碘过量和多聚肌苷酸-聚胞苷酸及甲状腺球蛋白诱发小鼠甲状腺炎对Toll样受体3表达的影响

目的 观察碘过量(high iodine,HI)和多聚肌苷酸-聚胞苷酸Polyinosinic-Polycytidylic acid,Poly (I:C),Poly]及甲状腺球蛋白(Thyroglobulin,TG)诱发小鼠甲状腺炎对Toll样受体3(Toll-like receptor 3,TLR3)表达的影响,探讨TLR3在自身免疫性甲状腺炎发病中的作用.方法 NOD(Non-obese diabetic)小鼠42只,体质量(20±3)g.按体质量将小鼠随机分为6组:对照组、HI组、Poly组、TG组、HI+TG组、HI+Poly组,每组7只.对照组:饮用去离子水,腹腔注射生理盐水0.1 ml,每天1次,连续1周,在处死小鼠前1周隔日1次,同样剂量生理盐水再注射3次;HI组:饮用0.05%的碘化钠去离子水,腹腔注射生理盐水(同对照组);Poly 组:饮用去离子水,腹腔注射0.1 ml Poly(1 g/L,按5 mg/kg体质量),每天1次,连续1周,处死前1周隔日1次,同剂量Poly再注射3次;TG组:饮去离子水,腹腔注射生理盐水(同对照组),皮下免疫猪TG 0.1 mg,在喂养第4、8周时分别再加强免疫1次,剂量减半;HI+Poly组:给药方法同HI组和Poly组;HI+TG组:给药方法同HI组和TG组.喂养8周后处死小鼠,取出甲状腺组织,冰冻切片、常规HE染色,光镜下观察小鼠甲状腺组织形态学变化:根据甲状腺组织炎细胞浸润数量及浸润范围、滤泡破坏范围等进行炎症程度分级;应用TLR3抗体对甲状腺切片进行免疫荧光染色,荧光显微镜下观察TLR3的表达,体视学分析甲状腺TLR3阳性细胞数密度变化.结果光镜下,Poly组甲状腺未见炎细胞浸润,HI组和TG组小鼠甲状腺都有不同程度的炎细胞浸润,HI+TG组和HI+Poly组甲状腺炎症细胞浸润和甲状腺滤泡破坏严重,炎症分级均在"++"以上.免疫荧光显示.HI组和Poly组的甲状腺滤泡上皮细胞可见到TLR3表达,在HI组和HI+Poly组炎症区域出现TLR3表达强阳性的炎症细胞.体视学分析甲状腺TLR3阳性细胞数密度,对照组、HI组、Poly组、TG组、HI+TG组、HI+Poly组组间比较差异有统计学意义(F=7.870,P<0.01);与对照组(0.062±0.025)mm2]比较,HI+Poly组(9.287±0.522)mm2]增加最为显著(P<0.01),而且HI+Poly组高于HI组(2.570±0.257)mm2]和Poly组(1.361±0.148)mm2,P均<0.01],HI+TG组(4.843±0.405)mm2]高于HI组和TG组(1.601±0.268)mm2,P均<0.01].结论 HI和TG免疫可诱发NOD鼠发生甲状腺炎,并刺激甲状腺滤泡上皮表达TLR3,Poly加重了HI诱发的NOD鼠甲状腺炎的病理变化过程;浸润的炎症细胞中亦有TLR3强阳性的细胞,提示TLR3途径参与了自身免疫性甲状腺炎的发病过程.

Effects of Iodine excess,polyinosinic-polycytidylic acid and thyroglobulin induced thyroiditis in mice on Toll-like receptor 3 expression

Objective To observe the effect of iodine excess(HI),polyinosinic-polycytidylic acidPoly(I:C),Poly]and thyroglobulin(TG)on the thyroid of mice by the expression of Toll-like receptor 3(TLR3)to reveal the functional role of TLR3 in autoimmune thyroiditis.Methods Forty-two non-obese diabetic mice,body weight (20±3)g,were divided into six groups:control group,HI group,Poly group,TG group,HI+TG group,HI+Poly group. Fed with deionized water and injected intraperitoneally with physiological saline 0.1 ml each day for a week, the mice in control group were injected with physiological saline every other day at the same dose for 1 week before they were sacrificed; HI group drank 0.05% NaI water and were injected intraperitoneally with physiological saline same as control group; Poly group drank deionized water and were injected intraperitoneally with poly 0.1 ml (1 g/L)each day of the week, then the mice were injected with Poly every other day at the same dose for 1 week before they were sacrificed; TG group drank deionized water and were injected intraperitoneally with physiological saline same as control group, immunized with 0.1 mg TG by subcutaneously injecting and the immunization was enhanced after they were fed half dose for 4 and 8 weeks separately. In HI + Poly group, the treatment was the same as HI group and Poly group; HI + TG group: the treatment was the same as HI group and TG group. Eight weeks later, mice were sacrificed and thyroids were taken to make frozen sections, Hematoxylin-Eosin (HE) staining was employed to observe the morphological change of the thyroids. The expression of TLR3 of thyroids was observed under fluorescence microscope after Immumofluorescence using TLR3 antibody and TR3-positive cells were analyzed in the thyroid density. Results HE staining showed thyroids of Poly group had no inflammation under microscope.There were different degrees of inflammatory cell infiltration in HI group and TG group. The inflammatory cell infiltration and the damage of follicular thyroid of HI + TG group and HI + Poly group were serious, and the degrees of inflammation were higher over "++". Thyroid follicular epithelial cell with TLR3 expression could be seen in Poly group and HI group, meanwhile, there were TLR3 strong positive inflammatory cells in HI group under fluorescent microscope. Using stereological analysis of TLR3-positive cell density in the thyroid, the difference between groups was statistically significant(F=7.870, P<0.01 ). TLR3-positive cell density in the thyroid of HI + Poly group was higher (9.287 ± 0.522)mm2] than control group (0.062 ± 0.025)mm2, P < 0.01] significantly, meanwhile, the density in HI + Poly group was higher than HI group (2.574 ± 0.257 )mm2] and Poly group (1.361 ± 0.148 )mm2, all P < 0.01]. The density in HI + TG group (4.843±0.405)mm2] was higher than HI group and TG group(1.601 ±0.268)mm2, all P < 0.01 )]. Conclusions Excessive iodine and thyroglobulin can induce thyroiditis, and stimulate the expression of TLR3 in the thyroid follicular epithelial, Poly aggravated thyroiditis induced by iodine excess in NOD mice; TLR3 positive inflammatory cells also appeared in inflammatory region, suggesting that TLR3 is involved in the pathogenesis of autoimmune thyroiditis