Upregulation of hepatic CD36 via glucocorticoid receptor activation contributes to dexamethasone-induced liver lipid metabolism disorder in mice

Corticosterone induces fatty liver syndrome in chickens via glucocorticoid receptor and inhibition of mitochondrial supercomplex formation

Stress is a primary contributor to fatty liver syndrome (FLS) in chickens. Mitochondrial functionality is pivotal in FLS progression, with diminished supercomplex (SC) formation disrupting electron transport and escalating reactive oxygen species (ROS) production. However, the impact of stress on mitochondrial SC in chicken FLS remains elusive. This study used corticosterone (CORT) to model chronic stress and examined its consequences on mitochondrial performance and SC configuration in both in vivo and in vitro FLS models. Notably, the CORT-treated hepatocytes exhibited elevated triglyceride content (P < 0.05), accompanied by increased mitochondrial ROS (P < 0.01). Moreover, CORT-exposed broilers displayed reduced body weight (P < 0.05) alongside heightened liver-to-body weight ratio (P < 0.01), indicative of liver steatosis with increased triglyceride levels in both liver and plasma (P < 0.01). Mitochondrial alterations in reduced ATP content (P < 0.05). Gene expression analysis revealed enrichment in the mitochondrial respiratory chain pathway, with downregulated mRNA expression of complex I-associated SC assembly factors NADH: ubiquinone oxidoreductase complex assembly factor 5 (NDUFAF5), NADH: ubiquinone oxidoreductase complex assembly factor, and translocase of inner mitochondrial membrane domain containing 1 (P < 0.05). Meanwhile, the glucocorticoid receptor (GR) protein level and its specific binding to the NDUFAF5 gene promoter were reduced in the CORT group (P < 0.01 and P < 0.05, respectively), accompanied by a decrease in NDUFAF5 protein expression in liver, primary hepatocytes, and AML12 cells (P < 0.05). GR knockdown in AML12 cells reduced NDUFAF5 protein expression (P < 0.05). Thus, these findings imply that GR-mediated transcriptional regulation of complex I assembly factor NDUFAF5 may influence SC assembly, shedding light on stress-induced FLS mechanisms in broilers.NEW & NOTEWORTHY This study reveals the pivotal role of GR-mediated transcriptional regulation in stress-induced FLS in chickens. Chronic stress modeled with CORT disrupted mitochondrial SC assembly, impairing electron transport, elevated ROS production, and liver steatosis. Notably, the downregulation of complex I assembly factors (NDUFAF5, NDUFAF7, and TIMMDC1) and reduced GR binding to NDUFAF5 were key mechanisms. These findings provide new insights into stress-driven mitochondrial dysfunction in broiler FLS.

Reversed role of CD36 deficiency in high-fat diet or methionine/choline-deficient diet-induced hepatic steatosis and steatohepatitis

Introduction

Cluster of differentiation 36 (CD36) is highly expressed in the liver of patients with metabolic dysfunction-associated fatty liver disease (MAFLD) or metabolic dysfunction-associated steatohepatitis (MASH). However, the precise role of CD36 in MAFLD/MASH is controversial. In the current study, we aimed to uncover the role of CD36 in the early stage of MAFLD/MASH induced by high-fat diet (HFD) and methionine/choline-deficient (MCD) diet.

Methods

CD36-/- mice and littermate control mice were fed a normal food diet (NCD); HFD or MCD diet for 6 weeks.

Results

We determined that CD36 deficiency attenuated HFD-induced hepatic steatosis while exacerbating MCD diet-induced steatohepatitis. Mechanistically, CD36 deficiency reduced HFD-induced expression of fatty acid synthase (FASN), sterol regulatory element binding protein 1c (SREBP1c), and acetyl-CoA carboxylase alpha (ACC1), thereby inhibiting de novo fatty acid synthesis. The expression of superoxide dismutase and genes involving fatty acid oxidation was inhibited by MCD diet. CD36 deficiency reduced expression of genes involving fatty acid oxidation, while MCD diet had no effect on these genes expression in CD36-/- mice. Meanwhile, MCD diet-reduced superoxide dismutase expression was further inhibited by CD36 deficiency. Thus, MCD-induced liver ROS and inflammation were further enhanced by CD36 deficiency. By liver lipidomic analysis, we found that the levels of triglyceride (TG), diacylglycerols (DG), acylcarnitine (AcCA), ceramide (Cer) and LPC were increased, while phosphatidylcholine/phosphatidylethanolamine (PC/PE) were decreased in MCD diet-treated CD36-/- mice compared with MCD diet-treated wild type mice. Indeed, the expression of serine palmitoyltransferase 2 (SPTLC2), the key rate-limiting enzyme of ceramide synthesis, was higher in CD36-/- mice.

