Interestingly, with regards to the effect of TLR2, we observed that TLR2−/− mice inoculated with the Newman parental strain developed significantly more severe clinical arthritis than the WT mice infected with the same strain (P = 0.02 on day 7, and P = 0.05 on day 10; Fig. 1A), whereas there was no difference when Δlgt mutant strain was used, indicating that TLR2 deficiency aggravates arthritis only in the presence of Lpp. This evidence concerns the gene TLR2 and arthritic joint disease.