Regulation of hepatic glucose metabolism in health and disease

Evaluation of Hepatic Glucose and Palmitic Acid Metabolism in Rodents on High-Fat Diet Using Deuterium Metabolic Imaging

BACKGROUND

One of the main features of several metabolic disorders is dysregulation of hepatic glucose and lipid metabolism. Deuterium metabolic imaging (DMI) allows for assessing the uptake and breakdown of 2H-labeled substrates, giving specific insight into nutrient processing in healthy and diseased organs. Thus, DMI could be a useful approach for analyzing the differences in liver metabolism of healthy and diseased subjects to gain a deeper understanding of the alterations related to metabolic disorders.

PURPOSE

Evaluating the feasibility of DMI as a tool for the assessment of metabolic differences in rodents with healthy and fatty livers (FLs).

STUDY TYPE

Animal Model.

POPULATION

18 male Sprague Dawley rats on standard (SD, n = 9, healthy) and high-fat diet (HFD, n = 9, FL disease).

FIELD STRENGTH/SEQUENCE

Phase-encoded 1D pulse-acquire sequence and anatomy co-registered phase-encoded 3D pulse-acquire chemical shift imaging for 2H at 9.4T.

ASSESSMENT

Localized and nonlocalized liver spectroscopy was applied at eight time points over 104 minutes post injection. The obtained spectra were preprocessed and quantified using jMRUI (v7.0) and the resulting amplitudes translated to absolute concentration (mM) according to the 2H natural abundance water peak.

STATISTICAL TESTS

Two-way repeated measures ANOVA were employed to assess between-group differences, with statistical significance at P < 0.05.

RESULTS

DMI measurements demonstrated no significant difference (P = 0.98) in the uptake of [6,6'-2H2]glucose between healthy and impaired animals (AUCSD = 1966.0 ± 151.5 mM - minutes vs. AUCHFD = 2027.0 ± 167.6 mM·minutes). In the diseased group, the intrahepatic uptake of palmitic acid d-31 was higher (AUCHFD = 57.4 ± 17.0 mM·minutes, AUCSD = 33.3 ± 10.5 mM·minutes), but without statistical significance owing to substantial in-group variation (P = 0.73).

DATA CONCLUSION

DMI revealed higher concentrations of palmitic acid in rats with FL disease and no difference in hepatic glucose concentration between healthy and impaired animals. Thus, DMI appears to be a useful tool for evaluating metabolism in rodents with FL disease.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 3.

Bioinert UHPLC system improves sensitivity and peak shapes for ionic metabolites

The analysis of ionic compounds by liquid chromatography is challenging due to the interaction of analytes with the metal surface of the instrument and the column, leading to poor peak shape and decreased sensitivity. The use of bioinert materials in the chromatographic system minimizes these unrequired interactions. In this work, the ultrahigh-performance liquid chromatography (UHPLC) with bioinert components was connected to a high-resolution mass spectrometer to develop a method for untargeted metabolomic analysis. 81 standards of metabolites were used for the development and optimization of the method. In comparison to the conventional chromatographic system, the application of bioinert technology resulted in significantly improved peak shapes and increased sensitivity, especially for metabolites containing phosphate groups. The calibration curves were constructed for the evaluation of the method performance, showing a wide dynamic range, low limit of detection, and linear regression coefficients higher than 0.99 for all standards. The optimized method was applied to the analysis of NIST SRM 1950 human plasma, which allowed the detection of 156 metabolites and polar lipids based on the combination of mass accuracy in the full-scan mass spectra in both polarity modes, characteristic fragment ions in MS/MS, and logical chromatographic behavior leading to the high confidence level of annotation/identification. We have demonstrated an improvement in the peak shapes and sensitivity of ionic metabolites using bioinert technology, which indicates the potential for the analysis of other ionic compounds, e.g., molecules containing phosphate groups.

A feeding-induced myokine modulates glucose homeostasis

Maintaining blood glucose homeostasis during fasting and feeding is crucial for the prevention of dysregulation that can lead to either hypo- or hyperglycaemia. Here we identified feimin, encoded by a gene with a previously unknown function (B230219D22Rik in mice, C5orf24 in humans), as a key modulator of glucose homeostasis. Feimin is secreted from skeletal muscle during feeding and binds to its receptor, receptor protein tyrosine kinase Mer (MERTK), promoting glucose uptake and inhibiting glucose production by activation of AKT. Administration of feimin and insulin synergistically improves blood glucose homeostasis in both normal and diabetic mice. Notably, a specific single nucleotide polymorphism (rs7604639, G>A) within the MERTK gene, causing an amino acid substitution (R466K) within the feimin-MERTK binding region, leads to reduced association with feimin and elevated postprandial blood glucose and insulin levels in humans. Our findings underscore a role of the feimin-MERTK signalling axis in glucose homeostasis, providing valuable insights into potential therapeutic avenues for diabetes.

ZBED3 exacerbates hyperglycemia by promoting hepatic gluconeogenesis through CREB signaling

BACKGROUND

Elevated hepatic glucose production (HGP) is a prominent manifestation of impaired hepatic glucose metabolism in individuals with diabetes. Increased hepatic gluconeogenesis plays a pivotal role in the dysregulation of hepatic glucose metabolism and contributes significantly to fasting hyperglycemia in diabetes. Previous studies have identified zinc-finger BED domain-containing 3 (ZBED3) as a risk gene for type 2 diabetes (T2DM), and its single nucleotide polymorphism (SNPs) is closely associated with the fasting blood glucose level, suggesting a potential correlation between ZBED3 and the onset of diabetes. This study primarily explores the effect of ZBED3 on hepatic gluconeogenesis and analyzes the relevant signaling pathways that regulate hepatic gluconeogenesis.

