Metabolic Effects of the Intracellular Regulation of Thyroid Hormone: Old Players, New Concepts

Marked differences in thyroxine (T4) metabolism following in vitro exposure of Wistar rat and human hepatocytes to several reference CAR/PXR nuclear receptor activators

Our study builds upon previous findings (Baze et al., 2024) by investigating species differences in thyroxine (T4) metabolism regulation by CAR/PXR activators using cryopreserved primary Wistar rat hepatocytes (PRH) and human hepatocytes (PHH) in 2D-sandwich over a 7-day treatment period. Daily exposure of PRH to phenobarbital, 5-Pregnen-3β-ol-20-one-16α‑carbonitrile (PCN) or dexamethasone increased T4 clearance over the last 24 h exposure (up to 60 %, 79 % and 67 % over control, respectively) and secretion of T4-glucuronide (T4-G; up to 463, 661 and 545 pmol/106 cells over control, respectively). Effects were concentration-dependent for phenobarbital and PCN and highest at the lowest concentration for dexamethasone, while rifampicin barely affected T4 clearance and T4-G secretion. None of the compounds, at any tested concentration, affected these parameters in PHH. Additionally, mRNA expression data were consistent with the species-specific and concentration-dependent regulation of phase I Cyp/CYP, phase II Ugt/UGT and phase III Mrp2/MRP2 pathways occurring in rat and human liver following CAR/PXR activation. T4-UGT relative activity increased in PRH only, specifically by PCN, dexamethasone and phenobarbital. The comparison of PRH and PHH responses to compounds represents an important step towards using in vitro methods to reduce animal testing. We recommend using relative T4-UGT activity thresholds observed in PRH as benchmarks for defining compound-related effects across species, helping determine the human relevance of thyroid effects in rodents.

Unveiling the Role of Selenium in Child Development: Impacts on Growth, Neurodevelopment and Immunity

Selenium (Se) is a vital trace element for children, playing a crucial role in numerous physiological processes, including antioxidant defense, immune regulation, thyroid function, and bone metabolism. Emerging evidence highlights its potential impact on child development and growth while also underscoring the complexity of its mechanisms and the global variations in Se intake. The aim of this review is to comprehensively elucidate the significance of Se in various biological processes within the human body, with a focus on its role in child development and growth; its biochemical effects on the nervous system, thyroid function, immune system, and bone tissue; and the implications of Se deficiency and toxicity. This review integrates findings from experimental models, epidemiological studies, and clinical trials to explore Se's role in neurodevelopment, growth regulation, and immune competence in children. Selenoproteins, which regulate oxidative stress and thyroid hormone and bone metabolism, are essential for normal growth and cognitive development in children. Se deficiency and toxicity has been linked to impaired immune function, growth retardation, and decreased immune function. The findings underscore Se's influence on various biological pathways that are critical for healthy child development and its broader importance for child health. Public health strategies aimed at optimizing selenium intake may play a pivotal role in improving pediatric health outcomes worldwide.

Leptin enhances the intracellular thyroid hormone activation in skeletal muscle to boost energy balance

Thyroid hormones (THs) are key modulators of energy metabolism and cross-talk with other endocrine and metabolic factors. Notably, leptin can increase hypothalamic control of TH synthesis as an adaptive metabolic response regulating body weight. In this study, we found that the TH signal is heightened in overweight humans and is lost with obesity. In mice, systemic and intracerebroventricular leptin injection induces the expression of type 2 deiodinase (D2), the TH-activating enzyme, in skeletal muscle. Mechanistically, leptin enhances the transcription of D2 by a STAT3- and α-melanocyte-stimulating hormone (α-MSH)/cyclic AMP (cAMP)-dependent regulation. Notably, mice lacking D2 or with a mutation in the TH receptor do not exhibit the metabolic effects of leptin, such as increased insulin sensitivity and oxygen consumption, indicating that leptin's peripheral metabolic effects in skeletal muscle are mediated by TH. These findings underscore the critical role of leptin in integrating the TH-induced metabolic activation, while also contributing to appetite suppression in response to perceived fat stores.

Nonanoic acid and cholecystokinin induce beige adipogenesis

Beige adipocytes, crucial for thermogenesis, offer a potential therapeutic strategy for obesity. This study investigated the anti-obesity effects of nonanoic acid (NoA), medium-chain fatty acids, and cholecystokinin-8 (CCK-8) on beige adipogenesis in C3H10T1/2 mesenchymal stem cells (C3H10T1/2 MSCs). We observed a significant increase in cholecystokinin B receptor expression in beige adipocytes compared to preadipocytes. The co-treatment with NoA and CCK-8 enhanced beige adipocyte differentiation and lipid accumulation. Moreover, the co-treatment with NoA and CCK-8 upregulated the mRNA expression of thermogenic genes and increased mitochondrial activity more effectively than individual treatment. Specifically, NoA and CCK-8 co-treatment also elevated the protein expression of uncoupling protein 1 and peroxisome proliferator-activated receptor-gamma coactivator-1 alpha. These findings suggest that the additive effect of NoA and CCK-8 promotes the beiging/browning of body fat in beige adipogenesis, potentially serving as an effective approach in the prevention and treatment of obesity and insulin resistance.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-024-01699-6.

Reproductive and Metabolic Health Following Exposure to Environmental Chemicals: Mechanistic Insights from Mammalian Models

The decline in human reproductive and metabolic health over the past 50 years is associated with exposure to complex mixtures of anthropogenic environmental chemicals (ECs). Real-life EC exposure has varied over time and differs across geographical locations. Health-related issues include declining sperm quality, advanced puberty onset, premature ovarian insufficiency, cancer, obesity, and metabolic syndrome. Prospective animal studies with individual and limited EC mixtures support these observations and provide a means to investigate underlying physiological and molecular mechanisms. The greatest impacts of EC exposure are through programming of the developing embryo and/or fetus, with additional placental effects reported in eutherian mammals. Single-chemical effects and mechanistic studies, including transgenerational epigenetic inheritance, have been undertaken in rodents. Important translational models of human exposure are provided by companion animals, due to a shared environment, and sheep exposed to anthropogenic chemical mixtures present in pastures treated with sewage sludge (biosolids). Future animal research should prioritize EC mixtures that extend beyond a single developmental stage and/or generation. This would provide a more representative platform to investigate genetic and underlying mechanisms that explain sexually dimorphic and individual effects that could facilitate mitigation strategies.

ZNF169 promotes thyroid cancer progression via upregulating FBXW10

BACKGROUND

Zinc finger protein 169 (ZNF169) plays a key role in cancer development. However, the specific role of ZNF169 in the tumorigenesis of thyroid carcinoma (THCA) remains poorly understood.

METHODS

The expression of ZNF169 was measured using immunohistochemistry, RT-qPCR, and western blot. Cell proliferation was detected using CCK-8 assay and cell colony formation assays, while cell migration was determined by Transwell assay. Flow cytometry was used to detect cell apoptosis and cell cycle distribution. The interaction of ZNF169 and its downstream gene was studied using luciferase assay and CHIP-PCR. Recovery assay in cells and animals were also performed to demonstrate the mechanism.

RESULTS

ZNF169 was highly expressed in THCA tissues and cells lines compared with matched adjacent non-cancerous thyroid tissues or normal thyroid epithelial cell. Moreover, thyroid cancer cell proliferation and migration were suppressed following ZNF169 knockdown, while were potentiated by ZNF169 overexpression. ZNF169 also regulate THCA cell apoptosis and cell cycle progression. Mechanically, ZNF169 enhanced the transcription activity and expression of F-box/WD repeat-containing protein 10 (FBXW10) via the binding to its promoter. There was a positive correlation between ZNF169 and FBXW10 in THCA patients. In addition, knockdown of FBXW10 suppressed the proliferation of THCA cells. Recovery assays in vitro and in vivo demonstrated that FBXW10 knockdown reversed the effects of ZNF169 overexpression on THCA cell proliferation and tumor growth.

CONCLUSIONS

In summary, ZNF169 promotes THCA progression via upregulation of FBXW10, which may provide a novel theoretical basis for the development of clinical therapies for THCA.

Global metabolomic alterations associated with endocrine-disrupting chemicals among pregnant individuals and newborns

BACKGROUND

Gestational exposure to non-persistent endocrine-disrupting chemicals (EDCs) may be associated with adverse pregnancy outcomes. While many EDCs affect the endocrine system, their effects on endocrine-related metabolic pathways remain unclear. This study aims to explore the global metabolome changes associated with EDC biomarkers at delivery.

METHODS

This study included 75 pregnant individuals who delivered at the University of Cincinnati Hospital from 2014 to 2017. We measured maternal urinary biomarkers of paraben/phenol (12), phthalate (13), and phthalate replacements (4) from the samples collected during the delivery visit. Global serum metabolome profiles were analyzed from maternal blood (n = 72) and newborn (n = 63) cord blood samples collected at delivery. Fifteen of the 29 urinary biomarkers were excluded due to low detection frequency or potential exposures during hospital stay. We assessed metabolome-wide associations between 14 maternal urinary biomarkers and maternal/newborn metabolome profiles. Additionally, performed enrichment analysis to identify potential alterations in metabolic pathways.

