Thyroid dysfunction associated with follicular cell steatosis in obese male mice and humans

Metabolic syndrome and risk of subclinical hypothyroidism: a systematic review and meta-analysis

Background

Subclinical hypothyroidism (SCH) is a common endocrine subclinical disorder, the main adverse consequences of which are the development of clinical hypothyroidism and the promotion of ischemic heart disease. Metabolic syndrome (MetS) is a collection of metabolic problems. The goal of this meta-analysis was to evaluate the relationship between MetS and SCH.

Methods

Suitable publications were identified using PubMed, Embase, and the Cochrane Library. The meta-analysis included only studies in English that reported odds ratio (OR) data for MetS and SCH. Two researchers combined data using a random-effects model. OR and 95% confidence intervals (CIs) were used to present the results.

Results

MetS was associated with an elevated risk of developing SCH (OR 2.56, 95% CI 1.44-4.55). However, the individual components of MetS were not associated with the risk of SCH. Subgroup analysis revealed that different definitions of MetS had varying effects on SCH. Sensitivity analysis confirmed that our results were robust.

Conclusions

This meta-analysis indicates that patients with MetS have an increased risk of SCH, while there is no significant association between the five individual components of MetS and the risk of SCH.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023454415.

Exploring the link between obesity and hypothyroidism in autoimmune thyroid diseases: a metabolic perspective

Background: The management of primary hypothyroidism demands a comprehensive approach that encompasses both the implications of autoimmune thyroid disease and the distinct effects posed by obesity and metabolic irregularities. Despite its clinical importance, the interplay between obesity and hypothyroidism, especially in the context of metabolic perspectives, is insufficiently explored in existing research. This study endeavors to classify hypothyroidism by considering the presence of autoimmune thyroid disease and to examine its correlation with various metabolic obesity phenotypes. Method: This research was conducted by analyzing data from 1,170 individuals enrolled in the Thyroid Disease Database of Shandong Provincial Hospital. We assessed four distinct metabolic health statuses among the participants: Metabolically Healthy No Obese Metabolically Healthy Obese Metabolically Unhealthy No Obese and Metabolically Unhealthy Obese Utilizing logistic regression, we investigated the association between various metabolic obesity phenotypes and hypothyroidism. Results: The study revealed a significant correlation between the Metabolically Unhealthy Obese (MUO) phenotype and hypothyroidism, particularly among women who do not have thyroid autoimmunity. Notably, the Metabolically Unhealthy No Obese (MUNO) phenotype showed a significant association with hypothyroidism in individuals with thyroid autoimmunity, with a pronounced prevalence in women. Furthermore, elevated levels of triglycerides and blood glucose were found to be significantly associated with hypothyroidism in men with thyroid autoimmunity and in women without thyroid autoimmunity. Conclusion: Effective treatment of hypothyroidism requires a thorough understanding of the process of thyroid autoimmune development. In patients without concurrent thyroid autoimmunity, there is a notable correlation between obesity and metabolic issues with reduced thyroid function. Conversely, for patients with thyroid autoimmunity, a focused approach on managing metabolic abnormalities, especially triglyceride levels, is crucial.

Maternal undernutrition results in transcript changes in male offspring that may promote resistance to high fat diet induced weight gain

Maternal nutrition during embryonic development and lactation influences multiple aspects of offspring health. Using mice, this study investigates the effects of maternal caloric restriction (CR) during mid-gestation and lactation on offspring neonatal development and on adult metabolic function when challenged by a high fat diet (HFD). The CR maternal model produced male and female offspring that were significantly smaller, in terms of weight and length, and females had delayed puberty. Adult offspring born to CR dams had a sexually dimorphic response to the high fat diet. Compared to offspring of maternal control dams, adult female, but not male, CR offspring gained more weight in response to high fat diet at 10 weeks. In adipose tissue of male HFD offspring, maternal undernutrition resulted in blunted expression of genes associated with weight gain and increased expression of genes that protect against weight gain. Regardless of maternal nutrition status, HFD male offspring showed increased expression of genes associated with progression toward nonalcoholic fatty liver disease (NAFLD). Furthermore, we observed significant, sexually dimorphic differences in serum TSH. These data reveal tissue- and sex-specific changes in gene and hormone regulation following mild maternal undernutrition, which may offer protection against diet induced weight gain in adult male offspring.

Evaluation the Effect of Serum Lead Levels on Thyroid Function in Battery Industry Workers

Objective

To assess the relationships between blood lead levels and thyroid functional tests in battery industry workers.

Methods and Materials

This cross-sectional study was performed on 100 personnel of a battery factory in 2019. The checklist including demographic information of employees (age, sex, work experience, smoking, etc.) of the work shift, work environment, and duration of work was completed. Venous blood samples were also taken from the participants to check blood levels of lead and thyroid hormones.

Results

The mean age of participants was 36.1 ± 5.6 years and their mean TSH and lead levels were 3.69 ± 2.45 mIU/L and 297.9 ± 174.2 μg/L, respectively. Participants were divided into two groups based on job duties: administrative and working in the production line. Participants were divided into two groups based on blood lead levels: normal (less than 300 μg/L) and high lead level (more than 300 μg/L). Only the work experience between these two groups was significantly different and was higher in the high lead group compared to the normal lead group and no significant difference was observed between different groups based on lead level in terms of TSH level and thyroid hormones.

Conclusion

Our study showed that although the amount of whole blood lead concentration is not related to thyroid hormone levels and thyroid function, but with increasing work experience, the amount of whole blood lead also increases significantly and since lead poisoning can have many health hazards, employers must plan to minimize the lead exposure of workers and provide protective equipment for workers.

Fructose consumption induces molecular adaptations involving thyroid function and thyroid-related genes in brown adipose tissue in rats

The increasing incidence of metabolic diseases is in part due to the high fructose consumption, a carbohydrate vastly used in industry, with a potent lipogenic capacity. Thyroid hormones (TH) are essential for metabolism regulation and are associated with changes in body weight, energy expenditure, insulin sensitivity, and dyslipidemia. This study aimed to investigate the influence of fructose intake on thyroid function and thyroid-related genes. Male Wistar rats were divided into Control (CT, n=8) and Fructose (FT - 10% in drinking water, n=8) groups for three weeks. The FT group showed higher glycemia and serum triacylglycerol, indicating metabolic disturbances, and increased thyroid mass, accompanied by higher expression of Srebf1c and Lpl, suggesting increased lipid synthesis. The FT group also presented higher expression of Tpo and Dio1 in the thyroid, suggesting activation of the thyroid gland, but with no alterations in serum TH concentrations. Brown adipose tissue (BAT) of the FT group exhibited higher expression of Dio2, Thra, and Thrb, indicating increased T3 intra-tissue bioavailability and signaling. These responses were accompanied by increased BAT mass and higher expression of Adrb3, Pparg, Srebf1c, Fasn, Ppara, and Ucp1, suggesting increased BAT adrenergic sensitivity, lipid synthesis, oxidation, and thermogenesis. Therefore, short-term fructose consumption induced thyroid molecular alterations and increased BAT expression of thyroid hormone-related signaling genes that potentially contributed to higher BAT activity.

