MICROSOMAL AND THYROGLOBULIN ANTIBODIES IN THYROID DISORDERS.
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ABSTRACT:
SUBMITTER: Dham SK
PROVIDER: S-EPMC5530228 | biostudies-other | 1995 Oct
REPOSITORIES: biostudies-other
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Project description:ObjectiveThyroid disease in women of reproductive age is mainly of autoimmune origin, and thyroid peroxidase antibodies (TPO-Ab) as well as thyroglobulin antibodies (Tg-Ab) are key markers. Adding to this, much focus in pregnancy is on euthyroid women who are thyroid antibody positive. Evidence to substantiate the cut-offs for the definition of thyroid autoantibody positivity in early pregnant women is warranted.MethodsStored serum samples from 14,030 Danish pregnant women were used for the measurement of TPO-Ab, Tg-Ab, TSH, and free thyroxine (ADVIA Centaur XPT, Siemens Healthineers). Among all women, a reference cohort of 10,905 individuals was identified for the establishment of antibody cut-offs. Percentile cut-offs for TPO-Ab and Tg-Ab were determined using regression on order statistics (the reference cohort). The established cut-offs were then applied (the full cohort), and frequencies of early pregnancy as well as later diagnosis of hypothyroidism were evaluated.ResultsThe highest established cut-offs (95th, 97.5th, and 99th percentiles) were 59, 68, and 81 U/mL for TPO-Ab and 33, 41, and 52 U/mL for Tg-Ab. When the cut-offs were applied in the full cohort, 11.0, 10.2, and 9.7% were TPO-Ab positive, whereas 13.3, 12.3, and 11.2% were Tg-Ab positive. Antibody-positive women (TPO-Ab and/or Tg-Ab) had higher median TSH and were more likely to have hypothyroidism in early pregnancy and to be diagnosed with hypothyroidism during follow-up.ConclusionsThis large study established and evaluated pregnancy-specific cut-offs for TPO-Ab and Tg-Ab. The findings are important regarding the classification of exposure in pregnancy and assessment of thyroid autoimmunity per se.
| S-EPMC9641784 | biostudies-literature
Project description:Hashimoto's thyroiditis, a common autoimmune disease, is associated with autoantibodies to thyroglobulin (Tg) and thyroid peroxidase (TPO). TPO, unlike abundant and easily purified Tg, is rarely investigated as an autoantigen in animals. We asked whether antibodies (Abs) develop to both TPO and Tg in thyroiditis that is induced (C57BL/6 and DBA/1 mice) or arises spontaneously (NOD.H-2h4 mice). Screening for TPOAbs was performed by flow cytometry using mouse TPO-expressing eukaryotic cells. Sera were also tested for binding to purified mouse Tg and human TPO. The antibody data were compared with the extent of thyroiditis. Immunization with mouse TPO adenovirus broke self-tolerance to this protein in C57BL/6 mice, but thyroiditis was minimal and TgAbs were absent. In DBA/1 mice with extensive granulomatous thyroiditis induced by Tg immunization, TPOAbs were virtually absent despite high levels of TgAbs. In contrast, antibodies to mouse TPO, with minimal cross-reactivity with human TPO, arose spontaneously in older (7-12 months) NOD.H-2h4 mice. Unexpectedly, TgAbs preceded TPOAbs, a time course paralleled in relatives of probands with juvenile Hashimoto's thyroiditis. These findings demonstrate a novel aspect of murine and human thyroid autoimmunity, namely breaking B cell self-tolerance occurs first for Tg and subsequently for TPO.
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Project description:OBJECTIVES:Although several studies have shown that cigarette smoking is associated with thyroid stimulating hormone (TSH), thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb), the exact relationship between smoking and thyroid function is controversial. As little is known about the effects of smoking on TSH, TPOAb and TgAb in Chinese residents. This study aimed to evaluate the association between cigarette smoking and TSH, TPOAb and TgAb in ten-city residents of China. STUDY DESIGN:This was a population-based cross-sectional study. METHODS:In this cross-sectional study, 15,181 subjects from ten major cities of China were investigated. Data regarding demographic characteristics, smoking status and consumption of iodine status were collected using in-person interviews based on a self-designed structured questionnaire. Serum concentrations of TSH, TPOAb and TgAb were measured using electrochemiluminescence immunoassays. Univariate analysis and multivariate linear stepwise regression analyses were used to analyze the data. RESULTS:The regular smokers had lower concentrations of TSH, TPOAb and TgAb than occasional smokers, former smokers and never smokers. Multivariate analysis demonstrated that regular smoking was associated with the decreased concentrations of TSH (? = -0.178), TPOAb (? = -0.287) and TGAb (? = -0.453) after adjusting other factors. Furthermore, daily smoking number was significantly associated with the decreased level of TSH (? = -0.045) and TPOAb(? = -0.080), and smoking duration was associated with the decreased TSH level (? = -0.030). CONCLUSIONS:Our findings suggest that cigarette smoking is related to a significant decline in the concentrations of TSH, TPOAb and TgAb. In addition, daily smoking number and long-term smoking decrease serum TSH and TPOAb levels. Cigarette smoking plays a significant role in the development of thyroid dysfunction.
