TLR2 and Arthritis: 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.