Discussion

CD36 deficiency improves HFD-induced MAFLD by inhibiting fatty acid synthesis, while accelerating MCD diet-induced MASH via promoting Cer, LPC, TG and DG accumulation to accelerate liver inflammation. The complex role of CD36 in MAFLD/MASH needs more investigation to discover the precise and effective strategy when targeting CD36.

Impacts of CD36 Variants on Plasma Lipid Levels and the Risk of Early-Onset Coronary Artery Disease: A Systematic Review and Meta-Analysis

Background: Recent studies have indicated that cluster of differentiation 36 (CD36) is closely linked to dyslipidemia and early-onset coronary artery disease (EOCAD). This study is aimed at investigating the impacts of CD36 gene variants on lipid profiles and EOCAD risk. Methods: PubMed, Cochrane Library, Central, CINAHL, and ClinicalTrials.gov were searched until June 15, 2024. Results: In total, 25 studies (11,494 individuals) were included for the analysis. The A allele carriers of the rs1761667 variant had higher high-density lipoprotein cholesterol (HDL-C) levels and higher EOCAD risk than noncarriers. In contrast, the G allele carriers of the rs1049673 and rs3211956 variants had lower low-density lipoprotein cholesterol (LDL-C) levels and lower EOCAD risk than noncarriers. Subgroup analysis indicated that the antiatherosclerotic impact and reduced EOCAD risk were primarily observed in Chinese with rs1049673 and rs3211956. Conclusions: The rs1761667, rs1049673, and rs3211956 variants of the CD36 gene have significant impacts on lipid levels and may serve as genetic markers for the risk of EOCAD primarily in Chinese. The impacts of CD36 variants on EOCAD risk are mediated, at least partly, by dyslipidemia. Genetic screening of CD36 gene variants may be helpful for early intervention or prevention of EOCAD in individuals with high risk factors.

Network Toxicology Analysis Reveals Molecular Mechanisms Associated with Noise Exposure to Multiple Diseases

Noise pollution is recognized as an environmental stressor that affects various biological processes beyond auditory functions, mainly through stress hormones release. This work explored the biological processes, diseases attributable to noise-regulated targets, and the main targets involved in each disease, employing a network toxicology approach. Through various databases and bioinformatics analysis, a total of 577 targets were identified as potential candidates implicated in diseases related to noise exposure, 10 from the GEO database and the rest from other databases. Noise pollution was found to regulate processes such as hormone response, cellular response to cytokines, and circulatory system functions, contributing to the development of the pathological manifestations related to the diseases like hypertension, ischemia, atherosclerosis, and cirrhosis. Hub targets for ischemia included IL-6, CASP3, AKT1, and TNF-α, while NOS3 was related to hypertension, and NOS3, TNF-α, AGT, and IL-1B to atherosclerosis. The targets were found to be linked to vascular regulation and inflammation in cardio- and cerebrovascular diseases. Molecular docking studies indicated stress hormones released by noise exposure regulates these diseases through signaling pathways, without implicating its direct binding to hub targets. The results indicate that individuals with vascular diseases are more vulnerable to the effects of prolonged noise exposure.

Dexamethasone synergizes with high-fat diet to increase lipid deposition in adipocytes

BACKGROUND/AIMS

Dexamethasone (DEX) is a widely used exogenous therapeutic glucocorticoid in clinical settings. Its long-term use leads to many side effects. However, its effect on metabolic disorders in individuals on a high-fat diet (HFD) remains poorly understood.

METHODS

In this study, HFD-fed mice were intraperitoneally injected with DEX 2.5 mg/kg/day for 30 days. Lipid metabolism, adipocyte proliferation, and inflammation were assayed using typical approaches.

RESULTS

DEX increased the epididymal fat index and epididymal adipocyte size in HFD-fed mice. The number of epididymal adipocytes with diameters > 70 μm accounted for 0.5% of the cells in the control group, 30% of the cells in the DEX group, 19% of the cells in the HFD group, and 38% of all the cells in the D+H group. Adipocyte proliferation in the D+H group was inhibited by DEX treatment. Adipocyte enlargement in the D+H group was associated with increased the lipid accumulation but not the adipocyte proliferation. In contrast, the liver triglyceride and total cholesterol levels and their metabolism were downregulated by the same treatment, indicating the therapeutic potential of DEX for nonalcoholic fatty liver disease.

CONCLUSION

DEX synergizes with HFD to promote lipid deposition in adipose tissues. A high risk of obesity development in patients receiving HFD and DEX treatment is suggested.

