Dietary alpha lipoic acid supplementation prevents synovial inflammation and bone destruction in collagen-induced arthritic mice

Rheumatoid arthritis (RA) is a chronic inflammatory disorder characterized by chronic inflammation and joint destruction. In this study, we investigated whether dietary supplementation with alpha lipoic acid (ALA) suppresses collagen-induced arthritis (CIA) in mice. Mice were randomly divided into three groups: (1) a control CIA group was fed a normal diet, (2) a CIA group was fed a 0.1% ALA diet (average ALA intake of 160 mg/kg/day), and (3) a CIA group was fed a 0.5% ALA diet (average ALA intake of 800 mg/kg/day). The ALA-fed mice showed a decreased incidence and severity of arthritis compared to the normal diet group. Radiographic findings revealed a dramatic decrease in bone destruction, and histological findings showed extensively suppressed pathological changes in the ALA-fed mice. The ALA-fed mice exhibited inhibited generation of tartrate resistant acid phosphatase (TRAP)-positive osteoclasts in vivo. Additionally, ALA-fed mice reduced production of various proinflammatory cytokines and the soluble receptor activator of NF-κB ligand (sRANKL) in the joint tissues and the sera. In conclusion, dietary supplementation with ALA attenuated inflammatory responses and bone destruction in CIA mice.