METHODS

The expression level of ZBED3 was assessed in the liver of insulin-resistant (IR)-related disease. RNA-seq and bioinformatics analyses were employed to examine the ZBED3-related pathway that modulated HGP. To investigate the role of ZBED3 in hepatic gluconeogenesis, the expression of ZBED3 was manipulated by upregulation or silencing using adeno-associated virus (AAV) in mouse primary hepatocytes (MPHs) and HHL-5 cells. In vivo, hepatocyte-specific ZBED3 knockout mice were generated. Moreover, AAV8 was employed to achieve hepatocyte-specific overexpression and knockdown of ZBED3 in C57BL/6 and db/db mice. Immunoprecipitation and mass spectrometry (IP-MS) analyses were employed to identify proteins that interacted with ZBED3. Co-immunoprecipitation (co-IP), glutathione S-transferase (GST) - pulldown, and dual-luciferase reporter assays were conducted to further elucidate the underlying mechanism of ZBED3 in regulating hepatic gluconeogenesis.

RESULTS

The expression of ZBED3 in the liver of IR-related disease models was found to be increased. Under the stimulation of glucagon, ZBED3 promoted the expression of hepatic gluconeogenesis-related genes PGC1A, PCK1, G6PC, thereby increasing HGP. Consistently, the rate of hepatic gluconeogenesis was found to be elevated in mice with hepatocyte-specific overexpression of ZBED3 and decreased in those with ZBED3 knockout. Additionally, the knockdown of ZBED3 in the liver of db/db mice resulted in a reduction in hepatic gluconeogenesis. Moreover, the study revealed that ZBED3 facilitated the nuclear translocation of protein arginine methyltransferases 5 (PRMT5) to influence the regulation of PRMT5-mediated symmetrical dimethylation of arginine (s-DMA) of cyclic adenosine monophosphate (cAMP) response element binding protein (CREB), which in turn affects the phosphorylation of CREB and ultimately promotes HGP.

CONCLUSIONS

This study indicates that ZBED3 promotes hepatic gluconeogenesis and serves as a critical regulator of the progression of diabetes.

Enhancing metabolic and inflammatory status in insulin-resistant rats: Acute intervention with cocoa flavanols and submaximal aerobic exercise activates intracellular signaling pathways for glucose metabolism

INTRODUCTION

Type 2 diabetes, characterized by hyperglycemia, is closely linked to obesity and low-grade inflammation. Acute cocoa flavanols (CF) intake has demonstrated benefits in vasoreactivity, cognitive functions, and antioxidant enzyme activity. However, the physiological mechanisms of CF concerning glucose uptake, inflammatory mediators, and their interplay with aerobic exercise remain unclear in populations with metabolic diseases.

OBJECTIVE

This study aims to investigate the acute effects of CF, alone or combined with acute aerobic exercise on mechanisms involved in glucose uptake and inflammatory mediators in the liver, skeletal muscle, pancreas, and adipose tissue in insulin-resistant (IR) rats.

METHODS

Sixty-four Wistar rats (250 ± 10g; 15 weeks age) were subjected to a regular chow (CON) or an obesity-associated insulin-resistant (IR) state induced by a high-fat diet and fructose-rich beverage for 30 days. Seventy-two hours after an incremental maximal treadmill running test, rats received a placebo solution or CF supplementation (45 mg·kg-1 of body weight). One hour later, they either rested or ran on a treadmill at 60 % of peak oxygen uptake (VO2peak) for 30 min. Euthanasia occurred 30 min post-experimental sessions. Inflammatory and anti-inflammatory cytokines were assayed using ELISA in the liver, pancreas, gastrocnemius muscle, and epididymal adipose tissues. TRB3 and CPT1 mRNA were assessed by q-RTPCR in the liver and gastrocnemius muscle while Akt and AMPK phosphorylation were examined by immunohistochemistry.

RESULTS

CF attenuated hyperglycemia observed after submaximal aerobic exercise in IR rats (p < 0.001). In the liver, CF exhibited additive effects to aerobic exercise, enhancing Akt protein phosphorylation, potentially contributing to improved glucose uptake in IR rats. Submaximal aerobic exercise and CF increased AMPK protein phosphorylation in the liver (p < 0.001) and skeletal muscle (p < 0.001), reduced TRB3 gene expression (p < 0.01), elevated CPT-1a gene expression (p < 0.001), and ameliorated the inflammatory milieu in the pancreas, adipose tissue, liver, and gastrocnemius muscle.

CONCLUSION

Acute intake, of CF combined with submaximal aerobic exercise activates key proteins and genes involved in glucose uptake and lipid metabolism, improving the inflammatory milieu. This synergistic effect may contribute to mitigating metabolic complications associated with insulin resistance.

Integrated hepatic transcriptomics and metabolomics identify Pck1 as a key factor in the broad dysregulation induced by vehicle pollutants

BACKGROUND

Exposure to air pollution is associated with worldwide morbidity and mortality. Diesel exhaust (DE) emissions are important contributors which induce vascular inflammation and metabolic disturbances by unknown mechanisms. We aimed to determine molecular pathways activated by DE in the liver that could be responsible for its cardiometabolic toxicity.

METHODS

Apolipoprotein E knockout (ApoE KO) mice were exposed to DE or filtered air (FA) for two weeks, or DE for two weeks followed by FA for 1 week. Expression microarrays and global metabolomics assessment were performed in the liver. An integrated transcriptomic and metabolomic analytical strategy was employed to dissect critical pathways and identify candidate genes that could dissect DE-induced pathogenesis. HepG2 cells were treated with an organic extract of DE particles (DEP) vs. vehicle control to test candidate genes.

RESULTS

DE exposure for 2 weeks dysregulated 658 liver genes overrepresented in whole cell metabolic pathways, especially including lipid and carbohydrate metabolism, and the respiratory electron transport pathway. DE exposure significantly dysregulated 118 metabolites, resulting in increased levels of triglycerides and fatty acids due to mitochondrial dysfunction as well as increased levels of glucose and oligosaccharides. Consistently, DEP treatment of HepG2 cells led to increased gluconeogenesis and glycogenolysis indicating the ability of the in-vitro approach to model effects induced by DE in vivo. As an example, while gene network analysis of DE livers identified phosphoenolpyruvate carboxykinase 1 (Pck1) as a key driver gene of DE response, DEP treatment of HepG2 cells resulted in increased mRNA expression of Pck1 and glucose production, the latter replicated in mouse primary hepatocytes. Importantly, Pck1 inhibitor mercaptopicolinic acid suppressed DE-induced glucose production in HepG2 cells indicating that DE-induced elevation of hepatic glucose was due in part to upregulation of Pck1 and increased gluconeogenesis.

