Thyroid Receptor Research Articles

Comparative Effects of Di-(2-ethylhexyl)phthalate and Di-(2-ethylhexyl)terephthalate Metabolites on Thyroid Receptors: In Vitro and In Silico Studies.

Plasticizers added to polyvinylchloride (PVC) used in medical devices can be released into patients’ biological fluids. Di-(2-ethylhexyl)phthalate (DEHP), a well-known reprotoxic and endocrine disruptor, must be replaced by alternative compounds. Di-(2-ethylhexyl) terephthalate (DEHT) is an interesting candidate due to its lower migration from PVC and its lack of reprotoxicity. However, there is still a lack of data to support the safety of its human metabolites with regard to their hormonal properties in the thyroid system. The effects of DEHT metabolites on thyroid/hormone receptors (TRs) were compared in vitro and in silico to those of DEHP. The oxidized metabolites of DEHT had no effect on T3 receptors whereas 5-hydroxy-mono-(ethylhexyl)phthalate (5-OH-MEHP) appeared to be primarily an agonist for TRs above 0.2 µg/mL with a synergistic effect on T3. Monoesters (MEHP and mono-(2-ethylhexyl)terephthalate, MEHT) were also active on T3 receptors. In vitro, MEHP was a partial agonist between 10 and 20 µg/mL. MEHT was an antagonist at non-cytotoxic concentrations (2–5 µg/mL) in a concentration-dependent manner. The results obtained with docking were consistent with those of the T-screen and provide additional information on the preferential affinity of monoesters and 5-OH-MEHP for TRs. This study highlights a lack of interactions between oxidized metabolites and TRs, confirming the interest of DEHT.

Mapping multiple endocrine disrupting activities in Virginia rivers using effect-based assays

Water sources are frequently contaminated with natural and anthropogenic substances having known or suspected endocrine disrupting activities; however, these activities are not routinely measured and monitored. Phenotypic bioassays are a promising new approach for detection and quantitation of endocrine disrupting chemicals (EDCs). We developed cell lines expressing fluorescent chimeric constructs capable of detecting environmental contaminants which interact with multiple nuclear receptors. Using these assays, we tested water samples collected in the summers of 2016, 2017 and 2018 from two major Virginia rivers. Samples were concentrated 200× and screened for contaminants interacting with the androgen (AR), glucocorticoid (GR), aryl hydrocarbon (AhR) and thyroid receptors. Among 45 tested sites, over 70% had AR activity and 60% had AhR activity. Many sites were also positive for GR and TRβ activation (22% and 42%, respectively). Multiple sites were positive for more than one type of contaminants, indicating presence of complex mixtures. These activities may negatively impact river ecosystems and consequently human health.

Conformational Changes of Thyroid Receptors in Response to Antagonists.

Thyroid hormone receptors (TRs) play a critical role in human development, growth, and metabolism. Antagonists of TRs offer an attractive strategy to treat hyperthyroidism without the disadvantage of a delayed onset of drug action. While it is challenging to examine the atomistic behavior of TRs in a laboratory setting, computational methods such as molecular dynamics (MD) simulations have proven their value to elucidate ligand-induced conformational changes in nuclear receptors. Here, we performed MD simulations of TRα and TRβ complexed to their native ligand triiodothyronine (T3) as well as several antagonists. Based on the examination of 27 μs MD trajectories, we showed how binding of these compounds influences various structural features of the receptors including the helicity of helices 3 and 10 as well as the location of helix-12. Helices 3 and 12 are known to mediate coactivator association required for downstream signaling, suggesting these changes to be the molecular basis for TR antagonism. A mechanistic analysis of the trajectories revealed an allosteric pathway between H3 and H12 to be responsible for the conformational adaptations. Even though a mechanistic understanding of conformational adaptations triggered by TR antagonists is important for the development of novel therapeutics, they have not been previously examined in detail as it was done here.

The prognostic value of thyroid-stimulating immunoglobulin in the management of Graves' disease.