RESULTS

We observed metabolome-wide associations between maternal urinary concentrations of phthalate metabolites (mono-isobutyl phthalate), phthalate replacements (mono-2-ethyl-5-carboxypentyl terephthalate, mono-2-ethyl-5-hydroxyhexyl terephthalate) and phenols (bisphenol-A, bisphenol-S) and maternal serum metabolome, using q-value < 0.2 as a threshold. Additionally, associations of phthalate metabolites (mono-n-butyl phthalate, monobenzyl phthalate) and phenols (2,5-dichlorophenol, BPA) with the newborn metabolome were noted. Enrichment analyses revealed associations (p-gamma < 0.05) with amino acid, carbohydrate, lipid, glycan, vitamin, and other cofactor metabolism pathways.

CONCLUSION

Maternal paraben, phenol, phthalate, and phthalate replacement biomarker concentrations at delivery were associated with maternal and newborn serum global metabolome.

Muscle PGC-1α Overexpression Drives Metabolite Secretion Boosting Subcutaneous Adipocyte Browning

Muscle and adipose tissue (AT) are in mutual interaction through the integration of endocrine and biochemical signals, thus regulating whole-body function and physiology. Besides a traditional view of endocrine relationships that imply the release of cytokines and growth factors, it is becoming increasingly clear that a metabolic network involving metabolites as signal molecules also exists between the two tissues. By elevating the number and functionality of mitochondria, a key role in muscle metabolism is played by the master regulator of mitochondrial biogenesis peroxisome-proliferator-activated receptor-γ coactivator-1α (PGC-1α), that induces a fiber type shift from glycolytic to oxidative myofibers. As a consequence, the upregulation of muscle respiratory rate might affect metabolite production and consumption. However, the underlying mechanisms have not yet been fully elucidated. Here, we used a muscle-specific PGC-1α overexpressing mouse model (MCK-PGC-1α) to analyze the metabolite secretion profile of serum and culture medium recovered from MCK-PGC-1α muscle fibers by NMR. We revealed modified levels of different metabolites that might be ascribed to the metabolic activation of the skeletal muscle fibers. Notably, the dysregulated levels of these metabolites affected adipocyte differentiation, as well as the browning process in vitro and in vivo. Interestingly such effect was exacerbated in the subcutaneous WAT, while only barely present in the visceral WAT. Our data confirm a prominent role of PGC-1α as a trigger of mitochondrial function in skeletal muscle and propose a novel function of this master regulator gene in modulating the metabolite production in turn affecting the activation of WAT and its conversion toward the browning.

The Downregulation of the Liver Lipid Metabolism Induced by Hypothyroidism in Male Mice: Metabolic Flexibility Favors Compensatory Mechanisms in White Adipose Tissue

In mammals, the maintenance of energy homeostasis relies on complex mechanisms requiring tight synchronization between peripheral organs and the brain. Thyroid hormones (THs), through their pleiotropic actions, play a central role in these regulations. Hypothyroidism, which is characterized by low circulating TH levels, slows down the metabolism, which leads to a reduction in energy expenditure as well as in lipid and glucose metabolism. The objective of this study was to evaluate whether the metabolic deregulations induced by hypothyroidism could be avoided through regulatory mechanisms involved in metabolic flexibility. To this end, the response to induced hypothyroidism was compared in males from two mouse strains, the wild-derived WSB/EiJ mouse strain characterized by a diet-induced obesity (DIO) resistance due to its high metabolic flexibility phenotype and C57BL/6J mice, which are prone to DIO. The results show that propylthiouracil (PTU)-induced hypothyroidism led to metabolic deregulations, particularly a reduction in hepatic lipid synthesis in both strains. Furthermore, in contrast to the C57BL/6J mice, the WSB/EiJ mice were resistant to the metabolic dysregulations induced by hypothyroidism, mainly through enhanced lipid metabolism in their adipose tissue. Indeed, WSB/EiJ mice compensated for the decrease in hepatic lipid synthesis by mobilizing lipid reserves from white adipose tissue. Gene expression analysis revealed that hypothyroidism stimulated the hypothalamic orexigenic circuit in both strains, but there was unchanged melanocortin 4 receptor (Mc4r) and leptin receptor (LepR) expression in the hypothyroid WSB/EiJ mice strain, which reflects their adaptability to maintain their body weight, in contrast to C57BL/6J mice. Thus, this study showed that WSB/EiJ male mice displayed a resistance to the metabolic dysregulations induced by hypothyroidism through compensatory mechanisms. This highlights the importance of metabolic flexibility in the ability to adapt to disturbed circulating TH levels.

Ameliorative effect of ferulic acid on thyroid dysfunction against propyl-thiouracil induced hypothyroid rats

PURPOSE

Hypothyroidism is an endocrine disorder characterised by decreased T3, T4 and increased TSH levels. This study aims to examine the potential effects of Ferulic acid (FA) on rats with hypothyroidism induced by propylthiouracil through the estimation of biochemical parameters and histopathological studies.

METHODS

Twenty-five female wistar rats were allocated into five groups: Control group [1% CMC, p.o.], Disease group [PTU-50 mg/kg, p.o.], [Levothyroxine (LT4) group - 20 µg/kg, p.o. + PTU-50 mg/kg, p.o.], [FA -25 mg/kg, p.o. + PTU-50 mg/kg, p.o.] and [FA 50 mg/kg, p.o. + PTU-50 mg/kg, p.o.]. On 15th day blood was collected and serum was separated for estimation of biochemical parameters, liver and kidney homogenate was utilised for the estimation of oxidative stress markers and the thyroid gland was dissected to examine histological features.

RESULTS

PTU administration for 14 days showed a substantial decline in T3 and T4 and increases in TSH levels. PTU-administered rats significantly increased TC, TG and LDL levels, and decreased HDL levels. AST, ALT, urea, creatinine, and IL-6 were determined and these levels were significantly altered in PTU-induced hypothyroid group. In hypothyroid rats MDA, NO, GSH and SOD levels were significantly altered. However, treatment with FA for 14 days attenuated PTU-induced alterations. Furthermore, FA improves the histological changes of the thyroid gland.

CONCLUSION

In conclusion, FA treatment showed a protective effect against hypothyroidism by stimulating the thyroid hormones through the activation of thyroid peroxidase enzyme and improving thyroid function. In addition, FA diminished the increase in lipids, liver and kidney markers, oxidative stress and inflammation.

Relationship between serum thyroid hormone and interleukin-1b levels and postmortem tissue deiodinase activity in critically ill patients

Background

This study investigated the relationship between serum thyroid hormones and interleukin-1b (IL-1β) levels and postmortem tissue deiodinase activity in critically ill patients.

Methods

Serum thyroid hormones and IL-1β were measured on the 5th, 15th, and last day of 80 critically ill patients. Forty of these patients were non-survived, and liver and skeletal muscle were harvested to analyze type 1, 2, and 3 iodothyronine deiodinases (D1, D2, and D3) activity.

The selenoenzyme type I iodothyronine deiodinase: a new tumor suppressor in ovarian cancer

The selenoenzyme type I iodothyronine deiodinase (DIO1) catalyzes removal of iodine atoms from thyroid hormones. Although DIO1 action is reported to be disturbed in several malignancies, no work has been conducted in high-grade serous ovarian carcinoma (HGSOC), the most lethal gynecologic cancer. We studied DIO1 expression in HGSOC patients [The Cancer Genome Atlas (TCGA) data and tumor tissues], human cell lines (ES-2 and Kuramochi), normal Chinese hamster ovarian cells (CHO-K1), and normal human fallopian tube cells (FT282 and FT109). To study its functional role, DIO1 was overexpressed, inhibited [by propylthiouracil (PTU)], or knocked down (KD), and cell count, proliferation, apoptosis, cell viability, and proteomics analysis were performed. Lower DIO1 levels were observed in HGSOC compared to normal cells and tissues. TCGA analyses confirmed that low DIO1 mRNA expression correlated with worse survival and therapy resistance in patients. Silencing or inhibiting the enzyme led to enhanced ovarian cancer proliferation, while an opposite effect was shown following DIO1 ectopic expression. Proteomics analysis in DIO1-KD cells revealed global changes in proteins that facilitate tumor metabolism and progression. In conclusion, DIO1 expression and ovarian cancer progression are inversely correlated, highlighting a tumor suppressive role for this enzyme and its potential use as a biomarker in this disease.

