1
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Chaurasiya SK. Tuberculosis: Smart manipulation of a lethal host. Microbiol Immunol 2018; 62:361-379. [PMID: 29687912 DOI: 10.1111/1348-0421.12593] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/21/2018] [Accepted: 04/16/2018] [Indexed: 11/28/2022]
Abstract
Tuberculosis (TB) caused by Mycobacterium tuberculosis remains a global threat to human health. Development of drug resistance and co-infection with HIV has increased the morbidity and mortality caused by TB. Macrophages serve as primary defense against microbial infections, including TB. Upon recognition and uptake of mycobacteria, macrophages initiate a series of events designed to lead to generation of effective immune responses and clearance of infection. However, pathogenic mycobacteria utilize multiple mechanisms for manipulating macrophage responses to protect itself from being killed and to survive within these cells that are designed to kill them. The outcomes of mycobacterial infection are determined by several host- and pathogen-related factors. Significant advancements in understanding mycobacterial pathogenesis have been made in recent years. In this review, some of the important factors/mechanisms regulating mycobacterial survival inside macrophages are discussed.
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Affiliation(s)
- Shivendra K Chaurasiya
- Host-pathogen Interaction and Signal Transduction Laboratory, Department of Microbiology, School of Biological Sciences, Dr. Hari Singh Gour University, Sagar, MP-470003, India
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2
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Thirunavukkarasu S, Plain KM, Purdie AC, Whittington RJ, de Silva K. IFN-γ fails to overcome inhibition of selected macrophage activation events in response to pathogenic mycobacteria. PLoS One 2017; 12:e0176400. [PMID: 28505170 PMCID: PMC5432162 DOI: 10.1371/journal.pone.0176400] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 04/10/2017] [Indexed: 01/25/2023] Open
Abstract
According to most models of mycobacterial infection, inhibition of the pro-inflammatory macrophage immune responses contributes to the persistence of bacteria. Mycobacterium avium subsp. paratuberculosis (MAP) is a highly successful pathogen in cattle and sheep and is also implicated as the causative agent of Crohn's disease in humans. Pathogenic mycobacteria such as MAP have developed multiple strategies to evade host defence mechanisms including interfering with the macrophages' capacity to respond to IFN-γ, a feature which might be lacking in non-pathogenic mycobacteria such as M. smegmatis. We hypothesized that pre-sensitisation of macrophages with the pro-inflammatory cytokine IFN-γ would help in overcoming the inhibitory effect of MAP or its antigens on macrophage inflammatory responses. Herein we have compared a series of macrophage activation parameters in response to MAP and M. smegmatis as well as mycobacterial antigens. While IFN-γ did overcome the inhibition in immune suppressive mechanisms in response to MAP antigen as well as M. smegmatis, we could not find a clear role for IFN-γ in overcoming the inhibition of macrophage inflammatory responses to the pathogenic mycobacterium, MAP. We demonstrate that suppression of macrophage defence mechanisms by pathogenic mycobacteria is unlikely to be overcome by prior sensitization with IFN-γ alone. This indicates that IFN-γ signaling pathway-independent mechanisms may exist for overcoming inhibition of macrophage effector functions in response to pathogenic mycobacteria. These findings have important implications in understanding the survival mechanisms of pathogenic mycobacteria directed towards finding better therapeutics and vaccination strategies.