Background:The bioassay of thyroid-stimulating immunoglobulin was reported to have a similar performance to the commonly used thyroid-stimulating hormone binding inhibition assay, also known as thyroid receptor antibody assay. The normal reference range of thyroid receptor antibody levels indicates the withdrawal of anti-thyroid drugs in the recent clinical guidelines.Methods:A prospective, longitudinal observational study was conducted to evaluate the prognostic value of thyroid-stimulating immunoglobulin in patients with Graves’ disease.Results:A total of 77 patients with Graves’ disease treated with anti-thyroid drugs were in a continuous follow-up until 1 year after anti-thyroid drugs discontinuation. Commercial kits of thyroid-stimulating immunoglobulin and M22-thyroid-stimulating hormone binding inhibition assay were used and compared. Thyroid-stimulating immunoglobulin was all negative in healthy controls, Hashimoto thyroiditis, and subacute thyroiditis. Thyroid-stimulating immunoglobulin value was highest in untreated patients with Graves’ disease (p < 0.001). Under anti-thyroid drugs treatment, thyroid-stimulating immunoglobulin value decreased gradually. A total of 21 patients had positive thyroid-stimulating immunoglobulin at the end of treatment. According to clinical fate of patients with Graves’ disease after withdrawal of anti-thyroid drugs, thyroid-stimulating immunoglobulin value and positivity in patients with relapse were significantly higher than that reported in patients with remission (p = 0.001, p < 0.001). After adjustment for age, gender, initial thyroid receptor antibody, initial thyroid-stimulating immunoglobulin, and thyroid receptor antibody at the end of treatment, the odds ratio of positive thyroid-stimulating immunoglobulin for the risk of relapse was 33.271 (95% confidence interval: 4.741–233.458, p < 0.001) and odds ratio of quantitative thyroid-stimulating immunoglobulin was 1.009 (95% confidence interval: 1.002–1.015, p < 0.001).Conclusion:Thyroid-stimulating immunoglobulin is a good predictor of relapse in patients with Graves’ disease treated with anti-thyroid drugs. It might be safer to discontinue anti-thyroid drugs when thyroid-stimulating immunoglobulin and thyroid receptor antibody were both negative.

Computational evaluation of endocrine activity of biocidal active substances

Exposure to endocrine disrupting chemicals is an important public health concern although only a few endocrine disruption chemicals have been identified so far. To speed up their identification, in silico toxicological models appear to be the most appropriate, since the potential endocrine disruption of a large number of compounds can be estimated in a short time. In this study three in silico models (Endocrine disruptome software, VirtualToxLab and COSMOS KNIME) have been used. In silico predictions of the endocrine disruption potential of biocidal active substances have been made and predictions then compared with the available in vitro experimental binding affinities to androgen, estrogen, glucocorticoid and thyroid receptors. The chosen models had similar accuracies (around 60%), while differences were shown between the models in specificity and sensitivity. VirtualToxLab was the most balanced model. Additionally, three combined models were prepared and evaluated. As expected, the majority rule approach model was more accurate and balanced. However, the positive consensus rule model, that improved the specificity of predictions (≥80% for all studied nuclear receptors) was more applicable. This reduction of false positive predictions is especially useful in the search for positive (active) compounds. On the other hand, the novel negative consensus rule model improved the specificity of prediction (≥80% for all studied nuclear receptors), giving good predictions of negative (inactive) compounds that can be excluded from further testing. The results obtained by these combined models have great added value, since they can significantly reduce further experimental testing.

