB) signaling pathway (58, 59, 60). MCP-1 creates a

gradient for chemotaxis of monocytes-macrophages, T-cells and natural killer (NK) cells towards

the site of infection and is the ligand for CCR2 which is expressed on cell surfaces of leukocytes

(28). This receptor-chemokine interaction has been shown to induce haptotaxis (the migration of

cells along the gradient of substrate-bound attractant molecules) in mesothelial cells (28). MCP-

1 is characterized by its ability to evoke chemotaxis mainly in monocytes (50). MCP-1 has also

been shown to aid in the recruitment of other mononuclear phagocytes such as: CD45ARO+ T

lymphocytes, B cells, and NK cells (61). In vitro, MCP-1 is chemotactic for mononuclear cells,

but not Neutrophils (62). However, Neutrophils in an inflammatory milieu, can express CCR2,

potentially enabling their chemotaxis to MCP-1 (63). The association between augmented levels

of MCP-1 and the recruitment of mononuclear cells expressing CCR2 plays a crucial role during

chronic inflammatory disease (62). MCP-1 has been shown to be upregulated in HO-1 knockout

mice (64). This suggests a possible inhibitory effect by HO-1 on MCP-1. Alternatively,





























Figure 4-9. HO-1 -/- 6 month control lung. Control mice were inoculated with intranasal PBS.


Figure 4-10. HO-1 -/- lungs showed disseminated infection and loose granuloma formation
following 6 month exposure to M. avium.









bronchial epithelial cells (46). HO-1 is recognized to alter both chemokine production as well as

chemokine receptor expression (74). Recruitment of monocytes to the site of infection is a

complex phenomenon dependant on the expression of chemokines and expression of receptors

for these chemokines on peripheral blood monocytes. HO-1 has been shown to act in cell

mediated immunity in the pleura and infections with M. avium have been shown to increase the

expression of HO-i in mononuclear cells and pleural mesothelial cells (47). HO-1 has been

shown to downregulate the inflammatory response in the lungs by attenuating the expression of

adhesion molecules and inhibiting the recruitment of leukocytes or by repressing the induction of

cytokines and chemokines such as MCP-1 (47). It is not known how HO-1 regulates and

suppresses cytokine expression. It is possible that HO-1 inhibits the actions of NFKB and

therefore abrogates an inflammatory response (45). HO-1 has been shown to directly regulate

MCP-1 mRNA expression trough the degradation of heme (48). Furthermore, HO-1 induction

results in suppression of monocyte chemotactic response via inhibition of CCR2 expression (49).

Monocyte Chemoattractant Protein-1 (MCP-1)

MCP-1 (Also known as monocyte chemotactic and activating factor (MCAF)) is a 76

amino acid peptide that is selectively chemotactic for peripheral blood monocytes (50). MCP-i

is an 8.7-kDa protein that has specific chemoattractant and activating activity for monocytes in

acute inflammatory conditions (25).The regulated interactions of chemokines with their

respective receptors are thought to mediate the controlled recruitment of specific leukocyte

subpopulations required during host defense and inflammation. MCP-1, a member of the CC

motif chemokine family, is secreted by pleural mesothelial cells, endothelial cells, fibroblasts,

monocytes, macrophages and leukocytes in response to inflammatory signals such as IL-1 and

TNF-alpha and bacterial infection (51). CC chemokines have two conserved, adjacent cysteines

near their amino terminus and are predominantly chemotactic for mononuclear cells (65). MCP-

19









points (2, 4 and 6 months) and the lungs, spleen and liver were harvested. BALF, BAL cells and

serum were collected.

Cytokine Studies

MCP-1 levels in cell culture supernatants, mouse sera and BALF were measured using

Enzyme-Linked ImmunoSorbent Assay (ELISA). We used a Quantikine Mouse CCL2/JE/MCP-

1 immunoassay kit according to manufacturer recommendation (R&D systems Inc.,

Minneapolis, MN). The cells and media are collected and centrifuged at 2000 RPM for 5

minutes. The culture supernates were collected and stored in a -80 C freezer until needed. 50

[tL of each sample (supernates, BALF, or serum) was used in the assay to measure MCP-1

levels. The OD was measured at 450 nm in a Biotek Synergy 2 microplate reader using Gene5

software (Biotek Industries, Winooski, VT).

Real-Time Polymerase Chain Reaction (RT-PCR) Analysis

Total RNA from cultured RAW 264 cells was purified and diluted with RNase-free water

to 100 ng/L; then, 10 ptL of each sample were reverse transcribed into combinational DNA

(cDNA). After the reverse transcription reaction was finished, 80 [tL of RNase-free water were

added to each sample. 10ptL of diluted cDNA product were mixed with 25 [tL of SYBR Green

JumpStart Taq ReadyMix, 0.5 [tL of internal reference dye, H20 and 2 [tL of specific

oligonucleotide primers (80 nM final concentrations) to a total volume of 50 ptL for

quantification of the real-time polymerase chain reaction (PCR). The quantification of real-time

PCR was performed by using the SYBR Green method on the Applied Biosystems 7500 Real

Time PCR System with the following profile: 1 cycle at 940C for 2 minutes; 40 cycles at 940C

for 15 seconds, at 600C for 1 minute, and at 720C for 1 minute; and the at acquired fluorescent

signal from the elongation step. Beta-actin or 18s rRNA was used as a house-keeping internal

control. The real-time PCR products were confirmed by electrophoresis on 2% agarose gels.

32










TABLE OF CONTENTS

page

A C K N O W L E D G M E N T S ...............................................................................................................3

LIST OF FIGURES ................................... ............ .. .............................6

ABSTRACT ............................ .......................................................8

CHAPTER

1 IN TRODU CTION ................... ............. .................................. .............. 10

Hypothesis ................................. ... ........................................II
Obj active ........................................ ........ ............... ...............11

2 BACKGROUND .................................................. .......................12

Mycobacterium ................................. ....... ...........12
M ycobacterium Avium ............. .......... .. ........ .... .. ............. .... 13
Mycobacterium Avium Complex (M AC)................................... .................. 14
Host Response To Infection.............................................. 15
Formation Of Granuloma ......................................... 16
H em e O xygenase-i (H O -1) .......................................................................................... ... ....... 17
Monocyte Chemoattractant Protein-i (MCP-1) ....................................................... 19
Chem okine (C-C M otif) Receptor 2 (CCR2) ....................................................... 21

3 M ATERIALS AND M ETHODS ................................................. ...............27

HO-1 Knockout M house M odel ........................................................................... 27
M. Avium culture..................... .... .. ..................... 28
Collection Of Serum ....................................... ..........28
Bronchial Alveolar Lavage Fluids (BALF)........................................................ ......... 28
Tissue H harvest ...................................................... ........ 29
Immunohistochem istry .................. .................................................... .............. 29
TIB-71 (RAW 264.7) Cells ............................................... ...............30
Co-Culture of RAW 264.7 Cells With M. Avium.......... ...............................30
HO-1 Inhibition By Zinc Protoporphyrin-IX In Cell Cultures.............................................31
Mouse Model For M Avium Infection ................................................ 31
Cytokine Studies ....................... ......................... ..........32
Real-Time Polymerase Chain Reaction (RT-PCR) Analysis ......................................32
Statistical A nalysis............................................... 33

4 RESULTS ...........................................................................35

In Vitro Results.................. ................................... .............. 35
HO-1 is induced by M avium in RAW 264.7 cells............................. .............35

4









1, and two constitutive forms, HO-2 and HO-3 (40). Also known as Heat Shock protein 32

(HSP32), HO-1 is the rate limiting enzyme involved in the degradation of heme, a potent

oxidant. In addition to its role as a key enzyme in heme degradation, HO-1 has been shown to be

anti-inflammatory and anti-oxidative through its breakdown of heme (41). HO-1 is a 32 kDa

microsomal stress response protein that is induced by oxidative stress, inflammation and

bacterial infection and is secreted by many cell types (41). Mitzuno et al. (41) have shown that

among peripheral blood leukocytes, monocytes are the principal source of HO-1 when stimulated

in vitro and that his production plays a role in systemic inflammation. HO-1 has been shown to

be induced by glutathione depletion, lipopolysaccharide (LPS) and both hyperoxia and hypoxia

in vivo (42). In addition, HO-1 is induced by various cytokines and growth factors (43). The 5'-

flanking region of the HO-1 gene contains binding sites for the transcription factors that regulate

inflammation, including nuclear factor-kappa B and activator protein 1(74). However, these do

not appear to mediate lipopolysaccharide-induced HO-1 gene expression. This transcription

factor may also be important in the regulation of HO-1 by pro-inflammatory stimuli (44). HO-1

plays a central role in the defense against oxidative and inflammatory insults in the lung and has

been shown to be upregulated in many pulmonary diseases (45). HO-1 deficiency, however, is

associated with chronic inflammation and increased leukocyte recruitment in mice and in

humans (41). Zampetaki et al (46) have shown that HO-1 deficiency in humans and mice results

in chronic inflammation and increased leukocyte recruitment. The byproducts of HO-i

enzymatic activity are cyto-protective, anti-inflammatory and may act as anti-oxidants at the

right concentrations (44). HO-1 has been implicated in the protection of lung tissue during

oxidative stress, but the expression and cellular distribution of HO-i is poorly characterized. In

healthy lung tissue, HO-1 has been shown to be expressed in alveolar macrophages and in









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and interleukin 8 production by rheumatoid synoviocytes. Effects of anti-rheumatic
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inflammation upregulates chemokine receptors and induces neutrophil migration to
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65. Pittock, ST, Norby, SM, Grande, JP, Croatt, AJ, Bren, GB, Badley, AD, Caplice, NM,
griffin, MD, Nath, KA: MCP-1 is up-regulated in unstressed and stressed HO-1
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Heme: A novel inducer of MCP-1 through HO-dependent and HO-independent
mechanisms. Am. J. Physiol Renal Physiol 2003; 284: F546-F554

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Expression and Functional Response to Monocyte Chemotactic Protein (MCP-1) During
the Differentiation of Human Monocytes: Role of Secreted MCP-1 in the Regulation of
the Chemotactic Response. Blood. 1999;4:875-883

68. Charo, IF, Myers, SJ, Herman, A, Franci, C, Conolly, AJ, Coughlin, SR: Molecular
cloning and functional expression of two monocyte chemoattractant protein-i receptors
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69. Warmington, KS, Boring, L, Ruth, JH, Sonstein, J, Hogaboam, CM, Curtis, JL, Kunkel,
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Respir Cell Mol Biol. 1995;13:387-398









CHAPTER 4
RESULTS

In Vitro Results

HO-1 is induced by M. avium in RAW 264.7 cells

We stained RAW 264.7 cells for HO-1 to test whether the expression levels of HO-1 are

increased after insult with M. avium. Our results showed that HO-1 was induced by M. avium in

RAW 264.7 cells after 4 hours (Figure 4-2) as opposed to controls (Figure 4-1). HO-1 was still

expressed at 8, 24 and 48 hours after exposure to M. avium as well (results not shown).

We next looked at mRNA levels of HO-1 in RAW 264.7 cells in the presence and absence of M

avium in order to see whether M avium induces gene expresison of HO-1. Our results showed

that HO-1 expression was induced in a time dependent manner in this mouse monocyte cell line

after M avium treatment (Figure 4-3).

MCP-1 relative gene expression in RAW 264.7 cells

Following the same protocol as explained above, we analyzed the mRNA levels of MCP-i

in RAW 264.7 cells using real time PCR. After treatment with M. avium, MCP-1 mRNA levels

increased in a time dependent manner as compared to controls, but these levels were abrogated

when we treated the cells with ZnPP, a competitive inhibitor of HO-1 enzymatic activity, prior to

M. avium exposure (Figure 4-4).

CCR2 relative gene expression in RAW 264.7 cells

In order to test whether M. avium infection and HO-1 inhibition affect gene expression of

CCR2, mRNA levels of CCR-2 were measured in TIB-71 (RAW 264.7) cells. Our results

indicate that when these cells are treated with ZnPP, CCR2 expression is significantly increased

on the surface of mouse monocytes and this increase is time dependent (Figure4-5).



















4


S4 hour

S8 hour

* 24 hour


4


4, J,


--1-r


I1


Control M. avium ZnPP+M. avium
Sample
Figure 4-5. CCR-2 Relative Gene Expression was significantly increased (p<.05 ) in M avium
treated monocytes as compared with controls at 4 hours (*), 8 hours (**), and 24
hours (***) and in cells treated with ZnPP and M avium as compared to controls.
RAW 264. 7 cells were incubated for 4, 8, and 24 hours in serum free media
(Control), treated with M. avium or treated with both ZnPP and M. avium









14. Taylor, RH, Falkinham, JO, III, Norton, CD, LeChevallier, MW: Chlorine, chloramine,
chlorine dioxide, and ozone susceptibility of Mycobacterium avium. Appl Environ
Microbiol 2000;66:1702-5

15. von Reyn, CF, Maslow, JN, Barber, TW, Falkinham, JO, III ,Arbeit, RD: Persistent
colonization of potable water as a source of Mycobacterium avium infection in AIDS.
Lancet 1994; 343: 1137-41

16. Alamelu, R: Immunology of tuberculosis. Indian J. Med. Res. 2004;120:213-232

17. Quesniaux, V, Fremond, C, Jacobs, M, Parida, S, Nicolle, D, Yeremeev, V, Bihl, F,
Erard, F, Botha, T, Drennan, M, Soler, MN, Bert, M, Schnyder, B, Ryffel, B: Toll-like
receptor pathways in the immune responses to mycobacteria. Microbes and Infection
2004;6:946-959

18. Stenger, S, Modlin, RL: Control of Mycobacterium tuberculosis through mammalian
Toll-like receptors. Curr. Opin. Immunol. 2002; 14:452-457.

19. Heldwein, KA, fenton, MJ: The role of Toll-like receptors in immunity against
mycobacterial infection. Microb. Infect. 2002;4:937-944

20. Medzhitov, R, Biron, CA: Innate immunity, Curr. Opin. Immunol. 2003;15:2-4

21. Akira, S: Mammalian Toll-like receptors, Curr. Opin. Immunol. 2003;15:5-11

22. Takeda, K, kaisho, T, Akira, S: Toll-like receptors. Annu. Rev. immunol. 2003; 21:335-
376.

23. Medzhitov, R, Preston-Hurlburt, P, Janeway, CA: A human homologue of the
Drosophila Toll protein signals activation of adaptive immunity. Nature 1997;388:392-
397

24. Krutzik, SR, Tan, B, LI, H, Ochoa, MT, Liu, PT, Sharfstein, SE, Graeber, TG, Sieling,
PA, Liu, YG, Rea, TH et al: TLR activation triggers the rapid differentiation of
monocytes into macrophages and dendritic cells. Nat Med 2005;11:653-660.

25. Huffnagle, GB, Strieter, RM, Standiford, TJ, McDonald, RA, Burdick, MD, Kunkel, SL,
Towes, GB: The Role of Monocyte Chemotactic Protein-i (MCP-1) in the Recruitment
of Monocytes and CD4+ T Cells During a Pulmonary Crytococcus neoformans infection.
The journal of immunology 1995;

26. Emery, P, Salmon, M: The Immune response. 2 Systemic mediators of inflammation.
Br. J. Hosp. 1991;45:164-168

27. Schall, TJ: Biology of the RANTES/SIS cytokine family. Cytokine 1991;3:165











1600


1400


1200 -


1000 -


800 -

t 600 -


400 -


200 -



HO-1 +/+ Control HO-1+/+ M. avium HO-1-/- Control HO-1-/- M. avium

Figure 4-21. MCP-1 levels are significantly increased (p < .001) in BALF of infected HO-1 +/+
and HO-1 -/- mice as compared with controls (*). Basal levels of MCP-1 are
significantly higher (p < .001) in HO-1 -/- control mice as compared to HO-1 +/+
control mice (**).









secretion by infected host cells, uptake by epithelial cells and production of receptors for

macrophage binding (9). Phagocytosed pathogens are normally transported from the

phagosomes to lysosomes within the macrophages and are effectively destroyed after phago-

lysosomal fusion. The most well-characterized antimicrobial mechanisms of the macrophage are

the ones that involve oxidative damage: the respiratory burst and nitric oxide (NO) production

(9). These two systems work synergistically in killing many microbes (7, 10). Macrophages that

have phagocytosed the bacilli normally die and form a central area of necrosis or a caseum; the

pathogen is then contained within these caseous granulomas (11).

Mycobacterium Avium Complex (MAC)

Mycobacterium avium complex (MAC) is generally referred to as an opportunistic

pathogen since it usually infects patients with established lung damage (11). Mycobacteria

included in the MAC family are classified as acid-fast, slowly growing bacilli that may produce a

yellow pigment in the absence of light (1). Other species of Mycobacteria which are included in

MAC include: M. avium paratuberculosis, M. avium silvaticum, M. avium hominissuis and M

avium colombiense (3). MAC in AIDS patients most often causes a disseminated illness

(bacteria is spread though the blood stream) and can cause many symptoms throughout the body.

