FcgammaRIIa mediates C-reactive protein-induced inflammatory responses of human vascular smooth muscle cells by activating NADPH oxidase 4.
OBJECTIVE
We investigated the mechanism by which C-reactive protein (CRP) affects pro-inflammatory activities of vascular smooth muscle cells (VSMCs).


RESULTS
RT-PCR, flow cytometry, and immunoblotting assays consistently showed the expression of FcgammaRIIa by cultured VSMCs isolated from human coronary arteries. Immunofluorescence staining of human coronary artery plaque showed the co-localization of FcgammaRIIa with alpha-actin(+) VSMCs in atheromatous regions. Confocal microscopic image analysis of H(2)DCFDA-labeled cells showed that CRP induced intracellular reactive oxygen species (ROS) generation by FcgammaRIIa(+) HEK293T cells. Moreover, CRP time- and dose-dependently generated ROS in VSMCs through FcgammaRIIa activation. VSMCs mainly express NADPH oxidase 4 isoform (Nox4), the suppression of which using a specific siRNA completely abolished CRP-induced ROS generation by VSMCs. The downregulation of p22(phox), a component of the active Nox4 complex, by transfecting with specific decoy oligomers and functional blocking of FcgammaRIIa not only inhibited the CRP-induced ROS generation but also reduced the degree of AP-1 and NF-kappaB activation, the production of MCP-1, IL-6, and ET-1, and the apoptotic changes of VSMCs in response to CRP.


CONCLUSIONS
CRP-induced ROS generation by VSMCs, which requires functional activation of FcgammaRIIa and NADPH oxidase 4, orchestrates pro-inflammatory activities of VSMCs and may eventually promote atherogenesis and plaque rupture.
Ryu
Jewon
J
Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
Lee
Cheol Whan
CW
Shin
Jin-Ae
JA
Park
Chan-Sik
CS
Kim
Jae Joong
JJ
Park
Seung-Jung
SJ
Han
Ki Hoon
KH
D000368:Aged; D015703:Antigens, CD / Q000235:genetics / Q000502:physiology*; D017209:Apoptosis; D002097:C-Reactive Protein / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D002460:Cell Line; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000235:genetics; D003327:Coronary Disease / Q000378:metabolism / Q000473:pathology; D003331:Coronary Vessels; D019332:Endothelin-1 / Q000235:genetics; D004789:Enzyme Activation; D005434:Flow Cytometry; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics; D018613:Microscopy, Confocal; D032389:Myocytes, Smooth Muscle / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D000074624:NADPH Oxidase 1; D000074662:NADPH Oxidase 2; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D017452:Receptors, IgG / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018808:Transcription Factor AP-1 / Q000378:metabolism; D051742:Transcription Factor CHOP / Q000235:genetics; D014162:Transfection / Q000379:methods
D015703:Antigens, CD; C111835:CCL2 protein, human; D018932:Chemokine CCL2; C497249:DDIT3 protein, human; D019332:Endothelin-1; C080568:Fc gamma receptor IIA; D015850:Interleukin-6; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D017452:Receptors, IgG; D011994:Recombinant Proteins; D018808:Transcription Factor AP-1; D051742:Transcription Factor CHOP; D002097:C-Reactive Protein; C056558:CYBB protein, human; D000074624:NADPH Oxidase 1; D000074662:NADPH Oxidase 2; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C402799:NOX1 protein, human; C498910:NOX4 protein, human; C086986:CYBA protein, human