CONCLUSIONS

Short-term exposure to DE induced widespread alterations in metabolic pathways in the liver of ApoE KO mice, especially involving carbohydrate and lipid metabolism, together with mitochondrial dysfunction. Pck1 was identified as a key driver gene regulating increased glucose production by activation of the gluconeogenesis pathway.

Phenotypic screening in zebrafish larvae identifies promising cyanobacterial strains and pheophorbide a as insulin mimetics

Diabetes is a pandemic disease that causes the loss of control of glucose regulation in the organism, in consequence of dysfunction of insulin production or functionality. In this work, the antidiabetic bioactivity of 182 fractions from 19 cyanobacteria strains derived from the LEGE Culture Collection were analysed using the 2-NBDG assay in zebrafish larvae. From this initial screening, two fractions (57 (06104_D) and 107 (03283_B)) were identified as promising insulin mimetics. These were further characterized by measuring glucose levels in whole larvae, the expression of glucose transporters (GLUT 1-3) using western blot, and the mRNA expression levels of the glut2, pepck, and insa genes using real-time qPCR. Both fractions showed a decrease in free glucose levels. Furthermore, exposure to fraction 06104_D decreased GLUT1 and increased insa mRNA levels. The chemical composition of these fractions was determined using LC-HRESIMS/MS and compared to inactive fractions of the same polarity in order to identify the unique bioactive molecules. The molecular networks constructed using the GNPS platform revealed that fraction 06104_D contained mass clusters primarily composed of chlorins, lipids, and terpenoids, while fraction 03283_B contained xanthophylls, peptides, and terpenoids. To correlate the observed activity with the chemical composition of fraction 06104_D, pheophorbide a was chosen as a representative of chlorophyll derivatives. Exposure to zebrafish larvae at 10 and 20 µM confirmed the increased glucose uptake on the 2-NBDG assay. These findings highlight the bioactivity of chlorophyll derivatives as insulin mimetic compounds, as well as cyanobacteria as a source of potential therapeutic diabetes applications.

Gegen Qinlian Decoction inhibits liver ferroptosis in type 2 diabetes mellitus models by targeting Nrf2

ETHNOPHARMACOLOGICAL RELEVANCE

Type 2 diabetes mellitus (T2DM) is a metabolic disease that can lead to complications affecting multiple organs, including the liver. Gegen Qinlian Decoction (GQD) has demonstrated considerable efficacy in the management of T2DM and its complications in accordance with the tenets of modern Chinese medicine. However, the molecular mechanism by which GQD alleviates diabetic liver injury is unclear.

AIM OF THE STUDY

To explore the effect and mechanism of GQD to ameliorate liver injury in T2DM.

MATERIALS AND METHODS

The active constituents of GQD were analyzed using UPLC. An in vivo T2DM mouse model was established by 6 weeks of high-fat diet and multiple streptozotocin (50 mg/kg/day) induction, followed by GQD administration. The evaluation of liver function, histopathology, oxidative stress, lipid peroxidation, and iron levels was conducted. In vitro experiments involved a high-glucose-induced AML12 cell model to assess oxidative stress, lipid peroxidation, and iron levels.

RESULTS

UPLC identified four main components in GQD: puerarin, baicalin, berberine and liquiritin. GQD administration resulted in enhanced liver function and a reduction in injury, accompanied by elevated antioxidant enzyme activity, increased GPX4 expression and diminished reactive oxygen species in T2DM mice. GQD treatment reduced lipid peroxidation and regulated iron transport proteins, thereby alleviating iron overload. In AML12 cells, GQD administration resulted in regulated mitochondrial morphology.

CONCLUSION

Our findings demonstrated that GQD ameliorated liver injury in T2DM by inhibiting ferroptosis through the modulation of Nrf2.

Prediction of metabolic subphenotypes of type 2 diabetes via continuous glucose monitoring and machine learning

The classification of type 2 diabetes and prediabetes does not consider heterogeneity in the pathophysiology of glucose dysregulation. Here we show that prediabetes is characterized by metabolic heterogeneity, and that metabolic subphenotypes can be predicted by the shape of the glucose curve measured via a continuous glucose monitor (CGM) during standardized oral glucose-tolerance tests (OGTTs) performed in at-home settings. Gold-standard metabolic tests in 32 individuals with early glucose dysregulation revealed dominant or co-dominant subphenotypes (muscle or hepatic insulin-resistance phenotypes in 34% of the individuals, and β-cell-dysfunction or impaired-incretin-action phenotypes in 40% of them). Machine-learning models trained with glucose time series from OGTTs from the 32 individuals predicted the subphenotypes with areas under the curve (AUCs) of 95% for muscle insulin resistance, 89% for β-cell deficiency and 88% for impaired incretin action. With CGM-generated glucose curves obtained during at-home OGTTs, the models predicted the muscle-insulin-resistance and β-cell-deficiency subphenotypes of 29 individuals with AUCs of 88% and 84%, respectively. At-home identification of metabolic subphenotypes via a CGM may aid the risk stratification of individuals with early glucose dysregulation.

