Endothelin-1 levels in patients with disorders of the thyroid gland

The bidirectional relationship of thyroid disease and atrial fibrillation: Established knowledge and future considerations

Atrial fibrillation (AF) tends to occur frequently in patients with thyroid disease, primarily hyperthyroidism. In hyperthyroidism, increased levels of thyroid hormones, via intra- and extranuclear mechanisms, have profound effects on cardiac electrophysiology. Hypothyroidism carries a lower risk for AF and is mainly associated with the overtreatment of hypothyroid patients. New-onset AF is frequently the only manifestation of thyroid disease, which renders screening for thyroid dysfunction in that scenario clinically useful. Managing thyroid disease and comorbid AF is essential. This includes thyroid hormones control along with conventional AF therapy. However, there are several open issues with this comorbid duo. The optimal management of thyroid disease and its impact on AF burden remains obscure. There is scanty information on clear-cut benefits for therapy of subclinical thyroid disease and screening of asymptomatic patients. Furthermore, the immunogenetic overlap between the autoantibodies in Graves' disease and AF genesis may lead to novel therapeutic implications. The objective of this review is to summarize the up-to-date epidemiology, pathogenesis, pathophysiology and management of interacting thyroid disease and AF.

Occurrence of sporadic medullary thyroid carcinoma in Graves' disease in association with a RET proto-oncogene mutation

BACKGROUND

Graves' disease may be associated with thyroid cancer, particularly differentiated thyroid cancer. Medullary thyroid cancer (MTC) is less common. The occurrence of sporadic MTC in Graves' disease in the presence of a RET proto-oncogene has never been reported.

CLINICAL PRESENTATION

A 63-year-old woman was referred for Graves' disease. A thyroid ultrasound disclosed five nodules, one of which was classified as Eu-Tirads 5 with a size of 6.7 × 6.5× 11 mm. Fine needle aspiration was reported as Bethesda class IV follicular neoplasm of a Hürthle cell subtype. Calcitonin level was found to be elevated. A total thyroidectomy confirmed the diagnosis of MTC and a bilateral cervical lymphadenectomy was performed, with four lymph nodes being infiltrated by MTC. Genetic testing revealed a M918T mutation in the RET proto-oncogene.

CONCLUSION

MTC may occur in Graves' disease, especially if a nodule is present. In this case, genetic testing should always be performed even if MTC is sporadic. Increased incidence of thyroid cancer in autoimmune thyroid diseases, as well as the link existing between autoimmunity, inflammation and carcinogenesis, leads us to hypothesize that the association here reported is not coincidental.

Endothelin-1 axes in the framework of predictive, preventive and personalised (3P) medicine

Endothelin-1 (ET-1) is involved in the regulation of a myriad of processes highly relevant for physical and mental well-being; female and male health; in the modulation of senses, pain, stress reactions and drug sensitivity as well as healing processes, amongst others. Shifted ET-1 homeostasis may influence and predict the development and progression of suboptimal health conditions, metabolic impairments with cascading complications, ageing and related pathologies, cardiovascular diseases, neurodegenerative pathologies, aggressive malignancies, modulating, therefore, individual outcomes of both non-communicable and infectious diseases such as COVID-19. This article provides an in-depth analysis of the involvement of ET-1 and related regulatory pathways in physiological and pathophysiological processes and estimates its capacity as a predictor of ageing and related pathologies,a sensor of lifestyle quality and progression of suboptimal health conditions to diseases for their targeted preventionand as a potent target for cost-effective treatments tailored to the person.

miR‑27a‑3p regulates the inhibitory influence of endothelin 3 on the tumorigenesis of papillary thyroid cancer cells

Several studies on papillary thyroid cancer (PTC) have been performed. However, the effects of endothelin 3 (EDN3) and microRNA (miR)-27a-3p on PTC cells has yet to be investigated, to the best of the authors' knowledge. The present study aimed to explore the biological functions of EDN3 and miR-27a-3p in PTC cells. Bioinformatics analysis was conducted to identify possible key genes and miRs involved in PTC progression. Western blot analysis and reverse transcription-quantitative (RT-q) PCR were employed to confirm the key genes or miRs expressed in PTC cells. Cytological methods were used to detect cell viability, proliferation, apoptosis and migration and luciferase reporter assay was performed to confirm the relationship between END3 and miR-27a-3p. After analyzing the results of gene microarray analyses and RT-qPCR, EDN3 with low expression was identified as the key gene associated with PTC progression. It was also found that EDN3 overexpression in PTC cells impaired cell viability, proliferation and migration but promoted cell apoptosis. In addition, the findings revealed that miR-27a-3p could relieve the inhibitory influence of EDN3 on PTC cells by binding to EDN3 mRNA 3′ untranslated region (UTR), thereby suppressing EDN3 expression. Overall, the results of the present study demonstrated that by binding to EDN3 mRNA 3′UTR, miR-27a-3p could attenuate the inhibitory function of EDN3 in the tumorigenesis of PTC cells.

