MyD88–BLT2-dependent cascade contributes to LPS-induced interleukin-6 production in mouse macrophage

Abstract

Endotoxic responses to bacterial lipopolysaccharide (LPS) are triggered by Toll-like receptor 4 (TLR4) and involve the production of inflammatory mediators, including interleukin-6 (IL-6), by macrophages. The detailed mechanism of IL-6 production by macrophages in response to LPS has remained unclear, however. We now show that LPS induces IL-6 synthesis in mouse peritoneal macrophages via the leukotriene B4 receptor BLT2. Our results suggest that TLR4–MyD88 signaling functions upstream of BLT2 and that the generation of reactive oxygen species (ROS) by NADPH oxidase 1 (Nox1) and consequent activation of the transcription factor nuclear factor (NF)-κB function downstream of BLT2 in this response. These results suggest that a TLR4–MyD88–BLT2–Nox1–ROS–NF-κB pathway contributes to the synthesis of IL-6 in LPS-stimulated mouse macrophages.