Association between different metabolic phenotypes and the development of hypothyroidism: 9 years follow-up of Tehran thyroid study

PURPOSE

The association between metabolic phenotypes and thyroid function has not yet been established; therefore, this study examined whether different metabolic phenotypes are associated with the development of hypothyroidism.

METHODS

Study participants were selected from the Tehran Thyroid Study (TTS). A total of 3338 euthyroid adults were included and categorized into four obesity phenotype groups: metabolically healthy normal weight (MHNW), metabolically healthy obese (MHO), metabolically unhealthy normal weight (MUNW), and metabolically unhealthy obese (MUO). The participants were assessed at baseline and during three follow-up studies at three-year intervals. Multiple logistic regression analysis was used to examine the relationship between metabolic phenotypes and the development of hypothyroidism.

RESULTS

In the total population, the chi-square test was only significant (P=0.008) in 3^rd year with a higher prevalence of hypothyroidism in the MUNW phenotype, followed by MHO, MUO, and MHNW. Moreover, in the 3^rd and 9^th years of follow-up, hypothyroidism was more prevalent in MUO only in male subjects (P=0.002 and 0.035, respectively). In the unadjusted model, the MHO phenotype increased the odds of hypothyroidism compared with the MHNW phenotype (OR=1.51; 95% CI=1.04, 2.18; P-value=0.031). After adjusting for confounding factors, the odds of hypothyroidism were higher in the MUNW (OR=1.86; 95% CI=1.17, 2.96; P-value=0.008), MHO (OR=1.71; 95% CI=1.09, 2.67; P-value=0.018), and MUO (OR=1.64; 95% CI=1.03, 2.62; P-value=0.036) phenotypes than in the MHNW group. The MUNW phenotype increased the risk of hypothyroidism compared to MHNW, only in males. However, in females, the MHO phenotype increased the risk of hypothyroidism compared to MHNW.

CONCLUSION

Both obesity and metabolic abnormalities are associated with hyperthyroidism. Healthy metabolic and weight maintenance were associated with a lower risk of hypothyroidism in males and females.

Adipocyte signaling affects thyroid-specific gene expression via down-regulation of TTF-2/FOXE1

Obesity affects thyroid gland function. Hypothyroidism, thyroid nodules, goiter, and thyroid cancer are more frequent in patients with higher BMI values. Although these data are supported by many clinical and epidemiological studies, our knowledge is very scarce at the molecular level. In this study, we present the first experimental evidence that adipocyte signaling downregulates the expression of thyroid-specific transcription factor 2 (TTF-2/FoxE1). It plays a crucial role in thyroid development and thyroid homeostasis and it is strictly connected to thyroid cancer as well. We provide in vivo and in vitro evidence that inhibition of TTF-2/FoxE1 gene expression is mediated by adipocyte signaling.

Adrenomedullin2 stimulates progression of thyroid cancer in mice and humans under nutrient excess conditions

Thyroid cancer is associated with genetic alterations, e.g. BRAF^V600E , which may cause carcinomatous changes in hormone-secreting epithelial cells. Epidemiological studies have shown that overnutrition is related to the development and progression of cancer. In this study, we attempted to identify the cell nonautonomous factor responsible for the progression of BRAF^V600E thyroid cancer under overnutrition conditions. We developed a mouse model for inducible thyrocyte-specific activation of BRAF^V600E , which showed features similar to those of human papillary thyroid cancer. LSL-Braf^V600E ;TgCreER^T2 showed thyroid tumour development in the entire thyroid, and the tumour showed more abnormal cellular features with mitochondrial abnormalities in mice fed a high-fat diet (HFD). Transcriptomics revealed that adrenomedullin2 (Adm2) was increased in LSL-Braf^V600E ;TgCreER^T2 mice fed HFD. ADM2 was upregulated on the addition of a mitochondrial complex I inhibitor or palmitic acid with integrated stress response (ISR) in cancer cells. ADM2 stimulated protein kinase A and extracellular signal-regulated kinase in vitro. The knockdown of ADM2 suppressed the proliferation and migration of thyroid cancer cells. We searched The Cancer Genome Atlas and Genotype-Tissue Expression databases and found that increased ADM2 expression was associated with ISR and poor overall survival. Consistently, upregulated ADM2 expression in tumour cells and circulating ADM2 molecules were associated with aggressive clinicopathological parameters, including body mass index, in thyroid cancer patients. Collectively, we identified that ADM2 is released from cancer cells under mitochondrial stress resulting from overnutrition and acts as a secretory factor determining the progressive properties of thyroid cancer. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Histological pattern and gene expression profiling of thyroid tissue in subjects with obesity

PURPOSE

Subjects with obesity may exhibit an increase in serum TSH concentrations. Several mechanisms have been proposed to explain this association, including the presence of a compensatory mechanism to counterbalance an accelerated turnover of thyroid hormones in subjects with obesity. This study aimed at evaluating whether the thyroids of subjects with obesity differs from those of normal-weight individuals regarding histology and gene expression profiling.

METHODS

Ninety-eight patients were selected among those scheduled for thyroidectomy. At histology, thyroid tissue samples were investigated for the presence of adipocytes and/or lymphocyte infiltration. In a subset of patients, the expression at mRNA level of several genes involved in metabolic pathways and immune cell-related mechanisms was quantified by NanoString Technology.

RESULTS

The presence of adipose cells was documented in thyroid specimens from 40% normal weight, 52.9% overweight and 73.5% patients with obesity. The number of infiltrating adipocytes was greater in specimens of patients with overweight or obesity compared to normal weight. The lymphocytes common antigen (CD45) and mast cell (MC) scores, and the number of CD3+ and CD8+ lymphocytes were higher in patients with overweight and obesity than in normal-weight subjects. Several genes involved in metabolic pathways were differently expressed in patients with overweight or obesity compared to normal weight, with upregulation of Leptin receptor and downregulation of Fatty Acid-Binding Protein 5.

CONCLUSIONS

Increased BMI is associated with adipocyte and lymphocyte infiltration of the thyroid, not related to an autoimmune process, which might affect thyroid function in subjects with obesity. A differential gene expression profiling of metabolic and immune pathways in thyroid tissues of patients with obesity was also observed.

Impaired Glucose Metabolism, Anti-Diabetes Medications, and Risk of Thyroid Cancer

Simple Summary

An epidemiologic link exists between obesity, insulin resistance, diabetes, and some cancers, such as breast cancer and colon cancer. The prevalence of obesity and diabetes is increasing, and additional epidemiologic data suggest that there may be a link between obesity and risk of thyroid abnormalities. Factors that may link obesity and diabetes with thyroid proliferative disorders include elevated circulating levels of insulin, increased body fat, high blood sugars, and exogenous insulin use. However, mechanisms underlying associations of obesity, diabetes, and thyroid proliferative disorders are not yet fully understood. The present manuscript reviews and summarizes current evidence of mechanisms and epidemiologic associations of obesity, insulin resistance, and use of anti-diabetes medications with benign and malignant proliferative disorders of the thyroid.