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Affiliation(s)
- Shyamala Thirunavukkarasu
- The University of Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Sydney, Australia
| | - Karren M. Plain
- The University of Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Sydney, Australia
| | - Auriol C. Purdie
- The University of Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Sydney, Australia
| | - Richard J. Whittington
- The University of Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Sydney, Australia
| | - Kumudika de Silva
- The University of Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Sydney, Australia
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3
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Masumi A, Mochida K, Takizawa K, Mizukami T, Kuramitsu M, Tsuruhara M, Mori S, Shibayama K, Yamaguchi K, Hamaguchi I. Mycobacterium avium infection induces the resistance of the interferon-γ response in mouse spleen cells at late stages of infection. Inflamm Regen 2016; 36:21. [PMID: 29259694 PMCID: PMC5725973 DOI: 10.1186/s41232-016-0024-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/02/2016] [Indexed: 11/14/2022] Open
Abstract
Background Bacterial infections cause an increase in the population of hematopoietic stem cells (HSCs). To investigate the downstream factors associated with hematopoietic stem cells, mice are infected with Mycobacterium avium (M. avium). Results Mycobacterium avium (M. avium) infection induces the enlargement of the spleen and changes in histopathology, including changes to the lineage populations. A dramatic expansion of Lin−c-kit+Sca-1+ (KSL) cells in mouse bone marrow cells and spleen cells was detected 4 weeks after infection with M. avium; however, there was no difference in the engraft activity between infected and un-infected mouse bone marrow cells. We tested the cytokine and cytokine-related gene expression after M. avium infection and found that IFN-γ expression increased and peaked at 4 weeks in both bone marrow and spleen cells. The expression of Sca-1 gene peaked at 4 weeks in the bone marrow but peaked at 2 weeks in spleen cells, although the Sca-1 surface marker peaked at 4 weeks after infection in both bone marrow and spleen cells. Interferon regulatory factor-2 (IRF-2) expression did not change in the bone marrow cells, whereas it decreased in spleen cells at 4 weeks and IRF-1 expression was up-regulated in both bone marrow and spleen cells after infection. However, the up-regulation of IRF-1 was not correlated with IFN-γ expression in the M. avium-infected mouse spleen cells. Conclusions This finding suggests that the IFN-γ production mediated by M. avium infection alters the population of KSL cells during host defense, and the down-regulation of the IFN-γ response in spleen cells occurs at the late stage after M. avium infection.
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Affiliation(s)
- Atsuko Masumi
- Department of Safety Research on Blood and Biological Products, National Institute of Infectious Diseases, Tokyo, Japan.,Present address: Faculty of Pharmaceutical Sciences, Aomori University, 2-3-1, Kohbata, Aomori-shi, Aomori, 030-0943 Japan
| | - Keiko Mochida
- Department of Bacteriology II, National Institute of Infectious Diseases, 4-7-1, Gakuen Musashimurayama-shi, Tokyo, 208-0011 Japan
| | - Kazuya Takizawa
- Department of Safety Research on Blood and Biological Products, National Institute of Infectious Diseases, Tokyo, Japan
| | - Takuo Mizukami
- Department of Safety Research on Blood and Biological Products, National Institute of Infectious Diseases, Tokyo, Japan
| | - Madoka Kuramitsu
- Department of Safety Research on Blood and Biological Products, National Institute of Infectious Diseases, Tokyo, Japan
| | - Momoka Tsuruhara
- Department of Safety Research on Blood and Biological Products, National Institute of Infectious Diseases, Tokyo, Japan
| | - Shigetarou Mori
- Department of Bacteriology II, National Institute of Infectious Diseases, 4-7-1, Gakuen Musashimurayama-shi, Tokyo, 208-0011 Japan
| | - Keigo Shibayama
- Department of Bacteriology II, National Institute of Infectious Diseases, 4-7-1, Gakuen Musashimurayama-shi, Tokyo, 208-0011 Japan
| | - Kazunari Yamaguchi
- Department of Safety Research on Blood and Biological Products, National Institute of Infectious Diseases, Tokyo, Japan
| | - Isao Hamaguchi
- Department of Safety Research on Blood and Biological Products, National Institute of Infectious Diseases, Tokyo, Japan
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4
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Nalpas NC, Magee DA, Conlon KM, Browne JA, Healy C, McLoughlin KE, Rue-Albrecht K, McGettigan PA, Killick KE, Gormley E, Gordon SV, MacHugh DE. RNA sequencing provides exquisite insight into the manipulation of the alveolar macrophage by tubercle bacilli. Sci Rep 2015; 5:13629. [PMID: 26346536 PMCID: PMC4642568 DOI: 10.1038/srep13629] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 07/31/2015] [Indexed: 12/24/2022] Open
Abstract
Mycobacterium bovis, the agent of bovine tuberculosis, causes an estimated $3 billion annual losses to global agriculture due, in part, to the limitations of current diagnostics. Development of next-generation diagnostics requires a greater understanding of the interaction between the pathogen and the bovine host. Therefore, to explore the early response of the alveolar macrophage to infection, we report the first application of RNA-sequencing to define, in exquisite detail, the transcriptomes of M. bovis-infected and non-infected alveolar macrophages from ten calves at 2, 6, 24 and 48 hours post-infection. Differentially expressed sense genes were detected at these time points that revealed enrichment of innate immune signalling functions, and transcriptional suppression of host defence mechanisms (e.g., lysosome maturation). We also detected differentially expressed natural antisense transcripts, which may play a role in subverting innate immune mechanisms following infection. Furthermore, we report differential expression of novel bovine genes, some of which have immune-related functions based on orthology with human proteins. This is the first in-depth transcriptomics investigation of the alveolar macrophage response to the early stages of M. bovis infection and reveals complex patterns of gene expression and regulation that underlie the immunomodulatory mechanisms used by M. bovis to evade host defence mechanisms.
