Several studies demonstrated the pharmacological actions of carnosine as well as hyaluronic acid (HA) during joint inflammation. In that regard, the aim of this study was to investigate the protective effect of a new HA -Carnosine conjugate (FidHycarn) on the modulation of the inflammatory response in mice subjected to collagen-induced arthritis (CIA). CIA was induced by two intradermal injections of 100 μl of an emulsion of collagen (CII) and complete Freund's adjuvant (CFA) at the base of the tail on day 0 and 21. At 35 day post CIA induction, the animals were sacrificed.

CII injection caused erythema and edema in the hind paws, histological alterations with erosion of the joint cartilage as well as behavioral changes. Oral treatment with FidHycarn starting at the onset of arthritis (day 25) ameliorated the clinical signs, improved behavioral deficits as well as decreased histological and radiographic alterations. The degree of oxidative damage evaluated by inducible nitric oxide synthase (iNOS), nitrotyrosine, poly-ADP-ribose (PAR) expressions and malondialdehyde (MDA) levels, was also significantly reduced in Carnosine+HA association and FidHycarn treated mice. Moreover, the levels of proinflammatory cytokines and chemokines and cyclo-oxygenase COX-2 enzyme were also more significantly reduced by Carnosine+HA and FidHycarn compared to carnosine alone. However, interestingly, in some cases, the effects of FidHycarn were more important than Carnosine+HA association and not statistically different to methotrexate (MTX) used as positive control.

Thus, the conjugation of Carnosine with HA (FidHycarn) could represent an interesting therapeutic strategy to combat arthritis disorders.