Clerodane diterpenoids from the vine stems of Fibraurea recisa Pierre and their hepatic gluconeogenesis inhibitory activity

Fibraurea recisa Pierre is a vine plant and its vine stems are used as a traditional Chinese medicine to treat heat toxin, constipation, diarrhea, sore throat, eye inflammation, carbuncles, and skin ulcers. The alkaloid chemical composition of this plant has been extensively studied; however, investigations into non-alkaloid components remain limited. In this study, phytochemical studies of the vine stems of F. recisa were conducted, leading to the isolation and identification of twenty highly oxidized clerodane diterpenoids, including ten previously undescribed compounds, designated fibrecins A-J (1-10). The structures and absolute configurations of 1-10 were determined through comprehensive spectroscopic methods (IR, HRESIMS, 1D and 2D NMR), electronic circular dichroism data, and single-crystal X-ray diffraction. Notably, compounds 1 and 2 are rare 18-nor-clerodane diterpenoids. Excessive hepatic gluconeogenesis is an important cause of hyperglycemia and type 2 diabetes mellitus. Herein, compounds 1, 9, 14, and 15 were found to exhibit moderate hepatic gluconeogenesis inhibitory activity in primary mouse hepatocytes, suggesting that these compounds might have potential effect on ameliorating the hyperglycaemia.

Glycogen metabolism and structure: A review

Glycogen is a glucose polymer that plays a crucial role in glucose homeostasis by functioning as a short-term energy storage reservoir in animals and bacteria. Abnormalities in its metabolism and structure can cause several problems, including diabetes, glycogen storage diseases (GSDs) and muscular disorders. Defects in the enzymes involved in glycogen synthesis or breakdown, resulting in either excessive accumulation or insufficient availability of glycogen in cells seem to account for the most common pathogenesis. This review discusses glycogen metabolism and structure, including molecular architecture, branching dynamics, and the role of associated components within the granules. The review also discusses GSD type XV and Lafora disease, illustrating the broader implications of aberrant glycogen metabolism and structure. These conditions also impart information on important regulatory mechanisms of glycogen, which hint at potential therapeutic targets. Knowledge gaps and potential future research directions are identified.

[Effects of intermittent fasting and sports performance: a narrative review]

Recently, fasted exercise has generated interest for its potential to stimulate metabolic and performance adaptations. The present study aims to analyze the effects of fasting and fasted training on performance and metabolism, acutely and chronically. The databases Medline (PubMed), Physiotherapy Evidence Database (PEDro), Cochrane, and Google Scholar were searched. In total, 767 studies were identified. Of those, 51 studies were finally included. Acutely, exercise on fasting promotes fat oxidation at low and moderate intensities, while protein catabolism is not increased. Performance is not affected in efforts lower than 1 hour. Chronically, fasting generates greater efficiency in fat metabolism and the ability to regulate blood glucose in the long term, although it has not been possible to determine whether these findings improve sports performance. More research is needed in elite athletes, with high training loads and with a periodized approach to fasting.

Biomimetic Cell Membrane Layers for the Detection of Insulin and Glucagon

The growing need for reliable and rapid insulin testing to enhance glycemic management has spurred intensive exploration of new insulin-binding bioreceptors and innovative biosensing platforms for detecting this hormone, along with glucagon, in biological samples. Here, by leveraging the native protein receptors on the HepG2 cell membrane, we construct a simple and chemical-free biomimetic molecular recognition layer for the detection of insulin and glucagon. Unlike traditional affinity sensors, which require lengthy surface modifications on the electrochemical transducers and use of two different capture antibodies to recognize each analyte, this new biomimetic sensing strategy employs a simple drop-casting of a natural cell membrane recognition layer onto the electrochemical transducer. This approach allows for the concurrent capture and detection of both insulin and glucagon. We investigate the presence of insulin and glucagon receptors on the HepG2 cell membrane and demonstrate its multiplexing bioelectronic sensing capabilities through the binding of the captured insulin and glucagon to enzyme-tagged signaling antibodies. This new molecular recognition layer offers highly sensitive simultaneous detection of insulin and glucagon under decentralized conditions, holding considerable promise for the management of diabetes and the development of diverse biomimetic diagnostic platforms.

Increased hepatic gluconeogenesis and type 2 diabetes mellitus

Abnormally increased hepatic gluconeogenesis is a significant contributor to hyperglycemia in the fasting state in patients with type 2 diabetes mellitus (T2DM) due to insulin resistance. Metformin, the most prescribed drug for the treatment of T2DM, is believed to exert its effect mainly by reducing hepatic gluconeogenesis. Here, we discuss how increased hepatic gluconeogenesis contributes to T2DM and we review newly revealed mechanisms underlying the attenuation of gluconeogenesis by metformin. In addition, we analyze the recent findings on new determinants involved in the regulation of gluconeogenesis, which might ultimately lead to the identification of novel and targeted treatment strategies for T2DM.

Incretin-based therapy: a new horizon in diabetes management

Diabetes mellitus, a metabolic syndrome characterized by hyperglycemia and insulin dysfunction, often leads to serious complications such as neuropathy, nephropathy, retinopathy, and cardiovascular disease. Incretins, gut peptide hormones released post-nutrient intake, have shown promising therapeutic effects on these complications due to their wide-ranging biological impacts on various body systems. This review focuses on the role of incretin-based therapies, particularly Glucagon-like peptide-1 (GLP-1) agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors, in managing diabetes and its complications. We also discuss the potential of novel agents like semaglutide, a recently approved oral compound, and dual/triple agonists targeting GLP-1/GIP, GLP-1/glucagon, and GLP-1/GIP/glucagon receptors, which are currently under investigation. The review aims to provide a comprehensive understanding of the beneficial impacts of natural incretins and the therapeutic potential of incretin-based therapies in diabetes management.

Grifola frondosa Polysaccharide Ameliorates Inflammation by Regulating Macrophage Polarization of Liver in Type 2 Diabetes Mellitus Rats

SCOPE

Grifola frondosa polysaccharide (GFP) has a positive effect in regulating type 2 diabetes mellitus (T2DM), but the understanding of its regulatory mechanism is still limited. Accumulating evidence suggests that hepatic inflammation is crucial in the onset and progression of insulin resistance (IR) and T2DM. However, the question of whether GFP can modulate T2DM via regulating hepatic inflammation and the underlying mechanism has not yet been reported.