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Affiliation(s)
- Nicolas C Nalpas
- Animal Genomics Laboratory, UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - David A Magee
- Animal Genomics Laboratory, UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Kevin M Conlon
- UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - John A Browne
- Animal Genomics Laboratory, UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Claire Healy
- UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Kirsten E McLoughlin
- Animal Genomics Laboratory, UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Kévin Rue-Albrecht
- Animal Genomics Laboratory, UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.,UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Paul A McGettigan
- Animal Genomics Laboratory, UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Kate E Killick
- Systems Biology Ireland, UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin 4, Ireland
| | - Eamonn Gormley
- Tuberculosis Diagnostics and Immunology Research Centre, UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Stephen V Gordon
- UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.,UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin 4, Ireland.,UCD School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland.,UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin 4, Ireland
| | - David E MacHugh
- Animal Genomics Laboratory, UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.,UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin 4, Ireland
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5
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Thirunavukkarasu S, de Silva K, Whittington RJ, Plain KM. In vivo and in vitro expression pattern of Toll-like receptors in Mycobacterium avium subspecies paratuberculosis infection. Vet Immunol Immunopathol 2013; 156:20-31. [PMID: 24054090 DOI: 10.1016/j.vetimm.2013.08.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 08/16/2013] [Accepted: 08/20/2013] [Indexed: 10/26/2022]
Abstract
Johne's disease (JD) caused by Mycobacterium avium subspecies paratuberculosis (MAP) is a chronic infectious disease of ruminants. Activation of the Toll-like receptors (TLR) in response to microbial stimuli, including MAP, initiates responses in immune cells of the blood and within peripheral tissues. TLR2, 4 and 9 are believed to play a critical role in the initiation of immune responses against mycobacteria. In this study we report on the in vivo expression pattern of these receptors in sheep and cattle experimentally exposed to MAP. Experiments using the mouse macrophage cell line, RAW 264.7, and on isolated bovine monocytes were also carried out to assess the expression pattern of TLR2 and 4 in response to MAP and the non-pathogenic mycobacterial strain, M. smegmatis. Results from the in vivo study showed that there was a significant upregulation of TLR2 (P<0.05) at early time-points post-inoculation in the peripheral blood cells of sheep exposed to MAP S strain that went on to develop severe (multibacillary) disease. However, in the cattle during the initial months post-exposure to MAP C strain, TLR2 was significantly downregulated (P<0.05). TLR4 was significantly upregulated (P<0.05) at later stages (12 months post-inoculation) in MAP-exposed sheep with multibacillary disease; however significant differences in TLR4 expression were not observed in cattle. Expression of TLR9 was unchanged in MAP-exposed sheep and cattle. In vitro studies on mouse macrophages supported the findings of in vivo TLR2 gene expression increases seen in the sheep, in that the TLR2 receptor expression in response to MAP-infection was significantly increased in comparison to cells infected with a non-virulent mycobacterium, M. smegmatis. A likely role for TLR2 in the pathogenesis of Johne's disease is proposed.
