The Effect Of Rhu-TNFR-Fc On Adjuvant Arthritis In Rats And Expression Of TNF-α, HIF-1α, VEGF In Serum And Synovial

Objective: Rheumatoid Arthritis(RA) is a kind of chronic, progressivity, systemic and autoimmune disease with key features of arthrosynovitis, symmetric and destructive arthropathy. However, the cause of RA is still unclear. The center of formation and development of RA perhaps include: activation of many kinds of immunocytes, participation of cell factors and mediators of inflammation, production and development of pannus in synovial which promoted the destruction and joint remodeling of cartilage and bone, the final lead to the joint malformation, rigidity and functional incapacitation. A simplified view of TNF-alpha mediates the cytokine cascade that causes inflammation and joint destruction in RA and plays a central role in the sequence of cellular and molecular events underlying the inflammatory process of synovium. Now the main therapeutic tool is symptom modifying anti-rheumatic drugs. But patients often are difficult to insist on taking medicines in long-term because of side effect. However, Etanercept(rhu-TNFR-Fc), a biologic inflammation modulator, has been developed for therapeutic neutralization of TNF-alpha. In the clinical, Etanercept is indicated for the reduction of signs and symptoms of moderately to severely active RA in patients who have had an inadequate response to one or more DMARDs. However, internal reports on anti-angiogenic of RA therapy is unusual. The aim of this study is to evaluate effect of Etanercept on arthritis of adjuvant-induce-arthritis rat from many aspects: arthrocele, concentrations of TNF-αin blood and TNF-α, HIF-1αand VEGF in synovium, pathology, investigating mechanism in treating RA and assesing the value of clinical application.Methods: (1) The Wister rats were divided into five groups in random. GroupⅠwas normal group; GroupⅡwas model group; GroupⅢwas MTX group; GrsoupⅣwas Etanercept with 0.44mg/kg; GroupⅤwas Etanercept with 0.88mg/kg. Rats of groupⅡ,Ⅲ,Ⅳ,Ⅴwere given intradermal injection with the emulsion of complete Freund's adjuvant and heat-killed Mycobacterium tuberculosis into the base of the tail and induce AA model. (2) On the 12th day after induction, groupⅢwere given an intragastric administration with MTX (2.7mg/kg.w); groupⅣwere given subcutaneouly injection with Etanercept (0.44mg/kg.d); groupⅤwere given subcutaneouly injection with Etanercept (0.88mg/kg.d). (3) The foot volume was detected and arthritic index was measured per triduum. (4) The level of TNF-αin serum was measured by ELISA on the 28th day. (5) Immunohistochemistry was used to detect the expression of TNF-α,HIF-1αand VEGF in synovial tissues and intensity was analyzed by digital image analysis system. (6) Histopathology of synovium tissue was observed and evaluated using histopathology integral. (7) SPSS 13.0 statistical software was used to analyze data.Results: (1) In different time after induction, arthritis index (AI) of groupⅡwas significantly higher than that of groupⅠ( P<0.01), and reached the peak time from the 21th day to the 28th day. During the 18～27th days, AI of groupⅤwas significantly lower than that of groupⅡ(P<0.05), but similar with groupⅢand groupⅣ( P>0.05). (2) The foot volume: from 15th day to the 27th after induction, the foot volume of groupⅡwas significantly higher then that of groupⅠ( P<0.01), and reached the peak time during the 21～24th days. The foot volume of groupⅢ,ⅣandⅤwere significantly higher than that of groupⅠ( P<0.05) during the 18～27th days after induction. During the 21～24th days after induction, groupⅣwas significantly lower then groupⅡ(P<0.05), but similar on the 27th day. And during the 21～27th days, groupⅤwas significantly lower than that of groupⅡ(P<0.01). (3) Concentration of TNF-αin blood plasma: GroupⅠwas significantly lower than groupⅡ,ⅣandⅤ( P<0.05), but similar with groupⅢ(P>0.05). GroupⅢ,ⅣandⅤwas significantly lower than groupⅡ(P<0.01). GroupⅢwas significantly lower than groupⅣ, but similar with groupⅤ. (4) IOD of TNF-α, HIF-1αand VEGF and histopathological integration of synovium:①On the 28th day after induction, above-mentioned datas of groupⅡhigher than groupⅠand all of statistic differences were significant.②IOD of TNF-αin synovium: Both groupⅣandⅤwere significantly lower than groupⅡ(P<0.05). GroupⅤwas significantly lower than groupⅣ(P<0.05). GroupⅢwas significantly higher than groupⅣandⅤ, but similar with groupⅡ(P>0.05).③IOD of HIF-1αand VEGF in synovium: GroupⅢ,ⅣandⅤwere significantly lower than groupⅡ(P<0.05). GroupⅢwas similar with groupⅣ(P>0.05), but both of them were significantly higher than groupⅤ(P<0.05).④Histopathological integration of synovium: GroupⅢ,ⅣandⅤwere significantly lower than groupⅡ(P<0.05). GroupⅢwas significantly higher than groupⅤ(P<0.05), but groupⅢandⅤwere similar with groupⅣ(P>0.05). (5) Analyz of dependablity: There was significantly positive correlation between AI and foot volume. Significantly positive correlation between both TNF-αand HIF-1αand VEGF of synovium was shown. And the three cytokines not only in blood plasma but also in synovium were positive correlate with foot volume, histopathological integration of synovium.Conclusions: (1) Etanercept could significantly reduce inflammation, AI and foot volume of AA rats. (2) Etanercept could effective inhibit or delay the change of pathological in synovium of AA rats. And it might be controlled development of inflammation. (3) The dose dependent manner is seen efficacy of therapy to AA rats with Etanercept. Etanercept with high dose were better then MTX, but Etanercept with low dose were similar with MTX. (4) Etanercept could reduce the level of TNF-αin blood plasma of AA rats. (5) Etanercept could depress the expression of TNF-α, HIF-1αand VEGF in synobial membrane. (6) AI was significantly positive correlated with foot volume. They could reflect the swelling of joint, but the latter was better in precise, objective and economy. (7) The levels of TNF-αin blood plasma and the levels of TNF-α, HIF-1αand VEGF of synovium were obviously increased after induction and significantly positive correlated with foot volume and pathological integration of synovium. The results hint that these three cytokines educed important effect in pathological process of RA.