Characterization of adipogenic, PPARγ, and TRβ activities in house dust extracts and their associations with organic contaminants

In this study, we sought to expand our previous research on associations between bioactivities in dust and associated organic contaminants. Dust samples were collected from central NC homes (n = 188), solvent extracted, and split into two fractions, one for analysis using three different bioassays (nuclear receptor activation/inhibition and adipocyte development) and one for mass spectrometry (targeted measurement of 124 organic contaminants, including flame retardants, polychlorinated biphenyls, perfluoroalkyl substances, pesticides, phthalates, and polycyclic aromatic hydrocarbons). Approximately 80% of dust extracts exhibited significant adipogenic activity at concentrations that are comparable to estimated exposure for children and adults (e.g. ~20 μg/well dust) via either triglyceride accumulation (65%) and/or pre-adipocyte proliferation (50%). Approximately 76% of samples antagonized thyroid receptor beta (TRβ), and 21% activated peroxisome proliferator activated receptor gamma (PPARγ). Triglyceride accumulation was significantly correlated with TRβ antagonism. Sixty-five contaminants were detected in at least 75% of samples; of these, 26 were correlated with adipogenic activity and ten with TRβ antagonism. Regression models were used to evaluate associations of individual contaminants with adipogenic and TRβ bioactivities, and many individual contaminants were significantly associated. An exploratory g-computation model was used to evaluate the effect of mixtures. Contaminant mixtures were positively associated with triglyceride accumulation, and the magnitude of effect was larger than for any individually measured chemical. For each quartile increase in mixture exposure, triglyceride accumulation increased by 212% (RR = 3.12 and 95% confidence interval: 1.58, 6.17). These results suggest that complex mixtures of chemicals present in house dust may induce adipogenic activity in vitro at environmental concentrations and warrants further research.

Crosstalk of cholinergic pathway on thyroid disrupting effects of the insecticide chlorpyrifos in zebrafish (Danio rerio)

Chlorpyrifos is a widely used organophosphate insecticide and ubiquitously detected in the environment. However, little attention has been paid to its endocrine disrupting effect to non-target organisms. In the present study, zebrafish was exposed to 13 and 65 μg/L of chlorpyrifos for 7 and 10 days to determine the induced neurotoxicity and the alteration of thyroid metabolism. The 120 h LC50 and LC10 of chlorpyrifos was estimated as 1.35 mg/L and 0.62 mg/L based on the acute embryo toxicity assay, respectively. The acetylcholinesterase (AChE) inhibitory was detected by 13 μg/L chlorpyrifos and could be reversed by the co-exposure of 100 and 1000 μg/L anticholinergic agent atropine. For thyroid hormone level, 13 and 65 μg/L of chlorpyrifos induced increased free T3 levels in 10 dpf (days post-fertilization). The expression of thyroid related genes in 7 and 10 dpf exposed zebrafish were measured by the quantitative Real-Time PCR (qRT-PCR) assay. The mRNA expression of tshba, thrb, crhb, ttr, tpo, ugt1ab and slc5a5 had significant change. However, the alterations of thyroid hormone and mRNA expression could be partly rescued by the addition of atropine. The molecular docking of chlorpyrifos and T3 to the thyroid receptor β in zebrafish using homology modelling and CDOCKER procedures shown weaker binding ability of chlorpyrifos compared to T3. Therefore, we concluded that the disturbance of thyroid signaling in zebrafish might arise from the developmental neurotoxicity induced by chlorpyrifos.

Thyroid Receptor Antagonism of Chemicals Extracted from Personal Silicone Wristbands within a Papillary Thyroid Cancer Pilot Study.

Research suggests that thyroid cancer incidence rates are increasing, and environmental exposures have been postulated to be playing a role. To explore this possibility, we conducted a pilot study to investigate the thyroid disrupting bioactivity of chemical mixtures isolated from personal silicone wristband samplers within a thyroid cancer cohort. Specifically, we evaluated TRβ antagonism of chemical mixtures extracted from wristbands (n = 72) worn by adults in central North Carolina participating in a case-control study on papillary thyroid cancer. Sections of wristbands were solvent-extracted and analyzed via mass spectrometry to quantify a suite of semivolatile chemicals. A second extract from each wristband was used in a bioassay to quantify TRβ antagonism in human embryonic kidney cells (HEK293/17) at concentrations ranging from 0.1 to 10% of the original extract (by volume). Approximately 70% of the sample extracts tested at a 1% extract concentration exhibited significant TRβ antagonism, with a mean of 30% and a range of 0-100%. Inhibited cell viability was noted in >20% of samples that were tested at 5 and 10% concentrations. Antagonism was positively associated with wristband concentrations of several phthalates, organophosphate esters, and brominated flame retardants. These results suggest that personal passive samplers may be useful in evaluating the bioactivities of mixtures that people contact on a daily basis. We also report tentative associations between thyroid receptor antagonism, chemical concentrations, and papillary thyroid cancer case status. Future research utilizing larger sample sizes, prospective data collection, and measurement of serum thyroid hormone levels (which were not possible in this study) should be utilized to more comprehensively evaluate these associations.