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Affiliation(s)
- Shyamala Thirunavukkarasu
- Faculty of Veterinary Science, The University of Sydney, 425 Werombi Road, Camden, NSW 2570, Australia
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6
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Yang D, Liu B, Hou X, Jiao D, Li X, Wen L, Zhu P, Fu N. Pre-treatment with Mycobacterium avium-derived lipids reduces the macrophage response to interferon γ in BCG-vaccinated mice. J Med Microbiol 2013; 62:980-987. [PMID: 23579397 DOI: 10.1099/jmm.0.056283-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mycobacterium bovis Bacille Calmette-Guérin (BCG) is the current vaccine used against Mycobacterium tuberculosis (MTB) infection. However, exposure to environmental pathogens, such as Mycobacterium avium, interferes with the immune response induced by BCG vaccination. How M. avium affects the efficiency of BCG is unclear. In this study, BCG-vaccinated mice pre-treated with M. avium-derived lipids (MALs) showed a higher mycobacterial load and increased infiltration of inflammatory cells compared to control mice treated with Escherichia coli-derived lipids (ELs). Unexpectedly, there were no changes in cell proliferation or IFN-γ levels in spleen cells stimulated with protein purified derivatives (PPD) or heat-inactivated BCG in MALs-treated mice. However, pre-treatment with MALs decreased the bactericidal effect as well as the production of TNF-α and nitric oxide (NO) in murine macrophages from BCG-vaccinated mice stimulated with IFN-γ. These results suggest that MAL pre-treatment dampens the immune response against MTB and that this dampening is associated with a decreased response to IFN-γ stimulation in murine macrophages. T-lymphocyte responses, however, were unaffected.
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Affiliation(s)
- Daqing Yang
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| | - Beiyi Liu
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| | - Xiaoriu Hou
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| | - Delong Jiao
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| | - Xueli Li
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| | - Liyan Wen
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| | - Ping Zhu
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| | - Ning Fu
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
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7
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Hart BE, Tapping RI. Differential trafficking of TLR1 I602S underlies host protection against pathogenic mycobacteria. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2012; 189:5347-55. [PMID: 23105135 PMCID: PMC3504178 DOI: 10.4049/jimmunol.1201545] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We recently identified I602S as a frequent single-nucleotide polymorphism of human TLR1 that greatly inhibits cell surface trafficking, confers hyporesponsiveness to TLR1 agonists, and protects against the mycobacterial diseases leprosy and tuberculosis. Because mycobacteria are known to manipulate the TLR system to their advantage, we hypothesize that the hyporesponsive 602S variant may confer protection by enabling the host to overcome this immune subversion. We report that primary human monocytes and macrophages from homozygous TLR1 602S individuals are resistant to mycobacterial-induced downregulation of macrophage MHC class II, CD64, and IFN-γ responses compared with individuals who harbor the TLR1 602I variant. Additionally, when challenged with mycobacterial agonists, macrophages from TLR1 602S/S individuals resist induction of host arginase-1, an enzyme that depletes cellular arginine stores required for the production of antimicrobial reactive nitrogen intermediates. The differences in cell activation mediated by TLR1 602S and TLR1 602I are observed upon stimulation with soluble mycobacterial-derived agonists but not with whole mycobacterial cells. Taken together, these results suggest that the TLR1 602S variant protects against mycobacterial disease by preventing soluble mycobacterial products, perhaps released from granulomas, from disarming myeloid cells prior to their encounter with whole mycobacteria.