| S-EPMC6876836 | biostudies-literature
Project description: Not available
| S-EPMC5339110 | biostudies-literature
Project description:Thyroglobulin (Tg), stored in the follicular lumen, has also been shown recently to perform two unexpected roles: as an autocrine negative-feedback suppressor of thyroid function in the presence of TSH and as a potent inducer of thyroid cell growth in the absence of TSH. However, the underlying molecular mechanism(s) remain unclear. To elucidate a molecular pathway linking Tg to increased cell proliferation, we examined the regulation of microRNAs (miRNAs) by Tg using an miRNA microarray. We identified 21 miRNAs whose expression was significantly suppressed by Tg in rat thyroid FRTL-5 cells. Using specific miRNA analogs, we determined that miR-16, miR-24, and miR-195 mediate the induction of thyroid cell growth by Tg. The expression of miR-16 and miR-195 target genes, Mapk8, Ccne1, and Cdc6, which were previously shown to be essential for TSH-stimulated thyroid cell growth, were also induced by Tg. Moreover, the Tg-induced expression of these genes was reduced by overexpression of miR-16 and miR-195. Similarly, the induction of c-Myc by Tg was reduced by miR-24 overexpression. These results suggest that Tg could alter thyroid cell proliferation by increasing the expression of cell division-related genes such as Mapk8, Ccne1, Cdc6, and c-Myc through its suppression of specific microRNAs (miR-16, miR-24, and miR-195). In addition, we identified phosphatidylinositol 3-kinase as a key signaling pathway, linking Tg with cell proliferation. The present data support an important role for miRNAs as effectors for the effect of Tg on cell proliferation and perhaps other functions of Tg in the thyroid cell.
| S-EPMC5414927 | biostudies-literature
Project description:Context:Autoimmune thyroid diseases (AITDs) arise from complex interactions among genetic, epigenetic, and environmental factors. Thyroglobulin (TG) is a major susceptibility gene for both Graves disease and Hashimoto thyroiditis. Interferon-? (IFN?), a cytokine secreted during viral infections, has emerged as a key trigger of AITD. We have shown that IFN? upregulates TG transcription; however, how the upregulation of TG transcription by IFN? triggers AITD is still unknown. Objective:To evaluate how IFN? triggers AITD by testing its effects on TG processing. Design:We exposed human thyroid cells to IFN? and evaluated its effects on TG expression and processing. Results:Human thyroid cells exposed to INF? had increased levels of TG mRNA but reduced TG protein levels, indicating TG protein degradation. IFN? induced endoplasmic reticulum stress, but surprisingly, neither the use of chemical chaperones nor proteasome inhibitor prevented IFN?-induced TG degradation. IFN? also increased LysoTracker staining and autophagy flux measured by net light chain 3 (LC3)-II and p62 fluxes. In addition, expression of autophagy markers LC3 and autophagy-related gene 5 was higher in thyroid tissues from patients with AITD. Finally, blocking lysosomal degradation prevented IFN?-induced degradation of TG. Conclusion:We have shown in this study IFN?-induced lysosomal-dependent degradation of TG in human thyroid cells. Our findings suggest that during viral infections, local thyroidal IFN? production can lead to lysosomal TG degradation, releasing pathogenic TG peptides that can trigger AITD.
| S-EPMC6179164 | biostudies-literature
Project description:Complete absence of thyroid hormone is incompatible with life in vertebrates. Thyroxine is synthesized within thyroid follicles upon iodination of thyroglobulin conveyed from the endoplasmic reticulum (ER), via the Golgi complex, to the extracellular follicular lumen. In congenital hypothyroidism from biallelic thyroglobulin mutation, thyroglobulin is misfolded and cannot advance from the ER, eliminating its secretion and triggering ER stress. Nevertheless, untreated patients somehow continue to synthesize sufficient thyroxine to yield measurable serum levels that sustain life. Here, we demonstrate that TGW2346R/W2346R humans, TGcog/cog mice, and TGrdw/rdw rats exhibited no detectable ER export of thyroglobulin, accompanied by severe thyroidal ER stress and thyroid cell death. Nevertheless, thyroxine was synthesized, and brief treatment of TGrdw/rdw rats with antithyroid drug was lethal to the animals. When untreated, remarkably, thyroxine was synthesized on the mutant thyroglobulin protein, delivered via dead thyrocytes that decompose within the follicle lumen, where they were iodinated and cannibalized by surrounding live thyrocytes. As the animals continued to grow goiters, circulating thyroxine increased. However, when TGrdw/rdw rats age, they cannot sustain goiter growth that provided the dying cells needed for ongoing thyroxine synthesis, resulting in profound hypothyroidism. These results establish a disease mechanism wherein dead thyrocytes support organismal survival.
