The association of polymorphisms of ß-adrenergic receptors genes with the low triiodothyronine syndrome in patients with a heart failure.

The course of heart failure (HF) and its progression is associated with comorbidities, genetic factors and a dynamics of a number of biomarkers. The low triiodothyronine syndrome (LT3S) is observed in some patients with HF. Extremely little data are available in the literature regarding the effect of ß-adrenoreceptors (ß-AR) genes polymorphisms on the development of LT3S and many contradictory results about their association with HF course. This encourages new research in this area. AIM: The aim of study was to evaluate the relationship of ß-adrenergic receptors gene polymorphisms with low triiodothyronine syndrome in patients with a heart failure. MATERIALS AND METHODS: 354 patients with HF on a background of postinfarction cardiosclerosis were included to the study. At 89 (25.1%) patients LT3S was diagnosed. The course of HF was studied for 2 years. Mean levels of thyroid stimulating hormone (TSH), free T3f and T4f were evaluated. Genotyping of 4 single nucleotide polymorphisms (Gly389Arg of ß1-AR gene, Ser49Gly of ß1-AR gene, Gln27Glu of ß2- AR gene and Ser275 of GNß3 gene) was performed by polymerase chain reaction. Genetic and epidemiological analysis was performed using the SNPStats program. RESULTS: The risk of LT3S in patients with HF increases with homozygous G/G variant of Gln27Glu polymorphism of the ß2-AR gene (OR=2.21, p=0.037), described as a recessive model of inheritance. There was a tendency to increase the risk of LT3S development in the presence of the genotype C/T of the Ser275 polymorphism of the GNb3 gene (OR=1.75, p=0.054), described as an over-dominant model. The genotype C/G of the Gln27Glu polymorphism of the ß2-AR gene was associated with a decreased risk of LT3S development (OR=0.54, p=0.037), described as over-dominant model. Patients with HF carriers the A allele (A/GA/A) of the Ser49Gly polymorphism of the ß1-AR gene have a lower risk of repeated hospitalization due to HF decompensation (OR=0.50, p=0.032), described as a dominant model. There was a tendency to increase the risk of re-hospitalization in the G-allele (C/GG/ G) variant of the Gln27Glu polymorphism of the ß2-AR gene (OR=1.68, p=0.057), described as a dominant heredity model. At patients with HF in combination with LT3S the risk of re-hospitalization increases at C/G variant of the Gln27Glu polymorphism of ß2-AR gene (OR=1.25, p=0.025), described as an over-dominant model. CONCLUSIONS: The results suggest that congenital genetic alterations in ß-adrenergic pathways may be associated with the development of LT3S in patients with HF and the features of the HF course.

Thyroxine increases Serca2 and Ryr2 gene expression in heart failure rats with euthyroid sick syndrome

ABSTRACT Objective The current study was aimed at analyzing sarcoplasmic reticulum Ca2+ ATPase (Serca2) and ryanodine receptor type 2 (Ryr2) gene expression in rats subjected to surgery that induced HF and were subsequently treated with T4 using physiological doses. Materials and methods HF was induced in 18 male Wistar rats by clipping the ascending thoracic aorta to generate aortic stenosis (HFS group), while the control group (9-sham) underwent thoracotomy. After 21 weeks, the HFS group was subdivided into two subgroups. One group (9 Wistar rats) with HF received 1.0 µg of T4/100 g of body weight for five consecutive days (HFS/T4); the other group (9 Wistar rats) received isotonic saline solution (HFS/S). The animals were sacrificed after this treatment and examined for signs of HF. Samples from the left ventricles of these animals were analyzed by RT-qPCR for the expression of Serca2 and Ryr2 genes. Results Rats with HF developed euthyroid sick syndrome (ESS) and treatment with T4 restored the T3 values to the Sham level and increased Serca2 and Ryr2 gene expression, thereby demonstrating a possible benefit of T4 treatment for heart function in ESS associated with HF. Conclusion The T4 treatment can potentially normalize the levels of T3 as well elevated Serca2 and Ryr2 gene expression in the myocardium in heart failure rats with euthyroid sick syndrome.

Thyroxine increases Serca2 and Ryr2 gene expression in heart failure rats with euthyroid sick syndrome.

