碘过量和甲状腺球蛋白免疫诱发NOD小鼠甲状腺炎的病变特征

Pathological characteristics of thyroiditis in NOD mice induced by iodine excess and thyrogiobulin immunization

目的观察碘过量和甲状腺球蛋白（b）免疫诱发甲状腺炎的病变特点，进一步了解碘过量在自身免疫性甲状腺炎发病中的作用机制。方法选用NOD小鼠，饮0．05％碘化钠（NaI）水和（或）Tg皮下免疫。观察甲状腺形态学改变和细胞凋亡情况；检测血清中TT4、TSH、甲状腺球蛋白抗体（TgAb）和甲状腺过氧化物酶抗体（TPOAb）水平；检测颈部淋巴结和脾脏淋巴细胞对Tg刺激的增殖反应和脾脏细胞培养上清中白细胞介素4（IL-4）和γ-干扰素（IFN-γ）水平；实时荧光定量PCR法检测甲状腺组织内IL-4、IFN-γ、趋化因子配体10（CXCL10）、细胞间黏附因子1（ICAM-1）mRNA的表达。结果碘过量组甲状腺滤泡扩张、胶质潴留；大量淋巴细胞浸润和结构破坏；滤泡上皮细胞凋亡数量增加（34．66±2．78vs5．11±0．62，P〈0．01）；总T4下降、TSH升高，无自身抗体产生；淋巴结和脾脏细胞对b刺激增殖实验呈阳性反应，脾脏细胞上清中IL4水平无升高，而IFN-γ升高[（1．272±0．049vs1．139±0．025）ng／L，P〈0．01]；甲状腺组织中除了IL-4外，IFN-γ、CXCL10、ICAM-1mRNA表达升高（均P〈0．01）。而Tg组甲状腺内有少量散在淋巴细胞浸润，产生了甲状腺自身抗体，脾脏细胞上清中IL-4水平升高[（18．508±0．113vs13．368±0．016）ng／L，P〈0．01]。碘和Tg联合作用炎症反应加重。结论碘过量所致的NOD小鼠甲状腺炎主要是以Th1反应为主的器官特异性自身免疫性疾病。碘过量联合Tg免疫对诱发实验性自身免疫性甲状腺炎具有协同作用。

Objective To observe the pathological characteristics of thyroiditis induced by iodine excess and thyroglobulin （Tg） immunization and to explore the mechanism of thyroiditis induced by iodine excess. Methods NOD mice were used for intaking 0. 05% NaI water and（or） Tg immunization. Morphologic change in thyroid and apoptosis were observed. The levels of serum TT4 , TSH, thyroglobulin antibody （ TgAb ） and thyroid peroxidase antibody （TPOAb） were measured. Responding to Tg,lymphocytic proliferation of lymph node and spleen, interleukin-4 （IL-4） and γ-interferon （IFN-γ）levels in culture medium of splenocytes were detected. Real-time PCR was used to detect mRNA expressions of IL-4, IFN-γ, chemokine ligand 10 （CXCL10） and intercellular adhesion molecular-1 （ICAM-1） in thyroid. Results Distended thyroid follicles,colloid accumulation, intense lymphocytic infiltration and disorganization were seen in thyroid of iodine excess group, along with increased apoptosis of thyroid cells （34.66 ± 2.78 vs 5.11 ±0.62 ,P〈0. 01 ）. The levels of TT4 were lowered while TSH raised ,but no production of thyroid-specific autoantibodies was revealed. Lymph node and spleen cells showed positive response under stimulation of Tg. The level of IFN-γ[ （ 1. 272±0. 049 vs 1.139±0.025 ） ng/L, P〈0. 01] was raised in culture medium of splenocytes but not IL- 4. The expression of IFN-γ, CXCL10 and ICAM-1 mRNA were increased in thyroid. But in Tg group, some lymphocytes were scattered in thyroid, autoantibodies emerged, and the level of IL-4 was increased in culture medium of splenocytes[ （ 18. 508±0. 113 vs 13. 368±0. 016） ng/L, P〈0.01 ]. Iodine excess combined with Tg enhanced these inflammatory reaction. Conclusion Iodine excess induced thyroiditis in NOD mice. The process seems to be Thl response dominant organ-specific autoimmune diseases. Iodine excess and Tg immunization play a synergistic role in inducing experimental autoimmune thyroiditis.