Subclinical Hypothyroidism and Low-Normal Thyroid Function Are Associated With Nonalcoholic Steatohepatitis and Fibrosis

Hypothyroidism phenotypes, clinical characteristics, and factors associated with nodular thyroid disease in patients with hypothyroidism in Southern Ghana: a 6-year retrospective study

BACKGROUND

This study aimed to describe the frequency of hypothyroidism phenotypes, clinical characteristics, and factors associated with nodular thyroid among hypothyroid patients at the University of Ghana Hospital in southern Ghana.

METHODS

This study was a 6-year hospital-based retrospective study that extracted data from 221 patients with hypothyroidism from the archival records of the University of Ghana Hospital using a checklist. These include socio-demography (age, gender, marital status, residential status, educational level), lifestyle variables (anthropometry, smoking status, alcohol intake), and co-morbidities, as well as ultrasound imaging findings of the thyroid. Serum thyroid hormone levels were used to classify hypothyroidism phenotypes. Bivariate and multivariate logistic regression analyses were performed to identify factors associated with nodular thyroid disease.

RESULT

The frequency of primary, subclinical, and secondary hypothyroidism was 81.4%, 16.3%, and 2.3%, respectively. Fatigue [120(54.3%)], heavy menstrual loss [54/160(33.8%)], and cold intolerance [73(33.0%)], were predominant symptoms while 54/57 (94.7%) were overweight/obese, 23/32 (71.9%) had dyslipidaemia whereas 7/34 (20.6%) had hypertension. The odds of developing nodular thyroid disease were 2.11 times higher (95% CI: 1.07-4.17; p = 0.032) in males than in females.

CONCLUSION

Our results provide insight into the frequency of hypothyroidism phenotypes, clinical characteristics, and factors associated with nodular thyroid, emphasizing male gender as an independent predictor of nodular thyroid disease. Our findings also emphasize the need for lifestyle adjustment as a mitigating strategy in the management of hypothyroidism. However, prospective studies are required to confirm the findings or investigate the histological characteristics of thyroid nodules in patients with hypothyroidism.

Thyroid function and hepatic fibrosis/cirrhosis: a two-sample Mendelian randomization study

Background

Evidence on the relationship between thyroid function and hepatic fibrosis/cirrhosis are still unclear, with inconsistent conclusions. This Mendelian randomization (MR) study aimed to investigate the potential causal association between thyroid function and hepatic fibrosis/cirrhosis in order to provide new insights for improving prevention and control strategies for this disease.

Methods

Genome-wide association study (GWAS) data on exposures, which included hyperthyroidism, hypothyroidism, and thyroid-stimulating hormone (TSH), were extracted from the MRC Integrative Epidemiology Unit (MRC-IEU) (https://gwas.mrcieu.ac.uk/), and GWAS data for outcomes, including hepatic fibrosis/cirrhosis and chitinase-3-like protein 1 (CHI3L1), were obtained from the FinnGen consortium (https://www.finngen.fi/fi). Inverse variance weighted (IVW), weighted median, and MR-Egger methods were utilized to examine the causal association between thyroid function and the risk of hepatic fibrosis/cirrhosis. Cochran's Q test was used to assess the heterogeneity of instrumental variables (IVs), while MR-PRESSO and leave-one-out analyses were conducted for sensitivity analysis.

Results

IVW estimates suggested that hypothyroidism had a potential causal association with higher odds of hepatic fibrosis/cirrhosis (OR = 1.247, 95% CI: 1.087-1.431). Leave-one-out results indicated that this potential causal relationship was relatively robust. In addition, we assessed the causal association between hypothyroidism and hepatic fibrosis/cirrhosis before and after removal of outliers with heterogeneity. After removing the outliers, the association was still significant (OR = 1.266, 95% CI: 1.082-1.482, P = 0.0046).

Conclusion

Patients with hypothyroidism may have a higher risk of hepatic fibrosis/cirrhosis, and this finding may provide some references for the early screening and prevention of the disease. However, further studies are needed to explore the specific mechanisms by which hypothyroidism influences hepatic fibrosis/cirrhosis.

The Oxidoreductase Retinol Saturase in Thyroid Gland Is Regulated by Hypothyroidism and Iodide Overload and Its Deletion Impairs Metabolic Homeostasis in Mice

Aims: Thyroid hormones (TH) are major regulators of cell differentiation, growth, and metabolic rate. TH synthesis in the thyroid gland requires high amounts of H2O2 to oxidize iodide for the iodination of thyroglobulin (TG). Retinol Saturase (RetSat) is an oxidoreductase implicated in dihydroretinol formation and cellular sensitivity toward peroxides and ferroptosis. RetSat is highly expressed in metabolically active organs where it regulates lipid metabolism and the production of reactive oxygen species. Due to the high expression of RetSat in the thyroid gland and its role in peroxide sensitivity, we investigated the regulation and function of RetSat in the thyroid gland in appropriate mouse models. Results: RetSat is strongly expressed in thyrocytes, induced by hypothyroidism, and decreased by iodide overload in mice. Thyrocyte-specific deletion of RetSat increased circulating thyroid-stimulating hormone levels, altered thyroid morphology, and disturbed metabolic homeostasis in a diet- and sex-dependent manner without major effects on the concentrations of circulating TH. Moreover, deletion of RetSat increased TG protein levels but lowered TG iodination upon iodide overload. In cultured thyrocytes, acute RetSat depletion altered the expression of genes involved in TH biosynthesis and the response to endoplasmic reticulum stress. Innovation: This is the first report that specifically dissects the regulation and function of the oxidoreductase RetSat in the thyroid gland. Conclusion: Deletion of RetSat in thyrocytes induces compensatory feedback mechanisms to maintain TH homeostasis in mice. We conclude that RetSat in the thyroid gland is required for TH biosynthesis and secretion and metabolic homeostasis in mice. Antioxid. Redox Signal. 42, 463-479.

Liver fibrotic burden across the spectrum of hypothyroidism

BACKGROUND

Data regarding the prevalence of hepatic fibrotic burden across the spectrum of hypothyroidism are scarce. Hence, we aimed to evaluate the prevalence of liver fibrotic burden across the spectrum of hypothyroidism.

METHODS

30,091 individuals who attended a Health Management Centre between 2019 and 2021 were cross-sectionally analyzed. Participants were categorized as having strict-normal thyroid function, low-normal thyroid function, subclinical hypothyroidism, and overt hypothyroidism. Hepatic fibrosis was assessed by vibration-controlled transient elastography (VCTE). Significant and advanced fibrosis were defined as liver stiffness measurement in VCTE of 8.1-9.6 and 9.7-13.5 kPa, respectively.

RESULTS

Among both men and women, low-normal thyroid function group, subclinical hypothyroidism group, and overt hypothyroidism group all have more liver fibrosis present, including mild fibrosis, significant fibrosis, advanced fibrosis, and cirrhosis, than the strict-normal thyroid function group. The low-normal thyroid function group have the similar liver fibrotic burden to the subclinical hypothyroidism group. The highest liver fibrotic burden was noted in the overt hypothyroidism group. Both significant and advanced liver fibrosis were significantly associated with low-normal thyroid function, subclinical hypothyroidism, and overt hypothyroidism in both men and women.

CONCLUSIONS

Liver fibrotic burden are highly prevalent in subjects with overt hypothyroidism. Moreover, fibrotic burden increased across the spectrum of hypothyroidism even within the low normal thyroid function. These results suggested that screening for liver fibrosis in patients with hypothyroidism is necessary.

Association of Sensitivity to Thyroid Hormones and Non-Alcoholic Fatty Liver Disease and the Severity of Liver Fibrosis in Euthyroid Adults: A Retrospective Study

Purpose

The relationship between non-alcoholic fatty liver disease (NAFLD) and thyroid function is controversial. A mild acquired thyroid hormone resistance may exist and explain these contradictions. This study aims to investigate the associations of thyroid hormone sensitivity with NAFLD and the severity of liver fibrosis in euthyroid populations.

