Serum IL-41 levels in Rheumatoid Arthritis Patients: Relationship with Disease Activity and Radiological Scores

Background: IL-41 is regarded as an anti-inflammatory cytokine linked to several inflammatory conditions including arthritis, sepsis, colitis and chronic obstructive pulmonary disease. This research aimed to evaluate serum IL-41 titer in cases with rheumatoid arthritis (RA) and to explore the relationship between IL-41 titer and disease activity (DA), along with radiological assessments including musculoskeletal ultrasound. Methods: This case-control research included 80 participants divided into two groups: Group A (RA cases) and Group B (age- and sex-matched healthy controls). Results: Serum IL-41 titer is elevated in the RA group than control one with a significant p< 0.001. IL-41 demonstrated a significant positive correlation with multiple clinical and inflammatory markers, including HAQ, VAS, swollen and tender joint counts, DA and functional impairment (components of RASS), DAS28, and ESR (p< 0.001). Conclusion: IL-41 demonstrated strong capability to differentiate RA cases from healthy individuals and to distinguish between high and low DA states. These observations suggest IL-41 may act as a valuable biomarker for diagnosing RA and monitoring DA. The absence of correlation with radiological measures indicates that IL-41 primarily reflects inflammatory activity rather than structural joint damage.