IL6 and rheumatoid arthritis: To investigate its potential effects on the cytokines from macrophages, a LPS-treated, PMA-differentiated THP-1 cell culture model was used in this study, because the LPS treatment can induce macrophage-like PMA-differentiated THP-1 cells to the M1-like status cells, which are often found under several inflammatory disease conditions, including RA, liver disease and viral infection, and produce several inflammatory cytokines (e.g., IL-6, IL-1beta and TNF-alpha) [26,27,39,40,41,42,43,44].