OBJECTIVE: The current study was aimed at analyzing sarcoplasmic reticulum Ca2+ ATPase (Serca2) and ryanodine receptor type 2 (Ryr2) gene expression in rats subjected to surgery that induced HF and were subsequently treated with T4 using physiological doses. MATERIALS AND METHODS: HF was induced in 18 male Wistar rats by clipping the ascending thoracic aorta to generate aortic stenosis (HFS group), while the control group (9-sham) underwent thoracotomy. After 21 weeks, the HFS group was subdivided into two subgroups. One group (9 Wistar rats) with HF received 1.0 µg of T4/100 g of body weight for five consecutive days (HFS/T4); the other group (9 Wistar rats) received isotonic saline solution (HFS/S). The animals were sacrificed after this treatment and examined for signs of HF. Samples from the left ventricles of these animals were analyzed by RT-qPCR for the expression of Serca2 and Ryr2 genes. RESULTS: Rats with HF developed euthyroid sick syndrome (ESS) and treatment with T4 restored the T3 values to the Sham level and increased Serca2 and Ryr2 gene expression, thereby demonstrating a possible benefit of T4 treatment for heart function in ESS associated with HF. CONCLUSION: The T4 treatment can potentially normalize the levels of T3 as well elevated Serca2 and Ryr2 gene expression in the myocardium in heart failure rats with euthyroid sick syndrome.

Astrocyte Elevated Gene-1 (AEG-1) Contributes to Non-thyroidal Illness Syndrome (NTIS) Associated with Hepatocellular Carcinoma (HCC).

Non-thyroidal illness syndrome (NTIS), characterized by low serum 3,5,3'-triiodothyronine (T3) with normal l-thyroxine (T4) levels, is associated with malignancy. Decreased activity of type I 5'-deiodinase (DIO1), which converts T4 to T3, contributes to NTIS. T3 binds to thyroid hormone receptor, which heterodimerizes with retinoid X receptor (RXR) and regulates transcription of target genes, such as DIO1. NF-κB activation by inflammatory cytokines inhibits DIO1 expression. The oncogene astrocyte elevated gene-1 (AEG-1) inhibits RXR-dependent transcription and activates NF-κB. Here, we interrogated the role of AEG-1 in NTIS in the context of hepatocellular carcinoma (HCC). T3-mediated gene regulation was analyzed in human HCC cells, with overexpression or knockdown of AEG-1, and primary hepatocytes from AEG-1 transgenic (Alb/AEG-1) and AEG-1 knock-out (AEG-1KO) mice. Serum T3 and T4 levels were checked in Alb/AEG-1 mice and human HCC patients. AEG-1 and DIO1 levels in human HCC samples were analyzed by immunohistochemistry. AEG-1 inhibited T3-mediated gene regulation in human HCC cells and mouse hepatocytes. AEG-1 overexpression repressed and AEG-1 knockdown induced DIO1 expression. An inverse correlation was observed between AEG-1 and DIO1 levels in human HCC patients. Low T3 with normal T4 was observed in the sera of HCC patients and Alb/AEG-1 mice. Inhibition of co-activator recruitment to RXR and activation of NF-κB were identified to play a role in AEG-1-mediated down-regulation of DIO1. AEG-1 thus might play a role in NTIS associated with HCC and other cancers.

Changes in the central component of the hypothalamus-pituitary-thyroid axis in a rabbit model of prolonged critical illness.

INTRODUCTION: Prolonged critically ill patients reveal low circulating thyroid hormone levels without a rise in thyroid stimulating hormone (TSH). This condition is labeled "low 3,5,3'-tri-iodothyronine (T3) syndrome" or "nonthyroidal illness syndrome (NTI)" or "euthyroid sick syndrome". Despite the low circulating and peripheral tissue thyroid hormone levels, thyrotropin releasing hormone (TRH) expression in the hypothalamus is reduced and it remains unclear which mechanism is responsible. We set out to study whether increased hypothalamic T3 availability could reflect local thyrotoxicosis and explain feedback inhibition-induced suppression of the TRH gene in the context of the low T3 syndrome in prolonged critical illness. METHODS: Healthy rabbits were compared with prolonged critically ill, parenterally fed animals. We visualized TRH mRNA in the hypothalamus by in situ-hybridization and measured mRNA levels for the type II iodothyronine diodinase (D2), the thyroid hormone transporters monocarboxylate transporter (MCT) 8, MCT10 and organic anion co-transporting polypeptide 1C1 (OATP1C1) and the thyroid hormone receptors alpha (TRalpha) and beta (TRbeta) in the hypothalamus. We also measured the activity of the D2 and type III iodothyronine deiodinase (D3) enzymes. RESULTS: In the hypothalamus of prolonged critically ill rabbits with low circulating T3 and TSH, we observed decreased TRH mRNA, increased D2 mRNA and increased MCT10 and OATP1C1 mRNA while MCT8 gene expression was unaltered as compared with healthy controls. This coincided with low hypothalamic thyroxine (T4) and low-normal T3 concentrations, without a change at the thyroid hormone receptor level. CONCLUSIONS: Although expression of D2 and of the thyroid hormone transporters MCT10 and OATP1C1 were increased in the hypothalamus of prolonged critical ill animals, hypothalamic T4 and T3 content or thyroid hormone receptor expression were not elevated. Hence, decreased TRH gene expression, and hereby low TSH and T3 during prolonged critical illness, is not exclusively brought about by hypothalamic thyrotoxicosis, and infer other TRH suppressing factors to play a role.