The risk of MAC is inversely related to the patient's CD4+ T-cell count, and increases

significantly when the CD4+ T-cell count decreases below 50 cells/mm3 of blood (3). 98% of

MAC infections in AIDS patients are due toM. avium (1). Isolates from MAC infected patients

are commonly referred to as Mycobacterium avium hominissuis, since this strain is found mostly

in humans. Like most NTM, MAC bacteria are found in air, water, soil, foods, some tobacco

products, and in many animals. Covert et al showed that person-to-person transmission of MAC

bacteria is unlikely, suggesting that humans contract this disease from the environment (12).

Recently, there has been a growing concern about human exposure to MAC through drinking

14









CHAPTER 6
FUTURE CONSIDERATIONS

Having established an HO-1 -/- animal model ofM. avium infection and granuloma

formation, we can now focus on the direct role of HO-1 in the innate and adaptive immune

responses, specifically focusing on granuloma formation. We plan to further elucidate the role of

HO-1 in regulating cytokines such as MCP-1 and CCR2 and how this regulation affects cellular

recruitment from the periphery to sites of infection and inflammation. As stated previously, HO-

1 expression may exert different physiological changes in different organ systems and cell types.

We can now study the effects of HO-1 or lack thereof, in several organs, cell types and in

different states of health. We can also concentrate on the different aspects of heme catabolism

by HO-1 which may affect this immune process. We plan on testing the affects of free iron

(Fe+), Billirubin, and C02 on granuloma formation and the immune response to M. avium

infection. Another challenge will be to test whether it is possible to rescue the cyto-protective

role of HO-1 in HO-1 -/- mice by treating them with one or more of the catabolic byproducts of

heme degradation. Another possibility is the use of HO-1 therapy to treat NTM infected patients

with HIV or AIDS in the hopes of rescuing their immune function. With these future studies, we

hope to contribute not only to the scientific field of microbiology, but also to the clinical and

therapeutic areas of medicine. Hopefully our findings will help us understand the mechanisms of

NTM infection and help prevent such diseases in the future. Alternatively, we hope that our

study will help elucidate the role of HO-1 in NTM disease and will lead to a better understanding

of how to approach and treat other disease caused by both NTM and Mycobacterium

tuberculosis.









ACKNOWLEDGMENTS

I would like to acknowledge Dr. Veena Antony and especially thank her for her guidance

in my research and my writing. I would also like to thank the other members of my committee,

Dr. Henry Baker and Dr. Reuben Ramphal for all the input they provided. Thanks to Dr. Ana

Montes-Worboys and Dr. Yimu Lai for their continued help and technical assistance in the lab

and thanks to Edward Hensel for showing me the clinical aspects of medical research. I would

like to thank Dr, Kamal Mohammed and Dr. Nasreen Najmunnisa for their help and guidance

along the way. Finally, I am grateful to my parents, Michael and Dalia and my sister, Dana for

their support and inspiration throughout my life.











i.. ,'-I.
.i cr- '*
^ *^ i: 1' *7 <

3, A- *'
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.I .d.^ !;^

. VL -


A &r% .'' I ` Z O-e' 6! B Bi. 2'aH -'-%I I r I /-! M1;

Figure 4-11. A) 100x magnification H&E stain of an HO-1 +/+ control mouse lung. B) 100x
magnification H&E stain of an HO-1 +/+ mouse infected with M avium for 6
months showing granuloma formation

















Figure 4-12. A) lOOx magnification H&E stain of HO- -/- saline control lung. B) 100lx
magnification H&E stain of HO-1 -/- showing loose, unorganized granulomas and
disseminated infection in lung tissue following 6 month exposure to M. avium


r.
e : ~-'~::C~









HO-1 protein expression in mouse lung tissue

We stained the lungs tissue of HO-1 +/+ control and infected mice to study whether M

avium infection induces HO-1 expression. HO-1 levels were up-regulated in granulomatous

tissue in HO-1 +/+ mouse lungs infected with M avium as compared to Control mice. Figure 4-

13 shows a 100x magnification of a control lung from an HO-1 +/+ mouse which was inoculated

with saline (PBS) which was stained for HO-1. This tissue exhibited basal levels of HO-1.

Figures 4-14 and 4-15 show a 200x magnification of an HO-1 +/+ mouse lung stained for HO-1.

This mouse was inoculated withM. avium for 6 months and shows upregulation of HO-1 in

granulomatous tissue.

CCR2 expression in mouse lung tissue

To test and confirm previous results that showed that HO-1 regulates the expression of

CCR2, we looked at CCR2 expression in the lung tissue of HO-1 +/+ and HO-1 -/- infected and

control mice. Figure 4-16 shows that HO-1 -/- mice have higher basal levels of CCR2 in lung

tissue. CCR2 levels were up-regulated in lung tissue of infected HO-1 +/+ mice as compared to

uninfected controls (Figure 4-17). Additionally, we observed higher levels of CCR2 in infected

lungs of HO-i -/- mice as compared to infected HO-1 +/+ mice (Figure 4-18 ). In HO-1 +/+

mouse lung tissue, CCR2 co-localized to granulomas (figure 4-19). Our results showed that

CCR2 is normally regulated by HO-1 in the lungs of HO-1 +/+ mice following infection. Figure

24 shows that CCR2 is co-localized to the granuloma and is not expressed in other areas of the

lung. In HO-1 -/- mice we see that this regulation is lost and CCR2 is expressed in a much larger

area of the lung and is disseminated after infection as compared to CCR2 expression in HO-1

+/+ tissue from infected mice (Figure 4-20).









Kanakiriya et al (65) have shown that inhibition of HO-1 with Zinc protoporphyrin (ZnPP), a

specific HO-1 inhibitor, prevented the hemin-induced expression of MCP-1 mRNA and that the

active form of Iron can also induce the expression of both HO-1 and MCP-1 (45). During

infection and inflammatory disease, the increased release of MCP-1 attracts T-lymphocytes and

macrophages to the site of infection and results in granuloma formation (54). ZnPP prevented

the expression of MCP-1 by hemin at 6 hours; examination at later time points demonstrate an

increasing level of expression of MCP-1 mRNA despite the continued presence of this inhibitor

of HO activity; indeed, at 18 hours, the level of expression of MCP-1 was increased almost

threefold in the presence of ZnPP (47). Thus, MCP-1 can also be induced by HO-1 independent

pathways, but this leads to a delayed expression of the chemokine (47). It is believed that MCP-

1 plays a crucial role in the development of disseminated MAC disease. Some studies have

shown that MCP-1 can act as a negative regulator for the CCR-2 cell surface receptor (66).

Chemokine (C-C Motif) Receptor 2 (CCR2)

CCR2 is a seven-transmembrane-spanning G-protein coupled receptor expressed on the

cell surface of leukocytes (60) (Figure 2-4). This receptor binds MCP-1 with high affinity and is

activated upon ligand binding (60). MCP-1 interacts with CCR2 which has two isoforms,

CCR2A and CCR2B (29, 68). Activation of CCR2 leads to downstream activation of

Phospholipase C (PLC) which cleaves the molecule Phosphotidyl inositol (4, 5) bisphosphate

(PIP2) (68). This cleavage forms two second messenger molecules called Inositol trisphospahte

(IP3) and Diacylglycerol (DAG) which induce intracellular signaling events and trigger

inflammation (68). Specifically, DAG has been shown to activate Protein Kinase C (PKC) and

IP3 has been shown to trigger the release of calcium from internal cellular stores (60). These

events promote the activation of the Mitogen Activated Protein Kinase (MAPK) pathway and

induce differentiation and chemotaxis of leukocytes (60) (Figure 2-5). CCR2 is expressed on

21




































2009 Doron Regev













a Initiation of Immune response
Antigenic activation
1--t--1



Microcirculation k Mast cell NK cell y& T cell Dendritic
ro Histiocyte cell

Monocyte 1
Neutropily TNF IFNy
Q ?TNF IFN-y Antigen
_k Chermokines
Recruitment vi ya c 5

Developing granulomatous inflammation b Production of Ag-specific T cells in lymph node
Thi
TNF CDT cell









Antigen-loaded
dendrilic cell


-- Persistent
antigen


Pathogenesis of granuloma formation
Expert Reviews in Molecular Medicine 2005 Published by Cambridge University Press


Figure 2-2. Formation of granuloma involving pathogen, macrophages, T-cells, and B cells.









supplemented with Ethidium bromide for UV imaging of DNA. The molecular weight of the

wild type and mutant gene products are 180base pairs and 290 base pairs respectively.

M. Avium culture

M. avium subspecies avium Chester (ATCC# 15769) was maintained in ATCC medium 90

Lowenstein Jenson medium and grown in Lowenstein-Jensen Medium Slants (BD Biosciences,

San Jose, CA) according to manufacturer's instructions. Alternatively, colonies were grown on

Middlebrook and Cohn 7H10 agar plates (BD Biosciences, San Jose, CA) and incubated for 14

days at 37 degrees in 95% oxygen and 5% carbon dioxide. A stock solution was prepared and the

concentration was measured by reading the optical density (OD) using a spectrophotometer at

600nm (BioRad, Hercules, CA). Bacteria were frozen in 1ml aliquots in 10% glycerol at -800 C

at a concentration of 1.3 x 109 Colony forming units (cfu)/ml. Frozen aliquots were thawed and

briefly sonicated before each use.

Collection Of Serum

The mice were euthanized in a desiccator with an overdose of Isoflourane, an analgesic

(Webster veterinary supply, Sterling, MA). Then, whole blood was collected through the

abdominal aorta using a 25 gauge needle. The blood was left at room temperature for 30 minutes

to clot and then centrifuged at 12,000 rpm to separate the serum from the red blood cells (RBCs).

The serum was then aliquoted and stored in a -80' C freezer for further analysis.

Bronchial Alveolar Lavage Fluids (BALF)

BALF was collected by lighting the trachea using thread and placing a catheter into the

airway through the trachea. Fluids were collected by injecting 800-1000 [tL of Hanks' Balanced

Salt Solution (HBSS) into the mouse lung via canulation of the trachea. The fluid was then re-

drawn and the process was repeated twice for a total volume of 1600-2000 [tL BALF. The fluid

was placed on ice and then centrifuged at 1500g to pellet the cells and separate the supernatant.

28









water due to its high resistance to most chemical disinfectants in water treatment processes and

its high prevalence in biofilms in water distribution systems (13, 14, 15). Because most

Mycobacteria are intracellular pathogens, the host cells, alveolar macrophages (AM) in this case,

can actually serve as a barrier to the delivery of drugs to the intracellular environment (16).

MAC organisms have shown to have resistance to many antimycobacterial drugs, which adds to

the challenges of treating this disease.

Host Response To Infection

After mycobacterial infection, the innate and adaptive immune systems respond with the

recruitment of immune cells to the site of injury. The bacilli are recognized by host immune cells

via Toll-Like Receptor (TLR) 2 ligation (17). TLRs are pattern recognition receptors (PRRs)

which recognize and bind to mycobacterial cell wall components and other pathogenic materials.

TLRs are believed to represent key receptors for the recognition of mycobacterial antigens and

activation of macrophages and Dendritic cells (DC), as well as other cells of innate immunity,

thereby likely modulating the adaptive immune response (15,17,19). A variety of microbial

products recognize and activate mammalian TLRs, facilitating the transcription of genes

involved in regulating the adaptive immune response, including chemokines, cytokines and co-

stimulatory molecules (15,20,21,22). Mammalian TLRs represent a structurally conserved

family of membrane receptors, which have homology to the Drosophila Toll system (17, 20).

TLR signaling leads to the nuclear translocation of the transcription factor nuclear factor-xB

(NFKB) via a MyD88 dependent or independent manner (9) (Figure2-1). NFKB is involved in

the expression of many immune response genes, such as those encoding cytokines. TLR

signaling also triggers differentiation of monocytes into macrophages and dendritic cells

allowing for a more potent innate and adaptive immune response (9, 24). Cytokines are likely to

be important mediators during the pulmonary inflammatory response (25). It is also believed

15









41. Mitzuno, K, Toma, T, Tsukiji, H, Okamoto, H, Yamazaki, H, Ohta, K, Ohta, K,
Kasahara, Y, Koizumi, S, Yachie, A: Selective expansion of CD16highCCR2-
subpopulation of circulating monocytes with preferential production of haem Oxygenase
(HO)-1 in response to acute inflammation. British Society of immunology, clinical and
Experimental Immunology. 2005;142:461-470

42. Lakari, E, Pylkas, P, Pietarinen-Runtti, P, Paakko, P, Soini, Y, Kinnula, V: Expression
and Regulation of Hemeoxygenase 1 in Healthy Human Lung and Interstitial Lung
Disorders. Human Pathology 2001;32:1257-1263

43. Kanwar, Yashpal, S: A dynamic interplay between monocyte chemoattractant protein-i
and heme oxygenase-1: Implications in renal injury. Kidney International 2005;68:896-
897

44. Rushworth, SA, O'Connell, MA: Haem oxygenase-1 in inflammation. Biochemical
Society transactions 2004;32(Pt 6): 1093-4

45. Fredenburgh, LE, Perella, MA, Mitsialis SA: The Role of Heme Oxygenase-1 in
Pulmonary Disease. Am. J Respir Cell Mol Biol. 2006;36:158-165

46. Zampetaki, A, Minamino, T, Mitsialis, SA, Kourembanas, S: Effect of Heme
Oxygenase-1 Overexpression in Two Models of Lung inflammation. Experimental
Biology and Medicine 2003;228:442-446

47. Mohammed, KA, Nasreen, N, Ward, MJ, Mubarak, K, Rodriguez-Panadero, P, Antony,
VB: Mycobacterium-Mediated Chemokine Expression in Pleural Mesothelial Cells: Role
of C-C Chemokines in Tuberculous Pleurisy. The Journal of infectious Disease
1998;178:1450-1456

48. Kanakiriya, KRS, Croatt, AJ, Haggard, JJ, Ingelfinger, JR, Tang, SS, Alam, J, Nath, KA:
Heme: A novel inducer of MCP-1 through HO-dependent and HO-independent
mechanisms. Am. J. Physiol Renal Physiol 2003; 284: F546-F554,

49. Morita, T., T. Imai, T. Yamaguchi, T. Sugiyama, S. Katayama, and G. Yoshino:
Induction of heme oxygenase-1 in monocytes suppresses angiotensin II-elicited
chemotactic activity through inhibition of CCR2: role of bilirubin and carbon monoxide
generated by the enzyme. AntioxidRedox Signal 2003; 5:439-447.

50. Zachariae CO, Anderson AO, Thompson HA, et al: Properties of monocyte chemotactic
and activationg factor (MCAF) purified from human fibrosarcoma cell line. J. Exp. Med.
1990;171:2177-82

51. Taub, DD, Proost, P, Murphy, WJ, Anver, M, Longo, DL, Van Damme, J, Oppenheim,
JJ: Monocyte Chemotactic Protein-i (MCP-1), -2, and -3 Are Chemotactic for Human T
Lymphocytes. The Journal of Clinical Investigation, Inc. 1995;95:1370-1376









28. Lundien, MC, Mohammed, KA, Nasreen, N, Tepper, RS, Hardwick JA, Sanders, KL,
Van Horn RD, Antony, VB: Induction of MCP-1 Expression in Airway Epithelial Cells:
Role of CCR2 in Airway Epithelial Injury. Journal of Clinical Immunology
2002;22:144-152

29. Nasreen, N, Mohammed, KA, Galffy, G, Ward, MJ, Antony, VB: MCP-1 in pleural
injury: CCR2 mediates haptotaxis of pleural mesothelial cells. m J Physiol Lung Cell
Mol Physiol 2000;278:L591-598

30. Oppenheim, JJ, Zachariae, COC: Properties of a novel pro-inflammatory supergene
"intecrine" cytokine family. Annu. Rev. immunol. 1991;9:617

31. Schall, TJ: Biology of the RANTES/SIS cytokine family. Cytokine 1991;3:165

32. Baggiolini, M, Dewald, B, Moser, B: Human Chemokines: an update. Annu. Rev.
Immunol. 1997;15:675-705

33. Ehlers, S, Kutsch, S, Ehlers, EM, Benini, J, Pfeffer, K: Lethal granuloma Disintegration
in mycobacterial-Infected TNFp55-/- Mice Is Dependent on T Cells and IL-12. J.
immunol. 2000;165:483-492

34. Lee, JS, Lee JY, Son JW, Oh J, Shin DM, Yuk JM, Song CH, Paiks TH, Jo EK:
Expression and Regulation of the CC-Chemokine Lignad 20m During Human
Tuberculosis Scandinavian Journal of Immunology 2007; 67(1):77-85

35. Kaufmann, S: Protection against tuberculosis: cytokines, T cells, and macrophages. Ann
Rheum Dis 2002;61:ii54-ii58

36. Dannenberg, AM, Dannenberg, GA, Rook, W: Pathogenesis of pulmonary tuberculosis:
an interplay of tissue damaging and macrophage activating immune responses. In
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37. Jagirdar, J, Zapzag, D: Pathology and insights into the pathogenesis of tuberculosis. In
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Figure 4-1. 400x magnification stain of RAW 264.7 cells after 4 hours of incubation in SFM
showing basal levels of HO-1. Blue color shows counter-stain with Hematoxylin


Figure 4-2. 400x stain of RAW 264.7 cells after 4 hours treatment with M. avium showing
increased levels of HO-i expression (brown). Blue color shows counter-stain with
Hematoxylin.











