Complement C5b-9-mediated arachidonic acid metabolism in glomerular epithelial cells : role of cyclooxygenase-1 and -2.
In the passive Heymann nephritis (PHN) model of membranous nephropathy, complement C5b-9 induces glomerular epithelial cell (GEC) injury and proteinuria, which is partially mediated by eicosanoids. This study addresses the role of cyclooxygenase (COX)-1 and -2 in C5b-9-mediated eicosanoid production in GEC. Unstimulated rat GEC in culture primarily express COX-1. When stimulated with sublytic C5b-9, COX-2 was significantly up-regulated, whereas COX-1 was not affected. Compared with control, complement-treated GEC produced 32% more prostaglandin (PG) E(2) in the presence of exogenous substrate, and the increase was abolished with the COX-2-selective inhibitor, NS-398. Release of arachidonic acid from GEC phospholipids via C5b-9-induced activation of cytosolic phospholipase A(2) was associated with a marked stimulation of PGE(2) production, which was inhibited by 60% with NS-398. The results in cultured GEC were extended to GEC injury in vivo by examining COX-1 and -2 expression in PHN. Glomeruli from rats with PHN expressed significantly more COX-1 and COX-2, as compared with normal rats. PGE(2) production in glomeruli of rats with PHN was about twofold greater than in control glomeruli, and the increase was partially inhibited with NS-398. Thus, in GEC in culture and in vivo, C5b-9-induced eicosanoid production is regulated by both isoforms of COX. The inducible COX-2 may be an important novel mediator of C5b-9-induced glomerular injury.
Takano
T
T
Department of Medicine, McGill University Health Centre, Montreal, Quebec, Canada. ttomok@po-box.mcgill.ca
Cybulsky
A V
AV
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D019556:COS Cells; D015938:Complement Membrane Attack Complex / Q000494:pharmacology / Q000502:physiology*; D003165:Complement System Proteins / Q000494:pharmacology; D003470:Culture Media / Q000494:pharmacology; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D004847:Epithelial Cells / Q000378:metabolism; D005921:Glomerulonephritis / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000502:physiology; D007678:Kidney Glomerulus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation
D015938:Complement Membrane Attack Complex; D003470:Culture Media; D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D016718:Arachidonic Acid; D003165:Complement System Proteins; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496513:Ptgs1 protein, rat