Study On The Roles And Mechanism Of NLRP3 Inflammasome In The Immunocyte Of Autoimmune Thyroiditis

Background:Autoimmune thyroiditis?AIT?,a common organ-specific autoimmune disorder,is the main cause of hypothyroidism.Genetic susceptibility,together with environmental factors,contributes to the breakdown of immune tolerance,but the specific molecular events are not clear yet.When activated by corresponding ligands,some members of the NLRs and ALRs receptor family?NLRP1,NLRP3,NLRC4,AIM2,Pyrin,etc.?recruit pro-caspase-1 or pro-caspase-11?non-classical pathway?through apoptotic associated Speck-like protein containing a CARD?ASC?and assemble them into macromolecule protein complexes to promote inflammation.This protein complex is known as Inflammatory Body?Inflammasomes?.It is highly expressed in rheumatoid arthritis,systemic lupus erythematosus,ulcerative colitis,multiple sclerosis and other autoimmune diseases,and participates in Activating of T cells and other processes.NLRP3 is the most widely studied inflammatory body.The role of NLRP3 inflammatory body in the pathogenesis of AIT has been confirmed by our team.Thus,iodine is one of the important environmental factors in the pathogenesis of AIT.The classical animal model of AIT,NOD.H-2h4 mice,has also confirmed that iodine is a necessary condition for inducing and aggravating AIT.However,whether iodine excess affects the secretion of inflammatory bodies in NLRP3 has not been reported.The aim of this study was to investigate the effects of iodine on NLRP3 inflammatory bodies and the differentiation of T helper cells in PBMC primary cells cultured from peripheral blood of AIT patients.To investigate the expression of sialic acid-binding immunoglobulin-like-lectin-1?Siglec-1?in the peripheral blood mononuclear cell?PBMC?of patients with autoimmune thyroiditis?AIT?and its relationship with AIT.To discuss about differentiation of immune cells with activated siglec-1 promoting the effects of inflammation after PBMC culture.Methods:Peripheral blood and serum were collected from 30 AIT patients with normal thyroid function and 30 age-and sex-matched healthy controls.PBMCs were cultured in vitro from AIT patients and normal control group.LPS or sodium iodide were used alone to stimulate PBMCs for 72 hours.The levels of NLRP3,ASC and caspase 1 in PBMC of each group were detected by rt-PCR and WB.The percentage of NLRP3 and Th1 cells?%?and Th17 cells?%?in CD14⁺monocytes of each group were detected by flow cytometry.The expression of sSiglec-1 in serum were detected by Elisa.The expression of Siglec-1 in PBMC was detected by rt-PCR,WB.The expression of Siglec-1 in CD14⁺monocytes and the proportion of Th1 and Th17 cells in each group were detected by flow cytometry.The PBMC in AIT or control was stimulated with NaI in the presence or absence of LPS for 72 hours.The expression of Siglec-1 in CD14⁺monocytes and the proportion of Th1 and Th17 cells were detected by flow cytometry.Results:After primary PBMC culture for 72 hours,the expression of NLRP3,ASC,caspase1 and caspase1 p20 in PBMC of normal subjects and AIT patients was up-regulated by sodium iodide at the concentration of 5 x 10^-5mol/L to 1 x 10^-2mmol/L?P<0.05?.NLRP3?%?in CD14⁺monocytes of both normal and AIT patients increased after stimulation with sodium iodide?P<0.05?.Th1?%?and Th17?%?in AIT patients increased?P<0.01?in a concentration-dependent manner.There was no significant difference between normal controls?P>0.05?.sSiglec-1 in serum,Siglec-1 mRNA and Siglec-1 protein in AIT patients'PBMC was higher than that in control group?P<0.01?.The expression of Siglec-1 in CD14⁺monocytes by flow cytometry and differentiation of Th1 and Th17 cells were significantly higher than that in control group?P<0.001?.The expression of Siglec-1 in control and AIT patients was up-regulated by 5 x 10^-55 mmol/L to 1 x 10^-2mmol/L stimulated with NaI in the presence or absence of LPS for 72 hours?P<0.001?,but the differentiation of Th1 and Th17 cells was up-regulated only in patients?P<0.01?,and in a dose-dependent manner.Conclusion:The expression of NLRP3 inflammasome and Siglec-1 in PBMC and monocytes may be a biomarker of AIT,and iodine may regulate the immune inflammatory response of AIT by activating NLRP3 inflammasome and Siglec-1 in AIT patients and affecting the differentiation of Th1 cells and Th17 cells.