METHODS AND RESULTS

High-fat diet (HFD) fed combined with streptozocin (STZ) injections rat model and Lipopolysaccharides (LPS)-treated bone marrow-derived macrophages (BMDM) model are used. The results showed that GFP intervention reduces weight loss and hyperglycemia symptoms, besides lowers FINS, HOMA-IR, IPGTT-AUC, and IPITT-AUC in T2DM rats. Meanwhile, GFP intervention reduces the secretion level of inflammatory factors and increases the secretion level of anti-inflammatory factors in the liver tissue of T2DM rats. Furthermore, GFP reduces macrophage infiltration in liver tissue, inhibits macrophage M1-type polarization, and promotes M2-type polarization.

CONCLUSIONS

These results suggest that GFP intervention could attenuate the hepatic inflammatory and insulin resistance in T2DM rats by inhibiting hepatic macrophage infiltration and modulating M1/M2 polarization. The findings provide new evidence for GFP in the early prevention and treatment of T2DM.

Opportunities for Therapeutic Modulation of O-GlcNAc

O-Linked β-N-acetylglucosamine (O-GlcNAc) is an essential, dynamic monosaccharide post-translational modification (PTM) found on serine and threonine residues of thousands of nucleocytoplasmic proteins. The installation and removal of O-GlcNAc is controlled by a single pair of enzymes, O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), respectively. Since its discovery four decades ago, O-GlcNAc has been found on diverse classes of proteins, playing important functional roles in many cellular processes. Dysregulation of O-GlcNAc homeostasis has been implicated in the pathogenesis of disease, including neurodegeneration, X-linked intellectual disability (XLID), cancer, diabetes, and immunological disorders. These foundational studies of O-GlcNAc in disease biology have motivated efforts to target O-GlcNAc therapeutically, with multiple clinical candidates under evaluation. In this review, we describe the characterization and biochemistry of OGT and OGA, cellular O-GlcNAc regulation, development of OGT and OGA inhibitors, O-GlcNAc in pathophysiology, clinical progress of O-GlcNAc modulators, and emerging opportunities for targeting O-GlcNAc. This comprehensive resource should motivate further study into O-GlcNAc function and inspire strategies for therapeutic modulation of O-GlcNAc.

Simultaneous and Rapid Detection of Glucose and Insulin: Coupling Enzymatic and Aptamer-Based Assays

Diabetes management demands precise monitoring of key biomarkers, particularly insulin (I) and glucose (G). Herein, we present a bioelectronic chip device that enables the simultaneous detection of I and G in biofluids within 2 min. This dual biosensor chip integrates aptamer-based insulin sensing with enzymatic glucose detection on a single platform, employing a four-electrode sensor chip. The insulin voltammetric sensor employs a G-quadraplex methylene-blue-modified aptamer, while the amperometric biocatalytic glucose sensor utilizes a second-generation mediator-based approach. Simultaneous reagent-less sensing of I and G has been achieved by addressing key challenges. These include combining different surface chemistries, assay formats, and detection principles at closely spaced working electrodes and the substantially different concentration levels of the I and G targets. An attractive analytical performance, with no apparent crosstalk, is demonstrated for the simultaneous detection of millimolar G concentrations and picomolar I concentrations in single microliter serum or saliva sample droplets. This dual biosensor offers rapid, cost-effective, and reliable monitoring, addressing the unmet need for integrated multiplexed diabetes biomarker detection in decentralized settings. Such integration of enzymatic and aptamer-based bioassays could greatly expand the scope of decentralized testing in healthcare beyond diabetes care.

Comparative Effects of Monascin and Monascinol Produced by Monascus pilosus SWM-008 on Pro-Inflammatory Factors and Histopathological Alterations in Liver and Kidney Tissues in a Streptozotocin-Nicotinamide-Induced Rat Model

Monascinol (Msol), an analog of monascin (MS) produced by Monascus pilosus, possesses potential anti-inflammatory properties. This study compares the effects of M. pilosus SWM-008 fermented red mold rice, which contains the functional components MS and Msol, on liver and kidney damage related to diabetic complications in rats. An animal model of liver and kidney injury was induced by an intraperitoneal injection of streptozotocin (STZ) at 65 mg/kg body weight combined with nicotinamide (NA) at 150 mg/kg body weight. Our findings indicate that Msol significantly reduces STZ-NA induced pro-inflammatory markers, including interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and cyclooxygenase-2 (COX-2) in both liver and kidney tissues. Significant improvements were noted in the histopathological assessments. Msol was more effective than MS in suppressing renal IL-1β and COX-2 expressions. In summary, the findings indicate that Msol shows potential as a novel therapeutic agent for treating liver and kidney injuries associated with diabetic complications.

Anti-Obesity Effects of Sulphated Polysaccharides Derived from Marine Macro Algae or Seaweeds: A Systematic Review and Meta-Analysis

Sulphated polysaccharides (SPs) are negatively charged compounds found in the cell wall of seaweeds or marine macro algae. These compounds exhibit a range of pharmacological activities, including anti-obesity effects. The aim of this systematic review as well as meta-analysis was to assess the potentials of seaweed-derived SPs to mitigate obesity through a systematic review and meta-analysis of animal model-based studies. A comprehensive summary of the included articles was conducted, focusing on the following obesity-related parameters: food intake, body weight gain, epididymal fat size, adipocyte size, liver weight, serum alanine transaminase (ALT) and aspartate transaminase (AST), insulin and tumour necrosis factor-α (TNF-α), and the lipid profile (total cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-c), and low-density lipoprotein cholesterol (LDL-c)). The systematic review demonstrated that seaweed-derived SPs exhibit ameliorative effects against obesity, as evidenced by reductions in food intake, body weight gain, epididymal fat and adipocyte size, liver weight, ALT and AST levels, serum insulin and TNF-α, LDL-c, total cholesterol, and triglycerides and an increase in HDL-c in obese rats administered with seaweed-derived SPs. However, the meta-analysis revealed statistically significant anti-obesity effects of seaweed-derived SPs for most, but not all the parameters tested. Further research in human subjects is necessary not only to ascertain the results of preclinical studies but also to provide conclusive evidence of the anti-obesity potential of SPs in humans.

