title: 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/10(6) 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.
authors.affiliation: Division of Rheumatology, Allergy and Immunology, Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA 23298, USA. yfukuoka@vcu.edu
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fukuoka
authors.forename: Michelle R
authors.initials: MR
authors.lastname: Hite
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Dellinger
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Schwartz
mesh_terms: D002478:Cells, Cultured; D003176:Complement C3 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D015926:Complement C3a / Q000096:biosynthesis; D003179:Complement C3b / Q000096:biosynthesis; D003182:Complement C5 / Q000096:biosynthesis* / Q000235:genetics; D017077:Culture Media, Conditioned / Q000737:chemistry; D004357:Drug Synergism; D006801:Humans; D007378:Interleukins / Q000494:pharmacology; D008168:Lung / Q000166:cytology; D008407:Mast Cells / Q000378:metabolism*; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D012867:Skin / Q000166:cytology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D053802:Tryptases / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000494:pharmacology; D020298:U937 Cells
chemical_list: D003176:Complement C3; D003182:Complement C5; D017077:Culture Media, Conditioned; D007378:Interleukins; D016328:NF-kappa B; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D015926:Complement C3a; D003179:Complement C3b; D053802:Tryptases; D013755:Tetradecanoylphorbol Acetate