Roles of Cytoplasmic Phospholipase in Expression of the Antimicrobial Activity of Host Macrophages against Mycobacterium tuberculosis Infection

We studied roles of phospholipase A2 (PLA2) isozymes, including type IIA secretory PLA2 (sPLA2-IIA), type IV cytosolic, Ca2+-dependent PLA2 (cPLA2) , type V secretory PLA2 (sPLA2-V) , and type VI cytosolic, Ca2+-independent PLA2 (iPLA2) , in macrophage (Mφ) antimicrobial activity against Mycobacterium tuberculosis (Mtb) H37Ra (avirulent) strain and Mφ mRNA expression of these PLA2 isotypes in response to infection with the microorganisms. First, a cPLA2 inhibitor arachidonyl trifluoromethylketone mildly reduced Mφ anti-Mtb activity, while the other PLA2 inhibitors did not significantly block the Mφ antimycobacterial function, if any. Second, Mφ expression of cPLA2 and sPLA2-V mRNAs was up-regulated during 6 to 12 h after infection with Mtb H37Ra strain. These findings suggest that cPLA2 plays a role in cellular mechanisms participating in the expression of Mφ anti-Mtb activity.