间充质干细胞对大鼠实验性自身免疫性葡萄膜炎视网膜中白细胞介素17表达的影响

背景 研究显示Th17细胞是实验性自身免疫性葡萄膜炎(EAU)发病的重要致炎细胞群,而白细胞介素17( IL-17)作为Th17细胞的标志性因子参与了EAU的发生与发展.间充质干细胞(MSCs)作为一种免疫调节剂在多种自身免疫性疾病中对Th17具有抑制作用. 目的 研究MSCs对EAU的治疗作用以及对IL-17在大鼠视网膜表达的影响.方法 从10只SPF级Wistar大鼠股骨骨髓中分离、培养MSCs并进行传代,第3～5代细胞用于实验.54只SPF级6～8周龄Lewis大鼠按随机数字表法分为实验组48只和正常对照组6只.光感受器间维牛素A类结合蛋白(IRBP)与含有结核杆菌素HR37a的2.5 g/L弗氏完全佐剂(CFA)等体积混合后行实验组大鼠单后足垫皮下注射建立EAU动物模型,然后按照分层随机原则分为模型对照组和MSCs治疗组,每组24只大鼠.MSCs治疗组于造模的同时行1 ml MSCs尾静脉注射(5×106个／ml),连续注射3d,模型对照组以同法注射等体积PBS.注射后每日在裂隙灯显微镜下观察大鼠眼部炎症反应,并根据Caspi临床分级进行评分.分别于造模后9、12、15、20 d随机选取模型对照组和MSCs治疗组各6只大鼠制备视网膜切片,采用组织病理学方法观察大鼠视网膜形态学改变和炎症反应,参照Caspi组织学分级法进行评分.采用免疫组织化学染色法检测造模后9、12、15、20d大鼠视网膜中IL-17的表达.结果 培养的细胞呈梭形生长,漩涡状排列,经流式细胞术鉴定CD29、CD44表达阳性,CD45、CD34表达阴性.MSCs治疗组造模后9、12、15、20 d眼前节炎症反应评分均低于模型对照组(U=2.815,P=0.005;U=2.768,P=0.006;U=2.900,P=0.004；U=2.855,P=0.004),视网膜组织学检测炎症评分均低于模型对照组,差异均有统计学意义( U=2.345,P=0.019:U=2.559,P=0.011；U=2.166,P=0.030；U=2.373,P=0.018).免疫组织化学染色显示,MSCs治疗组造模后9、12、15、20d大鼠视网膜IL-17蛋白阳性表达的平均吸光度(A)值分别为26.47±5.68、77.78±9.65、47.02±6.68和26.59±5.94,明显低于模型对照组的45.34±4.63、105.95±10.74、64.11±9.76和37.02±6.51,差异均有统计学意义(t=6.305,P=0.000:t=4.799,P=0.001:t=3.540,P=0.005；t=2.900,P=0.016).结论 MSCs能减轻EAU的程度并抑制EAU的进展,降低了1L-17在眼组织中的表达.

Effect of mesenchymal stem cells on the expression of interleukin-17 in the retina of experimental autoimmune uveoretinitis

Background Studies determined that Thl7 cells are important inflammatory cell group in experimental autoimmune uveoretinitis （EAU）. Interleukin-17 （ IL-17 ） , as a marker of Thl7, is involved in the occurrence and development of EAU. Mesenchymal stem cells （MSCs） play an immunomodulatory role, mainly by inhibiting the expression of Thl7 in a variety of self-autoimmune disease. This is one of the current research focuses. Objective The present study was to investigate the therapeutic effect of MSCs in EAU and their impact on IL-17 expression in the retina. Methods MSCs were isolated from the bone marrow of the femurs from 10 SPF Wistar rats and cultured and passaged. The third to fifth generations of cells were used in this experiment. EAU models were induced in 48 6-8 week-old SPF Lewis rats by subcutaneous injection of interphotoreceptor retinoid binding protein （IRBP） R16 peptide emulsified in adjuvant. EAU rats were randomly assigned to the model control group and the MSCs group. MSCs suspension （5~106） of 1 ml was injected via the rat tall vein once a day for 3 consecutive days after immunization,and the same amount of PBS was injected in the model control group in the same manner. Six matched normal Lewis rats were used as the normal control group. The inflammatory response was clinically examined under the slit lamp biomicroscope daily,and the histopathological changes of the retina were examined by hematoxylin and eosin staining on days 9,12,15 and 20. The clinical and histopathological scoring was performed according to the Caspi criteria. Expression of the IL-17 protein in the retina was detected by immunohistoehemistry on 9,12,15 and 20 days following molding. The use of the animals complied with the Regulations for the Administration of Affairs Concerning Experimental Animals by Tianjin Municipality Science and Technology Commission. Results MSCs showed the fusiform in shape and vortex-like growth. Flow cytometry verified that presented the positive expression for CD29 and CD44 but absent expression for CD45 and CD34. The scores of the anterior segment were significantly lower （U=2.815,P=0.005;U=2.768,P=0.006;U=2.900,P=0.004;U=2.855,P=0.004）,and the retinal inflammation scores were lower in the MSCs group than the model control group at various time points （ U = 2. 345, P = 0. 019 ; U= 2. 559, P = 0. 011 ; U = 2. 166, P =0. 030 ; U = 2. 373, P = 0. 018 ）. Immnunochemistry showed that the expressions levels of the IL-17 protein （A value） in the rat retina were 26.47＋5.68,77.78± 9.65,47.02±6.68 and 26.59±5.94 in the MSCs group on days 9,12,15 and 20,and those in the control group were 45.34＋4.63,105.95＋ 10.74,64.11±9.76 and 37.02±6.51 ,showing a significant reduction （t= 6. 305,P=0. 000;t=4. 799,P=0. 001 ; t-3. 540,P=0. 005 ;t=2. 900,P=0. 016）. Conclusions MSCs can inhibit the aggravation of EAU and suppress the expression of IL-17 in ocular tissue.