STAT3 and rheumatoid arthritis: Theophylline is an anti-inflammatory substance, and previous studies have shown that theophylline can reduce the levels of IL-6, COMP, JAK2, STAT3, RANKL, iNOS, and eNOS by modulating the JAK/STAT/RANKL signaling pathway, thereby alleviating the inflammatory response in rheumatoid arthritis [31].