The Effect Of Excessive Iodine Intake On The Expression Of IL-23、IL-17and IFN-γ In BABL/c Mice

ObjectiveTo observe the effect of excessive iodine intake for mice autoimmune thyroiditis and IL-17(Interleukin-17)、IL-23(Interleukin-23)、IFN-γ(Gamma interferon)mRNA expression changes in thyroid gland and spleen to further explore the pathogenesis that iodine overdose induced autoimmune thyroiditis.Methods7-8weeks old BALB/c mice wich are about20～25g and half male and female are selected and divided into4groups by body mass(every group has12and half male and female):control group (C):drink of deionized water; Thyroglobulin group (TG):drink deionized water, immunize with0.1mg Tg to each mouse by subcutaneously injection at8weeks old and enhance at11and15weeks old; iodine excess group (HI):receive0.05%NaI water; iodine excess+Thyroglobulin group (HI+TG):receive0.05%Sodium iodide (NaI) water, TG immunization is same as TG group. The four groups are fed with normal diet. After8weeks, kill the mice. Hematoxylin-eosin (HE) staining is employed to observe the histopathology of thyroid, chemiluminescence immuneassay(CIA) is used to observe the levels of thyroid hormone and SYBR Green real-time PCR(RT-PCR) is used to detect the levels of inflammation related genes (IL-17、IL-23、IFN-γ) in thyroid and spleen.ResultsCompared with the control group about the morphology changes of thyroid goiter is observed in the HI and HI+TG group that appear follicular expansion and glial retention,but thyroid follicula is consistent in the TG group.There are rare lymphocytic infiltration in the HI group, but single scattering lymphocytes infiltration in the TG group and local lymphocyte infiltration and destructed tissue in the TG+HI group.Among the4group, the content of Free triiodo thyronine (FT3)、Total thyroxine (TT4) and Free thyroxine (FT4) have significant differences between every two groups(F=12.54、4.00、10.62、P=0.00、0.03、0.00). RT-PCR show that in the thyroid the relative expression results of IL-23、IL-17and IFN-γ in the four group have big differences between every two groups.(F=9.0100、9.1920、4.7940, P=0.0000、0.0000、0.0060). The results are showed by using2-ΔCt.The expression results of IL-23(0.2576±0.1693、0.2620±0.1263) and IFN-γ (0.1850±0.1701、0.1448±0.0784)mRNA in TG and TG+HI group are significantly increased compared with the control group(0.1145±0.0732、0.0574±0.0329,P<0.05). The expression of IL-17(0.0174±0.0178) in TG+HI group is higher than the contro group (0.0006±0.003, P<0.05). In Spleen, IL-23、IL-17and IFN-γrelative expressions in the four group have big differences between every two groups.(F=9.0110、9.1370、3.5620,P=0.0000、0.0000、0.0220). In TG and TG+HI group,IL-17(0.0078±0.0066、0.0096±0.0100)、 IFN-γ(0.2193±0.0611、0.2228±0.2080) mRNA are higher than the control group (0.0018±0.0011、0.0761±0.0460,P<0.05).IL-23(0.0507±0.0426、0.1175±0.0831) mRNA in HI and TG+HI group is higher than the control group(0.0048±0.0052,P<0.05).ConclusionsLong-term excessive iodine intake leads to mice representing goiter and additionally aggravate TG induced autoimmune thyroid inflammation. IL-23、IL-17and IFN-γmRNA express more in the same time,wich suggest that IL-23、IL-17and IFN-γ play an important modulating role in the pathogenesis of autoimmune thyroiditis.