Lack of liver glycogen causes hepatic insulin resistance and steatosis in mice

Apigenin-6-C-glucoside ameliorates MASLD in rodent models via selective agonism of adiponectin receptor 2

Adiponectin plays key roles in energy metabolism and ameliorates inflammation, oxidative stress, and mitochondrial dysfunction via its primary receptors, adiponectin receptors -1 and 2 (AdipoR1 and AdipoR2). Systemic depletion of adiponectin causes various metabolic disorders, including MASLD; however adiponectin supplementation is not yet achievable owing to its large size and oligomerization-associated complexities. Small-molecule AdipoR agonists, thus, may provide viable therapeutic options against metabolic disorders. Using a novel luciferase reporter-based assay here, we have identified Apigenin-6-C-glucoside (ACG), but not apigenin, as a specific agonist for the liver-rich AdipoR isoform, AdipoR2 (EC50: 384 pM) with >10000X preference over AdipoR1. Immunoblot analysis in HEK-293 overexpressing AdipoR2 or HepG2 and PLC/PRF/5 liver cell lines revealed rapid AMPK, p38 activation and induction of typical AdipoR targets PGC-1α and PPARα by ACG at a pharmacologically relevant concentration of 100 nM (reported cMax in mouse; 297 nM). ACG-mediated AdipoR2 activation culminated in a favorable modulation of key metabolic events, including decreased inflammation, oxidative stress, mitochondrial dysfunction, de novo lipogenesis, and increased fatty acid β-oxidation as determined by immunoblotting, QRT-PCR and extracellular flux analysis. AdipoR2 depletion or AMPK/p38 inhibition dampened these effects. The in vitro results were recapitulated in two different murine models of MASLD, where ACG at 10 mg/kg body weight robustly reduced hepatic steatosis, fibrosis, proinflammatory macrophage numbers, and increased hepatic glycogen content. Together, using in vitro experiments and rodent models, we demonstrate a proof-of-concept for AdipoR2 as a therapeutic target for MASLD and provide novel chemicobiological insights for the generation of translation-worthy pharmacological agents.

Calebin A attenuated inflammation in RAW264.7 macrophages and adipose tissue to improve hepatic glucose metabolism and hyperglycemia in high-fat diet-fed obese mice

The increased incidence of obesity, which become a global health problem, requires more functional food products with minor side and excellent effects. Calebin A (CbA) is a non-curcuminoid compound, which is reported to be an effective treatment for lipid metabolism and thermogenesis. However, its ability and mechanism of action in improving obesity-associated hyperglycemia remain unclear. This study was designed to explore the effect and mechanism of CbA in hyperglycemia via improvement of inflammation and glucose metabolism in the adipose tissue and liver in high-fat diet (HFD)-fed mice. After 10 weeks fed HFD, obese mice supplemented with CbA (25 and 100 mg/kg) for another 10 weeks showed a remarkable reducing adiposity and blood glucose. CbA modulated M1/M2 macrophage polarization, ameliorated inflammatory cytokines, and restored adiponectin as well as Glut 4 expression in the adipose tissue. In the in vitro study, CbA attenuated pro-inflammatory markers while upregulated anti-inflammatory IL-10 in LPS + IFNγ-generated M1 phenotype macrophages. In the liver, CbA attenuated steatosis, inflammatory infiltration, and protein levels of inflammatory TNF-α and IL-6. Moreover, CbA markedly upregulated Adiponectin receptor 1, AMPK, and insulin downstream Akt signaling to improve glycogen content and increase Glut2 protein. These findings indicated that CbA may be a novel therapeutic approach to treat obesity and hyperglycemia phenotype targeting on adipose inflammation and hepatic insulin signaling.

miR-141/200c contributes to ethanol-mediated hepatic glycogen metabolism

OBJECTIVE

Hepatic glucose metabolism is profoundly perturbed by excessive alcohol intake. miR-141/200c expression is significantly induced by chronic ethanol feeding. This study aimed at identifying the role of miR-141/200c in glucose homeostasis during chronic ethanol exposure.

METHODS

WT and miR-141/200c KO mice were fed a control or an ethanol diet for 30 days, followed by a single binge of maltose dextrin or ethanol, respectively. Untargeted metabolomics analysis of hepatic primary metabolites was performed along with analyses for liver histology, gene expression, intracellular signaling pathways, and physiological relevance. Primary hepatocytes were used for mechanistic studies.

RESULTS

miR-141/200c deficiency rewires hepatic glucose metabolism during chronic ethanol feeding, increasing the abundance of glucose intermediates including G6P, an allosteric activator for GS. miR-141/200c deficiency replenished glycogen depletion during chronic ethanol feeding accompanied by reduced GS phosphorylation in parallel with increased expression of PP1 glycogen targeting subunits. Moreover, miR-141/200c deficiency prevented ethanol-mediated increases in AMPK and CaMKK2 activity. Ethanol treatment reduced glycogen content in WT-hepatocytes, which was reversed by dorsomorphin, a selective AMPK inhibitor, while KO-hepatocytes displayed higher glycogen content than WT-hepatocytes in response to ethanol treatment. Furthermore, treatment of hepatocytes with A23187, a calcium ionophore activating CaMKK2, lowered glycogen content in WT-hepatocytes. Notably, the suppressive effect of A23187 on glycogen deposition was reversed by dorsomorphin, demonstrating that the glycogen depletion by A23187 is mediated by AMPK. KO-hepatocytes exhibited higher glycogen content than WT-hepatocytes in response to A23187. Finally, miR-141/200c deficiency led to improved glucose tolerance and insulin sensitivity during chronic ethanol feeding.

CONCLUSIONS

miR-141/200c deficiency replenishes ethanol-mediated hepatic glycogen depletion through the regulation of GS activity and calcium signaling coupled with the AMPK pathway, improving glucose homeostasis and insulin sensitivity. These results underscore miR-141/200c as a potential therapeutic target for the management of alcohol intoxication.

From NAFLD to NASH: Understanding the spectrum of non-alcoholic liver diseases and their consequences

Non-alcoholic fatty liver disease (NAFLD) has become one of the most frequent chronic liver diseases worldwide in recent decades. Metabolic diseases like excessive blood glucose, central obesity, dyslipidemia, hypertension, and liver function abnormalities cause NAFLD. NAFLD significantly increases the likelihood of liver cancer, heart disease, and mortality, making it a leading cause of liver transplants. Non-alcoholic steatohepatitis (NASH) is a more advanced form of the disease that causes scarring and inflammation of the liver over time and can ultimately result in cirrhosis and hepatocellular carcinoma. In this review, we briefly discuss NAFLD's pathogenic mechanisms, their progression into NASH and afterward to NASH-related cirrhosis. It also covers disease epidemiology, metabolic mechanisms, glucose and lipid metabolism in the liver, macrophage dysfunction, bile acid toxicity, and liver stellate cell stimulation. Additionally, we consider the contribution of intestinal microbiota, genetics, epigenetics, and ecological factors to fibrosis progression and hepatocellular carcinoma risk in NAFLD and NASH patients.

Synthesis and biological evaluation of the novel chrysin prodrug for non-alcoholic fatty liver disease treatment

Background: Chrysin (5,7-dihydroxyflavone) is a natural flavonoid that has been reported as a potential treatment for non-alcoholic fatty liver disease (NAFLD). However, extensive phase II metabolism and poor aqueous solubility led to a decrease in the chrysin concentration in the blood after oral administration, limiting its pharmacological development in vivo. Methods: In the present study, we synthesized a novel chrysin derivative prodrug (C-1) to address this issue. We introduced a hydrophilic prodrug group at the 7-position hydroxyl group, which is prone to phase II metabolism, to improve water solubility and mask the metabolic site. Further, we evaluated the ameliorative effects of C-1 on NAFLD in vitro and in vivo by NAFLD model cells and db/db mice. Results: In vitro studies indicated that C-1 has the ability to ameliorate lipid accumulation, cellular damage, and oxidative stress in NAFLD model cells. In vivo experiments showed that oral administration of C-1 at a high dose (69.3 mg/kg) effectively ameliorated hyperlipidemia and liver injury and reduced body weight and liver weight in db/db mice, in addition to alleviating insulin resistance. Proteomic analysis showed that C-1 altered the protein expression profile in the liver and particularly improved the expression of proteins associated with catabolism and metabolism. Furthermore, in our preliminary pharmacokinetic study, C-1 showed favorable pharmacokinetic properties and significantly improved the oral bioavailability of chrysin. Conclusion: Our data demonstrated that C-1 may be a promising agent for NAFLD therapy.

Obesogenic Diet in Mice Leads to Inflammation and Oxidative Stress in the Mother in Association with Sex-Specific Changes in Fetal Development, Inflammatory Markers and Placental Transcriptome

BACKGROUND

Obesity during pregnancy is related to adverse maternal and neonatal outcomes. Factors involved in these outcomes may include increased maternal insulin resistance, inflammation, oxidative stress, and nutrient mishandling. The placenta is the primary determinant of fetal outcomes, and its function can be impacted by maternal obesity. The aim of this study on mice was to determine the effect of obesity on maternal lipid handling, inflammatory and redox state, and placental oxidative stress, inflammatory signaling, and gene expression relative to female and male fetal growth.

