Crosstalk of hepatocyte nuclear factor 4a and glucocorticoid receptor in the regulation of lipid metabolism in mice fed a high-fat-high-sugar diet

The human glucocorticoid receptor variant rs6190 promotes blood cholesterol and atherosclerosis

Elevated cholesterol poses a significant cardiovascular risk, particularly in older women. The glucocorticoid receptor (GR), a crucial nuclear transcription factor that regulates the metabolism of virtually all major nutrients, harbors a still undefined role in cholesterol regulation. Here, we report that a coding single nucleotide polymorphism (SNP) in the gene encoding the GR, rs6190, associated with increased cholesterol levels in women according to UK Biobank and All Of Us datasets. In SNP-genocopying transgenic mice, we found that the rs6190 SNP enhanced hepatic GR activity to transactivate Pcsk9 and Bhlhe40, negative regulators of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) receptors in liver respectively. Accordingly, in mice the rs6190 SNP was sufficient to elevate circulating cholesterol levels across all lipoprotein fractions and the risk and severity of atherosclerotic lesions on the pro-atherogenic hAPOE*2/*2 background. The SNP effect on atherosclerosis was blocked by in vivo knockdown of Pcsk9 and Bhlhe40 in liver. Remarkably, we found that this mechanism was conserved in human hepatocyte-like cells using CRISPR-engineered, SNP-genocopying human induced pluripotent stem cells (hiPSCs). Taken together, our study leverages a non-rare human variant to uncover a novel GR-dependent mechanism contributing to atherogenic risk, particularly in women.

Disruption of Lipid Profile, Glucose Metabolism, and Leptin Levels following Citalopram Administration and High-Carbohydrate and High-Cholesterol Diet in Mice

INTRODUCTION

Depression therapy has been linked to negative effects on energy metabolism, which can be attributed to various factors, including an ongoing inflammatory process commonly seen in metabolic disorders. Unhealthy lifestyle choices of patients and the impact of antidepressants on body weight and lipid and glucose metabolism also contribute to these metabolic side effects. Although not as pronounced as other psychopharmaceuticals, the increasing use of antidepressants raises concerns about their potential impact on public health. The study aimed to evaluate the short- and long-term effects of the antidepressant citalopram and its long-term combination with a special diet on metabolic parameters in mice.

METHODS

Animals were randomly divided into 5 groups - control, control + special diet, citalopram (10 mg/kg for 35 days), citalopram + special diet (10 mg/kg for 35 days), and citalopram (10 mg/kg for 7 days). After a described time of administration, animals were anesthetized, blood and fat and liver tissues were collected. Biochemical parameters of lipid metabolism (total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides) and glucose were analyzed using spectrophotometry and relevant adipokines and cytokines were evaluated by ELISA.

RESULTS

After a week of application of citalopram, we observed dyslipidemia that persisted even at the end of the 5-week experiment. Furthermore, after 5 weeks of citalopram administration, we observed a significant decrease in body weight gain and decreased leptin levels. Changes in lipid metabolism, higher levels of adipokines leptin and PAI-1 were observed due to the special diet after 5 weeks.

CONCLUSIONS

Our research suggests that the effects of citalopram and a diet on the metabolism of mice can be significant, both in the short term (1 week) and in the long term (5 weeks).

Stress-induced mucin 13 reductions drive intestinal microbiome shifts and despair behaviors

Depression is a prevalent psychological condition with limited treatment options. While its etiology is multifactorial, both chronic stress and changes in microbiome composition are associated with disease pathology. Stress is known to induce microbiome dysbiosis, defined here as a change in microbial composition associated with a pathological condition. This state of dysbiosis is known to feedback on depressive symptoms. While studies have demonstrated that targeted restoration of the microbiome can alleviate depressive-like symptoms in mice, translating these findings to human patients has proven challenging due to the complexity of the human microbiome. As such, there is an urgent need to identify factors upstream of microbial dysbiosis. Here we investigate the role of mucin 13 as an upstream mediator of microbiome composition changes in the context of stress. Using a model of chronic stress, we show that the glycocalyx protein, mucin 13, is selectively reduced after psychological stress exposure. We further demonstrate that the reduction of Muc13 is mediated by the Hnf4 transcription factor family. Finally, we determine that deleting Muc13 is sufficient to drive microbiome shifts and despair behaviors. These findings shed light on the mechanisms behind stress-induced microbial changes and reveal a novel regulator of mucin 13 expression.