Thyroid and androgen receptor signaling are antagonized by μ-Crystallin in prostate cancer.

Androgen deprivation therapy (ADT) remains a key approach in the treatment of prostate cancer (PCa). However, PCa inevitably relapses and becomes ADT resistant. Besides androgens, there is evidence that thyroid hormone thyroxine (T4) and its active form 3,5,3′‐triiodo‐l‐thyronine (T3) are involved in the progression of PCa. Epidemiologic evidences show a higher incidence of PCa in men with elevated thyroid hormone levels. The thyroid hormone binding protein μ‐Crystallin (CRYM) mediates intracellular thyroid hormone action by sequestering T3 and blocks its binding to cognate receptors (TRα/TRβ) in target tissues. We show in our study that low CRYM expression levels in PCa patients are associated with early biochemical recurrence and poor prognosis. Moreover, we found a disease stage‐specific expression of CRYM in PCa. CRYM counteracted thyroid and androgen signaling and blocked intracellular choline uptake. CRYM inversely correlated with [18F]fluoromethylcholine (FMC) levels in positron emission tomography/magnetic resonance imaging of PCa patients. Our data suggest CRYM as a novel antagonist of T3‐ and androgen‐mediated signaling in PCa. The role of CRYM could therefore be an essential control mechanism for the prevention of aggressive PCa growth.

Thyroid Hormones, Silencing Mediator for Retinoid and Thyroid Receptors and Prognosis in Primary Breast Cancer.

Silencing mediator of retinoid and thyroid receptors (SMRT) is a nuclear corepressor in thyroid and estrogen hormones pathways. The aim was to evaluate SMRT expression in relation to thyroid hormone levels and prognostic markers in breast cancer (BC). Serum and tumor tissues were obtained from 36 patients with benign breast disease (BBD) and 79 BC patients. SMRT expression was determined by immunohistochemistry. Free-triiodothyronine (FT3), free thyroxine (FT4) and thyroid-stimulating hormone (TSH) were measured in serum. Higher FT4, lower FT3/FT4 ratio and higher expression of SMRT were found in BC compared to BBD (for all p<0.001). In BC, increased SMRT expression was associated with lower FT3 (p=0.028), higher tumor grade (p=0.031), increased KI67 proliferation index (p=0.015), higher risk of recurrence (p=0.014) and shorter disease-free survival (p=0.006). In multivariate analysis, SMRT overexpression and below-median levels of TSH were independent prognostic factors in BC. Elevated FT4 and decreased FT3/FT4 in BC patients suggest a role for thyroid hormones in malignant transformation. SMRT tumor overexpression is associated with lower FT3 levels, tumor proliferative activity and an aggressive clinical course.

Double trouble - thyro-pericarditis: rare presentation of Graves' disease as pericarditis-a case report.