F 2+ Ferritin
Heme- Fe Fet Biliverdin
oxygenase Reductase

Heme Biliverdin Bilirubin


CO

Figure 2-3. Degradation of heme by HO-1. HO-1 catalyzes heme degradation to biliverdin-IX,
CO, and iron. These metabolites mediate the antiapoptotic, anti-inflammatory,
vasodilatory, anticoagulant, antioxidant, and antiproliferative properties of HO-i
(Fredenburgh et. al).


* Ligand binding sile V-T
N N-ytyc0iiadtiun sies v
, DRY motif
G protein binding site
* GRKs binding site
T Targets for GRKs


Figure 2-4. CCR2 structure. Regions implicated in ligand binding, coupling of effector
molecules and suggested targets for GRK and JAK are highlighted.
(apresslp.gvpi.net)

















Toll-like receptor


IRAK


TRAF6


Nucleus


Figure 2-1. Recognition of an appropriate ligand by TLR-2 (for example, lipopolysaccharide)
triggers the Toll-like receptor to recruit MyD88. MyD88 interacts with the Toll-like
receptor through its own Toll/IL-1 receptor domain and in turn engages the serine-
threonine kinase IRAK though a death domain. Signal transduction factors such as
TRAF6 carry the signal through a series of phosphorylations until NFKB is ultimately
released to the nucleus where it can activate the transcription of appropriate immune
response genes. Allan Genome Biology 2000 1:reports0079 doi:10.1186/gb-2000-1-
6-reports0079









Hypothesis

Our hypothesis was that HO-1 plays a key role in granuloma formation following

mycobacterial infection by regulating the expression of CCR2 and MCP-1 in mouse monocytes,

therefore, influencing the recruitment of these inflammatory cells to the site of injury. In HO-1

+/+ mice, we expected to find high levels of MCP-1 in the lung following infection with M

avium, creating a gradient for chemotaxis of immune cells from the periphery to the site of

injury. In HO-1 -/- mice, in which the HO-1 gene was mutated and knocked out, we expected to

see high levels of MCP-1 and CCR2 in the periphery as well as in the lung following infection

with M avium., therefore, causing the gradient for chemotaxis to be disturbed and inflammation

to be disseminated.

Objective

Our objective was to develop a murine model of M. avium infection and granuloma

formation in order to elucidate the role of HO-1 and its regulation of MCP-1 and CCR2 in mouse

monocytes.









CHAPTER 1
INTRODUCTION

Non-Tuberculous Mycobacteria (NTM) are a group of Mycobacteria that are not members

of the Mycobacterium tuberculosis complex. NTM are a major cause of opportunistic infection

in immunocompromised and healthy hosts. These organisms can cause disease in animals and

humans and have become an increasing source of infection among patients infected with Human

Immunodeficiency Virus (HIV) or Acquired Immune Deficiency Syndrome (AIDS) (1).

Mycobacterium avium complex (MAC) is the most common disseminated bacterial infection in

untreated patients with AIDS. A hallmark of disseminated MAC infections is the formation of

granulomas in multiple organs including the liver, spleen, lymph nodes, bone marrow, and lung

(1). Granulomas are lesions in tissue that are formed by the aggregation of activated

macrophages, T-cells and fibroblasts and are considered a defense mechanism against invading

pathogens. Importantly, bacteria are not always eliminated within the granuloma, but can

become dormant, resulting in a latent infection (2). In disseminated mycobacterial disease, the

function and structure of granulomas are either absent or compromised. This leads to a failure of

the host defenses to contain the bacterium and to further pathology. Our current study aims to

elucidate the role of Heme Oxygenase-i (HO-1), a cytoprotective enzyme, in the formation of

organized granulomas. Specifically, we are looking at the role of HO-1 in the regulation of two

cytokines, Chemokine Receptor 2 (CCR2) and Monocyte Chemoattractant Protein-i (MCP-1)

both of which are responsible for the recruitment of inflammatory cells to the site of infection.

Recruitment of immune cells to the site of infection is a vital step in granuloma formation and if

the process is inhibited or altered, the Mycobacterial infection may not be contained.









cDNA was amplified using mRNA-specific primers for mouse 18S rRNA (forward: 5'-

TGTCTCAAAGATTAAGCCATGCAT-3', reverse: 5'-

AACCATAACTGATTTAATGAGCCATTC-3'), mouse MCP-1 (forward: 5'-

GGCTCAGCCAGATGCAGTTAA-3', reverse: 5'CCTACTCATTGGGATCATCTTGCT-3')

mouse CCR2 (forward: 5'-CAACTCCTTCATCAGGCACAR-3' reverse: 5'-

GGAAAGAGGCAGTTTGCAAAG-3') mouse HO-1 (forward: 5'-

CTTTCAGAAGGGYCAGGTGWCC-3', reverse: 5'-GTGGAGMCGCTTYACRTAGYGC-3').

Data analysis was carried out by using the ABI sequence-detection software using relative

quantification. The threshold cycle (Ct), which is defined as the cycle at which PCR

amplification reaches a significant value, is expressed as the mean value. The relative expression

of messenger RNA (mRNA) was calculated by using the Ct method (where Ct is the value

obtained by subtracting the Ct value of the housekeeping gene -actin mRNA from the Ct value of

the target mRNA). The amount of the target relative to B-actin or 18s rRNA mRNA was

expressed as 2-(ct)

Statistical Analysis

The data obtained from independent experiments are presented as the mean +/- standard

deviation; they were analyzed by the unpaired student t-test using Statview software version 5.0,

SAS Inst. INC. (Cary, NC). All experiments were done in triplicate. Differences were

considered significant at P < 0.05 level.









10) and CCR2 (Figurel 1). However, when we treated the cells with ZnPP, a competitive

inhibitor for HO-1 enzyme activity, we saw a decreased expression of MCP-1 and an increase

expression of CCR2, suggesting that HO-1 levels are directly correlated with MCP-1 expression

and inversely correlated with CCR2 expression. Previous findings have given contradicting

evidence in terms of the correlation between HO-1, MCP-1 and CCR2. In many studies, the

level of both MCP-1 mRNA and protein were reduced with the inhibition of HO-1 (34), but in

others, the opposite finding was observed (57). Zampetaki et al (45) have shown that despite

high mRNA levels, significantly lower levels of cytokine protein were found in BALF of mice

over-expressing HO-1. These findings suggest that HO-1 over-expression can suppress the

induction of cytokine mRNA levels and that this regulation might act through the NFKB

signaling pathway. Our in vitro and in vivo results, however, show that inhibiting HO-1 enzyme

activity led to a decrease in MCP-1 protein levels in cell supernates (Figure 12), BALF (Figure

27) and mouse serum (Figure 28), suggesting that HO-1 is directly correlated to MCP-1

expression in mouse monocytes. Since we observed an induction of HO-i and increased levels

of MCP-1 in the lung tissue, BALF and serum of infected HO-1 +/+ mice, it is possible that an

MCP-1 gradient was established in order to recruit monocytes from the peripheral blood to the

site of infection. This corresponds to a normal immune response in which cells expressing

CCR2 are recruited from the periphery and chemotax along an MCP-1 gradient towards the site

of insult in order to from granulomas (28). When testing MCP-1 protein levels in infected mice,

we observed higher basal levels of MCP-1 in sera and BALF in control HO-1 -/- mice as

compared to wild type controls. These results support previous findings (46) and suggest that

HO-1 -/- mice are in a chronic state of inflammation. This chronic inflammatory state could lead











8

7-

6


1 *


CL 4 hour

S8 hour

.3 24 hour

2 E48 hour

1



Control M. avium

Figure 4-3. HO-1 relative apparent gene expression significantly increases in a time dependent
manner in mouse monocytes after treatment with M. avium. HO-1 levels increase
significantly (p < .001) in cells treated with M. avium (*). RAW 264.7 cells were
treated for 4, 8, 24 and 48 hours in serum free medium (C), or with M. avium.









disseminated infection, loose, unorganized granulomas and greater pathology as compared with

their HO-1 +/+ counterparts which formed organized granulomas after infection. This is a

significant finding because we can now focus our efforts on the direct role of HO-1 in the

process of granuloma formation and cellular recruitment to the site of infection in the live

animal. Our HO-1 -/- mouse model has given us a useful tool in the study of granuloma

formation following M. avium infection. Our studies have helped shed light on the role of HO-1

in the regulation of MCP-1 and CCR2 and in the process of cellular recruitment during and

following mycobacterial infection.









MCP-1 levels in Cell Culture Supernates

To support our previous results obtained with RNA, we measured the levels of the same

cytokine in RAW 264.7 cell culture supernates using ELISA. MCP-1 levels were significantly

increased in a time dependent manner in cell culture supernates of cells that were treated with M

avium for 4, 8 and 24 hours, but these levels were abrogated after treatment with ZnPP-IX even

with concurrent infection with M avium (Figure 4-6).

In Vivo Results

Mouse tissue

After euthanasia, we checked the lungs, liver and spleen of HO-1 +/+ and HO-1 -/- mice to

ensure granuloma formation and therefore, infection has occurred. We observed that the lungs of

HO-1 +/+ and HO-1 -/- mice showed detectable differences in granuloma formation. Figure 4-8

shows that HO-1 +/+ mice infected with M avium formed granuloma in the lungs as compared

to saline controls (figure 4-7). We then examined the lungs of HO-1 -/- mice to see whether they

form similar lesions following infection with M. avium. Figure 4-10 shows that HO-1 -/- mice

inoculated with M avium do not form organized granulomas and have disseminated infection in

the lung as compared to saline controls (figure 4-9).

Immunohistochemistry

To confirm the mouse model of M avium infection, we examined the formation of

granuloma in lung tissue of infected mice. From analyzing our H&E stained tissue sections, it

was evident in HO-1+/+ mice developed granulomas after 6 months exposure to M. avium via

intra-nasal inoculation as compared to saline controls (Figure 4-11). These mice exhibited

organized granuloma formation and were able to contain the pathogen to the site of infection.

HO-1 -/- mice displayed loose, unorganized lesions in the lungs after exposure to M avium as

compared to their control counterparts (Figure 4-12).

36









4-12 A) 100x magnification H&E stain ofHO-i -/- saline control lung. B) 100x
magnification H&E stain of HO-1 -/- showing loose, unorganized granulomas and
disseminated infection in lung tissue following 6 month exposure to M. avium .............46

4-13 100x magnification of control lung from HO-1 +/+ mouse showing basal levels of
H O-1 ............. ................... ......................................................... ........ 47

4-14 200x magnification ofM. avium infected HO-1 +/+ mouse lung tissue showing
increased expression of HO-1 in granuloma............... ................47

4-15 200x magnification of granuloma in M avium infected HO-1 +/+ mouse lung
showing increased expression of HO-1 in granuloma....................................................48

4-16 A) 100x magnification of control HO-1 +/+ control lung showing basal levels of
CCR2 (brown). B) 100x magnification of HO-i -/- control mouse lung showing
basal levels of CCR2....... ................. ..................... ...... ........ 48

4-17 A) l00x magnification of an HO-1+/+ control mouse lung tissue showing basal
levels of CCR2 (brown). B) 100x magnification of an HO-1 +/+ mouse lung
inoculated with M avium for 6 months showing increased expression of CCR2.............49

4-18 A) l00x magnification of an HO-1 +/+ mouse lung after 6 months M avium
infection showing CCR2 expression (brown). B) An increase in CCR2 expression in
HO-1 -/- mouse lung after 6 months of M avium infection ...........................................49

4-19 A and B. 100x magnification of an HO-1 +/+ mouse lung after 6 month infection
with M avium showing CCR2 co-localizes with granuloma ............... ...............50

4-20 A and B. 100x magnification of an HO-1 -/- mouse lung following 6 month infection
with M avium showing disseminated expression of CCR2 ...........................................50

4-21 MCP-1 levels are significantly increased in BALF of infected HO-1 +/+ and HO-1 -
/- mice as compared with controls. ........................................ ................. 51

4-22 MCP-1 levels are increased in mouse serum after 6 month M avium infection and
are significantly higher in infected HO-1 +/+ and HO-1 -/- mice as compared with
saline controls. .......................................................52









that the ordered influx of leukocytes to the site of inflammation is controlled by different

regulatory Chemokines (26, 27). Chemokines are a large family of structurally related secreted

proteins that are important for leukocyte trafficking. These small (8-12kDa) inducible secreted

cytokine proteins act primarily as chemoattractants and activators of leukocytes (28).

Chemokines can be divided into four subfamilies (C-C, C-X-C, C, and C-X-X-X-C) depending

on spacing of highly characteristic cysteine residues within their amino terminal regions (29).

Chemokines are produced by a variety of cells, including leukocytes, epithelial cells, endothelial

cells, fibroblasts and numerous other cell types following stimulation by cytokines or microbial

products (25 30, 31). Chemokines exert their effect via a distinct group of seven-

transmembrane-domain protein receptors that signal through heterodimeric GTP-binding

proteins (29, 32).

Two important molecules involved in the recruitment of monocyte-macrophages and T-

cells to the site of infection are Monocyte chemoattractant protein-i (MCP-1) and Chemokine

receptor 2 (CCR2). MCP-1, acting through its receptor CCR2, is a potent chemoattractant for

mononuclear cells (25).

Formation Of Granuloma

Granulomas are formed as a consequence of chronic antigen persistence and are thus a

hallmark of all mycobacterial infections (32). In general, the production of pro-inflammatory

cytokines and chemokines is essential for the recruitment of inflammatory cells to the site of

infection and for the formation and maintenance of granuloma. This will not only localize and

sequester the bacteria, but will also localize the immuno-pathologic responses to the bacteria

(34). Granuloma formation involves the interaction of bacteria, fibroblasts, immune cells,

including macrophages, and T cells, as well as immune effectors such as chemokines and

cytokines (Figure 2-2). This process involves a cytokine network which drives the T-helper cell

16









CHAPTER 2
BACKGROUND

Mycobacterium

Mycobacterium is a genus of Actinobacteria, a gram positive bacterium with a high G-C

content. Mycobacteria are aerobic and non-motile. They are classified as gram positive because

they lack an outer cell membrane but they characteristically have a thick cell wall comprised of

mycolic acid or mycolates (the Latin prefix "myco" pertains to the waxy compounds in the cell

wall of these organisms). The Mycobacterial cell wall consists of a hydrophobic mycolate layer

and a peptidoglycan (PGN) layer which are held together by arabinogalactan, a polysaccharide

(1). This waxy cell wall is an essential virulence factor which contributes to the organism's

survival and gives these organisms their ability to withstand the environment and resist many

antibiotics. Mycobacteria can survive long exposure to acids, alkalis, detergents, oxidative burst,

and lysis by complement. They can also resist antibiotics that target the cell wall such as

penicillin. These organisms are widespread in the environment and typically live in water and

food sources (4).

