Abstract
The complement system and the Toll-like receptors (TLRs) are two central arms of innate immunity that are critical to host defense as well as the development of adaptive immunity. Most pathogens activate both complement and TLRs, suggesting the potential for crosstalk between the two systems. We show here that the complement-derived C5a anaphylatoxin negatively regulates TLR4- and CD40-induced synthesis of IL-12 family cytokines (IL-12, IL-23, and IL-27) from inflammatory macrophages (Mφs) by extracellular signal-regulated kinase- and phosphoinositide 3 kinase-dependent pathways. This decreased cytokine response translates into a decreased T helper type 1 (Th1) response in vitro and in vivo. Accordingly, we found enhanced Th1 immunity in C5a receptor-deficient mice, something that conferred protection from Leishmania major infection. Our findings identify the negative impact of C5a on IL-12 family cytokines as an important mechanism for regulating Th1 polarization in response to innate and adaptive immune network activation.
| Original language | English |
|---|---|
| Journal | Immunity |
| Volume | 22 |
| Issue number | 4 |
| Pages (from-to) | 415-426 |
| Number of pages | 12 |
| ISSN | 1074-7613 |
| DOIs | |
| Publication status | Published - 01.01.2005 |
Funding
We thank L.M. Flick for her help with the LAL assay and C.L. Karp for helpful discussions and critically reading the manuscript. This work was supported by Cincinnati Children’s Hospital Research Foundation funding (to J.K.). H.H. and R.B. were supported by Research Fellowships from Deutsche Forschungsgemeinschaft.
UN SDGs
This output contributes to the following UN Sustainable Development Goals (SDGs)
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SDG 3 Good Health and Well-being
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