Thyroid autoantibodies

Analysis of the Application Value of Ultrasound Three-Dimensional Speckle Tracking Technology Combined with Thyroid Autoantibodies and Hormones in the Diagnosis and Treatment of Graves' Disease

Objective

The aim of the study is to evaluate the application value of three-dimensional speckle tracking imaging (3D-STI) and combined detection of thyroid autoantibodies and hormones in the diagnosis and treatment of Graves' disease.

Methods

A total of 60 patients with Graves' disease enrolled in our hospital from February 2020 to February 2021 were included in the experimental group, and 60 healthy patients after a physical examination during the same period were selected as the control group. No intervention was performed on the control group, and the experimental group received conventional Graves' disease treatment. The levels of thyroid autoantibodies and hormones in the two groups before and after the treatment were measured, and the 3D-STI was performed to compare the 3D-STI strain parameters of the research objects.

Results

A significantly higher level of thyroid autoantibodies in the experimental group than that in the control group before and after the treatment was found (P < 0.001), with a remarkable decline observed after the treatment (P < 0.001). The positive rate of thyroid autoantibodies in the experimental group before the treatment was significantly higher than that in the control group (P < 0.05). After the treatment, the positive rate of TRAb and TPOAb was higher than that of the control group (P < 0.05), and the positive rate of TPOAb was higher than before the treatment. The two groups showed no significant difference in the positive rate of TGAb (P > 0.05). Significant differences were observed in the thyroid hormone levels between the two groups and also between before and after the treatment (P < 0.001). The experimental group garnered significantly higher 3D-STI strain parameters than the control group before the treatment (P < 0.05); after the treatment, the hyperthyroidism of the patients was relieved with a decreased 3D-STI value, but it was still notably higher than the control group (P < 0.05). Remarkably higher positive rates of combined detection before and after the treatment in the experimental group than those in the control group were obtained (P < 0.05).

Conclusion

The combined detection of 3D-STI and thyroid autoantibodies and hormones ensures a better detection rate of Graves' disease and monitors the treatment effect of patients in real time, which provides a basis for clinical diagnosis and treatment and merits clinical promotion and application.

High cut-off value of a chimeric TSH receptor (Mc4)-based bioassay may improve prediction of relapse in Graves' disease for 12 months

There are scarce reports regarding a functional prognostic value of thyroid-stimulating autoantibody (TSAb) levels using a thyroid-stimulating hormone receptor chimera (Mc4) in Graves' disease (GD) in iodine sufficient area. The aim of this study was to investigate whether Mc4-TSAb can predict GD remission/relapse after antithyroid drug (ATD) treatment and to compare Mc4-TSAb with a binding assay using M22 monoclonal antibody (M22-TRAb) in GD patients. We retrospectively reviewed the results of M22-TRAb and Mc4-TSAb in GD patients treated with ATD for 12 months. GD patients who underwent ATD treatment for at least 12 months were included. We compared the predictive values of M22-TRAb and Mc4-TSAb for GD remission and relapse. Of the 92 patients, 60 (65.2%) achieved remission and 32 (34.8%) relapsed within 12 months. In receiver operating characteristic analysis, there were no significant differences in the area under the curves (AUCs) between Mc4-TSAb [AUC=0.79 (95% CI 0.69-0.89)] and M22-TRAb [AUC=0.69 (95% CI 0.58-0.81)]. The optimal predictive cut-off values of M22-TRAb and Mc4-TSAb were 2.23 IU/L and 230%, respectively. At a high Mc4-TSAb cut-off, the better specificity of 85.0% and positive predictive value (PPV) of 69.0% were shown compared with those at the best cut-off for M22-TRAb. In conclusion, a high cut-off for an Mc4 assay may improve the predictive value of relapse with superior specificity and PPV compared with M22-TRAb in treated GD.