Before the AIDS epidemic, the usual presentation ofNTM disease in immunocompetent

patients was pulmonary, confined to cervical lymph nodes, limited to skin or in rare cases,

disseminated (3). Most patients presenting this disease were older men who had previous

underlying pulmonary diseases such as chronic obstructive pulmonary disease (COPD),

bronchiectasis, previous tuberculosis and silicosis (5). Other risk factors for NTM disease

include: reduced immune competence due to cancer chemotherapy, immunosuppression involved

with transplantation, altered chest architecture, alcoholism, and smoking tobacco (4). Recent

findings, however, suggest that the occurrence of NTM disease in immunocompetent patients

with no underlying lung disease is on the rise. The major pulmonary mycobacterial pathogens









CHAPTER 3
MATERIALS AND METHODS

HO-1 Knockout Mouse Model

C57BL/6 mice were used for this model since it has previously been shown that this strain

develops focused lesions that grow into large granulomas following M. avium infection; these

granulomas exhibit central necrosis caseouss necrosis) similar to human granulomas described in

tuberculosis lesions (7). We used the HO-1 knockout model developed by Kenneth D. Poss and

Susumu Tonegawa as described (72). Briefly, the construct was designed to remove a 3.7kb

XhoI-HindIII fragment of murine DNA with intron sequence and coding sequence for the final

226 amino acids (Figure 3-1). Chimeric mice were generated as described (71, 73) and HO-1 -/-

(Hmox1-/-) were obtained by mating male chimeras with C57BL/6 females; these Hmoxl+/-

animals were intercrossed to produce Hmoxl-/- mice. HO-1 wild type (+/+), heterozygous (+/-),

and knockout (-/-) mice were maintained in a breeding colony in a specific pathogen free (SPF)

animal housing facility under Animal Care Services at the University of Florida. HO-1 -/- male

mice of 8 weeks of age were paired with heterozygous (+/-) females of the same age and

subsequent litters were genotyped for the HO-1 gene. Genotyping was done upon weaning

mouse pups 21 days after birth. Mouse tissue was obtained by cutting a small piece (1cm) off

the tip of the tail. This tissue was digested and genomic DNA was isolated using Extract-N-

AmpTM Tissue PCR Kit (Sigma, St. Louis, MO). PCR was performed using specific primers for

wild type and knockout (mutant) HO-1 genes. HO-1 Wild type primer sequence (forward, 5'-

GTA CAC TGA CTG TGG TRG GGG GAG-3', reverse, 5'- AGG GCC GAG TAG ATA TGG TAC-3')

and HO-1 mutant primer sequence (forward, 5'- GCT TGG GTG GAG AGG CTA TTC-3', reverse,

5'- CAA GGT GAG ARG ACA GGA GAT C-3'). The PCR product was run on a 2% agarose gel





























Figure 4-15. 200x magnification of granuloma in M avium infected HO-1 +/+ mouse lung
showing increased expression of HO-1 in granuloma. Blue color shows counter-stain
with Hematoxylin











A .. Br






Figure 4-16. A) 100x magnification of control HO-1 +/+ control lung showing basal levels of
CCR2 (brown). B) 100x magnification of HO-1 -/- control mouse lung showing basal
levels of CCR2 (brown). Blue color shows counter-stain with Hematoxylin
Figre4-6.A)lOx agnfiatonofcotrl H-i+1 cntollug sowngbaalleel o
CC2(ron.B)l' mgiicto ofI HO- -- conrolmueln hwn aa
leel of CCR2 (bon.Bu clrsoscune-ti it eaoyi















3500


3000 *


2500 -
**

E 2000 4 hour

8 hour
,.. 24 hour

1000 -

500


0
Control M. avium ZnPP + M. avium



Figure 4-6. MCP-1 levels significantly increase (p < .05) in cell supernates in a time dependent
manner after treatment with M avium as compared to controls (*) and are
significantly decreased (p < .05) after inhibition of HO-1 with ZnPP as compared
with M avium treatment alone (**).









Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science


HEME OXYGENASE-1 REGULATES CCR2/MCP-1 AXIS AND GRANULOMA
FORMATION IN A MOUSE MODEL OF NONTUBERCULOUS MYCOBACTERIAL
INFECTION

By

Doron Regev

August 2009

Chair: Dr. Veena Antony
Major: Medical Sciences

Non Tuberculous Mycobacterial (NTM) infections are a major cause of disease in animals

and humans around the world and have become an increasing source of infection among patients

with HIV and AIDS. Recently, there has been an increase in NTM infections in

immunocompetent patients, especially in the Southeastern United states. A hallmark of NTM

infection is the formation of granulomas which are a conglomeration of the invading pathogen

and host inflammatory cells including macrophages, T-cells, B-cells and dendritic cells.

Granulomas can contain the pathogen and protect the host from further dissemination of the

infection. Heme Oxygenase-i (HO-1) is a cytoprotective enzyme which breaks down heme.

HO-1 is induced by oxidative stress, bacterial infection and many pro-inflammatory cytokines

and has been shown to be up-regulated in granulomas and infected tissue. Monocyte

Chemotactic Protein-i (MCP-1) along with its receptor Chemokine Receptor2 (CCR2), are

responsible for the recruitment of monocytes from peripheral blood to the site of infection. Our

hypothesis is that HO-1 plays a role in the formation of organized (tight) granulomas by

regulating the expression of CCR2 and MCP-1 in monocytes and coordinating cellular

recruitment form peripheral blood to the site of infection. We have developed a mouse model of

8












450

400 -

350 -

S300 -


t 250 -

r*I
S200 -

150 -

100 -

50



Wild type Control Wild type M. avium HO-1-/- Control HO-1-/- M. avium

Mouse Sample

Figure 4-22. MCP-1 levels are increased in mouse serum after 6 month M avium infection and
are significantly higher (p < .0001) in infected HO-1 +/+ and HO-1 -/- mice (*) as
compared with saline controls. Significantly higher basal levels of MCP-1 are seen in
HO-1 -/- sera then HO-1 +/+ sera (**).









LIST OF FIGURES


Figure page

2-1 Recognition of an appropriate ligand by TLR-2..................................23

2-2 Formation of granuloma involving pathogen, macrophages, T-cells, and B cells. ...........24

2-3 Degradation of heme by HO-1 ...........................................................................25

2-4 CCR2 structure ................... ........................................... ........ ............... 25

2-5 Schematic representation of the signaling pathways activated through the CCR2.
Ligand .............................. ..................... ........ 26

3-1 Targeted disruption of the Hmoxl gene ............... .................... ....... 34

4-1 400x magnification stain of RAW 264.7 cells after 4 hours of incubation in SFM
showing basal levels of HO-1 ........................ ..... ............39

4-2 400x stain of RAW 264.7 cells after 4 hours treatment with M avium showing
increased levels of HO-1 ..... ................. ..... .... .. ...... .............. 39

4-3 HO-1 relative apparent gene expression significantly increases in a time dependent
manner in mouse monocytes after treatment with M. avium..................... ......... 40

4-4 MCP-1 Relative Gene Expression significantly increased (p < .001) in monocytes
after treatment with M. avium for 8 and 24 hours as compared to controls ...................41

4-5 CCR-2 Relative Gene Expression was significantly increased (p<.05 ) in M. avium
treated monocytes as compared with controls at 4 hours (*), 8 hours (**), and 24
hours (***) and in cells treated with ZnPP and M avium as compared to controls. .......42

4-6 MCP-1 levels significantly increase (p < .05) in cell supernates in a time dependent
manner after treatment with M avium as compared to controls...... ................ ..43

4-7 HO-1+/+ 6 month control lung ................. .... ......... .... .........44

4-8 HO-1 +/+ lung showing granuloma formation ............. .............................. 44

4-9 HO-1 -/- 6 month control lung.............. .... ......... ..... ........45

4-10 HO-1 -/- lungs showed disseminated infection and loose granuloma formation............45

4-11 A) 100x magnification H&E stain of an HO-1 +/+ control mouse lung. B) 100x
magnification H&E stain of an HO-1 +/+ mouse infected with M. avium...................46









many different cell type surfaces and provides a mechanism for specific interaction with certain

chemokines. Belperio et al. (60) have shown that CCR2-/- mice have a reduced infiltration of

mononuclear phagocytes and neutrophils in a mouse model using tracheal allografts. However,

the levels of lymphocyte infiltration were not changed and the absence of CCR2 expression did

not change the protein levels of MCP-1 (60). Additionally, it has been shown that CCR2-/- mice

showed a decreased level of recruitment of mononuclear phagocytes to the site of granulomas

(69). Other experiments have shown that the CCR2 receptor can regulate MCP-1 levels by

binding and internalizing MCP-1, creating a self-limiting negative feedback loop and abrogating

the influx of inflammatory cells to the site of injury (70). Lu et al., (71) reported that CCR2 is

probably the only receptor for MCP-1 in vivo. We believe that expression of CCR2 on

monocytes plays an integral role in granuloma formation. This receptor allows immune cells to

chemotax along an MCP-1 gradient towards the site of infection.









52. Rollins, BJ, Morrison, ED, Stiles, CD: Cloning and expression of JE, a gene inducible by
platelet derived growth factor and whose product as cytokine-like properties. Proc Natl
Acad Sci USA 1998;85:3738-3742

53. Matsushima,K, Larsen, CG, DuBois, GC, Oppenheim, JJ: Purification and
Characterization of a Novel Monocyte chemotactic and Activating Factor Produced by a
Human Myelomonocytic Cell Line. The journal of Experimental medicine; 169:1485-
1490

54. Yoshimura, T, Robinson, E, Tanaka, S, Appella, E, Leonard, E: Purification and Amino
Acid Analysis Of Two Human Monocyte Chemoattractants Produced By
Phytohemagglutinin-Stimulated Human Blood Mononuclear Leukocytes. The Journal of
Immunology 1989;142:1956-1962

55. Valente, AJ, Graves, DT, Vialle-Valentin, CE, Delgado, R, Schwartz, CJ: Purification of
a monocyte chemotactic factor secreted by nonhuman primate vascular cells in culture.
Biochemistry 1998;27:4162-4168

56. Furutani, Y, Nomura, H, Notake, M, Oyamada, Y, Fukui, T, Yamada, M, Larsen, CG,
Oppenheim-JJ, Matsushima, K: Cloning and sequencing of the cDNA for human
monocyte chemotactic and activating factor (MCAF). Biochemical and Biophysical
Research Communications 1989;159:249-255

57. Jiang, Y, Valente, AJ, Williamson, MJ, Zhang, L, Graves, DT: Post-translational
modifications of a monocyte-specific chemoattractant synthesized by glioma,
osteosarcoma, and vascular smooth muscle cells. The Journal of Biological Chemistry
1990;265:18318-18321

58. Botazzi, B, Colotta, F, Sica, A, Nobili, N, Mantovani, A: A chemoattractant expressed in
human sarcoma cells (tumor-derived chemotactic factor, TDCF) is identical to monocyte
chemoattractant protein-1/monocyte chemotactic and activating factor (MCP-1/MCAF).
International Journal of Cancer 1990;45:795-797

59. Hale-Donze, H, greenwel-Wild, T, Mizel, D, Doherty, MT, Chatterjee, D, Orenstein, JM,
Wahl, SM: Mycobacterium avium Complex Promotes Recruitment of Monocyte Hosts
for HIV-1 and Bacteria. The Journal of Immunology 2002;169:3854-3862

60. Nibbs, RJB, Graham, GJ, Pragnell, IB: Macrophage inflammatory protein 1-alpha. In
Cytokines 1998 p. 467

61. Proost, P, Wuyts, A, Opdenakker, G, Van Damme, J: Monocyte Chemotactic Protein1, 2
and 3. In Cytokines. P. 489

62. Belperio, JA, Keane, MP, Burdick, MD, Lynch, JP III, Xue, YY, Berlin, A, Ross, DJ,
Kunkel, SL, Charo, IF, Strieter, RM: Critical Role for the Chemokine MCP-1/CCR2 in
the Pathogenesis of Bronchiolitis Obliterans Syndrome. J. Clin. Invest. 2001;108:547-556









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3. Inderlied, CB, Kemper, CA, Bermudez, LEM: The Mycobacterium avium Complex.
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5. Iseman, MD, Corpe, RF, O'brien, RJ, Rosenzwieg, DY, Wolinsky, E: Disease Due to
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6. Hardy, WD, Feinberg, JD, Finkelstien, M, Power, ME, He, W, Kaczka, C, Frame, PT,
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9. Houben, ENG, Nguyen, L, Pieters, J: Interaction of pathogenic mycobacteria with the
host immune system. Current Opinions in Microbiology. 2008;9:76-85

10. Nathan, C, Xie, Q: Nitric oxide synthases: roles, toils and controls. Cell 1994; 78:915-
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Investigation of mycobacterial colonization and invasion of the respiratory mucosa.
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12. Covert, TC, Rodgers, MR, Reyes, AL, Stelma, GN: Occurrence of Nontuberculous
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13. Shin, GA, Lee, JK, Freeman, R, Cangelosi, GA: Inactivation of Mycobacterium avium
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7069









HEME OXYGENASE-1 REGULATES CCR2/MCP-1 AXIS AND GRANULOMA
FORMATION IN A MOUSE MODEL OF NONTUBERCULOUS MYCOBACTERIAL
INFECTION.




















By

DORON REGEV


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2009









immune response. Formation of granulomas is dependent on sequential release of specific

cytokines and chemokines, which activate and chemoattract T lymphocytes and monocytes, the

cellular components of granulomas. In vivo granuloma formation is induced and maintained by

various cytokines (35). It is believed that small, solid (organized) granulomas can contain the

infection and prevent further pathology, whereas, large, necrotic (loose) granulomas may lead to

the dissemination of the bacteria and cause greater infection. For this reason, the integrity of a

developing granuloma is crucial in terms of disease progression and survival. Ehlers et al., (32)

have shown that mice lacking a Tumor Necrosis Factor (TNF) receptor have granulomas that

disintegrate and cause widespread inflammatory apoptosis of both granulomas and surrounding

tissue, leading to higher mortality. Granulomas can provide antibacterial protection in host

tissue, but can also induce tissue damage and inflammation concomitantly. Thus, the outcome of

mycobacterial disease is linked to granuloma formation and maintenance of granuloma integrity

(16, 36, 37, 38). We believe that MCP-1 forms a gradient for immune cells expressing CCR2 on

their surfaces following mycobacterial infection. It is this gradient which allows immune cells

such as monocyte/macrophages, T-cells, and Dendritic cells to be recruited to the site of

infection from the peripheral blood. If this gradient is somehow lost, then the immune response

will not be effective in clearing the infection since the proper inflammatory cells will not be able

to migrate towards the injury and will cause widespread inflammation and further pathology of

the disease.

Heme Oxygenase-1 (HO-1)

Heme Oxygenase (HO) is a ubiquitously expressed protein which catalyzes the

degradation of heme to produce three catabolic byproducts: carbon monoxide (CO), Iron (Fe2+)

which is sequestered by ferritin and Biliverdin which is converted to Bilirubin by Biliverdin

reductase (39) (Figure 2-3). There are three isoforms of HO including: one inducible form, HO-

17











HO-1 Inhibition By Zinc Protoporphyrin-IX In Cell Cultures

Zinc protoporphyrin-IX (ZnPP) is a normal metabolite that is formed in trace amounts

during heme biosynthesis (75). ZnPP may regulate heme catabolism through competitive

inhibition of HO-1 enzyme activity. ZnPP is found in erythrocytes and is deposited in the spleen

along with heme where both bind HO-1. This process slows down heme degradation by HO-1.

ZnPP inhibits the enzyme activity of HO-1 but does not alter the gene and protein expression of

HO-1. Cells in culture were pretreated with 10tM ZnPP-IX (Frontier Scientific, Logan, UT) for

thirty minutes in SFM. The media is then changed to fresh SFM and the cells are exposed to

different treatments as described above and incubated for different time points. Cells are

collected, spun down and stored in RLT Lysis Buffer (10 parts RLT Lysis buffer, Qiagen

sciences, MD, USA and 1 part 2-Mercaptoethanol Bio-Rad Laboratories Inc., Hercules, CA)

for RNA isolation. Cell Supernates were also collected and stored in a -80' C freezer for

cytokine studies.

Mouse Model For M. Avium Infection

We have developed a murine model for M avium infection and chronic colonization which

leads to granuloma formation in the lungs and other tissue. C57BL/6 wild type and HO-1

knockout mice were inoculated intranasal with 7xl06 M. avium in PBS once per week for three

weeks. Alternatively, wild type control mice were inoculated with equal volume of PBS. Throat

swabs were done once a month and plated on M. avium-specific plates to monitor colonization.

The swabs were plated on the aforementioned 7H10 plates (BD) and incubated for 14 days in a

370 C incubator with 95% 02 and 5% C02. Colonies are visualized and counted on each plate

to determine the level of colonization in each mouse. The mice were sacrificed at different time









The supernatant was aliquoted and stored in a -80' C freezer until further use. The BAL cell

pellet was stored in Cell Freezing Medium (Sigma, St. Louis, MO) and stored in a -80' C

freezer.

Tissue Harvest

We collected the lungs, liver, spleen and kidneys from each mouse following euthanasia.

Some tissue was frozen in Optimal Cutting Temperature (OCT) compound (Sakura, Torrance,

CA) and stored in -80' C. The rest was fixed in 4% Paraformaldehyde and stored in room

temperature for 24 hours. This tissue was then transferred to 70% ethanol and stored at room

temperature until used.