BackgroundAcute pericarditis is frequently encountered in clinical practice; however, pericarditis as the first presentation of Graves' disease is rare and mainly limited to case reports in the literature. We hereby report a case in which a young patient presented with pericarditis as the first manifestation of Graves’ disease.Case summaryA 24-year-old male was admitted to hospital with presenting complaint of left-sided chest pain, gradual in onset, 6/10 in intensity, sharp in character, increased by deep breathing and improved by leaning forward. Patient also gave a history of insomnia, unintentional weight loss despite a good appetite, heat intolerance, and anxiety. On clinical examination, the patient had features of thyrotoxicosis, i.e., tachycardia, high volume pulse, and sweaty palms with fine tremors. There was no associated pericardial rub. Neck examination shows diffuse, non-tender goitre. Electrocardiogram findings were consistent with acute pericarditis. His thyroid function tests demonstrated hyperthyroidism and anti-thyroglobulin antibodies were also significantly elevated. Echocardiogram showed preserved left ventricular systolic function and a small global pericardial effusion without any signs of tamponade. He was diagnosed with Graves’ disease revealing itself as pericarditis and was started on ibuprofen, beta-blockers, and carbimazole. Patient had marked clinical and biochemical improvement on 3 monthly follow-ups.DiscussionThyro-pericarditis is a rare entity, and limited literature is available regarding this combination. The exact aetiology of Graves associated pericarditis is unknown. There is a possibility of interaction of autoantibodies with receptors on pericardium. Diagnosis is based on a detailed history, clinical examination, supplemented by relevant investigations (elevated free T4 and thyroid receptor antibodies, suppressed thyroid stimulating hormone (TSH) and Imaging via ultrasound). Mainstay of treatment includes non-steroidal anti-inflammatory drugs, beta-blockers, and anti-thyroidal medications.

Protein-affinity guided identification of chlorinated paraffin components as ubiquitous chemicals

Chlorinated paraffins (CPs) have been extensively examined to identify their components. Short-chain CPs with a carbon number of 10–13 have been strictly restricted or banned due to their addition to the list of Persistent Organic Pollutants in the world. However, more constituents with potential toxicities in these complicated mixtures are still unclear. In the present study, a purification method based on the protein affinity of thyroid hormone-related proteins (transthyretin and thyroid receptor) was established. The protein-based affinity extraction coupled with high-throughput scanning successfully discover a new group of chlorinated compounds (CP(O2)) in commercial CP mixtures. The CP(O2)s were purified from the commercial mixtures and identified to be chlorinated fatty acid methyl esters (CFAMEs) with a carbon chain length of 17–19 and 3–11 chlorines by a combination of liquid-liquid extraction, hydrolysis, Fourier transform infrared spectrometry and Orbitrap mass spectrometry. The newly identified CFAMEs were found to be ubiquitous in the environmental matrices, and concentration ratios of ∑CFAMEs/∑CPs ranged from 0.01 to 35 in air, soil and food samples. CFAMEs were also detected in blood samples of general populations, and accumulated in humans through dietary uptake. CFAMEs can compete with T4 for binding TTR with higher potencies than CPs, possibly leading to disruptions of thyroid hormone homeostasis.

Thyroid Crisis and Septic Suspected Sepsis in the First Trimester of Pregnancy

A normal pregnancy with physiological and hormonal changes can change thyroid function, accordingly, there are difficulties to establish the diagnosis of thyroid abnormality. The prevalence of hyperthyroidism in pregnancy is 0.6%. Approximately 1-2% of hyperthyroidism develops into a thyroid crisis. Knowledge of the diagnosis of the thyroid crisis in a pregnant female is very important to avoid complications. The 22-year-old female of thirteen weeks presented with vomiting, since two days before hospitalized, weakness, and decreased consciousness. During treatment, patients had diarrhea, melena, and was irritable. Physical examination showed blood pressure of 136/112 mmHg, pulse of 110 times/minute, respiration of 24 times/minute, and temperature of 38.3oC. Exophthalmos was found at the patient's eyes, but there was no enlargement of the thyroid and the patient often screamed hysterically. Routine urine examination showed proteinuria 1+, blood 3+, leukocytes 1+ in urinalysis, FT4 35.18 pmol/L and TSH &lt;0.05 uIU/mL, leukocytes 15.2 x103/uL, SGOT 245 U/L, SGPT 366 U/L. The final diagnosis of this patient is a thyroid crisis and suspect sepsis in the first trimester of pregnancy. Thyroid Receptor Antibody (TRAb) examination should be performed to assure Graves disease or hyperthyroidism due to pregnancy (transient hyperthyroidism) as the cause.