METHODS

Female mice were fed control or obesogenic high-fat/high-sugar diet (HFHS) from 9 weeks prior to, and during, pregnancy. On day 18.5 of pregnancy, maternal plasma, and liver, placenta, and fetal serum were collected to examine the immune and redox states. The placental labyrinth zone (Lz) was dissected for RNA-sequencing analysis of gene expression changes.

RESULTS

the HFHS diet induced, in the dams, hepatic steatosis, oxidative stress (reduced catalase, elevated protein oxidation) and the activation of pro-inflammatory pathways (p38-MAPK), along with imbalanced circulating cytokine concentrations (increased IL-6 and decreased IL-5 and IL-17A). HFHS fetuses were asymmetrically growth-restricted, showing sex-specific changes in circulating cytokines (GM-CSF, TNF-α, IL-6 and IFN-γ). The morphology of the placenta Lz was modified by an HFHS diet, in association with sex-specific alterations in the expression of genes and proteins implicated in oxidative stress, inflammation, and stress signaling. Placental gene expression changes were comparable to that seen in models of intrauterine inflammation and were related to a transcriptional network involving transcription factors, LYL1 and PLAG1.

CONCLUSION

This study shows that fetal growth restriction with maternal obesity is related to elevated oxidative stress, inflammatory pathways, and sex-specific placental changes. Our data are important, given the marked consequences and the rising rates of obesity worldwide.

High glucose exposure of preimplantation embryos causes glucose intolerance and insulin resistance in F1 and F2 male offspring

BACKGROUND

Although studies suggest that maternal high glucose (HG) increases offspring susceptibility to type 2 diabetes mellitus (T2DM), the underlying mechanisms are largely unclear. We studied whether glucose levels in oviducts are elevated when pregestational diabetic females get pregnant and whether the oviductal HG (OVHG) would act directly on embryos to increase offspring's T2DM susceptibility.

METHODS

We established an in vivo model of OVHG by injecting female mice with streptozotocin (STZ) during the preimplantation period and an in vitro model of embryo culture with HG (ECHG) by culturing preimplantation embryos with HG, before examining glucose tolerance and insulin resistance (IR) in F1 and F2 offspring.

FINDINGS

Injection of female mice with STZ induced a lasting significant glucose elevation in blood and oviduct fluid during the preimplantation period. The glucose tolerance test showed that both the STZ-induced OVHG and the ECHG caused glucose intolerance in F1 male and F1-sired F2 male offspring but had no effect on female offspring. Insulin tolerance test and the analysis for IR-related gene expression and glycogen contents in liver and muscle revealed significant IR in these male offspring.

INTERPRETATION

This study provided evidence that HG can act directly on preimplantation embryos to increase offspring's T2DM susceptibility suggesting that the preimplantation period is a critical stage for transmission of mother's diabetes to offspring. FUND: This study was supported by grants from the China National Natural Science Foundation (Nos. 31772599, 32072738, 31702114, and 31902160), and the Natural Science Foundation of Shandong Province (Nos. ZR2022MC036, ZR2017BC025 and ZR2020QC102).

Molecular mechanisms of metabolic disease-associated hepatic inflammation in non-alcoholic fatty liver disease and non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the leading chronic liver disease worldwide, with a progressive form of non-alcoholic steatohepatitis (NASH). It may progress to advanced liver diseases, including liver fibrosis, cirrhosis, and hepatocellular carcinoma. NAFLD/NASH is a comorbidity of many metabolic disorders such as obesity, insulin resistance, type 2 diabetes, cardiovascular disease, and chronic kidney disease. These metabolic diseases are often accompanied by systemic or extrahepatic inflammation, which plays an important role in the pathogenesis and treatment of NAFLD or NASH. Metabolites, such as short-chain fatty acids, impact the function, inflammation, and death of hepatocytes, the primary parenchymal cells in the liver tissue. Cholangiocytes, the epithelial cells that line the bile ducts, can differentiate into proliferative hepatocytes in chronic liver injury. In addition, hepatic non-parenchymal cells, including liver sinusoidal endothelial cells, hepatic stellate cells, and innate and adaptive immune cells, are involved in liver inflammation. Proteins such as fibroblast growth factors, acetyl-coenzyme A carboxylases, and nuclear factor erythroid 2-related factor 2 are involved in liver metabolism and inflammation, which are potential targets for NASH treatment. This review focuses on the effects of metabolic disease-induced extrahepatic inflammation, liver inflammation, and the cellular and molecular mechanisms of liver metabolism on the development and progression of NAFLD and NASH, as well as the associated treatments.

Estimation of fatty liver disease clinical role on glucose metabolic remodelling phenotypes and T2DM onset

INTRODUCTION

Metabolic syndrome (MetS), prediabetes (PreDM) and Fatty Liver Disease (FLD) share pathophysiological pathways concerning type 2 diabetes mellitus (T2DM) onset. The non-invasive assessment of fatty liver combined with PreDM and MetS features screening might provide further accuracy in predicting hyperglycemic status in the clinical setting with the putative description of singular phenotypes. The objective of the study is to evaluate and describe the links of a widely available FLD surrogate -the non-invasive serological biomarker Hepatic Steatosis Index (HSI)- with previously described T2DM risk predictors, such as preDM and MetS in forecasting T2DM onset.

PATIENTS AND METHODS

A retrospective ancillary cohort study was performed on 2799 patients recruited in the Vascular-Metabolic CUN cohort. The main outcome was the incidence of T2DM according to ADA criteria. MetS and PreDM were defined according to ATP III and ADA criteria, respectively. Hepatic steatosis index (HSI) with standardized thresholds was used to discriminate patients with FLD, which was referred as estimated FLD (eFLD).

RESULTS

MetS and PreDM were more common in patients with eFLD as compared to those with an HSI < 36 points (35% vs 8% and 34% vs. 18%, respectively). Interestingly, eFLD showed clinical effect modification with MetS and PreDM in the prediction of T2DM [eFLD-MetS interaction HR = 4.48 (3.37-5.97) and eFLD-PreDM interaction HR = 6.34 (4.67-8.62)]. These findings supported the description of 5 different liver status-linked phenotypes with increasing risk of T2DM: Control group (1,5% of T2DM incidence), eFLD patients (4,4% of T2DM incidence), eFLD and MetS patients (10,6% of T2DM incidence), PreDM patients (11,1% of T2DM incidence) and eFLD and PreDM patients (28,2% of T2DM incidence). These phenotypes provided independent capacity of prediction of T2DM incidence after adjustment for age, sex, tobacco and alcohol consumption, obesity and number of SMet features with a c-Harrell=0.84.

CONCLUSION

Estimated Fatty Liver Disease using HSI criteria (eFLD) interplay with MetS features and PreDM might help to discriminate patient risk of T2DM in the clinical setting through the description of independent metabolic risk phenotypes. [Correction added on 15 June 2023, after first online publication: The abstract section was updated in this current version.].

Benefits of Combining Sonchus brachyotus DC. Extracts and Synbiotics in Alleviating Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease, commonly abbreviated to NAFLD, is a pervasive ailment within the digestive system, exhibiting a rising prevalence, and impacting individuals at increasingly younger ages. Those afflicted by NAFLD face a heightened vulnerability to the onset of profound liver fibrosis, cardiovascular complications, and malignancies. Currently, NAFLD poses a significant threat to human health, and there is no approved therapeutic treatment for it. Recent studies have shown that synbiotics, which regulate intestinal microecology, can positively impact glucolipid metabolism, and improve NAFLD-related indicators. Sonchus brachyotus DC., a Chinese herb, exhibits hepatoprotective and potent antioxidant properties, suggesting its potential therapeutic use in NAFLD. Our preclinical animal model investigation suggests that the synergy between Sonchus brachyotus DC. extracts and synbiotics is significantly more effective in preventing and treating NAFLD, compared to the isolated use of either component. As a result, this combination holds the potential to introduce a fresh and encouraging therapeutic approach to addressing NAFLD.

Integration of Transcriptomics and Lipidomics Profiling to Reveal the Therapeutic Mechanism Underlying Ramulus mori (Sangzhi) Alkaloids for the Treatment of Liver Lipid Metabolic Disturbance in High-Fat-Diet/Streptozotocin-Induced Diabetic Mice

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder, with a global prevalence of 25%. Currently, there remains no approved therapy. Ramulus mori (Sangzhi) alkaloids (SZ-As), a novel natural medicine, have achieved comprehensive benefits in the treatment of type 2 diabetes; however, few studies have focused on its role in ameliorating hepatic lipid metabolic disturbance. Herein, the therapeutic effect and mechanism of SZ-As on a high-fat diet (HFD) combined with streptozotocin (STZ)-induced NAFLD mice were investigated via incorporating transcriptomics and lipidomics. SZ-As reduced body weight and hepatic lipid levels, restored pathological alternation and converted the blood biochemistry perturbations. SZ-A treatment also remarkedly inhibited lipogenesis and enhanced lipolysis, fatty acid oxidation and thermogenesis. Transcriptomics analysis confirmed that SZ-As mainly altered fatty acid oxidative metabolism and the TNF signaling pathway. SZ-As were further demonstrated to downregulate inflammatory factors and effectively ameliorate hepatic inflammation. Lipidomics analysis also suggested that SZ-As affected differential lipids including triglyceride (TG) and phosphatidylcholine (PC) expression, and the main metabolic pathways included glycerophospholipid, sphingomyelins and choline metabolism. Collectively, combined with transcriptomics and metabolomics data, it is suggested that SZ-As exert their therapeutic effect on NAFLD possibly through regulating lipid metabolism pathways (glycerophospholipid metabolism and choline metabolism) and increasing levels of PC and lysophosphatidylcholine (LPC) metabolites. This study provides the basis for more widespread clinical applications of SZ-As.

