Group X secretory phospholipase A2 can induce arachidonic acid release and eicosanoid production without activation of cytosolic phospholipase A2 alpha

Group X secretory phospholipase A2 (sPLA2-X) and cytosolic phospholipase A2 alpha (cPLA2α) are involved in the release of arachidonic acid (AA) from membrane phospholipids linked to the eicosanoid production in various pathological states. Recent studies have indicated the presence of various types of cross-talk between sPLA2s and cPLA2α resulting in effective AA release. Here we examined the dependence of sPLA2-X-induced potent AA release on the cPLA2α activation by using specific cPLA2α or sPLA2 inhibitors as well as cPLA2α-deficient mice. We found that Pyrrophenone, a cPLA2α-specific inhibitor, did not suppress the sPLA2-X-induced potent AA release and prostaglandin E2 formation in mouse spleen cells. Furthermore, the amount of AA released by sPLA2-X from spleen cells was not significantly altered by cPLA2α deficiency. These results suggest that sPLA2-X induces potent AA release without activation of cPLA2α, which might be relevant to eicosanoid production in some pathological states where cPLA2α is not activated.