促甲状腺激素受体抗体检测的临床意义

50年前人们发现了促甲状腺激素受体抗体(TRAb),随着对促甲状腺激素受体(TSHR)结构和功能认识的不断更新,加之TSHR信号转导和与TRAb相互作用的逐步阐明,人们对TRAb及其临床应用的认识得到了进一步提高.TRAb的检测在Graves病(GD)及Graves眼病的诊断中有重要作用,并有效预测GD经抗甲状腺药物或放射性碘治疗后复发.其亦可应用于近期服碘的孕妇和乳母,因为甲状腺扫描对她们来说是禁忌的.另外,TRAb有助于胎儿、新生儿甲状腺功能亢进及其他类型的甲状腺毒症的诊断和鉴别诊断.目前,已有文献报道TRAb阳性的GD患者发生甲状腺肿瘤及不良预后之间的可能联系,但尚需更多的前瞻性研究来证实.     

促甲状腺激素受体抗体检测的临床意义

50年前人们发现了促甲状腺激素受体抗体(TRAb),随着对促甲状腺激素受体(TSHR)结构和功能认识的不断更新,加之TSHR信号转导和与TRAb相互作用的逐步阐明,人们对TRAb及其临床应用的认识得到了进一步提高.TRAb的检测在Graves病(GD)及Graves眼病的诊断中有重要作用,并有效预测GD经抗甲状腺药物或放射性碘治疗后复发.其亦可应用于近期服碘的孕妇和乳母,因为甲状腺扫描对她们来说是禁忌的.另外,TRAb有助于胎儿、新生儿甲状腺功能亢进及其他类型的甲状腺毒症的诊断和鉴别诊断.目前,已有文献报道TRAb阳性的GD患者发生甲状腺肿瘤及不良预后之间的可能联系,但尚需更多的前瞻性研究来证实.

Abstract：

It has been 50 years since the discovery of thyrotropin receptor autoantibody (TRAb). Advances in the knowledge of thyrotropin receptor ( TSHR) structure and function, combined with the elucidation of TSHR signaling and TSHR-autoantibody interaction have greatly facilitated our understanding of TRAb and their clinical applications. Measurement of TRAb activity plays an important role in the diagnosis of Graves' disease ( GD) and Graves' opthalmopathy. It has also been well recognized that TRAb is an effective predictor of GD relapse or remission after antithyroid drug and radioactive iodine treatment. TRAb test is of particular help in pregnant women and lactating mothers with recent iodine load, where radioactive iodine or technetium tests are contraindicated. In addition, it is useful in the diagnosis and differential diagnosis of fetal and neonatal hyperthyroidism as well as some rare forms of thyrotoxicosis in clinical practice. Accumulating evidence also indicates the possible correlation between thyroid cancer occurring in GD patients with positive TRAb and adverse outcomes. However, further innovation and standardization of TRAb tests are required to help pave the way for clinical applications.     

从Graves病动物模型看TSHR和TRAb

1996年Shimojo建立了Graves病(GD)动物模型后,开创了用表达促甲状腺激素受体(TSHR)的活体载体接种实验动物的新型GD动物模型。到目前为止,各种动物模型有其各自的优势和劣势,从不同模型中获得的信息远大于单一模型。对动物模型的研究证实,高度糖基化的TSHR的A亚单位启动或是增强了导致甲状腺功能亢进的免疫应答,TSHR氨基端在识别甲状腺刺激性抗体过程中具有重要作用。促甲状腺激素受体抗体(TRAb)的滴度水平和TSAb与TSH阻断性抗体(TBAb)的比例有关,这可能是抗体对免疫显性区的表位限制性所致。     

初发Graves病患者血清促甲状腺激素受体抗体水平的影响因素分析

目的分析初发Graves病(GD)患者体内促甲状腺激素受体抗体(TRAb)水平的影响因素。方法初发GD患者378例,采用酶联免疫吸附测定法检测患者血清TRAb,化学发光法检测血清甲状腺过氧化酶抗体(TPOAb)、甲状腺球蛋白抗体(TGAb)、游离甲状腺素(FT4)、游离三碘甲状腺原氨酸(FT3)和促甲状腺激素(TSH)。采用多元逐步回归分析法,以TRAb为应变量,以患者年龄、性别、病程、甲状腺质量、TGAb、TPOAb、是否突眼、FT3、FT4和TSH为自变量建立回归方程。结果甲状腺质量及合并Graves眼病(GO)与初发GD患者体内TRAb水平相关。结论甲状腺质量及合并GO是初发Graves病患者体内TRAb水平的影响因素。     

