Rodent models of osteoarthritis and rheumatoid arthritis are useful tools to study these disease processes. Adjuvant arthritis (AAR) is a model of polyarthritis widely used for preclinical testing of antiarthritis substances. We report the effect of two different doses of highly purified chondroitin sulfate (CS) pharmaceutical grade in the AAR animal model after oral administration.
AAR was induced by a single intradermal injection of heat-inactivated Mycobacterium butyricum in incomplete Freund's adjuvant. The experiments included healthy animals, untreated arthritic animals, arthritic animals having been administered 300 or 900 mg/kg of CS daily, 14 days before AAR induction until the end of the experiment (day 28), arthritic animals having been administered 300 or 900 mg/kg of CS daily, from day 1 until the end of the experiment.
CS was capable of significantly reducing the severity of arthritis along with oxidative stress, a consequence of chronic inflammatory processes occurring in AAR. The CS pre-treatment regimen was effective throughout the whole subacute phase, while treatment from day 1 proved effective only in the chronic period. The effects were confirmed by improved total antioxidant status and γ-glutamyltransferase activity. CS administered under a pre-treatment regimen was also able to reduce the production of pro-inflammatory cytokines, C-reactive protein in plasma, phagocytic activity and the intracellular oxidative burst of neutrophils.
CS proved to be effective in slowing down AAR development and in reducing disease markers, thus supporting its beneficial activity as a drug in humans.