Dendropanoxide Alleviates Thioacetamide-induced Hepatic Fibrosis via Inhibition of ROS Production and Inflammation in BALB/C Mice

Hepatic fibrosis results from overproduction and excessive accumulation of extracellular matrix (ECM) proteins in hepatocytes. Although the beneficial effects of dendropanoxide (DPx) isolated from Dendropanax morbifera have been studied, its role as an anti-fibrotic agent remains elucidated. We investigated the protective effect of DPx in BALB/_C mice that received thioacetamide (TAA) intraperitoneally for 6 weeks. Later DPx (20 mg/kg/day) or silymarin (50 mg/kg/day) was administered daily for 6 weeks, followed by biochemical and histological analyses of each group. Hematoxylin and eosin staining of the livers showed TAA-induced hepatic fibrosis, which was significantly reduced in the DPx group. DPx treatment significantly decreased TAA-induced hyperlipidemia as evidenced by the decreased AST, ALT, ALP, γ-GTP and serum TG concentrations and reduced the activities of catalase (CAT) and superoxide dismutase (SOD) activity. ELISA revealed reduced levels of total glutathione (GSH), malondialdehyde (MDA) and Inflammatory factors (IL-6, IL-1β, and TNF-α). Immunostaining showed reduced in collagen-1, α-SMA, and TGF-β1 expression and western blotting showed reduced levels of the apoptotic proteins, TGF-β1, p-Smad2/3, and Smad4. RT-qPCR and Western blotting revealed modifications in SIRT1, SIRT3 and SIRT4. Thus, DPx exerted a protective effect against TAA-induced hepatic fibrosis in the male BALB/_C mouse model by inhibiting oxidative stress, inflammation, and apoptosis via TGF-β1/Smads signaling.

Restoration of lysosomal acidification rescues autophagy and metabolic dysfunction in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the world. High levels of free fatty acids in the liver impair hepatic lysosomal acidification and reduce autophagic flux. We investigate whether restoration of lysosomal function in NAFLD recovers autophagic flux, mitochondrial function, and insulin sensitivity. Here, we report the synthesis of novel biodegradable acid-activated acidifying nanoparticles (acNPs) as a lysosome targeting treatment to restore lysosomal acidity and autophagy. The acNPs, composed of fluorinated polyesters, remain inactive at plasma pH, and only become activated in lysosomes after endocytosis. Specifically, they degrade at pH of ~6 characteristic of dysfunctional lysosomes, to further acidify and enhance the function of lysosomes. In established in vivo high fat diet mouse models of NAFLD, re-acidification of lysosomes via acNP treatment restores autophagy and mitochondria function to lean, healthy levels. This restoration, concurrent with reversal of fasting hyperglycemia and hepatic steatosis, indicates the potential use of acNPs as a first-in-kind therapeutic for NAFLD.

Gut microbiome-mediated glucose and lipid metabolism mechanism of star apple leaf polyphenol-enriched fraction on metabolic syndrome in diabetic mice

BACKGROUND

Diabetes is a kind of metabolic syndrome (MetS) that seriously threatens human health globally. The leaf of star apple (Chrysophyllum cainito L.) is an incompletely explored folk medicine on diabetes. And, the effects and mechanisms on diabetes complicated glycolipid metabolism disorders are unknown till now.

PURPOSE

This study aimed to investigate the constituents of star apple leaf polyphenol enriched-fraction (SAP), and elucidate their treatment effects and mechanism on diabetes and accompanied other MetS.

METHODS

The components of SAP were tentatively identified by HPLC-Q-TOF-MS/MS. The antioxidant activity was determined by the scavenging of free radicals and hypoglycemic activities by inhibition of α-glucosidase in vitro. HepG2 cells were used for evaluating the alleviation effects of SAP on lipid accumulation. Streptozotocin and high-fat diet induced diabetic mice were grouped to evaluate the effects of different dosages of SAP. 16S rRNA was conducted to analysis gut microbiome-mediated glucose and lipid metabolism mechanism.

RESULTS

It showed that myricitrin was one of the main active constituents of SAP. SAP not only showed low IC50 on -glucosidase (24.427± 0.626 μg/mL), OH·(3.680± 0.054 μg/mL) and ABTS· (9.155±0.234 μg/mL), but significantly induced the lipid accumulation in HepG2 cells (p < 0.05). SAP at 200 mg/kg·day significantly decreased the blood glucose, insulin and oral glucose tolerance test value (p < 0.05). The insulin resistance indexes and oxidative stress were alleviated after administration. SAP not only attenuated hepatic lipid deposition, but also reversed the hepatic glycogen storage. 16S rRNA sequencing results revealed that the interaction between SAP and gut microbiota led to the positive regulation of beneficial bacteria including Akkermansia, Unspecified S24_7, Alistipes and Unspecified_Ruminococcaceae, which might be one of the mechanisms of SAP on MetS.

CONCLUSION

For the first time, this study explored the regulation effect of star apple leaf polyphenols on the hepatic glycolipid metabolism and studied the underlying mechanism from the view of gut microbiota. These findings indicated that SAP possesses great potential to serve as a complementary medicine for diabetes and associated MetS. It provided scientific evidence for folk complementary medicine on the treatment of diabetes-complicated multiple metabolic disorders.

The effect of G0S2 on insulin sensitivity: A proteomic analysis in a G0S2-overexpressed high-fat diet mouse model

BACKGROUND

Previous research has shown a tight relationship between the G0/G1 switch gene 2 (G0S2) and metabolic diseases such as non-alcoholic fatty liver disease (NAFLD) and obesity and diabetes, and insulin resistance has been shown as the major risk factor for both NAFLD and T2DM. However, the mechanisms underlying the relationship between G0S2 and insulin resistance remain incompletely understood. Our study aimed to confirm the effect of G0S2 on insulin resistance, and determine whether the insulin resistance in mice fed a high-fat diet (HFD) results from G0S2 elevation.

METHODS

In this study, we extracted livers from mice that consumed HFD and received tail vein injections of AD-G0S2/Ad-LacZ, and performed a proteomics analysis.

RESULTS

Proteomic analysis revealed that there was a total of 125 differentially expressed proteins (DEPs) (56 increased and 69 decreased proteins) among the identified 3583 proteins. Functional enrichment analysis revealed that four insulin signaling pathway-associated proteins were significantly upregulated and five insulin signaling pathway -associated proteins were significantly downregulated.

CONCLUSION

These findings show that the DEPs, which were associated with insulin resistance, are generally consistent with enhanced insulin resistance in G0S2 overexpression mice. Collectively, this study demonstrates that G0S2 may be a potential target gene for the treatment of obesity, NAFLD, and diabetes.

High-refined carbohydrate diet alters different metabolic functions in female rats

A diet containing refined carbohydrate (HCD) caused obesity and white adipose tissue (WAT) abnormalities, but it is unclear if HCD is linked with other metabolic dysfunctions in female models. Thus, we assessed whether HCD results in WAT, pancreas, liver, skeletal muscle (SM) and thyroid (TH) abnormalities in female rats. Female rats were fed with HCD for 15 days and metabolic morphophysiology, inflammation, oxidative stress (OS), and fibrosis markers were assessed. HCD rats presented large adipocytes, hyperleptinemia, and WAT OS. HCD caused irregular glucose metabolism, low insulin levels, and large pancreatic isle. Granulomas, reduced glycogen, and OS were observed in HCD livers. HCD caused hypertrophy and increased in glycogen in SM. HCD caused irregular TH morphophysiology, reduced colloid area and high T3 levels. In all selected tissues, inflammation and fibrosis were observed in HCD rats. Collectively, these data suggest that the HCD impairs metabolic function linked with irregularities in WAT, pancreas, liver, SM and TH in female rats.