Patients and Methods

Twenty-nine thousand three hundred and eighty-six adult subjects were recruited from the medical examination center of the Beijing Chao-Yang Hospital. Free triiodothyronine (FT3)/free thyroxine (FT4), thyroid feedback quartile-based index for FT4 (TFQIFT4) and for FT3 (TFQIFT3), thyroid stimulating hormone index (TSHI), thyrotropin thyroxine resistance index (TT4RI), and thyrotropin triiodothyronine resistance index (TT3RI) were calculated. Logistic regression analysis was used to analyze the associations of thyroid hormone sensitivity indices with the risks of NAFLD and related metabolic disorders. The correlation between thyroid hormone sensitivity and the severity of liver fibrosis evaluated by noninvasive fibrosis indices was analyzed through ordinal logistic regression.

Results

Euthyroid adults with NAFLD had elevated levels of serum FT3 and FT4, reduced TSH, and impaired sensitivity to thyroid hormones. Compared with participants in the first quartile group, the risk of NAFLD was higher in the fourth quartile of TFQIFT3 (OR 1.25, 95% CI 1.13-1.39, P < 0.001) and FT3/FT4 (OR 1.45, 95% CI 1.32-1.60, P < 0.001) after adjusting for metabolic confounders. Among NAFLD patients, higher FT3/FT4 positively correlated with increased severity of liver fibrosis, with ORs per SD of 10.80 (95% CI 4.12-28.53, P < 0.001) for aminotransferase-to-platelet ratio index, 4.74 (95% CI 1.56-14.38, P = 0.006) for NAFLD fibrosis score and 3.21 (95% CI 1.02-10.08, P = 0.046) for fibrosis-4 index.

Conclusion

Impaired central sensitivity to FT3 and higher FT3/FT4 were associated with increased risks of NAFLD and related metabolic disorders. In patients with NAFLD, higher FT3/FT4 correlated with its progression to liver fibrosis. These findings might provide novel insight into the monitoring and evaluation of the risk of NAFLD and the severity of liver fibrosis.

Thyroid hormone receptor-β analogues for the treatment of metabolic dysfunction-associated steatohepatitis (MASH)

The association between suboptimal thyroid function ((sub)clinical hypothyroidism or low-normal thyroid function) and the metabolic syndrome and MASLD (metabolic dysfunction-associated steatotic liver disease) has been clearly established. Furthermore, in MASLD, intracellular thyroid hormone concentrations are low and the activation of the thyroid hormone receptor (THR) is reduced. Administration of thyroid hormone has been shown to reduce liver triglycerides by stimulating fatty acid disposal through lipophagy and beta-oxidation, and to lower LDL-cholesterol. As thyroid hormone exerts its effects in many different organs, including the heart and bone, several drug candidates have been developed as selective thyromimetics for the THR-β nuclear receptor with potent and liver-targeted activity. Importantly, these compounds have reduced affinity for the THR-α nuclear receptor and tissue distribution profiles that differ from endogenous thyroid hormones, thereby reducing unwanted cardiovascular side effects. The most advanced compound, resmetirom, is an oral drug that demonstrated, in a large phase III trial in patients with MASH (metabolic dysfunction-associated steatohepatitis), the ability to reduce liver fat, decrease aminotransferase levels and improve atherogenic dyslipidaemia with a good tolerability profile. This translated into histological improvement that led to accelerated approval of this drug for active fibrotic steatohepatitis, a milestone achievement as a first MASH drug.

Actions of thyroid hormones and thyromimetics on the liver

Thyroid hormones (triiodothyronine and thyroxine) are pivotal for metabolic balance in the liver and entire body. Dysregulation of the hypothalamus-pituitary-thyroid axis can contribute to hepatic metabolic disturbances, affecting lipid metabolism, glucose regulation and protein synthesis. In addition, reductions in circulating and intrahepatic thyroid hormone concentrations increase the risk of metabolic dysfunction-associated steatotic liver disease by inducing lipotoxicity, inflammation and fibrosis. Amelioration of hepatic metabolic disease by thyroid hormones in preclinical and clinical studies has spurred the development of thyromimetics that target THRB (the predominant thyroid hormone receptor isoform in the liver) and/or the liver itself to provide more selective activation of hepatic thyroid hormone-regulated metabolic pathways while reducing thyrotoxic side effects in tissues that predominantly express THRA such as the heart and bone. Resmetirom, a liver and THRB-selective thyromimetic, recently became the first FDA-approved drug for metabolic dysfunction-associated steatohepatitis (MASH). Thus, a better understanding of the metabolic actions of thyroid hormones and thyromimetics in the liver is timely and clinically relevant. Here, we describe the roles of thyroid hormones in normal liver function and pathogenesis of MASH, as well as some potential clinical issues that might arise when treating patients with MASH with thyroid hormone supplementation or thyromimetics.

Thyroid hormone and the Liver

It is known that thyroid hormone can regulate hepatic metabolic pathways including cholesterol, de novo lipogenesis, fatty acid oxidation, lipophagy, and carbohydrate metabolism. Thyroid hormone action is mediated by the thyroid hormone receptor (THR) isoforms and their coregulators, and THRβ is the main isoform expressed in the liver. Dysregulation of thyroid hormone levels, as seen in hypothyroidism, has been associated with dyslipidemia and metabolic dysfunction-associated fatty liver disease. Given the beneficial effects of thyroid hormone in liver metabolism and the advances illuminating the use of thyroid hormone analogs such as resmetirom as therapeutic agents in the treatment of metabolic dysfunction-associated fatty liver disease, this review aims to further explore the relationship between TH, the liver, and metabolic dysfunction-associated fatty liver disease. Herein, we summarize the current clinical therapies and highlight future areas of research.

Biochemical basis and therapeutic potential of mitochondrial uncoupling in cardiometabolic syndrome

Mild uncoupling of oxidative phosphorylation is an intrinsic property of all mitochondria, allowing for adjustments in cellular energy metabolism to maintain metabolic homeostasis. Small molecule uncouplers have been extensively studied for their potential to increase metabolic rate, and recent research has focused on developing safe and effective mitochondrial uncoupling agents for the treatment of obesity and cardiometabolic syndrome (CMS). Here, we provide a brief overview of CMS and cover the recent mechanisms by which chemical uncouplers regulate CMS-associated risk-factors and comorbidities, including dyslipidemia, insulin resistance, steatotic liver disease, type 2 diabetes, and atherosclerosis. Additionally, we review the current landscape of uncoupling agents, focusing on repurposed FDA-approved drugs and compounds in advanced preclinical or early-stage clinical development. Lastly, we discuss recent molecular insights by which chemical uncouplers enhance cellular energy expenditure, highlighting their potential as a new addition to the current CMS drug landscape, and outline several limitations that need to be addressed before these agents can successfully be introduced into clinical practice.

NASH triggers cardiometabolic HFpEF in aging mice

Both heart failure with preserved ejection fraction (HFpEF) and non-alcoholic fatty liver disease (NAFLD) develop due to metabolic dysregulation, has similar risk factors (e.g., insulin resistance, systemic inflammation) and are unresolved clinical challenges. Therefore, the potential link between the two disease is important to study. We aimed to evaluate whether NASH is an independent factor of cardiac dysfunction and to investigate the age dependent effects of NASH on cardiac function. C57Bl/6 J middle aged (10 months old) and aged mice (24 months old) were fed either control or choline deficient (CDAA) diet for 8 weeks. Before termination, echocardiography was performed. Upon termination, organ samples were isolated for histological and molecular analysis. CDAA diet led to the development of NASH in both age groups, without inducing weight gain, allowing to study the direct effect of NASH on cardiac function. Mice with NASH developed hepatomegaly, fibrosis, and inflammation. Aged animals had increased heart weight. Conventional echocardiography revealed normal systolic function in all cohorts, while increased left ventricular volumes in aged mice. Two-dimensional speckle tracking echocardiography showed subtle systolic and diastolic deterioration in aged mice with NASH. Histologic analyses of cardiac samples showed increased cross-sectional area, pronounced fibrosis and Col1a1 gene expression, and elevated intracardiac CD68+ macrophage count with increased Il1b expression. Conventional echocardiography failed to reveal subtle change in myocardial function; however, 2D speckle tracking echocardiography was able to identify diastolic deterioration. NASH had greater impact on aged animals resulting in cardiac hypertrophy, fibrosis, and inflammation.

