Cytosolic group IVa phospholipase A2mediates IL-8/CXCL8-induced transmigration of human polymorphonuclear leukocytes in vitro

Background. cytosolic givapla2is a critical enzyme in the generation of arachidonate metabolites and in induction of 2-integrin adhesion in granulocytes. we hypothesized that givapla2activation also is an essential downstream step for post adhesive migration of pmn in vitro. methods. migration of pmns caused by il-8/cxcl8 was assessed using a transwell migration chamber. pmns were pretreated with two structurally unrelated inhibitors of givapla2,arachidonyl trifluoromethylketone (tfmk) or pyrrophenone,prior to il-8/cxcl8 exposure. the fraction of migrated pmns present in the lower chamber was measured as total myeloperoxidase content. givapla2enzyme activity was analyzed using [14c-papc] as specific substrate f-actin polymerization and cell structure were examined after rhodamine-phalloidin staining. results. il-8/cxcl8-induced migration of pmns was elicited in concentration- and time-dependent manner. time-related phosphorylation and translocation of cytosolic givapla2to the nucleus was observed for pmns stimulated with il-8/cxcl8 in concentration sufficient to cause upstream phosphorylation of mapks (erk-1/2 and p38) and akt/pkb. inhibition of givapla2corresponded to the magnitude of blockade of pmn migration. neither aa nor ltb4secretion was elicited following il-8/cxcl8 activation. in unstimulated pmns,f-actin was located diffusely in the cytosol; however,a clear polarized morphology with f-actin-rich ruffles around the edges of the cell was observed after activation with il-8/cxcl8. inhibition of givapla2blocked change in cell shape and migration caused by il-8/cxcl8 but did not cause f-actin polymerization or translocation of cytosolic f-actin to inner leaflet of the pmn membrane. conclusion. we demonstrate that il-8/cxcl8 causes a) phosphorylation and translocation of cytosolic givapla2to the nucleus,b) change in cell shape,c) polymerization of f-actin,and d) chemoattractant/migration of pmn in vitro. inhibition of givapla2blocks the deformability and subsequent migration of pmns caused by il-8/cxcl8. our data suggest that activation of givapla2is an essential step in pmn migration in vitro. © 2010 meliton et al; licensee biomed central ltd.