Aqueous extract of Artemisia capillaris improves non-alcoholic fatty liver and obesity in mice induced by high-fat diet

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases and is a nutritional metabolic disease. Artemisia capillaris (AC) is the above-ground dried part of Artemisia capillaris Thunb. or Artemisia scoparia Waldst. et Kit., a natural medicinal plant with pharmacological effects of heat-clearing and biliary-promoting. In order to evaluate the therapeutic effect of Artemisia capillaris on NAFLD and obesity, experiments were conducted using aqueous extracts of Artemisia capillaris (WAC) to intervene in NAFLD models in vivo and in vitro. In vivo experiments were performed using HFD-fed (high fat diet) C57BL/6 mice to induce NAFLD model, and in vitro experiments were performed using oleic acid to induce HepG2 cells to construct NAFLD cell model. H.E. staining and oil red O staining of liver tissue were used to observe hepatocytes. Blood biochemistry analyzer was used to detect serum lipid levels in mice. The drug targets and mechanism of action of AC to improve NAFLD were investigated by western blotting, qRT-PCR and immunofluorescence. The results showed that C57BL/6 mice fed HFD continuously for 16 weeks met the criteria for NAFLD in terms of lipid index and hepatocyte fat accumulation. WAC was able to reverse the elevation of serum lipid levels induced by high-fat diet in mice. WAC promoted the phosphorylation levels of PI3K/AKT and AMPK in liver and HepG2 cells of NAFLD mice, inhibited SREBP-1c expression, reduced TG and lipogenesis, and decreased lipid accumulation. In summary, WAC extract activates PI3K/AKT pathway, reduces SREBP-1c protein expression by promoting AMPK phosphorylation, and decreases fatty acid synthesis and TG content in hepatocytes. AC can be used as a potential health herb to improve NAFLD and obesity.

Integration of Lipidomics and Transcriptomics Reveals the Efficacy and Mechanism of Qige Decoction on NAFLD

The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing as obesity and diabetes become more common. There are no drugs approved for NAFLD yet. Qige decoction (QGD), a traditional Chinese medicine (TCM) formula, is used for NAFLD and hyperlipidemia treatment in TCM and has shown hypolipidemic and hepatoprotective effects. This study tried to interpret the pharmacology and molecular mechanisms of QGD in NAFLD rats. Firstly, the therapeutic effects of QGD on high-fat diet (HFD)-induced NAFLD rats were evaluated. Then, integration of lipidomics and transcriptomics was conducted to explore the possible pathways and targets of QGD against NAFLD. QGD at low dosage (QGL) administration reduced serum total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) ( $P<0.05$ ). Liver histopathology indicated that QGL could alleviate hepatic steatosis. The main differential lipids (DELs) affected by QGD were glycerolipids. KEGG enrichment analysis suggested that the main pathways by which QGD improved NAFLD may be cholesterol metabolism, glycerolipid metabolism, and insulin resistance. Transcriptome sequencing identified 179 upregulated and 194 downregulated mRNAs after QGD treatment. An interaction network based on DELs and differential genes (DEGs) suggested that QGD inhibited hepatic steatosis mainly by reducing hepatic insulin resistance and triglyceride biosynthesis via the PPP1R3C/SIK1/CRTC2 and PPP1R3C/SIK1/SREBP1 signal axis, respectively. These findings indicated that QGD could protect against NAFLD induced by HFD. The improvement of hepatic insulin resistance and the reduction of triglyceride biosynthesis might be the potential mechanisms.

Chronotherapy with a glucokinase activator profoundly improves metabolism in obese Zucker rats

Circadian rhythms play a critical role in regulating metabolism, including daily cycles of feeding/fasting. Glucokinase (GCK) is central for whole-body glucose homeostasis and oscillates according to a circadian clock. GCK activators (GKAs) effectively reduce hyperglycemia, but their use is also associated with hypoglycemia, hyperlipidemia, and hepatic steatosis. Given the circadian rhythmicity and natural postprandial activation of GCK, we hypothesized that GKA treatment would benefit from being timed specifically during feeding periods. Acute treatment of obese Zucker rats with the GKA AZD1656 robustly increased flux into all major metabolic pathways of glucose disposal, enhancing glucose elimination. Four weeks of continuous AZD1656 treatment of obese Zucker rats improved glycemic control; however, hepatic steatosis and inflammation manifested. In contrast, timing AZD1656 to feeding periods robustly reduced hepatic steatosis and inflammation in addition to improving glycemia, whereas treatment timed to fasting periods caused overall detrimental metabolic effects. Mechanistically, timing AZD1656 to feeding periods diverted newly synthesized lipid toward direct VLDL secretion rather than intrahepatic storage. In line with increased hepatic insulin signaling, timing AZD1656 to feeding resulted in robust activation of AKT, mTOR, and SREBP-1C after glucose loading, pathways known to regulate VLDL secretion and hepatic de novo lipogenesis. In conclusion, intermittent AZD1656 treatment timed to feeding periods promotes glucose disposal when needed the most, restores metabolic flexibility and hepatic insulin sensitivity, and thereby avoids hepatic steatosis. Thus, chronotherapeutic approaches may benefit the development of GKAs and other drugs acting on metabolic targets.

Function of gaseous hydrogen sulfide in liver fibrosis

Over the past few years, hydrogen sulfide (H₂S) has been shown to exert several biological functions in mammalian. The endogenous production of H₂S is mainly mediated by cystathione β-synthase, cystathione γ-lyase and 3-mercaptopyruvate sulfur transferase. These enzymes are broadly expressed in liver tissue and regulates liver function by working on a variety of molecular targets. As an important regulator of liver function, H₂S is critically involved in the pathogenesis of various liver diseases, such as non-alcoholic steatohepatitis and liver cancer. Targeting H₂S-generating enzymes may be a therapeutic strategy for controlling liver diseases. This review described the function of H₂S in liver disease and summarized recent characterized role of H₂S in several cellular process of the liver.

Comparison of six surrogate insulin resistance indexes for predicting the risk of incident stroke: The Rural Chinese Cohort Study

BACKGROUND AND PURPOSE

Some cheap and easily used operated indexes of insulin resistance (IR) were currently available. We aimed to evaluate the association of six surrogate indexes of IR with incident stroke and to compare their predictive capacity.

METHODS

We analysed data from 14,595 eligible study participants from the Rural Chinese Cohort Study. Modified Poisson regression models were used to estimate relative risks (RRs) and 95% confidence intervals (95% CIs) of incident stroke associated with the visceral adiposity index (VAI), the Chinese visceral adiposity index (CVAI), lipid accumulation product (LAP), triglyceride-glucose (TyG), TyG-body mass index, and TyG-waist circumference. The receiver operator characteristic curve was used to compare the ability of the abovementioned IR indexes to predict stroke.

RESULTS

During a median follow-up of 6 years, 786 newly diagnosed stroke cases were identified. The levels of six surrogate indexes of IR were all significantly higher in the stroke population than in the non-stroke population (p < 0.001). Compared with quartile 1, the multivariable adjusted RRs (95% CIs) of incident stroke for quartile 4 were 2.01 (1.47-2.76), 1.62 (1.28, 2.04), 1.64 (1.28-2.09), and 1.92 (1.50-2.45) for CVAI, VAI, LAP, and TyG, respectively. Significant dose-response associations were also found between surrogate IR indexes and risk of stroke. The area under the curves|areas under the curves for CVAI (0.674) was significantly greater than for other indexes (TyG-WC:0.622, TyG:0.614, LAP:0.606, TyG-BMI:0.598, and VAI:0.577) (p < 0.001).

CONCLUSIONS

Six surrogate indexes of IR were independently associated with incident stroke. The CVAI may be the most suitable index for stroke prediction.

Research Note: Developmental changes of glucose metabolism are associated with insulin signaling in goose embryo

This study aimed to investigate whether the developmental changes in glucose metabolism were associated with insulin signaling in the middle and later stages of goose embryos. Serum and liver were sampled on embryonic day 19, 22, 25, 28, and day of hatchment, with 30 eggs at each sampling time point, and 6 replicates of 5 embryos. The embryonic growth traits, serum glucose, hormone levels, and the hepatic mRNA expressions of target genes related to glucose metabolism and insulin signaling were measured at each time point. Relative body weight, relative liver weight, and relative body length decreased linearly and quadratically from embryonic day 19 to day of hatchment, while relative yolk weight decreased linearly from embryonic day 19 to day of hatchment. Serum glucose, insulin, and free triiodothyronine levels increased linearly with increasing incubation time, while no differences were observed in serum glucagon and free thyroxine levels. The hepatic mRNA expression related to glucose catabolism (hexokinase, phosphofructokinase, and pyruvate kinase) and insulin signaling (insulin receptor, insulin receptor substrate protein, Src homology collagen protein, extracellular signal-regulated kinase, and ribosomal protein S6 kinase, 70 ku) increased quadratically from embryonic day 19 to day of hatchment. The expression of citrate synthase and isocitrate dehydrogenase mRNA decreased linearly and quadratically respectively from embryonic day 19 to day of hatchment. Serum glucose levels were positively related to serum insulin (r = 1.00) and free triiodothyronine (r = 0.90) levels, as well as the hepatic mRNA expression of insulin receptor (r = 1.00), insulin receptor substrate protein (r = 0.64), extracellular signal-regulated kinase (r = 0.81), and ribosomal protein S6 kinase, 70 ku (r = 0.81) related to insulin signaling. In conclusion, glucose catabolism was enhanced and had positive correlations with the insulin signaling in the middle and later stages of geese embryogenesis.