Expression of thyroid hormone transporters during critical illness.

OBJECTIVE: Prolonged critically ill patients have low circulating thyroid hormone (TH) levels without a rise in TSH, a condition labeled 'the low tri-iodothyronine (T(3)) syndrome'. Currently, it is not clear whether this represents an adaptive response. We examined the role of TH transporters monocarboxylate transporter 8 (MCT8, also known as SLC16A2) and MCT10 in the pathogenesis of the low T(3) syndrome in prolonged critical illness. METHODS: A clinical observational study in critically ill patients and an intervention study in an in vivo animal model of critical illness. Gene expression levels of MCT8 and MCT10 were measured by real-time PCR. RESULTS: In prolonged critically ill patients, we measured increased MCT8 but not MCT10 gene expression levels in liver and skeletal muscle as compared with patients undergoing acute surgical stress. In a rabbit model of prolonged critical illness, gene expression levels of MCT8 in liver and of MCT10 in skeletal muscle were increased as compared with healthy controls. Treatment of prolonged critically ill rabbits with TH (thyroxine+T(3)) resulted in a downregulation of gene expression levels of MCT8 in liver and of MCT10 in muscle. Transporter expression levels correlated inversely with circulating TH parameters. CONCLUSIONS: These data suggest that alterations in the expression of TH transporters do not play a major role in the pathogenesis of the 'low T(3) syndrome' but rather reflect a compensatory effort in response to hypothyroidism.

Hepatocyte 'priming' and increase in transforming growth factor-beta1 mRNA expression are delayed in hypothyroid versus euthyroid rats during liver regeneration.

Hypothyroidism decreases liver weight and delays the compensatory liver growth after partial hepatectomy (PH) as compared with the euthyroid condition. The aim of this study was to investigate, in hypothyroid rats, the mRNA expression of genes modulating these effects, focusing on c-fos and c-myc, hallmarks of hepatocyte 'priming', and on transforming growth factor-beta1 (TGF-beta1) and its receptor, the transforming growth factor-beta1 receptor-type II (TbetaR-II), negative regulators of liver growth. Euthyroid and hypothyroid male Wistar rats underwent 70% PH and total RNA was isolated from frozen liver samples removed at basal state and during regeneration, 0-144 h after surgery. In this study, we show for the first time that, in the basal liver state, hypothyroidism increased TGF-beta1 and TbetaR-II mRNA levels by 45% and 30%, respectively, as compared with the euthyroid condition and, after PH, resulted in a approximately 12-h delay in the activation of c-fos and c-myc mRNA expression. Moreover, the increase in TGF-beta1 mRNA levels, detected 24-48 h after PH in euthyroid rats, was delayed by 72 h in hypothyroid rats, occurring when a concomitant reduction in TbetaR-II was measured. These results suggest that, in hypothyroid rats, at the basal liver level, the increase in mRNA expression of genes that negatively regulate liver growth might be involved in the decrease in liver weight and that, after PH, the delay of hepatocyte 'priming' and coordinated changes in mRNA expression of negative regulators of liver regeneration might be involved in delaying the regenerative process.

Induction of type 1 iodothyronine deiodinase to prevent the nonthyroidal illness syndrome in mice.