Clinical review about TRAb assay's history

Commercial assays to measure thyroid stimulating hormone (TSH) receptor (TSHR) autoantibodies (TRAb) have been available for the serological diagnosis of autoimmune thyroid diseases (AITD) for several years. The widespread assessment of this parameter has identified Graves' disease (GD) as a common organ-specific autoimmune disease. Within the present article we aim to review immunobiological and epidemiological aspects as well as diagnostic methods available for the detection of TRAb. Over the last decade, TRAb detection in GD became more sensitive since TRAb assays were being largely improved by named research groups. Therefore, functional assay (fas) and diagnostic sensitivity of current TRAb assays will be discussed. Within the second part of this review we will focus on clinical applications of TRAb measurement for outcome prediction of GD as well as the importance of this method to distinguish GD from other AITD.

TSH receptor antibodies

The discovery of thyroid-stimulating autoantibodies by Adams and Purves 50 years ago was one of the most important observations in the history of thyroidology. Since that time, the thyroid-stimulating hormone receptor (TSHR) has been shown to be the antigen recognized by these autoantibodies (1974) and the receptor cloned (1989). More recently, different mouse monoclonal antibodies (MAbs) to the TSHR have been produced, culminating in 2002 in the preparation of mouse and hamster MAbs with strong thyroid-stimulating activity. Further, in 2003 a human MAb to the TSHR (M22) with the characteristics of patient thyroid-stimulating autoantibodies was described. M22 has been particularly useful in advancing our knowledge of the TSHR and TSHR autoimmunity, including the development of new assays for TSHR autoantibodies (2004) and determination of a high-resolution (2.55 A) crystal structure of the TSHR leucine-rich domain in combination with M22 (2007). The structure shows that M22 positions itself on the TSHR in an almost identical way to the native hormone TSH but the evolutionary forces that have resulted in production of a common autoantibody that mimics the actions of TSH so well are far from clear at this time. Very recently, a human MAb (5C9) with the characteristics of blocking-type patient serum TSHR autoantibodies has been isolated (2007). Studies on how 5C9 interacts with the TSHR at the molecular level are planned and should provide key insights as to the differences between TSHR autoantibodies with blocking and with stimulating activities. Also, 5C9 and similar MAbs have considerable potential as drugs to inhibit TSHR stimulation by autoantibodies. Further, now the M22-TSHR structure is known at the atomic level, rational design of specific low-molecular-weight inhibitors of the TSHR-TSHR autoantibody interaction is feasible.

Anti-thyroid-stimulating hormone receptor antibodies determined by second-generation assay

BACKGROUND

The aim of our study was to determine the frequency of anti-thyroid-stimulating hormone (TSH) receptor antibodies (TRAb) in Tunisian patients with Graves' disease (GD) and to compare the validity of TRAb to that of thyroperoxidase (TPO-Ab) and thyroglobulin antibodies (TG-Ab).

METHODS

ELISA was used to determine the frequency of TRAb, TPO-Ab and TG-Ab in sera of 190 patients with GD. Patients were divided into four groups: those with untreated active GD (group A, n=71), those receiving treatment with anti-thyroid drugs (group B, n=85), those in relapse (group C, n=15) and those in remission (group D, n=19). Sera of 100 healthy blood donors served as controls.

RESULTS

The sensitivity of TRAb for the diagnosis of GD (95.8%) was significantly higher than that of TPO-Ab (73.2%) and TG-Ab (42.2%) (p=0.0005 and p<10(-7), respectively). The positive rate for TRAb was lower in group B than in group A (70.6% and 95.8%, respectively; p=0.0001). The levels of TRAb were significantly higher in group A than in group B (mean 30.1 and 14.2 IU/L, respectively; p=0.006).

CONCLUSIONS

TRAb, but neither TPO-Ab nor TG-Ab, is valuable in the diagnosis and management of patients with GD.