The Role of Laser and Microwave in Treatment of Endocrine Disorders: A Systematic Review

Introduction: The treatment of endocrine problems like thyroid disease, diabetes mellitus (DM), and polycystic ovary syndrome (PCOS) faces significant challenges so that medical professionals worldwide try to find a new therapeutic approach. However, along with common treatments which include medications, hormone replacement therapy, and surgery; there is a growing interest in alternative therapies like laser therapy, which offers a non-invasive and unique technique for treating endocrine disorders alone or in combination with traditional methods. The main goal of this review was to do a systematic review on the role of the laser and Microwave in the treatment endocrine disorders. Methods: In the present systematic review, the most important databases, including PubMed, Scopus and Google Scholar, were searched for the studies examining the effect of lasers on the treatment of endocrine problems by using appropriate keywords and specific strategies from 1995 to 2023. All the studies that were not about lasers and endocrine were excluded. Results: Based on 51 reviewed studies, lasers and radiofrequency ablation such as RFA are effective in the treatment of thyroid diseases, hyperparathyroidism, pancreatic disorders, and sexual dysfunctions. Laser-induced interstitial thermal therapy (LITT) and microwave ablation (MWA) are genuine minimally invasive methods for the treatment of benign nodules, adenomas, and tumor ablation including pancreatic carcinomas and adrenal tumors. Intravenous laser blood irradiation (ILBI) which uses red, UV, and blue light could be effective in treating various metabolic disorders, such as DM. Conclusion: Laser as a cutting-edge and minimally invasive approach could treat various endocrine disorders. It has a great potential to treat and regulate hormonal imbalances, decrease inflammation, and relieve symptoms of various ailments, such as endocrine disorders.

The key roles of thyroid hormone in mitochondrial regulation, at interface of human health and disease

Mitochondria are highly plastic and dynamic organelles long known as the powerhouse of cellular bioenergetics, but also endowed with a critical role in stress responses and homeostasis maintenance, supporting and integrating activities across multifaced cellular processes. As a such, mitochondria dysfunctions are leading causes of a wide range of diseases and pathologies. Thyroid hormones (THs) are endocrine regulators of cellular metabolism, regulating intracellular nutrients fueling of sugars, amino acids and fatty acids. For instance, THs regulate the balance between the anabolism and catabolism of all the macro-molecules, influencing energy homeostasis during different nutritional conditions. Noteworthy, not only most of the TH-dependent metabolic modulations act via the mitochondria, but also THs have been proved to regulate the mitochondrial biosynthesis, dynamics and function. The significance of such an interplay is different in the context of specific tissues and strongly impacts on cellular homeostasis. Thus, a comprehensive understanding of THs-dependent mitochondrial functions and dynamics is required to develop more precise strategies for targeting mitochondrial function. Herein, we describe the mechanisms of TH-dependent metabolic regulation with a focus on mitochondrial action, in different tissue contexts, thus providing new insights for targeted modulation of mitochondrial dynamics.

Effects of thyroid hormones in skeletal muscle protein turnover

Thyroid hormones (THs) are critical regulators of muscle metabolism in both healthy and unhealthy conditions. Acting concurrently as powerful anabolic and catabolic factors, THs are endowed with a vital role in muscle mass maintenance. As a result, thyroid dysfunctions are the leading cause of a wide range of muscle pathologies, globally identified as myopathies. Whether muscle wasting is a common feature in patients with hyperthyroidism and is mainly caused by THs-dependent stimulation of muscle proteolysis, also muscle growth is often associated with hyperthyroid conditions, linked to THs-dependent stimulation of muscle protein synthesis. Noteworthy, also hypothyroid status negatively impacts on muscle physiology, causing muscle weakness and fatigue. Most of these symptoms are due to altered balance between muscle protein synthesis and breakdown. Thus, a comprehensive understanding of THs-dependent skeletal muscle protein turnover might facilitate the management of physical discomfort or weakness in conditions of thyroid disease. Herein, we describe the molecular mechanisms underlying the THs-dependent alteration of skeletal muscle structure and function associated with muscle atrophy and hypertrophy, thus providing new insights for targeted modulation of skeletal muscle dynamics.

Understanding the Roles of Selenium on Thyroid Hormone-Induced Thermogenesis in Adipose Tissue

Brown adipose tissue (BAT) and white adipose tissue (WAT) are known to regulate lipid metabolism. A lower amount of BAT compared to WAT, along with adipose tissue dysfunction, can result in obesity. Studies have shown that selenium supplementation protects against adipocyte dysfunction, decreases WAT triglycerides, and increases BAT triiodothyronine (T3). In this review, we discuss the relationship between selenium and lipid metabolism regulation through selenoprotein deiodinases and the role of deiodinases and thyroid hormones in the induction of adipose tissue thermogenesis. Upon 22 studies included in our review, we found that studies investigating the relationship between selenium and deiodinases demonstrated that selenium supplementation affects the iodothyronine deiodinase 2 (DIO2) protein and the expression of its associated gene, DIO2, proportionally. However, its effect on DIO1 is inconsistent while its effect on DIO3 activity is not detected. Studies have shown that the activity of deiodinases especially DIO2 protein and DIO2 gene expression is increased along with other browning markers upon white adipose tissue browning induction. Studies showed that thermogenesis is stimulated by the thyroid hormone T3 as its activity is correlated to the expression of other thermogenesis markers. A proposed mechanism of thermogenesis induction in selenium supplementation is by autophagy control. However, more studies are needed to establish the role of T3 and autophagy in adipose tissue thermogenesis, especially, since some studies have shown that thermogenesis can function even when T3 activity is lacking and studies related to autophagy in adipose tissue thermogenesis have contradictory results.

Are resting metabolic rate and clinical symptoms affected by variation of serum thyroid stimulating hormone levels within the normal range in healthy and women with hypothyroidism? A case-control study

BACKGROUND

It is unclear whether variation in thyroid stimulating hormone (TSH) levels within the reference range affect energy expenditure and clinical symptoms and even within the normal range of TSH levels, resting energy expenditure may alter. The aim of the present study was to determine whether treated hypothyroid subjects and healthy subjects with a low-normal TSH range (0.3-2.3 mIU/L) have better clinical outcomes and increased energy expenditure than those with a high-normal TSH range (2.3-4.3 mIU/L).

METHODS

This was a case-control study of 160 overweight/obese women with TSH levels across the reference range of 0.3-4.3 mU/l. Subjects were paired in four groups: healthy subjects with low-normal target TSH (n = 40), healthy subjects with high-normal target TSH (n = 40), subjects with treated hypothyroidism with low-normal target TSH (n = 40), and subjects with treated hypothyroidism with high-normal target TSH (n = 40). Resting energy expenditure (RMR), dietary intake, body composition, physical activity, and biochemical markers were assessed.

RESULTS

Subjects with low-normal (≤2.3 mU/L) and high-normal (>2.3 mU/L) TSH levels did not differ in terms of RMR, serum T3 levels, and clinical symptoms except fatigue (P = 0.013). However, serum fT4 levels were found to be significantly different between the study groups (P = 0.002). Serum fT4 concentration was the highest in subjects with treated hypothyroidism with low-normal target TSH.

CONCLUSION

Variation in serum TSH levels within the reference range did not significantly affect REE and clinical symptoms except fatigue in healthy and women with hypothyroidism.

Quantitative or qualitative biomolecular changes in blood serum composition induced by childhood obesity: A Fourier transform infrared examination

Childhood obesity (CO) negatively affects one in three children and stands as the fourth most common risk factor of health and well-being. Clarifying the molecular and structural modifications that transpire during the development of obesity is crucial for understanding its progression and devising effective therapies. The study was indeed conducted as part of an ongoing CO treatment trial, where data were collected from children diagnosed with CO before the initiation of non-drug treatment interventions. Our primary aim was to analyze the biochemical changes associated with childhood obesity, specifically focusing on concentrations of lipids, lipoproteins, insulin, and glucose. By comparing these parameters between the CO group (n = 60) and a control group of healthy children (n = 43), we sought to elucidate the metabolic differences present in individuals with CO. Our biochemical analyses unveiled lower LDL (low-density lipoproteins) levels and higher HDL (high-density lipoproteins), cholesterol, triglycerides, insulin, and glucose levels in CO individuals compared to controls. To scrutinize these changes in more detail, we employed Fourier transform infrared (FTIR) spectroscopy on the serum samples. Our results indicated elevated levels of lipids and proteins in the serum of CO, compared to controls. Additionally, we noted structural changes in the vibrations of glucose, β-sheet, and lipids in CO group. The FTIR technique, coupled with principal component analysis (PCA), demonstrated a marked differentiation between CO and controls, particularly in the FTIR region corresponding to amide and lipids. The Pearson test revealed a stronger correlation between biochemical data and FTIR spectra than between 2nd derivative FTIR spectra. Overall, our study provides valuable insights into the molecular and structural changes occurring in CO.