Abstract

The prevalence of obesity is progressively increasing along with the potential high risk for insulin resistance and development of type 2 diabetes mellitus. Obesity is associated with increased risk of many malignancies, and hyperinsulinemia has been proposed to be a link between obesity and cancer development. The incidence of thyroid cancer is also increasing, making this cancer the most common endocrine malignancy. There is some evidence of associations between obesity, insulin resistance and/or diabetes with thyroid proliferative disorders, including thyroid cancer. However, the etiology of such an association has not been fully elucidated. The goal of the present work is to review the current knowledge on crosstalk between thyroid and glucose metabolic pathways and the effects of obesity, insulin resistance, diabetes, and anti-hyperglycemic medications on the risk of thyroid cancer development.

The association of obesity with thyroid carcinoma risk

Background

The prevalence of obesity and an increased incidence of thyroid carcinoma (TC) threaten public health in parallel on a global scale. Sufficient evidence supports excess body fatness in thyroid carcinogenesis, and the role and anthropometric markers of obesity have been causally associated with the rising risk of TC.

Methods

A literature search was conducted in PubMed. Studies focused on the effect of obesity in TC.

Results

This review mainly discusses the global incidence and prevalence of obesity‐related TC. We also review the role of obesity in TC and potential clinical strategies for obesity‐related TC.

Conclusions

Excess body fatness in early life and TC survival initiate adverse effects later in life.

The incidence of thyroid cancer has been increasing in the last decades all over the world. Such a steady growth cannot be entirely attributable to more sensitive diagnostic procedures. Obesity has increased with sufficient rapidity in the same time frame and may as possible promoters and modifiable risk factors for thyroid cancer in recent years. The aim of this review was to focus on the relationship between obesity and the risk of thyroid cancer. Obesity seems to play a relevant role in thyroid cancer carcinogenesis as well as in its severity and aggressiveness. The possible underlying mechanism is involved chronic inflammation mediated by cytokines, leptin, and adiponectins.

Cell non-autonomous effect of hepatic growth differentiation factor 15 on the thyroid gland

The thyroid gland plays an essential role in the regulation of body energy expenditure to maintain metabolic homeostasis. However, to date, there are no studies investigating the morphological and functional changes of the thyroid gland due to mitochondrial stress in metabolic organs such as the liver. We used data from the Genotype-Tissue Expression portal to investigate RNA expression patterns of the thyroid gland according to the expression of growth differentiation factor 15 (GDF15) such as the muscles and liver. To verify the effect of hepatic GDF15 on the thyroid gland, we compared the morphological findings of the thyroid gland from liver-specific GDF15 transgenic mice to that of wild type mice. High GDF15 expression in the muscles and liver was associated with the upregulation of genes related to hypoxia, inflammation (TGF-α via NFκB), apoptosis, and p53 pathway in thyroid glands. In addition, high hepatic GDF15 was related to epithelial mesenchymal transition and mTORC1 signaling. Electron microscopy for liver-specific GDF15 transgenic mice revealed short mitochondrial cristae length and small mitochondrial area, indicating reduced mitochondrial function. However, serum thyroid stimulating hormone (TSH) level was not significantly different. In our human cohort, those with a high serum GDF15 level showed high fasting glucose, alanine transaminase, and alkaline phosphatase but no difference in TSH, similar to the data from our mice model. Additionally, high serum GDF15 increased the risk of lymph node metastasis to lateral neck. The hepatic GDF15 affected thyroid morphogenesis via a TSH-independent mechanism, affecting aggressive features of thyroid cancers.

The Association Between Serum Palmitic Acid and Thyroid Function

AIM

Emerging evidence indicates that palmitic acid (PA) can regulate the progression and development of many diseases. However, the studies examining the association between PA and thyroid function remain sparse. We aimed to investigate the association between serum PA (sPA) and thyroid function in the US population.

METHODS

In this retrospective study, a cross-sectional analysis was performed using the data pooled from the database of the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2012. The thyroid parameters investigated were mainly free triiodothyronine (FT3), free thyroxine (FT4), total T3 (TT3), TT4, thyroglobulin (Tg), thyroid-stimulating hormone (TSH), anti-thyroglobulin antibody (TgAb), and anti-thyroperoxidase antibody (TPOAb). The central sensitivity to thyroid function was evaluated by the thyroid feedback quantile-based index (TFQI), thyrotrophin thyroxine resistance index (TT4RI), and thyrotropin index (TSHI). The FT3 to FT4 ratio (FT3/FT4) was employed to evaluate peripheral sensitivity to thyroid hormones. Multiple imputation was applied to handle the missing data, and weighted multivariable linear regression, subgroup, and interaction analyses were then employed to estimate the association between sPA and thyroid parameters.

RESULTS

In the 737 adults, after adjusting covariates, we demonstrated a significant negative association between sPA and FT4 [β = -1.078, 95% confidence interval (CI): -1.729 to -0.427], as well as a positive relationship between sPA and FT3/FT4 ratio (β = 0.073, 95% CI: 0.044 to 0.102). These results did not change on multiple imputations. In the subgroup analyses, the associations were more significant in male and obese subjects.

CONCLUSION

This investigation demonstrated the significant correlation between sPA and thyroid dysfunction, which suggested the close relationship between lipotoxicity and hypothyroidism or subclinical hypothyroidism. Future research is required to confirm these findings.

Differential lipids in pregnant women with subclinical hypothyroidism and their correlation to the pregnancy outcomes

Subclinical hypothyroidism (SCH) has become a prevalent complication in pregnancy. Recent research links SCH to disturbed thyroid lipid profile; however, it is unclear how lipid metabolism disorders contribute to the pathogenesis of SCH during pregnancy. Thus, we used nontargeted lipidomics to identify and compare the lipids and metabolites expressed by pregnant women with SCH and healthy pregnant women. Multivariate analysis revealed 143 lipid molecules differentially expressed between the SCH group and the control group. Based on fold change, 30 differentially expressed lipid metabolites are potential biomarkers. KEGG pathway enrichment analysis showed that the differentially expressed metabolites participate in several pathways, including response to pathogenic Escherichia coli infection, regulation of lipolysis in adipocytes, metabolic pathways, glycerophospholipid metabolism, and fat digestion and absorption pathways. Correlation analyses revealed sphingomyelin (SM) and phosphatidylcholine (PC) positively correlate to tumor necrosis factor-α (TNF-α), C-reactive protein (CRP), and interleukin-6 (IL-6), while phosphatidylglycerol (PG), and phosphatidylinositol (PI) negatively correlate with them. In addition, PG positively correlates to birth weight. Thus, the lipid profile of pregnant women with SCH is significantly different from that of healthy pregnant women. Lipid molecules associated with the differential lipid metabolism, such as SM, phosphatidylethanolamine (PE), and PI, should be further investigated for their roles in the pathogenesis of SCH in pregnancy, as they might be targets for reducing the incidence of adverse pregnancy outcomes.

The association between BMI, smoking, drinking and thyroid disease: a cross-sectional study in Wuhan, China

BACKGROUND

There is no clear conclusion on the relationship between thyroid disease and obesity and lifestyle factors such as smoking and drinking. In this study, we analysed the association of body mass index (BMI), smoking and drinking with subclinical hypothyroidism (SHO) and thyroid nodules (TNs) with the results of a cross-sectional survey of urban residents in central China and discussed the potential mechanism linking these predictive factors and the two diseases.

METHODS

This study included 1279 participants who were recruited from a Chinese community in 2011 and 2012. A questionnaire, laboratory examination and ultrasound diagnosis were conducted on these participants. Binary logistic regression analysis was used to analyse these factors.

