EAE模型中IL-17阻断MBP经鼻黏膜免疫诱导耐受的机制研究

Mechanism of IL-17 in breaking the tolerance induced by MBP via nasal mucosa in EAE model

目的探讨MBP68-86肽段经鼻黏膜诱导EAE模型免疫耐受中IL-17的作用机制。方法向4组Lewis大鼠鼻黏膜分别给与PBS、MBP、MBP+IL-17及MBP+IL-17^+腹腔注射Anti-IL-6,诱导免疫耐受给药5 d后,建立EAE动物模型。ELISA方法测定各组血清中细胞因子IFN-γ、IL-4、IL-6、IL-17和TGF-β的含量;评估EAE临床发病情况;脊髓切片分别做HE染色观察淋巴细胞浸润及分布情况,免疫组化方法检测脊髓中单位面积IL-17^+细胞数量;流式细胞仪检测淋巴结中Th17细胞和Treg细胞数量。结果IL-17组与MBP组细胞因子含量相比IFN-γ(P<0.05)、IL-4(P<0.01)、IL-6(P<0.01)、IL-17(P<0.001)、TGF-β(P<0.01)有显著差异,与PBS组无差异;IL-17组、PBS组与MBP组、Anti-IL-6组相比,免疫后出现体重减轻、尾瘫、后肢瘫痪等临床表现;脊髓切片中淋巴细胞浸润面积较大且细胞数量较多、IL-17^+细胞数显著增多;淋巴结中CD4^+IL-17^+T细胞百分率显著增多、CD4^+Foxp3^+T细胞显著减少。结论鼻黏膜给予IL-17可以打破MBP特异性免疫耐受的形成;并且IL-17是通过促进IL-6表达增加,使初始化的T细胞向Th17细胞分化增加,从而打破MBP鼻黏膜免疫耐受治疗EAE。

Objective To investigate the mechanism of IL-17 in breaking the tolerance induced by peptide MBP68-86 via nasal mucosa in EAE model.Four groups of lewis rats were given with PBS,MBP,MBP＋IL-17（via nasal mucosa）,and MBP＋IL-17（via nasal mucosa） with anti-IL-6（peritoneal injection）,respectively.After five days administration for immune tolerance,the model of EAE was established. ELISA was employed to detect the levels of cytokines IFN-Υ,IL-4,IL-6,IL-17,and TGF-β,which were significant difference between IL-17 group and MBP group（P0.05,P0.01,P0.01,P0.001,P0.01,respectively）,but no significance between IL-17 group and PBS group.As compared with MBP and MBP＋IL-17 with anti-IL-6 peritoneal injection group,body weight loss,tail paralysis,posterior limb paralysis were observed in MBP＋IL-17 and PBS group after immunization.HE staining showed the area of lymphocyte infiltration were large, and the quantity of IL-17~＋ cells was significantly increased in spinal cord section of MBP＋IL-17 and PBS group rats;Immunohistochemical method demonstrated that the percentage of CD4~＋IL-17~＋T cells increased significantly while CD4~＋Foxp3~＋T cells was noticeable reduced in lymph nodes of MBP＋IL-17 and PBS group rats.All the results mean that IL-17 administration via nasal mucosa can break the MBP-induced tolerance by increasing the expression of IL-6,which makes the increasing differentiation from naive T cell to Th17 cell.