Assessment of the endocrine-disrupting potential of halogenated parabens: An in silico approach

Parabens are endocrine-disrupting chemicals present in a variety of pharmaceutical and personal care products. Due to their wide-spread use, significant amounts are also released into the aquatic domain of the environment. During water disinfection, parabens give rise to halogenated transformation products. As opposed to parabens, there is considerable lack of knowledge with regard to the endocrine-disrupting potential of their halogenated counterparts, which presents a challenge for regulatory decision making. We aimed to fill this knowledge gap by using the Endocrine Disruptome and VirtualToxLab™ to predict their endocrine-disrupting potential on the basis of calculated affinities for different nuclear receptors. The applied computational approach indicates a high probability of halogenated parabens binding to glucocorticoid, thyroid and aryl hydrocarbon receptors and suggests that disinfection is likely to form transformation products with more pronounced endocrine-disrupting activities than those of parent parabens. The obtained results not only highlight the need for additional in vitro/in vivo investigations of these chemicals as endocrine disruptors but also provide a means of guiding and prioritizing these future studies, in order to assess fully their hazard to human health.

Features of the Eye Hydrodynamics on the Background of Thyroid Dysfunctions

Purpose: to study the features of eye hydrodynamics in patients with thyroid dysfunctions.Patients and methods. The material for this study was the results of a survey of 43 patients (86 eyes) with thyroid dysfunctions: 23 people (46 eyes) with primary untreated hypothyroidism (PGT) and 20 people (40 eyes) with primary untreated thyrotoxicosis (PTT). There weren’t ophthalmic hypertension and glaucoma There weren’t signs of ophthalmic hypertension and glaucoma in the patients included in this study at the stage of primary ophthalmologic diagnostics.Results. Correlation analysis revealed a causal relationship between the ratio of T4 / TSH hormones, on the one hand, and indicators of secretion of aqueous humor per unit of time and ease of outflow, on the other hand. In the group of patients with hypothyroidism, a weak linear inverse correlation was found between the ratio of free thyroxine and thyroid stimulating hormone and the minute volume of aqueous humor: according to the regression model, an increase in the ratio of T4 / TSH hormones by 1 was accompanied by a decrease in the minute volume of aqueous humor by 3 units. In patients with thyrotoxicosis, a statistically significant inverse linear correlation was found between the ratio of the T4 / TSH hormones and the coefficient of ease of outflow. According to the regression model, with an increase in the ratio of hormones T4 / TSH by 1, the coefficient of lightness of outflow decreases by 5 units. The presence of thyroid receptors in the cytoplasm and nuclei of the endothelium cells of the trabecular apparatus, the nuclei of fibroblasts forming the stroma of the trabeculae, as well as in the nuclei of the pigment and non-pigment epithelium of the processes of the ciliary body substantiates the molecular basis of the causal connection of thyroid dysfunctions with hydrodynamic disorders The conducted studies confirm the modern concept that the control of regulation of the tissue and organ homeostasis is carried out by the coordinated interaction of 3 systems: nervous, endocrine, and immune. Regression modeling clearly shows a pronounced causal relationship between thyroid dysfunctions and hydrodynamic processes in the eye.Conclusion. The results of clinical studies demonstrate the fact of controlling regulation by hydrodynamic processes at the eye level by the endocrine system, explain the possible mechanism on a morphological basis, and reveal the potential of a new therapeutic strategy.