The Interaction and Implication of Stress-Induced Hyperglycemia and Cytokine Release Following Traumatic Injury: A Structured Scoping Review

INTRODUCTION

This is a structured scoping review to assess whether there is a relationship between stress-induced hyperglycemia (SIH), cytokine interactions, and mortality in trauma patients in comparison to non-diabetic normoglycemia [NDN], diabetic normoglycemia [DN], and diabetic hyperglycemia [DH].

METHODS

We conducted a literature search of MEDLINE (PubMed) databases from 2000 to 2022 using a search strategy to identify observational studies. Initially, 2879 articles were retrieved. Of these, 2869 were excluded due to insufficient variables, and non-trauma focuses.

RESULTS

Nine studies on the interaction between SIH and proinflammatory cytokines were analyzed. SIH was associated with the highest mortality rate (21.3%), followed by DH (5.4%), DN (2.8%), and NDN (2.3%) (p < 0.001). Furthermore, SIH patients exhibited an 11.28-fold higher likelihood of mortality compared to NDN patients (95% CI [9.13-13.93]; p < 0.001) and a 4.72-fold higher likelihood compared to DH patients (OR 4.72; 95% CI [3.55-6.27]; p < 0.001).

CONCLUSIONS

SIH patients had elevated IL-6 concentrations relative to NDN, DN, and DH patients. SIH is linked to higher mortality in trauma, with greater odds than NDN. However, the robustness of this association is still being determined due to statistical and clinical variability. Uncertainties about injury severity and IL-6 level similarities between SIH and DH patients require further investigation.

Hepatic glucose production rises with the histological severity of metabolic dysfunction-associated steatohepatitis

Metabolic dysfunction-associated steatotic liver disease (MASLD) and steatohepatitis (MASH) are associated with a high prevalence of type 2 diabetes (T2D). Individuals with MASLD exhibit insulin resistance (IR) and hyperglycemia, but it is unclear whether hepatic glucose production (HGP) is increased with MASLD severity. We evaluated HGP in a cohort of histologically characterized individuals with MASL/MASH using stable isotope infusion (6,6-2H2-glucose, U-2H5-glycerol) and liver-specific genome-scale metabolic models (GEMs). Tracer-measured HGP is increased with liver fibrosis and inflammation, but not steatosis, and is associated with lipolysis and IR. The GEM-derived gluconeogenesis is elevated due to high glucogenic/energy metabolite uptakes (lactate, glycerol, and free fatty acid [FFA]), and the expression of insulin action genes (IRS1, IRS2, and AKT2) is reduced in MASH with fibrosis F2-F4, with/without T2D, suggesting these as putative mechanisms for increased fasting HGP and hyperglycemia. In conclusion, elevated HGP, lipolysis, and IR help to explain the mechanisms for the increased risk of hyperglycemia and T2D in MASH.

Effects of Saccharomyces cerevisiae on Pancreatic Alpha and Beta Cells and Metabolic Profile in Broilers

To evaluate the impact of Saccharomyces cerevisiae (SC) supplementation on pancreatic islet areas, alpha and beta cell populations, blood glucose levels, and lipid profiles in broilers, broilers were randomly assigned to two groups: a control group (T1) without SC and a treatment group (T2) supplemented with SC. Islet areas, alpha and beta cell counts, serum glucose and insulin levels, and lipid profiles were assessed. SC supplementation significantly decreased blood glucose levels compared to the control group. Additionally, HDL cholesterol levels were elevated in the SC-supplemented group. Although insulin levels remained unchanged, SC supplementation altered the correlation between pancreatic islet areas and alpha and beta cell populations, suggesting a potential influence on pancreatic islet function. Dietary supplementation with Saccharomyces cerevisiae can improve glycemic control and lipid profile in broilers. These findings highlight the potential benefits of using SC as a dietary additive in broiler production.

High-fat-diet-induced hepatic insulin resistance per se attenuates murine de novo lipogenesis

Hepatic insulin resistance (IR) is often said to be "pathway-selective" with preserved insulin stimulation of de novo lipogenesis (DNL) despite attenuated insulin signaling toward glucose metabolism. However, DNL has not been assessed in models of liver-specific IR. We studied mice with differential tissue-specific lipid-induced IR achieved by different durations of high-fat diet (HFD) feeding. Mice with isolated hepatic IR demonstrated markedly reduced DNL, with a rebound seen in mice with whole-body IR. Insr T1150A mice (protected against diacylglycerol-PKCε-induced hepatic IR) maintained normal DNL with HFD feeding. During hyperinsulinemic clamps, hepatic IR reduced DNL, but hyperglycemia augmented DNL in both resistant and sensitive animals. Regulation through SREBP1c did not consistently correlate with changes in DNL. These results demonstrate that hepatic IR is not pathway-selective, highlighting the primacy of lipogenic substrate in stimulation of DNL. Future therapeutics to reduce lipogenesis should target substrate drivers of DNL rather than targeting plasma insulin levels.