Immunohistochemistry

Lung tissue from sacrificed mice was fixed in 4% Paraformaldehyde for 24 hours then

transferred to 70% Ethanol. Tissue was sent for paraffin embedding and Hematoxylin and Eosin

(H&E) staining to Histology Tech Services, Gainesville Florida. Paraffin-embedded slides were

stained for CCR2 using Goat anti mouse primary antibody (Capralogics, Hardwick, MA) and

ABC staining kit (Vector laboratories, Burlingame, CA) according to manufacturer

recommendations. Alternatively, slides were stained with primary antibody for HO-1

(Calbiochem, San Diego, CA). Briefly, the slides were de-paraffinzed using Xylenes (Fisher

Scientific, Fairlawn, NJ). Slides were placed in Xylene solution for 5 minutes twice. The slides

were then washed with IX Phosphate Buffered Saline (PBS) for 2 minutes. Next, the slides were

permeated by incubating with triton X 100 (Sigma Aldrich, St. Louis, MO) for 10 minutes and

incubated with Hydrogen Peroxide for (H202) for 30 minutes. Normal goat serum (ABC kit) was

then added for 30 minutes to block tissue from background or non-specific binding. Primary

antibody for CCR2 was added to slides for 1 hour followed by washing and addition of

secondary antibody (ABC kit) for 30 minutes. The slides were them incubated for 5 minutes in

29










MCP-1 relative gene expression in RAW 264.7 cells........................35
.CCR2 relative gene expression in RAW 264.7 cells................................ ......35
M CP-1 levels in Cell Culture Supernates....................... ............................. .......... 36
In Vivo Results ...................................................... ........ 36
M house tissue ......................................................... ................36
Immunohistochemistry ...................... ........................................ ........ 36
HO-1 protein expression in mouse lung tissue............................................................ 37
CCR2 expression in mouse lung tissue ............................... ...............37
MCP-1 levels in BALF and serum ........................................... ...............38

5 DISCUSSION .......................... .... ... ............... .53

6 FUTURE CON SIDERATION S .................................................. ............... 57

REFERENCES ................................................. .........58

BIOGRAPHICAL SKETCH .................. ......... .................. 65











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activation initiates the JAK/STAT pathway and enables efficient G protein coupling
to CCR2. G proteins mediate signaling cascades through GRK and arrestins, leading
to receptor desensitization and internalization. Other signaling molecules triggered
through CCR2 include PI-3 kinase, PLC, and MAPK (apresslp.gvpi.net)


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inoculated with M. avium for 6 months showing increased expression of CCR2
(brown). Blue color shows counter-stain with Hematoxylin




















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Figure 4-18. A) 100x magnification of an HO-1 +/+ mouse lung after 6 months M avium
infection showing CCR2 expression (brown). B) An increase in CCR2 expression in
HO-1 -/- mouse lung after 6 months of M avium infection. Blue color shows counter-
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vector. A 3.7-kb region including exons 3, 4 and a portion of 5 (e3-e5) was replaced
with a pkg-neo cassette. The 5' and 3' probes used for screening ES cell clones and
genotyping mice are shown. The 5' probe hybridizes to an 11-kb KpnI fragment of
the native Hmoxl gene and a 6.5-kb fragment from the disrupted gene. D, HindIII
site; K, Kpnl; X, Xhol; Xb, Xbal. (Poss, Tonegawa, 1997).


Wild-tyl




Full Text

PAGE 1

1 HEME OXYGENASE 1 REGULATES CCR2/MCP 1 AXIS AND GRANULOMA FORMATION IN A MOUSE MODEL OF NONTUBERCULOUS MYCOBACTERIAL INFECTION. By DORON REGEV A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2009

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2 2009 Doron Regev

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3 ACKNOWLEDGMENTS I would like to acknowledge Dr. Veena Antony and especially thank her for her guidance in my research and my writing. I would also like to thank the other members of my committee, Dr. Henry Baker and Dr. Reuben Ramphal for all the input they provided. Thanks to Dr. Ana Montes Worboys and Dr. Yimu Lai for their continued help and technical assistance in the lab and thanks to Edward Hensel for showing me the clinical aspects of medical research I would like to thank Dr, Kamal Mohammed and Dr. Nasreen Najmunnisa for their help and guidance along the way. Finally, I am grateful to my parents Michael and Dalia and my siste r, Dana for their support and inspiration throughout my life

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4 TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................3 LIST OF FIGURES .........................................................................................................................6 ABSTRACT .....................................................................................................................................8 CHAPTER 1 INTRODUCTION ..................................................................................................................10 Hypothesis ..............................................................................................................................11 Objective .................................................................................................................................11 2 BACKGROUND ....................................................................................................................12 Mycobacterium .......................................................................................................................12 Mycobacterium Avium ............................................................................................................13 Mycobacterium Avium Complex (MAC) ................................................................................14 Host Response To Infection ....................................................................................................15 Formation Of Granuloma .......................................................................................................16 Heme Oxygenase1 (HO 1) ....................................................................................................17 Monocyte Chemoattractant Protein1 (MCP 1) .....................................................................19 Chemokine (C C Motif) Receptor 2 (CCR2) .........................................................................21 3 MATERIALS AND METHODS ...........................................................................................27 HO1 Knockout Mouse Model ...............................................................................................27 M. Avium culture .....................................................................................................................28 Collection Of Se rum ...............................................................................................................28 Bronchial Alveolar Lavage Fluids (BALF) ............................................................................28 Tissue Harvest ........................................................................................................................29 Immunohistochemistry ...........................................................................................................29 TIB 71 (RAW 264.7) Cells ....................................................................................................30 Co Culture of RAW 264.7 Cells With M. Avium ..................................................................30 HO1 Inhibition By Zinc ProtoporphyrinIX In Cell Cultures ...............................................31 Mouse Model For M. Avium Infection ...................................................................................31 Cytokine Studies .....................................................................................................................32 Real Time Polymerase Chain Reaction (RT PCR) Analysis .................................................32 Statistical Analysis ..................................................................................................................33 4 RESULTS ...............................................................................................................................35 In Vitro Results .......................................................................................................................35 HO1 is induced by M. avium in RAW 264.7 cells .........................................................35

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5 MCP 1 relative gene expression in RAW 264.7 cells .....................................................35 .CCR2 relative gene expression in RAW 264.7 cells .....................................................35 MCP 1 levels in Cell Culture Supernates ........................................................................36 In Vivo Results .......................................................................................................................36 Mouse tissue ....................................................................................................................36 Immunohistochemistry ....................................................................................................36 HO1 protein expression in mouse lung tissue ................................................................37 CCR2 expression in mouse lung tissue ...........................................................................37 MCP 1 levels in BALF and serum ..................................................................................38 5 DISCUSSION .........................................................................................................................53 6 FUTURE CONSIDERATIONS .............................................................................................57 REFERENCES ..............................................................................................................................58 BIOGRAPHICAL SKETCH .........................................................................................................65

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6 LIST OF FIGURES Figure page 21 Recognition of an appropriate ligand by TLR 2 ................................................................23 22 Formation of granuloma involving pathogen, macrophages, T cells, and B cells. ...........24 23 Degradation of heme by HO 1 ...........................................................................................25 24 CCR2 structure ..................................................................................................................25 25 Schematic representation of the signaling pathways activated through the CCR2. Ligand ................................................................................................................................26 31 Targeted disruption of the Hmox1 gene ...........................................................................34 41 400x magnification stain of RAW 264.7 cells after 4 hours of incubation in SFM showing basal levels of HO 1 ............................................................................................39 42 400x stain of RAW 264.7 cells after 4 hours treatment with M. avium showing increased levels of HO 1 ....................................................................................................39 43 HO1 relative apparent gene expression significantly increases in a time dependent manner in mouse monocytes after treatment with M. avium.............................................40 44 MCP 1 Relative Gene Expression significantly increased (p < .001) in monocytes after treatment with M. avium for 8 and 24 hours as compared to controls ......................41 45 CCR2 Relative Gene Expression was significantly increased (p<.05 ) in M. avium treated monocytes as compared with controls at 4 hours (*), 8 hours (**), and 24 hours (***) and in cells treated with ZnPP and M. avium as compared to controls. .......42 46 MCP 1 levels significantly increase (p < .05) in cell supernates in a time dependent manner after treatment with M. avium as compared to controls ........................................43 47 HO1+/+ 6 month control lung ..........................................................................................44 48 HO1 +/+ lung showing granuloma formation ..................................................................44 49 HO1 / 6 month control lung ...........................................................................................45 410 HO1 / lungs showed disseminated infection and loose granuloma formation ...............45 411 A) 100x magnifi cation H&E stain of an HO 1 +/+ control mouse lung. B) 100x magnification H&E stain of an HO 1 +/+ mouse infected with M. avium ......................46

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7 412 A) 100x magnification H&E stain of HO 1 / saline control lung. B) 100x magnification H&E stain of HO 1 / showing loose, unorganized granulomas and disseminated infection in lung tissue following 6 month exposure to M. avium ..............46 413 100x magnification of control lung from HO 1 +/+ mouse showing basal levels of HO1 ..................................................................................................................................47 414 200x magnification of M. avium infected HO 1 +/+ mouse lung tissue showing incr eased expression of HO 1 in granuloma ......................................................................47 415 200x magnification of granuloma in M. avium infected HO 1 +/+ mouse lung showing increased expression of HO 1 in granuloma .......................................................48 416 A) 100x magnification of control HO 1 +/+ control lung showing basal levels of CCR2 (brown). B) 100x magnification of HO 1 / control mouse lung showing basal levels of CCR2 ..........................................................................................................48 417 A) 100x magnification of an HO 1+/+ control mouse lung tissue showing basal levels of CCR2 (brown). B) 100x magnification of an HO 1 +/+ mouse lung inoculated with M. avium for 6 months showing increased expression of CCR2 .............49 418 A) 100x magnification of an HO 1 +/+ mouse lung after 6 months M. avium infection showing CCR2 expression (brown). B) An increase in CCR2 expression in HO1 / mouse lung after 6 months of M. avium infection ..............................................49 419 A and B. 100x magnification of an HO 1 +/+ mouse lung after 6 month infection with M. avium showing CCR2 co localizes with granuloma ............................................50 420 A and B. 100x magnification of an HO 1 / mouse lung following 6 month infection with M. avium showing disseminated expression of CCR2 ..............................................50 421 MCP 1 levels are significantly increased in BALF of infected HO 1 +/+ and HO 1 / mice as compared with controls ....................................................................................51 422 MCP 1 levels are increased in mouse serum after 6 month M. avium infecti on and are significantly higher in infe cted HO 1 +/ + and HO 1 / mice as compared with saline controls. ...................................................................................................................52

PAGE 8

8 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science HEME OXYGENASE 1 REGULATES CCR2/MCP 1 AXIS AND GRANULOMA FORMATION IN A MOUSE MODEL OF NONTUBERCUL OUS MYCOBACTERIAL INFECTION By Doron Regev August 2009 Chair: Dr. Veena Antony Major: Medical Sciences Non Tuberculous M ycobacterial (NTM) infections are a major cause of disease in animals and humans around the world and have become an increasing source of infection among patients with HIV and AIDS. Recently, there has been an increase in NTM infections in immunocompetent patients, especially in the Southeastern United states A hallmark of NTM infection is the formation of granulomas which are a conglomeration of the invading pathogen and host inflammatory cells including macrophages, T cells, B cells and dendritic cells. Granulomas can contain the pathogen and protect the host from further dissemination of the infection. Heme Oxygenase1 (HO1) is a cytoprotective enzyme which breaks down heme. HO1 is induced by oxidative stress, bacterial infection and many pro inflammatory cytokines and has been shown to be upregulated in granulomas and infected tissue. Monocyte Chemotactic Protein 1 (MCP 1) along with its receptor Chemokine Receptor2 (CCR2), are responsible for the re cruitment of monocytes from peripheral blood to the site of infection. Our hypothesis is that HO 1 plays a role in the formation of organized (tight) granulomas by regulating the expression of CCR2 and MCP 1 in monocytes and coordinating cellular recruitme nt form peripheral blood to the site of infe ction. We have developed a mouse model of

PAGE 9

9 Mycobacterium avium infection in both HO 1 +/+ and HO 1 / mice to test whether the lack of HO1 expression results in the formation of unorganized (loose) granulomas a nd to test whether HO1 regulates MCP 1 and CCR2 in this disease model.

PAGE 10

10 CHAPTER 1 INTRODUCTION Non Tuberculous Mycobacteria (NTM) are a group of Mycobacteria that are not members of the Mycobacterium tuberculosis complex. NTM are a major cause of opportunistic infection in immunocompromised and healthy hosts. These organisms can cause disease in animals and humans and have become an increasing source of infection among patients infected with Human Immunodeficiency Virus (HIV) or Acquired Immune Deficiency Syndrome (AIDS) (1) Mycobacterium avium complex (MAC) is the most common disseminated bacteria l infection in untreated patients with AIDS. A hallmark of disseminated MAC infections is the formation of granulomas in multiple organs including the liver, spleen, lymph nodes, bone marrow, and lung (1). Granulomas are lesions in tissue that are formed by the aggregation of activated macrophages, T cells and fibroblasts and are considered a defense mechanism against invading pathogens. Importantly, bacteria are not always eliminated within the granuloma, but can become dormant, resulting in a latent inf ection (2). In disseminated mycobacterial disease, the function and structure of granulomas are either absent or compromised. This leads to a failure of the host defenses to contain the bacte rium and to further pathology. Our current study aims to eluci date the role of Heme Oxygenase1 (HO1), a cytoprotective enzyme, in the formation of organized granulomas. Specifically, we are looking at the role of HO 1 in the regulation of two cytokines, Chemokine Receptor 2 (CCR2) and Monocyte Chemoattractant Prot ein 1 (MCP 1) both of which are responsible for the recruitment of inflammatory cells to the site of infection. Recruitment of immune cells to the site of infection is a vital step in granuloma formation and if the process is inhibited or altered, the Myc obacterial infection may not be contained.

PAGE 11

11 Hypothesis Our hypothesis was that HO 1 plays a key role in granuloma formation following mycobacterial infection by regulating the expression of CCR2 and MCP 1 in mouse monocytes, therefore, influencing the recr uitment of these inflammatory cells to the site of injury. In HO 1 +/+ mice, we expected to find high levels of MCP 1 in the lung following infection with M. avium creating a gradient for chemotaxis of immune cells from the periphery to the site of injury In HO 1 / mice, in which the HO 1 gene was mutated and knocked out, we expected to see high levels of MCP 1 and CCR2 in the periphery as well as in the lung following infection with M. avium ., therefore, causing the gradient for chemotaxis to be distur bed and inflammation to be disseminated. Objective Our objective was to develop a murine model of M. avium infection and granuloma formation in order to elucidate the role of HO 1 and its regulation of MCP 1 and CCR2 in mouse monocytes.

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12 CHAPTER 2 BACKGROUND Mycobacterium Mycobacterium is a genus of Actinobacteria, a gram positive bacterium with a high G C content. Mycobacteria are aerobic and non motile. They are classified as gram positive because they lack an outer cell membrane but they characterist ically have a thick cell wall comprised of mycolic acid or mycolates (the Latin prefix myco pertains to the waxy compounds in the cell wall of these organisms). The Mycobacterial cell wall consists of a hydrophobic mycolate layer and a peptidoglycan (PGN ) layer which are held together by arabinogalactan, a polysaccharide ( 1). This waxy cell wall is an essential virulence factor which contributes to the organisms survival and gives these organisms their ability to withstand the environment and resist man y antibiotics. Mycobacteria can survive long exposure to acids, alkalis, detergents, oxidative burst, and lysis by complement. They can also resist antibiotics that target the cell wall such as penicillin. These organisms are widespread in the environme nt and typically live in water and food sources ( 4). Before the AIDS epidemic, the usual presentation of NTM disease in immunocompetent patients was pulmonary, confined to cervical lymph nodes, limited to skin or in rare cases, disseminated ( 3). Most pati ents presenting this disease were older men who had previous underlying pulmonary diseases such as chronic obstructive pulmonary disease (COPD), bronchiectasis, previous tuberculosis and silicosis ( 5). Other risk factors for NTM disease include: reduced im mune competence due to cancer chemotherapy, immunosuppression involved with transplantation, altered chest architecture, alcohol ism, and smoking tobacco (4). Recent findings, however, suggest that the occurrence of NTM disease in immunocompetent patients with no underlying lung disease is on the rise. The major pulmonary mycobacterial pathogens

PAGE 13

13 are: Mycobacterium avium ( M. avium ), Mycobacterium kansasii ( M. kansasii ) and Mycobacterium intracellulare ( M. intracellulare ) There is little evidence of person to person spread of NTM and it is believed that the environment is the main source or reservoir for these organisms. NTM disease in AIDS is caused primarily by M. avium and is second only to AIDS wasting syndrome as t he most common cause of death in these patients ( 6 ). Mycobacterium Avium M. avium is a nontuberculous mycobacterium which infects humans and animals alike. M. avium is an opportunistic infectious agent that mostly affects patients with underlying condi tions that compromise local or systemic immunity ( 7) and has become a major human pathogen, primarily due to the emergence of the AIDS epidemic. This mycobacterium is found in the environment, particularly in water sources and is in close contact with huma n populations (7). Human infection is believed to be initiated either through the intestinal tract or by the inhalation of aerosols containing bacteria (7). When inhaled, M. avium enters the body via the respiratory route through aerosols and the first host cells to encounter the pathogen are bronchial epithelial cells and alveolar macrophages ( 7). Mycobacteria use different receptors to gain access into macrophages: mannose receptors, complement receptors (CR3), type A Scavenger receptors and in exposed hosts with mycobacteria 7, 8 ). M. avium can spread from the initial site of infection to the rest of the body through the lymphatics or through the blood. At the main site of infection, the bacilli are phagocytosed b y alveolar macrophages (4). This is the first event in which the host develops a response to the invading pathogen and is vital to the outcome of infection. Of the many virulence factors of Mycobacteria, their ability to reside and multiply within alveol ar macrophages is seen as one of the most important. Other virulence factors of NTM are: prevention of acidification of phagocytic vesicles, prevention of phagosomes lysosome fusion, delay in tumor necrosis factor