Characterization of protein expression of thyroid-responsive genes in cardiomyocyte PTP1B knockout mice in cardiac hypertrophy

Excessive Reactive Oxygen Species (ROS) production is involved in cardiac pathologies such as hypertrophy. Protein tyrosine phosphatases are regulated by reversible oxidation via ROS production. We demonstrated that in murine hearts undergoing hypertrophy, ROS production was associated with inactivation of the protein tyrosine phosphatase PTP1B. Moreover, PTP1B cardiac knockout (cKO) mice showed an exacerbated cardiac hypertrophy when subjected to pressure overload by transverse aortic constriction (TAC). Preventing thyroid hormone synthesis reversed the PTP1B-inactivation-driven pathological remodeling. Our aim was to investigate the protein expression of thyroid hormone-responsive genes possibly involved in the hypertrophic phenotype of TAC PTP1B cKO mice and in the bradycardia observed in cKO mice. 4 weeks post-surgery, TAC and sham hearts were harvested from control or PTP1B cKO mice for immunobloting from protein lysates. The protein expression of β-Myosin Heavy Chain (MHC), thyroid receptor alpha1 and beta 1 (TRα1, TRβ1), hyperpolarization-activated cyclic nucleotide-gated channels2/4 (HCN2, HCN4) and sarcoplasmic reticulum calcium ATPase2 (SERCA2) were studied. TAC hearts from PTP1B cKO mice showed a decreased expression of β-MHC and an increased expression of TRα1. TRβ1 was upregulated in both control and hypertrophic PTP1B cKO mice but SERCA2 or HCN4 protein levels did not show any significant differences between the two groups, subjected to TAC or not. Thyroid hormone signaling is altered following PTP1B inactivation in the heart and appears to occur mainly through changes in TRs isoforms expression. The limited sample size from our study ( n = 2) did not allow us to conclude definitely about HCN4 and SERCA2 expressions. Additional experiments will need to be performed to gain further insight on molecular mechanisms whereby PTP1B inactivation affects cardiac function and thyroid hormone signaling.

Harmonized Cross-Species Assessment of Endocrine and Metabolic Disruptors by Ecotox FACTORIAL Assay.

Environmental pollution is a threat to humans and wildlife species. Of particular concern are endocrine disrupting chemicals (EDCs). An important target of EDCs is nuclear receptors (NRs) that control endocrine and metabolic responses through transcriptional regulation. Owing in part to structural differences of NRs, adverse effects of EDCs vary significantly among species. Here, we describe a multiplexed reporter assay (the Ecotox FACTORIAL) enabling parallel assessment of compounds' effects on estrogen, androgen, thyroid, and PPARγ receptors of representative mammals, birds, reptiles, amphibians, and fish. The Ecotox FACTORIAL is a single-well assay comprising a set of species-specific, one-hybrid GAL4-NR reporter constructs transiently transfected into test cells. To harmonize cross-species assessments, we used a combination of two approaches. First, we used the same type of test cells for all reporters; second, we implemented a parallel detection of reporter RNAs. The assay demonstrated excellent quality, reproducibility, and insignificant intra-assay variability. Importantly, the EC50 values for NR ligands were consistent with those reported for conventional assays. Using the assay allowed ranking the hazard potential of environmental pollutants (e.g., bisphenols, polycyclic aromatic hydrocarbons, and synthetic progestins) across species. Furthermore, the assay permitted detecting taxa-specific effects of surface water samples. Therefore, the Ecotox FACTORIAL enables harmonized assessment of the endocrine and metabolic disrupting activity of chemicals and surface water in humans as well as in wildlife species.

