A phospholipase A2 from Bothrops asper snake venom activates neutrophils in culture: Expression of cyclooxygenase-2 and PGE2 biosynthesis

In this study, the production of prostaglandin E2 (PGE2) and up-regulation in cyclooxygenase (COX) pathway induced by a phospholipase A2 (PLA2), myotoxin-III (MT-III), purified from Bothrops asper snake venom, in isolated neutrophils were investigated. The arachidonic acid (AA) production and the participation of intracellular PLA2s (cytosolic PLA2 and Ca2+-independent PLA2) in these events were also evaluated. MT-III induced COX-2, but not COX-1 gene and protein expression in neutrophils and increased PGE2 levels. Pretreatment of neutrophils with COX-2 and COX-1 inhibitors reduced PGE2 production induced by MT-III. Arachidonyl trifluoromethyl ketone (AACOCF3), an intracellular PLA2 inhibitor, but not bromoenol lactone (BEL), an iPLA2 inhibitor, suppressed the MT-III-induced AA and PGE2 release. In conclusion, MT-III directly stimulates neutrophils inducing COX-2 mRNA and protein expression followed by production of PGE2. COX-2 isoform is preeminent over COX-1 for production of PGE2 stimulated by MT-III. PGE2 and AA release by MT-III probably is related to cPLA2 activation.