Essentially all serious illness is associated with a decrease in circulating T(3), a condition known as the nonthyroidal illness syndrome. Substantial evidence suggests that a contributing factor to this syndrome is a cytokine-induced decrease in hepatic type 1 iodothyronine deiodinase (D1), an enzyme that converts T(4) to T(3). The type 1 deiodinase is induced at the transcriptional level by T(3), but illness-associated cytokines block this induction, resulting in decreased T(3) and hence a further decline in D1 expression. We demonstrated that IL-1 blocks the ability of T(3) to induce D1 in rat hepatocyte primary cultures and that forced expression of steroid receptor co- activator 1 (SRC-1) prevents this cytokine effect. This led us to test whether forced hepatic expression of SRC-1 can prevent the nonthyroidal illness syndrome in vivo. Pretreatment of endotoxin-treated mice with an adenovirus that expresses SRC-1, compared with a control adenovirus, prevented the endotoxin-induced decreases in hepatic D1 and plasma T(3). The data suggest that a cytokine-induced defect in T(3) receptor coactivators is an important component of this animal model of nonthyroidal illness and that the syndrome can be overcome by forced expression of the coactivator.

Low triiodothyronine (T3) or reverse triiodothyronine (rT3) syndrome modifies gene expression in rats with congestive heart failure.

Heart failure (HF) is frequently associated with euthyroid "sick" syndrome (low T3 and elevated rT3). We investigated if altered thyroid hormone in HF could affect expression of the TH receptor (TRalpha1), and alpha and beta myosin heavy chains (alpha-MHC, beta-MHC). HF was provoked in rats by aortic stenosis. We showed that rT3 generated from liver and kidney deiodination significantly increased and T3 decreased in HF; there was significantly higher TRalpha1 expression, no alpha-MHC expression, but beta-MHC expression. Changes in TRalpha could be compensating for low T3 from HF.

Regulation of hepatocyte thyroxine 5'-deiodinase by T3 and nuclear receptor coactivators as a model of the sick euthyroid syndrome.

The syndrome of nonthyroidal illness, also known as the sick euthyroid syndrome, is characterized by a low plasma T3 and an "inappropriately normal" plasma thyrotropin in the absence of intrinsic disease of the hypothalamic-pituitary-thyroid axis. The syndrome is due in part to decreased activity of type I iodothyronine 5'-deiodinase (5' D-I), the hepatic enzyme that converts thyroxine to T3 and that is induced at the transcriptional level by T3. The hypothesis tested is that cytokines decrease T3 induction of 5' D-I, resulting in decreased T3 production and hence a further decrease in 5' D-I. The proposed mechanism is competition for limiting amounts of nuclear receptor coactivators between the 5' D-I promoter and the promoters of cytokine-induced genes. Using primary cultures of rat hepatocytes, we demonstrate that interleukins 1 and 6 inhibit the T3 induction of 5' D-I RNA and enzyme activity. This effect is at the level of transcription and can be partially overcome by exogenous steroid receptor coactivator-1 (SRC-1). The physical mass of endogenous SRC-1 is not affected by cytokine exposure, and exogenous SRC-1 does not affect 5' D-I in the absence of cytokines. The data support the hypothesis that cytokine-induced competition for limiting amounts of coactivators decreases hepatic 5' D-I expression, contributing to the etiology of the sick euthyroid syndrome.

Diagnosis of thyroid hormone transport protein anomalies: an overview.

Inherited or acquired variations in the serum concentrations of TBG, TTR or albumin are rather common. Clinical studies have shown that most patients with transport protein variations were referred for thyroid testing because of incidentally detected "unusual" thyroid function tests. Although, usually no palpable thyroid abnormalities were found, the interpretation of these unexpected thyroid function tests resulted very often in inappropriate treatment with surgery, 131-iodine, antithyroid drugs as well as T4-replacement therapy. The clinical impact in the interpretation and diagnosis of thyroid hormone transport protein variations is to prevent these patients of unnecessary and sometimes also contraindicated treatment. If changes in thyroid hormone transport proteins in individuals with thyroid disorders or in individuals with the coexistence of two inherited defects are seen, difficulties in the interpretation of thyroid function tests will still occur.

Thyroid function and attention-deficit hyperactivity disorder.

OBJECTIVE: To examine thyroid indices in a community referred sample of boys with attention-deficit hyperactivity disorder (ADHD) for evidence of generalized resistance to thyroid hormone (GRTH). METHOD: TSH, T3, and T4 values were gathered prospectively in 53 physician, school, and/or parent referred ADHD subjects, and in 41 age and gender-matched normal controls. RESULTS: None were in the range suggestive of global or pituitary thyroid hormone resistance. CONCLUSIONS: GRTH is rare, and thyroid function should not be measured routinely in nonfamilial ADHD.