EASL-EASD-EASO Clinical Practice Guidelines on the management of metabolic dysfunction-associated steatotic liver disease (MASLD)

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously termed non-alcoholic fatty liver disease (NAFLD), is defined as steatotic liver disease (SLD) in the presence of one or more cardiometabolic risk factor(s) and the absence of harmful alcohol intake. The spectrum of MASLD includes steatosis, metabolic dysfunction-associated steatohepatitis (MASH, previously NASH), fibrosis, cirrhosis and MASH-related hepatocellular carcinoma (HCC). This joint EASL-EASD-EASO guideline provides an update on definitions, prevention, screening, diagnosis and treatment for MASLD. Case-finding strategies for MASLD with liver fibrosis, using non-invasive tests, should be applied in individuals with cardiometabolic risk factors, abnormal liver enzymes, and/or radiological signs of hepatic steatosis, particularly in the presence of type 2 diabetes (T2D) or obesity with additional metabolic risk factor(s). A stepwise approach using blood-based scores (such as FIB-4) and, sequentially, imaging techniques (such as transient elastography) is suitable to rule-out/in advanced fibrosis, which is predictive of liver-related outcomes. In adults with MASLD, lifestyle modification - including weight loss, dietary changes, physical exercise and discouraging alcohol consumption - as well as optimal management of comorbidities - including use of incretin-based therapies (e.g. semaglutide, tirzepatide) for T2D or obesity, if indicated - is advised. Bariatric surgery is also an option in individuals with MASLD and obesity. If locally approved and dependent on the label, adults with non-cirrhotic MASH and significant liver fibrosis (stage ≥2) should be considered for a MASH-targeted treatment with resmetirom, which demonstrated histological effectiveness on steatohepatitis and fibrosis with an acceptable safety and tolerability profile. No MASH-targeted pharmacotherapy can currently be recommended for the cirrhotic stage. Management of MASH-related cirrhosis includes adaptations of metabolic drugs, nutritional counselling, surveillance for portal hypertension and HCC, as well as liver transplantation in decompensated cirrhosis.

Use of transient elastography for hepatic steatosis and fibrosis evaluation in patients with subclinical hypothyroidism

OBJECTIVE

To evaluate the association between subclinical hypothyroidism and hepatic steatosis and fibrosis using the noninvasive diagnostic methods transient hepatic elastography (TE) and controlled attenuation parameter (CAP) in patients with subclinical hypothyroidism.

SUBJECTS AND METHODS

This was a cross-sectional study including women with confirmed spontaneous subclinical hypothyroidism and an age- and body mass index (BMI)-matched control group without thyroid disease or circulating antithyroperoxidase (anti-TPO) antibodies. Exclusion criteria were age > 65 years, thyroid-stimulating hormone (TSH) > 10.0 mIUI/L, BMI ≥ 35 kg/m2, diabetes, or other chronic liver diseases. Liver stiffness was classified according to TE values (in kPa) and ranged from absence of fibrosis (F0) to advanced fibrosis (F3). Hepatic steatosis was classified according to CAP values (in dB/m) and ranged from low-grade (S1) to advanced (S3) steatosis.

RESULTS

Of 68 women enrolled, 27 were included in the subclinical hypothyroidism group and 41 in the control group. Advanced steatosis (S3) was more frequent in the subclinical hypothyroidism group (25.9% versus 7.3%, respectively, p = 0.034). Circulating anti-TPO was an independent factor associated with advanced steatosis (odds ratio 9.5, 95% confidence interval 1.3-68.3). In multiple linear regression analysis, TE values (which evaluated fibrosis) correlated negatively with free thyroxine levels.

CONCLUSION

The results of this study strengthen the hypothesis that hepatic steatosis is associated with autoimmune (positive anti-TPO) subclinical hypothyroidism, independently from BMI. However, subclinical hypothyroidism alone does not appear to be associated with a significantly increased risk of hepatic fibrosis.

Association between primary hypothyroidism and metabolic dysfunction-associated steatotic liver disease: an updated meta-analysis

OBJECTIVE

Epidemiological studies have reported an association between primary hypothyroidism and metabolic dysfunction-associated steatotic liver disease (MASLD). However, the magnitude of the risk and whether this risk changes with the severity of MASLD remains uncertain. We performed a meta-analysis of observational studies to quantify the magnitude of the association between primary hypothyroidism and the risk of MASLD.

DESIGN

We systematically searched PubMed, Scopus and Web of Science from database inception to 31 January 2024, using predefined keywords to identify observational studies in which MASLD was diagnosed by liver biopsy, imaging or International Classification of Diseases codes. A meta-analysis was performed using random-effects modelling.

RESULTS

We identified 24 cross-sectional and 4 longitudinal studies with aggregate data on ~76.5 million individuals. Primary hypothyroidism (defined as levothyroxine replacement treatment, subclinical hypothyroidism or overt hypothyroidism) was associated with an increased risk of prevalent MASLD (n=24 studies; random-effects OR 1.43, 95% CI 1.23 to 1.66; I2=89%). Hypothyroidism was also associated with a substantially higher risk of metabolic dysfunction-associated steatohepatitis or advanced fibrosis (n=5 studies; random-effects OR 2.84, 95% CI 2.07 to 3.90; I2=0%). Meta-analysis of data from four longitudinal studies showed that there was a marginally non-significant association between hypothyroidism and risk of developing MASLD over a median 4.5-year follow-up (random-effects HR 1.39, 95% CI 0.98 to 1.97; I2=85%). Sensitivity analyses did not modify these findings. The funnel plot did not reveal any significant publication bias.

CONCLUSION

This large and updated meta-analysis provides evidence that primary hypothyroidism is significantly associated with both an increased presence of and histological severity of MASLD.

Impact of peripheral thyroid hormone balance on liver fat: insights from the NutriAct trial

OBJECTIVE

Hypothyroidism has been proposed as a potential contributor to steatotic liver disease (SLD), but existing data shows conflicting results in euthyroid subjects. Therefore, we investigated the association between thyroid function and intrahepatic lipids (IHLs) during a 36-month randomized controlled trial evaluating a diet known to reduce liver fat.

DESIGN

502 eligible subjects (aged 50-80 years, ≥1 risk factor for unhealthy aging) were randomly assigned to either follow a diet rich in unsaturated fatty acids, plant protein, and fiber (intervention group, IG), or dietary recommendations of the German Nutrition Society (control group, CG).

METHODS

Serum levels of thyroid hormones (THs) as well as IHLs, defined via magnetic resonance spectroscopy, were measured within an euthyroid subgroup without significant alcohol consumption at baseline (n = 332) and after 12 months (n = 243). A ratio of T3/T4 was used to assess whole-body deiodinase activity. Estimates of glucose and lipid metabolism were analyzed.

RESULTS

Only fT3 and T3/T4 ratios showed a significant positive correlation with IHL at baseline. We observed a significant decline in fT3, T3, fT3/fT4 ratio, and T3/T4 ratio in CG and IG after 12 months without significant differences between groups. TSH, fT4, and T4 remained stable. A larger improvement of IHL during dietary intervention was seen in those subjects with a lower decline in T3 concentrations.

CONCLUSIONS

Altered TH balance indicates a possible compensatory upregulation of whole-body TH activity in subjects with increased liver fat. This might be also relevant during the improvement of hepatic steatosis.

Association between thyroid function and nonalcoholic fatty liver disease: a dose-response meta-analysis

Background

Thyroid hormones (THs) have been found that it is closely associated with the onset and progression of non-alcoholic fatty liver disease (NAFLD). However, the current study could not verify the intrinsic relationship between thyroid hormones and NAFLD, which requires further research.

Methods

The searches of studies reported both TH level in serum and NAFLD were performed in PubMed, Web of Science, Cochrane Library, and Embase databases. We combined an overall meta-analysis with a dose-response meta-analysis to assess the correlation and dose-response relationship between thyroid function levels and the risk of NAFLD.

Results

Overall, 10 studies were included with a total of 38,425 individuals. We found that the non-linear dose-response model showed that for every 1 ng/dL increase in FT4, the risk of NAFLD was reduced by 10.56% (p=0.003). The odds ratios (ORs) for NAFLD with high free triiodothyronine (FT3) exposure compared to those with low FT3 were 1.580 (95% CI 1.370 to 1.830, I2 = 0.0%, p<0.001) in the overall meta-analysis. The continuous variable meta-analysis indicated that individuals with high levels of TSH (SMD=1.32, 95% CI 0.660 to 1.970, p<0.001) had significantly higher levels of liver fibrosis than those with low levels.

