Induction of C3 and CCL2 by C3a in keratinocytes: a novel autocrine amplification loop of inflammatory skin reactions.
The complement fragment-3a (C3a) acts via a G protein-coupled C3aR and is of importance in allergic and inflammatory diseases. Recent studies suggest the presence of complement proteins in the epidermal compartment and synthesis of some of these proteins (C3, factor B, and factor H) by human primary keratinocytes (KCs) during inflammation. However, expression of C3aR and its role in human KCs is not elucidated thus far. In this study, we demonstrate the expression of C3aR on KCs as detected by quantitative real-time RT-PCR and flow cytometry. IFN-gamma and IFN-alpha strongly up-regulated the surface expression of C3aR on KCs among all other cytokines tested. After up-regulation of C3aR by IFN-gamma and IFN-alpha, we observed the induction of five genes (CCL2, CCL5, CXCL8, CXCL10, and C3) after stimulation of KCs with C3a in microarray analysis. We confirmed the induction of C3 and CCL2 at RNA and protein levels. Furthermore, incubation of C3 with skin mast cells tryptase resulted in the generation of C3 fragments with C3a activity. In conclusion, our data illustrate that epidermal KCs express functional C3aR. The increases of C3 and CCL2 synthesis by C3a and C3 activation by skin mast cell tryptase delineates a novel amplification loop of complement activation and inflammatory responses that may influence the pathogenesis of allergic/inflammatory skin diseases.
Purwar
Rahul
R
Department of Dermatology and Allergology, Hannover Medical University, Ricklinger Strasse 05, D-30449 Hannover, Germany. purwar.rahul@mh-hannover.de
Wittmann
Miriam
M
Zwirner
Jörg
J
Oppermann
Martin
M
Kracht
Michael
M
Dittrich-Breiholz
Oliver
O
Gutzmer
Ralf
R
Werfel
Thomas
T
D019898:Autocrine Communication / Q000276:immunology; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism*; D003167:Complement Activation / Q000502:physiology; D003176:Complement C3 / Q000378:metabolism*; D015926:Complement C3a / Q000378:metabolism*; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D024202:Electrophoretic Mobility Shift Assay; D005434:Flow Cytometry; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D007249:Inflammation / Q000276:immunology* / Q000473:pathology; D015603:Keratinocytes / Q000276:immunology / Q000378:metabolism*; D016177:Macrophage-1 Antigen / Q000378:metabolism; D008407:Mast Cells / Q000201:enzymology; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012697:Serine Endopeptidases / Q000378:metabolism; D012867:Skin / Q000166:cytology / Q000276:immunology* / Q000473:pathology; D053802:Tryptases
C111835:CCL2 protein, human; D018932:Chemokine CCL2; D003176:Complement C3; D016207:Cytokines; D016177:Macrophage-1 Antigen; D015926:Complement C3a; D012697:Serine Endopeptidases; D053802:Tryptases