Network medicine-based analysis of the hepatoprotective effects of Amomum villosum Lour. on alcoholic liver disease in rats

Alcoholic liver disease (ALD) is characterized by high morbidity and mortality, and mainly results from prolonged and excessive alcohol use. Amomum villosum Lour. (A. villosum), a well-known traditional Chinese medicine (TCM), has hepatoprotective properties. However, its ability to combat alcohol-induced liver injury has not been fully explored. The objective of this study was to investigate the hepatoprotective effects of A. villosum in a rat model of alcohol-induced liver disease, thereby establishing a scientific foundation for the potential preventive use of A. villosum in ALD. We established a Chinese liquor (Baijiu)-induced liver injury model in rats. Hematoxylin and eosin (HE) staining, in combination with biochemical tests, was used to evaluate the protective effects of A. villosum on the liver. The integration of network medicine analysis with experimental validation was used to explore the hepatoprotective effects and potential mechanisms of A. villosum in rats. Our findings showed that A. villosum ameliorated alcohol-induced changes in body weight, liver index, hepatic steatosis, inflammation, blood lipid metabolism, and liver function in rats. Network proximity analysis was employed to identify 18 potentially active ingredients of A. villosum for ALD treatment. These potentially active ingredients in the blood were further identified using mass spectrometry (MS). Our results showed that A. villosum plays a hepatoprotective role by modulating the protein levels of estrogen receptor 1 (ESR1), anti-nuclear receptor subfamily 3 group C member 1 (NR3C1), interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α). In conclusion, the results of the current study suggested that A. villosum potentially exerts hepatoprotective effects on ALD in rats, possibly through regulating the protein levels of ESR1, NR3C1, IL-6, and TNF-α.

Inflammatory liver diseases and susceptibility to sepsis

Patients with inflammatory liver diseases, particularly alcohol-associated liver disease and metabolic dysfunction-associated fatty liver disease (MAFLD), have higher incidence of infections and mortality rate due to sepsis. The current focus in the development of drugs for MAFLD is the resolution of non-alcoholic steatohepatitis and prevention of progression to cirrhosis. In patients with cirrhosis or alcoholic hepatitis, sepsis is a major cause of death. As the metabolic center and a key immune tissue, liver is the guardian, modifier, and target of sepsis. Septic patients with liver dysfunction have the highest mortality rate compared with other organ dysfunctions. In addition to maintaining metabolic homeostasis, the liver produces and secretes hepatokines and acute phase proteins (APPs) essential in tissue protection, immunomodulation, and coagulation. Inflammatory liver diseases cause profound metabolic disorder and impairment of energy metabolism, liver regeneration, and production/secretion of APPs and hepatokines. Herein, the author reviews the roles of (1) disorders in the metabolism of glucose, fatty acids, ketone bodies, and amino acids as well as the clearance of ammonia and lactate in the pathogenesis of inflammatory liver diseases and sepsis; (2) cytokines/chemokines in inflammatory liver diseases and sepsis; (3) APPs and hepatokines in the protection against tissue injury and infections; and (4) major nuclear receptors/signaling pathways underlying the metabolic disorders and tissue injuries as well as the major drug targets for inflammatory liver diseases and sepsis. Approaches that focus on the liver dysfunction and regeneration will not only treat inflammatory liver diseases but also prevent the development of severe infections and sepsis.