The P300-ARRDC3 axis participates in maternal subclinical hypothyroidism and is involved in abnormal hepatic insulin sensitivity in adult offspring

Numerous studies have suggested potential associations between maternal subclinical hypothyroidism (SCH) and adverse metabolic outcomes in offspring, however, the underlying mechanism remains unclear. In this study, we generated a maternal SCH mouse model by administering 50 ppm 6-propyl-2-thiouracil (PTU) in the drinking water of pregnant mice until delivery. This model was used to investigate the mechanisms influencing glucose metabolism in offspring. RNA sequencing (RNA-seq) revealed a substantial increase in ARRDC3 expression in the livers of the offspring of the SCH model mice, which may contribute to insulin resistance. Additionally, the phosphorylation levels of key proteins in the insulin signalling pathway, such as protein kinase B (Akt), glycogen synthase kinase 3 beta (GSK-3β), and Forkhead box protein O1 (FoxO1), were correspondingly reduced in the SCH offspring. Moreover, overexpression of ARRDC3 in Hepa1‒6 cells suppressed the Akt/GSK-3β/FoxO1 signalling pathway and increased the expression of glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK), which was consistent with the molecular changes observed in SCH offspring. Our results also indicated that the upregulation of ARRDC3 in SCH offspring may result from increased H3K27 acetylation of the ARRDC3 promoter region, driven by elevated expression of P300. Importantly, adequate L-T4 supplementation during pregnancy improved insulin sensitivity and reversed the molecular alterations in the insulin signalling pathway observed in SCH offspring. In conclusion, exposure to intrauterine SCH resulted in altering the P300-ARRDC3 axis in offspring and impaired insulin sensitivity by disrupting the Akt/GSK-3β/FoxO1 signalling pathway. Timely L-T4 supplementation during pregnancy is an effective strategy to prevent insulin resistance in offspring of SCH mothers. This study elucidates potential molecular mechanisms behind insulin resistance in SCH offspring and suggests novel therapeutic targets for treating metabolic disorders related to maternal SCH.

A predicted epithelial-to-mesenchymal transition-associated mRNA/miRNA axis contributes to the progression of diabetic liver disease

Despite public health measures, type 2 diabetes (T2D) is still a significant concern worldwide, given its associated complications, including hepatic alterations. The role of epithelial-to-mesenchymal transition (EMT) in liver fibrosis is well established. However, its effects on the progression of diabetic liver diseases are not well understood. Therefore, this study aims to investigate the mRNA/miRNA axes involved in this process. Bioinformatic analysis revealed new EMT-associated genes (CDH2, ITGB1, COL4A1, COL1A1, TNC, CCN2, and JUN), which showed higher expression in obese T2D and hepatocellular carcinoma (HCC) patients. In addition, six miRNAs (miR-21-5p, miR-26a-5p, miR-34a-5p, miR-106a-5p, miR-320a-3p and miR-424-5p) have been found as potential targets. Among them, miR-26a-5p and miR-424-5p were significantly downregulated in nonalcoholic steatohepatitis (NASH) and HCC (p < 0.05), being considered potential negative regulators of the EMT process. In our hepatic mesenchymal culture model, miR-26a-5p negatively regulated cadherin 2 (also known as N-cadherin, CDH2) and promoted the cadherin 1 (also known as E-cadherin, CDH1) expression. Our results reveal potential molecules involved in liver tumor development. Moreover, we observe that miR-26a-5p impairs EMT in the initial stages of diabetic liver disease by inhibiting CDH2 and could be a valuable target in this pathology.

Beyond the 9-to-5 grind: workaholism and its potential influence on human health and disease

Workaholism is often considered a conventional word in the general population to portray those individuals who continuously work and find it challenging not to work. It is usually described as a work addiction and operationalized as a compulsive need to work excessively hard. However, the concept of workaholism remains poorly understood. The first objective of this review is to define workaholism, followed by its related concepts, and how it is assessed. Notably, we distinguish workaholism from work addiction and work engagement. Next, we review the current research literature, largely from the last two decades, to suggest that workaholism contributes toward a wide range of health outcomes, ranging from sleep to stress. In particular, we focus on evidence suggesting that workaholism may be associated with differing risk factors for cardiovascular diseases and potentially other related metabolic abnormalities. Finally, we discuss potential limitations of the existing literature on workaholism, and we provide future directions for this emerging field. Specifically, we underscore the need to link workaholism with more biomarkers of metabolic diseases, such as those related to inflammation, the gut microbiome, and glucose homeostasis. In addition, we highlight the importance of establishing causality between workaholism and poor health outcomes, such as cardiovascular diseases and type 2 diabetes.

Insulin resistance during androgen deprivation therapy in men with prostate cancer

BACKGROUND

Androgen deprivation therapy (ADT) in prostate cancer (PCa) has been associated with development of insulin resistance. However, the predominant site of insulin resistance remains unclear.

METHODS

The ADT & Metabolism Study was a single-center, 24-week, prospective observational study that enrolled ADT-naive men without diabetes who were starting ADT for at least 24 weeks (ADT group, n = 42). The control group comprised men without diabetes with prior history of PCa who were in remission after prostatectomy (non-ADT group, n = 23). Prevalent diabetes mellitus was excluded in both groups using all three laboratory criteria defined in the American Diabetes Association guidelines. All participants were eugonadal at enrollment. The primary outcome was to elucidate the predominant site of insulin resistance (liver or skeletal muscle). Secondary outcomes included assessments of body composition, and hepatic and intramyocellular fat. Outcomes were assessed at baseline, 12, and 24 weeks.

RESULTS

At 24 weeks, there was no change in hepatic (1.2; 95% confidence interval [CI], -2.10 to 4.43; p = .47) or skeletal muscle (-3.2; 95% CI, -7.07 to 0.66; p = .10) insulin resistance in the ADT group. No increase in hepatic or intramyocellular fat deposition or worsening of glucose was seen. These changes were mirrored by those observed in the non-ADT group. Men undergoing ADT gained 3.7 kg of fat mass.

CONCLUSIONS

In men with PCa and no diabetes, 24 weeks of ADT did not change insulin resistance despite adverse body composition changes. These findings should be reassuring for treating physicians and for patients who are being considered for short-term ADT.

