Study On The Mechanism Of Inflammasome Activation Of Primary Thyrocytes From Autoimmune Thyroiditis Induced By Iodine

Objective: Autoimmune thyroiditis(AIT)is an organ-specific autoimmune disease caused by factors combined of genetic background,environmental factors and immune imbalance.At present,the damage of thyroid immune homeostasis induced by iodine excess has been recognized as an important factor in the pathogenesis of AIT,however,the process is not yet clear.Inflammasomes have been verified to play an important role in a variety of inflammatory and autoimmune diseases.Previous studies have confirmed that the expression of inflammasomes in the thyroid tissue of patients with AIT is significantly up-regulated and the inflammasomes mainly located in the thyroid follicular cells adjacent to the lymphocyte infiltration area.The study was designed to investigate the effects of iodine excess on the expression of inflammasomes in primary thyroid cells of AIT patients and normal controls in vitro,to investigate whether iodine excess affects the pathogenesis of AIT by regulating the expression of inflammasomes.Methods: In this study,we collected thyroid tissues from 15 patients with AIT and 15sex-and age-matched controls,and the thyroid primary cells were cultured in vitro.Thyroid cells were stimulated with 3 different concentrations of sodium iodide for 72 hours.The m RNA expressions of NLRP1,NLRP3,NLRRC4,AIM2,ASC,Caspase-1,IL-18 and IL-1β in thyroid cells were determined by RT-PCR,the levels of NLRP1,NLRP3,NLRRC4,AIM2,ASC,Caspase-1,GSDMD,TGN38 and Vimentin proteins in thyroid cells were measured by Western Blot,and the levels of IL-18 and IL-1β in supernatants were measured by ELISA,and compared with the quantitative analysis.Results: After being stimulated by 3 different concentrations of sodium iodide for 72 hours,(1)Compared with the blank control group,the m RNA expression levels of NLRP1,NLRP3,AIM2,ASC,Caspase-1 and IL-1β,IL-18 in thyroid cells of AIT group increased compared with that in control group after iodine stimulation of high concentration,the protein levels of NLRP1,NLRP3,NLRRC4,AIM2,ASC,Caspase-1increased significantly after iodine stimulation of medium concentration,the levels of IL-18 and IL-1β increased in culture supernatant,and the protein levels of GSDMD,TGN38 and Vimentin increased significantly after iodine stimulation of medium concentration.(2)Compared with the blank control group,the m RNA expression of NLRP1,NLRP3,NLRRC4,AIM2,ASC and Caspase-1 increased in the normal control group after iodine stimulation of high concentration,while the protein levels of NLRP1,NLRRC4,AIM2,ASC and Caspase-1 increased in the normal control group after iodine stimulation of low and medium concentration,the levels of IL-18 and IL-1 β in culture supernatant had no significantly difference,and the levels of GSDMD increased slightly,while the levels of TGN38 and Vimentin decreased slightly.(3)The m RNA expression levels and protein levesl of inflammasomes and their components in AIT group were higher than those in normal control group,especially after iodide stimulation.Conclusion: Iodine stimulation can significantly increase the expression levels of inflammasomes and their components in thyroid cells in AIT group,especially after iodine stimulation of high and medium concentrations.Iodine stimulation can also increase the expressions of inflammasomes and their components in thyroid cells in normal control group,but the increase was slightly and the trend was not obvious compared with thyroid cells in AIT group.