Expression Of Apoptosis-related Protein Livin, Hsp90α And Clusterin In Autoimmune Thyroid Diseases

Backgrounds and ObjectivesGraves disease and Hashimoto thyroiditis are the most common autoimmune thyroid diseases.Up to now,there are no exact pathogenesis illuminated.Recently evidence has emphasized the importance of apoptosis in the pathogenesis of autoimmune thyroid diseases.Livin,HSP90αand Clusterin protein are important anti-apoptotic factors.Livin protein can inhibit apoptosis through preventing Caspase pathway,activating TGF-βactivated kinase 1(TAK1)-dependent c-jun N-terminal kinase 1(JNK1) signal transduction pathway.HSP90αcan not only inhibit apoptosis through blocking the combination of procaspase-9 and apoptosis protease activating factor1,but also combine with mutant p53 and cause the accumulation of mutant p53 which can prolong the half-life of cells.HSP90αprotein may also play an important role in anti-apoptosis by blocking cell division.In addition,HSP90αhas important immune function.In the antigens processing and presentation,heat shock proteins can promote the assembly of antigens.Heat shock proteins themselves may be as the main antigens of different types of pathogens and the target proteins of the immune system in healthy person.Clusterin protein can protect cells from apoptosis and prevent antibody and complement-mediated cytolysis through binding with C5b-6,inhibiting the activation of C7,C8,C9 and formation of membrane attack complex. There is no report about the role of Livin,HSP90αin patients with Hashimoto thyroiditis and Graves disease up to now.We find no report about the role of Clusterin in patients with Hashimoto thyroiditis and Graves disease at home and only one about it abroad.To explore the role of Livin,HSP90α,Clusterin in the initiation and maintenance of Graves disease and Hashimoto thyroiditis,this study will investigate the expression of Livin,HSP90α,Clusterin protein in the thyroid tissues and analyze the correlation among them by S-P immunohistochemistry.Materials and Methods1.26 cases of Graves disease,15 cases of Hashimoto thyroiditis and 11 cases of normal thyroid tissues(adjacent to innocent thyroid adenoma) were obtained.The expression of Livin,HSP90α,Clusterin protein was detected by S-P immunohistochemical method.2.All specimens were evaluated by two pathologists who didn't acquire the clinical information of the patients.The average values were calculated.The cytoplasm,nucleus and(or) membrane of the cells were stained brown that was seen as positive staining of Livin,HSP90αand Clusterin protein.The percentage of positive cells and immunostaining intensity under high-power fields(400×) were classified into four groups:(-)The intensity of immunostaining was similar to background;(+) positive cells＜10%,weak staining;(++) 10%≤positive cells≤60%, moderate staining;(+++) positive cells＞60%,strong staining.3.Statistical analysis was carried out using SPSS12.0 statistical package.The comparison of counting data was analyzed byχ~2 test,Fisher's exact test and Spearman's rank correlation were used to assess the relation among Livin,HSP90αand Clusterin protein.The level of significant difference wasα=0.05.Results1.Livin protein and HSP90αprotein were mainly localized in the cytoplasm and nuclei of thyroid follicle epithelial cells.Clusterin protein was detectable in the membrane and cytoplasm of thyroid follicle epithelial cells.Livin,HSP90αand Clusterin protein were brown particles which had heterogeneous in Graves disease and Hashimoto thyroiditis.There was no expression of Livin,HSP90αand Clusterin protein in fibroblasts,vascular endothelial cells and infiltrating lymphocytes.Livin protein was mainly localized in the nuclei of cells in normal thyroid tissues and Graves disease,but in the cytoplasm of cells in Hashimoto thyroiditis.Expression of Livin protein in Hashimoto thyroiditis was enhanced in the areas where lymphocytes greatly infiltrated.The expression of Livin protein was higher in thyroid follicle epithelial cells which have more abundant cytoplasm or be in the intact thyroid follicles,and lower in thyroid follicle epithelial cells which have less cytoplasm or be in heavily damaged thyroid follicles.HSP90αprotein was mainly localized in the cytoplasm of thyroid follicle epithelial cells in normal thyroid tissues,Graves disease and Hashimoto thyroiditis.Between the lymphocytic infiltration areas and the areas far away from infiltrating lymphocytes,there was no significant difference in the expression of HSP90αprotein.Clusterin protein did not be expressed in normal thyroid tissues.In Graves disease and Hashimoto thyroiditis,Clusterin protein was mainly localized in the membrane and cytoplasm of thyroid follicle epithelial cells.In Hashimoto thyroiditis,the expression of Clusterin protein was higher in the side of follicular cavity than that of basement membrane.Clusterin protein was also expressed in follicular dendritic cells which were in the germinal center of lymphatic follicles that were formulated by infiltrating lymphocytes.2.In Graves disease and Hashimoto thyroiditis,Livin,HSP90αand Clusterin protein were significantly over-expressed compared to normal thyroid tissues (P＜0.05).There was no significant difference between the expression of Livin and HSP90αin Graves disease and Hashimoto thyroiditis(P＞0.05).The expression of Clusterin was significantly higher in Hashimoto thyroiditis than that in Graves disease (P＜0.05).3.In Hashimoto thyroiditis,there was a significant positive correlation between Livin and HSP90α(r=0.899,P＜0.05),but no significant correlation between Livin and Clusterin(r=0.202,P＞0.05),between HSP90αand Clusterin(r=0.374,P＞0.05).In Graves disease,although Livin did not correlated with HSP90α(r=0.211,P＞0.05) or Clusterin(r=0.126,P＞0.05),a significant positive correlation was found between HSP90αand Clusterin(r=0.617,P＜0.05)。Conclusions1.This study demonstrated that the expression of Livin,HSP90αand Clusterin protein was significantly higher in Hashimoto thyroiditis and Graves disease than that in normal thyroid tissues.Livin,HSP90αand Clusterin protein were mainly secreted by thyroid follicle epithelial cells.2.The highly expressed Livin,HSP90αand Clusterin protein might mainly inhibit the apoptosis of thyroid follicle epithelial cells in Graves disease and cause diffuse goiter.The over- expressed Livin,HSP90αand Clusterin protein in thyroid follicle epithelial cells of Hashimoto thyroiditis could protect thyroid tissues from apoptosis,but the expression of Clusterin protein in follicular dendritic cells which were in germinal center of lymphatic follicle might be one of the reasons that caused the damage and atrophy of the thyroid tissues.