Biochemical Significance of miR-155 and miR-375 as Diagnostic Biomarkers and Their Correlation with the NF-κβ/TNF-α Axis in Breast Cancer

Serum microRNAs (miRs) have recently been proposed as potential cancer biomarkers for early detection. Thyroid hormones play a crucial role in human health, and their alterations are linked to a range of diseases, such as breast cancer. The relationship between NF-κβ, TNF-α, and non-coding RNAs is an urgent need for clinical trials. This study aimed to investigate serum expression folds of miR-155 and miR-375 and their correlations with NF-κβ and TNF-α in breast cancer patients. The current study was conducted on 183 unrelated female participants. Serum levels of free T3 and T4, as well as expression folds of miR-155 and miR-375, were significantly higher in patients with fibroadenoma and breast cancer, despite TSH being significantly lower. Additionally, the signaling of TNF-alpha and NF-κβ were found to be significantly upregulated in the serum of patients with breast cancer. Up-regulation of miR-155 and miR-375 expression may be diagnostic biomarkers of breast cancer, pointing to the role of NF-κβ and TNF-α expression in miR-155 and miR-375 expression as therapeutic targets of breast cancer in the future.

The ecological function of thyroid hormones

Thyroid hormones (TH) are central hormonal regulators, orchestrating gene expression and complex biological processes vital for growth and reproduction in variable environments by triggering specific developmental processes in response to external cues. TH serve distinct roles in different species: inducing metamorphosis in amphibians or teleost fishes, governing metabolic processes in mammals, and acting as effectors of seasonality. These multifaceted roles raise questions about the underlying mechanisms of TH action. Recent evidence suggests a shared ecological role of TH across vertebrates, potentially extending to a significant portion of bilaterian species. According to this model, TH ensure that ontogenetic transitions align with environmental conditions, particularly in terms of energy expenditure, helping animals to match their ontogenetic transition with available resources. This alignment spans post-embryonic developmental transitions common to all vertebrates and more subtle adjustments during seasonal changes. The underlying logic of TH function is to synchronize transitions with the environment. This review briefly outlines the fundamental mechanisms of thyroid signalling and shows various ways in which animals use this hormonal system in natural environments. Lastly, we propose a model linking TH signalling, environmental conditions, ontogenetic trajectory and metabolism. This article is part of the theme issue 'Endocrine responses to environmental variation: conceptual approaches and recent developments'.

To Be Frail or Not to Be Frail: This Is the Question-A Critical Narrative Review of Frailty

Many factors have contributed to rendering frailty an emerging, relevant, and very popular concept. First, many pandemics that have affected humanity in history, including COVID-19, most recently, have had more severe effects on frail people compared to non-frail ones. Second, the increase in human life expectancy observed in many developed countries, including Italy has led to a rise in the percentage of the older population that is more likely to be frail, which is why frailty is much a more common concern among geriatricians compared to other the various health-care professionals. Third, the stratification of people according to the occurrence and the degree of frailty allows healthcare decision makers to adequately plan for the allocation of available human professional and economic resources. Since frailty is considered to be fully preventable, there are relevant consequences in terms of potential benefits both in terms of the clinical outcome and healthcare costs. Frailty is becoming a popular, pervasive, and almost omnipresent concept in many different contexts, including clinical medicine, physical health, lifestyle behavior, mental health, health policy, and socio-economic planning sciences. The emergence of the new "science of frailty" has been recently acknowledged. However, there is still debate on the exact definition of frailty, the pathogenic mechanisms involved, the most appropriate method to assess frailty, and consequently, who should be considered frail. This narrative review aims to analyze frailty from many different aspects and points of view, with a special focus on the proposed pathogenic mechanisms, the various factors that have been considered in the assessment of frailty, and the emerging role of biomarkers in the early recognition of frailty, particularly on the role of mitochondria. According to the extensive literature on this topic, it is clear that frailty is a very complex syndrome, involving many different domains and affecting multiple physiological systems. Therefore, its management should be directed towards a comprehensive and multifaceted holistic approach and a personalized intervention strategy to slow down its progression or even to completely reverse the course of this condition.

Effects of Thyroid Powder on Tadpole (Lithobates catesbeiana) Metamorphosis and Growth: The Role of Lipid Metabolism and Gut Microbiota

A low metamorphosis rate of amphibian larvae, commonly known as tadpoles, limits the farming production of bullfrogs (Lithobates catesbeiana). This study aimed to examine the effects of processed thyroid powder as a feed additive on tadpole metamorphosis, lipid metabolism, and gut microbiota. Five groups of tadpoles were fed with diets containing 0 g/kg (TH0), 1.5 g/kg (TH1.5), 3 g/kg (TH3), 4.5 g/kg (TH4.5), and 6 g/kg (TH6) thyroid powder for 70 days. The results showed that TH increased the average weight of tadpoles during metamorphosis, with the TH6 group having the highest values. The TH4.5 group had the highest metamorphosis rate (p < 0.05). Biochemical tests and Oil Red O staining showed that the lipid (triglyceride) content in the liver decreased after TH supplementation, especially at doses higher than 1.5 g/kg. RT-qPCR revealed that TH at doses higher than 4.5 g/kg significantly up-regulated the transcriptional expression of the pparα, accb, fas, fadd6, acadl, and lcat genes, which are related to lipid metabolism (p < 0.05). These results showed that TH seems to simultaneously promote the synthesis and decomposition of lipid and fatty acids, but ultimately show a decrease in lipids. As for the gut microbiota, it is noteworthy that Verrucomicrobia increased significantly in the TH4.5 and TH6 groups, and the Akkermansia (classified as Verrucomicrobia) was the corresponding genus, which is related to lipid metabolism. Specifically, the metabolic pathways of the gut microbiota were mainly enriched in metabolic-related functions (such as lipid metabolism), and there were significant differences in metabolic and immune pathways between the TH4.5 and TH0 groups (p < 0.05). In summary, TH may enhance lipid metabolism by modulating the gut microbiota (especially Akkermansia), thereby promoting the growth of tadpoles. Consequently, a supplementation of 4.5 g/kg or 6 g/kg of TH is recommended for promoting the metamorphosis and growth of tadpoles.

Is thyroid dysfunction a common cause of telogen effluvium?: A retrospective study

Telogen effluvium (TE) is a common cause of hair loss characterized by excessive resting hair shedding. Thyroid dysfunction is one of the possible causes of TE. On the other hand, the link between thyroid disorder and TE is still being debated. The aim of this retrospective is to investigate the link between thyroid dysfunction and TE. This retrospective study included 500 female patients with TE who had thyroid function testing between January 2012 and December 2022. Patients were eligible if they had a confirmed TE diagnosis and thyroid function tests within 3 months of being diagnosed with TE. The thyroid function of the participants was classified as euthyroid, hypothyroidism, or hyperthyroidism. The severity of hair loss was determined using the severity of alopecia tool (SALT) score. The study included 500 TE females, 248 of whom were euthyroid, 150 had hypothyroidism, and 102 had hyperthyroidism. The hypothyroid group had a significantly higher mean SALT score than the other 2 groups. Furthermore, patients in the hypothyroid group had a higher proportion of severe hair loss. The mean SALT score did not differ significantly between groups with normal thyroid function and those with hyperthyroidism. A common cause of TE is thyroid dysfunction, particularly hypothyroidism. Patients with hypothyroidism have more severe hair loss than those with normal thyroid function or hyperthyroidism. To effectively identify and manage such cases, thyroid function testing should be included in the diagnostic workup of patients with TE.

Local modulation of thyroid hormone signaling in the retina affects the development of diabetic retinopathy

Thyroid hormone (TH) dyshomeostasis is associated with poor prognosis in acute and prolonged illness, but its role in diabetic retinopathy (DR) has never been investigated. Here, we characterized the TH system in the retinas of db/db mice and highlighted regulatory processes in MIO-M1 cells. In the db/db retinas, typical functional traits and molecular signatures of DR were paralleled by a tissue-restricted reduction of TH levels. A local condition of low T3 (LT3S) was also demonstrated, which was likely to be induced by deiodinase 3 (DIO3) upregulation, and by decreased expression of DIO2 and of TH receptors. Concurrently, T3-responsive genes, including mitochondrial markers and microRNAs (miR-133-3p, 338-3p and 29c-3p), were downregulated. In MIO-M1 cells, a feedback regulatory circuit was evidenced whereby miR-133-3p triggered the post-transcriptional repression of DIO3 in a T3-dependent manner, while high glucose (HG) led to DIO3 upregulation through a nuclear factor erythroid 2-related factor 2-hypoxia-inducible factor-1 pathway. Finally, an in vitro simulated condition of early LT3S and hyperglycemia correlated with reduced markers of both mitochondrial function and stress response, which was reverted by T3 replacement. Together, the data suggest that, in the early phases of DR, a DIO3-driven LT3S may be protective against retinal stress, while, in the chronic phase, it not only fails to limit HG-induced damage, but also increases cell vulnerability likely due to persistent mitochondrial dysfunction.

