IL6 and rheumatoid arthritis: Our previous research showed that circ-CBLB inhibited the proliferation of RA-FLS, promoted their apoptosis, and modulated cytokine levels by increasing the production of anti-inflammatory cytokines, such as IL-4 and IL-10, while decreasing the levels of pro-inflammatory cytokines, including IL-6 and TNF-α (20, 37).