Beta-endorphin prevents collagen induced arthritis by neuroimmuno-regulation pathway.

OBJECTIVE: To observe the effects and mechanisms of beta-endorphin (beta-END) preventing collagen induced arthritis (CIA) by neuroimmuno-regulating pathway.

METHODS: Female wistar (Ws) rats were used in this study. CIA was induced by Native bovine type II collagen emulsified with complete Freund's adjuvant (CFA). Beta-END was administered i.p. to CIA rats every other day from the 14th day (secondary immunization) to the 35th day after primary immunization. Clinical assessments were performed by two independent, blinded examiners every other day. Pathological and radiological observations were taken on the 35th day after the primary immunization. Tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), regulated upon activation, normal T-cell expressed and secreted (RANTES), inducible NO syntheses (iNOS), matrix metalloproteinase-2 (MMP-2) and MMP-9 mRNA expression of synovium tissues of CIA rats was estimated by quantitative RT-PCR. The frequency of spleen Th1 and Th2 cells were assessed by fluorescence activated cell sorter (FACS) assay.

RESULTS: Clinical manifestation of rats with CIA were significantly abrogated or ameliorated by treatment with beta-END. Beta-END treatment in vivo could down-regulate mRNA expression of several pro-inflammatory cytokines, chemokines and MMPs in CIA synovial, and polarize Th1/Th2 balance to Th2.

CONCLUSION: Beta-END alleviates CIA through both depressing Th1 responses and down-regulating proinflammatory and other rheumatic factors, suggesting beta-END is a promising anti-inflammatory and anti-rheumatic agent in treating CIA.