A Case of Acute Neurologic Deficit and Hypoglycemia in the Setting of Thyroid Storm and Diabetic Ketoacidosis: A New Clinical Scenario

The simultaneous development of diabetic ketoacidosis (DKA) and thyroid storm (TS) is a rare but potentially lifethreatening condition that requires immediate and targeted treatment. However, their combined diagnosis poses a serious challenge because of the similarities between their clinical manifestations. To date, only a few dozen cases have been described; most of which have been linked to the progression of thyrotoxicosis or uncontrolled hyperglycemia as contributing factors. We present the case of a 37-year-old woman with type 1 diabetes mellitus and Graves' disease who presented with both TS and DKA. She was initially admitted to the emergency department as a suspected case of stroke. Severe hypoglycemia significantly lowered her alertness to TS and probably provoked a sharp hyperthyroid decompensation, thereby leading to subsequent DKA development.

Expressions of mitochondria-related genes in pregnant women with subclinical hypothyroidism, and expressions of miRNAs in maternal and cord blood

BACKGROUND

Subclinical hypothyroidism in pregnancy and definition by upper thyrotropin (TSH) cutoff are controversial. As mitochondria are influenced by thyroid hormones, the purpose in this study was to measure expression of mitochondria-related genes in euthyroid and subclinical hypothyroid pregnant women to obtain more knowledge of potential metabolic consequences of maternal subclinical hypothyroidism. In addition, we wished to test if applied TSH-cutoff significantly changed our results of expressed gene-levels. Moreover, we aimed to identify potential microRNA-biomarkers for subclinical hypothyroidism - markers that could be traced to offspring as well.

METHODS

From a cohort of at-term pregnant women undergoing planned cesarean section, 77 women had expression levels of the mitochondria-related genes Peroxisome Proliferator-activated Receptor-γ coactivator-1β (PGC-1β), mitochondrial Transcription Factor A (TFAM), Superoxide Dismutase 2 (SOD2) and Nuclear Respiratory Factor 2 (NRF-2) determined by qPCR from blood sampled in prior to delivery. Two TSH-cutoff levels defining subclinical hypothyroidism (> 3.0 and > 3.7 mIU/L) were applied for the procession of results, generating two data analyses of the same cohort. In 22 pairwise maternal-cord samples (subclinical hypothyroid/euthyroid-rate 0.5, TSH-cutoff > 3.0 mIU/L), microRNA-expressions (miRNA) were analyzed.

RESULTS

All gene expressions were lower in the subclinical hypothyroid group regardless of applied TSH-cutoff, but insignificant except for PGC-1β at TSH cutoff > 3.0 mIU/L. Two miRNAs (hsa-let-7d-3p and hsa-miR-345-5p) were upregulated in blood from women and offspring (cord blood) with subclinical hypothyroidism.

CONCLUSIONS

A trend towards decreased mitochondrial gene expressions in subclinical hypothyroidism were demonstrated. The miRNAs hsa-let-7d-3p and hsa-miR-345-5p might be potential markers of maternal subclinical hypothyroidism. However, larger studies are needed to verify the findings.

Thyroid Hormone Regulates the Lipid Content of Muscle Fibers, Thus Affecting Physical Exercise Performance

Skeletal muscle (SkM) lipid composition plays an essential role in physiological muscle maintenance and exercise performance. Thyroid hormones (THs) regulate muscle formation and fuel energy utilization by modulating carbohydrates and lipid and protein metabolism. The best-known effects of THs in SkM include the promotion of mitochondrial biogenesis, the fiber-type switch from oxidative to glycolytic fibers, and enhanced angiogenesis. To assess the role of THs on the lipidic composition of SkM fibers, we performed lipidomic analyses of SkM cells and tissues, glucose tolerance experiments, and exercise performance tests. Our data demonstrated that TH treatment induces remodeling of the lipid profile and changes the proportion of fatty acids in SkM. In brief, THs significantly reduced the ratio of stearic/oleic acid in the muscle similar to what is induced by physical activity. The increased proportion of unsaturated fatty acids was linked to an improvement in insulin sensitivity and endurance exercise. These findings point to THs as critical endocrine factors affecting exercise performance and indicate that homeostatic maintenance of TH signals, by improving cell permeability and receptor stability at the cell membrane, is crucial for muscle physiology.

An atypical presentation of hypothyroidism with extremely exaggerated functional impairment

Key Clinical Message

Myopathy-related symptoms are rare manifestations of hypothyroidism. Clinicians should consider hypothyroid myopathy as one of the possible diagnoses for patients with proximal weaknesses.

Abstract

Myopathy-related symptoms are rare manifestations of hypothyroidism. Clinicians should consider hypothyroid myopathy as one of the possible diagnoses for patients with proximal weaknesses. We report a 34-year-old woman, presenting with a new atypical musculoskeletal manifestation of hypothyroidism mimicking polymyositis.

High risk and low prevalence diseases: Thyroid storm

INTRODUCTION

Thyroid storm is a rare but serious condition that carries a high rate of morbidity and even mortality.

OBJECTIVE

This review highlights the pearls and pitfalls of thyroid storm, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence.

DISCUSSION

Thyroid storm is a challenging condition to diagnose and manage in the ED. It is characterized by exaggerated signs and symptoms of thyrotoxicosis and evidence of multiorgan decompensation, usually occurring in the presence of an inciting trigger. Clinical features of thyroid storm may include fever, tachycardia, signs of congestive heart failure, vomiting/diarrhea, hepatic dysfunction, and central nervous system disturbance. There are several mimics including sympathomimetic overdose, substance use disorders, alcohol withdrawal, acute pulmonary edema, aortic dissection, heat stroke, serotonin syndrome, and sepsis/septic shock. Ultimately, the key to diagnosis is considering the disease. While laboratory assessment can assist, there is no single laboratory value that will establish a diagnosis of thyroid storm. Clinical criteria include the Burch-Wartofsky point scale and Japan Thyroid Association diagnostic criteria. ED treatment focuses on diagnosing and managing the trigger; resuscitation; administration of steroids, thionamides, iodine, and cholestyramine; and treatment of hyperthermia and agitation. Beta blockers should be administered in the absence of severe heart failure. The emergency clinician should be prepared for rapid clinical deterioration and employ a multidisciplinary approach to treatment that involves critical care and endocrinology specialists.

CONCLUSIONS

An understanding of thyroid storm can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

Biological and Catalytic Properties of Selenoproteins

Selenocysteine is a catalytic residue at the active site of all selenoenzymes in bacteria and mammals, and it is incorporated into the polypeptide backbone by a co-translational process that relies on the recoding of a UGA termination codon into a serine/selenocysteine codon. The best-characterized selenoproteins from mammalian species and bacteria are discussed with emphasis on their biological function and catalytic mechanisms. A total of 25 genes coding for selenoproteins have been identified in the genome of mammals. Unlike the selenoenzymes of anaerobic bacteria, most mammalian selenoenzymes work as antioxidants and as redox regulators of cell metabolism and functions. Selenoprotein P contains several selenocysteine residues and serves as a selenocysteine reservoir for other selenoproteins in mammals. Although extensively studied, glutathione peroxidases are incompletely understood in terms of local and time-dependent distribution, and regulatory functions. Selenoenzymes take advantage of the nucleophilic reactivity of the selenolate form of selenocysteine. It is used with peroxides and their by-products such as disulfides and sulfoxides, but also with iodine in iodinated phenolic substrates. This results in the formation of Se-X bonds (X = O, S, N, or I) from which a selenenylsulfide intermediate is invariably produced. The initial selenolate group is then recycled by thiol addition. In bacterial glycine reductase and D-proline reductase, an unusual catalytic rupture of selenium-carbon bonds is observed. The exchange of selenium for sulfur in selenoproteins, and information obtained from model reactions, suggest that a generic advantage of selenium compared with sulfur relies on faster kinetics and better reversibility of its oxidation reactions.

Thyroid Axis and Vestibular Physiopathology: From Animal Model to Pathology

A recent work of our group has shown the significant effects of thyroxine treatment on the restoration of postural balance function in a rodent model of acute peripheral vestibulopathy. Based on these findings, we attempt to shed light in this review on the interaction between the hypothalamic-pituitary-thyroid axis and the vestibular system in normal and pathological situations. Pubmed database and relevant websites were searched from inception through to 4 February 2023. All studies relevant to each subsection of this review have been included. After describing the role of thyroid hormones in the development of the inner ear, we investigated the possible link between the thyroid axis and the vestibular system in normal and pathological conditions. The mechanisms and cellular sites of action of thyroid hormones on animal models of vestibulopathy are postulated and therapeutic options are proposed. In view of their pleiotropic action, thyroid hormones represent a target of choice to promote vestibular compensation at different levels. However, very few studies have investigated the relationship between thyroid hormones and the vestibular system. It seems then important to more extensively investigate the link between the endocrine system and the vestibule in order to better understand the vestibular physiopathology and to find new therapeutic leads.

