Interleukin-1β-induced type IIA secreted phospholipase A2gene expression and extracellular activityin rat vascular endothelial cells

Abstract

Two phospholipase A2(PLA2) isoforms, secretory and cytosolic, have been implicated in inflammation. Secretory type IIA PLA2(sPLA2-IIA), which hydrolyzes fatty acids bound at the sn-2 position of glycerophospholipids, has been detected universally in a variety of mammalian tissues and cells. The expression of the sPLA2-IIA gene and its extracellular activity were shown to be regulated by different factors such as hypoxia, cytokines and phorbol esters. In the present study, we examined the effects of interleukin-1β (IL-1β) on the expression of the 14kDa sPLA2-IIA, determined using reverse transcription polymerase chain reaction and radiometricEscherichia coli enzyme assay in primary cultures of rat endothelial cells and in two different rat endothelial cell lines (SVAREC and RBE4). These experiments revealed that IL-1β induces sPLA2-IIa gene expression and secretion of the enzyme in endothelial cells in a dose- and time-dependent manner. The cAMP-elevator forskolin did not augment the cytokine-induced elevation of sPLA2-IIa enzyme activity but significantly increased the IL-1β-stimulated sPLA2-IIa mRNA contents in endothelial cells.