Drug bioactivation, covalent binding to target proteins and toxicity relevance

A number of therapeutic drugs with different structures and mechanisms of action have been reported to undergo metabolic activation by Phase I or Phase II drug-metabolizing enzymes. The bioactivation gives rise to reactive metabolites/intermediates, which readily confer covalent binding to various target proteins by nucleophilic substitution and/or Schiff's base mechanism. These drugs include analgesics (e.g., acetaminophen), antibacterial agents (e.g., sulfonamides and macrolide antibiotics), anticancer drugs (e.g., irinotecan), antiepileptic drugs (e.g., carbamazepine), anti-HIV agents (e.g., ritonavir), antipsychotics (e.g., clozapine), cardiovascular drugs (e.g., procainamide and hydralazine), immunosupressants (e.g., cyclosporine A), inhalational anesthetics (e.g., halothane), nonsteroidal anti-inflammatory drugs (NSAIDSs) (e.g., diclofenac), and steroids and their receptor modulators (e.g., estrogens and tamoxifen). Some herbal and dietary constituents are also bioactivated to reactive metabolites capable of binding covalently and inactivating cytochrome P450s (CYPs). A number of important target proteins of drugs have been identified by mass spectrometric techniques and proteomic approaches. The covalent binding and formation of drug-protein adducts are generally considered to be related to drug toxicity, and selective protein covalent binding by drug metabolites may lead to selective organ toxicity. However, the mechanisms involved in the protein adduct-induced toxicity are largely undefined, although it has been suggested that drug-protein adducts may cause toxicity either through impairing physiological functions of the modified proteins or through immune-mediated mechanisms. In addition, mechanism-based inhibition of CYPs may result in toxic drug-drug interactions. The clinical consequences of drug bioactivation and covalent binding to proteins are unpredictable, depending on many factors that are associated with the administered drugs and patients. Further studies using proteomic and genomic approaches with high throughput capacity are needed to identify the protein targets of reactive drug metabolites, and to elucidate the structure-activity relationships of drug's covalent binding to proteins and their clinical outcomes.

Thyrotropin receptor antibodies: new insights into their actions and clinical relevance

The thyrotropin receptor (TSHR) is a G-protein-coupled receptor with a large ectodomain. TSH, acting via TSHR, regulates thyroid growth and thyroid hormone production and secretion. The TSHR undergoes complex post-translational processing involving dimerization, intramolecular cleavage, and shedding of its ectodomain, and each of these processes may influence the antigenicity of the TSHR. The TSHR is also the major autoantigen in Graves' disease, as well as a leading candidate autoantigen in both Graves' ophthalmopathy and pretibial myxedema. The naturally conformed TSHR is most effectively presented as an autoantigen to the immune system, causing the production of stimulating TSHR-Abs. There are also autoantibodies which block the TSHR from TSH action, and neutral TSHR-Abs which have no influence on TSH action. TSHR-Abs can be detected by competition assays of TSHR-Abs for labeled TSH, or monoclonal TSHR-Ab binding to solubilized TSHRs, or by bioassays using thyroid cells or mammalian cells expressing recombinant TSHRs.

Monoclonal antibodies to thyroid specific autoantigens

Monoclonal antibody (MAbs) is a powerful and essential tool to perform studies concerning antigens and antibodies at molecular level. MAbs to major thyroid specific autoantigens, thyroglobulin (Tg), thyroid peroxidase (TPO) and TSH receptor (TSHR), have been prepared and applied for a variety of investigations including the structure of antigens and antibodies, the expression of antigens, the epitopes of antibodies, the functional regions of antigens, mutated antigens in congenital diseases, and clinical applications to diagnosis of various thyroid diseases. Recently, sodium iodide symporter (NIS) was identified and became a potential thyroid autoantigen related to autoimmune thyroid disease, although few MAbs to NIS have been prepared. In this manuscript, I primarily focus on studies concerning MAbs to three major thyroid specific autoantigens, Tg, TPO and TSHR, and summarize studies using the mAbs.