血清TRAb水平与Graves病患者131I治疗后早发甲减的关系

目的探讨血清促甲状腺激素受体抗体(TRAb)水平在Graves病(GD)患者131I治疗后早发甲状腺功能减低(甲减)发生中的作用,为临床随访监测提供依据。方法将123例GD患者按治疗前血清TRAb水平分为TRAb阳性组(TRAb>15 IU/mL)和TRAb阴性组(TRAb≤15 IU/mL),分别于131I治疗前及治疗后3、6、12个月测定血清游离三碘甲状腺原氨酸(FT3)、游离四碘甲状腺原氨酸(FT4)、促甲状腺激素(TSH)水平,并判定早发甲减发生情况。结果 TRAb阳性组和TRAb阴性组早发甲减率分别为54.72%(29/53)、31.43%(22/70),两组比较P<0.05。结论血清TRAb水平在GD患者131I治疗后早发甲减发生中起重要作用,临床可据此采取相关防治措施。     

促甲状腺激素受体在Graves眼病发病中的作用研究进展

Graves眼病 (GO)是一种器官特异性自身免疫性疾病 ,与Graves甲状腺功能亢进密切相关。在GO患者眼球后成纤维细胞上可以检测到促甲状腺激素受体 (TSHR)转录物及其片断 ,并有证据直接表明TSHR在眼球后表达。TSHR作为甲状腺—眼共同自身抗原 ,通过交叉免疫反应而引起球后的病变过程。TSHR基因突变与GO的关系 ,进一步说明TSHR独特的抗原决定簇在GO发病中的作用。     

Graves病的动物模型研究进展

总结了近年来有关Graves病(GD)动物模型的研究方法进展,主要有:(1)促甲状腺激素受体(TSHR)核酸免疫。(2)表达TSHR的成纤维细胞免疫和表达TSHR的M12细胞免疫。(3)表达TSHR的腺病毒免疫。(4)甲状腺刺激性抗体(TSAb)转基因动物模型。其中TSHR—腺病毒尤其是TSHR亚单位—腺病毒免疫小鼠的GD发生率高且较稳定,而TSAb转基因动物模型可进行传代是目前较有前景的方法。     

促甲状腺素受体抗体检测的临床意义

促甲状腺素受体抗体(TRAb)与多种自身免疫性甲状腺疾病的发病密切相关,是临床诊断这些疾病的重要指标.TRAb在功能上可分为甲状腺刺激性抗体(TSAb)和甲状腺刺激阻断性抗体(TSBAb),可与促甲状腺素受体分子上不同位点结合产生不同生物学效应.其中TSAb可引起Graves病(GD)患者甲状腺功能亢进和弥漫性甲状腺肿的发生,而TSBAb则可导致自身免疫性甲状腺功能减退症(甲减)患者甲减的发生.本文将对TRAb检测在GD鉴别诊断、辅助制定GD治疗方案、抗甲状腺药物疗效及预测复发、筛查自身免疫性甲减等方面的临床价值作一全面综述.     

促甲状腺激素的甲状腺外作用

近年来研究证明,促甲状腺激素受体(TSHR)存在于大脑、睾丸、肾脏、心肌、骨骼、胸腺、淋巴细胞、脂肪组织、纤维母细胞和肝细胞等多种甲状腺外组织和细胞上.促甲状腺激素(TSH)可能通过TSHR介导发挥着广泛的、非传统认识的功能作用.现主要列举了TSH在脂肪组织、骨骼和肝脏中的一些重要作用.     

TSHR胞外区中间段在BALB/c小鼠体内的免疫原性研究

目的观察促甲状腺激素受体（TSHR）胞外区中间段（TSHRm）的免疫调节作用，探讨TSHR分子结构与功能的关系。方法将血蓝蛋白与原核表达的人TS／HRm融合蛋白耦联，间隔15d注入BALB／c小鼠腹腔内共5次，对照组注射生理盐水；检测动物血清T4、促甲状腺激素受体抗体（TRAb）、促甲状腺激素受体刺激抗体（TSAb）、促甲状腺激素受体阻滞抗体（TBAb）水平及甲状腺组织病理变化。结果对照组动物T4水平升高后下降，TRAb水平较实验前升高，TSAb、TBAb无显著变化。实验组动物T4总体水平一直保持升高趋势；免疫30d时血清TRAb水平显著升高（P〈0．001），TSAb、TBAb水平变化表现为先升后降。甲状腺组织的病理变化为甲状腺上皮细胞增生和淋巴细胞浸润。结论 人TSHRm融合蛋白可刺激小鼠产生TRAb、TSAb和TBAb，其对动物机体的影响反映了TSAb和TBAb综合作用的结果，表明TSHRm可能具有TSAb及TBAb两种抗原表位。     

Measurement of thyroid blood flow area is useful for diagnosing the cause of thyrotoxicosis.