Ethionamide Alters Thyroid Receptor Gene Expression in Rats' Muscle

BACKGROUND: Ethionamide usage as one of the drug regimens still becomes a challenge due to high numbers of patients developing hypothyroid. Ethionamide had been associated with the inhibition of thyroid hormone (TH) synthesis and interestingly, ethionamide (C8H10N2S)-induced hypothyroidism is supported by its similar structure with thioamides, propythiouracil (C7H8N2S). However, hypothyroidism is not solely caused by its production, it could be caused by signaling alteration. Therefore, knowing that important TH action is determined via genomic pathway, alteration of this receptor could bring serious clinical problem. Unfortunately, there is limited study about the regulation of ethionamide and its connection on TH genomic signaling especially thyroid hormone receptor (TR) gene expression in soleus, gastrocnemius and cardiac muscle.METHODS: Thirty-eight rats were divided into control, ethionamide and propylthiouracyl groups. After 12-week treatment, rat were sacrificed, then gastrocnemius, soleus and cardiac muscles were dissected out, snap freezed using liquid nitrogen, and stored in -80oC until use. RNA was extracted and run for reverse transcription polymerase chain reaction (RT-PCR).RESULTS: In soleus muscle, ethionamide stimulated TR mRNA expressions and deiodinase compared to control group. In contrast, TRα1 gene expression was not affected by ethionamide administration. In gastrocnemius muscle, only TRβ1 gene and Dio2 gene expressions that were significantly increased compared to control group. In cardiac muscle, ethionamide significantly stimulated all the thyroid hormone receptor isoform and iodothyronine deiodinase gene expression compared to the control group.CONCLUSION: Long ethionamide treatment upregulates TR gene expressions and deiodinase in soleus and cardiac muscle, there is different expression pattern of soleus, gastrocnemius and cardiac muscle after ethionamide stimulation.KEYWORDS: ethionamide, hypothyroid, TRα1, TRα2, TRβ1, TRβ2

Myasthenia Gravis and its Association With Thyroid Diseases.

Myasthenia gravis (MG) is a rare autoimmune neuromuscular junction disorder, and thyroid disorder is a disorder involving the thyroid receptor, of which Graves' disease (GD) is the most common autoimmune thyroid disorder, in which antibodies develop against thyroid receptors. Both may have similar clinical features. In myasthenia gravis, autoimmune antibodies develop against postsynaptic neuromuscular junction disrupting the neuromuscular transmission, resulting in fluctuating muscle weakness and fatigue. It is a disease of young women and older men. The two pathologies may coexist in a patient or can precede one another. Graves' disease (GD) among thyroid diseases is most often associated with MG. Similarities in clinical features lead to difficulty in distinguishing MG and GD. Despite the standard treatment of myasthenia gravis, including steroids, acetylcholinesterases, rituximab, immunosuppressants, and thymectomy, there is still an increased number of relapses and myasthenia crisis. Eculizumab and plasmapheresis are the two new treatment options for MG, with supporting evidence of marked improvement in recent studies. Myasthenia gravis and Graves' disease have a see-saw relationship. Treating one pathology may worsen the other, so physicians should always consider MG as a differential in patients of hyperthyroidism presenting with new symptoms of fatigue or respiratory failure or neuromuscular weakness.In this comprehensive review article, we tried to establish an association between myasthenia gravis and Graves' disease (GD) by exploring currently available literature from PubMed. However, more studies need to be done to establish an association between pathologies.

Pentabromoethylbenzene Exposure Induces Transcriptome Aberration and Thyroid Dysfunction: In Vitro, in Silico, and in Vivo Investigations.

Pentabromoethylbenzene (PBEB), as one of the novel brominated flame retardants (NFBRs), has caused increasing public concern for health risks. Till now, information regarding potential effects of PBEB on thyroid function remains unclear. Herein, we investigated thyroid disruption of PBEB in vitro and in silico and evaluated thyroid dysfunction induced by PBEB using Sprague-Dawley rats. PBEB showed thyroid receptor (TR) β antagonistic activity with IC50 of 9.82 × 10-7 M in the dual-luciferase reporter gene assay and induced relative reorientation of helix 11 (H11) and H12 of the TR ligand binding domain as revealed by molecular dynamics simulations. PBEB (0.2, 2, 20 mg/kg BW/d) markedly altered the transcriptome profile of thyroid with induction of 17, 42, and 119 differentially expressed genes (DEGs) involved in thyroid hormone signaling and synthesis pathway, of which transthyretin and albumin are common DEGs. The 28-d exposure to PBEB significantly decreased the triiodothyronine level (from 7.23 to 5.67 ng/mL) and increased the thyrotropin level (from 7.88 to 12.86 mU/L) for female rats. PBEB consequently reduced thyroid weight and altered its morphology with more depleted follicles. Overall, our study provides the first account of evidence on PBEB exerted thyroid disruption, transcriptome aberration, and morphological alteration, facilitating health risk assessment of PBEB and structurally related NBFRs.