Prenatal stress induces sex- and tissue-specific alterations in insulin pathway of Wistar rats offspring

BACKGROUND AND AIMS

Prenatal stress may lead to tissue and sex-specific cardiometabolic disorders in the offspring through imbalances in the insulin signaling pathway. Therefore, we aimed to determine the sex-specific adaptations of prenatal stress on the insulin signaling pathway of cardiac and hepatic tissue of adult offspring Wistar rats.

METHODS

Wistar pregnant rats were divided into control and stress groups. Unpredictable stress protocol was performed from the 14th to the 21st day of pregnancy. After lactation, the dams were euthanized and blood was collected for corticosterone measurement and the offspring were separated into four groups according to sex and intervention (n=8/group). At 90 days old, the offspring were submitted to an oral glucose tolerance test (OGTT) and an insulin tolerance test (ITT). After euthanasia blood collection was used for biochemical analysis and the left ventricle and liver were used for protein expression and histological analysis.

RESULTS

Stress increased maternal corticosterone levels, and in the offspring, decreased glucose concentration in both OGTT and ITT, reduced insulin receptor (Irβ) and insulin receptor substrate-1 (IRS1) activation and reduced insulin receptor inhibition (PTP1B) in the liver of male offspring at 90 days old, without repercussions in cardiac tissue. Moreover, female offspring submitted to prenatal stress exhibited reduced fatty acid uptake, with lower hepatic CD36 expression, reduced high density lipoprotein (cHDL) and increased Castelli risk indexes I and II.

CONCLUSIONS

Unpredictable prenatal stress evoked reduced insulin sensitivity and liver-specific impairment in insulin signaling activation in male while increasing markers of cardiovascular risk in females.

Myricanol improves metabolic profiles in dexamethasone induced lipid and protein metabolism disorders in mice

Myricanol (MY) is one of the main active components from bark of Myrica Rubra. It is demonstrated that MY rescues dexamethasone (DEX)-induced muscle dysfunction via activating silent information regulator 1 (SIRT1) and increasing adenosine 5'-monophosphate-activated protein kinase (AMPK) phosphorylation. Since SIRT1 and AMPK are widely involved in the metabolism of nutrients, we speculated that MY may exert beneficial effects on DEX-induced metabolic disorders. This study for the first time applied widely targeted metabolomics to investigate the beneficial effects of MY on glucose, lipids, and protein metabolism in DEX-induced metabolic abnormality in mice. The results showed that MY significantly reversed DEX-induced soleus and gastrocnemius muscle weight loss, muscle fiber damage, and muscle strength loss. MY alleviated DEX-induced metabolic disorders by increasing SIRT1 and glucose transporter type 4 (GLUT4) expressions. Additionally, myricanol prevented muscle cell apoptosis and atrophy by inhibiting caspase 3 cleavages and muscle ring-finger protein-1 (MuRF1) expression. Metabolomics showed that MY treatment reversed the serum content of carnitine ph-C1, palmitoleic acid, PS (16:0_17:0), PC (14:0_20:5), PE (P-18:1_16:1), Cer (t18:2/38:1(2OH)), four amino acids and their metabolites, and 16 glycerolipids in DEX mice. Kyoto encyclopedia of genes and genomes (KEGG) and metabolic set enrichment analysis (MSEA) analysis revealed that MY mainly affected metabolic pathways, glycerolipid metabolism, lipolysis, fat digestion and absorption, lipid and atherosclerosis, and cholesterol metabolism pathways through regulation of metabolites involved in glutathione, butanoate, vitamin B6, glycine, serine and threonine, arachidonic acid, and riboflavin metabolism. Collectively, MY can be used as an attractive therapeutic agent for DEX-induced metabolic abnormalities.

Hedan tablet ameliorated non-alcoholic steatohepatitis by moderating NF-κB and lipid metabolism-related pathways via regulating hepatic metabolites

Non-alcoholic steatohepatitis (NASH) is a severe form of fatty liver disease. If not treated, it can lead to liver damage, cirrhosis and even liver cancer. However, advances in treatment have remained relatively slow, and there is thus an urgent need to develop appropriate treatments. Hedan tablet (HDP) is used to treat metabolic syndrome. However, scientific understanding of the therapeutic effect of HDP on NASH remains limited. We used HDP to treat a methionine/choline-deficient diet-induced model of NASH in rats to elucidate the therapeutic effects of HDP on liver injury. In addition, we used untargeted metabolomics to investigate the effects of HDP on metabolites in liver of NASH rats, and further validated its effects on inflammation and lipid metabolism following screening for potential target pathways. HDP had considerable therapeutic, anti-oxidant, and anti-inflammatory effects on NASH. HDP could also alter the hepatic metabolites changed by NASH. Moreover, HDP considerable moderated NF-κB and lipid metabolism-related pathways. The present study found that HDP had remarkable therapeutic effects in NASH rats. The therapeutic efficacy of HDP in NASH mainly associated with regulation of NF-κB and lipid metabolism-related pathways via arachidonic acid metabolism, glycine-serine-threonine metabolism, as well as steroid hormone biosynthesis.

