Critical role of Toll-like receptor 2 in Bacteroides fragilis-mediated immune responses in murine peritoneal mesothelial cells.

In this study, the role of Toll-like receptor 2 (TLR2) in immune responses of murine peritoneal mesothelial cells against Bacteroides fragilis was investigated. Enzyme linked immunosorbent assay was used to measure cytokines and chemokines. Activation of nuclear factor κB (NF-κB-α) and mitogen-activated protein kinases (MAP kinases) was investigated by western blot analysis. B. fragilis induced production of interleukin-6, chemokine (C-X-C motif) ligand 1 (CXCL1) and chemokine (C-C motif) ligand 2 (CCL2) in wild type peritoneal mesothelial cells; this was impaired in TLR2-deficient cells. In addition, in response to B. fragilis, phosphorylation of inhibitory NF-κB-α and c-Jun N-terminal kinase mitogen-activated protein kinase (MAPK) was induced in wild type mesothelial cells, but not in TLR2-deficient cells,. Inhibitor assay revealed that NF-κB and MAPKs are essential for B. fragilis-induced production of CXCL1 and CCL2 in mesothelial cells. These findings suggest that TLR2 mediates immune responses in peritoneal mesothelial cells in response to B. fragilis.