PAGE 14

14 secretion by infected host cells, uptake b y epithelial cells and production of receptors for macrophage binding ( 9). Phagocytosed pathogens are normally transported from the phagosomes to lysosomes within the macrophages and are effectively destroyed after phago lysosomal fusion. The most well c haracterized antimicrobial mechanisms of the macrophage are the ones that involve oxidative damage: the respiratory burst and nitric oxide (NO) production ( 9). These tw o systems work synergistically in killing many microbes (7, 10). Macrophages that have phagocytosed the bacilli normally die and form a central area of necrosis or a caseum; the pathogen is then contained withi n these caseous granulomas (11). Mycobacterium Avium C omplex (MAC ) Mycobacterium avium complex (MAC) is generally referred to as an opportunistic pathogen since it usually infects patients with established lung damage ( 11). Mycobacteria included in the MAC family are classified as acid fast, slowly growing bacilli that may produce a yellow pigment in the absence of light (1). Other species of Mycobacteria which are included in MAC include: M. avium paratuberculosis M. avium silvaticum M. avium hominissuis and M. avium colombiense ( 3). MAC in AIDS patients most often causes a disseminate d illness (bacteria is spread though the blood stream) and can cause many symptoms throughout the body. The risk of MAC is inversely related to the patients CD4 + T cell count, and increases significa ntly when the CD4+ T cell count decreases below 50 cells/mm3 of blood (3). 98% of MAC infections in AIDS patients are due to M. avium ( 1). Isolates from MAC infected patients are commonly referred to as Mycobacterium avium hominissuis since this strain is found mostly in humans. Like most NTM, MAC bacteria are found in air, water, soil, foods, some tobacco products, and in many animals. Covert et al showed that personto person transmission of MAC bacteria is unlikely, suggesting that humans contract this disease from the environment ( 12). Recently, there has been a growing concern about human exposure to MAC through drinking

PAGE 15

15 water due to its high r esistance to most chemical disinfectants in water treatment processes and its high prevalence in biofilms in water distribution systems (13 14, 15). Because most Mycobacteria are intracellular pathogens, the host cells, alveolar macrophages (AM) in this case, can actually serve as a barrier to the delivery of drugs to the intracellular environment ( 16). MAC organisms have shown to have resistance to many antimycobacterial drugs, which adds to the challenges of treating this disease. Host Response To Infec tion After mycobacterial infection, the innate and adaptive immune systems respond with the recruitment of immune cells to the site of injury. The bacilli are recognized by host immune cells via Toll Like Receptor (TLR) 2 ligation ( 17). TLRs are pattern r ecognition receptors (PRRs) which recognize and bind to mycobacterial cell wall components and other pathogenic materials. TLRs are believed to represent key receptors for the recognition of mycobacterial antigens and activation of macrophages and Dendriti c cells (DC), as well as other cells of innate immunity, thereby likely modulating the adaptive immune response (15,17,19). A variety of microbial products recognize and activate mammalian TLRs, facilitating the transcription of genes involved in regulati ng the adaptive immune response, including chemokines, cytokines and co stimulatory molecules (15, 20,21,22) Mammalian TLRs represent a structurally conserved family of membrane receptors, which have homology t o the Drosophila Toll system (17, 20) TLR s ignaling leads to the nuclear translocation of the transcription factor nuclear factor 2the expression of many immune response genes, such as those encoding cytokine s. TLR signaling also triggers differentiation of monocytes into macrophages and dendritic cells allowing for a more potent innate and adaptive immune response (9, 24) Cytokines are likely to be important mediators during the pulmonary inflammatory resp onse ( 25). It is also believed

PAGE 16

16 that the ordered influx of leukocytes to the site of inflammation is controlled by different regulatory Chemokines ( 26, 27). Chemokines are a large family of structurally related secreted proteins that are important for leukocyte trafficking. These small (8 12kDa) inducible secreted cytokine proteins act primarily as chemoattractants and activators of leukocytes ( 28) Chemokines can be divided into four subfamilies (C C, C X C, C, and C X X X C) depending on spacing of highly characteristic cysteine residues within their amino terminal regions ( 29 ). Chemokines are produced by a variety of cells, including leukocytes, epithelial cells, en dothelial cells, fibroblasts and numerous other cell types following stimulation by cytokines or microbial products ( 25 30, 31). Chemokines exert their effect via a distinct group of seventransmembrane domain protein receptors that signal through heterodimeric GTP binding proteins ( 29, 32). Two important molecules involved in the recruitment of monocyte macrophages and T cells to the site of infection are Monocyte chemoattractant protein 1 (MCP 1) and Chemokine receptor 2 (CCR2). MCP 1, acting through i ts receptor CCR2, is a potent chemoattractant for mononuclear cells (25). Formation Of Granuloma Granulomas are formed as a consequence of chronic antigen persistence and are thus a hallmark of all mycobacterial infections ( 32). In general, the producti on of proinflammator y cytokines and chemokines is essential for the recruitment of inflammatory cells to the site of infection and for the formation and maintenance of granuloma. This will not only localize and sequester the bacteria, but will also localize the immunopathologic responses to the bacteria ( 34). Granuloma formation involves the interaction of bacteria, fibroblasts, immune cells, including macrophages, and T cells, as well as immune effectors such as chemokines and cytokines (Figure 22). T his process involves a cytokine network which drives the T helper cell

PAGE 17

17 immune response. Formation of granulomas is dependent on sequential release of specific cytokines and chemokines, which activate and chemoattract T lymphocytes and monocytes, the cellu lar components of granulomas. In vivo granuloma formation is induced and maintained by various cytokines (35) It is believed that small, solid (organized) granulomas can contain the infection and prevent further pathology, whereas, large, necrotic (loose ) granulomas may lead to the dissemination of the bacteria and cause greater infection. For this reason, the integrity of a developing granuloma is crucial in terms of disease progression and survival. Ehlers et al., (32) have shown that mice lacking a Tumor Necrosis Factor (TNF) receptor have granulomas that disintegrate and cause widespread inflammatory apoptosis of both granulomas and surrounding tissue, leading to higher mortality. Granulomas can provide antibacterial protection in host tissue, but can also induce tissue damage and inflammation concomitantly. Thus, the outcome of mycobacterial disease is linked to granuloma formation and maintenance of granuloma integrity (16 36, 37, 38). We believe that MCP 1 forms a gradient for immune cells expressing CCR2 on their surfaces following mycobacterial infection. It is this gradient which allows immune cells such as monocyte/macrophages, T cells, and Dendritic cells to be recruited to th e site of infection from the peripheral blood. If this gradient is somehow lost, then the immune response will not be effective in clearing the infection since the proper inflammatory cells will not be able to migrate towards the injury and will cause wide spread inflammation and further pathology of the disease. Heme Oxygenase 1 (HO 1) Heme Oxygenase (HO) is a ubiquitously expressed protein which catalyzes the degradation of heme to produce three catabolic byproducts: carbon monoxide (CO), Iron (Fe2+) which is sequestered by ferritin and Biliverdin which is converted to Bilirubin by Biliverdin reductase ( 39) (Figure 23). There are three isoforms of HO including: one inducible form, HO -

PAGE 18

18 1, and two constitutive forms, HO 2 and HO 3 ( 40 ). Also known as H eat Shock protein 32 (HSP32), HO 1 is the rate limiting enzyme involved in the degradation of heme, a potent oxidant. In addition to its role as a key enzyme in heme degradation, HO 1 has been shown to be anti inflammatory and antioxidative through its br eakdown of heme ( 41). HO1 is a 32 kDa microsomal stress response protein that is induced by oxidative stress, inflammation and bacterial infection and is secreted by many cell types (41). Mitzuno et al. (41) have shown that among peripheral blood leukoc ytes, monocytes are the principal source of HO 1 when stimulated in vitro and that his production plays a role in systemic inflammation. HO 1 has been shown to be induced by glutathione depletion, lipopolysaccharide (LPS) and both hyperoxia and hypoxia in vivo ( 42). In addition, HO 1 is induced by various cytokines and growth factors ( 43 ). The 5'flanking region of the HO 1 gene contains binding sites for the transcription factors that regulate inflammation, including nuclear factor kappa B and activator protein 1(74). However, these do not appear to mediate lipopolysaccharide induced HO 1 gene expression. This transcription factor may also be important in the regulation of HO 1 by proinflammatory stimuli ( 44). HO 1 plays a central role in the defense a gainst oxidative and inflammatory insults in the lung and has been shown to be upregulated in many pulmonary diseases ( 45). HO1 deficiency, however, is associated with chronic inflammation and increased leukocyte recruitment in mice and in humans ( 41). Zampetaki et al ( 46) have shown that HO 1 deficiency in humans and mice results in chronic inflammation and increased leukocyte recruitment. The byproducts of HO 1 enzymatic activity are cyto protective, anti inflammatory and may act as antioxidants at t he right concentrations (44) HO1 has been implicated in the protection of lung tissue during oxidative stress, but the expression and cellular distribution of HO 1 is poorly characterized. In healthy lung tissue, HO 1 has been shown to be expressed in alveolar macrophages and in

PAGE 19

19 bronchial epithelial cells ( 46). HO1 is recognized to alter both chemokine production as well as chemokine receptor expression (74) Recruitment of monocytes to the site of infection is a complex phenomenon dependant on the ex pression of chemokines and expression of receptors for these chemokines on peripheral blood monocytes. HO 1 has been shown to act in cell mediated immunity in the pleura and infections with M. avium have been shown to increase the expression of HO 1 in mononuclear cells and pleural mesothelial cells ( 47) HO1 has been shown to downregulate the inflammatory response in the lungs by attenuating the expression of adhesion molecules and inhibiting the recruitment of leukocytes or by repressing the induction of cytokines and c hemokines such as MCP 1 (47). It is not known how HO 1 regulates and suppresses cytokine expression. It is possible that HO therefore abrogates an inflammatory response (45). HO 1 has been shown to dir ectly regulate MCP 1 mRNA expression trough the degradation of heme ( 48) Furthermore, HO 1 induction results in suppression of monocyte chemotactic response via inhibition of CCR2 expression ( 49). Monocyt e Chemoattractant Protein 1 (MCP 1) MCP 1 (Also known as monocyte chemotactic and activating factor (MCAF)) is a 76 amino acid peptide that is selectively chemotactic for peripheral blood monocytes ( 50). MCP 1 is an 8.7kDa protein that has specific chemoattractant and activating activity for monocytes in acute inflammatory conditions (25).The regulated interactions of chemokines with their respective receptors are thought to mediate the controlled recruitment of specific leukocyte subpopulations required during host defense and inflammation. MCP 1, a member of the CC motif chemokine family, is secreted by pleural mesothelial cells, endothelial cells, fibroblasts, monocytes, macrophages and leukocytes in response to inflammatory signals such as IL 1 and TNF alpha and bacterial infection ( 51). CC chemoki nes have two conserved, adjacent cysteines near their amino terminus and are predominantly chemotactic for mononuclear cells (65) MCP -

PAGE 20

20 1 is a primary and specific mononuclear cell chemoattractant from a class of cytokines that are referred to as the plate let factor 4 (PF4) super family and are related by predicted primary structural similarities and by cons ervation of a 4 cysteine motif ( 51) MCP 1 was first cloned from mouse fibroblasts as a PDGF inducible gene termed JE (24,52) and is homologous to huma n MCP 1 (24, 53, 54, 55, 5 Previous results show that MCP 1, along with several othe r chemokines, is controlled by 58, 59, 60). MCP 1 creates a gradient for chemotaxis of monocytes macrophages, T cells and natural killer (NK) cells towards the site of infection and is the ligand for CCR2 which is expressed on cell surfaces of leukocytes ( 28). This receptor chemokine interaction has been shown to induce haptotaxis (the migration of cells along the gradient of substratebound attractant molecules) in mesothelial cells ( 28). MCP 1 is characterized by its ability to evoke chemotaxis mainly in monocytes (50). MCP 1 has also been shown to aid in the recruitment of other mononuclear phagocytes such as: CD45ARO+ T lymphocytes, B cells, and NK cells ( 61). In vitro, MCP 1 is chem otactic for mononuclear cells, but not Neutrophils ( 62). However, Neutrophils in an inflammatory milieu, can express CCR2, potentially enabling their chemotaxis to MCP 1 ( 63). The association between augmented levels of MCP 1 and the recruitment of mononuclear cells expressing CCR2 plays a crucial role during chronic inflammatory disease ( 62) MCP 1 has been shown to be upregulated in HO 1 knockout mice ( 64). This suggests a possible inhibitory effect by HO 1 on MCP 1. Alternatively, 6,57). It has been shown that increased levels of MCP 1 following bacterial infection correlate with the influx of CD4+ T cells and macrophages in to the lungs ( 25) However, other results suggest that MCP 1 is a mediator of inf lammation and can specifically stimulate the directional migration of T cells as well as monocytes and may play an important role in immune cell recruitment into sites of antigenic challenge (47).

PAGE 21

21 Kanakiriya et al ( 65) have shown that inhibition of HO 1 with Zinc protoporphyrin (ZnPP), a specific HO 1 inhibitor, prevented the hemininduced expression of MCP 1 mRNA and that the active form of Iron can also induce the expression of both HO 1 and MCP 1 (45). During infe ction and inflammatory disease, the increased release of MCP 1 attracts T lymphocytes and macrophages to the site of infection and results in granuloma formation (54). ZnPP prevented the expression of MCP 1 by hemin at 6 hours; examination at later time p oints demonstrate an increasing level of expression of MCP 1 mRNA despite the continued presence of this inhibitor of HO activity; indeed, at 18 hours the level of expression of MCP 1 was increased almost threefold in the presence of ZnPP (47). Thus, MCP 1 can also be induced by HO 1 independent pathways, but this leads to a delayed expression of the chemokine (47). It is believed that MCP 1 plays a crucial role in the development of disseminated MAC disease. Some studies have shown that MCP 1 can act as a negative regulator for the CCR 2 cell surface receptor ( 66). Chemo kine (C C Motif) Receptor 2 (CCR 2) CCR2 is a seven transmembrane spanning G protein coupled receptor expressed on the cell surface of leukocytes ( 60) (Figure 2 4). This receptor binds MC P 1 with high affinity and is activated upon ligand binding ( 60) MCP 1 interacts with CCR2 which has two isoforms, CCR2A and CCR2B ( 29, 68). Activation of CCR2 leads to downstream activation of Phospholipase C (PLC) which cleaves the molecule Phosphotid yl inositol (4, 5) bisphosphate (PIP2) (68). This cleavage forms two second messenger molecules called Inositol trisphospahte (IP3) and Diacylglycerol (DAG) which induce intracellular signaling events and trigger inflammation (68) Specifically, DAG has been shown to activate Protein Kinase C (PKC) and IP3 has been shown to trigger the release of calcium from internal cellular stores (60) These events promote the activation of the Mitogen Activated Protein Kinase (MAPK) pathway and induce differentiation and chemotaxis of leukocytes (60) (Figure 2 5). CCR2 is expressed on

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22 many different cell type surfaces and provides a mechanism for specific interaction with certain chemokines. Belperio et al. (60) have shown that CCR2/ mice have a reduced infiltration of mononuclear phagocytes and neutrophils in a mouse model using tracheal allograft s However, the levels of lymphocyte infiltration were not changed and the absence of CCR2 expression did not chan ge the protein levels of MCP 1 (60) Additionally, it has been shown that CCR2/ mice showed a decreased level of recruitment of mononuclear phagocytes to the site of granulomas ( 69). Other experiments have shown that the CCR2 receptor can regulate MCP 1 levels by binding and internalizing MCP 1, creating a self limiting negative feedback loop and abrogating the influx of inflammatory cells to the site of injury (70). Lu et al., ( 7 1) reported that CCR2 is probably the only receptor for MCP 1 in vivo. We believe that expression of CCR2 on monocytes plays an integral role in granuloma formation. This receptor al lows immune cells to chemotax along an MCP 1 gradient towards the site of infection.

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23 Figure 2 1. Recognition of an appropriate ligand by TLR 2 (for example, lipopolysaccharide) triggers the Tolllike receptor to recruit MyD88. MyD88 interacts with the Toll like receptor through its own Toll/IL 1 receptor domain and in turn engages the serine threonine kinase IRAK though a death domain. Signal transduction factors such as TRAF6 carry the signal through a series of phosphorylations until NF B is ultimately released to the nucleus where it can activate the transcription of appropriate immune response genes. Allan Genome Biology 2000 1 :reports0079 doi:10.1186/gb2000 16reports0079

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24 Figure 2 2. Formation of granuloma involving pathogen, macrophages, T cells, and B cells.

