CCR5 small interfering RNA ameliorated joint inflammation in rats with adjuvant-induced arthritis

Rheumatoid arthritis (RA) is a systemic inflammatory disease. C-C chemokine receptor type 5 (CCR5) is found in inflamed synovium of RA patients and is necessary for formation of RA. We aimed to check whether delivery of CCR5-specific small interfering RNA (siRNA) via electroporation suppresses local inflammation in arthritis rats. Vectors encoding siRNA that target CCR5 or negative control siRNA were constructed for gene silencing and the silencing effects of suppressing CCR5 expression in synovium examined by western blot. The vector with strongest effect was delivered into the knee joint of adjuvant-induced arthritis (AIA) rats by the in vivo electroporation method 7, 10, 13, and 16 days after immunization with Complete Freund's adjuvant. During an observation of 28 days, behavior, paw swelling, arthritis and histopathologic scoring were estimated. The expression level of CCR5 in synovium was evaluated by western blot and real-time PCR. Anti-CCR5 D1 siRNA was effectively inhibited CCR5 expression in vitro. Moreover, delivery of the siRNA into inflammatory joint also suppressed the expression of CCR5 in vivo and markedly suppressed paw swelling and inflammation. Local electroporation of anti-CCR5 siRNA into the left inflamed joints could achieve the silencing of CCR5 gene and alleviate local inflammation just in the knee joint injected with siRNA other than the opposite joint. Inhibition of CCR5 expression may provide a potential for treatment of RA.