AbstractIn previous studies, we have shown that reactive oxygen species (ROS)‐mediated inflammatory signaling is essential for microglial proinflammatory responses toMycobacterium tuberculosis(Mtb). To further investigate the molecular mechanisms governing these processes, we sought to describe the role of phospholipase A2(PLA2) in Mtb‐induced ROS generation and inflammatory mediator release by microglia. Inhibition of secretory PLA2(sPLA2), but not cytosolic PLA2(cPLA2), profoundly abrogated Mtb‐mediated ROS release, the generation of various inflammatory mediators (tumor necrosis factor, interleukin‐6, cyclooxygenase‐2, inducible nitric oxide synthase, and matrix metalloproteinase‐2 and −9), and the activation of nuclear factor (NF)‐κB and MAPKs (ERK1/2, p38, and JNK/SAPK) by murine microglial BV‐2 cells or primary mixed glial cells. Interruption of the Ras/Raf‐1/MEK1/ERK1/2 pathway abolished Mtb‐induced sPLA2activity, whereas the blockage of JNK/SAPK or p38 activity had no effect. Specific inhibition of sPLA2, but not cPLA2, suppressed the upregulation of ERK1/2 phosphorylation by Mtb stimulation, suggesting the existence of a mutual dependency between the ERK1/2 and sPLA2pathways. Moreover, examination of the protein kinase C (PKC) family revealed that classical PKCs are involved in Mtb‐induced sPLA2activation by microglia. Taken together, our results demonstrate for the first time that sPLA2, either through pathways comprising Ras/Raf‐1/MEK1/ERK1/2 or the classical PKC family, plays an essential role in Mtb‐mediated ROS generation and inflammatory mediator release by microglial cells. © 2008 Wiley‐Liss, Inc.