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Affiliation(s)
- Bryan E. Hart
- Department of Microbiology, University of Illinois, Urbana, IL 61801
| | - Richard I. Tapping
- Department of Microbiology, University of Illinois, Urbana, IL 61801
- College of Medicine, University of Illinois, Urbana, IL 61801
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8
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Genetic Diversity of Toll-Like Receptors and Immunity to M. leprae Infection. J Trop Med 2012; 2012:415057. [PMID: 22529866 PMCID: PMC3317006 DOI: 10.1155/2012/415057] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 12/02/2011] [Indexed: 12/31/2022] Open
Abstract
Genetic association studies of leprosy cohorts across the world have identified numerous polymorphisms which alter susceptibility and outcome to infection with Mycobacterium leprae. As expected, many of the polymorphisms reside within genes that encode components of the innate and adaptive immune system. Despite the preponderance of these studies, our understanding of the mechanisms that underlie these genetic associations remains sparse. Toll-like receptors (TLRs) have emerged as an essential family of innate immune pattern recognition receptors which play a pivotal role in host defense against microbes, including pathogenic strains of mycobacteria. This paper will highlight studies which have uncovered the association of specific TLR gene polymorphisms with leprosy or tuberculosis: two important diseases resulting from mycobacterial infection. This analysis will focus on the potential influence these polymorphic variants have on TLR expression and function and how altered TLR recognition or signaling may contribute to successful antimycobacterial immunity.
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9
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An Assay in Microtitre Plates for Absolute Abundance of Chicken Interferon Alpha Transcripts. ACTA VET BRNO 2010. [DOI: 10.2754/avb201079030431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Immunosuppression of commercial chickens is a serious animal health and economic problem in the poultry industry. The major causes of the immunosuppression are viruses that suppress transcription of interferon genes, especially interferon alpha. There is a need for monitoring immunosuppression in commercially bred chickens. For this purpose, the absolute abundance of interferon alpha transcripts can be measured in blood of chickens by a suitable assay. Such an assay was used to estimate abundance of chicken interferon alpha in a sample of splenic cells induced with polyinosinic polycytidylic acid. The abundance measured was 29 ± 2 attomoles/µg total RNA. This assay can be performed in microtitre plates using samples collected from chickens in poultry houses.
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10
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Regulation of antigen presentation by Mycobacterium tuberculosis: a role for Toll-like receptors. Nat Rev Microbiol 2010; 8:296-307. [PMID: 20234378 DOI: 10.1038/nrmicro2321] [Citation(s) in RCA: 282] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mycobacterium tuberculosis survives in antigen-presenting cells (APCs) such as macrophages and dendritic cells. APCs present antigens in association with major histocompatibility complex (MHC) class II molecules to stimulate CD4(+) T cells, and this process is essential to contain M. tuberculosis infection. Immune evasion allows M. tuberculosis to establish persistent or latent infection in macrophages and results in Toll-like receptor 2 (TLR2)-dependent inhibition of MHC class II transactivator expression, MHC class II molecule expression and antigen presentation. This reduction of antigen presentation might reflect a general mechanism of negative-feedback regulation that prevents excessive T cell-mediated inflammation and that M. tuberculosis has subverted to create a niche for survival in infected macrophages and evasion of recognition by CD4(+) T cells.
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11
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Sow FB, Alvarez GR, Gross RP, Satoskar AR, Schlesinger LS, Zwilling BS, Lafuse WP. Role of STAT1, NF-kappaB, and C/EBPbeta in the macrophage transcriptional regulation of hepcidin by mycobacterial infection and IFN-gamma. J Leukoc Biol 2009; 86:1247-58. [PMID: 19652026 DOI: 10.1189/jlb.1208719] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Hepcidin is an antimicrobial peptide involved in regulating iron homeostasis. It is induced by iron overload and decreased by hypoxia and anemia. Hepcidin regulates iron metabolism by inhibiting iron absorption by the duodenum and by inhibiting macrophage iron recycling. Hepcidin is induced in hepatocytes during the acute-phase response by IL-6. Previously, we have shown that hepcidin is not induced in macrophages by IL-6 but is induced by the synergistic interaction of IFN-gamma and Mycobacterium tuberculosis infection. In the present study, we examined the pathways involved in inducing macrophage hepcidin expression. We show that TLRs TLR2 and TLR4 and the transcription factor STAT1 are required for induction of hepcidin mRNA. Hepcidin promoter activity is also synergistically induced in RAW264.7 macrophages by IFN-gamma and M. tuberculosis. NF-kappaB and C/CEBP binding sites are required for promoter activity. Binding of NF-kappaB (p50/p65) to the NF-kappaB site and STAT1 and C/EBPbeta to the C/CEBP site was confirmed by EMSA. Knockdown of STAT1 and C/EBPbeta expression in RAW264.7 cells with siRNA plasmids inhibited hepcidin promoter activity induced by IFN-gamma and M. tuberculosis. Together, these studies demonstrate that macrophage hepcidin expression is induced by the activation of STAT1 and NF-kappaB and the induction of C/EBPbeta expression.