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25 Figure 2 3. Degradation of heme by HO 1. HO 1 catalyzes heme degradation to biliverdinIX, CO, and iron. These metabolites mediate the antiapoptotic, antiinflammatory, vasodilatory, anticoagulant, antioxidant, and antiproliferative properties of HO 1 (Fredenburgh et. al). Figure 2 4. CCR2 structure. Regions implicated in ligand binding, coupling of effector molecules and suggested targets for GRK and JAK are highlighted. ( apresslp.gvpi.net)

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26 Figure 2 5. Schematic representation of the signaling pathways activated through the CCR2. Ligand binding to CCR2 induces conformational changes in the receptor, leading to its dimerization; this in turns disables JAK2 association and activation. JAK activation initiates the JAK/STAT pathway and enables efficient G protein coupling to CCR2. G proteins mediate signaling cascades through GRK and arrestins, leading to receptor desensitization and internalization. Other signaling molecules triggered through CCR2 include PI 3 kinase, PLC, and MAPK ( apresslp.gvpi.net )

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27 CHAPTER 3 MATERIALS AND METHODS HO1 Knockout Mouse Model C57BL/6 mice were used for this model since i t has previously been shown that this strain develops focused lesions that grow into large granulomas following M. avium infection; these granulomas exhibit central necrosis (caseous necrosis) similar to human granulomas described in tuberculosis lesions ( 7). We used the HO 1 knockout model developed by Kenneth D. Poss and Susumu Tonegawa as described ( 72). Briefly, the construct was designed to remove a 3.7kb XhoI HindIII fragment of murine DNA with intron sequence and coding sequence for the final 226 amino acids (Figure 3 1). Chimeric mice were generated as described (71 73) and HO 1 / (Hmox1 / ) were obtained by mating male chimeras with C57BL/6 females; these Hmox1+/animals were intercrossed to produce Hmox1/ mice. HO1 wild type (+/+) heter ozygous (+/ ) and knockout ( / ) mice were maintained in a breeding colony in a specific pathogen free (SPF) animal housing facility under Animal Care Services at the University of Florida. HO1 / male mice of 8 weeks of age were paired with heterozygous (+/ ) females of the same age and subsequent litters were genotyped for the HO 1 gene. Genotyping was done upon weaning mouse pups 21 days after birth. Mouse tissue was obtained by cutting a small piece (1cm) off the tip of the tail. This tissue was dig ested and genomic DNA was isolated using Extract N Amp Tissue PCR Kit (Sigma, St. Louis, MO). PCR was performed using specific primers for wild type and knockout (mutant) HO 1 genes. HO 1 Wild type primer sequence (forward, 5 GTA CAC TGA CTG TGG TRG GGG GAG 3, reverse, 5AGG GCC GAG TAG ATA TGG TAC3) and HO 1 mutant primer sequence (forward, 5GCT TGG GTG GAG AGG CTA TTC 3, reverse, 5 CAA GGT GAG ARG ACA GGA GAT C 3). The PCR product was run on a 2% agarose gel

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28 supplemented with Ethidium bromide for UV imaging of DNA. The molecular weight of the wild type and mutant gene products are 180base pairs and 290 base pairs respectively. M. Avium culture M. avium subspecies avium Chester (ATCC# 15769) was maintained in ATCC medium 90 Lowenstein Je nson medium and grown in LowensteinJensen Medium Slants (BD Biosciences, San Jose, CA) according to manufacturers instructions. Alternatively, colonies were grown on Middlebrook and Cohn 7H10 agar plates (BD Biosciences, San Jose, CA ) and incubated for 14 days at 37 degrees in 95% oxygen and 5% carbon dioxide. A stock solution was prepared and the concentration was measured by reading the optical density (OD) using a spectrophotometer at 600nm (BioRad Hercules, CA ). Bacteria were fr ozen in 1ml aliquots in 10% glycerol at 80 C at a concentration of 1.3 x 109Collection Of Serum Colony forming units (cfu)/ml. Frozen aliquots were thawed and briefly sonicated before each use. T he mice were euthanized in a desiccator with an overdose of Isoflourane, an analgesic (Webster veterinary supply, Sterling, MA). Then, whole blood was collected through the abdominal aorta using a 25 gauge needle. The blood was left at room temperature for 30 minutes to clot an d then centrifuged at 12,000 rpm to separate the serum from the red blood cells (RBCs). The serum was then aliq uoted and stored in a 80 C freezer for further analysis. Bronchial Alveolar Lavage Fluids (BALF) BALF was collected by ligating the trachea using thread and placing a catheter into the airway through the trachea. Fluids were collected by injecting 800 1000 of Hanks Balanced S alt S olution (HBSS) into the mouse lung via canulation of the trachea. The fluid was then re drawn and the process was repeated twice for a total volume of 1600was placed on ice and then centrifuged at 1500 g to pellet the cells and separate the supernatant.

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29 The supernatant was aliquoted a nd stored in a 80 C freezer until further use The BAL cell pellet was stored in Cel l Freezing Medium (Sigma, St. Louis, MO) and stored in a 80 C freezer Tissue Harvest We collected the lungs, liver, spleen and kidneys from each mouse following euthanasia. Some tissue was frozen in Optimal Cutting Temperature (OCT) compound (Sakura, Torrance, CA) and stored in 80 C. The rest was fixed in 4% Paraformaldehyde and stored in room temperature for 24 hours. This tissue was then transferred to 70% ethanol and stored at room temperature until used. Immuno histochemistry Lung tissue from sacrificed mice was fixed in 4% Paraformaldehyde for 24 hours then t ransferred to 70% Ethanol Tissue was sent for paraffin embedding and Hematoxylin and Eosin (H&E) staining to Histology Tech Services, Gainesville Florida. Paraffin embedded slides were s tained for CCR2 using Goat anti mouse primary antibody (Capralogics, Hardwick, MA) and ABC staining kit (Vector laboratories Burlingame, CA) according to manufacturer recommendations. Alternatively, slides were stained with primary antibody for HO 1 (Calb iochem, San Diego, CA). Briefly the slides were deparaffinzed using Xylenes (Fisher Scientific Fairlawn, NJ ). Slides were placed in Xylene solution for 5 minutes twice. The slides were then washed with 1X Phosphate Buffered Saline (PBS) for 2 minutes. Next, the slides were permeated by incubating with triton X 100 ( Sigma Aldrich, St. Louis, MO ) for 10 minutes and incubated with Hydrogen Peroxide for (H2O2) for 30 minutes. Normal goat serum (ABC kit) was then added for 30 minutes to block tissue from ba ckground or nonspecific binding. Primary antibody for CCR2 was added to slides for 1 hour followed by washing and addition of secondary antibody (ABC kit) for 30 minutes. The slides were them incubated for 5 minutes in

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30 DAB peroxidase substrate solution ( Vector laboratories Burlingame, CA) for color development. All slides were counter stained with Hematoxylin (fisher Scientific, Fair Lawn, NJ) for 30 seconds. Sections were visualized using a Nikon DIAPHOT inverted microscope. The ocular is magnified to 10 times (10x) and the objectives used were magnified to 10x, 20x or40x Pictures were taken using the SPOT Imaging Solutions software (Sterling Heights, MI). TIB 71 (RAW 264.7) C ells RAW 264 ( 7TIB 71) cells were obtained from American Type Culture Col lection ( Manassas, VA Co Culture of RAW 264.7 Cells With M Avium ). RAW 264 cells are macrophages derived from BALB/C mice and are known to produce lysozyme The base medium for this cell line is ATCC formulated Dulbeccos Modified Eagles Medium (DMEM) supplemented with 10% Fetal Bovine Serum (FBS), Fungizone ( MP Biomedicals United States Solon, OH) and Penicillin Streptomycin solution ( MP Biomedicals United States Solon, OH ). Cells were grown to confluence in 6well plates and the culture med ium was replaced with serum free medium (SFM) to perform the experiments. Camhi et al. have shown that HO 1 is induced in RAW 264.7 cells with treatment of LPS ( 74) TIB 71 c ell cultures were plated on 60mm culture plates (Corning, Lowell, MA ) at a concentration of 1x10^6 cells per plate and treated with M. avium in SFM at a concentration of 50x10^6 bacteria per plate or a ratio of 50:1 bacteria per cell. After reaching confluence, the plates were incubated at 37 C for different time points (4, 8, and 24 hours) and the cells and supernates were harvested. All treatments were done in triplicate. Cell culture supernates were stored in a 80 C freezer. Cell pellets were stored in either Buffer RLT (Qiagen, Valencia, CA) or RIPA cell lysis buffer (Sigma Aldrich, St. Louis, MO) for RNA isolation and Western Blot protein analysis respectively. The resulting samples were stored in a 80 C freezer until needed.

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31 HO1 Inhibition By Zinc Protoporphyrin IX In Cell Cultures Zinc protoporphyrinIX (ZnPP) is a normal metabolite that is formed in trace amounts during heme biosynthesis ( 75). ZnPP may regulate heme catabolism through competitive inhibition of HO 1 enzyme activity ZnPP is found in erythrocytes and is de posited in the spleen along with heme where both bind HO 1. This process slows down heme degradation by HO 1. ZnPP inhibits the enzyme activity of HO 1 but does not alter the gene and protein expression of HO1. Cells in culture were pretreated with ZnPP IX (Frontier Scientific, Logan, UT) for thirt y minutes in SFM The media is then cha nged to fresh SFM and the cells are exposed to different treatments as described above and incubated for different time points. Cells are collected, spun down and stor ed in RLT Lysis Buffer ( 10 parts RLT Lysis buffer, Qiagen sciences, MD, USA and 1 part 2Mercaptoethanol Bio Rad Laboratories Inc., Hercules, CA) for RN A isolation. Cell Supernates were also collected and stored in a 80 C freezer for cytokine studies. Mouse Model For M. Avium I nfection We have developed a murine model for M. avium infection and chronic colonization which leads to granuloma formation in the lungs and other tissue. C57BL /6 wild type and HO 1 knockout mice were inoculated intranasal with 7x106 M. avium in PBS once per week for three weeks. Alternatively, wild type control mice were inoculated with equal volume of PBS. Throat swabs were done once a month and plated on M. avium specific plates to monitor colonization. The swabs were plated on the aforementioned 7H10 plates (BD) and incubated for 14 days in a 37 C incubator with 95% O2 and 5% CO2. Colonies are visualized and counted on each plate to determine the level of colonization in each mouse. The mice were sacrificed at different t ime

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32 points (2, 4 and 6 months) and the lungs, spleen and liver were harvested. BALF, BAL cells and serum were collected. Cytokine Studies MCP 1 levels in cell culture supernatants, mouse sera and BALF were measured using Enzyme Linked ImmunoSorbent Assay (ELISA). We used a Quantikine Mouse CCL2/JE/MCP 1 immunoassay kit according to manufacturer recommendation (R&D systems Inc., Minneapolis, MN ). The cells and media are collected and centrifuged at 2000 RPM for 5 minutes. The culture supernates were collected and stored in a 80 C freezer until needed. 50 1 levels. The OD was measured at 450 nm in a Biotek Synergy 2 microplate reader using Gene5 software ( Biotek Industri es, Winooski, VT ). Real Time Polymerase Chain Reaction (RT PCR) Analysis Total RNA from cultured RAW 264 cells was purified and diluted with RNase free water to 100 ng/L; then, 10 L of each sample were reverse transcribed into combinational DNA (cDNA). Af ter the reverse transcription reaction was finished, 80 L of RNase free water were added to each sample. of diluted cDNA product were mixed with 25 L of SYBR Green JumpStart Taq ReadyMix, 0.5 L of internal reference dye, H2O and 2 L of specific oligonucleotide primers (80 nM final concentrations) to a total volume of 50 L for quantification of the real time polymerase chain reaction (PCR). The quantification of real time PCR was performed by using the SYBR Green method on the Appli ed Biosystems 7500 Real Time PCR System with the following profile: 1 cycle at 94C for 2 minutes; 40 cycles at 94C for 15 seconds, at 60C for 1 minute, and at 72C for 1 minute; and the at acquired fluorescent signal from the elongation step. Beta actin or 18s rRNA was used as a house keeping internal control. The real time PCR products were confirmed by electrophoresis on 2% agarose gels.

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33 cDNA was amplified using mRNA specific primers for mouse 18S rRNA (forward: 5 TGTCTCAAAGATTAAGCCATGCAT 3, revers e: 5 AACCATAACTGATTTAATGAGCCATTC 3), mouse MCP 1 (forward: 5 GGCTCAGCCAGATG CAGTTAA3, reverse:5 CCTACTCATTGGGATCATCTTGCT3) mouse CCR2 (forward: 5 CAACTCCTTCATCAGGCACAR 3 reverse: 5 GGAAAGAGGCAGTTTGCAAAG3) mouse HO 1 ( forward : 5 CTTTCAGAAGGGYC AGGTGWCC 3 reverse : 5 GTGGAGMCGCTTYACRTAGYGC 3 ) Data analysis was carried out by using the ABI sequencedetection software using relative quantification. The threshold cycle (Ct), which is defined as the cycle at which PCR amplification reaches a sig nificant value, is expressed as the mean value. The relative expression of messenger RNA (mRNA) was calculated by using the Ct method (where Ct is the value obtained by subtracting the Ct value of the housekeeping gene actin mRNA from the Ct value of the target mRNA). The amount of the target relative to actin or 18s rRNA mRNA was expressed as 2(Ct)Statistical Analysis The data o btained f r om independent experiments are pres ented as the mean +/ standard deviation; they were analyzed by the unpaired st udent t test using Statview software version 5.0, SAS Inst. INC. (Cary, NC). All experiments were done in triplicate. Differences were considered significant at P < 0.05 level

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34 Figure 3 1. Targeted disruption of the Hmox1 gene. (a) Hmox1 genomic locus and targeting vector A 3.7kb region including exons 3, 4 and a portion of 5 (e3 e5) was replaced with a pkgneo cassette. The 5 and 3 probes used for screening ES cell clones and genotyping mice are shown. The 5 probe hybridizes to an 11kb KpnI fragment of the native Hmox1 gene and a 6.5kb fragment from the disrupted gene. D, HindIII site; K, KpnI; X, XhoI; Xb, XbaI. (Poss, Tonegawa, 1997).

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35 CHAPTER 4 RESULTS In Vitro Results HO1 is induced by M. avium in RAW 264.7 cells We stained RAW 2 64.7 cells for HO 1 to test whether the expression levels of HO 1 are increased after insult with M. avium. Our results showed that HO 1 was induced by M. avium in RAW 264.7 cells after 4 hours (Figure 42) as opposed to controls (Figure 41). HO 1 was sti ll expressed at 8, 24 and 48 hours after exposure to M. avium as well (results not shown). We next looked at mRNA levels of HO 1 in RAW 264.7 cells in the presence and absence of M. avium in order to see whether M. avium induces gene expresison of HO 1. Our results showed that HO 1 expression was induced in a time dependent manner in this mouse monocyte cell line after M. avium treatment (Figure 4 3). MCP 1 relative gene expression in RAW 264.7 cells Following the same protocol as explained above, we analyzed the mRNA levels of MCP 1 in RA W 264.7 cells using real time PCR. After treatment with M. avium, MCP 1 mRNA levels increased in a time dependent manner as compared to controls, but these levels we re abrogated when we treated the cells with ZnPP a competitive inhibitor of HO 1 enzymatic activity, prior to M. avium exposure (Figure 44). CCR2 relative gene expression in RAW 264.7 cells In order to test whether M. avium infection and HO 1 inhibition affect gene expression of CCR2, mRNA levels of CCR2 were measured in TIB 71 (RAW 264.7) cells Our results indicate that when these cells are treated with ZnPP, CCR2 expression is significantly increased on the surface of mouse monocytes and this increa se is time dependent (Figure4 5)

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36 MCP 1 levels in Cell Culture Supernates To support our previous results obtained with RNA, we measured the levels of the same cytokine in RAW 264.7 cell culture supernates using ELISA. MCP 1 levels were significantly increased in a time dependent manner in cell culture supernates of cells that were treated with M. avium for 4, 8 and 24 hours, but the se levels were abrogated after treatment with ZnPP IX even with concurrent infection with M. avium (Figure 4 6). In Viv o Results Mouse t issue After euthanasia, we checked the lungs, liver and spleen of HO 1 +/+ and HO 1 / mice to ensure granuloma formation and therefore, infection has occurred. We observed that the lungs of HO1 +/+ and HO 1 / mice showed detectable d ifferences in granuloma formation. Figure 4 8 shows that HO 1 +/+ mice infected with M. avium formed granuloma in the lungs as compared to saline controls (figure 47). We then examined the lungs of HO 1 / mice to see whether they form similar lesions f ollowing infection with M. avium. Figure 410 shows that HO 1 / mice inoculated with M. avium do not form organized granulomas and have disseminated infection in the lung as compared to saline controls (figure 49) Immunohistochemistry To confirm the m ouse model of M. avium infection, we examined the formation of g ranuloma in lung tissue of infected mice. From analyzing our H&E stained tissue sections, it was evident in HO1+/+ mice developed granulomas after 6 months exposure to M. avium via intra nasal inoculation as compared to saline controls (Figure 411 ). These mice exhibited organized granuloma formation and were able to contain the pathogen to the site of infection. HO1 / mice displayed loose, unorganized lesions in the lungs after exposure t o M. avium as compared to their control counterparts (Figure 412 ).