Conclusions

Our findings only validate that there is a correlation between the occurrence of NAFLD and abnormal levels of THs, and it is expected that more observational studies will still be conducted in the future to further demonstrate the relationship between thyroid hormones and NAFLD.

Trial registration

Registered number in PROSPERO: CRD42023405052.

EASL-EASD-EASO Clinical Practice Guidelines on the Management of Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously termed non-alcoholic fatty liver disease (NAFLD), is defined as steatotic liver disease (SLD) in the presence of one or more cardiometabolic risk factor(s) and the absence of harmful alcohol intake. The spectrum of MASLD includes steatosis, metabolic dysfunction-associated steatohepatitis (MASH, previously NASH), fibrosis, cirrhosis and MASH-related hepatocellular carcinoma (HCC). This joint EASL-EASD-EASO guideline provides an update on definitions, prevention, screening, diagnosis and treatment for MASLD. Case-finding strategies for MASLD with liver fibrosis, using non-invasive tests, should be applied in individuals with cardiometabolic risk factors, abnormal liver enzymes, and/or radiological signs of hepatic steatosis, particularly in the presence of type 2 diabetes (T2D) or obesity with additional metabolic risk factor(s). A stepwise approach using blood-based scores (such as FIB-4) and, sequentially, imaging techniques (such as transient elastography) is suitable to rule-out/in advanced fibrosis, which is predictive of liver-related outcomes. In adults with MASLD, lifestyle modification - including weight loss, dietary changes, physical exercise and discouraging alcohol consumption - as well as optimal management of comorbidities - including use of incretin-based therapies (e.g. semaglutide, tirzepatide) for T2D or obesity, if indicated - is advised. Bariatric surgery is also an option in individuals with MASLD and obesity. If locally approved and dependent on the label, adults with non-cirrhotic MASH and significant liver fibrosis (stage ≥2) should be considered for a MASH-targeted treatment with resmetirom, which demonstrated histological effectiveness on steatohepatitis and fibrosis with an acceptable safety and tolerability profile. No MASH-targeted pharmacotherapy can currently be recommended for the cirrhotic stage. Management of MASH-related cirrhosis includes adaptations of metabolic drugs, nutritional counselling, surveillance for portal hypertension and HCC, as well as liver transplantation in decompensated cirrhosis.

Intrahepatic hypothyroidism in MASLD: Role of liver-specific thyromimetics including resmetirom

BACKGROUND AND AIMS

Thyroid hormones are important regulators of hepatic lipid homeostasis and whole-body energy expenditure. Recent evidence suggests that euthyroid individuals with metabolic dysfunction-associated steatohepatitis (MASH) develop intrahepatic hypothyroidism that promotes progression of MASH.

METHODS

A literature search was performed with Medline (PubMed), Scopus and Google Scholar electronic databases from inception till March 2024, using the following keywords: hypothyroidism and nonalcoholic fatty liver disease; MASLD and thyroid function; intrahepatic hypothyroidism; TRβ agonists; and resmetirom. Relevant studies were extracted that described pathogenesis of MASH in the context of thyroid functions.

RESULTS

In euthyroid individuals with MASH, there is decreased conversion of prohormone thyroxine (T4) to bioactive tri-iodothyronine (T3) and increased conversion of T4 to inactive metabolite reverse T3 (rT3). Consequently, reduced levels of T3 results in impaired intrahepatic TRβ signaling, a state of intrahepatic hypothyroidism, which promotes progression of MASH. Hepatic TRβ activation leads to metabolically beneficial effects in the liver including mitochondrial fatty acid uptake and β-oxidation, mitochondrial biogenesis, increasing surface low-density lipoprotein (LDL) receptor density and lowering of circulatory LDL-cholesterol. In recent years, selective thyroid hormone mimetics that exhibit TRβ-selective binding and liver-selective uptake have been designed. Resmetirom, a liver-specific thyromimetic, improves intrahepatic TRβ signaling and in clinical trials significantly improved liver inflammation, fibrosis and lipid profile in patients with MASH.

CONCLUSIONS

In euthyroid individuals with MASH, development of intrahepatic hypothyroidism results in further progression of the disease. In clinical trials, resmetirom treatment results in a significant improvement in steatosis, inflammation and fibrosis and is the first drug approved by the US Food and Drug Administration (FDA) for the treatment of noncirrhotic MASH with moderate to advanced fibrosis.

From liver to hormones: The endocrine consequences of cirrhosis

Hepatocrinology explores the intricate relationship between liver function and the endocrine system. Chronic liver diseases such as liver cirrhosis can cause endocrine disorders due to toxin accumulation and protein synthesis disruption. Despite its importance, assessing endocrine issues in cirrhotic patients is frequently neglected. This article provides a comprehensive review of the epidemiology, pathophysiology, diagnosis, and treatment of endocrine disturbances in liver cirrhosis. The review was conducted using the PubMed/Medline, EMBASE, and Scielo databases, encompassing 172 articles. Liver cirrhosis is associated with endocrine disturbances, including diabetes, hypoglycemia, sarcopenia, thyroid dysfunction, hypogonadotropic hypogonadism, bone disease, adrenal insufficiency, growth hormone dysfunction, and secondary hyperaldosteronism. The optimal tools for diagnosing diabetes and detecting hypoglycemia are the oral glucose tolerance test and continuous glucose monitoring system, respectively. Sarcopenia can be assessed through imaging and functional tests, while other endocrine disorders are evaluated using hormonal assays and imaging studies. Treatment options include metformin, glucagon-like peptide-1 analogs, sodium-glucose co-transporter-2 inhibitors, and insulin, which are effective and safe for diabetes control. Established standards are followed for managing hypoglycemia, and hormone replacement therapy is often necessary for other endocrine dysfunctions. Liver transplantation can address some of these problems.

Targeting nuclear receptors for NASH/MASH: From bench to bedside

The onset of metabolic dysfunction-associated steatohepatitis (MASH) or non-alcoholic steatohepatitis (NASH) represents a tipping point leading to liver injury and subsequent hepatic complications in the natural progression of what is now termed metabolic dysfunction-associated steatotic liver diseases (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD). With no pharmacological treatment currently available for MASH/NASH, the race is on to develop drugs targeting multiple facets of hepatic metabolism, inflammation, and pro-fibrotic events, which are major drivers of MASH. Nuclear receptors (NRs) regulate genomic transcription upon binding to lipophilic ligands and govern multiple aspects of liver metabolism and inflammation. Ligands of NRs may include hormones, lipids, bile acids, and synthetic ligands, which upon binding to NRs regulate the transcriptional activities of target genes. NR ligands are presently the most promising drug candidates expected to receive approval from the United States Food and Drug Administration as a pharmacological treatment for MASH. This review aims to cover the current understanding of NRs, including nuclear hormone receptors, non-steroid hormone receptors, circadian NRs, and orphan NRs, which are currently undergoing clinical trials for MASH treatment, along with NRs that have shown promising results in preclinical studies.

Thyroid function, adipokines and mitokines in metabolic dysfunction-associated steatohepatitis: A multi-centre biopsy-based observational study

BACKGROUND AND AIMS

Thyroid axis is currently under investigation as a therapeutic target in metabolic dysfunction-associated steatotic liver disease (MASLD). Thyroid function was examined herein in the full spectrum of disease.

METHODS

Subjects were recruited and had liver biopsies in two Gastroenterology-Hepatology Clinics (Greece and Australia) and one Bariatric-Metabolic Surgery Clinic (Italy). The main working sample was n = 677 subjects with MASLD after excluding subjects with abnormal free thyroxine levels. Participants were classified according to thyroid-stimulating hormone (TSH) standard criteria: Subclinical hyperthyroidism (<0.4 uIU/mL); Euthyroidism with relatively low (0.4 to <2.5 uIU/mL); euthyroidism with relatively high (2.5-4.0 uIU/mL); subclinical hypothyroidism (>4 uIU/mL).