RESULTS

Overweight (BMI ≥ 25 kg/m²) was closely related to SHO and TNs in univariate and multivariate logistic regression analyses. Smoking had a protective effect on SHO and TNs, while drinking had a protective effect on TNs in univariate logistic regression and multivariate logistic regression with some covariates, but there was no significant difference between smoking and drinking and the two kinds of thyroid diseases in multivariate logistic regression analysis with all the covariates. In subgroup analysis, BMI ≥ 25 kg/m2 was significantly associated with SHO in people with positive thyroid antibodies (odds ratio (OR) = 2.221, 95 % confidence interval (CI): 1.168-4.184, P = 0.015) and smokers (OR = 2.179, 95 % CI: 1.041-4.561, P = 0.039). BMI ≥ 25 kg/m2 was significantly associated with TNs in people over 60 years old (OR = 2.069, 95 % CI: 1.149-3.724, P = 0.015) and drinkers (OR = 3.065, 95 % CI: 1.413-6.648, P = 0.005). Drinking alcohol had a protective effect on TNs in smokers (OR = 0.456, 95 % CI: 0.240-0.865, P = 0.016) and people with BMI ≥ 25 kg/m² (OR = 0.467, 95 % CI: 0.236-0.925, P = 0.029). No significant association was found between smoking and the two thyroid diseases in different subgroups.

CONCLUSIONS

Obesity is a risk factor for both TNs and SHO, especially in elderly individuals and people with positive thyroid autoantibodies. Obesity and metabolic syndrome may be more associated with TNs than SHO. Smoking may have a protective effect on thyroid disease, while drinking may have a protective effect only on TNs.

Obesity and Thyroid Axis

Development of obesity is primarily the result of imbalance between energy intake and energy expenditure. Thyroid hormones influence energy expenditure by regulating cellular respiration and thermogenesis and by determining resting metabolic rate. Triiodothyronine influences lipid turnover in adipocytes and impacts appetite regulation through the central nervous system, mainly the hypothalamus. Thyroid-stimulating hormone may also influence thermogenesis, suppress appetite and regulate lipid storage through lipolysis and lipogenesis control. Subclinical hypothyroidism may induce changes in basal metabolic rate with subsequent increase in BMI, but obesity can also affect thyroid function via several mechanisms such as lipotoxicity and changes in adipokines and inflammatory cytokine secretion. The present study investigated the complex and mutual relationships between the thyroid axis and adiposity.

Association between different obesity phenotypes and hypothyroidism: a study based on a longitudinal health management cohort

PURPOSE

Obese individuals have an increased risk of hypothyroidism. This study investigated the sex-specific association between obesity phenotypes and the development of hypothyroidism.

METHODS

The study population was derived from a health management cohort in Shandong Provincial Hospital from 2012 to 2016. In total, 9011 baseline euthyroid adults were included and classified into four groups according to obesity phenotype: metabolically healthy nonobese (MHNO), metabolically healthy obese (MHO), metabolically unhealthy nonobese (MUNO), and metabolically unhealthy obese (MUO). The median follow-up time was 1.92 (1.00-2.17) years. Incidence density was evaluated and a generalized estimation equation method was used to investigate the associations between obesity phenotypes and the development of hypothyroidism.

RESULTS

The incidence densities of hypothyroidism in males with a consistent obesity phenotype were 12.19 (8.62-16.76), 15.87 (11.39-21.56), 14.52 (6.74-27.57), and 19.88 (14.06-27.34) per 1000 person-years in the MHNO, MHO, MUNO, and MUO groups, respectively. After adjusting for confounding factors, compared with the MHNO phenotype, the MHO, MUNO, and MUO phenotypes were independent risk factors for developing hypothyroidism in males. In the subgroup analysis, the MHO and MUO phenotypes were independent risk factors for developing hypothyroidism in males under 55 years, while the MUNO phenotype was an independent risk factor in males over 55 years. The MHO, MUNO, and MUO phenotypes were not independent risk factors for hypothyroidism in females.

CONCLUSION

Both obesity and metabolic abnormities are associated with a higher risk of hypothyroidism in males. The underlying mechanism of the sex and age differences in this association needs further investigation.

Structure and genetic variants of thyroglobulin: Pathophysiological implications

Thyroglobulin (TG) plays a main role in the biosynthesis of thyroid hormones (TH), and, thus, it is involved in a wide range of vital functions throughout the life cycle of all vertebrates. Deficiency of TH production due to TG genetic variants causes congenital hypothyroidism (CH), with devastating consequences such as intellectual disability and impaired growth if untreated. To this day, 229 variations in the human TG gene have been identified while the 3D structure of TG has recently appeared. Although TG deficiency is thought to be of autosomal recessive inheritance, the introduction of massive sequencing platforms led to the identification of a variety of monoallelic TG variants (combined with mutations in other thyroid gene products) opening new questions regarding the possibility of oligogenic inheritance of the disease. In this review we discuss remarkable advances in the understanding of the TG architecture and the pathophysiology of CH associated with TG defects, providing new insights for the management of congenital disorders as well as counseling benefits for families with a history of TG abnormalities. Moreover, we summarize relevant aspects of TH synthesis within TG and offer an updated analysis of animal and cellular models of TG deficiency for pathophysiological studies of thyroid dyshormonogenesis while highlighting perspectives for new investigations. All in all, even though there has been sustained progress in understanding the role of TG in thyroid pathophysiology during the past 50 years, functional characterization of TG variants remains an important area of study for future advancement in the field.

Statin Use and Benefits of Thyroid Function: A Retrospective Cohort Study

PURPOSE

Previous studies have suggested that cholesterol may influence thyroid function. Since statins are widely used for their cholesterol-lowering effect, we aimed to assess the association between statin use and thyroid function, and also to explore the role of the cholesterol-lowering effect in it.

METHODS

We performed a retrospective cohort study derived from REACTION study. Eligible subjects receiving statin therapy were included in the statin group, and sex-, age-, total cholesterol (TC)-, and thyroid function-matched participants without lipid-lowering therapy were included in the control group. The median follow-up time was three years. Outcomes of thyroid function were evaluated at the end of follow-up. We used multivariable regression models to assess the association between statin use and outcomes of thyroid function, and also performed mediation analyses to explore the role of cholesterol in it.

RESULTS

A total of 5,146 participants were screened, and 201 eligible subjects in the statin group and 201 well-matched subjects in the control group were analyzed. At the end of follow-up, TC and thyroid-stimulating hormone (TSH) levels in the statin group were lower than those in the control group (both p < 0.05), and the percentage of euthyroid subjects was higher in the statin group (88.06% vs. 76.12%, p = 0.002). The incidence rate of subclinical hypothyroidism (SCH) in euthyroid subjects was lower in the statin group (6.29% vs. 14.86%, p = 0.009), and the remission rate among subjects with SCH was higher in the statin group (50.00% vs. 15.38%, p = 0.008). In multivariable regression analyses, statin use was independently associated with lower TSH levels and higher odds to be euthyroid (OR 2.335, p = 0.004) at the end of follow-up. Mediation analyses showed the association between statin use and TSH levels were mediated by TC changes during follow-up.

