Anti-inflammatory properties of natural ingredients used in combinations on adjuvant induced arthritis in rats

Background: Rheumatoid arthritis has seen a significant increase in both incidence and prevalence and its treatments show limited efficiency due to their undesirable effects on patient health. Therefore, major interests lie in the development of treatments with drugs derived from plants or other natural sources with little adverse effects as an alternative to current treatments. Hypothesis/Purpose: The present study evaluates the therapeutic effects of glucosamine against rheumatoid arthritis in combination with hyaluronic acid, resin extract of Boswellia serrata or a bark extract of Salix alba on an animal model. We suggest that combinations with plants could improve the attenuation of arthritis symptoms and articular inflammation. Study design: We used Freund’s complete adjuvant on rats as models of rheumatoid arthritis. Individuals were separated into eight experimental groups: a control group without arthritis, one with arthritis and without treatment, and six other groups receiving a daily therapeutic treatment from days 14 to 29. Methods: Hind-paw thickness and arthritis scores were measured at days 0, 3, 6 and 9 post-induction, and then every day from days 12 to 29 with a digital caliper and a score system respectively. At the end of the treatment, the mRNA content of three pro-inflammatory cytokines from cartilage was measured using real-time PCR. The total antioxidant activity was evaluated with an Antioxidant Assay Kit. Results: Treatments with Boswellia serrata and Salix alba (Glu+Hyal A+Bosw, Glu+Bosw+Sal, Glu+Bosw and Glu+Hyal A+Sal) saw significant reductions in hind-paw thickness and arthritis scores at the end of the experiment when compared to the untreated group. Expression of pro-inflammatory gene IL 17A was also reduced, but only the Glu+Hyal A+Sal combination significantly decreased the expression of IL-1β and TNF-α. The total antioxidant activity in blood plasma significantly increased in groups treated with plant extracts. Conclusion: The addition of Boswellia serrata and/or Salix alba attenuates clinical signs of rheumatoid arthritis in Freund’s complete adjuvant-induced arthritis in rats likely due to both their anti-inflammatory and antioxidant properties