RESULTS

TSH as a continuous variable was positively associated with significant fibrosis (F ≥ 2), metabolic dysfunction-associated steatohepatitis (MASH) and at-risk MASH. Subclinical hypothyroidism was associated with fibrosis F ≥ 2 (odds ratio [OR] = 3.47, 95% confident interval [CI] [1.50, 8.05], p = .02), MASH (OR = 3.44, 95% CI [1.48, 7.98] p = .001) and at-risk MASH (OR = 3.88, 95% CI [1.76, 8.55], p = .001), before and after controlling for adiposity, central obesity, and insulin resistance. When leptin, adiponectin, or growth differentiation factor-15 were examined as moderators, significance was lost. Sex-specific analysis revealed a strong association between TSH and the presence of significant fibrosis among women, eliminated only when adipokines/mitokines were adjusted for. Restricted cubic spline analysis revealed associations between TSH and liver outcomes (p-values < .01) with inflection points for fibrosis F ≥ 2 being 2.49, for MASH being 2.67 and for at-risk MASH being 6.96.

CONCLUSIONS

These observations provide support for studies on the administration of thyroid hormone in MASLD therapeutics for subclinical hypothyroidism and liver-specific thyroid receptor agonists for subjects across the TSH continuum.

Resmetirom: Finally, the Light at the End of the NASH Tunnel?

Nonalcoholic steatohepatitis (NASH) is a double composite word that was first coined in 1980 by Ludwig and Colleagues [...]

Association between low-normal thyroid function and advanced liver fibrosis in metabolic dysfunction-associated fatty liver disease patients: a retrospective cohort study

Background

Recent studies have found that thyroid function may be associated with the occurrence and development of advanced liver fibrosis in patients with metabolic dysfunction-associated fatty liver disease (MAFLD). However, the majority of such research has consisted of cross-sectional studies. This retrospective cohort study aimed to investigate the effect of low-normal thyroid function on advanced liver fibrosis in MAFLD patients over a 5-year period.

Methods

This retrospective cohort study enrolled 825 outpatients and inpatients with MAFLD who attended the Third Affiliated Hospital of Sun Yat-sen University (Guangzhou, China) between January 2011 and December 2018. Based on plasma thyroid hormone and thyroid-stimulating hormone levels, these patients were divided into two groups, namely a low-normal thyroid function group and a strict-normal thyroid function group. The fibrosis-4 score was used to assess advanced liver fibrosis. A chi-square test was conducted to compare the occurrence of advanced fibrosis between the groups.

Results

Among the 825 MAFLD patients, 117 and 708 were defined as having low-normal thyroid function and strict-normal thyroid function, respectively. Follow-up data were available for 767 patients (93.0%) during a 5-year period. Eight (7.5%) MAFLD patients with low-normal thyroid function and 26 (3.9%) with strict-normal thyroid function developed advanced liver fibrosis and the cumulative incidence was not significantly different (P = 0.163). Stratification analysis showed that the lean MAFLD patients (body mass index ≤ 23 kg/m2) with low-normal thyroid function had a higher risk of advanced liver fibrosis than the lean MAFLD patients with strict-normal thyroid function (P < 0.05).

Conclusion

Low-normal thyroid function is associated with advanced liver fibrosis among lean MAFLD patients.

Tuning of liver circadian transcriptome rhythms by thyroid hormone state in male mice

Thyroid hormones (THs) are important regulators of systemic energy metabolism. In the liver, they stimulate lipid and cholesterol turnover and increase systemic energy bioavailability. It is still unknown how the TH state interacts with the circadian clock, another important regulator of energy metabolism. We addressed this question using a mouse model of hypothyroidism and performed circadian analyses. Low TH levels decreased locomotor activity, food intake, and body temperature mostly in the active phase. Concurrently, liver transcriptome profiling showed only subtle effects compared to elevated TH conditions. Comparative circadian transcriptome profiling revealed alterations in mesor, amplitude, and phase of transcript levels in the livers of low-TH mice. Genes associated with cholesterol uptake, biosynthesis, and bile acid secretion showed reduced mesor. Increased and decreased cholesterol levels in the serum and liver were identified, respectively. Combining data from low- and high-TH conditions allowed the identification of 516 genes with mesor changes as molecular markers of the liver TH state. We explored these genes and created an expression panel that assesses liver TH state in a time-of-day dependent manner. Our findings suggest that the liver has a low TH action under physiological conditions. Circadian profiling reveals genes as potential markers of liver TH state.

Thyroid hormone receptor alpha modulates fibrogenesis in hepatic stellate cells

OBJECTIVE

Progressive hepatic fibrosis can be considered the final stage of chronic liver disease. Hepatic stellate cells (HSC) play a central role in liver fibrogenesis. Thyroid hormones (TH, e.g. thyroxine; T4 and triiodothyronine; T3) significantly affect development, growth, cell differentiation and metabolism through activation of TH receptor α and/or β (TRα/β). Here, we evaluated the influence of TH in hepatic fibrogenesis.

DESIGN

Human liver tissue was obtained from explanted livers following transplantation. TRα-deficient (TRα-KO) and wild-type (WT) mice were fed a control or a profibrogenic methionine-choline deficient (MCD) diet. Liver tissue was assessed by qRT-PCR for fibrogenic gene expression. In vitro, HSC were treated with TGFβ in the presence or absence of T3. HSC with stable TRα knockdown and TRα deficient mouse embryonic fibroblasts (MEF) were used to determine receptor-specific function. Activation of HSC and MEF was assessed using the wound healing assay, Western blotting, and qRT-PCR.

RESULTS

TRα and TRβ expression is downregulated in the liver during hepatic fibrogenesis in humans and mice. TRα represents the dominant isoform in HSC. In vitro, T3 blunted TGFβ-induced expression of fibrogenic genes in HSC and abrogated wound healing by modulating TGFβ signalling, which depended on TRα presence. In vivo, TRα-KO enhanced MCD diet-induced liver fibrogenesis.

CONCLUSION

These observations indicate that TH action in non-parenchymal cells is highly relevant. The interaction of TRα with TH regulates the phenotype of HSC via the TGFβ signalling pathway. Thus, the TH-TR axis may be a valuable target for future therapy of liver fibrosis.

MASLD treatment-a shift in the paradigm is imminent

MASLD prevalence is growing towards the leading cause of end-stage liver disease. Up to today, the most effective treatment is weight loss. Weight loss interventions are moving from lifestyle changes to bariatric surgery or endoscopy, and, more recently, to a new wave of anti-obesity drugs that can compete with bariatric surgery. Liver-targeted therapy is a necessity for those patients who already present liver fibrosis. The field is moving fast, and in the near future, we will testify to a disruptive change in MASLD treatment, similar to the paradigm-shift that occurred for hepatitis C almost one decade ago with direct antiviral agents.

Endocrine aspects of metabolic dysfunction-associated steatotic liver disease (MASLD): Beyond insulin resistance

While the association of metabolic dysfunction-associated steatotic liver disease (MASLD) with obesity and insulin resistance is widely appreciated, there are a host of complex interactions between the liver and other endocrine axes. While it can be difficult to definitively distinguish direct causal relationships and those attributable to increased adipocyte mass, there is substantial evidence of the direct and indirect effects of endocrine dysregulation on the severity of MASLD, with strong evidence that low levels of growth hormone, sex hormones, and thyroid hormone promote the development and progression of disease. The impact of steroid hormones, e.g. cortisol and dehydroepiandrosterone, and adipokines is much more divergent. Thoughtful assessment, based on individual risk factors and findings, and management of non-insulin endocrine axes is essential in the evaluation and management of MASLD. Multiple therapeutic options have emerged that leverage various endocrine axes to reduce the fibroinflammatory cascade in MASH.

Lack of thyroid hormone receptor beta is not detrimental for non-alcoholic steatohepatitis progression

Agonists for thyroid hormone receptor β (TRβ) show promise in preclinical studies and clinical trials to improve non-alcoholic fatty liver disease. A recent study on human livers, however, revealed reduced TRβ expression in non-alcoholic steatohepatitis (NASH), indicating a developing thyroid hormone resistance, which could constitute a major obstacle for those agonists. Using a rapid NASH paradigm combining choline-deficient high-fat diet and thermoneutrality, we confirm that TRβ declines during disease progression in mice similar to humans. Contrary to expectations, mice lacking TRβ showed less liver fibrosis, and NASH marker genes were not elevated. Conversely, increasing TRβ expression in wild-type NASH mice using liver-targeted gene therapy did not improve histology, gene expression, or metabolic parameters, indicating that TRβ receptor levels are of minor relevance for NASH development and progression in our model, and suggest that liver-rather than isoform-specificity might be more relevant for NASH treatment with thyroid hormone receptor agonists.

