Curcumin ( <i>Curcuma longa</i> ) Supplementation Improves Tibiofemoral Joint Outcomes in Low-Dose Prednisone-Treated Experimental Rheumatoid Arthritis

Rheumatoid arthritis is an autoimmune disease that primarily affects synovial joints, mainly in women. This study analyzed the effects of curcumin supplementation combined with prednisone on functionality, lipoperoxidation, inflammatory, and histological characteristics of the tibiofemoral joint and periarticular structures. For this, thirty 18-month-old female Wistar rats were distributed into six groups: control, arthritis, arthritis + curcumin, arthritis + prednisone low-dose, arthritis + prednisone high-dose, and arthritis + prednisone low-dose supplemented with curcumin. Rheumatoid arthritis was experimentally induced via complete Freund's adjuvant injection into the tibiofemoral joint. Treatments were administered by gavage for 14 days: prednisone (2 or 10 mg/kg/day) and curcumin (100 mg/kg/day). Functional, inflammatory, lipoperoxidation, and histological parameters were assessed in the hind paw, blood plasma, and tibiofemoral joint. Generalized mixed and linear models were used for statistical analysis (p = 0.05). Compared to arthritis, low-dose prednisone + curcumin showed significant improvement in lipoperoxidation (p < 0.0001) and leukocyte migration (p = 0.004) and, together with the curcumin group, also showed the most promising results in the semiquantitative assessments of the joint and periarticular structures (p < 0.0001). Thus, treatment with curcumin, alone or combined with low-dose prednisone, restored joint functionality and improved inflammatory, oxidative, and morphological aspects in old female rats with experimentally induced rheumatoid arthritis.