CONCLUSION

Statin use was associated with benefits of thyroid function, and TC changes serve as a mediator of the association between statin use and TSH levels. Further studies are needed to clarify the possible underlying mechanism.

A matrix-assisted laser desorption/ionization imaging mass spectrometric approach to study weight-related changes within thyroid tissue

Obesity is associated with numerous comorbidities along with abnormalities of the endocrine system, more commonly manifesting as dysfunctions of the thyroid gland such as goiter. Changes in weight, especially an increase, could lead to an increase in the incidence of thyroid dysfunction; however, its pathophysiology remains to be elucidated. In the present study, we aimed to interrogate the changes in the protein distribution and abundance between the lean patients and patients with obesity thyroid tissue sections through utilizing this technique. The FFPE-fixed thyroid tissue blocks from the selected cases and controls were identified and targeted for matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) analysis. Patients in the 30 to 75 years age group and undergoing total thyroidectomy for benign thyroid disease were recruited. Patients with thyroid cancers, autoimmune disorders, and other inflammatory conditions were excluded from the study. The selected patients were divided into two groups according to their BMIs: lean (BMI < 25) and obese (BMI > 35). An initial trial set was used as a pilot study for the optimization of the MALDI IMS protocol that was next applied to the selected thyroid tissues. MALDI IMS data from all the samples were aligned and statistical analysis carried out by k-means and linear discriminant analysis (LDA) classification model using principle component analysis (PCA) results were evaluated between the two groups: controls (lean) and cases (obese). Receiver operator characteristic (ROC) curves were alternatively used to calculate the variability of the identified peptides. The discriminating peptides were also independently identified and related to their corresponding proteins by using liquid chromatography and tandem mass spectrometry (LC-MS/MS) analyses. Eight peptides mainly from thyroglobulin were found to be upregulated whereas 10 others were found to be downregulated in the lean compared to the obese group. Through this technique, we will be able to better understand the relationship between the disease entity and obesity.

Liver X Receptor β Related to Tumor Progression and Ribosome Gene Expression in Papillary Thyroid Cancer

BACKGROUND

Intracellular lipid deposition has been reported in thyroid glands in obese animal and human. To understand the regulatory mechanism of lipid metabolism in thyroid cancer, we investigated the expression status of liver X receptor (LXR) and analyzed its clinicopathological characteristics and molecular biological features.

METHODS

Expression status of LXR and its transcriptional targets in human cancers were analyzed using The Cancer Genome Atlas (TCGA). The gene-sets related to high LXRβ expression was investigated by gene set enrichment analysis (GSEA) using Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathways and gene ontology biologic process. Quantitative reverse transcription polymerase chain reaction was performed in thyroid cancer samples using our validation cohort.

RESULTS

In contrast to low expression of LXRα, LXRβ was highly expressed in thyroid cancer compared to the other types of human cancers. High LXRβ expression was correlated with the expression of LXRβ transcriptional targets genes, such as apolipoprotein C1 (APOC1), APOC2, apolipoprotein E (APOE), ATP binding cassette subfamily G member 8 (ABCG8), sterol regulatory elementbinding protein 1c (SREBP1c), and SPOT14. Furthermore, High LXRβ expression group indicated poor clinicopathological characteristics and aggressive molecular biological features independently from the drive mutation status. Mechanistically, high LXRβ expression was coordinately related to ribosome-related gene sets.

CONCLUSION

The mechanistic link between LXRβ and ribosomal activity will be addressed to develop new diagnostic and therapeutic targets in thyroid cancers.

Obese Subjects with Non-Alcoholic Fatty Liver Disease Have a Higher Risk of Thyroid Dysfunction

Objectives The effects of obesity on thyroid function have not been well established. The aim of this study was to investigate the effects of body mass index (BMI) and/or non-alcoholic fatty liver disease (NAFLD) on thyroid function. Methods A retrospective longitudinal analysis was conducted among subjects who underwent comprehensive health check-ups at least four times between 2008 and 2017. Thyroid function was investigated according to BMI or presence of NAFLD at the end of follow-up. The subjects were divided into four groups: control (n = 216), subjects with obese (n = 94), subjects with NAFLD (n = 48), and subjects with obese + NAFLD (n = 93). Obesity was defined as BMI ≥ 25 kg/m2. Results During the mean follow-up of 6.8 years (6.8 ± 1.2 years), 42 of the 451 subjects (9.3%) had subclinical hypothyroidism (SCH) but no subjects developed overt hypothyroidism. In multivariate Cox proportional hazard analysis, after adjustment for age, sex, smoking, and baseline thyroid stimulating hormone level, obese subjects with NAFLD had a higher risk of SCH than the control group. Conclusions The obese subjects with NAFLD had a higher risk for SCH in the future.

Association of adiposity with thyroid nodules: a cross-sectional study of a healthy population in Beijing, China

BACKGROUND

The relationship between thyroid nodules (TNs) and adiposity is controversial. This paper describes a cross-sectional investigation performed to determine the existence of any such relationship. To assess adiposity, body mass index (BMI) and visceral fat area (VFA) were utilized.

METHODS

Between January 1, 2017 and March 3, 2019. Three thousand five hundred thirty four healthy people were examined using thyroid ultrasonography, visceral fat and anthropometric measurements, laboratory tests and questionnaire interview. Binary logistic regression analyses were used.

RESULTS

Of the 3534 healthy subjects, 58.69% (2074/3534) of the subjects had TNs. A total of 55.91% (1976/3534) had BMI ≥ 25 kg/m² and 39.67% (1402/3534) had VFA ≥ 100 cm². After adjustment to address confounders, BMI-based overweight and obesity levels only correlated with higher risk TNs when used as a continuous variable (OR = 1.031, 95% CI: 1.008-1.055, P = 0.008), while VFA was both a continuous variable (OR = 1.003, 95% CI: 1.000-1.005, P = 0.034) and a categorical variable (OR = 1.198, 95% CI: 1.014-1.417, P = 0.034) associated with significantly elevated risk of TNs. Analyzing the subgroups, BMI ≥ 25 kg/m² (OR = 1.500, 95% CI: 1.110-2.026, P = 0.008) was significantly correlated with TN risk in individuals with TG ≥ 1.7 mmol/L. VFA ≥ 100 cm² correlated with the TN risk irrespective of age (< 50 years: OR = 1.374, 95% CI: 1.109-1.703, P = 0.004; ≥ 50 years: OR = 1.367, 95% CI: 1.063-1.759, P = 0.015) and in the following subgroups: women (OR = 4.575, 95% CI: 2.558-8.181, P = 0.000), FBG ≥ 6.1 mmol/L (OR = 1.522, 95% CI: 1.048-2.209, P = 0.027), and TG ≥ 1.7 mmol/L (OR = 1.414, 95% CI: 1.088-1.838, P = 0.010).

CONCLUSIONS

Adiposity correlates with TNs. To assess TN risk in Chinese individuals, VFA is better than BMI.

Relationship between metabolic syndrome and thyroid nodules and thyroid volume in an adult population

PURPOSE

The effects of metabolic syndrome (MetS) on thyroid nodules (TN) and thyroid volume (TV), especially the related gender and age disparities, are controversial. In this study, we aimed to assess the relationships between MetS and TN and TV in an adult population.

