1 In rat mesangial cells extracellular nucleotides were found to increase arachidonic acid release by a cytosolic phospholipase A 2 through the P2Y 2 purinergic receptor. 2 In this study we investigated the eects of ATP and UTP on interleukin-1b (IL-1b)-induced mRNA expression and activity of group IIA phospholipase A 2 (sPLA 2 -IIA) in rat mesangial cells. 3 Treatment of cells for 24 h with extracellular ATP potentiated IL-1b-stimulated sPLA 2 -IIA induction, whereas UTP had no eect. 4 We obtained the following evidence that the P2Y 2 receptor is not involved in the potentiation of sPLA 2 -IIA induction: (i) ATP-g-S had no enhancing eect; (ii) suramin, a P 2 receptor antagonist, did not inhibit ATP-mediated potentiation; (iii) inhibition of degradation of extracellular nucleotides by the 5'-ectonucleotidase inhibitor AOPCP did not enhance sPLA 2 -IIA induction and (iv) adenosine deaminase treatment completely abolished the ATP-mediated potentiation of sPLA 2 -IIA induction. 5 In contrast, treatment of mesangial cells with adenosine or the A2A receptor agonist CGS 21680 mimicked the eects of ATP in enhancing IL-1b-stimulated sPLA 2 -IIA induction, whereas the speci®c A2A receptor antagonist ZM 241385 completely abolished the potentiating eect of ATP or adenosine. 6 The protein kinase A inhibitor Rp-8-Br-cyclic AMPS dose-dependently inhibited the enhancing eect of ATP or adenosine indicating the participation of an adenosine receptor-mediated cyclic AMP-dependent signalling pathway. 7 These data indicate that ATP mediates proin¯ammatory long-term eects in rat mesangial cells via its degradation product adenosine through the A2A receptor resulting in potentiation of sPLA 2 -IIA induction.

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 aected. 2 In mesangial cells, in addition to inhibition of catalytic activity, the membrane-permeant CGP-43182 completely blocked interleukin 1b (IL1b)-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 IL1b-induced gene expression of the inducible nitric oxide synthase, leading to an inhibition of cytokine-stimulated nitric oxide formation. 5 In contrast, the stimulatory eect 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 IL1b-but not cyclic AMP-activated transcriptional regulation. 6 By studying components of the upstream transcription machinery, we observed an inhibition of NFkB activation by CGP-43182 in IL1b-treated cells. Moreover, we observed that CGP-43182 prevented the phosphorylation and proteolytic degradation of the endogenous NFkB inhibitor, IkB, a process necessary for NFkB activation. 7 From our data, we propose that CGP-43182 is a potent anti-in¯ammatory drug useful for preventing the consequences of a concerted action of cytokine-stimulated pro-in¯ammatory genes mediated by NFkB.

Pyr-1, 3-(2,6-dichlorophenylsulfonylamino)-4-(2-(4-acetamido)pyridyl)-5-(3-(4-¯uorophenoxy)benzyl(thio)-(1H)-pyrazole; sPLA 2 , secreted phospholipase A 2 .

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