Objective: To investigate the therapeutical effect of recombinant plasmid containing vasoactive intestinal peptide gene (pcDNA3.1+/VIP) on collagen-induced arthritis (CIA) in rats.
Methods: The experimental arthritis was induced by intradermal injection of bovine type II collagen emulsified in Freund's adjuvants in male SD rats. The rats then were given intra-articular injection with recombinant plasmid (pcDNA3.1+/VIP). The levels of serum TNF-alpha, IL-4 and IL-2 were detected by Avidin-Biotin Peroxdase Complex-enzyme-linked immunosorbent assay (ABC-ELISA) and the pathological changes in the joint of rats were observed.
Result: Histological examination showed massive inflammatory infiltration in the joint with destruction of bone and cartilage, while the severity of pathological changes in synovia of VIP-treated rats was markedly reduced. Compared with normal group, the serum TNF-alpha, IL-2 levels of CIA rats were significantly increased (P <0.05) and IL-4 level was decreased (P<0.05). Compared with control and pcDNA3.1+ -treated CIA rats, serum TNF-alpha and IL-2 levels of pcDNA3.1+/VIP-treated rats were decreased and IL-4 level was increased (P<0.05).
Conclusion: Recombinant plasmid containing vasoactive intestinal peptide gene (pcDNA3.1+/VIP) can reduce the clinical and histological severity of established CIA and it might be a promising candidate for treatment of rheumatoid arthritis.