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37 HO1 protein expression in mouse lung tissue We stained the lungs tissue of HO 1 +/+ control and infected mice to study whether M. avium infection induces HO 1 expression. HO1 level s were up regulated in granulomatous tissue in HO1 +/+ mouse lungs infected with M avium as compared to Control mice. Figure 4 13 shows a 100x magnification of a control lung from an HO 1 +/+ mouse which was inoculated with saline (PBS) which was stained for HO 1. This tissue exhibited basal levels of HO 1. Figures 4 14 and 415 show a 200x magnification of an HO 1 +/+ mouse lung stained for HO 1. This mouse was inoculated with M. avium for 6 months and shows upregulation of HO 1 in granulomatous tissue. CCR2 expression in mouse lung tissue To test and confirm previous results that showed that HO 1 regulates the expression of CCR2, we looked at CCR2 expression in the lung tissue of HO1 +/+ and HO 1 / infected and control mice Figure 4 16 shows that HO1 / mice have higher basal levels of CCR2 in lung tissue. CCR2 levels were up regulated in lung tissue of infected HO 1 +/+ mice as compared to uninfected controls (Figure 417). Additionally, we observed higher levels of CCR2 in infected lungs of HO 1 / mice as compared to infected HO 1 +/+ mice (Figure 418 ). In HO 1 +/+ mouse lung tissue, CCR2 colocalized to granulomas (figure 419). Our results showed that CCR2 is normally regulated by HO 1 in the lungs of HO 1 +/+ mice following infection. Figure 24 shows that CCR2 is colocalized to the granuloma and is not expressed in other areas of the lung. In HO 1 / mice we see that this regulation is lost and CCR2 is expressed in a much larger area of the lung and is disseminated after infection a s compared to CCR2 expression in HO 1 +/+ tissue from infected mice (Figure 420).

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38 MCP 1 l evels in BALF and serum When we analyzed the levels of MCP 1 in both BALF and serum, we observed a significant increase of MCP 1 in the BALF of infected wild type C5 7BL/6 mice as compared to uninfected controls and increased levels in infected HO 1 / mice as compared to knockout controls as measured with ELISA (Figure 421). Additionally, MCP 1 levels were higher in HO 1 / control mice as compared with wild type controls. MCP 1 levels were also increased in the sera of mice infected with M. avium as compared to control mice and the levels of MCP 1 in sera of HO 1 / mice infected with M. avium were significantly higher than wild type controls and HO1 / control s (Figure 422).

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39 Figure 4 1. 400x magnification stain of RAW 264.7 cells after 4 hours of incubation in SFM showing basal levels of HO 1. Blue color shows counter stain with Hematoxylin Figure 4 2. 400x stain of RAW 264.7 cells after 4 hours treatment with M. avium showing increased levels of HO 1 expression (brown). Blue color shows counter stain with Hematoxylin.

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40 Figure 4 3. HO 1 relative apparent gene expression significantly inc reases in a time dependent manner in mouse monocytes a fter treatment with M. avium. HO1 levels increase significantly (p < .001) in cells treated with M. avium ( *). RAW 264.7 cells were treated for 4, 8, 24 and 48 hours in serum free medium (C), or with M. avium. 0 1 2 3 4 5 6 7 8 Control M. aviumRelative Gene Expression 4 hour 8 hour 24 hour 48 hour*

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41 Figure 4 4. MCP 1 Relative Gene Expression significantly increased (p < .001) in monocytes after treatment with M. avium for 8 and 24 hours as compared to controls (*) and were significantly lowered when cells were pretreated with ZnPP for 8 and 24 hours (**) as compared to M. avium alone for the same time points RAW 264.7 cells were incubated for 4,8 and 24 hours in serum free media (Control) or treated with M. avium, or both ZnPP and M. avium 0 0.5 1 1.5 2 2.5 3 Control M. avium ZnPP + M. aviumReltive Gene ExpressionTreatments 4 hour 8 hour 24 hour* ** **

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42 Figure 4 5. CCR 2 Relative Gene Expression was significantly increased (p<.05 ) in M. avium treated monocytes as compared with controls at 4 hours (*), 8 hours (**), and 24 hours (***) and in cells treated with ZnPP and M. avium as compared to controls. RAW 264. 7 cells were incubated for 4, 8, and 24 hours in serum free media (Control), treated with M. avium or treated with both ZnPP and M. avium 0 1 2 3 4 5 6 7 Control M. avium ZnPP+M. aviumRelative Gene ExpressionSample 4 hour 8 hour 24 hour* ** *** ** ***

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43 Figure 4 6. MCP 1 levels significantly increase (p < .05) in cell supernates in a time dependent manner after treatment with M. avium as compared to controls (*) and are significantly decreased (p < .05) after inhibition of HO 1 with ZnPP as compared with M. avium treatment alone (**). 0 500 1000 1500 2000 2500 3000 3500 Control M. avium ZnPP + M. avium MCP-1 (pg/mL) 4 hour 8 hour 24 hour ** ** **

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44 Figure 4 7. HO1+/+ 6 month control lung. Control mice were inoculated with intranasal PBS Figure 4 8. HO 1 +/+ lung showing granuloma formation after 6 months exposure to M. avium via intranasal inoculation

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45 Figure 4 9. HO 1 / 6 month control lung. Control mice were inoculated with intranasal PBS. Figure 4 10. HO 1 / lungs showed disseminated infection and loose granuloma formation following 6 month exposure to M. avium.

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46 A B Figure 4 11. A) 100x magnification H&E stain of an HO 1 +/+ control mouse lung. B) 100x magnification H&E stain of an HO 1 +/+ mouse infected with M. avium for 6 months showing granuloma formation A B Figure 4 12. A) 100x magnification H&E stain of HO 1 / saline control lung. B) 100x magnification H&E stain of HO 1 / showing loose, unorganize d granulomas and disseminated infection in lung tissue following 6 month exposure to M. avium

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47 Figure 4 13. 100x magnification of control lung from HO 1 +/+ mouse showing basal levels of HO1 (brown). Figure 4 14. 200x magnification of M. avium infected HO 1 +/+ mouse lung tissue showing increased expression of HO 1 (brown) in granuloma. Blue color shows counter stain with Hematoxylin

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48 Figure 4 15. 200x magnification of granuloma in M. avium infected HO 1 +/+ mouse lung showing increased expression of HO 1 in granuloma. Blue color shows counter stain with Hematoxylin A B Figure 4 16. A) 100x magnification of control HO 1 +/+ control lung showing basal levels of CCR2 (brown) B) 100x magnification of HO 1 / control mouse lung showing basal levels of CCR2 (brown) Blue color shows counter stain with Hematoxylin

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49 A B Figure 4 17. A) 100x magnification of an HO 1+/+ control mouse lung tissue showing basal levels of CCR2 (brown). B) 100x magnification of an HO 1 +/+ mouse lung inoculated with M. avium for 6 months showing increased expression of CCR2 (brown). Blue color shows counter stain with Hematoxylin A B Figure 4 18. A) 100x magnification of an HO 1 +/+ mouse lung after 6 months M. avium infection showing CCR2 expression (brown). B) An increase in CCR2 expression in HO1 / mouse lung after 6 months of M. avium infection. Blue color shows counter stain with Hematoxylin

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50 A B Figure 4 19. A and B. 100x magnification of an HO 1 +/+ mouse lung after 6 month infection with M. avium showing CCR2 (brown) colocalizes with granuloma. Blue color shows counter stain with Hematoxylin A B Figure 4 20. A and B. 100x magnification of an HO 1 / mouse lung following 6 month infection with M. avium showing disseminated expression of CCR2 (brown). Blue color shows counter stain with Hematoxylin

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51 Figure 4 21. MCP 1 levels are significantly increased (p < .001) in BAL F of infected HO 1 +/+ and HO 1 / mice as compared with controls (*). Basal levels of MCP 1 are significantly higher (p < .001) in HO 1 / control mice as compared to HO 1 +/+ control mice (**). 0 200 400 600 800 1000 1200 1400 1600 HO 1 +/+ Control HO 1+/+ M. avium HO 1 / Control HO 1 / M. aviumMCP 1 pg/uL*

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52 Figure 4 22. MCP 1 levels are increased in mouse s erum after 6 month M. avium infection and are significantly higher (p < .0001) in infected HO 1 +/+ and HO 1 / mice ( *) as compared with saline controls. Significantly higher basal levels of MCP 1 are seen in HO1 / sera then HO 1 +/+ sera ( **). 0 50 100 150 200 250 300 350 400 450 Wild type Control Wild type M. avium HO 1 / Control HO 1 / M. avium MCP1 (pg/mL)Mouse Sample*

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53 CHAPTER 5 DISCUSSION Since the advent of HIV and the AIDS epidemic, NTM infections have become a major source of disease in the United States and around the world (1). Although NTM typically do not cause disease in humans, MAC infections have been on the rise in both immune c ompetent patients as well as the immunocompromised (2). The formation of granuloma is a vital part of the bodys immune defense against invading pathogens. After infection with M. avium, failure to develop organized granulomas results in the dissemination of the infection and greater injury to the host. The regulated recruitment of immune cells including monocyte macrophages, T cells, dendritic cells and B cells to the site of infection and injury is essential for the host to contain and eliminate invadin g pathogens (33). In this study, we tested the interaction and regulation of three proteins (HO 1, MCP 1 and CCR2) in the process of granuloma formation. HO 1, an inducible, cyto protective protein has been implicated in many inflammatory disease as well a s mycobacterial infections (45). We hypothesized that HO 1 plays a role in granuloma formation by regulating MCP 1 and CCR2 expression in mouse monocytes and therefore regulating the cellular recruitment of these immune cells from the periphery to the site of infection and injury. MCP 1 is a chemokine responsible for creating a gradient for the chemotaxis of immune cells from the periphery to the site of infection and CCR2 is the cell surface receptor which is bound by MCP 1 (25). MCP 1 and CCR2 are both highly involved in the process of cellular recruitment and in this study we demonstrate that HO 1 is a key regulator of these cytokines and therefore the immune recruitment process and granuloma formation. From our in vitro experiment using RAW 264.7 mous e monocytes, we observed that HO 1 is induced by M. avium as early as 4 hours post treatment and stays highly expressed for up to 48 hours (Figure 9). Once activated by M. avium, these monocytes began to express higher levels of both MCP 1 (Figure

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54 10) and CCR2 (Figure11). However, when we treated the cells with ZnPP, a competitive inhibitor for HO 1 enzyme activity, we saw a decreased expression of MCP 1 and an increase expression of CCR2, suggesting that HO 1 levels are directly correlated with MCP 1 ex pression and inversely cor related with CCR2 expression. Previous findings have given contradicting evidence in terms of the correlation between HO 1, MCP 1 and CCR2. In many studies, the level of both MCP 1 mRNA and protein were reduced with the inhibiti on of HO 1 (34), but in others, the opposite finding was observed (57). Zampetaki et al (45) have shown that despite high mRNA levels, significantly lower levels of cytokine protein were found in BALF of mice over expressing HO 1. These findings suggest that HO 1 over expression can suppress the signaling pathway. Our in vitro and in vivo results, however, show that inhibiting HO 1 enzyme activity led to a decrease in M CP 1 protein levels in cell supernates (Figure 12), BALF (Figure 27) and mouse serum (Figure 28), suggesting that HO 1 is directly correlated to MCP 1 expression in mouse monocytes. Since we observed an induction of HO 1 and increased levels of MCP 1 in t he lung tissue, BALF and serum of infected HO 1 +/+ mice, it is possible that an MCP 1 gradient was established in order to recruit monocytes from the peripheral blood to the site of infection. This corresponds to a normal immune response in which cells e xpressing CCR2 are recruited from the periphery and chemotax along an MCP 1 gradient towards the site of insult in order to from granulomas (28). When testing MCP 1 protein levels in infected mice, we observed higher basal levels of MCP 1 in sera and BALF in control HO 1 / mice as compared to wild type controls. These results support previous findings (46) and suggest that HO1 / mice are in a chronic state of inflammation. This chronic inflammatory state could lead

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55 to the destruction of the MCP 1 chem otactic gradient which would then disrupt cellular recruitment to the site of infection. Previous findings along with our results suggest that different cell types in different organ systems may react differently to altered levels of HO 1. This could be the result of direct regulation by HO 1 on MCP CCR2 receptor on monocytes and macrophages in the vicinity of the infection which creates a negative feedback loop between CCR2 and MCP 1. It has been reported that when HO 1 enzymatic activity is inhibited by ZnPP, the levels of CCR2 increase (48, 49) suggesting that HO1 somehow regulates the expression of CCR2 on the surface of monocytes, macrophages and other immune cells. Our results show that HO 1 / mice indeed had increased levels of CCR2 on monocyte/macrophage cell surfaces as seen by relative gene expression (Figure 11) and immunohistochemistry (Figure 26). Our findings also suggest that HO 1 normally regulates the expression of the CCR2 during infection and allows these cells to chemotax along an MCP 1 gradient towards infection. When we analyzed the results from our in vivo mouse model, we observed that the loss of HO 1 expression led to loose or unorganized granuloma formation in mice following M. avium infection. The inability of these mice to form solid granulomas led to a disseminated infection with more inflammation and more lesions covering a greater area of the lungs, liver and spleen. As Figure 18 shows, HO 1 / mice had loose, unorganized granulomas in the lungs. It is possible that these mice did not contain the mycobacterium as compared to HO 1 +/+ mice and therefore had disseminated infections. These findings suggest that HO 1 plays a critical role in the regulation o f cellular recruitment to the site of infection and in organized granuloma formation. When analyzing our HO 1 / mouse tissue and immunohistochemistry, we observed that the lack of the HO 1 gene in mice infected with M. avium led to sever e

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56 disseminated i nfection, loose, unorganized granulomas and greater pathology as compared with their HO 1 +/+ counterparts which formed organized granulomas after infection. This is a significant finding because we can now focus our efforts on the direct role of HO 1 in t he process of granuloma formation and cellular recruitment to the site of infection in the live animal. Our HO 1 / mouse model has given us a useful tool in the study of granuloma formation following M. avium infection. Our studies have helped shed lig ht on the role of HO 1 in the regulation of MCP 1 and CCR2 and in the process of cellular recruitment during and following mycobacterial infection.

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57 CHAPTER 6 FUTURE CONSIDERATIONS Having established an HO 1 / animal model of M. avium infection and gr anuloma formation, we can now focus on the direct role of HO 1 in the innate and adaptive immune responses, specifically focusing on granuloma formation. We plan to further elucidate the role of HO1 in regulating cytokines such as MCP 1 and CCR2 and how this regulation affects cellular recruitment from the periphery to sites of infection and inflammation. As stated previously, HO 1 expression may exert different physiological changes in different organ systems and cell types. We can now study the effect s of HO 1 or lack thereof, in several organs, cell types and in different states of health. We can also concentrate on the different aspects of heme catabolism by HO 1 which may affect this immune process. We plan on testing the affects of free iron (Fe+ ), Billirubin, and CO2 on granuloma formation and the immune response to M. avium infection. Another challenge will be to test whether it is possible to rescue the cyto protective role of HO 1 in HO 1 / mice by treating them with one or more of the catabolic byproducts of heme degradation. Another possibility is the use of HO 1 therapy to treat NTM infected patients with HIV or AIDS in the hopes of rescuing their immune function. With these future studies, we hope to contribute not only to the scientif ic field of microbiology, but also to the clinical and therapeutic areas of medicine. Hopefully our findings will help us understand the mechanisms of NTM infection and help prevent such diseases in the future. Alternatively, we hope that our study will he lp elucidate the role of HO 1 in NTM disease and will lead to a better understanding of how to approach and treat other disease caused by both NTM and Mycobacterium tuberculosis.

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65 BIOGRAPHICAL SKETCH Doron Regev was born in Tel Hashomer, Israel. He grew up in Kfar Saba, Israel and moved to the United States at the age of 8. Doron spent most of his childhood in Rochester, NY and graduated from Brighton High School in 1995. He earned his bachelors degree in Biology from the University at Albany (NY) in 1999. Doron also excelled as a collegiate football player at Albany, earn ing a first team AllAmerican award as a place kicker his senior year. Following college, Doron pursued a career as a football player and in 2001, played for the Rochester Brigade, a professional arena football team in Rochester, NY. He later decided to embark on a scientific career and began his research at the University of Rochester, where he worked in a cardiovascular research lab for two years. He then moved to Gainesville Florida where he worked in a pulmonary research lab under Dr. Veena Antony an d entered the MS program at the University of F lorida. Upon completion of his m aster s degree, Doron will continue his studies in the IPD program at the University of Florida in the hopes of attaining a Ph.D. in medical sciences.