Mycobacterium tuberculosis Rv0652 stimulates production of tumour necrosis factor and monocytes chemoattractant protein‐1 in macrophages through the Toll‐like receptor 4 pathway

Summary Mycobacterial proteins interact with host macrophages and modulate their functions and cytokine gene expression profile. The protein Rv0652 is abundant in culture filtrates of Mycobacterium tuberculosis K‐strain, which belongs to the Beijing family, compared with levels in the H37Rv and CDC1551 strains. Rv0652 induces strong antibody responses in patients with active tuberculosis. We investigated pro‐inflammatory cytokine production induced by Rv0652 in murine macrophages and the roles of signalling pathways. In RAW264.7 cells and bone marrow‐derived macrophages, recombinant Rv0652 induced predominantly tumour necrosis factor (TNF) and monocyte chemoattractant protein (MCP)‐1 production, which was dependent on mitogen‐activated protein kinases and nuclear factor‐κB. Specific signalling pathway inhibitors revealed that the extracellular signal‐regulated kinase 1/2 (ERK1/2), p38 and phosphatidylinositol 3‐kinase (PI3K) pathways were essential for Rv0652‐induced TNF production, whereas the ERK1/2 and PI3K pathways, but not the p38 pathway, were critical for MCP‐1 production in macrophages. Rv0652‐stimulated TNF and MCP‐1 secretion by macrophages occurred in a Toll‐like receptor 4‐dependent and MyD88‐dependent manner. In addition, Rv0652 significantly up‐regulated the expression of the mannose receptor, CD80, CD86 and MHC class II molecules. These results suggest that Rv0652 can induce a protective immunity against M. tuberculosis through the macrophage activation.