We have utilized color Doppler ultrasonography (CDU) to evaluate the thyroid blood flow area (TBFA) quantitatively, and we propose criteria to differentiate Graves' disease (GD) and destruction-induced thyrotoxicosis (DT) in patients with thyrotoxicosis. We studied 32 patients with diffuse toxic goiter, 21 with GD in the euthyroid state, 12 with chronic thyroiditis in the euthyroid state, and 31 normal individuals. TBFA was calculated as (thyroid blood flow area/thyroid area) x 100%. CDU showed high sensitivity (84%) and specificity (90%) in distinguishing GD from DT when TBFA was between 7.7% and 8.8%. Using CDU to diagnose GD in cases with TBFA >or=8% or positive serum anti-thyrotropin receptor antibody (TRAb), the sensitivity was 95% and the specificity was 90%, which are similar results to those obtained when GD was diagnosed by radioactive iodine uptake (sensitivity 100%, specificity 90%). Therefore, CDU is a more useful and economical method of distinguishing GD patients with TBFA of 8% or above from DT than measurement of TRAb or radioactive iodine uptake.     

Techniques to quantify TSH receptor antibodies

The presence of antibodies to TSH receptor (TSHR) is the hallmark of Graves disease (GD). These antibodies mimic the action of TSH, resulting in TSHR stimulation and hyperthyroidism, and have been associated with GD-associated extrathyroidal manifestations. TSH binding inhibition assays and bioassays for measurement of TSHR antibody levels have been used for clinical and research purposes. In the former, inhibition of TSH binding to purified or recombinant TSHR by a patient's immunoglobulins is measured by radioactive or chemiluminescent techniques. In the latter, cyclic AMP production is measured by use of radioimmunoassays or chemiluminescent methods in cells natively or artificially expressing TSHR. In this Review, the different techniques used for the detection of antibodies to TSHR are discussed, together with the clinical applications of antibody measurement, including diagnosis of GD and Graves ophthalmopathy. Prediction of relapse after medical treatment and the clinical course of Graves ophthalmopathy are also addressed.     

Thyrotropin receptor autoantibodies in Graves' disease.

Clinical thyrotoxicosis in Graves' disease patients is caused by thyrotropin receptor (TSHR)-stimulating autoantibodies. The molecular mechanisms of TSHR post-translational modification, TSHR signaling and TSHR-autoantibody interaction are still debatable, and the precise interaction of stimulating and blocking autoantibodies with TSHR is unclear. Recent TSHR epitope studies indicate that binding sites for stimulating and blocking autoantibodies are close together, not on distinct or distant parts of the molecule. Furthermore, new methods to detect TSHR autoantibodies and their clinical use are addressed. Highly sensitive TSHR autoantibody assays are widely available and cost efficient, and their routine clinical use might help in the differential diagnosis of hyperthyroidism and disease outcome prediction in patients with high levels of TSHR autoantibodies.     

Selective binding of thyrotropin receptor autoantibodies to recombinant extracellular domain of thyrotropin/lutropin-chorionic gonadotropin receptor chimeric proteins.

The extracellular domain of the glycosylated human thyrotropin receptor (ET-gp) contains epitopes that can adsorb pathogenic antibodies from sera of patients with Graves' disease (GD). In an attempt to define the regions within the ETSHR with which autoantibodies interact, we expressed extracellular domains of eight thyrotropin receptor/chorionic gonadotropin receptor (TSHR/LH-CGR) chimeric proteins in insect cells. The levels of expression were high and chimeric proteins were glycosylated. Chimeric proteins designated as EMc2+4 and EMc2+3+4, in which amino acids (aa) 90-165 and 261-370, and aa 90-370, respectively, of TSHR were replaced with corresponding aa of LH-CGR, partially reversed the thyrotropin binding inhibitory immunoglobulin (TBII) activity of experimental anti-TSHR antisera (anti-ET-gp). The other six chimeras almost completely reversed the TBII activity of these anti-ET-GP antisera. Next, we tested the ability of these chimeric proteins to reverse the TBII activity of GD patients' sera. Similar to our earlier study, ET-gp protein reversed the TBII activity of all eight GD patients' sera tested. Chimera EMc2, in which aa 90-165 of TSHR has been replaced with corresponding aa of LH-CGR, and EMc2+4 partially reversed the TBII activity of only three of the eight GD patients' sera. However, the other six chimeric proteins failed to neutralize the TBII activity of any of GD patients' sera. These data showed the following: (1) There is considerable heterogeneity amongst autoantibodies in GD patients' sera, (2) The TBII activity of some, but not others, is dependent on aa 90-165 and 261-370, and (3) Most Graves' sera, with TBII activity, failed to react with chimeric proteins in which either N-terminal or C-terminal regions of the extra cellular domain of the TSHR were replaced with corresponding regions of LH-CGR. These results suggest that the TBII activity of GD patients' sera is dependent on conformational epitopes and replacement of certain regions of TSHR with homologous regions of LH-CGR results in sufficient alteration in the conformation of the protein leading to loss of reactivity.     

