Therapeutic effect of intra-articular injected 3′-sialyllactose on a minipig model of rheumatoid arthritis induced by collagen

BACKGROUND: Rheumatoid arthritis (RA) is a chronic inflammatory disease of joint, but there is no known cure. 3′-sialyllactose (3′-SL) is an oligosaccharide that is abundant in breast milk of mammals, and has anti-inflammatory properties. However, the efficacy of 3′-SL on RA remains unclear. The objective of the present study was to evaluate the therapeutic effect of 3′-SL after it was directly injected into the knee joint cavity of a RA minipig model. RESULTS: Minipig RA model was induced by intra-articular injection of bovine type II collagen emulsified with complete or incomplete Freund’s adjuvant into left knee joint. In clinical assessment, lameness and swelling of the hindlimb and increased knee joint width were observed in all animals. After the onset of arthritis, 3′-SL (0, 2, 10, and 50 mg/kg) was directly administered to the left knee joint cavity once a week for 4 weeks. Compared to the vehicle control group, no significant difference in macroscopic observation of the synovial pathology or the expression of inflammation-related genes (IL-1β, TNF-α, and COX2) in the synovial membrane of the knee joint was found. In microscopic observation, cell cloning of the articular cartilage was significantly reduced in proportion to the concentration of 3′-SL administered. CONCLUSIONS: Our results suggest that intra-articular injected 3′-SL had a therapeutic effect on collagen-induced arthritis at the cellular level with potential as a medication for RA. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s42826-022-00119-2.