| Objective:Exploring the possible role of vasoactive intestinal peptide in recombinant plasmid (pcDNA3.1+/VIP) in rheumatoid arthritis (RA) by detecting the level of TNF- α , IL-2 and IL-4 in serum and the pathological change in arthritis synovia of collagen-induced arthritis rat , in order to investigate the therapeutic effect of vasoactive intestinal peptide on CIA.Methods:1,Animal experiment Fourty-eight male SD rats weights 100g ± 5g were divided into 8 groups in random . The male SD rats were immunized intradermally with 100 μg of bovine CII emulsified in Freund' s complete adjuvant at their back and then boosted intradermaly with 100μg type II collagen in CFA at the base of their tail 10 days later. After successfully establishing CIA model, each CIA model received pcDNA3.1+/VIP (30 u g) by the intraarticular route in a total volume of 13 ul three times with an interval of 7 days. Rats were scored visually for theappearance of arthritis every 3 days in a blinded manner. Blood samples were collected at 50d for analysis the concentrations of serum cytokines(TNF- a x IL-2 and IL-4) by ELISA. Rats were killed by cervical dislocation and arthritis paws were fixed with 10% (w/v) liquor formaldehyde then detect the Histopathological change by immunohistochemical method.2> Histopathology Arthritic paws were fixed in 10% (w/v) liquor formaldehyde and decalcified in 15% EDTA, and embedded in paraffin. Sections (5 u m) were stained with hematoxylin-eosin. Histopathological changes were observed under microscope. Normal ratsserved as the control.3 -. Detection of Cytokine The serum TNF- a , IL-2 and IL-4 levels were assayed by ABC-ELISA according to the directions. Result:K Pathological change of sinovial tissue: The control joints of pcDNA3.1+ treated showed severe synovial inflammation with clear pannus attachment and erosions extending into the subchondral bone indicating destructive erosive disease pathlogy. Similar pathological changes were seen in the control arthritic joints. The arthritic joints of pcDNA3.1+/VIP treated rats showed lesser degree of both synovial inflammation and destructive pathology indicating a relatively normal joint architecture. After VIP treatment, histopathological analyses of joints showed complete remission of CIA-characteristic chronic inflammation of synovial tissue (infiltration of mononuclear cells into the joint cavity and synovial hyperplasia), pannus formation, cartilage destruction and bone erosion.2> Level of Cytokine: Compared with normal group , the level of TNF- a , IL-2 in serum of control group and pcDNA3.1+ treated group were significantly increased (P<0.05) and that of IL-4 was decreased (P<0.05). Compared with the control group and pcDNA3.1+ treated group, the expression of TNF- a and IL-2 in the serum of pcDNA3.1+/VIP group was decreased and IL-4 was increased(P<0.05). There is no difference was observed between the Hpofectin/pcDNA3.1+/VIP treated group and the pcDNA3.1+/VIP treated group.Conclusion1. Our observation confirmed that the vasoactive intestinal peptide in recombinant plasmid (pcDNA3.1+/VIP) is capable of reducing both the clinical and histologic severity of established CIA and it has been proposed as a promising candidate alternative treatment for rheumatoid arthritis.2. Vasoactive intestinal peptide in recombinant plasmid injected intraarticularly can significant inhibit the production of proinflammatory cytokine (expecially TNF- a ) . VIP promotes Th2 differentiation and subsequently leads to an increase in IL-4 production, inhibits Thl response subsequent IL-2 production.
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