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Affiliation(s)
- Fatoumata B Sow
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
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12
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Benson SA, Ernst JD. TLR2-dependent inhibition of macrophage responses to IFN-gamma is mediated by distinct, gene-specific mechanisms. PLoS One 2009; 4:e6329. [PMID: 19629181 PMCID: PMC2710511 DOI: 10.1371/journal.pone.0006329] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Accepted: 06/22/2009] [Indexed: 11/22/2022] Open
Abstract
Mycobacterium tuberculosis uses multiple mechanisms to avoid elimination by the immune system. We have previously shown that M. tuberculosis can inhibit selected macrophage responses to IFN-γ through TLR2-dependent and -independent mechanisms. To specifically address the role of TLR2 signaling in mediating this inhibition, we stimulated macrophages with the specific TLR2/1 ligand Pam3CSK4 and assayed responses to IFN-γ. Pam3CSK4 stimulation prior to IFN-γ inhibited transcription of the unrelated IFN-γ-inducible genes, CIITA and CXCL11. Surface expression of MHC class II and secretion of CXCL11 were greatly reduced as well, indicating that the reduction in transcripts had downstream effects. Inhibition of both genes required new protein synthesis. Using chromatin immunoprecipitation, we found that TLR2 stimulation inhibited IFN-γ-induced RNA polymerase II binding to the CIITA and CXCL11 promoters. Furthermore, TATA binding protein was unable to bind the TATA box of the CXCL11 promoter, suggesting that assembly of transcriptional machinery was disrupted. However, TLR2 stimulation affected chromatin modifications differently at each of the inhibited promoters. Histone H3 and H4 acetylation was reduced at the CIITA promoter but unaffected at the CXCL11 promoter. In addition, NF-κB signaling was required for inhibition of CXCL11 transcription, but not for inhibition of CIITA. Taken together, these results indicate that TLR2-dependent inhibition of IFN-γ-induced gene expression is mediated by distinct, gene-specific mechanisms that disrupt binding of the transcriptional machinery to the promoters.
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Affiliation(s)
- Sarah A. Benson
- Department of Medicine, Division of Infectious Diseases, New York University School of Medicine, New York, New York, United States of America
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - Joel D. Ernst
- Department of Medicine, Division of Infectious Diseases, New York University School of Medicine, New York, New York, United States of America
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
- Department of Pathology, New York University School of Medicine, New York, New York, United States of America
- * E-mail:
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13
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Yang X, Nesbitt NM, Dubnau E, Smith I, Sampson NS. Cholesterol metabolism increases the metabolic pool of propionate in Mycobacterium tuberculosis. Biochemistry 2009; 48:3819-21. [PMID: 19364125 DOI: 10.1021/bi9005418] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mycobacterium tuberculosis can metabolize cholesterol to both acetate and propionate. The mass of isolated phthiocerol dimycoserate, a methyl-branched fatty acylated polyketide, was used as a reporter for intracellular propionate metabolic flux. When M. tuberculosis is grown using cholesterol as the only source of carbon, a 42 amu increase in average phthiocerol dimycoserate molecular weight is observed, consistent with the cellular pool of propionate and, thus, methylmalonyl CoA increasing upon cholesterol metabolism. In contrast, no shift in phthiocerol dimycoserate molecular weight is observed upon supplementation of medium containing glycerol and glucose with cholesterol. We conclude that cholesterol is a significant source of propionate only in the absence of sugar carbon sources.