Evaluation of a coated-tube assay for antithyrotropin receptor antibodies in patients with Graves' disease and other thyroid disorders

The detection of autoantibodies to the thyrotropin-receptor antibody (TRAb) is commonly used in clinical practice for the diagnostic assessment of Graves' disease (GD) and its differential diagnosis from toxic multinodular goiter (MNG) and autonomous adenoma. Additionally, TRAb assays can be useful during antithyroid drug treatment of GD to evaluate the risk of relapse and/or remission. The detection of TRAb was originally performed using a radioreceptor assay based on detergent-solubilized porcine thyroid membranes (TRAb). More recently new assays using purified porcine or recombinant human thyrotropin (TSH) receptor-coated plastic tubes (CT) have been developed (pCT-TRAb or hCT-TRAb). We have evaluated both assays (TRAb and pCTTRAb) in 300 individuals: healthy controls (n = 51); patients with GD before and after treatment (n = 200), patients with MNG (n = 29), and Hashimoto's thyroiditis [HT; n = 20]). All healthy controls and patients with HT had undetectable TRAb using both methods. Patients with active (not treated) GD had higher pCT-TRAb values (mean +/- standard deviation [SD], 58.2% +/- 20.3%, inhibition of TSH binding) compared to TRAb (41.2% +/- 15.4%, p < 0.01, Wilcoxon test). Results (as percent inhibition for both methods) had a positive and significant correlation (r = 0.68, p < 0.001). Moreover TRAb assay had a 97.3% sensitivity and 96.8% specificity; the pCT-TRAb sensitivity was 96.3% and specificity was 98.4% at a cutoff of 1.51 U/L. During treatment of GD, the TRAb method resulted in significantly lower (p < 0.05) values at 12, 24, and 30 months, while pCT-TRAb only exhibited significancy (compared to basal levels) at 30 months. The percent inhibition after 131I treatment of GD was significantly higher for pCT-TRAb (33.7 +/- 25.7) compared to TRAb (21.9 +/- 17.7, p < 0.01, Wilcoxon test). Only one patient with untreated MNG had a positive pCT-TRAb but negative TRAb value. Patients with MNG treated with 131I were divided into two groups: group 1 (only (131)I) or group 2 (hrTSH preceding (131)I). After MNG radioisotopic ablation, five patients had a positive pCT-TRAb and four had a positive TRAb (group 1) while in group 2, three patients had a positive pCT-TRAb and two had a positive TRAb assay. In conclusion, pCT-TRAb usually had higher percent inhibition values compared to TRAb in untreated GD, had a relatively lower decrease in percent inhibition values during treatment but exhibited a slightly increased sensitivity compared to TRAb. An advantage of the pCT-TRAb assay may be because of the coating system itself that might expose more receptor sites for the antibody.

Increased sensitivity of a new assay for anti-thyroglobulin antibody detection in patients with autoimmune thyroid disease

OBJECTIVES

To verify the cut-off values and to determine the clinical sensitivity of antithyroglobulin (TgAb) determinations using our routine RIA and the new electrochemiluminescent Elecsys assay.

DESIGN AND METHODS

We used the DYNOtest anti-Tgn manual RIA from BRAHMS and the new automated Elecsys electrochemiluminescent immunoassay from Roche Diagnostics. We analyzed 452 sera from the following subjects: 193 euthyroid controls, 163 with treated and untreated autoimmune thyroid diseases (AITD) (108 Graves' disease and 55 thyroiditis), 50 with differentiated thyroid carcinoma, 13 with nonautoimmune thyroid disease and 33 with type 1 diabetes mellitus.

RESULTS

As expected, using the proposed thresholds (BRAHMS 60 kIU/L, Elecsys 115 kIU/L) approximately 6% of the control subjects were positive for TgAb with both methods. In AITD patients, the sensitivity of TgAb determination was significantly higher with the Elecsys assay (51.5%) than with the BRAHMS assay (39.3%). This difference was not observed in the other patient groups.