Dietary bile acids alleviate corticosterone-induced fatty liver and hepatic glucocorticoid receptor suppression in broiler chickens

The aim of this study was to investigate the alleviating effects and mechanisms of bile acids (BA) on corticosterone-induced fatty liver in broiler chickens. Male Arbor Acres chickens were randomly divided into 3 groups: control group (CON), stress model group (CORT), and BA-treated group (CORT-BA). The CORT-BA group received a diet with 250 mg/kg BA from 21 d of age. From days 36 to 43, both the CORT and CORT-BA groups received subcutaneous injections of corticosterone to simulate chronic stress. The results indicated that BA significantly mitigated the body weight loss, liver enlargement, and hepatic lipid deposition caused by corticosterone (P < 0.05). Liver RNA-seq analysis showed that BA alleviated corticosterone-induced fatty liver by inhibiting lipid metabolism pathways, including fatty acid biosynthesis, triglyceride biosynthesis, and fatty acid transport. Additionally, BA improved corticosterone-induced downregulation of glucocorticoid receptor (GR) expression (P < 0.05). Molecular docking and cellular thermal shift assays revealed that hyodeoxycholic acid (HDCA), a major component of compound BA, could bind to GR and enhance its stability. In conclusion, BA alleviated corticosterone-induced fatty liver in broilers by inhibiting lipid synthesis pathways and mitigating the suppression of hepatic GR expression.

Acute Deletion of the Glucocorticoid Receptor in Hepatocytes Disrupts Postprandial Lipid Metabolism in Male Mice

Hepatic lipid metabolism is highly dynamic, and disruption of several circadian transcriptional regulators results in hepatic steatosis. This includes genetic disruption of the glucocorticoid receptor (GR) as the liver develops. To address the functional role of GR in the adult liver, we used an acute hepatocyte-specific GR knockout model to study temporal hepatic lipid metabolism governed by GR at several preprandial and postprandial circadian timepoints. Lipidomics analysis revealed significant temporal lipid metabolism, where GR disruption results in impaired regulation of specific triglycerides, nonesterified fatty acids, and sphingolipids. This correlates with increased number and size of lipid droplets and mildly reduced mitochondrial respiration, most noticeably in the postprandial phase. Proteomics and transcriptomics analyses suggest that dysregulated lipid metabolism originates from pronounced induced expression of enzymes involved in fatty acid synthesis, β-oxidation, and sphingolipid metabolism. Integration of GR cistromic data suggests that induced gene expression is a result of regulatory actions secondary to direct GR effects on gene transcription.

Narrative Review: Glucocorticoids in Alcoholic Hepatitis—Benefits, Side Effects, and Mechanisms

Alcoholic hepatitis is a major health and economic burden worldwide. Glucocorticoids (GCs) are the only first-line drugs recommended to treat severe alcoholic hepatitis (sAH), with limited short-term efficacy and significant side effects. In this review, I summarize the major benefits and side effects of GC therapy in sAH and the potential underlying mechanisms. The review of the literature and data mining clearly indicate that the hepatic signaling of glucocorticoid receptor (GR) is markedly impaired in sAH patients. The impaired GR signaling causes hepatic down-regulation of genes essential for gluconeogenesis, lipid catabolism, cytoprotection, and anti-inflammation in sAH patients. The efficacy of GCs in sAH may be compromised by GC resistance and/or GC’s extrahepatic side effects, particularly the side effects of intestinal epithelial GR on gut permeability and inflammation in AH. Prednisolone, a major GC used for sAH, activates both the GR and mineralocorticoid receptor (MR). When GC non-responsiveness occurs in sAH patients, the activation of MR by prednisolone might increase the risk of alcohol abuse, liver fibrosis, and acute kidney injury. To improve the GC therapy of sAH, the effort should be focused on developing the biomarker(s) for GC responsiveness, liver-targeting GR agonists, and strategies to overcome GC non-responsiveness and prevent alcohol relapse in sAH patients.