Effect Of Caveolin-1 Expression On Autophagy Function In Thyroid Epithelial Cells Under Circumstance Of Inflammatory Cytokines

Background The pathogenesis of Hashimoto's thyroiditis(HT)is involved in various factors,including genetic susceptibility,environmental triggers,and immune disorders.Previous work from our laboratory has found that the autophagy activity in thyrocytes was sharply decreased in HT thyroid tissues compared with that of the healthy controls.Caveolin-1 is the main structure of flask-shaped plasma membrane invaginations known as Caveolae,which can participates in the occurrence and development of disease by regulation of autophagy activities.However,whether Caveolin-1 has an influence on the autophagy of thyrocytes remains largely unclear in HT disease.Objective To investigate the expression of inflammatory cytokines(IL-1?,IFN-?)and Caveolin-1 in thyroid tissues from HT patients,and observe the effects of IL-1? and IFN-? on Caveolin-1 and autophagy-related protein LC3B-II expression in thyroid epithelial cells,and explore the relationship between Caveolin-1 and autophagy activities.Methods 1.Specimens of thyroid tissues were obtained from eight simple goiter used as controls and eight patients with HT were enrolled.Immunohistochemistry staining(IHC)was used to detect the expression and location of IL-1?,IFN-? and Caveolin-1 in thyroid tissues from HT patients and controls.2.Thyroid epithelial cells line Nthy-ori 3-1 cells were treated with 2 ng/m L IL-1? and 10 ng/m L IFN-?,q RT-PCR was used to detect the level of Caveolin-1 m RNA.The change of Caveolin-1 was observed by immunofluorescence method and the expression of Caveolin-1 and LC3B-II were detected by Western blot analysis.3.Nthy-ori 3-1 cells were transfected with three different small interfering RNA sequences targeting human Caveolin-1(si Caveolin-1-439,si Caveolin-1-548,si Caveolin-1-710)or one negative control sequence(si Con).The successful knockdown of Caveolin-1 in Nthy-ori 3-1 cells was confirmed by Western blot analysis.4.The si Caveolin-1(si Caveolin-1-548)with the best efficiency of Caveolin-1 knockdown was applied into transfect Nthy-ori 3-1 cells,and the change of LC3B-II protein expression was detected by Western blot analysis.Results 1.HT thyroid tissues expressed higher levels of IL-1?,IFN-? and lower levels of Caveolin-1,especially where lymphocytes heavily infiltrated.IL-1? and IFN-? were not only detected in lymphocytes,but also were abundant in thyrocytes infiltrated by lymphocytes,and Caveolin-1 was mainly located in thyrocytes.2.Compared with the control group,after Nthy-ori 3-1 cells were treated with 2 ng/m L IL-1? and 10 ng/m L IFN-?,the expression of Caveolin-1 m RNA and protein was significantly decreased.In addition,the LC3B-II protein was also decreased by IL-1? and IFN-? treatment.3.The protein level of Caveolin-1 in the si Caveolin-1(si Caveolin-1-439,si Caveolin-1-548,si Caveolin-1-710)cells was lower than in the si Con group Nthy-ori 3-1 cells;in particular,si Caveolin-1-548 had the best efficiency in the Caveolin-1 knockdown system.4.After Nthy-ori 3-1 cells were transfected with si Caveolin-1-548,the expression of LC3B-II protein was significantly deceased with the knockdown of Caveolin-1.Conclusion Elevated levels of IL-1?,IFN-? and decreased levels of Caveolin-1 were expressed in HT thyroid tissues.Inflammatory cytokines(IL-1?/IFN-?)decreased the autophagy activity in the thyroid epithelial cells through inhibition of Caveolin-1 expression.