辣椒素通过抑制自噬活性抑制实验性自身免疫性神经炎

Capsaicin inhibits experimental autoimmune neuritis in rats through inhibition of autophagy activity

目的观察辣椒素对大鼠实验性自身免疫性神经炎(EAN)的影响并探讨其机制。方法♂Lewis大鼠采用P2_(57-81)多肽与完全弗氏佐剂的混合液足底注射诱导EAN模型。在免疫后0.5 h,通过腹腔注射给予雷帕霉素(2.5 mg·kg^(-1)),免疫后1 h给予辣椒素(1 mg·kg^(-1)·d^(-1))灌胃,共15 d。每天观察大鼠发病情况,并进行神经系统体征临床评分和体质量测量,坐骨神经病理切片进行HE染色和劳克坚牢蓝染色,透射电镜观察坐骨神经的超微结构。采用ELISA法检测大鼠血清中肿瘤坏死因子-α(TNF-α)、干扰素γ(IFN-γ)、白介素^(-1)β(IL^(-1)β)、白介素-6(IL-6)水平;Western blot检测坐骨神经中自噬相关蛋白的表达。结果与EAN组比较,EAN+辣椒素组大鼠从免疫后d 7~16神经系统体征临床评分明显降低,体质量从免疫后d 3~16明显增加(P<0.05),髓鞘脱失现象明显减少,炎症细胞浸润数明显减少(P<0.05),血清中TNF-α、IFN-γ、IL^(-1)β、IL-6水平明显降低(P<0.05),大鼠坐骨神经轴突中自噬体数量明显减少(P<0.05),坐骨神经中Beclin^(-1)、LC3-Ⅱ蛋白的表达及LC3-Ⅱ/LC3-I的比值均明显下调,p62的表达明显上调(P<0.05)。雷帕霉素部分逆转了辣椒素的作用。结论辣椒素能抑制实验性自身免疫性神经炎,其机制与抑制细胞自噬活性有关。

Aim To observe the effect of capsaicin on the experimental autoimmune neuritis( EAN) in rats and explore the mechanism. Methods To induce EAN,male Lewis rats were immunized with peripheralnerve myelin sheath antigen( P2_(57-81)) peptide and complete Freund's adjuvant( CFA) mixed liquor. Rapamycin( RAPA,2. 5 mg·kg^(-1)) was administered by intraperitoneal injection 0. 5 h after immunization and capsaicin( 1 mg · kg^(-1)·d^(-1)) was administered by intragastric administration 1. 0 h after immunization for15 days. The incidence and clinical characteristics of EAN were observed. The clinical scores of neurological signs were completed and body weight was measured.Pathological morphology of sciatic nerve was observed by HE staining and Lauck fast blue staining. Ultrastructure of sciatic nerve was observed by transmission electron microscope. Levels of serum tumor necrosis factor alpha( TNF-α),interferon gamma( IFN-γ),interleukin 1β( IL^(-1)β) and interleukin-6( IL-6) were tested by enzyme linked immunosorbent assay( ELISA). Expressions of autophagy related protein were measured by Western blot. Results Compared with EAN group,the clinical scores of neurological signs significantly decreased from day 7 to day 16 of post-immunization( P < 0. 05),body weight significantly increased from day 3 to day 16 of post-immunization( P < 0. 05), demyelination obviously decreased,inflammatory cell infiltration number obviously decreased( P < 0. 05),the levels of TNF-α,IFN-γ, IL^(-1)β and IL-6 significantly decreased( P <0. 05),the number of autophagosome in axon of sciatic nerve significantly decreased( P < 0. 05),and expressions of Beclin^(-1) and LC3-Ⅱ and the ratio of LC3-Ⅱand LC3-Ⅰ were significantly down-regulated,and the expression of p62 was significantly up-regulated( P <0. 05) in EAN + capsaicin group. Rapamycin partially reversed the action of capsaicin. Conclusions Capsaicin inhibits EAN in rats,and the mechanism may be related with the inhibition of autophagy activity.