Use of the 2nd generation TRAK human assay did not improve prediction of relapse after antithyroid medical therapy of Graves' disease

OBJECTIVE: Antithyroid drug treatment (ATD) is used world-wide in the treatment of thyrotoxicosis in patients with Graves' disease (GD). The main problem is a relapse rate of 30 to 50% within 2 years after the treatment has stopped. The measurement of thyrotropin receptor antibodies (TRAb) in serum has been used to confirm the diagnosis of GD in selected patients with a diagnostic specificity of 70 to 90%. However, in predicting the recurrence of thyrotoxicosis after discontinuing ATD it has been of little value. The aim of this study was to evaluate the ability of TRAb measured by the more sensitive recombinant human TSH receptor method to predict risk of recurrence of GD after discontinuing ATD. MATERIALS, PATIENTS AND METHODS: One hundred and twenty nine patients with newly diagnosed GD were included. Of these, 58 had relapse of hyperthyroidism in a follow-up of at least 11 months (median 18 months, range 11-49) after discontinuing ATD. In 122 Graves' patients TRAb were measured at the time of diagnosis and in all patients when discontinuing ATD by a competitive radioreceptor assay using recombinant human TSH receptors (TRAK human assay). RESULTS: We found an increased diagnostic specificity (99%) compared with the old TRAK porcine assay. The predictive values of a positive and negative test in relation to the prediction of a relapse of GD were found to be only 55% and 62% respectively when using a cut-off level of 1.5 IU/l, and the predictive value of a positive test decreased to 49% and of a negative test to 60% at a lower cut-off limit (1 IU/l). CONCLUSION: Our study confirms that the new TRAK human assay had a superior diagnostic sensitivity in comparison with the old TRAK porcine assay. Despite the higher diagnostic sensitivity of the TRAK human method, we could not find any improvement of predictive values for relapse of hyperthyroidism in the measurement of TRAb at the end of ATD.     

人促甲状腺激素受体的表达及其抗体的检测

人促甲状腺激素受体(TSHR)是自身免疫性甲状腺疾病(AITD)的一个重要抗原,TSHR抗体(TRAb)的检测对AITD的鉴别诊断及评价预后非常重要。目前TRAb的检测方法主要有两种,即放射受体分析法和生物分析法。两种方法均需要足够量的高纯度、高活性的TSHR蛋白,分子生物学的发展使重组TSHR的产量和活性大为提高,报告基因的引入可以区别甲状腺刺激性抗体和甲状腺阻滞性抗体。     

Measuring TSH receptor antibody to influence treatment choices in Graves’ disease

TSH receptor antibody (TRAb) plays a key role in the pathogenesis of Graves’ disease (GD), and its levels correlate with the clinical course. The second‐ and third‐generation TRAb assays have >95% sensitivity and specificity for the diagnosis of GD and have improved the utility of TRAb to predict relapse. TRAb levels decline with antithyroid drug (ATD) therapy and after thyroidectomy. Its level increases for a year following radioactive iodine (RAI) therapy, with a gradual fall thereafter. TRAb level >12 IU/l at diagnosis of GD is associated with 60% risk of relapse at 2 years and 84% at 4 years. The prediction of risk of relapse improves further to >90% with TRAb >7·5 IU/l at 12 months or >3·85 IU/l at cessation of ATD therapy. TRAb tests are not expensive, and hence, TRAb measurements at presentation, after 12 months and/or 18 months (at cessation) of ATD therapy, could potentially guide treatment choices in GD. Elevated TRAb favours definitive treatment in the form of RAI or thyroidectomy, depending on the presence or absence of moderate‐to‐severe Graves’ ophthalmopathy (GO) and the ability to comply with radiation protection requirements. Use of ATDs in early pregnancy is associated with increased risk of congenital anomalies; early ablative treatment (RAI/surgery) should be considered in women of childbearing age at higher risk of relapse of GD. TRAb ≥5 IU/l in pregnant women with current or previously treated GD is associated with increased risk of foetal and neonatal thyrotoxicosis, and hence needs close monitoring. TRAb levels parallel the course of GO, and elevated TRAb is an indication for steroid prophylaxis to prevent progression of GO with RAI therapy.