Estradiol (E2) Improves Glucose-Stimulated Insulin Secretion and Stabilizes GDM Progression in a Prediabetic Mouse Model

Female New Zealand obese (NZO) mice are an established model of preconceptional (pc.) prediabetes that progresses as gestational diabetes mellitus (GDM) during gestation. It is known that NZO mice show improvement in insulin sensitivity and glucose-stimulated insulin secretion (GSIS) during gestation in vivo. The latter is no longer detectable in ex vivo perifusion experiments in isolated islets of Langerhans, suggesting a modulation by extrapancreatic factors. Here, we demonstrated that plasma 17β-estradiol (E2) levels increased markedly in NZO mice during gestation. The aim of this work was to determine whether these increased E2 levels are responsible for the improvement in metabolism during gestation. To achieve this goal, we examined its effects in isolated islets and primary hepatocytes of both NZO and metabolically healthy NMRI mice. E2 increased GSIS in the islets of both strains significantly. Hepatic glucose production (HGP) failed to be decreased by insulin in NZO hepatocytes but was reduced by E2 in both strains. Hepatocytes of pregnant NZO mice showed significantly lower glucose uptake (HGU) compared with NMRI controls, whereby E2 stimulation diminished this difference. Hepatocytes of pregnant NZO showed reduced glycogen content, increased cyclic adenosine monophosphate (cAMP) levels, and reduced AKT activation. These differences were abolished after E2 stimulation. In conclusion, our data indicate that E2 stabilizes and prevents deterioration of the metabolic state of the prediabetic NZO mice. E2 particularly increases GSIS and improves hepatic glucose utilization to a lower extent.

Role of Serotonin (5-HT) in GDM Prediction Considering Islet and Liver Interplay in Prediabetic Mice during Gestation

Gestational diabetes (GDM) is characterized by a glucose tolerance disorder. This may first appear during pregnancy or pre-exist before conception as a form of prediabetes, but there are few data on the pathogenesis of the latter subtype. Female New Zealand obese (NZO) mice serve as a model for this subpopulation of GDM. It was recently shown that GDM is associated with elevated urinary serotonin (5-hydroxytryptamine, 5-HT) levels, but the role of the biogenic amine in subpopulations with prediabetes remains unclear. 5-HT is synthesized in different tissues, including the islets of Langerhans during pregnancy. Furthermore, 5-HT receptors (HTRs) are expressed in tissues important for the regulation of glucose homeostasis, such as liver and pancreas. Interestingly, NZO mice showed elevated plasma and islet 5-HT concentrations as well as impaired glucose-stimulated 5-HT secretion. Incubation of isolated primary NZO islets with 5-HT revealed an inhibitory effect on insulin and glucagon secretion. In primary NZO hepatocytes, 5-HT aggravated hepatic glucose production (HGP), decreased glucose uptake (HGU), glycogen content, and modulated AKT activation as well as cyclic adenosine monophosphate (cAMP) increase, indicating 5-HT downstream modulation. Treatment with an HTR2B antagonist reduced this 5-HT-mediated deterioration of the metabolic state. With its strong effect on glucose metabolism, these data indicate that 5-HT is already a potential indicator of GDM before conception in mice.

Hepatic glycogen participates in the regulation of hypothalamic pAkt/Akt ratio in high-sugar/high-fat diet-induced obesity

The hypothalamus is a major integrating centre that controls energy homeostasis and plays a major role in hepatic glycogen (HGlyc) turnover. Not only do hypothalamic and hepatic Akt levels influence glucose homeostasis and glycogen synthesis, but exposure to high-sugar/high-fat diets (HSHF) can also lead to hypothalamic inflammation and HGlyc accumulation. HSHF withdrawal overall restores energy and glucose homeostasis, but the actual relationship between hypothalamic inflammation and HGlyc after short-term HSHF withdrawal has not yet been fully elucidated. Here we investigated the short-term effects of HSHF withdrawal preceded by a 30-day HSHF intake on the liver-hypothalamus crosstalk and glucose homeostasis. Sixty-day old male Wistar rats were fed for 30 days a control chow (n = 10) (Ct), or an HSHF diet (n = 20). On the 30th day of dietary intervention, a random HSHF subset (n = 10) had their diets switched to control chow for 48 h (Hw) whilst the remaining HSHF rats remained in the HSHF diet (n = 10) (Hd). All rats were anaesthetized and euthanized at the end of the protocol. We quantified HGlyc, Akt phosphorylation, inflammation and glucose homeostasis biomarkers. We also assessed the effect of propensity to obesity on those biomarkers, as detailed previously. Hd rats showed impaired glucose homeostasis, higher HGlyc and hypothalamic inflammation, and lower pAkt/Akt. Increased HGlyc was significantly associated with HSHF intake on pAkt/Akt lowered levels. We also found that HGlyc breakdown may have prevented a further pAkt/Akt drop after HSHF withdrawal. Propensity to obesity showed no apparent effect on hypothalamic inflammation or glucose homeostasis. Our findings suggest a comprehensive role of HGlyc as a structural and functional modulator of energy metabolism, and such roles may come into play relatively rapidly.

Quality More Than Quantity: The Use of Carbohydrates in High-Fat Diets to Tackle Obesity in Growing Rats

Childhood obesity prevention is important to avoid obesity and its comorbidities into adulthood. Although the energy density of food has been considered a main obesogenic factor, a focus on food quality rather that the quantity of the different macronutrients is needed. Therefore, this study investigates the effects of changing the quality of carbohydrates from rapidly to slowly digestible carbohydrates on metabolic abnormalities and its impact on obesity in growing rats fed a high-fat diet (HFD). Growing rats were fed on HFD containing carbohydrates with different digestion rates: a HFD containing rapid-digesting carbohydrates (OBE group) or slow-digesting carbohydrates (ISR group), for 4 weeks and the effect on the metabolism and signaling pathways were analyzed in different tissues. Animals from OBE group presented an overweight/obese phenotype with a higher body weight gain and greater accumulation of fat in adipose tissue and liver. This state was associated with an increase of HOMA index, serum diacylglycerols and triacylglycerides, insulin, leptin, and pro-inflammatory cytokines. In contrast, the change of carbohydrate profile in the diet to one based on slow digestible prevented the obesity-related adverse effects. In adipose tissue, GLUT4 was increased and UCPs and PPARγ were decreased in ISR group respect to OBE group. In liver, GLUT2, FAS, and SRBP1 were lower in ISR group than OBE group. In muscle, an increase of glycogen, GLUT4, AMPK, and Akt were observed in comparison to OBE group. In conclusion, this study demonstrates that the replacement of rapidly digestible carbohydrates for slowly digestible carbohydrates within a high-fat diet promoted a protective effect against the development of obesity and its associated comorbidities.

Dyrk1b promotes hepatic lipogenesis by bypassing canonical insulin signaling and directly activating mTORC2 in mice

Mutations in Dyrk1b are associated with metabolic syndrome and nonalcoholic fatty liver disease in humans. Our investigations showed that DYRK1B levels are increased in the liver of patients with nonalcoholic steatohepatitis (NASH) and in mice fed with a high-fat, high-sucrose diet. Increasing Dyrk1b levels in the mouse liver enhanced de novo lipogenesis (DNL), fatty acid uptake, and triacylglycerol secretion and caused NASH and hyperlipidemia. Conversely, knockdown of Dyrk1b was protective against high-calorie-induced hepatic steatosis and fibrosis and hyperlipidemia. Mechanistically, Dyrk1b increased DNL by activating mTORC2 in a kinase-independent fashion. Accordingly, the Dyrk1b-induced NASH was fully rescued when mTORC2 was genetically disrupted. The elevated DNL was associated with increased plasma membrane sn-1,2-diacylglyerol levels and increased PKCε-mediated IRKT1150 phosphorylation, which resulted in impaired activation of hepatic insulin signaling and reduced hepatic glycogen storage. These findings provide insights into the mechanisms that underlie Dyrk1b-induced hepatic lipogenesis and hepatic insulin resistance and identify Dyrk1b as a therapeutic target for NASH and insulin resistance in the liver.

Obesity induced Ext1 reduction mediates the occurrence of NAFLD

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder with intricate etiology. It is closely associated with metabolic syndrome, insulin resistance and endoplasmic reticulum (ER) stress. Exostosin1 (Ext1) is an ER-resident transmembrane glycosyltransferase, which plays an important role in ER homeostasis. Loss-of-function mutations in Ext1 link to hereditary multiple exostosis (HME). The present research was undertaken to identify the effect of Ext1 in the progress of NAFLD. High-fat-diet induced mice obesity, hepatic steatosis and decreased hepatic Ext1 expression. In consistent with evaluation of NAFLD mice possessing down-regulated Ext1 expression, free fatty acid (FFA) treatment blunted Ext1 expression in hepatocytes. In human subjects, HME patients presented elevated fasting blood glucose-one of the criteria that define insulin resistance. In vitro experiments, Ext1 deficiency promoted FFA-induced insulin resistance in hepatocytes by analysis of glycogen storage and hallmarks of gluconeogenesis, ascertaining its association with insulin resistance. Mechanically, Ext1 silencing exacerbated ER stress triggered by FFA, which severely disrupted autophagy in hepatocytes, and thereby accelerated the progression of NAFLD. In conclusion, our study demonstrates a beneficial role for Ext1 during the development of NAFLD, which establishes a novel correlation between Ext1 and ER stress-induced perturbations of autophagy during NAFLD progression.