Plasma endothelin-1 levels are increased in atrial fibrillation patients with hyperthyroidism

BACKGROUND

Endothelin-1 (ET-1) is a potent vasoconstrictor, mitogen and inflammatory factor that may contribute to development of atrial fibrillation (AF). Plasma ET-1 levels are increased in hyperthyroid patients, but studies evaluating its relation to AF development in hyperthyroid patients are lacking.

OBJECTIVE

The present study seeks to evaluate the relation of plasma ET-1 to AF development as a function of thyroid status.

METHODS

Blood samples from euthyroid patients (n = 41), hypothyroid (n = 61), hyperthyroid (n = 41), AF with hyperthyroidism (n = 9), and euthyroid AF (n = 10) patients were collected. Plasma ET-1, CRP, and thyroid hormone levels were measured and compared between groups.

RESULTS

Plasma ET-1 levels were higher in hyperthyroid and euthyroid AF patients> hyperthyroid-non-AF > hypo and euthyroid non-AF patients. Plasma ET-1 levels positively correlated with free T3 and T4 levels, and negatively with TSH levels. By multivariate analysis, plasma ET-1 was positively associated with AF, hyperthyroidism, and age. Plasma CRP did not vary by study group in either univariate or multivariate analyses.

CONCLUSION

Plasma ET-1 is associated with AF, elevated in hyperthyroid patients and positively correlated with thyroid hormone levels, suggesting that hyperthyroidism may increase ET-1 expression and release. This study may guide development of novel predictors of AF associated with hyperthyroidism, and may help to personalize therapy in hyperthyroid patients.

The evaluation of endothelin 1 (EDN1) and endothelin receptor type A (EDNRA) gene polymorphisms in Hashimoto's thyroiditis

PURPOSE

Endothelin1 (EDN1) is well established marker of inflammation. The functions of EDN1 are mediated mainly by endothelin receptors type A (EDNRA). The etiopathogenesis of Hashimoto's thyroiditis (HT) remains still elusive although the role of chronic inflammation and subsequent endothelial dysfunction has been established. This study examined firstly the possible association of EDN1 (G5665Tand T-1370G) and EDNRA (C+70G and G-231A) single nucleotide polymorphisms (SNPs) with the occurrence of HT, and evaluates the relationship between genotypes and clinical/laboratory manifestation of HT.

MATERIALS AND METHODS

We analyzed genotype and allele distributions of above mentioned polymorphisms in 163 patients with HT and 181 healthy controls by real-time PCR combined with melting curve analysis.

RESULTS

No significant associations between HT and variant alleles of EDN1 5665 and -1370, as well as EDNRA +70 and -231 SNPs were found. Haplotype analysis demonstrated that there was a strong (D'=0.76, r(2)=0.487) and weak (D'=0.403, r(2)=0.086) linkage disequilibrium (LD) between EDN1 -1370 and 5665, and between EDNRA -231 and +70 SNPs, respectively. However, haplotype frequencies in patients were similar to those in controls. In addition, it was observed that the EDNRA +70 G allele had protective effect against early (at age before 40 years) disease onset of HT (OR: 0.51, 95% CI=0.32-0.79, p=0.003).

CONCLUSION

Although no significant associations between susceptibility to HT with EDN1 5665 and -1370, as well as with EDNRA+70 and -231 SNPs were found, EDNRA +70 polymorphism was related with decreased risk for early onset HT.

Polymorphisms of endothelin 1 (G5665T and T-1370G) and endothelin receptor type A (C+70G and G-231A) in Graves' disease

PURPOSE

Endothelin 1 (EDN1) is a strong angiogenic and mitogenic factor, playing a key role in hypervascularization, thyroid follicle cell hyperplasia, and lymphocyte infiltration in the thyroid gland of patients with Graves' disease (GD). EDN1 induces angiogenesis and mitogenesis via endothelin receptor type A (EDNRA). This study examined the possible association of EDN1 (G5665T and T-1370G) and EDNRA (C+70G and G-231A) single nucleotide polymorphisms (SNPs) with the occurrence of GD, and evaluates the relationship between genotypes and clinical/laboratory manifestations of GD.

MATERIALS AND METHODS

We analyzed genotype and allele distributions of EDN1 and EDNRA polymorphisms in 165 patients with GD and 181 healthy controls by real-time PCR combined with melting curve analysis.

RESULTS

No significant associations between GD and variant alleles of the studied polymorphisms were observed. However, the anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-TG) levels in EDN1 G5665T GG genotype were higher than those in T allele carriers (GT+TT) (p=0.001 and p=0.026, respectively). In addition, anti-TPO levels in EDN1 T-1370G wild-type homozygous patients were found to be higher than in mutant gene carrying patients (GT+GG) (p=0.006). The presence of EDNRA+70G allele was associated with 3.37-fold increased risk for development of ophthalmopathy in GD patients (p=0.009).