[Evaluating thyroid gland function in patients with protein anomalies]. / Beurteilung der Schilddrüsenfunktion bei Patienten mit Proteinanomalien.

The euthyroid hyperthyroxinemia (EHT) is characterized on the one hand by a normal basal THS or TRH-TSH response but also by high plasma values of total thyroxine (TT4) on the other. However if only TT4 is assessed, "hyperthyroidism" may be diagnosed erroneously. EHT may be caused by an increase of specific thyroxine binding proteins which may be hereditary (permanent) or acquired (transient). The most frequent disturbance is due to an estrogen induced increase of thyroxine binding globulin (TBG) in the course of pregnancy, anticonceptive drugs or estrogen treatment. The albumin associated HT (FDH syndrome), first reported in 1979, has autosomal dominant traits. 144 patients with FDH syndrome were observed during the period between 1984 and 1990, i.e. 7% (1986) of all hyperthyroid patients explored. Family screening is required to prevent unjustified treatment. Additionally existing disturbances of thyroid function as well as other protein binding anomalies may both cause problems in differential diagnosis. Prealbumin associated hyperthyroxinemia (PAAH), first published in 1982, may be due to an inherited increase in affinity, but may also be the consequence of a true elevation of prealbumin plasma concentration in the course of an islet cell cancer; both conditions are extremely rare. Nearly as rare are patients with plasma autoantibodies directed against T4 and/or T3 (5 cases); yet, a reverse T3 autoantibody could be observed in merely 1 case. By means of our modified radio-thyroxine-agarosegel-iceelectrophoresis all such protein anomalies may be diagnosed and differentiated in 1 procedure. Moreover, all other types of EHT must be taken into consideration by differential diagnosis.

Elevated thyroxine and free thyroxine in euthyroid patients: familial dysalbuminemic hyperthyroxinemia.

An eleven year old male was evaluated because of persistent elevation of thyroxine levels and elevated thyroxine index calculated as "T7" but normal thyrotropin levels. The findings were demonstrated by thyroxine binding protein electrophoresis to be due to aberrant thyroxine binding to albumin. The abnormality was also documented in the patient's father. This entity, known as familial dysalbuminemic hyperthyroxinemia, is being reported with increasing frequency and should be suspected when elevated total thyroxine and free thyroxine or "T7" levels are associated with a normal thyrotropin level. The case reported is somewhat unusual in that the triiodothyronine affinity of the aberrant protein appears to be more pronounced than usually reported with this syndrome and the corresponding total triiodothyronine level was significantly elevated.

Thyroid hormone receptor expression in the "sick euthyroid" syndrome.

To explore the hypothesis that alteration of T3 receptor expression may be an important mechanism controlling the tissue effects of thyroid hormones in the "sick euthyroid" syndrome, specific triiodothyronine (T3) receptor mRNAs were measured in tissues from normal subjects and from patients with liver disease, chronic renal failure, or with multiple organ failure on an intensive care unit (ICU). In all patient groups circulating free thyroxine and free T3 were reduced, while thyroid stimulating hormone remained normal. In patients with liver or renal disease, there were significant increases in levels of both alpha and beta T3 receptor mRNAs in peripheral mononuclear cells (PMNCs); in ICU patients there was a significant increase in beta mRNA. In patients with liver disease increases in T3 receptor mRNAs were not confined to PMNCs but were also found in liver biopsy specimens when levels were compared with those in normal donor liver. After liver transplantation, receptor mRNAs in PMNCs were similar to those in controls; likewise beta mRNA was similar in liver tissue to normal liver. There was, however, persistent elevation in alpha receptor mRNA. Increases in T3 receptor expression in non-thyroidal illness may be responsible for the maintenance of euthyroidism in the face of reduced levels of circulating thyroid hormones.

Familial dysalbuminemic hyperthyroxinemia associated with primary thyroid disease.

This study describes a family with intrinsic thyroid disease in addition to familial dysalbuminemic hyperthyroxinemia, a syndrome associated with euthyroidism and increased binding of thyroxine to serum albumin. The simultaneous occurrence of thyroid disease and elevated serum thyroxine concentrations due to familial dysalbuminemic hyperthyroxinemia may confound the diagnosis of the two concurrent disorders and the subsequent therapy of the thyroid disease.