Exposure to per- and polyfluoroalkyl substances in early pregnancy, risk of gestational diabetes mellitus, potential pathways, and influencing factors in pregnant women: A nested case-control study

Although previous studies have reported an association between maternal serum perfluoroalkyl substance (PFAS) exposure and gestational diabetes mellitus (GDM) risk, results have been inconsistent. Few studies have focused on the combined effects of emerging and legacy PFASs on glucose homeostasis while humans are always exposed to multiple PFASs simultaneously. Moreover, the potential pathways by which PFAS exposure induces GDM are unclear. A total of 295 GDM cases and 295 controls were enrolled from a prospective cohort of 2700 pregnant women in Shanghai, China. In total, 16 PFASs were determined in maternal spot serum samples in early pregnancy. We used conditional logistic regression, multiple linear regression, and Bayesian kernel machine regression (BKMR) to examine individual and joint effects of PFAS exposure on GDM risk and oral glucose tolerance test outcomes. The mediating effects of maternal serum biochemical parameters, including thyroid and liver function were further assessed. Maternal perfluorooctanoic acid (PFOA) exposure was associated with an increased risk of GDM (odds ratio (OR) = 1.68; 95% confidence interval (95% CI): 1.10, 2.57), consistent with higher concentrations in GDM cases than controls. Based on mediation analysis, an increase in the free triiodothyronine to free thyroxine ratio partially explained the effect of this association. For continuous glycemic outcomes, positive associations were observed between several PFASs and 1-h and 2-h glucose levels. In BKMR, PFAS mixture exposure showed a positive trend with GDM incidence, although the CIs were wide. These associations were more pronounced among women with normal pre-pregnancy body mass index (BMI). Mixed PFAS congeners may affect glucose homeostasis by increasing 1-h glucose levels, with perfluorononanoic acid found to be a main contributor. Exposure to PFASs was associated with increased risk of GDM and disturbance in glucose homeostasis, especially in normal weight women. The PFAS-associated disruption of maternal thyroid function may alter glucose homeostasis.

NMR-based metabolomics applied to ecotoxicology with zebrafish (Danio rerio) as a prominent model for metabolic profiling and biomarker discovery: Overviewing the most recent approaches

Metabolomics is an innovative approach used in the medical, toxicological, and biological sciences. As an interdisciplinary topic, metabolomics and its relation with the environment and toxicological research are extensive. The use of substances, such as drugs and pesticides, contributes to the continuous releasing of xenobiotics into the environment, harming organisms and their habitats. In this context, fish are important bioindicators of the environmental condition and have often been used as model species. Among them, zebrafish (Danio rerio) presents itself as a versatile and straightforward option due to its unique attributes for research. Zebrafish proves to be a valuable model for toxicity assays and also for metabolomics profiling by analytical tools. Thus, NMR-based metabolomics associated with statistical analysis can reasonably assist researchers in critical factors related to discovering and validating biomarkers through accurate diagnosis. Therefore, this review aimed to report the studies that applied zebrafish as a model for (eco)toxicological assays and essentially utilized NMR-based metabolomics analysis to assess the biochemical profile and thus suggest the potential biological marker.

Uncovering Actions of Type 3 Deiodinase in the Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD)

Metabolic dysfunction-associated fatty liver disease (MAFLD) has gained worldwide attention as a public health problem. Nonetheless, lack of enough mechanistic knowledge restrains effective treatments. It is known that thyroid hormone triiodothyronine (T3) regulates hepatic lipid metabolism, and mitochondrial function. Liver dysfunction of type 3 deiodinase (D3) contributes to MAFLD, but its role is not fully understood. Objective: To evaluate the role of D3 in the progression of MAFLD in an animal model. Methodology: Male/adult Sprague Dawley rats (n = 20) were allocated to a control group (2.93 kcal/g) and high-fat diet group (4.3 kcal/g). Euthanasia took place on the 28th week. D3 activity and expression, Uncoupling Protein 2 (UCP2) and type 1 deiodinase (D1) expression, oxidative stress status, mitochondrial, Krebs cycle and endoplasmic reticulum homeostasis in liver tissue were measured. Results: We observed an increase in D3 activity/expression (p < 0.001) related to increased thiobarbituric acid reactive substances (TBARS) and carbonyls and diminished reduced glutathione (GSH) in the MAFLD group (p < 0.05). There was a D3-dependent decrease in UCP2 expression (p = 0.01), mitochondrial capacity, respiratory activity with increased endoplasmic reticulum stress in the MAFLD group (p < 0.001). Surprisingly, in an environment with lower T3 levels due to high D3 activity, we observed an augmented alpha-ketoglutarate dehydrogenase (KGDH) and glutamate dehydrogenase (GDH) enzymes activity (p < 0.05). Conclusion: Induced D3, triggered by changes in the REDOX state, decreases T3 availability and hepatic mitochondrial capacity. The Krebs cycle enzymes were altered as well as endoplasmic reticulum stress. Taken together, these results shed new light on the role of D3 metabolism in MAFLD.

Loss of p53 activates thyroid hormone via type 2 deiodinase and enhances DNA damage

The Thyroid Hormone (TH) activating enzyme, type 2 Deiodinase (D2), is functionally required to elevate the TH concentration during cancer progression to advanced stages. However, the mechanisms regulating D2 expression in cancer still remain poorly understood. Here, we show that the cell stress sensor and tumor suppressor p53 silences D2 expression, thereby lowering the intracellular THs availability. Conversely, even partial loss of p53 elevates D2/TH resulting in stimulation and increased fitness of tumor cells by boosting a significant transcriptional program leading to modulation of genes involved in DNA damage and repair and redox signaling. In vivo genetic deletion of D2 significantly reduces cancer progression and suggests that targeting THs may represent a general tool reducing invasiveness in p53-mutated neoplasms.

Association between non-alcoholic fatty liver disease and subclinical hypothyroidism in children with obesity

PURPOSE

We aimed (i) evaluating the relationship between non-alcoholic fatty liver disease (NAFLD) and thyroid function tests, (ii) testing if the relationship between NAFLD and thyroid dysfunction could be driven by the obesity and the IR degree, and (iii) exploring the influence of the patatin-like phospholipase domain-containing protein-3 (PNPLA3) I148M and the transmembrane 6 superfamily member 2 (TM6SF2) E167K polymorphisms on the association between NAFLD and thyroid function in children.

METHODS

We examined 2275 children and adolescents with obesity. Subclinical hypothyroidism (SH) was defined by thyroid-stimulating hormone (TSH) > 4.2 μUI/ml with normal fT3 and fT4.

RESULTS

Children with NAFLD showed higher SH prevalence than those without NAFLD (15.7% Vs 7.4%;p = 0.001) and showed an adjusted odds ratio (aOR) to have SH of 1.68 (95% CI:1.01-2.80;p = 0.04) while patients with SH had an aOR to show NAFLD of 2.13(95% CI:1.22-3.73;p = 0.008). Patients having severe obesity and IR degree presented an aOR to show both NAFLD and SH of 3.61 (95% CI:1.78-7.33;p < 0.0001). Subjects with NAFLD carrying the TM6SF2 167 K allele had lower TSH levels than non-carriers (p = 0.03) and showed an aOR to have SH of 0.10 (95% CI: 0.01-0.79;p = 0.02). No differences were found in carriers of the PNPLA3 148 M allele. A general linear model for TSH variance showed a significant association of TSH with TM6SF2 genotypes only in the NAFLD group (p = 0.001).

CONCLUSION

Children with obesity and NAFLD presented increase risk of SH and vice versa likely due to the adverse effect of duration of obesity, obesity degree, and IR. The TM6SF2 E167K exerts a protective role against SH in children with obesity and NAFLD.

Metabolism-Disrupting Chemicals Affecting the Liver: Screening, Testing, and Molecular Pathway Identification

The liver is the central metabolic organ of the body. The plethora of anabolic and catabolic pathways in the liver is tightly regulated by physiological signaling but may become imbalanced as a consequence of malnutrition or exposure to certain chemicals, so-called metabolic endocrine disrupters, or metabolism-disrupting chemicals (MDCs). Among different metabolism-related diseases, obesity and non-alcoholic fatty liver disease (NAFLD) constitute a growing health problem, which has been associated with a western lifestyle combining excessive caloric intake and reduced physical activity. In the past years, awareness of chemical exposure as an underlying cause of metabolic endocrine effects has continuously increased. Within this review, we have collected and summarized evidence that certain environmental MDCs are capable of contributing to metabolic diseases such as liver steatosis and cholestasis by different molecular mechanisms, thereby contributing to the metabolic syndrome. Despite the high relevance of metabolism-related diseases, standardized mechanistic assays for the identification and characterization of MDCs are missing. Therefore, the current state of candidate test systems to identify MDCs is presented, and their possible implementation into a testing strategy for MDCs is discussed.

Does Iodine Influence the Metabolism of Glucose?

