A joint research team led by Professor Bae Yoe-sik of Sungkyunkwan University (SKKU)’s Department of Biological Sciences and Professor Kim Hong-hee of Seoul National University’s School of Dentistry has identified a new treatment mechanism for rheumatoid arthritis. The study provides important insight into why existing therapies are ineffective for certain patients and offers a new therapeutic approach. Rheumatoid arthritis is an autoimmune disease in which the immune system mistakenly attacks the joints, causing chronic inflammation and pain. Currently, antibody treatments that target Tumor Necrosis Factor (TNF), a key inflammatory molecule, are commonly used, but some patients do not respond to this treatment or relapse after a while. The team’s analysis of patients’ joint tissues revealed that macrophages, a type of white blood cell, play a central role in this problem. Normally, macrophages act as cleaners, removing dead cell debris and reducing inflammation. However, when they overproduce a protein called Salt-Inducible Kinase 3 (SIK3), they lose their cleaning role and instead activate other immune cells, worsening inflammation. The study found that well-responding patients had fewer of these malfunctionin macrophages, while non-responding patients retained many. Restoring the cleaning function of macrophages reduced inflammation and helped rebalance the immune system, indicating that effective treatment should not only suppress inflammation but also revive the body’s natural recovery process. The research team hopes that this discovery will pave the way for personalized therapies and potentially lead to fundamental cures for rheumatoid arthritis in the future.