Aqueous extract of Kan-Lu-Hsiao-Tu-Tan ameliorates collagen-induced arthritis in mice by regulating immune and inflammatory responses

Abstract Background Rheumatoid arthritis (RA) is an autoimmune disease featured by joint inflammation and systemic comorbidities. Kan-Lu-Hsiao-Tu-Tan (KLHTT), a Chinese medicine formulation, has free radical scavenging capacity and anti-inflammatory activity in vitro. However, its anti-arthritic effect remains unknown. Herein, we aimed to explore the anti-arthritic effects of KLHTT on collagen-induced arthritis (CIA) in mice and investigate the underlying mechanisms. Methods KLHTT was extracted using boiling water. KLHTT (50 and 100 mg/kg) was fed orally for 21 days once a day on CIA in DBA/1J mice. The severity of CIA was evaluated by histological assessments. Levels of inflammatory cytokines, malondialdehyde (MDA), and hydrogen peroxide (H2O2) were measured using ELISA, thiobarbituric acid reactive substances, and hydrogen peroxide assay kits, respectively. Anti-collagen type II (CII) antibody was assayed by ELISA. Proliferation of splenocytes was tested using radioactive thymidine incorporation assay. Levels of Th1 and Th17 cells were obtained using flow cytometry. Results KLHTT significantly ameliorated paw edema and restored body weight in CIA mice. The synovitis, cartilage damage, and bone erosion were reduced by KLHTT. KLHTT exhibited anti-inflammatory effects by decreasing the levels of interleukin (IL)-1β, IL-6, IL-17A, and tumour necrosis factor-α in the paw homogenates and serum. KLHTT also showed antioxidant activity by reducing the concentrations of MDA and H2O2 in paw tissues. Moreover, KLHTT reduced anti-CII antibody formation, suppressed splenocyte proliferation, and mitigated the levels of splenic Th1 and Th17 cells in CIA mice. Conclusion The therapeutic effects of KLHTT in CIA mice were through regulating immune and inflammatory responses. Our results suggest that KLHTT has potential to treat rheumatoid arthritis.