期刊
MEDIATORS OF INFLAMMATION
卷 2016, 期 -, 页码 -出版社
HINDAWI LTD
DOI: 10.1155/2016/1340156
关键词
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资金
- National Institutes of Health [NHLBI-T32-HL007517-29, GM-29507, GM-61656]
- National Science Foundation
- NATIONAL HEART, LUNG, AND BLOOD INSTITUTE [T32HL007517] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES [R01GM029507, R37GM029507, R01GM061656] Funding Source: NIH RePORTER
C5a is an inflammatory mediator generated by complement activation that positively regulates various arms of immune defense, includingToll-like receptor 4 (TLR4) signaling. TheNOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome is activated by pathogen products and cellular/tissue damage products and is a major contributor of IL-1 beta In this study, we investigate whether C5a modulates lipopolysaccharide- (LPS-) induced NLRP3 inflammasome activation in myeloid cells. Appearance of plasma IL-1 beta during endotoxemia was reduced in C5aR1(-/-) mice when compared to wild-type mice. In vitro, C5a significantly enhanced LPS-induced production of IL-1 beta in bone marrow Ly6C-high inflammatory monocytes, accompanied by augmented intracellular pro-IL-1 beta expression. This effect was abolished during p38 blockade by SB 203580 and in the absence of C5aR1. Conversely, C5a suppressed LPS-induced macrophage production of IL-1 beta, which was accompanied by attenuated levels of pro-IL-1 beta, NLRP3, and caspase-1 expression. C5a's suppressive effects were negated during phosphoinositide 3-kinase (PI3K) inhibition by wortmannin but were largely preserved in the absence of C5aR1. Thus, C5a bidirectionally amplifies TLR4-mediated NLRP3 inflammasome activation in monocytes while suppressing this pathway in macrophages. However, as C5aR1 deficiency attenuates the IL-1 beta response to LPS challenge in vivo, our results suggest overall that C5a augments physiologic inflammasome responses.
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