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Project description:ObjectiveThyroglobulin antibodies (TgAb), principally comprising immunoglobulin G (IgG), are frequently found in healthy individuals. Previously, we showed that the glycosylation levels of TgAb IgG differed across various thyroid diseases, suggesting an important role of glycosylation on antibodies in the pathogenesis of thyroid diseases. Since IgG1 and IgG4 are the primary TgAb IgG subclasses, this study aimed to investigate the glycosylation of TgAb IgG1 and IgG4 subclasses in thyroid diseases.MethodsTgAb IgG was purified by affinity chromatography from the serum of patients with Hashimoto's thyroiditis (HT) (n = 16), Graves' disease (GD) (n = 8), papillary thyroid carcinoma (PTC) (n = 6), and PTC with histological lymphocytic thyroiditis (PTC-T) (n = 9) as well as healthy donors (n = 10). TgAb IgG1 and IgG4 concentrations were determined by enzyme-linked immunosorbent assay, and a lectin microassay was used to assess TgAb IgG1 and IgG4 glycosylation.ResultsSignificantly elevated mannose, sialic acid, and galactose levels on TgAb IgG1 were found in HT and PTC patients compared to GD patients and healthy controls (all p < 0.05). The mannose, sialic acid, and core fucose levels on TgAb IgG1 in PTC-T patients were higher than in healthy controls (all p < 0.05). Additionally, TgAb IgG1 from PTC-T patients exhibited lower sialylation than that from patients with PTC and higher fucosylation than that from patients with HT (both p < 0.05). However, TgAb IgG4 glycosylation did not differ among the five groups (p < 0.05).ConclusionOur study describes different distributions of TgAb IgG1 glycosylation in various thyroid diseases. The aberrantly increased glycosylation levels of TgAb IgG1 observed in HT, PTC, and PTC-T might be indicative of immune disorders and participate in the pathogenesis of these diseases.
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Project description:Thyroglobulin (Tg) is a secreted iodoglycoprotein serving as the precursor for triiodothyronine and thyroxine hormones. Many characterized Tg gene mutations produce secretion-defective variants resulting in congenital hypothyroidism. Tg processing and secretion is controlled by extensive interactions with chaperone, trafficking, and degradation factors comprising the secretory proteostasis network. While dependencies on individual proteostasis network components are known, the integration of proteostasis pathways mediating Tg protein quality control and the molecular basis of mutant Tg misprocessing remain poorly understood. We employ a multiplexed quantitative affinity purification-mass spectrometry approach to define the Tg proteostasis interactome and changes between WT and several congenital hypothyroidism variants. Mutant Tg processing is associated with common imbalances in proteostasis engagement including increased chaperoning, oxidative folding, and engagement by targeting factors for endoplasmic reticulum-associated degradation. Furthermore, we reveal mutation-specific changes in engagement with N-glycosylation components, suggesting distinct requirements for 1 Tg variant on dual engagement of both oligosaccharyltransferase complex isoforms for degradation. Modulating dysregulated proteostasis components and pathways may serve as a therapeutic strategy to restore Tg secretion and thyroid hormone biosynthesis.
| S-EPMC7950113 | biostudies-literature
Project description:Background: Most patients with thyroid cancer typically receive thyroidectomy with ablative radioactive iodine therapy. Such patients were followed with thyroid ultrasonography and serial serum thyroglobulin evaluation. Exosomes are nanovesicles secreted into extracellular environments, including plasma, saliva, urine, and other body fluids of patients with cancer. We try to find the early prognostic and exosomal biological markers of urine. Methods: We analyzed urinary exosomal proteins, including thyroglobulin and galectin-3, to identify early prognostic biological markers in urine for patients receiving operation and radioactive iodine ablative therapy. We enrolled sixteen newly diagnosed patients with papillary thyroid carcinoma and follicular thyroid carcinoma. We collect all patient's urine samples before operation, immediately after operation, post-operatively at three and six months (4 collections per patient). The levels of pre-operative and post-ablative of U-Ex Tg and galectin-3 in patients with thyroid cancer were measured. Results: Trends in urinary thyroglobulin concentrations in patients with post-ablative thyroid cancer were detected in the first sixteen patients. Importantly, serum thyroglobulin was not detected in five patients after operation and radioactive I-131 ablation, while U-Ex Tg still showed an increasing trend, which implicating the probable recurrence of thyroid cancer. This is the first study to evaluate whether U-Ex Tg is a future biological marker as a substitute for serum thyroglobulin. Conclusion: Our study have developed a brand-new evaluation for tracking thyroid cancer. The most useful scenario in using a test that is potentially more sensitive than existing serological testing is to eliminate the suspicion of recurrence and remove subjects from long term follow up. Trial Registration: ClinicalTrials.gov: NCT02862470; 5, August 2016. https://clinicaltrials.gov/ct2/show/NCT02862470?term=NCT02862470&rank=1. ClinicalTrials.gov: NCT03488134; 3, August 2018. https://clinicaltrials.gov/ct2/show/NCT03488134?term=NCT03488134&draw=2&rank=1.
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