Vancomycin-Induced Modulation of Gram-Positive Gut Bacteria and Metabolites Remediates Insulin Resistance in iNOS Knockout Mice

The role of oxidative and nitrosative stress has been implied in both physiology and pathophysiology of metabolic disorders. Inducible nitric oxide synthase (iNOS) has emerged as a crucial regulator of host metabolism and gut microbiota activity. The present study examines the role of the gut microbiome in determining host metabolic functions in the absence of iNOS. Insulin-resistant and dyslipidemic iNOS-/- mice displayed reduced microbial diversity, with a higher relative abundance of Allobaculum and Bifidobacterium, gram-positive bacteria, and altered serum metabolites along with metabolic dysregulation. Vancomycin, which largely depletes gram-positive bacteria, reversed the insulin resistance (IR), dyslipidemia, and related metabolic anomalies in iNOS-/- mice. Such improvements in metabolic markers were accompanied by alterations in the expression of genes involved in fatty acid synthesis in the liver and adipose tissue, lipid uptake in adipose tissue, and lipid efflux in the liver and intestine tissue. The rescue of IR in vancomycin-treated iNOS-/- mice was accompanied with the changes in select serum metabolites such as 10-hydroxydecanoate, indole-3-ethanol, allantoin, hippurate, sebacic acid, aminoadipate, and ophthalmate, along with improvement in phosphatidylethanolamine to phosphatidylcholine (PE/PC) ratio. In the present study, we demonstrate that vancomycin-mediated depletion of gram-positive bacteria in iNOS-/- mice reversed the metabolic perturbations, dyslipidemia, and insulin resistance.

Genetic Variants of Glycogen Metabolism Genes Were Associated With Liver PDFF Without Increasing NAFLD Risk

Background/Aims: The storage amount of liver glycogen could affect the liver fibrosis assessment made by MRI-based methods. However, it remained unclear whether glycogen amount could bias the estimation of liver fat content by proton density fat fraction. In this study, we aimed to investigate whether glycogen metabolism gene variants could contribute to the bias of PDFF by genetic association. Methods: We conducted an association study of the glycogen metabolism genes based on the PDFF data of 11,129 participants in the UK Biobank. The effect of the SNPs in these genes on non-alcoholic fatty liver disease was estimated by a meta-analysis of the available NAFLD case-control studies. Results: We identified significant associations of the SNPs near the genes encoding glycogen phosphorylase (PYGM and PYGL) and synthase (GYS2) with PDFF (FDR-corrected p value < 0.05). The genes encoding the regulatory proteins of glycogenolysis (PHKB, CALM2/3), glucose transporter (SLC2A1), and glucose kinase (GCK) were also associated with PDFF. The SNP rs5402 of SLC2A2 and rs547066 of PYGM were associated with NAFLD (p < 0.05) with others being insignificant. Except for the PYGM gene, the PDFF-associated SNPs showed no associations with NAFLD. In addition, the burden tests of rare variants in these genes were not significant after FDR correction. Conclusion: Liver glycogen metabolism genes associated with PDFF were not associated with NAFLD, which implicated a potential bias effect of glycogen storage on the quantification of liver fat content by PDFF.

GABA administration improves liver function and insulin resistance in offspring of type 2 diabetic rats

This study investigated the role of GABA in attenuating liver insulin resistance (IR) in type 2 diabetes parents and reducing its risk in their descendants' liver. Both sexes' rats were divided into four groups of non-diabetic control, diabetic control (DC), GABA-treated (GABA), and insulin-treated (Ins). The study duration lasted for six months and the young animals followed for four months. Consequently, hyperinsulinemic-euglycemic clamp was performed for all animals. Apart from insulin tolerance test (ITT), serum and liver lipid profile were measured in all groups. Glycogen levels, expression of Foxo1, Irs2, Akt2, and Pepck genes in the liver were assessed for all groups. Overall, GABA improved ITT, increased liver glycogen levels and decreased lipid profile, blood glucose level, and HbA1c in parents and their offspring in compared to the DC group. GIR also increased in both parents and their offspring by GABA. Moreover, the expression of Foxo1, Irs2, Akt2, and Pepck genes improved in GABA-treated parents and their descendants in compared to DC group. Results indicated that GABA reduced liver IR in both parents and their offspring via affecting their liver insulin signaling and gluconeogenesis pathways.

Splicing Factor SLU7 Prevents Oxidative Stress-Mediated Hepatocyte Nuclear Factor 4α Degradation, Preserving Hepatic Differentiation and Protecting From Liver Damage

BACKGROUND AND AIMS

Hepatocellular dedifferentiation is emerging as an important determinant in liver disease progression. Preservation of mature hepatocyte identity relies on a set of key genes, predominantly the transcription factor hepatocyte nuclear factor 4α (HNF4α) but also splicing factors like SLU7. How these factors interact and become dysregulated and the impact of their impairment in driving liver disease are not fully understood.

APPROACH AND RESULTS

Expression of SLU7 and that of the adult and oncofetal isoforms of HNF4α, driven by its promoter 1 (P1) and P2, respectively, was studied in diseased human and mouse livers. Hepatic function and damage response were analyzed in wild-type and Slu7-haploinsufficient/heterozygous (Slu7^+/- ) mice undergoing chronic (CCl₄ ) and acute (acetaminophen) injury. SLU7 expression was restored in CCl₄ -injured mice using SLU7-expressing adeno-associated viruses (AAV-SLU7). The hepatocellular SLU7 interactome was characterized by mass spectrometry. Reduced SLU7 expression in human and mouse diseased livers correlated with a switch in HNF4α P1 to P2 usage. This response was reproduced in Slu7^+/- mice, which displayed increased sensitivity to chronic and acute liver injury, enhanced oxidative stress, and marked impairment of hepatic functions. AAV-SLU7 infection prevented liver injury and hepatocellular dedifferentiation. Mechanistically we demonstrate a unique role for SLU7 in the preservation of HNF4α1 protein stability through its capacity to protect the liver against oxidative stress. SLU7 is herein identified as a key component of the stress granule proteome, an essential part of the cell's antioxidant machinery.

CONCLUSIONS

Our results place SLU7 at the highest level of hepatocellular identity control, identifying SLU7 as a link between stress-protective mechanisms and liver differentiation. These findings emphasize the importance of the preservation of hepatic functions in the protection from liver injury.

Licochalcone E improves insulin sensitivity in palmitic acid-treated HepG2 cells through inhibition of the NLRP3 signaling pathway

Our previous research demonstrated that compound licochalcone E can reduce glucose tolerance and lipid metabolism in diabetic rats, although its mechanism remains unknown. Here, we used palmitic acid (PA) to establish a PA-treated HepG2 model, and then examined glucose uptake, glucose consumption, and blood lipids to evaluate the effects of licochalcone E within the safe dose range in the model. Polymerase chain reaction (PCR) was used to detect the expression levels of key genes associated with liver gluconeogenesis; enzyme-linked immunosorbent assay (ELISA) was deployed to evaluate the concentration of inflammatory factors; and laser confocal microscopy and western blot were used to determine the levels of reactive oxygen species (ROS) and NLRP3 inflammasome signaling pathway-related proteins, respectively. Finally, molecular simulations were exploited to validate the interaction between licochalcone E and the NLRP3 inflammasome. The results demonstrated that licochalcone E showed no toxicity in the dose range of 2.5-40 μM. In this dose range, licochalcone E substantially increased the uptake and consumption of glucose in the insulin resistance model and dose-dependently reduced the concentration of total cholesterol. The PCR results indicated that licochalcone E dose-dependently reduced the expression of Glucose-6-phosphatase (G6Pase) and Phosphoenolpyruvate carboxykinase (PEPCK) genes and increased the expression of Glucose Transporter 4 (Glut4) in PA-treated HepG2. Moreover, the ELISA results revealed that licochalcone E significantly reduced the expression of TNF-α, IL-1β, and IL-18. Confocal microscopy results showed that licochalcone E dramatically reduced the generation of ROS and the expressions of NLRP3 and its downstream caspase-1 in PA-treated HepG2 model. Western blot results further indicated that licochalcone E significantly reduced the expression of NLRP3, caspase-1 and IL-1β in the model. Additionally, molecular simulations demonstrated that licochalcone E has good binding affinity for the NLPR3 inflammasome. We concluded that licochalcone E has the potential to be used as an insulin sensitizer by reducing the release of ROS and inflammatory factors following inhibition of the NLPR3 signaling pathway.

Mechanisms and disease consequences of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the leading chronic liver disease worldwide. Its more advanced subtype, nonalcoholic steatohepatitis (NASH), connotes progressive liver injury that can lead to cirrhosis and hepatocellular carcinoma. Here we provide an in-depth discussion of the underlying pathogenetic mechanisms that lead to progressive liver injury, including the metabolic origins of NAFLD, the effect of NAFLD on hepatic glucose and lipid metabolism, bile acid toxicity, macrophage dysfunction, and hepatic stellate cell activation, and consider the role of genetic, epigenetic, and environmental factors that promote fibrosis progression and risk of hepatocellular carcinoma in NASH.

Iron status influences non-alcoholic fatty liver disease in obesity through the gut microbiome

BACKGROUND

The gut microbiome and iron status are known to play a role in the pathophysiology of non-alcoholic fatty liver disease (NAFLD), although their complex interaction remains unclear.