Glucocorticoid receptor modulator CORT125385 alleviates diet-induced hepatosteatosis in male and female mice

Non-alcoholic fatty liver disease (NAFLD) is a common condition that can progress to the more severe conditions like non-alcoholic steatohepatitis (NASH) for which limited effective therapeutic options are available. In this study, we set out to evaluate the novel glucocorticoid receptor modulator CORT125385, an analogue of the previously studied miricorilant but without mineralocorticoid receptor binding activity. Male and female mice that received high-fat diet and fructose water were treated with either vehicle, CORT125385 or mifepristone. We found that CORT125385 significantly lowered hepatic triglyceride levels in male mice, and hepatic triglyceride and cholesterol levels in female mice. Mifepristone treatment had no effect in male mice, but significantly lowered hepatic triglyceride and cholesterol levels in female mice. In reporter assays in vitro, CORT125385 showed weak partial agonism on the progesterone receptor (PR) at high doses, as well as PR antagonism at a potency 1000-fold lower than mifepristone. In vivo, CORT125385 treatment did not influence PR-responsive gene expression in the oviduct, while mifepristone treatment strongly influenced these genes in the oviduct, thus excluding in vivo PR cross-reactivity of CORT125385 at a therapeutically active dose. We conclude that CORT125385 is a promising glucocorticoid receptor modulator that effectively reduces liver steatosis in male and female mice without affecting other steroid receptors at doses that lower hepatic lipid content.

Lipid droplet deposition in the regenerating liver: A promoter, inhibitor, or bystander?

Liver regeneration (LR) is a complex process involving intricate networks of cellular connections, cytokines, and growth factors. During the early stages of LR, hepatocytes accumulate lipids, primarily triacylglycerol, and cholesterol esters, in the lipid droplets. Although it is widely accepted that this phenomenon contributes to LR, the impact of lipid droplet deposition on LR remains a matter of debate. Some studies have suggested that lipid droplet deposition has no effect or may even be detrimental to LR. This review article focuses on transient regeneration-associated steatosis and its relationship with the liver regenerative response.

Alterations in hepatic transcriptome and cecum microbiota underlying potential ways to prevent early fatty liver in laying hens

Fatty liver syndrome (FLS) is a kind of nutritional metabolic disease in laying hens. Revealing FLS pathogenesis during the early period is what really makes sense for the prevention or nutritional regulation strategies. In the study, 9 healthy or naturally occurring early FLS birds were screened based on visual inspection, liver index and morphologic analysis. Liver and fresh cecal content samples were collected. Then transcriptomic and 16S rRNA technologies are applied to investigate hepatic transcriptome and cecum microbiota composition. Unpaired Student t test and some omics methods were used for statistical analysis. Results showed higher liver weight and index were found in FLS group; morphologic analysis indicated that there existed more lipid droplets in the liver of birds with FLS. Based on DESeq2 analysis, there were 229 up- and 487 down-regulated genes in the FLS group, among which most genes related to de novo fatty acid synthesis were up-regulated such as acetyl-CoA carboxylase, fatty acid synthase, stearoyl-CoA desaturase, and ELOVL fatty acid elongase 6 (ELOVL6). Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that pathways associated with lipid metabolism and liver damage were affected. 16S rRNA sequencing analysis of cecum microbiota showed that there was a significant difference between the Con and FLS groups. LEfSe analysis revealed that the relative abundance of Coprococcus, Odoribacter, Collinsella, Turicibacter, YRC22, Enterococcus, Shigella, and Bifidobacterium were down-regulated in the FLS group, whereas the abundance of Bacteroides, Mucispirillum, Butyricicoccus, Campylobacter, Akkermansia, and Clostridium were up-regulated. The KEGG enrichment from differential microbiota suggested that some metabolism-related functions were altered to some extent. Taken together, during the developmental of early fatty liver of laying hens, lipogenesis was enhanced, whereas abnormal metabolism occurs not only in lipid transportation but also in hydrolysis, which caused structural damage to the liver organ. Moreover, the dysbiosis of the cecum microbiota occurred. All of these serve as targets or provide theoretical references for the development of probiotics for fatty liver prevention in laying hens.