IL6 and rheumatoid arthritis: During the onset of RA, the number of intraarticular FLS increases and the invasion of RA-FLS is enhanced, resulting in the transformation of the synovial lining into an invasive tissue mass.3 In addition, RA-FLS can serve as important immunomodulators in pathogenesis by secreting inflammatory factors (such as interleukin (IL)-6) and interacting with immune cells.