The novel receptor C5aR2 is required for C5a-mediated human mast cell adhesion, migration, and proinflammatory mediator production

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Journal titleJournal of Immunology
Pages27742787; # of pages: 14
SubjectCD34 antigen; complement component C5a receptor; complement component C5a receptor 1; complement component C5a receptor 2; gamma interferon inducible protein 10; granulocyte macrophage colony stimulating factor; mitogen activated protein kinase; monocyte chemotactic protein 1; small interfering RNA; stem cell factor; tumor necrosis factor; unclassified drug; cell adhesion; cell migration; cell surface; chemotaxis; controlled study; cytokine production; enzyme phosphorylation; internalization; mast cell degranulation; protein determination; protein expression; protein function; protein secretion; signal transduction
AbstractC5a generated during complement activation possesses proinflammatory and immunoregulatory properties critical for the development and modulation of allergic immune responses. In immune cells, C5a mediates its effects through binding to two G protein-coupled receptors, C5aR1 and C5aR2. Mast cells are key effectors in allergic reactions, and decades of research have suggested that the majority of C5a effects on mast cells are mediated through C5aR1, whereas the expression and function of C5aR2 have not been explored. We demonstrated that the human mast cell line Laboratory of Allergic Diseases 2 (LAD2) expresses surface C5aR2 but not C5aR1, whereas CD34+ cell-derived primary mast cells do not express surface C5aR1 or C5aR2. Stem cell factor and IL-4 upregulated C5aR2 expression on LAD2 cells. Furthermore, C5a caused internalization of LAD2 cell-surface C5aR2.We therefore used LAD2 cells as a model to study C5a/C5aR2-induced biological responses and signaling in human mast cells. We found that whereas C5a was unable to induce degranulation, it stimulated GM-CSF, TNF, CXCL10, and CCL2 production. C5a caused ERK phosphorylation, a signaling molecule important in cytokine and chemokine generation. In addition, C5a stimulated adhesion and chemotaxis of mast cells.Wortmannin, an inhibitor of PI3K, and small interfering RNA against b-arrestin-2 blocked C5a-induced adhesion. Silencing of C5aR2 using lentiviral short hairpin RNA rendered the cells unresponsive to C5a-induced adhesion, chemotaxis, and mediator release, as well as ERK phosphorylation. Overall, this study reveals a novel role for C5aR2 in C5a-mediated activation of mast cells and demonstrates that C5aR2 ligation initiates a b-arrestin-2-, PI3K-, and ERK-dependent signaling pathway in these cells.
Publication date
PublisherThe American Association of Immunologists
AffiliationNational Research Council Canada (NRC-CNRC); National Institute for Nanotechnology
Peer reviewedYes
NPARC number21276945
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Record identifierfd374abd-0e89-46f1-84cb-dd93f63703e0
Record created2015-11-10
Record modified2016-05-09
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