The Characteristics And Clinical Significance Of Serum TRAb IgG Subtype In Patients With Thyroid Associated Ophthalmopathy

BackgroundThyroid-associated ophthalmopathy?TAO?is an organ-specific and chronic autoimmune disease,the pathogenesis of which is still not completely clear,and it is currently thought to be related to susceptibility genes,environment,autoimmune imbalance,smoking and other factors.Numerous studies have shown that thyroid stimulating hormone receptor?TSHR?,as a common antigen existing in thyroid tissues and posterior ocular tissues,is involved in the occurrence and development of TAO.Its specific antibody thyroid stimulating receptor antibody?TRAb?belongs to IgG antibody,which can be divided into four subtypes:IgG1,IgG2,IgG3 and IgG4according to the structure of heavy chain and hinge area.With the assistance of different kinds of Th lymphocytes,antibodies can be converted to different subtypes.At different stages of TAO,there is an imbalance in the proportion of Th lymphocytes.In the active stage of the disease,orbital tissues are mainly infiltrated by Th1 lymphocytes and cytokines secreted by Th1 lymphocytes,mediating cellular immunity and participating in inflammatory reactions.Timely treatment with glucocorticoid and immunosuppressive agents can effectively inhibit inflammatory reactions and alleviate clinical symptoms such as tissue hyperemia,edema,photophobia and tears.During the stationary stage of disease,the orbital tissues were mainly infiltrated by Th2 lymphocytes and cytokines secreted by them,mediating humoral immunity,at this point is given priority to with tissue remodeling and chronic fibrosis,If the application of glucocorticoid shock therapy blindly,not only the patients can not get obvious relief of ocular symptoms,but also bear unnecessary hormone side effects.Therefore,accurate assessment of the inflammatory state of patients'eyes is of great significance in guiding clinical decisions.Currently,clinical activity score?CAS?is often used in clinical practice to divide TAO into active stage and resting stage.Higher score indicates more severe inflammation.Although simple and easy to operate,it is somewhat subjective,and patients often fail to get the best treatment due to inaccurate evaluation.Many studies have shown changes in the level of the IgG subtype in autoimmune diseases,but current studies on the distribution characteristics of the serum TRAb IgG subtype in TAO are very limited,and most studies are limited to outdated detection methods,and the conclusions are inconsistent.Therefore,this study constructed an ELISA system to detect the serum TRAb IgG subtype,and explored the distribution characteristics and clinical significance of the TRAb IgG subtype at different stages of TAO.ObjectiveTo explore the distribution characteristics of serum TRAb IgG subtypes in TAO patients at different stages,and the value of serum TRAb IgG subtypes in predicting whether TAO enters the active phase.MethodsCollected in August 2018 to February 2019 in the first affiliated hospital of zhengzhou university endocrinology clinic of 43 patients with thyroid-associated ophthalmopathy?GO?,30 cases with Graves disease?GD?,19 cases with Hashimoto's thyroiditis?HT?for their general clinical data and fasting serum.At the same time,50healthy subjects were selected from the physical examination department as the normal control group?NC group?.CAS was performed on patients in the GO group by the same experienced clinician.The serum concentrations of free triiodothyrogenine?FT3?,free thyroxine?FT4?,thyrotropin?TSH?,anti-thyroid peroxidase antibody?TPOAb?,anti-thyroglobulin antibody?TgAb?and thyrotropin receptor antibody?TRAb?were determined by chemiluminescence.The optical density values of TRAb IgG and IgG subtypes in the serum of the subjects were detected by ELISA,and the corresponding binding rate in percentage was calculated.The positive rate of each subtype and the relative content of positive samples in each group were calculated.The relationship between CAS and TRAb IgG subtype and its clinical significance were discussed.Results1.General clinical data of each group were compared:there were no significant differences in age and gender among GD group,GO group,HT group and NC group?P>0.05?.There was no significant difference between the GO group and the GD group in the duration of hyperthyroidism and smoking rate?P>0.05?.There was no significant difference between CAS<3 and CAS?3 group in gender,age,course of hyperthyroidism,course of TAO and smoking rate?P>0.05?.2.Comparison of thyroid function and