TNF and Arthritis: Interestingly, in the mouse arthritis model, we found that IL-23 and IL-6 or TNF-α secreted by DCs were positively correlated with Th17 or Th1 cells (p < 0.001) (Figure 4D), indicating that PIC may inhibit the polarization of CD4+ T cells into pro-inflammatory Th1 and Th17 cells by impeding DCs’ production of inflammatory cytokines.