Ameliorative Effects of Thunbergia erecta L. Leaves Against the Initiation of Hepatocarcinogenesis Induced by Diethylnitrosamine in the Rat Model

Thunbergia erecta L. contains cytotoxic and liver-protective compounds. Thunbergia erecta L. leaves were macerated in 70% aqueous ethanol, then fractionated with ethyl acetate (9.3 g) and butanol (12.7 g), and attenuated Den-induced liver cancer in a Wistar rat experimental model. Ethyl acetate and butanol fractions were chromatographed using column chromatography and solid-phase extraction (SPE); Vicenin-II (1), kaempferol (2), biochanin A, sissotrin 7-O-β-glucopyranoside (3), gentianose (4), acacetin 7-O-β-glucopyranoside (5), apigenin 7-O-β-glucopyranoside (6), and rosmarinic acid (7) were extracted, and their structures were determined using NMR spectroscopy and ESI-mass spectrometry. Sixty rats were divided into six groups (ten each): control group, Den group, doxorubicin/Den-treated group, butanol fraction/Den-treated group, and isolated acacetin 7-O-β-glucopyranoside/Den-treated group. The liver enzymes and proinflammatory biomarkers were used to estimate the liver function. In addition, liver tissues were collected for analysis of oxidative stress markers, gene expression, and histopathology. There is a significant increase in the levels of liver enzymes, AFP, and TNF-ἁ. This was conveyed by a significant increase of IL-1 and caspase-3, elevation of MDA and reduction of GSH, and suppression of Bcl2 and elevation of Bax expression. All parameters in butanol, ethyl acetate fractions, and isolated acacetin 7-O-β-glucopyranoside (major constituents) of T. erecta L. were significantly improved to values close to those of the control group.

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.

Vitamin D alleviates hypothyroidism associated liver dysfunction: Histological and biochemical evidence

There is a complex correlation between thyroid hormones (THs) and liver function. Hypothyroidism as a failure of the thyroid gland to produce adequate thyroid hormones to fulfill the metabolic requirements of the body, may perturb liver structure and function. Emerging evidence suggests the protective effects of vitamin D against liver damage. Herein, this study aimed to investigate the role of vitamin D in hypothyroidism-associated liver injury. Forty male Wistar rats were classified into 4 groups: control, hypothyroid (Hypo) group received 0.05% PTU, Hypo- Vitamin D groups were given 100 and 500 IU/kg vitamin D orally via gavage for 6 weeks. Serum level of liver function including alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) were measured. Malondialdehyde (MDA) level, superoxide dismutase (SOD) enzyme activity, and total thiol content were measured as oxidative stress indicators in the liver tissue. Furthermore, to estimate liver tissue fibrosis, Masson's trichrome staining was done. Our findings showed that hypothyroidism-induced liver fibrosis was associated with increased levels of ALT, AST and ALP. Though, vitamin D administration could significantly reduce the ALT, AST and ALP in the serum and suppress the accumulation of collagen fibers. Moreover, the activity of SOD and total thiol content was notably reduced, while the MDA content was significantly increased in the PTU- induced hypothyroid rats compared to the control group. Nonetheless, treatment with vitamin D improved mentioned oxidative stress markers in the Hypo-vitamin D groups. In conclusion, vitamin D due to its potential antioxidant and anti-fibrotic properties could be effective in the decrease of hypothyroidism-associated liver injury.

The Interrelation Between Hypothyroidism and Non-alcoholic Fatty Liver Disease, a Cross-sectional Study

Background

Thyroid hormones play an important role in the regulation of diverse metabolic processes and might play a crucial role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, their association remains controversial. Therefore, our aim is to clarify whether overt or subclinical hypothyroidism was associated with NAFLD.

Methods

This cross-sectional study included 60 participants with a new diagnosis of hypothyroidism and 30 age- and gender-matched healthy participants with thyroid-stimulating hormone (TSH) level <4.5 mIU/L. Anthropometric measurements, laboratory parameters, plasma fibroblast growth factor 21 (FGF21), and hepatic steatosis diagnosed via controlled attenuation parameter (CAP) using transient elastography between the hypothyroid groups and control group were analyzed.

Results

Participants with hypothyroidism displayed significantly higher serum aspartate aminotransferase, alanine aminotransferase, gamma glutamyl transferase, total cholestrol, triglycerides, low-density lipoprotein cholesterol, TSH, hemoglobin A1c, fasting insulin, and homeostatic model assessment of insulin resistance (HOMA-IR) but significantly lower serum albumin, high-density lipoprotein cholesterol, and free thyroxine levels than the control group (P = <0.001). The CAP values were significantly higher in participants with overt and subclinical hypothyroidism than the control group (P = <0.001). The only significant independent predictors of steatosis in our study were free T4, body mass index, and HOMA-IR after using multivariate logistic regression. The mean serum FGF21 levels were increased in hypothyroid participants with hepatic steatosis than those without hepatic steatosis (126.9 ± 272.6) pg/ml vs. (106.8 ± 138.7) pg/ml, P = 0.8). Receiver operating characteristic (ROC) curve showed that FGF21 was not a significant marker for hepatic steatosis in hypothyroid participants (area under curve (AUC) = 0.44, P = 0.54).

Conclusion

Individuals with subclinical or overt hypothyroidism were more likely to have NAFLD than those with normal thyroid function. Serum FGF21 levels were increased in hypothyroid individuals and its role as a marker of hepatic steatosis in hypothyroid individuals needs further assessment.

The association between thyroid hormones and MAFLD is mediated by obesity and metabolic disorders and varies among MAFLD subtypes

BACKGROUND

Thyroid hormone (TH) disorders increased the risk of metabolic dysfunction-associated fatty liver disease (MAFLD).

AIM

To assess whether the association between TH and MAFLD is mediated via metabolic dysfunctions and varies among MAFLD subtypes (diabetes-MAFLD, overweight/obesity-MAFLD, metabolic disorders-MAFLD).

METHODS

A total of 18,427 participants (661 diabetes-MAFLD, 3,600 overweight/obesity-MAFLD, 691 metabolic disorder-MAFLD cases, 13,475 non-MAFLD controls) from a Chinese hospital were enrolled. Hepatic ultrasound measurements and thyroid function were assessed.

RESULTS

Overweight/obesity mediated the associations of MAFLD with triiodothyronine (T3), free triiodothyronine (FT3), free thyroxine (FT4), and the mediator accounted for 46.43%, 39.69%, and 42.68%, respectively. Metabolic disorder mediated the association of MAFLD with T3, FT3, FT4, thyroid stimulating hormone (TSH), and the mediator accounted for 36.57%, 23.19%, 34,65%, and 60.92%, respectively. Diabetes did not complementary mediate any association between TH and MAFLD. Elevated T3, FT3, TSH and decreased FT4 increased the risk of overweight/obesity-MAFLD, and the odds ratios were 1.59, 1.72, 1.18, and 0.60, respectively (Q4 vs.Q1, false discovery rate (FDR)<0.05). Elevated T3, FT3, and decreased FT4 increased the risk of metabolic disorder-MAFLD, and the odds ratios were 1.45, 1.33, and 0.52, respectively (Q4 vs.Q1, FDR<0.05). No significant association between TH and diabetes-MAFLD was detected.

CONCLUSION

The association between TH and MAFLD is mediated by overweight/obesity and metabolic disorders and varies among MAFLD subtypes.

Causes and risk profiles of mortality among individuals with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the United States and worldwide. Though nonalcoholic fatty liver per se may not be independently associated with an increased risk for all-cause mortality, it is associated with a number of harmful metabolic risk factors, such as type 2 diabetes mellitus, hyperlipidemia, obesity, a sedentary lifestyle, and an unhealthy diet. The fibrosis stage is a predictor of all-cause mortality in NAFLD. Mortality in individuals with NAFLD has been steadily increasing, and the most common cause-specific mortality for NAFLD is cardiovascular disease, followed by extra-hepatic cancer, liver-related mortality, and diabetes. High-risk profiles for mortality in NAFLD include PNPLA3 I148M polymorphism, low thyroid function and hypothyroidism, and sarcopenia. Achieving weight loss through adherence to a high-quality diet and sufficient physical activity is the most important predictor of improvement in NAFLD severity and the benefit of survival. Given the increasing health burden of NAFLD, future studies with more long-term mortality data may demonstrate an independent association between NAFLD and mortality.