RESULTS

Here, we applied an integrative systems medicine approach (faecal metagenomics, plasma and urine metabolomics, hepatic transcriptomics) in 2 well-characterised human cohorts of subjects with obesity (discovery n = 49 and validation n = 628) and an independent cohort formed by both individuals with and without obesity (n = 130), combined with in vitro and animal models. Serum ferritin levels, as a markers of liver iron stores, were positively associated with liver fat accumulation in parallel with lower gut microbial gene richness, composition and functionality. Specifically, ferritin had strong negative associations with the Pasteurellaceae, Leuconostocaceae and Micrococcaea families. It also had consistent negative associations with several Veillonella, Bifidobacterium and Lactobacillus species, but positive associations with Bacteroides and Prevotella spp. Notably, the ferritin-associated bacterial families had a strong correlation with iron-related liver genes. In addition, several bacterial functions related to iron metabolism (transport, chelation, heme and siderophore biosynthesis) and NAFLD (fatty acid and glutathione biosynthesis) were also associated with the host serum ferritin levels. This iron-related microbiome signature was linked to a transcriptomic and metabolomic signature associated to the degree of liver fat accumulation through hepatic glucose metabolism. In particular, we found a consistent association among serum ferritin, Pasteurellaceae and Micrococcacea families, bacterial functions involved in histidine transport, the host circulating histidine levels and the liver expression of GYS2 and SEC24B. Serum ferritin was also related to bacterial glycine transporters, the host glycine serum levels and the liver expression of glycine transporters. The transcriptomic findings were replicated in human primary hepatocytes, where iron supplementation also led to triglycerides accumulation and induced the expression of lipid and iron metabolism genes in synergy with palmitic acid. We further explored the direct impact of the microbiome on iron metabolism and liver fact accumulation through transplantation of faecal microbiota into recipient's mice. In line with the results in humans, transplantation from 'high ferritin donors' resulted in alterations in several genes related to iron metabolism and fatty acid accumulation in recipient's mice.

CONCLUSIONS

Altogether, a significant interplay among the gut microbiome, iron status and liver fat accumulation is revealed, with potential significance for target therapies. Video abstract.

Vanillic acid mitigates the impairments in glucose metabolism in HepG2 cells through BAD-GK interaction during hyperinsulinemia

Glucokinase (GK), a key regulator of hepatic glucose metabolism in the liver and glucose sensor and mediator in the secretion of insulin in the pancreas, is not studied in detail for its therapeutic application in diabetes. Herein, we study the alteration in GK activity during hyperinsulinemia-induced insulin resistance in HepG2 cells. We also investigated the link between GK and Bcl-2-associated death receptor (BAD) during hyperinsulinemia. There are emerging demands for GK activators from natural resources, and we selected vanillic acid (VA) to evaluate its potential as GK activators during hyperinsulinemia in HepG2 cells. VA is a phenolic compound and a commonly used food additive in many food industries. We found that VA safeguarded GK inhibition during hyperinsulinemia significantly in HepG2 cells. VA also prevented the depletion of glycogen synthesis during hyperinsulinemia, which is evident from protein expression studies of phosphoenolpyruvate carboxykinase, glucose-6-phosphatase, glycogen synthase, and glycogen synthase kinase-3β. This was associated with activation of BAD activity, which was also confirmed by Western blotting. Molecular docking revealed strong binding between GK active site and VA, supporting their strong interaction. These are the first in vitro data to indicate the beneficial properties of VA with respect to insulin resistance induced by hyperinsulinemia by GK activation. Since it is activated via BAD, the hypoglycemia associated with general GK activation is not expected here and therefore has significant implications for future therapies against diabetes.

Efficacy of a Novel Herbal Formulation (F2) on the Management of Obesity: In Vitro and In Vivo Study

Background

Currently, obesity and its comorbidities have become a serious threat to human health necessitating urgent development of safe and effective therapy for their management.

Materials and Methods

In this research, a novel polyherbal formulation (F2) was prepared by mixing specific proportions of royal jelly and lemon juice with ethanol extracts of Orostachys japonicus, Rhus verniciflua, and Geranium thunbergii. The antioxidant activity was assessed using DPPH and ABTS assay methods. The antiobesity potential of the F2 was assessed in vitro using 3T3-L1 fibroblast and in vivo using a high-fat diet (HFD) fed C57BL/6J mice model. F2 was administered in mice at the dose of 23 mg/kg and 46 mg/kg, twice daily by oral gavage. A well-accepted antiobesity agent, Garcinia cambogia (GC), at 200 mg/kg was used as a positive control.

Results

F2 was observed to exhibit synergistic antiadipogenic activity in 3T3-L1 cells. This inhibition was reinforced by the downregulation of specific adipogenic transcription factors. Furthermore, F2 was also found to reduce mice body weight gain, food efficiency ratio, fasting blood glucose level, fat deposition into the liver, and mass of white adipose tissue. F2 also played a role in the excretion of fat consumed by the mice. For most of the assays performed, the F2 (46 mg/kg) was comparable to the positive control GC (200 mg/kg). In addition, potential and synergistic antioxidant activity was observed on F2.

Conclusion

The results revealed that the formulation F2 exhibited potential antiobesity activity through the inhibition of adipocyte differentiation, dietary fat absorption, and reduction of free fatty acids deposition in tissues.

Sex differences in growth performance are related to cecal microbiota in chicken

In poultry industry, male chickens have a better growth performance than female ones under the same genetic background and diet. Emerging evidences proposed an important role of intestinal microbiota in chicken's growth performance. This study aimed to determine gut microbiota related gender based differences in the growth performance of chickens. Therefore, male and female chickens (n = 20) at 7-week age were used to carry out histomorphological, molecular, gene expression analysis with their liver, chest and leg muscle, as well as 16S rRNA sequencing analysis for gut microbiota. The results revealed that Bacteroides and Megamonas genera were more prominently colonized in the cecum of male chickens. The male chicken's cecal microbiota indicated a closer relation with glycan metabolism, while in the female chickens it was more related with lipid metabolism. Gene expression levels associated with glycan and lipid metabolism were different between male and female chickens. Further, using Spearman correlation analysis, we found a positive correlation between glycan and lipid metabolism, and the relative abundance of Bacteroides, Megamona and Lactobacillus in male chickens. Similarly, we also found a positive correlation between the lipid metabolism and the relative abundance of Ruminococcaceae and Enterococcus in female chickens. These findings revealed the association of chicken growth performance with cecal microbiota that contributed to the metabolism of glycan and lipid in a sex-dependent manner.

Liver Phosphoenolpyruvate Carboxykinase-1 Downregulation via siRNA-Functionalized Graphene Oxide Nanosheets Restores Glucose Homeostasis in a Type 2 Diabetes Mellitus In Vivo Model

Metabolic disorders have been increasing at an alarming rate, and one such example of metabolic disorder is type 2 diabetes mellitus (T2DM). Unregulated gluconeogenesis in T2DM results in increased hepatic glucose output that causes fasting and postprandial hyperglycaemia. Extensive proofs have shown that the downregulation of the key rate-limiting enzyme phosphoenolpyruvate carboxykinase-1 (PCK-1) of gluconeogenesis improved glucose homeostasis in vivo. In the present study, we have synthesized and characterized liver-specific stearic acid conjugated octaarginine (StA-R8) functionalized 4arm-2K-PEGamineylated graphene oxide nanosheets (GPR8) for the delivery of siRNA against PCK-1 in T2DM C57BL/6 mice. We found that a single intravenous administration of siRNA (3 mg/kg BW) conjugated to GPR8 (GPR8:PCK-1_{siRNA(3 mg/kg BW)} conjugate) in an optimized N/P ratio exploited as a therapeutic nanoformulation maintained glucose homeostasis for nearly 4 weeks in the T2DM mice. Efficient silencing of PCK-1 in T2DM liver tissue increased the phosphorylation of serine-256 of FOXO-1, thus showing a marked decrease in hepatic gluconeogenesis. Gluconeogenesis control and consequently glucose output from the liver furthermore partially enhanced liver and muscle insulin sensitivity results in the stimulation of the insulin/AKT-2 signaling pathway which indirectly restored glucose homeostasis in the treated T2DM group. Our therapeutic nanoformulation also improved glycogen storage in the liver and membrane translocation of GLUT4 in the muscle of the treated T2DM group. In conclusion, GPR8:PCK-1_{siRNA (3 mg/Kg BW)} restored glucose homeostasis by controlling the hepatic glucose production and improved peripheral insulin sensitivity as a consequence of reduced hyperglycemia. Thus, the current approach offered an alternative strategy for the therapeutics for T2DM.

Hepatotoxicity induced by nanomaterials: mechanisms and in vitro models

The unique physicochemical properties of materials at nanoscale have opened a plethora of opportunities for applications in the pharmaceutical and medical field, but also in consumer products from food and cosmetics industries. As a consequence, daily human exposure to nanomaterials through distinct routes is considerable and, therefore, may raise health concerns. Many nanomaterials have been described to accumulate and induce adversity in the liver. Among these, silica and some types of metallic nanoparticles are the most broadly used in consumer products and, therefore, the most studied and reported. The reviewed literature was collected from PubMed.gov during the month of March 2020 using the search words "nanomaterials induced hepatotoxicity", which yielded 181 papers. This present paper reviews the hepatotoxic effects of nanomaterials described in in vitro and in vivo studies, with emphasis on the underlying mechanisms. The induction of oxidative stress and inflammation are the manifestations of toxicity most frequently reported following exposure of cells or animal models to different nanomaterials. Furthermore, the available in vitro models for the evaluation of the hepatotoxic effects of nanomaterials are discussed, highlighting the continuous interest in the development of more advanced and reliable in vitro models for nanotoxicology.