METHODS

This cross-sectional study was performed in an adult population in Tianjin. A total of 2606 subjects were enrolled. TV and TN were measured by thyroid ultrasonography. Blood samples were collected to measure biochemical and metabolic parameters.

RESULTS

The prevalence of TN was significantly higher in the MetS (+) group than in the MetS (-) group (P < 0.0001). MetS was independently associated with increased TN risk (OR: 1.24, 95% CI: 1.01-1.51). When stratified by gender, MetS was associated with higher prevalence of TN in males (OR: 1.38, 95% CI: 1.05-1.81) compared with females (OR: 1.02, 95% CI: 0.75-1.39). However, the interaction effect of gender and MetS on TN was not statistically significant (P for interaction = 0.94). MetS was associated with the greater risks of TN in both the <60-year-old group (OR: 1.32, 95% CI: 1.05-1.68) and the ≥60-year-old group (OR: 1.84, 95% CI: 1.24-2.73), while the OR value was significantly higher in the elderly group (P for interaction = 0.03). Additionally, TV was significantly higher in subjects with TN (β = 1.94, P < 0.0001) and MetS (β = 0.94, P = 0.0037).

CONCLUSIONS

This study suggested positive relationships between MetS and an increased risk of TN and enlarged TV. Elderly people (≥60 years old) with MetS were associated with a higher risk of TN than younger people (<60 years old). The effect of MetS on TN was not significantly affected by gender.

CASE FINDING FOR HYPOTHYROIDISM SHOULD INCLUDE TYPE 2 DIABETES AND METABOLIC SYNDROME PATIENTS: A LATIN AMERICAN THYROID SOCIETY (LATS) POSITION STATEMENT

OBJECTIVE

Latin American Thyroid Society (LATS) Hypothyroidism Clinical Practice Guidelines recommend case finding of hypothyroid patients in multiple and different situations that agree with other Society guidelines. However, the detection of hypothyroidism in type 2 diabetes mellitus (T2DM) or metabolic syndrome (MetS) patients is not mentioned in particular. In the recent years, several basic and epidemiologic studies have appeared showing that a lower thyroid function and MetS/T2DM are associated. Hence, the aim of this review is to manifest the LATS position on the diagnosis of hypothyroidism in both MetS and T2DM patients.

METHODS

A search was made in PubMed using the following terms: "hypothyroidism" AND "diabetes" OR "metabolic syndrome." The most relevant studies describing the prevalence and complications due to hypothyroidism in both MetS and T2DM patients were selected.

RESULTS

The current document reviews new information from studies that have shown that the prevalence of hypothyroidism is higher in T2DM patients (odds ratio [OR], 3.45; 95% confidence interval [CI], 2.5 to 4.7) and that diabetic complications are more prevalent in subclinical hypothyroidism (ScH). The incidence of T2DM is 1.09-fold higher with each doubling of thyroid-stimulating hormone (TSH) mIU/L (95% CI, 1.06 to 1.12), and the incidence of prediabetes increases 15% (hazard ratio, 1.15; 95% CI, 1.04 to 1.26) in patients with TSH >5 mIU/L. Similarly, MetS is more prevalent in ScH compared to euthyroid individuals (OR, 1.31; 95% CI, 1.08 to 1.60).

CONCLUSION

Thyroid function is affected in MetS and T2DM, and hypothyroidism is more common in these patients. Diabetic complications are more frequent in ScH patients. Therefore, LATS now recommends aggressive case finding of hypothyroidism in both MetS and T2DM patients.

ABBREVIATIONS

CI = confidence interval; GLUT4 = glucose transporter 4; HOMA-IR = homeostatic model assessment for insulin resistance; HR = hazard ratio; LATS = Latin American Thyroid Society; MetS = metabolic syndrome; OR = odds ratio; ScH = subclinical hypothyroidism; T2DM = type 2 diabetes mellitus; T3 = triiodothyronine; T4 = thyroxine; TSH = thyroid-stimulating hormone.

ER stress contributes to high-fat diet-induced decrease of thyroglobulin and hypothyroidism

Recent studies revealed the emerging role of excess uptake of lipids in the development of hypothyroidism. However, the underlying mechanism is largely unknown. We investigated the effect of high-fat diet (HFD) on thyroid function and the role of endoplasmic reticulum (ER) in HFD-induced hypothyroidism. Male Sprague-Dawley rats were fed with HFD or control diet for 18 wk. HFD rats showed an impaired thyroid function, with decreased thyroglobulin (Tg) level. We found the ER stress was triggered in HFD rat thyroid glands and palmitate-treated thyrocytes. Luminal swelling of ER in thyroid epithelial cells of HFD rats was also observed. The rate of Tg degradation increased in palmitate-treated thyrocytes. In addition, applying 4-phenyl butyric acid to alleviate ER stress in HFD rats improved the decrease of Tg and thyroid function. Withdrawal of the HFD improved thyroid function . In conclusion, we demonstrate that ER stress mediates the HFD-induced hypothyroidism, probably by impairing the production of Tg, and attenuation of ER stress improves thyroid function. Our study provides the understanding of how HFD induces hypothyroidism.

Beneficial effects of thyroid hormone on adipose inflammation and insulin sensitivity of obese Wistar rats

Thyroid hormones play an important role in glucose metabolism and there is evidence of increased prevalence of thyroid dysfunction in obese and diabetic patients. This study aimed at evaluating the thyroid function and the effects of the triiodothyronine (T3) treatment on glycemia control, insulin sensitivity and subclinical inflammation in cafeteria‐diet‐induced obesity in rats. Obesity was induced in male Wistar rats by offering a cafeteria diet and a subset of the obese rats was treated with T3 (1.5 μg per 100 g of body weight) for a 28‐day period. The pituitary‐thyroid axis was evaluated by molecular and biochemical parameters. Cytokine content was measured in the serum as well as in the mesenteric and epididymal white adipose tissue. Obese rats exhibited impairment of glycemia control, increased content of inflammatory cytokines in mesenteric white adipose tissue, decreased serum thyrotropin (TSH) concentration and increased sodium/iodide symporter (NIS) and TSH receptor (TSHR) protein content in thyroid gland. T3 treatment improved insulin sensitivity, glucose tolerance, and reduced inflammatory cytokine content in mesenteric white adipose tissue. In the thyroid gland NIS, TSHR, and thyroperoxidase (TPO) content were reduced while thyroglobulin (TG) content was increased by T3. The thyrotrophic response to negative feedback exerted by T3 was preserved in obese rats. The present data reinforce the beneficial effects of T3 treatment of obese rats on the improvement of insulin sensitivity and on the negative modulation of inflammatory cytokine expression in adipose tissue. Moreover, we have evidenced that the pituitary‐thyroid axis is affected in obese rats, as illustrated by the impaired TSH secretion.

Key pathway and gene alterations in the gastric mucosa associated with obesity and obesity-related diabetes

BACKGROUND AND OBJECTIVE

The stomach plays an important role in obesity and obesity-related diabetes; yet, little is known about key pathways in the gastric mucosa associated with obesity and diabetes.

METHODS

We performed gene microarray and real time-polymerase chain reaction (RT-PCR) on gut mucosa samples from control subjects (CON), patients with simple obesity (OB), and patients with obesity and comorbid diabetes (OD) (n = 3 per group). Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were used to predict the functional significance of differentially expressed genes.