Sensitivity to thyroid hormones is associated with advanced fibrosis in euthyroid patients with non-alcoholic fatty liver disease: A cross-sectional study

BACKGROUND AND AIMS

The relationship between thyroid hormone sensitivity and the occurrence of advanced hepatic fibrosis in non-alcoholic fatty liver disease (NAFLD) remains unclear. We aimed to explore the association between sensitivity to thyroid hormones and advanced fibrosis (F3-F4) of NAFLD in patients with biopsy-proven euthyroid NAFLD.

METHODS

In this study, 129 participants with biopsy-proven euthyroid NAFLD were enrolled, all of whom underwent thyroid function tests and liver biopsy. Indicators reflecting the sensitivity to thyroid hormones were also calculated. A logistic regression model was used to evaluate the association between thyroid hormone sensitivity and risk of advanced liver fibrosis.

RESULTS

Among the 129 participants, 40 (31.0%) had advanced fibrosis. Advanced fibrosis was independently associated with TSH, FT3, FT3/FT4, thyrotroph T4 resistance index (TT4RI), TSH index (TSHI), and thyroid feedback quantile-based index (TFQI) (P<0.05), even after adjusting for sex, age, and metabolic factors. The combination of TFQI with age, waist circumference (WC), triglycerides (TGs), and low-density lipoprotein cholesterol (LDL-C) performed best for advanced fibrosis diagnosis.

CONCLUSION

In euthyroid NAFLD patients, higher FT3/FT4, TFQI, TT4RI, and TSHI values were strongly associated with an increased incidence of advanced liver fibrosis. The combination of TFQI with age, WC, TGs, and LDL-C can be used as a predictor for advanced fibrosis in patients with NAFLD.

Nonalcoholic fatty liver disease and non-liver comorbidities

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease characterized by excess fat accumulation in the liver. It is closely associated with metabolic syndrome, and patients with NAFLD often have comorbidities such as obesity, type 2 diabetes mellitus, and dyslipidemia. In addition to liver-related complications, NAFLD has been associated with a range of non-liver comorbidities, including cardiovascular disease, chronic kidney disease, and sleep apnea. Cardiovascular disease is the most common cause of mortality in patients with NAFLD, and patients with NAFLD have a higher risk of developing cardiovascular disease than the general population. Chronic kidney disease is also more common in patients with NAFLD, and the severity of NAFLD is associated with a higher risk of developing chronic kidney disease. Sleep apnea, a disorder characterized by breathing interruptions during sleep, is also more common in patients with NAFLD and is associated with the severity of NAFLD. The presence of non-liver comorbidities in patients with NAFLD has important implications for the management of this disease. Treatment of comorbidities such as obesity, type 2 diabetes mellitus, and dyslipidemia may improve liver-related outcomes in patients with NAFLD. Moreover, treatment of non-liver comorbidities may also improve overall health outcomes in patients with NAFLD. Therefore, clinicians should be aware of the potential for non-liver comorbidities in patients with NAFLD and should consider the management of these comorbidities as part of the overall management of this disease.

Low thyroid function is associated with an increased risk of advanced fibrosis in patients with metabolic dysfunction-associated fatty liver disease

AIMS

Observational studies showed that low thyroid function may perturb liver function. We aimed to evaluate the association of low thyroid function with both metabolic dysfunction-associated fatty liver disease (MAFLD) and advanced hepatic fibrosis.

METHODS

Participants who underwent abdominal ultrasonography and thyroid function test in a Chinese hospital from 2015 to 2021were enrolled. Fibrosis-4 index (FIB-4) > 2.67 and/or non-alcoholic fatty liver disease fibrosis score (NFS) > 0.676 were used to define advanced fibrosis. Descriptive analyses were performed to characterize the epidemiology of MAFLD according to levels of thyroid-stimulating hormone (TSH). The logistic regression model was applied to estimate the association of low thyroid function with MAFLD and advanced fibrosis.

RESULTS

A total of 19,946 participants (52.78% males, mean age: 47.31 years, 27.55% MAFLD) were included, among which 14,789 were strict-normal thyroid function, 4,328 were low-normal thyroid function, 829 were subclinical hypothyroidism. TSH levels were significantly higher in MAFLD patients with a FIB-4 > 2.67 and /or NFS > 0.676 than their counterparts. The logistic regression model adjusted for age and sex showed that low-normal thyroid function increased the risk of MAFLD (odds ratio [OR] = 1.09; 95% confidence interval [CI] 1.01-1.18). Multivariable regression model adjusted for age, sex, body mass index, type 2 diabetes, and hypertension showed low-normal thyroid function increased the risk of advanced fibrosis in patients with MAFLD (FIB-4 > 2.67: OR = 1.41, 95% CI 1.02-1.93; NFS > 0.676: OR = 1.72, 95% CI 1.08-2.72).

CONCLUSION

Elevated TSH concentrations are associated with advanced hepatic fibrosis, even in the euthyroid state.

Potential use of TG68 - A novel thyromimetic - for the treatment of non-alcoholic fatty liver (NAFLD)-associated hepatocarcinogenesis

Introduction

Several lines of evidence suggest that the thyroid hormone signaling pathway is altered in patients with NAFLD and that pharmacological strategies to target the thyroid hormone/thyroid hormone nuclear receptor axis (TH/THR) in the liver may exert beneficial effects. In this study, we investigated the effect of TG68, a novel THRβ agonist, on rat hepatic fat accumulation and NAFLD-associated hepatocarcinogenesis.

Methods

Male rats given a single dose of diethylnitrosamine (DEN) and fed a high fat diet (HFD) were co-treated with different doses of TG68. Systemic and hepatic metabolic parameters, immunohistochemistry and hepatic gene expression were determined to assess the effect of TG68 on THRβ activation.

Results

Irrespectively of the dose, treatment with TG68 led to a significant reduction in liver weight, hepatic steatosis, circulating triglycerides, cholesterol and blood glucose. Importantly, a short exposure to TG68 caused regression of DEN-induced preneoplastic lesions associated with a differentiation program, as evidenced by a loss of neoplastic markers and reacquisition of markers of differentiated hepatocytes. Finally, while an equimolar dose of the THRβ agonist Resmetirom reduced hepatic fat accumulation, it did not exert any antitumorigenic effect.

Discussion

The use of this novel thyromimetic represents a promising therapeutic strategy for the treatment of NAFLD-associated hepatocarcinogenesis.

Clinical value of thyroid related hormones combined with neutrophil to lymphocyte ratio in patients with nonalcoholic fatty liver disease

BACKGROUND

In sufferers with nonalcoholic fatty liver disease (NAFLD), the differences of thyroid associated hormones and neutrophil to lymphocyte ratio (NLR) in different liver pathological groups have been compared.

METHODS

Patients with NAFLD diagnosed by liver biopsy in our hospital from July 2012 to February 2019 were selected. All subjects were divided into nonalcoholic steatohepatitis (NASH) team and non-NASH group, no/mild fibrosis group (F0-1) and significant fibrosis group (F2-4). The differences of thyroid related hormones and NLR in these groups were in contrast, respectively. For the TSH, we conducted further evaluation based on gender.

RESULTS

The TSH and NLR in NASH patients were significantly higher than non-NASH patients, but there was no considerable difference in free triiodothyronine (FT3) and free thyroxine (FT4) between the 2 groups. In the gender-based subgroup analysis, the variations of TSH between the 2 groups were nonetheless statistically significant (P < .05). The TSH and NLR in the significant fibrosis group were higher than these in the non/mild liver fibrosis group, and the differences were statistically significant (P < .05), but there was no large difference in FT3 and FT4 between the 2 groups (P > .05). In addition, in the gender-based subgroup analysis and further multivariable analysis, the variations of TSH between the 2 groups were still statistically significant (P < .05).

CONCLUSIONS

In this study, we found that serum thyroid stimulating hormone (TSH) and neutrophil to lymphocyte ratio (NLR) were closely associated to the severity of NAFLD, suggesting that this simple available laboratory index may additionally be incorporated into the future noninvasive diagnostic scoring model to predict the incidence of NASH and the degree of fibrosis.

