CYTOSOLIC PHOSPHOLIPASE A(2) AND CYCLOOXYGENASE-2 MEDIATE RELEASE ANDMETABOLISM OF ARACHIDONIC-ACID IN TUMOR NECROSIS FACTOR-ALPHA-PRIMED CULTURED INTESTINAL EPITHELIAL-CELLS (INT-407)

Background: We have recently reported that tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine that has been suggested to p lay a role in the pathogenesis of inflammatory bowel disease, potentia tes phospholipase A(2) (PLA(2))-stimulated arachidonic acid (AA) relea se and prostaglandin E(2) (PGE(2)) formation in cultured intestinal ep ithelial cells (INT 407). The aim of the present study was to investig ate which particular isoforms of PLA(2) and cyclooxygenase (COX) are i nvolved in these processes. Methods: Cells were labeled with C-14-AA o r C-14-oleic acid, and the amounts of released fatty acid and PGE(2) w ere analyzed by thin-layer chromatography. mRNA was analyzed by revers e transcription and polymerase chain reaction. Results: The cells cont ained mainly mRNA for cytosolic PLA(2) (cPLA(2)) and only trace amount s of mRNA for group I and II. PLA(2). TNF-alpha potentiated the releas e of C-14-AA but not of C-14-oleic acid. The TNF-alpha-potentiated PGE (2) release was reduced after inhibition of cellular COX activity or m RNA synthesis. TNF-alpha increased the amounts of mRNA for COX-2 but n ot for COX-1. Conclusions: The results point to the possibility that T NF-alpha may modulate the intestinal mucosal content of biologically a ctive AA metabolites by priming cPLA(2)- and COX-2-mediated processes in the epithelial cells.