RESULTS

In total, 262 genes were upregulated and 265 genes were downregulated in the OB group whereas 1756 genes were upregulated and 1053 genes were downregulated in the OD group compared with the CON group. Of these, 23 were co-regulated in both comparisons. Seven differentially expressed genes were validated by RT-PCR (NRIP3, L1CAM, TPO, P2RY1, OR8A1, ADAMTS19, and ASIC3). A functional analysis revealed that genes differentially expressed between the OB or OD and CON groups played crucial roles in metabolic, T cell, and G-protein coupled receptor biological processes, and primarily participated in the PI3K-Akt and AGE-RAGE signaling pathways.

CONCLUSIONS

Obesity and obesity-related diabetes are associated with important gene expression and pathway alterations in the stomach.

A High-Fat Diet Rich in Saturated and Mono-Unsaturated Fatty Acids Induces Disturbance of Thyroid Lipid Profile and Hypothyroxinemia in Male Rats

SCOPE

Increasing evidence has shown that the disturbance of lipid metabolism might make a possible contribution to the pathogenesis of organ dysfunction, including thyroid, yet it is unknown whether excess intake of dietary fat interferes in thyroid lipid profile. We investigate the effects of dietary fat toward the thyroid lipid profile and thyroid function.

METHODS AND RESULTS

Male Sprague-Dawley rats are fed with high-fat diet (HFD) rich in saturated and mono-unsaturated fatty acids or chow diet for 18 weeks. LC-MS analysis of thyroid shows that total free fatty acids (FFAs) content is significantly higher in HFD rats. The concentration of highly saturated triglycerides significantly increases in HFD rats, whereas the polyunsaturated triglyceride significantly decreases, indicating the decrease in unsaturation in the HFD group. Significant increase of lysophosphatidylcholines (LPC) is observed in HFD rats. Thyroid function tests show hypothyroxinemia (total thyroxine [TT₄ ] and free thyroxine [FT₄ ]) in HFD rats, and elevated thyrotropin (TSH) concentration. The HFD rats also show decreased thyroid uptake of iodine.

CONCLUSION

Excess intake of dietary fat induces disturbance of thyroid lipid profile and hypothyroxinemia, indicating thyroid dysfunction. We speculate that it may provide a new prospect in understanding the pathogenesis of hypothyroidism.

Palmitic Acid Downregulates Thyroglobulin (Tg), Sodium Iodide Symporter (NIS), and Thyroperoxidase (TPO) in Human Primary Thyrocytes: A Potential Mechanism by Which Lipotoxicity Affects Thyroid?

Our previous studies suggested that the thyroid might be a target organ affected by lipotoxicity, which might be partially related to the increasing prevalence of subclinical hypothyroidism. However, the underlying molecular mechanism is not yet clearly established. This study aimed to assess the effect of palmitic acid stimulation on thyrocyte function. Upon palmitic acid stimulation, intracellular contents of lipids, as well as the expression and activity of three key molecules in thyroid hormone synthesis (i.e., thyroglobulin, sodium iodide symporter, and thyroperoxidase), were determined in human primary thyrocytes. The contents of BODIPY® FL C16 (the fluorescently labeled palmitic acid analogue) entering into the thyrocytes were gradually increased with time extending. Accordingly, the intracellular accumulation of both triglyceride and free fatty acids increased in dose- and time-dependent manners. The effect of palmitic acid stimulation on thyroid hormone synthesis was then determined. Both the mRNA and protein levels of thyroglobulin, sodium iodide symporter, and thyroperoxidase were decreased following palmitic acid stimulation. Consistently, upon palmitic acid stimulation, the secreted thyroglobulin levels in supernatants, ¹³¹I uptake, and extracellular thyroperoxidase activity were all decreased in a dose-dependent manner. Our results demonstrated that upon palmitic acid stimulation, the expressions of the key molecules (thyroglobulin, sodium iodide symporter, and thyroperoxidase) were reduced and their activities were suppressed, which might lead to impaired thyroid hormone synthesis.

Oncogenes, mitochondrial metabolism, and quality control in differentiated thyroid cancer

Thyroid cancer is one of the most common malignancies of endocrine organs, and its incidence rate has increased steadily over the past several decades. Most differentiated thyroid tumors derived from thyroid epithelial cells exhibit slow-growing cancers, and patients with these tumors can achieve a good prognosis with surgical removal and radioiodine treatment. However, a small proportion of patients present with advanced thyroid cancer and are unusually resistant to current drug treatment modalities. Thyroid tumorigenesis is a complex process that is regulated by the activation of oncogenes, inactivation of tumor suppressors, and alterations in programmed cell death. Mitochondria play an essential role during tumor formation, progression, and metastasis of thyroid cancer. Recent studies have successfully observed the mitochondrial etiology of thyroid carcinogenesis. This review focuses on the recent progress in understanding the molecular mechanisms of thyroid cancer relating to altered mitochondrial metabolism.

Metabolic syndrome is associated with an increased incidence of subclinical hypothyroidism - A Cohort Study

Prior cross-sectional analyses have demonstrated an association between subclinical hypothyroidism and metabolic syndrome and selected components. However, the temporal relation between metabolic syndrome and declining thyroid function remains unclear. In a prospective study, an unselected cohort of 66,822 participants with and without metabolic syndrome were followed. A proportional hazards regression model was used to estimate hazard ratios (HRs) and 95% CIs for hypothyroidism. Exploratory analyses for the relation between components of metabolic syndrome and declining thyroid function were also undertaken. During an average follow-up of 4.2 years, the incident rates for subclinical hypothyroidism were substantially higher in participants who began the study with metabolic syndrome compared with metabolically normal controls. After controlling for risk factors, patients with metabolic syndrome were at a 21% excess risk of developing subclinical hypothyroidism (adjusted HR 1.21; 95% CI 1.03–1.42). When individual components were analyzed, an increased risk of subclinical hypothyroidism was associated with high blood pressure (1.24; 1.04–1.48) and high serum triglycerides (1.18; 1.00–1.39), with a trend of increasing risk as participants had additional more components. Individuals with metabolic syndrome are at a greater risk for developing subclinical hypothyroidism, while its mechanisms and temporal consequences of this observation remain to be determined.

Exogenous iodide ameliorates perchlorate-induced thyroid phenotypes in threespine stickleback

Perchlorate is a ubiquitous environmental contaminant that has widespread endocrine disrupting effects in vertebrates, including threespine stickleback (Gasterosteus aculeatus). The target of perchlorate is thyroid tissue where it induces changes in the organization, activation, and morphology of thyroid follicles and surrounding tissues. To test the hypothesis that some phenotypes of perchlorate toxicity are not mediated by thyroid hormone, we chronically exposed stickleback beginning at fertilization to perchlorate (10, 30, 100ppm) or control water with and without supplementation of either iodide or thyroxine (T₄). Stickleback were sampled across a one-year timespan to identify potential differences in responses to treatment combinations before and after sexual maturation. We found that most thyroid histomorphological phenotypes induced by perchlorate (follicle proliferation, reduced follicle area (adults only), colloid depletion, thyrocyte hypertrophy (subadults only)) were significantly ameliorated by exogenous iodide supplementation. In contrast, treatment with exogenous T₄ did not correct any of the thyroid-specific histopathologies induced by perchlorate. Whole-body thyroid hormone concentrations were not significantly affected by perchlorate exposure; however, supplementation with iodide and T₄ significantly increased T₄ concentrations. This study also revealed an increased erythrocyte area in the thyroid region of perchlorate-exposed adults, while lipid droplet number increased in perchlorate-exposed subadults. Increased erythrocyte area was ameliorated by both iodide and T₄, while neither supplement was able to correct lipid droplet number. Our finding on lipid droplets indicates that exposure to perchlorate in early development may have obesogenic effects.

