甲状腺相关眼病与Th1/Th2免疫平衡

背景 甲状腺相关眼病(GO)是自身免疫性疾病,目前其发病机制尚不清楚,近年来的研究发现Th1/Th2型免疫平衡反应的失调是导致GO的主要原因. 目的 采用脂质体包裹的人促甲状腺激素受体(hTSHR)胞外段基因重组质粒免疫同系雌性BALB/c小鼠以建立GO动物模型,研究关于在GO小鼠模型血清Th 1/Th2型免疫反应平衡状态,探讨GO的病理机制.方法 采用计算机数字随机分配法将同系6～8周龄雌性BALB/c小鼠32只分为重组质粒注射组、空白对照组、空质粒注射组和脂质体注射组.重组质粒注射组分别于实验的0、3、6周采用脂质体包裹的重组质粒pcDNA3.1 +/hTSHR289各30 μg行双胫前肌内注射,再于腹腔内注射40 μg以免疫小鼠,空质粒注射组和脂质体注射组分别采用pcDNA3.1+和脂质体以同样的方法进行免疫,空白对照组不做任何处理.分别于注射前及各次注射后第4天及第17周末处死小鼠行心脏采血,采用ELISA法检查各组小鼠血清中白细胞介素(IL)-2及IL-4质量浓度,计算IL-2/IL-4值.于初次免疫后17周末处死重组质粒注射组小鼠,取甲状腺及眼眶组织制作病理切片,采用苏木精-伊红染色法检测标本组织中炎性细胞浸润情况,对有炎性细胞浸润的标本进行免疫组织化学检测,计算B细胞特异标志物CD20阳性细胞(B)与T细胞特异标志物CD3ε阳性细胞(T)的比值,B∶T＞1.0者为Th2反应,相反者为Th1反应.结果 在第2次和第3次注射后,重组质粒注射组小鼠血清中IL-2质量浓度明显低于空白对照组、脂质体注射组、空质粒注射组,差异均有统计学意义(均P＜0.05),但组间小鼠血清IL-4质量浓度差异无统计学意义(P＞0.05);重组质粒注射组小鼠在第2次、第3次免疫后血清IL-2质量浓度明显低于免疫前及第1次免疫后,差异均有统计学意义(注射前:P=0.009、0.019;第1次注射后:P=0.002、0.004),而处死时小鼠血清IL-2质量浓度有所回升,明显高于第3次免疫后IL-2质量浓度(44.31±1.77) pg/ml与(42.43±2.29) pg/ml],差异有统计学意义(P=0.031).空白对照组、空质粒注射组、脂质体注射组、重组质粒注射组第2次、第3次注射后血清IL-4质量浓度及IL4/IL2值均明显高于注射前和第1次注射后,其处死时重组质粒注射组小鼠血清IL-4质量浓度明显高于第3次注射后,差异均有统计学意义(均P＜0.05).处死时重组质粒注射组苏木精-伊红染色有炎性细胞浸润的7只小鼠12个眼眶标本中4个眼眶B∶T值＞1.0. 结论 采用脂质体包裹的TSH受体胞外段基因重组质粒免疫同系雌性BALB/c小鼠可成功建立GO动物模型,重组质粒注射组小鼠在初次免疫后17周内以Th1型反应为主,小鼠第2次免疫后免疫平衡开始向Th2型转变.

The Th1/Th2-associated cytokines in the animal model of Graves ophthalmopathy

Background Graves opthalmopathy (GO) is an autoimmune disease,and its pathogenesis is not clear.Recent reports found that the imbalance of Th1/Th2 type immune response may be a main cause of GO.Objective This study was to establish an animal model of GO by immuning female BALB/c mice with recombinant plasmid of human thyroid-stimulating hormone receptor (hTSHR) A-subunit encapsulated with liposome induces.Methods Thirty-two female BALB/c mice aged 6-8 weeks were randomized to recombinant plasmid group,blank control group,empty plasmid group and liposome group.Recombinant plasmid pcDNA3.1 +/hTSHR289 containing 30 μg liposome was firstly injected into pretibial muscle and then into peritoneal cavity to construct the GO models at 0,3,6 weeks respectively in the recombinant plasmid group,and pcDNA3.1 + and liposome was used in the same way in the empty plasmid group and liposome group,respectively.No any intervene was performed in the blank control group.Heart blood of the mice was collected before injection and 4 days and 17 weeks after injection for the detection of serum interleukin (IL)-2,IL-4 and IL-2/IL4.The mice in the recombinant plasmid group were sacrificed at the end of 17 weeks of initial injection,and thyroids and orbital tissues were extracted for the regular histopathological examination.The expressions of CD20 for B cell specific markers (B) and CD3ε for T cell specific markers (T) were detected by immunochemistry and B ∶ T＞ 1.0 was Th2 response,and B ∶ T＜ 1.0 was Th1 response.Results Serum IL-2 levels in the recombinant plasmid group were significantly lower than those after injection of the 2nd time and 3rd time in the blank control group,empty plasmid group and liposome group (all at P＜0.05),but no intergroup difference was found in serum IL-4 level (P＞0.05).The serum IL-2 levels after injection of the 2nd and 3rd time were lower than those before injection and after injection of the 1st time in the recombinant plasmid group (before injection:P =0.009,0.019;after injection of the 1 st time:P =0.002,0.004),and the serum IL-2 level raised at the sacrifice of the mice,which was significantly higher than that after injection of the 3 rd time (44.31 ± 1.77] pg/ml vs.42.43±2.29]pg/ml) (P=0.031).Serum IL-4 levels and IL4/IL2 values after injection of the 2nd time and 3rd time were significantly higher than those before injection and after injetion of the 1 st time in the recombinant plasmid group,blank control group,empty plasmid group and liposome group,and in the sacrifice of the mice,the serum IL-4 level was higher than that after injection of the 3rd time in the recombinant plasmid group (all at P＜0.05).The B ∶ T values in 4 of 12 orbital tissue specimens of 7 mice that showed the inflammatory cell infiltration by regular histopathology were ＞ 1.0.Conclusions Immunization syngeneic BALB/c mice with liposome encapsulated thyrotropin receptor extracellular domain recombinant plasmid is an effective way to establish a GO animal model.The Th1 type response appears in initial 17 weeks following the first immunization,but the immune balance shifts toward a Th2 type after the second immunization.