Human Skin Mast Cells Express Complement Factors C3 and C5

Abstract

We examine whether complement factor C3 or C5 is synthesized by human skin–derived mast cells and whether their synthesis is regulated by cytokines. C3 and C5 mRNAs were assessed by RT-PCR, and proteins by flow cytometry, confocal microscopy, Western blotting, and ELISA. C3 and C5 mRNAs were each expressed, and baseline protein levels/106 cultured mast cells were 0.9 and 0.8 ng, respectively, and located in the cytoplasm outside of secretory granules. C3 accumulated in mast cell culture medium over time and by 3 d reached a concentration of 9.4 ± 8.0 ng/ml, whereas C5 levels were not detectable (<0.15 ng/ml). Three-day incubations of mast cells with IL-1α, IL-1β, IL-17, IFN-γ, IL-6, or anti-FcεRI did not affect C3 protein levels in culture medium, whereas incubations with PMA, TNF-α, IL-13, or IL-4 enhanced levels of C3 1.7- to 3.3-fold. In contrast with C3, levels of C5 remained undetectable. Importantly, treatment with TNF-α together with either IL-4 or IL-13 synergistically enhanced C3 (but not C5) production in culture medium by 9.8- or 7.1-fold, respectively. This synergy was blocked by attenuating the TNF-α pathway with neutralizing anti–TNF-α Ab, soluble TNFR, or an inhibitor of NF-κB, or by attenuating the IL-4/13 pathway with Jak family or Erk antagonists. Inhibitors of PI3K, Jnk, and p38 MAPK did not affect this synergy. Thus, human mast cells can produce and secrete C3, whereas β-tryptase can act on C3 to generate C3a and C3b, raising the likelihood that mast cells engage complement to modulate immunity and inflammation in vivo.

Complement Is a Central Mediator of Radiotherapy-Induced Tumor-Specific Immunity and Clinical Response

“…The classical and alternative pathways are the main pathways induced by radiotherapy on the transcriptional level ( Figures 1D and S1C). Because NF-kB, JAK, and STAT transcriptional pathways (Chen et al, 2011;Fukuoka et al, 2013;Hasegawa et al, 2014;Huang et al, 2002), as well as S100 calcium-binding proteins A8 and A9 (S100A8, S100A9) (Schonthaler et al, 2013) are involved in the transcription of complement factors, we analyzed such pathways by immuno-blot and found an increased production of STAT 1, STAT 2, STAT 3, NF-kB, and JAK and increased phosphorylation of STAT 2, STAT3, and JAK ( Figure S1D) 4 hr, but not (A-E) Mice were injected with B16F10-OVA cells and received radiotherapy 12 days later. (A) Tumor growth curves, (n = 5 mice per group).…”

Inflammaging in Skin and Other Tissues - The Roles of Complement System and Macrophage

“…Complement is known to be expressed in a variety of skin cells, such as mast cells [93], macrophages [94], keratinocytes [95] and fibroblasts [96]. This suggests skin has its own complement synthesis system, like retina and vessel wall (see above).…”

Production of complement components by cells of the immune system

“…From mast cells different subsets exist, which are often classified based upon the presence of the serine proteases tryptase and chymase. It was demonstrated that different subsets of MC express C5 and C3 [46,47]. Human skin mast cells showed a diffuse cytoplasmic labelling of both C3…”