Diagnostic and therapeutic strategies for non-alcoholic fatty liver disease

The global incidence rate of non-alcoholic fatty liver disease (NAFLD) is approximately 25%. With the global increase in obesity and its associated metabolic syndromes, NAFLD has become an important cause of chronic liver disease in many countries. Despite recent advances in pathogenesis, diagnosis, and therapeutics, there are still challenges in its treatment. In this review, we briefly describe diagnostic methods, therapeutic targets, and drugs related to NAFLD. In particular, we focus on evaluating carbohydrate and lipid metabolism, lipotoxicity, cell death, inflammation, and fibrosis as potential therapeutic targets for NAFLD. We also summarized the clinical research progress in terms of drug development and combination therapy, thereby providing references for NAFLD drug development.

NAFLD and thyroid function: pathophysiological and therapeutic considerations

Nonalcoholic fatty liver disease (NAFLD) is a worldwide rising challenge because of hepatic, but also extrahepatic, complications. Thyroid hormones are master regulators of energy and lipid homeostasis, and the presence of abnormal thyroid function in NAFLD suggests pathogenic relationships. Specifically, persons with hypothyroidism feature dyslipidemia and lower hepatic β-oxidation, which favors accumulation of triglycerides and lipotoxins, insulin resistance, and subsequently de novo lipogenesis. Recent studies indicate that liver-specific thyroid hormone receptor β agonists are effective for the treatment of NAFLD, likely due to improved lipid homeostasis and mitochondrial respiration, which, in turn, may contribute to a reduced risk of NAFLD progression. Taken together, the possible coexistence of thyroid disease and NAFLD calls for increased awareness and optimized strategies for mutual screening and management.

The Molecular Mechanisms of Liver Fibrosis and Its Potential Therapy in Application

Liver fibrosis results from repeated and persistent liver damage. It can start with hepatocyte injury and advance to inflammation, which recruits and activates additional liver immune cells, leading to the activation of the hepatic stellate cells (HSCs). It is the primary source of myofibroblasts (MFs), which result in collagen synthesis and extracellular matrix protein accumulation. Although there is no FDA and EMA-approved anti-fibrotic drug, antiviral therapy has made remarkable progress in preventing or even reversing the progression of liver fibrosis, but such a strategy remains elusive for patients with viral, alcoholic or nonalcoholic steatosis, genetic or autoimmune liver disease. Due to the complexity of the etiology, combination treatments affecting two or more targets are likely to be required. Here, we review the pathogenic mechanisms of liver fibrosis and signaling pathways involved, as well as various molecular targets for liver fibrosis treatment. The development of efficient drug delivery systems that target different cells in liver fibrosis therapy is also summarized. We highlight promising anti-fibrotic events in clinical trial and preclinical testing, which include small molecules and natural compounds. Last, we discuss the challenges and opportunities in developing anti-fibrotic therapies.

Effect of Liraglutide on Serum TSH Levels in Patients with NAFLD and its Underlying Mechanisms

This study aimed to evaluate the effect of liraglutide on serum thyroid-stimulating hormone (TSH) levels in patients with type 2 diabetes mellitus (T2DM) and explore the underlying mechanisms via bioinformatics analysis. A total of 49 obese/overweight patients with T2DM received liraglutide during outpatient visits or hospitalization in the Department of Endocrinology. Meanwhile, the control group included 49 patients with T2DM but without nonalcoholic fatty liver disease (NAFLD) who were matched for age and sex (baseline from July 2016 to June 2021). Follow-up data on the last use of liraglutide were also retrieved. Age, sex, body mass index (BMI), and duration of diabetes were obtained from the participants' records. All patients were tested for biochemical markers hemoglobin A1c (HbA1c), alanine transaminase, aspartate transaminase, free triiodothyronine, free thyroxine (FT4), and TSH at baseline and follow-up. After adjusting for all factors with a p-value < 0.05, BMI, HbA1c, LDL, FT4, and TSH were identified as significant independent risk factors for NAFLD in the univariate analysis. Following liraglutide therapy (average time 16 months), these patients had significantly lower BMI, HbA1c, and TSH but higher high-density lipoprotein (HDL) levels than those in the baseline data (all p < 0.05), and further subgroup analysis stratified by duration of liraglutide use showed that the test for time trends had statistical differences in BMI and TSH but not in HbA1c and HDL. After the therapy, the NAFLD and NASH groups showed significantly decreased TSH levels after liraglutide therapy compared with the corresponding baseline data. Furthermore, the expression of THRB, which encodes TRβ, was significantly decreased in the NAFLD group, which may explain the thyroid hormone resistance-like manifestation in the clinical findings. In conclusion, liraglutide improves hepatic thyroid hormone resistance in T2DM with NAFLD, and restoration of impaired TRβ expression in NAFLD is a potential mechanism involved in the process of liraglutide therapy.

TSH-SPP1/TRβ-TSH positive feedback loop mediates fat deposition of hepatocyte: Crosstalk between thyroid and liver

AIMS

We conducted this study with two aims: (1) whether TRβ could be damaged by NAFLD, thereby represent thyroid hormone resistance-like manifestation and (2) to analyze the potential role of SPP1 in TH signaling pathway on the process of NAFLD. This study is expected to provide a new perspective on the therapeutic mechanism in the pathological course of NAFLD.

METHODS

A total of 166 patients diagnosed with type 2 diabetes mellitus (T2DM) were enrolled in this study. All patients had a BMI above 24 kg/m2 and were stratified into two groups: NAFLD and Non-NAFLD groups. Ages, gender, BMI, duration of diabetes and biochemical markers were obtained from participants' records. We downloaded the dataset GSE48452 from GEO. The Pathview library was used to make the thyroid hormone signaling pathway visualization. The CIBERSORT algorithm was applied to calculate the infiltrated immune cells in obese NAFLD patients. C57BL/6 mice were randomly selected to constitute the normal control (NC) group and were fed a normal chow diet; the rest of the mice were fed a high-fat diet (HFD). After 12 weeks HFD feeding, the mice were sacrificed by cervical dislocation, and blood samples were collected. Mouse livers were also collected; one part of each liver was fixed in 10% formalin for histological analysis, and the other part was snap-frozen for subsequent molecular analyses. To explore the relationship between SPP1, TRβ and lipid deposition in hepatocytes, HepG2 cells were treated with 50 μ M concentration of PA and/or 20 ng/ml concentration of rh-SPP1 for 48h. In addition, the PC3.1-TRβ plasmid was constructed for further validation in HepG2 cells. We used THP-1 cells to construct an M1 macrophage model in vitro. We then analyzed THP-1 cells treated with various concentrations of PA or TSH.

RESULTS

(1) After adjusting for all factors that appeared P value less than 0.1 in the univariate analysis, BMI, TSH, and FT3 were significant independent risk factors of NAFLD (ORs were 1.218, 1.694, and 2.259, respectively); (2) A further analysis with BMI stratification indiacted that both FT3 and TSH had a significant change between individuals with NAFLD and Non-NAFLD in obesity subgroup; however, there was no statistic difference in over-weight group; (3) Bioinformatics analysis of GSE48452 had shown that several key molecular (including TRβ) of thyroid hormone pathway affected by NAFLD induced transcriptomic changes and the expression levels of SPP1, FABP4 and RPS4Y1 were significantly higher, while the expression levels of PZP and VIL1 were significantly decreased in NAFLD patients(adjusted p < 0.05, |logFC| > 1.0). The CIBERSORT algorithm showed increased M0 and M1, decreased M2 macrophage infiltration in NAFLD with comparison to healthy obese group; (4) After 12 weeks of HFD-feeding, the obesity mice had significantly higher serum TSH and In IHC-stained liver sections of obesity group, the intensity of SPP1 had a significantly increased, while TRβ reduced; (5) In vitro studies have shown SPP1 aggravated lipid deposition in hepatic cells dependent on down-regulating the expression of TRβ and TSH acts to promote secretion of SPP1 in M1 macrophage cells.

CONCLUSIONS

SPP1 secretion induced by M1 macrophage polarization, which may down-regulates TRβ in hepatocytes via paracrine manner, on the one hand, the lipid deposition aggravating in liver, on the other hand, a compensatory increase of TSH in serum. The increased TSH can further lead to the following SPP1 secretion of M1 macrophage. The positive feedback crosstalk between thyroid and liver, may be plays an important role in maintaining and amplifying pathological process of NAFLD.