Inhibition of NFkappaB-mediated pro-inflammatory gene expression in rat mesangial cells by the enolized...

1. CGP-43182 has been described as a potent inhibitor of group IIA secreted phospholipase A(2) (group IIA sPLA(2)) activity in vitro. In rat mesangial cells, inhibition of group IIA sPLA(2) activity by CGP-43182 results in a 70% reduction of cytokine-stimulated prostaglandin E(2) biosynthesis, suggesting that group IIA sPLA(2) participates in arachidonic acid release and eicosanoid formation. Under these conditions the cytosolic phospholipase A(2) is not affected. 2. In mesangial cells, in addition to inhibition of catalytic activity, the membrane-permeant CGP-43182 completely blocked interleukin 1beta (IL1beta)-stimulated group IIA sPLA(2) gene expression. 3. A further action of CGP-43182 was a complete inhibition of cyclo-oxygenase-2 gene expression, resulting in a drastic reduction of prostaglandin formation in mesangial cells. 4. Moreover, CGP-43182 completely blocked IL1beta-induced gene expression of the inducible nitric oxide synthase, leading to an inhibition of cytokine-stimulated nitric oxide formation. 5. In contrast, the stimulatory effect of the cell-permeant cyclic AMP-analogue, dibutyryl-cAMP, on the induction of these enzymes was not inhibited by CGP-43182. These data indicate that CGP-43182 interferes with IL1beta- but not cyclic AMP-activated transcriptional regulation. 6. By studying components of the upstream transcription machinery, we observed an inhibition of NFkappaB activation by CGP-43182 in IL1beta-treated cells. Moreover, we observed that CGP-43182 prevented the phosphorylation and proteolytic degradation of the endogenous NFkappaB inhibitor, IkappaB, a process necessary for NFkappaB activation. 7. From our data, we propose that CGP-43182 is a potent anti-inflammatory drug useful for preventing the consequences of a concerted action of cytokine-stimulated pro-inflammatory genes mediated by NFkappaB.