Factors Associated with the Prevalence of Thyroid Nodules and Goiter in Middle-Aged Euthyroid Subjects

The aim of the present study was to determine associations of thyroid hormone levels and different metabolic parameters and anthropometric measurements with volume of nodular and nonnodular thyroid as well as with prevalence of goiter and thyroid nodules in middle-aged euthyroid subjects. Methods. The study consisted of 317 euthyroid subjects aged 48-49 from the Kaunas Cardiovascular Risk Cohort study. Thyroid-stimulating hormone (TSH), free thyroxine (FT4), and antithyroid peroxidase antibody (ATPO) levels, as well as anthropometric and metabolic parameters and smoking information, were evaluated. Results. In subjects with and without thyroid nodules, thyroid volume correlated with components of metabolic syndrome, body mass index (BMI), smoking, and TSH levels. In the nonnodular thyroid group, thyroid volume was also positively related to serum insulin and HOMA-IR, whereas a negative correlation between thyroid volume and leptin was identified in the nodular thyroid group. The goiter was identified in 12.3% of subjects. Female gender, thyroid nodules, smoking, BMI, and levels of TSH were independent predictors for goiter. Thyroid nodules were found in 31.2% of participants. Female gender, higher TSH levels, and thyroid volume were independent risk factors for thyroid nodules. Conclusions. Female gender, thyroid nodules, smoking, BMI, and TSH levels were identified as potential predictors of goiter. Female gender, TSH levels, and thyroid volume predicted the presence of thyroid nodules.

Implications of oncocytic change in papillary thyroid cancer

OBJECTIVE

Although the presence of oncocytic change in less than 75% of a tumour is not considered to indicate oncocytic variants of papillary thyroid carcinoma (PTC), we frequently observe partial oncocytic change, especially in obese PTC patients. Thus, we sought to investigate the relationship between the presence of oncocytic change of PTC and its prognosis.

DESIGN, SETTING AND PARTICIPANTS

We retrospectively studied 142 patients with PTC who had undergone surgery between 2000 and 2005, and re-evaluated their PTC slides to record the proportion of oncocytic change in 10% increments from 0% to 100%.

MAJOR OUTCOME MEASURE

We analysed the relationship between the proportion of oncocytic change and clinicopathological prognostic factors.

RESULTS

Oncocytic change was found in 45·8% (65/142) of PTC patients. The proportion of patients with oncocytic change was higher in obese patients than in lean patients and showed a significant correlation with the BMI (r = 0·195, P = 0·020). The PTC patients with oncocytic change showed a higher recurrence rate than PTC patients without oncocytic change (30·8% vs 11·7%, respectively; P = 0·005). The presence of oncocytic change in PTC patients was associated with a shorter disease-free survival in a Kaplan-Meier analysis after a mean follow-up of 8·9 years.

CONCLUSION

The patients with PTC with oncocytic change presented with a higher recurrence rate and were more likely to be obese. These findings suggest that presence of oncocytic change is a poor prognostic factor in PTC patients, even if the oncocytic change involves less than 75% of a tumour.

Inhibition of STAT3 activity delays obesity-induced thyroid carcinogenesis in a mouse model

Compelling epidemiologic studies indicate that obesity is a risk factor for many human cancers, including thyroid cancer. In recent decades, the incidence of thyroid cancer has dramatically increased along with a marked rise in obesity prevalence. We previously demonstrated that a high fat diet (HFD) effectively induced the obese phenotype in a mouse model of thyroid cancer (Thrb(PV/PV)Pten(+/-) mice). Moreover, HFD activates the STAT3 signal pathway to promote more aggressive tumor phenotypes. The aim of the present study was to evaluate the effect of S3I-201, a specific inhibitor of STAT3 activity, on HFD-induced aggressive cancer progression in the mouse model of thyroid cancer. WT and Thrb(PV/PV)Pten(+/-) mice were treated with HFD together with S3I-201 or vehicle-only as controls. We assessed the effects of S3I-201 on HFD-induced thyroid cancer progression, the leptin-JAK2-STAT3 signaling pathway, and key regulators of epithelial-mesenchymal transition (EMT). S3I-201 effectively inhibited HFD-induced aberrant activation of STAT3 and its downstream targets to markedly inhibit thyroid tumor growth and to prolong survival. Decreased protein levels of cyclins D1 and B1, cyclin dependent kinase 4 (CDK4), CDK6, and phosphorylated retinoblastoma protein led to the inhibition of tumor cell proliferation in S3I-201-treated Thrb(PV/PV)Pten(+/-) mice. Reduced occurrence of vascular invasion and blocking of anaplasia and lung metastasis in thyroid tumors of S3I-201-treated Thrb(PV/PV)Pten(+/-) mice were mediated via decreased expression of vimentin and matrix metalloproteinases, two key effectors of EMT. The present findings suggest that inhibition of the STAT3 activity would be a novel treatment strategy for obesity-induced thyroid cancer.

Association Between Obesity and BRAFV600E Mutation Status in Patients with Papillary Thyroid Cancer

BACKGROUND

The prevalence of papillary thyroid cancer (PTC) is thought to be related to obesity, which affects the prognosis for PTC patients. However, the mechanisms implicated in the relationship between obesity and PTC is a matter for debate. In this study, we aimed to gain insight into the relationship between obesity and the clinicopathological features of PTC, including the BRAFV600E mutation.

METHODS

The medical records of 1121 PTC patients were reviewed and the relationships between anthropometric factors, biochemical parameters, and clinicopathological parameters, including BRAFV600E mutation status, were analyzed.

RESULTS

Body mass index (BMI) showed a strong association with advanced TNM stage (p < 0.001) and BRAFV600E mutation status (p = 0.008). We also found that BRAFV600E (+) patients had a higher body weight (p = 0.024) and a higher BMI (p = 0.003) than patients with BRAFV600E (-) PTC. In addition, BRAFV600E (+) PTC patients had a significantly higher incidence of extrathyroidal extension (p = 0.025) and more advanced T, N, TNM stage (p < 0.001) than BRAFV600E (-) PTC patients. Consistent with this observation, female BRAFV600E (+) PTC patients had a higher BMI (p = 0.011) and more aggressive tumor behaviors than female BRAFV600E (-) PTC patients. In multivariate analysis, BMI was persistently associated with BRAFV600E mutation in the entire cohort (odds ratio [OR] 1.387; 95 % CI 1.036-1.859; p = 0.028) and in the female subcohort (OR 1.221; 95 % CI 1.014-1.631; p = 0.046).

CONCLUSION

The positive association between BMI and BRAFV600E supports the hypothesis that excessive bodyweight influences tumor progression.