thyroid related antibodies among groups:there were statistically significant differences in FT₃ and TSH levels among groups?P<0.05?,while no significant differences in FT₄ levels?P>0.05?.The levels of TPOAb and TgAb in the HT group and GD group were higher than those in the NC group and the GO group,and the differences were statistically significant?P<0.05?.The levels of TRAb in the GO group and GD group were higher than those in the HT group and the NC group?P<0.05?.There was no significant difference in the levels of TRAb between the GO group and GD group?P>0.05?.There was no significant difference in TPOAb,TgAb and TRAb levels between CAS<3 and CAS?3 groups?P>0.05?.3.The correlation test between concentration of TRAb and TRAb IgG?B?:they were positively correlated,the goodness of fit R²=0.709,the linear regression equation?=19.43 X-3.044.4.Comparison of TRAb IgG and IgG subtype?B?in each group:IgG?B?and IgG1?B?in GO group,GD group and HT group were significantly higher than those in NC group?P<0.05?,and IgG?B?in GO group was significantly higher than that in HT group?P<0.05?.IgG2?B?and IgG4?B?in GD group and GO group were higher than NC group?P<0.05?,IgG2?B?and IgG4?B?in GD group were higher than HT group?P<0.05?,IgG4?B?in GO group was higher than HT group,and IgG2?B?and IgG4?B?in other groups were not significantly different.There was no significant difference in IgG3?B?between the groups?P>0.05?.The GO group was further divided into CAS<3 points and CAS?3 points for comparison.IgG1?B?in CAS?3group was significantly higher than that in CAS<3 group,and IgG4?B?in CAS?3group was significantly lower than that in CAS<3 group,with statistically significant differences?P<0.05?.There was no significant difference in IgG2?B?and IgG3?B?between the two groups?P>0.05?.5.Comparison of positive rates of TRAb IgG subtypes in each group:the normal upper limit values of TRAb IgG subtypes?B?were 0.191,0.095,0.091 and 0.115,respectively.The positive rates of IgG1 and IgG4 in the GD group and the GO group were higher than those in the HT group,and the differences were statistically significant?P<0.05?.There was no significant difference in the positive rates of IgG2 and IgG3 between the groups?P>0.05?.The GO group was further divided into CAS<3 points and CAS?3 points for comparison.The positive rate of IgG1 in group CAS?3 was higher than that in group CAS<3 points,and the difference was statistically significant?P<0.05?.There was no significant difference in the positive rates of IgG2,IgG3 and IgG4 between the two groups?P>0.05?.6.Comparison of TRAb IgG subtype relative content in each group of positive samples:there was no significant difference in TRAb IgG subtype relative content in each group of positive samples?P>0.05?.The relative content of IgG4 in CAS<3group was significantly higher than that in CAS?3 group,and the difference was statistically significant?P<0.05?.There was no significant difference in the relative content of IgG1 and IgG3?P>0.05?.7.Logistic regression analysis for multiple factors affecting TAO activity:FT₃,FT₄,TSH,TPOAb,TgAb,TRAb,IgG1?B?,IgG2?B?,IgG3?B?,IgG4?B?were used in forward stepwise method to establish a logistic regression equation?=6.190 IgG1?B?-16.390 IgG4?B?.8.The ROC curve analysis of[TRAb IgG1?B?×IgG2?B?]/[IgG3?B?×IgG4?B?]for predicting the active phase of TAO showed that AUC was 0.859?P<0.05?and95%confidence interval was?0.746,0.973?.When[TRAb IgG1?B?×IgG2?B?]/[IgG3?B?×IgG4?B?]was 4.29,the Jordan index was the largest.The sensitivity and specificity of predicting TAO entering the active phase were 81.8%and 81.0%respectively.9.Comparison between the GO smoking group and the non-smoking group:all smokers were male,and there were 29 females and 4 males among the non-smokers,with statistically significant difference in gender distribution?P<0.05?.TRAb IgG4?B?in the smoking group was higher than that in the non-smoking group,and the difference was statistically significant?P>0.05?.There was no significant difference between the two groups in age,course of hyperthyroidism,TAO course,FT₃,FT₄,TSH,TPOAb,TgAb,TRAb,TRAb IgG1?B?,IgG2?B?,IgG3?B?and CAS?P>0.05?.Conclusions1.Elevated levels of IgG1 in the patients with thyroid-associated ophthalmopathy indicate a tendency to active stage,while elevated levels of IgG4indicate a tendency to stationary stage.2.Elevated levels of IgG4 in smokers with thyroid-associated ophthalmopathy may be associated with the chronic stimulation of smog.3.[TRAb IgG1?B?×IgG2?B?]/[IgG3?B?×IgG4?B?]can be one of the indicators predicting the entry of TAO into the active phase.