CONCLUSION

Although there were no associations between EDN1 (G5665T and T-1370G) and EDNRA (C+70G and G-231A) SNPs and susceptibility to GD, EDN1 G5665T and T-1370G polymorphisms were related to alterations of autoantibody production and EDNRA C+70G polymorphism is related with increased risk for ophthalmopathy in GD patients.

Decreased FKBP12.6 expression and enhanced endothelin receptor signaling associated with arrhymogenesis in myocardial infarction rats

An increased propensity towards cardiac arrhythmias and aggravated heart function is observed in myocardial infarction (MI), the development of which is associated with the calcium handling system in the myocardium. It was hypothesized that the abnormal changes in the MI model may be a consequence of the abnormal expression and function of the RyR2-FKBP12.6 channel complex and that these abnormalities may be related to an over-activated endothelin (ET) system. Salvianolic acid B is expected to suppress life-threatening arrhythmias and to restore the abnormality of the RyR2-FKBP12.6 complex in rats. MI was produced by ligating the coronary artery for 4 weeks. Salvianolic acid B (100 mg/kg/day, p.o. for 4 weeks) was administered to rats 0.5 h before surgery. Measurements of cardiac arrhythmias, cardiac function, calcium transient, cardiac calcium release channel handling proteins and the endothelin system were conducted. The aggravated arrhythmia and compromised cardiac function in MI rats was accompanied by elevated diastolic Ca(2+) levels in the cytosol and a significant down-regulation of expression of RyR2-FKBP12.6. These were closely linked with an over-activated ET pathway in the myocardium. After a 4-week treatment with salvianolic acid B, all abnormalities were reversed significantly. Salvianolic acid B was capable of normalizing FKBP12.6 expression levels and decreasing the propensity towards arrhythmias by attenuating the up-regulated ET pathway.

Downregulated FKBP12.6 expression and upregulated endothelin signaling contribute to elevated diastolic calcium and arrhythmogenesis in rat cardiomyopathy produced by l-thyroxin

BACKGROUND

Dissociation of FKBP12.6 from RyR2 is considered as an important molecular event resulting in calcium leak and an increased risk in arrhythmogenesis. We hypothesized that augmented ventricular fibrillation (VF) on reperfusion of rat cardiomyopathy induced by l-thyroxin may result from elevated diastolic Ca(2+) levels due to dissociation (downregulation) of FKBP12.6 and upregulation of endothelin (ET-1) signaling pathway.

METHODS

Rats were treated with l-thyroxin (0.4 mg/kg, s.c.) for 10 days. Dajisentan (CPU0213), a dual endothelin receptor antagonist (100 mg/kg p.o.), or propranolol was administered on day 6 to 10. Susceptibility to VF was evaluated on ischemia/reperfusion episode. mRNA expression of FKBP12.6, and ET-1 levels were determined. Calcium transients and FKBP12.6 immunohistochemistry were measured by confocal microscopy in isolated cardiomyocytes from cardiomyopathy.

RESULTS

Cardiomyopathy induced by l-thyroxin resulted in an increased susceptibility to VF on ischemia/reperfusion. Upregulated mRNA expression of RyR2 and PKA in association with downregulated FKBP12.6 expression was found in l-thyroxin-treated rats compared to controls. Calcium transients evoked by field electrical stimulation showed an increase in Ca(2+) by +75% during diastole. An increase in ET-1 (ng/mg protein) (+36.6%) and mRNA abundance of preproET-1 were found in the left ventricle. A decreased mRNA ratio of FKBP12.6 to RyR2 likely reflected dissociation of FKBP12.6 in cardiomyopathy. These changes were normalized by Dajisentan, comparable to propranolol.

CONCLUSION

Increased susceptibility to VF in l-thyroxin-induced cardiomyopathy is related to increase in diastolic Ca(2+) levels, resulting from downregulated FKBP12.6 and upregulated ET system. ET antagonism might be useful in settings of FKBP12.6 dissociation.

Thyroid hormone and blood pressure regulation

Thyroid hormone has well-recognized effects on the cardiovascular system and blood pressure regulation. Blood pressure is altered across the entire spectrum of thyroid disease. The effects of hyperthyroidism include increased cardiac output, contractility, tachycardia, widened pulse pressure, decreased systemic vascular resistance, and increased basal metabolic rate. The manifestations of hypothyroidism are in marked contrast to those of hyperthyroidism and include decreased cardiac output, narrow pulse pressure, increased systemic vascular resistance, and decreased metabolic rate. Although thyroid hormone affects almost all tissues of the body and mediates changes in homeostasis, adaptations of the cardiovascular system can result in changes in blood pressure to accommodate the new demands on the system. In this paper, we review the direct and indirect thyroid hormone-mediated effects on blood pressure.