Role of Phospholipases A_2 in Cyclooxygenase-2 Expression Induced by Entamoeba Histolytica in Macrophages

摘要

Expression of cyclooxygenase-2 (COX-2) has been demonstrated in macrophages (MOs) present in amoebic liver abscess. Substrate for COX-2 is released from membrane phospholipids by the action of phospholipase A_2 (PLA_2). To analyze the role of PLA_2 enzymes involved in MOs-COX-2 expression induced by E. histolytica antigens, COX-2 expression was analyzed in MOs treated with inhibitors for cPLA_2 and iPLA_2. Results demonstrated that soluble amoebic proteins, fixed, and viable trophozoites induce COX-2 mRNA in MOs. Additionally, inhibition of cPLA_2 blocked the COX-2 expression induced by cytosolic and secretory antigens, whereas inhibition of iPLA_2 abrogated COX-2 expression mediated by membrane antigens. These results suggest that in the early phase of infection, parasite may use different mechanisms to promote inflammation at local level.