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Affiliation(s)
- Xinxin Yang
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, USA
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14
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Parsa KVL, Butchar JP, Rajaram MVS, Cremer TJ, Gunn JS, Schlesinger LS, Tridandapani S. Francisella gains a survival advantage within mononuclear phagocytes by suppressing the host IFNgamma response. Mol Immunol 2008; 45:3428-37. [PMID: 18514317 DOI: 10.1016/j.molimm.2008.04.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Revised: 03/31/2008] [Accepted: 04/02/2008] [Indexed: 10/22/2022]
Abstract
Tularemia is a zoonotic disease caused by the Gram-negative intracellular pathogen Francisella tularensis. These bacteria evade phagolysosomal fusion, escape from the phagosome and replicate in the host cell cytoplasm. IFNgamma has been shown to suppress the intra-macrophage growth of Francisella through both nitric oxide-dependent and -independent pathways. Since Francisella is known to subvert host immune responses, we hypothesized that this pathogen could interfere with IFNgamma signaling. Here, we report that infection with Francisella suppresses IFNgamma-induced STAT1 expression and phosphorylation in both human and murine mononuclear phagocytes. This suppressive effect of Francisella is independent of phagosomal escape or replication and is mediated by a heat-stable and constitutively expressed bacterial factor. An analysis of the molecular mechanism of STAT1 inhibition indicated that expression of SOCS3, an established negative regulator of IFNgamma signaling, is highly up-regulated during infection and suppresses STAT1 phosphorylation. Functional analyses revealed that this interference with IFNgamma signaling is accompanied by the suppression of IP-10 production and iNOS induction resulting in increased intracellular bacterial survival. Importantly, the suppressive effect on IFNgamma-mediated host cell protection is most effective when IFNgamma is added post infection, suggesting that the bacteria establish a permissive environment within the host cell.
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Affiliation(s)
- Kishore V L Parsa
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA
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Kincaid EZ, Wolf AJ, Desvignes L, Mahapatra S, Crick DC, Brennan PJ, Pavelka MS, Ernst JD. Codominance of TLR2-dependent and TLR2-independent modulation of MHC class II in Mycobacterium tuberculosis infection in vivo. THE JOURNAL OF IMMUNOLOGY 2007; 179:3187-95. [PMID: 17709534 DOI: 10.4049/jimmunol.179.5.3187] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mycobacterium tuberculosis is an exceptionally successful human pathogen. A major component of this success is the ability of the bacteria to infect immunocompetent individuals and to evade eradication by an adaptive immune response that includes production of the macrophage-activating cytokine, IFN-gamma. Although IFN-gamma is essential for arrest of progressive tuberculosis, it is insufficient for efficacious macrophage killing of the bacteria, which may be due to the ability of M. tuberculosis to inhibit selected macrophage responses to IFN-gamma. In vitro studies have determined that mycobacterial lipoproteins and other components of the M. tuberculosis cell envelope, acting as agonists for TLR2, inhibit IFN-gamma induction of MHC class II. In addition, M. tuberculosis peptidoglycan and IL-6 secreted by infected macrophages inhibit IFN-gamma induction of MHC class II in a TLR2-independent manner. To determine whether TLR2-dependent inhibition of macrophage responses to IFN-gamma is quantitatively dominant over the TLR2-independent mechanisms in vivo, we prepared mixed bone marrow chimeric mice in which the hemopoietic compartment was reconstituted with a mixture of TLR(+/+) and TLR2(-/-) cells. When the chimeric mice were infected with M. tuberculosis, the expression of MHC class II on TLR2(+/+) and TLR2(-/-) macrophages from the lungs of individual infected chimeric mice was indistinguishable. These results indicate that TLR2-dependent and -independent mechanisms of inhibition of responses to IFN-gamma are equivalent in vivo, and that M. tuberculosis uses multiple pathways to abrogate the action of an important effector of adaptive immunity. This work was supported by National Institutes of Health Grants AI 065357-AI 020010.
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Affiliation(s)
- Eleanor Z Kincaid
- Division of Infectious Diseases, Department of Medicine, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
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