Thyroid function and glucose status are linked; experimental, clinical, and epidemiological studies have shown this. Iodine is a vital trace element that is inextricably linked to thyroid hormone synthesis. The latter is also associated with glucose metabolism and diabetes. Recently, some-but not all-studies have shown that iodine is linked to glucose metabolism, glucose intolerance, impaired fasting glucose, prediabetes, diabetes mellitus, or gestational diabetes. In this concise review, we review these studies, focusing on iodine and glucose metabolism and prediabetic conditions or type 2 diabetes mellitus. The potential beneficial effect of iodine on glucose metabolism may be attributed to its antioxidant properties.

Thyrotoxicosis in Africa: a systematic review and meta-analysis of the clinical presentation

Background

Thyrotoxicosis is a common endocrine disorder. The clinical presentation is variable, and it is often misdiagnosed or diagnosed late in Africa. This study was aimed at collating and analyzing the clinical characteristics of the disease across the continent so as to enhance correct and timely diagnosis.

Methods

The study is a systematic review with a meta-analysis. Studies, done in Africa, which documented the clinical features of thyrotoxicosis were selected. African Journal Online (AJOL), PubMed, SCOPUS and Google Scholar, Research Square, SciELO, and medRxiv were systematically searched using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The study quality was assessed using the Newcastle-Ottawa scale. Heterogeneity was determined using I2 statistic and Cochran’s Q test. LFK index and the symmetry of the Doi plot were used to assess publication bias.

Results

The eligible studies were 59 and the total sample size was 9592. The most common symptoms of thyrotoxicosis on the continent included palpitations (69%), weight loss (65%), heat intolerance (64%), tiredness (49%), increased appetite (49%), hyperhidrosis (48%), and insomnia (47%). The most common signs were thyromegaly (88%), tachycardia (67%), sweaty palms (54%), hand tremor (49%), and exophthalmos (49%). Atrial fibrillation, heart failure, and thyrotoxic heart disease were found in 9, 12, and 22% respectively. Other findings were hypertension (25%) and diabetes (9%).

Conclusion

Clinical presentation of thyrotoxicosis varies, and understanding these peculiarities would mitigate misdiagnosis and delayed diagnosis in Africa.

Exploring associations of anthropometric parameters and serum triglycerides with serum thyroid hormones in young women

Establishing links between serum thyroid hormone panel and triglyceride (TG) concentrations with non-invasively obtained measurements of anthropometric parameters of young women may provide preliminary knowledge about the homeostasis of metabolic processes and body composition and about the strategic role of the tested parameters as early screening tests for assessing the health status of apparently healthy women in the period preceding pregnancy. The study was conducted in 381 healthy female students (aged 18-26 years, mean ± SD = 22.1 ± 1.3). Anthropometric indices (BMI, waist-to-hip ratio, FAT%) were calculated and serum concentrations of thyroid hormones (TSH, fT3, fT4) were determined using electrochemiluminescence immunoassays and serum triglycerides (TG) with a commercially available test. No association was established between serum TSH and anthropometric indices in healthy young women. Increased serum concentrations of fT4, fT3 and TG were found in overweight subjects, i.e. BMI > 24.9 kg/m² (p < 0.05). A significant negative association between fT3 and TG was found in underweight subjects (r = - 0.258, p = 0.049) and a significantly positive association in normal-weight subjects (r = 0.139, p = 0.019). In healthy young women differences in BMI are not related to thyroid function. The opposite directions between the associations fT3 vs TG in underweight compared to normal-weight young prepregnant females may suggest dependencies of fT3 and TG in the regulation of specific BMI-dependent metabolic processes.

Mediators of energy homeostasis in hyperthyroidism

Objective

The aim of this study was to assess the effect of hyperthyroidism and its treatment on body weight and composition, insulin resistance, and mediators of appetite and energy homeostasis, namely ghrelin, leptin, adiponectin, and fibroblast growth factor 21 (FGF21).

Subjects and methods

Thirty-five adult patients (27 female and 8 male, aged 39.63 ± 9.70 years) with overt hyperthyroidism were evaluated for leptin, ghrelin, adiponectin, and FGF21 levels; insulin resistance; and body composition using DEXA both at baseline and a minimum of two months following normalization of serum thyroxin on carbimazole treatment. Comparison of means between the baseline and post treatment values was performed by the paired t test for normally distributed parameters and by the Wilcoxon signed-rank test for non-normally distributed data.

Results

Hyperthyroidism correction resulted in an increase in weight from 51.15 ± 8.50 kg to 55.74 ± 8.74 kg (P < 0.001), paradoxically accompanied by a decrease in insulin resistance as measured by HOMA-IR from 1.35 (1.02-1.72) to 0.73 (0.52-0.93) (P < 0.001). Correction of hyperthyroidism was also associated with a decrease in FGF21 from 58 (55-64) to 52 (47-58) pg/mL (P < 0.001) and in leptin levels from 17 (7-36) to 11 (4.6-28) ng/mL (P = 0.03).

Conclusion

Despite lower body weight, thyrotoxicosis is associated with insulin resistance. High levels of thermogenic hormones, leptin, and FGF21 were observed in thyrotoxicosis and may be partly responsible for the excessive heat production typical of this condition.

Cross-Talk between the Cytokine IL-37 and Thyroid Hormones in Modulating Chronic Inflammation Associated with Target Organ Damage in Age-Related Metabolic and Vascular Conditions

Chronic inflammation is considered to be the main mechanism contributing to the development of age-related metabolic and vascular conditions. The phases of chronic inflammation that mediate the progression of target organ damage in these conditions are poorly known, however. In particular, there is a paucity of data on the link between chronic inflammation and metabolic disorders. Based on some of our own results and recent developments in our understanding of age-related inflammation as a whole-body response, we discuss the hypothesis that cross-talk between the cytokine IL-37 and thyroid hormones could be the key regulatory mechanism that justifies the metabolic effects of chronic tissue-related inflammation. The cytokine IL-37 is emerging as a strong natural suppressor of the chronic innate immune response. The effect of this cytokine has been identified in reversing metabolic costs of chronic inflammation. Thyroid hormones are known to regulate energy metabolism. There is a close link between thyroid function and inflammation in elderly individuals. Nonlinear associations between IL-37 and thyroid hormones, considered within the wider clinical context, can improve our understanding of the phases of chronic inflammation that are associated with target organ damage in age-related metabolic and vascular conditions.

Thyroid Hormone Receptor Isoforms Alpha and Beta Play Convergent Roles in Muscle Physiology and Metabolic Regulation

Skeletal muscle is a key energy-regulating organ, skilled in rapidly boosting the rate of energy production and substrate consumption following increased workload demand. The alteration of skeletal muscle metabolism is directly associated with numerous pathologies and disorders. Thyroid hormones (THs) and their receptors (TRs, namely, TRα and TRβ) exert pleiotropic functions in almost all cells and tissues. Skeletal muscle is a major THs-target tissue and alterations of THs levels have multiple influences on the latter. However, the biological role of THs and TRs in orchestrating metabolic pathways in skeletal muscle has only recently started to be addressed. The purpose of this paper is to investigate the muscle metabolic response to TRs abrogation, by using two different mouse models of global TRα- and TRβKO. In line with the clinical features of resistance to THs syndromes in humans, characterized by THRs gene mutations, both animal models of TRs deficiency exhibit developmental delay and mitochondrial dysfunctions. Moreover, using transcriptomic and metabolomic approaches, we found that the TRs–THs complex regulates the Fatty Acids (FAs)-binding protein GOT2, affecting FAs oxidation and transport in skeletal muscle. In conclusion, these results underline a new metabolic role of THs in governing muscle lipids distribution and metabolism.

Perspective: Drawing on Findings From Critical Illness to Explain Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

We propose an initial explanation for how myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) could originate and perpetuate by drawing on findings from critical illness research. Specifically, we combine emerging findings regarding (a) hypoperfusion and endotheliopathy, and (b) intestinal injury in these illnesses with our previously published hypothesis about the role of (c) pituitary suppression, and (d) low thyroid hormone function associated with redox imbalance in ME/CFS. Moreover, we describe interlinkages between these pathophysiological mechanisms as well as “vicious cycles” involving cytokines and inflammation that may contribute to explain the chronic nature of these illnesses. This paper summarizes and expands on our previous publications about the relevance of findings from critical illness for ME/CFS. New knowledge on diagnostics, prognostics and treatment strategies could be gained through active collaboration between critical illness and ME/CFS researchers, which could lead to improved outcomes for both conditions.

Thyroid hormone enhances stem cell maintenance and promotes lineage-specific differentiation in human embryonic stem cells

Background

Thyroid hormone triiodothyronine (T3) is essential for embryogenesis and is commonly used during in vitro fertilization to ensure successful implantation. However, the regulatory mechanisms of T3 during early embryogenesis are largely unknown.

