| Mycobacterium tuberculosis Hip1 dampens macrophage proinflammatory responses by limiting toll-like receptor 2 activation. | |
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MedLine Citation:
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PMID: 21947769 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Mycobacterium tuberculosis is a highly successful human pathogen that evades host innate immunity by interfering with macrophage functions. In addition to avoiding macrophage microbicidal activities, M. tuberculosis triggers secretion of proinflammatory cytokines and chemokines in macrophages. The levels of proinflammatory cytokines induced by clinical M. tuberculosis isolates are thought to play an important role in determining tuberculosis disease progression and severity, but the mechanisms by which M. tuberculosis modulates the magnitude of inflammatory responses remain unclear. Here we show that M. tuberculosis restricts robust macrophage activation and dampens proinflammatory responses through the cell envelope-associated serine hydrolase Hip1 (hydrolase important for pathogenesis 1). By transcriptionally profiling macrophages infected with either wild-type or hip1 mutant bacteria, we found that the hip1 mutant induced earlier and significantly higher levels of several proinflammatory cytokines and chemokines. We show that increased activation of Toll-like receptor 2 (TLR2)- and MyD88-dependent signaling pathways mediates the enhanced cytokine secretion induced by the hip1 mutant. Thus, Hip1 restricts the onset and magnitude of proinflammatory cytokines by limiting TLR2-dependent activation. We also show that Hip1 dampens TLR2-independent activation of the inflammasome and limits secretion of interleukin-18 (IL-18). Dampening of TLR2 signaling does not require viable M. tuberculosis or phagocytosis but does require Hip1 catalytic activity. We propose that M. tuberculosis restricts proinflammatory responses by masking cell surface interactions between TLR2 agonists on M. tuberculosis and TLR2 on macrophages. This strategy may allow M. tuberculosis to evade early detection by host immunity, delay the onset of adaptive immune responses, and accelerate disease progression. |
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Authors:
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Ranjna Madan-Lala; Katia Vitorello Peixoto; Fabio Re; Jyothi Rengarajan |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural Date: 2011-09-26 |
Journal Detail:
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Title: Infection and immunity Volume: 79 ISSN: 1098-5522 ISO Abbreviation: Infect. Immun. Publication Date: 2011 Dec |
Date Detail:
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Created Date: 2011-11-14 Completed Date: 2012-01-13 Revised Date: 2013-05-23 |
Medline Journal Info:
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Nlm Unique ID: 0246127 Medline TA: Infect Immun Country: United States |
Other Details:
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Languages: eng Pagination: 4828-38 Citation Subset: IM |
Affiliation:
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Emory Vaccine Center, Emory University, Atlanta, GA 30329, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Bacterial Proteins / metabolism* Carrier Proteins / genetics, metabolism Cells, Cultured Gene Expression Regulation / drug effects* Macrophages / drug effects*, physiology* Mice Mice, Knockout Mycobacterium tuberculosis / metabolism* Myeloid Differentiation Factor 88 / genetics, metabolism Signal Transduction Toll-Like Receptor 2 / genetics, metabolism* |
| Grant Support | |
ID/Acronym/Agency:
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5R01AI083366-02/AI/NIAID NIH HHS; R00TW008043-04/TW/FIC NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Bacterial Proteins; 0/CIAS1 protein, mouse; 0/Carrier Proteins; 0/Myd88 protein, mouse; 0/Myeloid Differentiation Factor 88; 0/Tlr2 protein, mouse; 0/Toll-Like Receptor 2 |
| Comments/Corrections | |
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