The Multifunctionality of CD36 in Diabetes Mellitus and Its Complications-Update in Pathogenesis, Treatment and Monitoring

CD36 is a multiligand receptor contributing to glucose and lipid metabolism, immune response, inflammation, thrombosis, and fibrosis. A wide range of tissue expression includes cells sensitive to metabolic abnormalities associated with metabolic syndrome and diabetes mellitus (DM), such as monocytes and macrophages, epithelial cells, adipocytes, hepatocytes, skeletal and cardiac myocytes, pancreatic β-cells, kidney glomeruli and tubules cells, pericytes and pigment epithelium cells of the retina, and Schwann cells. These features make CD36 an important component of the pathogenesis of DM and its complications, but also a promising target in the treatment of these disorders. The detrimental effects of CD36 signaling are mediated by the uptake of fatty acids and modified lipoproteins, deposition of lipids and their lipotoxicity, alterations in insulin response and the utilization of energy substrates, oxidative stress, inflammation, apoptosis, and fibrosis leading to the progressive, often irreversible organ dysfunction. This review summarizes the extensive knowledge of the contribution of CD36 to DM and its complications, including nephropathy, retinopathy, peripheral neuropathy, and cardiomyopathy.

Hepatocyte TMEM16A Deletion Retards NAFLD Progression by Ameliorating Hepatic Glucose Metabolic Disorder

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent form of chronic liver disease, and the mechanisms underpinning its pathogenesis have not been completely established. Transmembrane member 16A (TMEM16A), a component of the Ca2+-activated chloride channel (CaCC), has recently been implicated in metabolic events. Herein, TMEM16A is shown to be responsible for CaCC activation in hepatocytes and is increased in liver tissues of mice and patients with NAFLD. Hepatocyte-specific ablation of TMEM16A in mice ameliorates high-fat diet-induced obesity, hepatic glucose metabolic disorder, steatosis, insulin resistance, and inflammation. In contrast, hepatocyte-specific TMEM16A transgenic mice exhibit the opposite phenotype. Mechanistically, hepatocyte TMEM16A interacts with vesicle-associated membrane protein 3 (VAMP3) to induce its degradation, suppressing the formation of the VAMP3/syntaxin 4 and VAMP3/synaptosome-associated protein 23 complexes. This leads to the impairment of hepatic glucose transporter 2 (GLUT2) translocation and glucose uptake. Notably, VAMP3 overexpression restrains the functions of hepatocyte TMEM16A in blocking GLUT2 translocation and promoting lipid deposition, insulin resistance, and inflammation. In contrast, VAMP3 knockdown reverses the beneficial effects of TMEM16A downregulation. This study demonstrates a role for TMEM16A in NAFLD and suggests that inhibition of hepatic TMEM16A or disruption of TMEM16A/VAMP3 interaction may provide a new potential therapeutic strategy for NAFLD.

A mixture of mulberry and silk amino acids protected against D-galactosamine induced acute liver damage by attenuating oxidative stress and inflammation in HepG2 cells and rats

The liver is an important organ for the removal of toxins and utilization of nutrients. The present study then investigated whether a mixture of mulberry water extracts and silk amino acids protected against acute liver damage in rats induced by intraperitoneal injection of D-galactosamine and the action mechanism. D-galactosamine injection is widely used to develop experimental animal models of acute hepatic disease. In the present study, male Sprague-Dawley rats received intraperitoneal injection of D-galactosamine followed by 200 and 600 mg/kg body weight (BW) of mulberry extracts and silk amino acids (1:3, w/w; MS1:3-L and MS1:3-H), the same amounts of MS with different ratios (1:5, w/w; MS1:5-L and MS1:5-H), and 600 mg/kg bw cellulose (control) for 1 week. The normal-control group received an injection of saline instead of D-galactosamine with the same diet as the control group. D-galactosamine injection (control rats) increased serum ALT, AST and γ-GPT levels, indicating the induction of acute liver damage. The control rats also exhibited reduced glycogen depositions, which contributed to increasing fat synthesis from glucose and elevated serum triglyceride levels. Oxidative stress and inflammation in the liver of the control increased in response to the decreasing antioxidant activity and mRNA expression and increasing TNF-α expression, respectively. Both MS1:3 and MS1:5 reduced serum ALT, AST and γ-GPT levels to ameliorate liver damage. MS1:3 reduced oxidative stress by increasing the activity and expression of antioxidant enzymes, whereas MS1:5 decreased the expression TNF-α in the liver. MS1:3 and MS1:5 improved the necrosis of hepatocytes in H&E staining, which was associated with increased glycogen deposition in PAS staining. MS1:5 had better effects on glycogen accumulation. In conclusion, MS1:3 and MS1:5 can be used as therapeutic agents for acute liver damage.

A Retrospective Population Study to Develop a Predictive Model of Prediabetes and Incident Type 2 Diabetes Mellitus from a Hospital Database in Japan Between 2004 and 2015

Background

Type 2 diabetes mellitus is a global public health problem. Prediabetes may be reversed by weight loss, diet, and lifestyle changes. However, without intervention, between 30–50% of individuals with prediabetes develop type 2 diabetes. This retrospective population study was conducted to develop a predictive model of prediabetes and incident type 2 diabetes mellitus using data from 2004 to 2015 from the DRYAD Japanese hospital database.

Material/Methods

A retrospective longitudinal population study was conducted using the DRYAD database from Murakami Memorial Hospital, Gifu, Japan, to construct a predictive model for prediabetes and incident type 2 diabetes mellitus in the population. Univariate analysis and multivariate analysis were performed to identify the variables that were associated with prediabetes. These variables were used to construct (75% samples) and verify (25% samples) the predictive model.

Results

From 2004 to 2015, a total of 11,113 cases were identified. Multivariate logistic regression analysis included the six variables of age, waist circumference, smoking history, the presence of fatty liver, fasting blood glucose (FBG), and glycated hemoglobin (HbA1c) level. Data were used to construct (75% samples) and verify (25% samples) in a predictive model. The area under the receiver operating characteristic (ROC) curve (AUC) of the predictive model was 0.87 (0.85–0.89) in the training cohort and 0.87 (0.86–0.90) in the validation cohort.

Conclusions

A prognostic model based on six variables was predictive for incident type 2 diabetes mellitus and prediabetes in a healthy population in Japan.

Maintenance of liver glycogen during long-term fasting preserves energy state in mice

Glycogen shortage during fasting coincides with dramatic changes in hepatic adenine nucleotide levels. The aim of this work was to study the relevance of liver glycogen in the regulation of the hepatic energy state during food deprivation. To this end, we examined the response of mice with sustained increased liver glycogen content to prolonged fasting. In order to increase hepatic glycogen content, we generated mice that overexpress protein targeting to glycogen (PTG) in the liver (PTG^OE  mice). Control and PTG^OE  mice were fed ad libitum or fasted for 36 h. Upon fasting, PTG^OE  mice retained significant hepatic glycogen stores and maintained hepatic energy status. Furthermore, we show that liver glycogen controls insulin sensitivity, gluconeogenesis, lipid metabolism, and ketogenesis upon nutrient deprivation.

Secondhand Smoke Induces Liver Steatosis through Deregulation of Genes Involved in Hepatic Lipid Metabolism

We investigated the role of secondhand smoke (SHS) exposure, independently of diet, in the development of chronic liver disease. Standard diet-fed mice were exposed to SHS (5 h/day, 5 days/week for 4 months). Genome-wide gene expression analysis, together with molecular pathways and gene network analyses, and histological examination for lipid accumulation, inflammation, fibrosis, and glycogen deposition were performed on the liver of SHS-exposed mice and controls, upon termination of exposure and after one-month recovery in clean air. Aberrantly expressed transcripts were found in the liver of SHS-exposed mice both pre- and post-recovery in clean air (n = 473 vs. 222). The persistent deregulated transcripts (n = 210) predominantly affected genes and functional networks involved in lipid metabolism as well as in the regulation of the endoplasmic reticulum where manufacturing of lipids occurs. Significant hepatic fat accumulation (steatosis) was observed in the SHS-exposed mice, which progressively increased as the animals underwent recovery in clean air. Moderate increases in lobular inflammation infiltrates and collagen deposition as well as loss of glycogen were also detectable in the liver of SHS-exposed mice. A more pronounced phenotype, manifested as a disrupted cord-like architecture with foci of necrosis, apoptosis, inflammation, and macrovesicular steatosis, was observed in the liver of SHS-exposed mice post-recovery. The progressive accumulation of hepatic fat and other adverse histological changes in the SHS-exposed mice are highly consistent with the perturbation of key lipid genes and associated pathways in the corresponding animals. Our data support a role for SHS in the genesis and progression of metabolic liver disease through deregulation of genes and molecular pathways and functional networks involved in lipid homeostasis.