Method

To study the impact of T3 on hPSCs, cell survival and growth were evaluated by measurement of cell growth curve, cloning efficiency, survival after passaging, cell apoptosis, and cell cycle status. Pluripotency was evaluated by RT-qPCR, immunostaining and FACS analysis of pluripotency markers. Metabolic status was analyzed using LC–MS/MS and Seahorse XF Cell Mito Stress Test. Global gene expression was analyzed using RNA-seq. To study the impact of T3 on lineage-specific differentiation, cells were subjected to T3 treatment during differentiation, and the outcome was evaluated using RT-qPCR, immunostaining and FACS analysis of lineage-specific markers.

Results

In this report, we use human pluripotent stem cells (hPSCs) to show that T3 is beneficial for stem cell maintenance and promotes trophoblast differentiation. T3 enhances culture consistency by improving cell survival and passaging efficiency. It also modulates cellular metabolism and promotes energy production through oxidative phosphorylation. T3 helps maintain pluripotency by promoting ERK and SMAD2 signaling and reduces FGF2 dependence in chemically defined culture. Under BMP4 induction, T3 significantly enhances trophoblast differentiation.

Conclusion

In summary, our study reveals the impact of T3 on stem cell culture through signal transduction and metabolism and highlights its potential role in improving stem cell applications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02799-y.

Triiodothyronine (T3) Induces Limited Transcriptional and DNA Methylation Reprogramming in Human Monocytes

Thyroid hormones have immunomodulatory roles, but their effects on the transcriptome and epigenome of innate immune cell types remain unexplored. In this study, we investigate the effects of triiodothyronine (T3) on the transcriptome and methylome of human monocytes in vitro, both in resting and lipopolysaccharide (LPS)-stimulated conditions. In resting monocytes, 5 µM T3 affected the expression of a small number of monocyte-to-macrophage differentiation-associated genes, including TLR4 (p-value < 0.05, expression fold change >1.5). T3 attenuated a small proportion of monocyte-to-macrophage differentiation-associated DNA methylation changes, while specifically inducing DNA methylation changes at several hundred differentially methylated CpG probes (DMPs) (p-value < 0.05, Δβ > 0.05). In LPS-stimulated monocytes, the presence of T3 attenuated the effect of 27% of LPS-induced DMPs (p-value < 0.05, Δβ > 0.05). Interestingly, co-stimulation with T3 + LPS induced a unique DNA methylation signature that was not observed in the LPS-only or T3-only exposure groups. Our results suggest that T3 induces limited transcriptional and DNA methylation remodeling in genes enriched in metabolism and immune processes and alters the normal in vitro LPS response. The overlap between differentially expressed genes and genes associated with DMPs was minimal; thus, other epigenetic mechanisms may underpin the expression changes. This research provides insight into the complex interplay between thyroid hormones, epigenetic remodeling, and transcriptional dynamics in monocytes.

T3-induced enhancement of mitochondrial Ca2+ uptake as a boost for mitochondrial metabolism

Thyroid hormones act as master regulators of cellular metabolism. Thereby, the biologically active triiodothyronine (T3) induces the expression of genes to enhance mitochondrial metabolic function. Notably, Ca²⁺ ions are necessary for the activity of dehydrogenases of the tricarboxylic acid cycle and, thus, mitochondrial respiration. We investigated whether treating HeLa cells with T3 causes alterations in mitochondrial Ca²⁺ ([Ca²⁺]_mito) levels. Real-time measurements by fluorescence microscopy revealed that treatment with T3 for 3 h induces a significant increase in basal [Ca²⁺]_mito levels and [Ca²⁺]_mito uptake upon the depletion of the endoplasmic reticulum (ER) Ca²⁺ store, while cytosolic Ca²⁺ levels remained unchanged. T3 incubation was found to upregulate mRNA expression levels of uncoupling proteins 2 and 3 (UCP2, UCP3) and of protein arginine methyltransferase 1 (PRMT1). Live-cell imaging revealed that T3-induced enhancement of mitochondrial Ca²⁺ uptake depends on the mitochondrial Ca²⁺ uniporter (MCU), UCP2, and PRMT1 that are essential for increased mitochondrial ATP ([ATP]_mito) production after T3 treatment. Besides, increased [Ca²⁺]_mito and [ATP]_mito levels correlated with enhanced production of reactive oxygen species (ROS) in mitochondria. Notably, ROS scavenging causes mitochondrial Ca²⁺ elevation and outplays the impact of T3 on [Ca²⁺]_mito homeostasis. Based on these results, we assume that thyroid hormones adjust [Ca²⁺]_mito homeostasis by modulating the UCP2- and PRMT1-balanced [Ca²⁺]_mito uptake via MCU in case of physiological ROS levels to convey their impact on mitochondrial ATP and ROS production.

Thyroid hormone regulates glutamine metabolism and anaplerotic fluxes by inducing mitochondrial glutamate aminotransferase GPT2

Thyroid hormones (THs) are key metabolic regulators coordinating short- and long-term energy needs. In skeletal muscle, THs modulate energy metabolism in pathophysiological conditions. Indeed, hypo- and hyperthyroidism are leading causes of muscle weakness and strength; however, the metabolic pathways underlying these effects are still poorly understood. Using molecular, biochemical, and isotope-tracing approaches combined with mass spectrometry and denervation experiments, we find that THs regulate glutamine metabolism and anaplerotic fluxes by up-regulating the glutamate pyruvate transaminase 2 (GPT2) gene. In humans, GPT2 autosomal recessive mutations cause a neurological syndrome characterized by intellectual disability, microcephaly, and progressive motor symptoms. Here, we demonstrate a role of the TH/GPT2 axis in skeletal muscle in which it regulates muscle weight and fiber diameter in resting and atrophic conditions and results in protection from muscle loss during atrophy. These results describe an anabolic route by which THs rewire glutamine metabolism toward the maintenance of muscle mass.

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THs induce the expression of the mitochondrial GPT2 gene in skeletal muscle

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The GPT2 up-regulation by THs enhances anaplerotic cycles and α-KG production

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GPT2 is reduced during muscle atrophy and is reactivated by THs treatment

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GPT2 KO^+/– mice undergo muscle loss that is partially attenuated by THs

Nonthyroidal Illness Syndrome: To Treat or Not to Treat? Have We Answered the Question? A Review of Metanalyses

BACKGROUND AND OBJECTIVE

Nonthyroidal Illness Syndrome (NTIS) occurs in approximately 70% of patients admitted to Intensive Care Units (ICU)s and has been associated with increased risk of death. Whether patients with NTIS should receive treatment with thyroid hormones (TH)s is still debated. Since many interventional randomized clinical trials (IRCT)s were not conclusive, current guidelines do not recommend treatment for these patients. In this review, we analyze the reasons why TH treatment did not furnish convincing results regarding possible beneficial effects in reported IRCTs.

METHODS

We performed a review of the metanalyses focused on NTIS in critically ill patients. After a careful selection, we extracted data from four metanalyses, performed in different clinical conditions and diseases. In particular, we analyzed the type of TH supplementation, the route of administration, the dosages and duration of treatment and the outcomes chosen to evaluate the results.

RESULTS

We observed a marked heterogeneity among the IRCTs, in terms of type of TH supplementation, route of administration, dosages and duration of treatment. We also found great variability in the primary outcomes, such as prevention of neurological alterations, reduction of oxygen requirements, restoration of endocrinological and clinical parameters and reduction of mortality.

CONCLUSIONS

NTIS is a frequent finding in critical ill patients. Despite several available IRCTs, it is still unclear whether NTIS should be treated or not. New primary endpoints should be identified to adequately validate the efficacy of TH treatment and to obtain a clear answer to the question raised some years ago.

Proteomics and Organoid Culture Reveal the Underlying Pathogenesis of Hashimoto's Thyroiditis

Hashimoto’s thyroiditis (HT) is an autoimmune disease, and its incidence continues to rise. Although scientists have studied this disease for many years and discovered the potential effects of various proteins in it, the specific pathogenesis is still not fully comprehended. To understand HT and translate this knowledge to clinical applications, we took the mass spectrometric analysis on thyroid tissue fine-needle puncture from HT patients and healthy people in an attempt to make a further understanding of the pathogenesis of HT. A total of 44 proteins with differential expression were identified in HT patients, and these proteins play vital roles in cell adhesion, cell metabolism, and thyroxine synthesis. Combining patient clinical trial sample information, we further compared the transient changes of gene expression regulation in HT and papillary thyroid carcinoma (PTC) samples. More importantly, we developed patient-derived HT and PTC organoids as a promising new preclinical model to verify these potential markers. Our data revealed a marked characteristic of HT organoid in upregulating chemokines that include C-C motif chemokine ligand (CCL) 2 and CCL3, which play a key role in the pathogenesis of HT. Overall, our research has enriched everyone’s understanding of the pathogenesis of HT and provides a certain reference for the treatment of the disease.