CONCLUSION

The Elecsys assay can be preferred not only because it is automated and rapid, but also because of its better clinical performance in AITD patients.

Separation and detection methods for covalent drug–protein adducts

Covalent binding of reactive metabolites of drugs to proteins has been a predominant hypothesis for the mechanism of toxicity caused by numerous drugs. The development of efficient and sensitive analytical methods for the separation, identification, quantification of drug-protein adducts have important clinical and toxicological implications. In the last few decades, continuous progress in analytical methodology has been achieved with substantial increase in the number of new, more specific and more sensitive methods for drug-protein adducts. The methods used for drug-protein adduct studies include those for separation and for subsequent detection and identification. Various chromatographic (e.g., affinity chromatography, ion-exchange chromatography, and high-performance liquid chromatography) and electrophoretic techniques [e.g., sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional SDS-PAGE, and capillary electrophoresis], used alone or in combination, offer an opportunity to purify proteins adducted by reactive drug metabolites. Conventionally, mass spectrometric (MS), nuclear magnetic resonance, and immunological and radioisotope methods are used to detect and identify protein targets for reactive drug metabolites. However, these methods are labor-intensive, and have provided very limited sequence information on the target proteins adducted, and thus the identities of the protein targets are usually unknown. Moreover, the antibody-based methods are limited by the availability, quality, and specificity of antibodies to protein adducts, which greatly hindered the identification of specific protein targets of drugs and their clinical applications. Recently, the use of powerful MS technologies (e.g., matrix-assisted laser desorption/ionization time-of-flight) together with analytical proteomics have enabled one to separate, identify unknown protein adducts, and establish the sequence context of specific adducts by offering the opportunity to search for adducts in proteomes containing a large number of proteins with protein adducts and unmodified proteins. The present review highlights the separation and detection technologies for drug-protein adducts, with an emphasis on methodology, advantages and limitations to these techniques. Furthermore, a brief discussion of the application of these techniques to individual drugs and their target proteins will be outlined.

Fat-soluble vitamins in patients with acute renal failure

OBJECTIVE

Systematic investigations on the status of fat-soluble vitamins in patients with acute renal failure (ARF) are lacking and hence no recommendations for vitamin supply can be defined for these subjects. Thus we compared the status of fat-soluble vitamins, of transport molecules and some vitamin-dependent proteins in patients with ARF and healthy controls.

SETTING

Nephrology unit of a university hospital.

PATIENTS AND METHODS

Eight patients with ARF requiring hemodialysis therapy were investigated and 28 healthy volunteers served as controls. Plasma concentrations of retinol (vitamin A) and retinol-binding protein (RBP), 25-OH and 1,25-(OH)2 vitamin D3, of parathyroid hormone (PTH), of alpha-tocopherol (vitamin E) and of phylloquinone (vitamin K), osteocalcin and noncarboxylated osteocalcin, respectively, were measured and plasma lipoprotein fractions (as vitamin transport vehicle) were evaluated.

RESULTS

Vitamin A levels were decreased (p < 0.001), but RBP levels were normal in ARF patients. Vitamin D3 metabolites 25-OH and 1,25-(OH)2 vitamin D3 plasma levels were profoundly depressed, and PTH was elevated (p < 0.001). Vitamin E plasma concentration was reduced (p < 0.001) but this cannot be accounted for by decreased LDL cholesterol or triglyceride levels. In contrast, vitamin K plasma level was rather elevated in ARF patients with a broad range of individual values. Blood coagulation was normal but total and carboxylated osteocalcin were decreased. No correlation of vitamin K concentrations and any of the plasma lipoprotein fractions could be identified.

CONCLUSION

With the exception of vitamin K, profound deficiencies of fat-soluble vitamins develop in patients with ARF. Current recommendations for vitamin supplementation are inadequate and should be reevaluated for these patients.