Optimized methods to image hepatic lipid droplets in zebrafish larvae

The optical transparency of zebrafish larvae enables visualization of subcellular structures in intact organs, and these vertebrates are widely used to study lipid biology and liver disease. Lipid droplet (LD) presence is a prevalent feature of healthy cells, but, under conditions such as nutrient excess, toxicant exposure or metabolic imbalance, LD accumulation in hepatocytes can be a harbinger of more severe forms of liver disease. We undertook a comprehensive analysis of approaches useful to investigate LD distribution and dynamics in physiological and pathological conditions in the liver of zebrafish larvae. This comparative analysis of the lipid dyes Oil Red O, Nile Red, LipidTox and LipidSpot, as well as transgenic LD reporters that rely on EGFP fusions of the LD-decorating protein perilipin 2 (PLIN2), demonstrates the strengths and limitations of each approach. These protocols are amenable to detection methods ranging from low-resolution stereomicroscopy to confocal imaging, which enables measurements of hepatic LD size, number and dynamics at cellular resolution in live and fixed animals. This resource will benefit investigators studying LD biology in zebrafish disease models.

Integrated metabolomic and transcriptomic analysis reveals the effects and mechanisms of Jinqi Jiangtang tablets on type 2 diabetes

BACKGROUND

Type 2 diabetes (T2DM) is one of the major metabolic diseases and poses a serious challenge to human life and global economic development. Jinqi Jiangtang Tablets (JQJT) is effective in ameliorating the effects of T2DM, but the mechanism of JQJT is unclear.

PURPOSE

This study integrated metabolomics and transcriptomics to reveal the mechanism by which JQJT improves T2DM.

METHODS

The T2DM mouse model was established, and the effects of JQJT on improving T2DM were evaluated by determining the levels of blood lipids, fasting blood glucose (FBG), insulin metabolism and hepatic lipid accumulation in mice after JQJT administration for 8 weeks. Serum metabolites were detected using ultra-performance liquid chromatography/quadrupole time-of-flight-tandem mass spectrometry (UPLC-Q-TOF-MS) technology, and mouse liver differential genes were detected using transcriptomic technology. Correlation analysis was used to extract metabolites and RNA with correlations, and potential pathways were enriched and constructed using the common pathway analysis function of MetaboAnalyst 5.0. Finally, the expression of key target proteins and genes was verified by Western blot (WB) and Polymerase Chain Reaction (PCR) to further elucidate the mechanism by which JQJT improves T2DM.

RESULTS

JQJT reduced FBG and lipid levels, improved insulin resistance (IR) and hepatic lipoatrophy in mice. A total of 35 differentially abundant metabolites were identified by metabolomics, and 328 differential genes were detected by transcriptomics. The integrated metabolomics and transcriptomics results suggested that JQJT may ameliorate T2DM mainly by regulating glucose and lipid metabolic pathways. WB and PCR results showed that JQJT regulates the insulin signaling pathway, involved in fatty acid metabolism, glycogen synthesis and catabolism.

CONCLUSIONS

JQJT improved IR in T2DM mice by regulating the insulin signaling pathway, improving glycogen synthesis and glycolysis, and increasing hepatic triglyceride and fatty acid metabolism.

The potential auxiliary effects of Sargassum fusiform polysaccharides on sitagliptin in the treatment of diabetes mellitus

This work aimed to evaluate the potential positive effects of Sargassum fusiform polysaccharides (SFP) as add-on adjuncts to sitagliptin (SIT) in treating diabetes in rats. The results showed that both SIT and SIT co-administrated with SFP (SIT+SFP) could improve hyperglycemia, glucose tolerance, insulin resistance and hyperlipidemia, and SIT+SFP exhibited better effects in alleviating the levels of blood glucose, glucose tolerance, insulin resistance index, cholesterol, and low-density lipoprotein cholesterol compared to SIT administration. Intestinal flora analysis showed that SIT+SFP treatment significantly restored the beneficial composition of gut flora as compared with SIT administration, such as the increase of Lactobacillus, Romboutsia, Blautia, Bifidobacterium, Bacteroides, Ruminococcaceae_UCG_014 and Ruminococcus_1, and the decrease of Helicobacter, Escherichia-Shigella and Pseudomonas. The fecal metabolite analysis demonstrated that the fecal bile acid and short-chain fatty acid levels in the SIT+SFP group significantly increased compared to SIT treatment. Additionally, mRNA expression results confirmed that the hypoglycemic effects of SIT+SFP were better than those of SIT, which might be attributed to the regulation of blood glucose absorption, inhibition of gluconeogenesis and regulation of cholesterol metabolism. These results suggested that SFP could be used as an auxiliary substance for SIT in treating diabetes mellitus.

VEGFB ameliorates insulin resistance in NAFLD via the PI3K/AKT signal pathway

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is one of the most universal liver diseases with complicated pathogenesis throughout the world. Insulin resistance is a leading risk factor that contributes to the development of NAFLD. Vascular endothelial growth factor B (VEGFB) was described by researchers as contributing to regulating lipid metabolic disorders. Here, we investigated VEGFB as a main target to regulate insulin resistance and metabolic syndrome.

METHODS

In this study, bioinformatics, transcriptomics, morphological experiments, and molecular biology were used to explore the role of VEGFB in regulating insulin resistance in NAFLD and its molecular mechanism based on human samples, animal models, and cell models. RNA-seq was performed to analyze the signal pathways associated with VEGFB and NAFLD; Palmitic acid and High-fat diet were used to induce insulin-resistant HepG2 cells model and NAFLD animal model. Intracellular glucolipid contents, glucose uptake, hepatic and serum glucose and lipid levels were examined by Microassay and Elisa. Hematoxylin-eosin staining, Oil Red O staining, and Periodic acid-schiff staining were used to analyze the hepatic steatosis, lipid droplet, and glycogen content in the liver. Western blot and quantitative real-time fluorescent PCR were used to verify the expression levels of the VEGFB and insulin resistance-related signals PI3K/AKT pathway.

RESULTS

We observed that VEGFB is genetically associated with NAFLD and the PI3K/AKT signal pathway. After VEGFB knockout, glucolipids levels were increased, and glucose uptake ability was decreased in insulin-resistant HepG2 cells. Meanwhile, body weight, blood glucose, blood lipids, and hepatic glucose of NAFLD mice were increased, and hepatic glycogen, glucose tolerance, and insulin sensitivity were decreased. Moreover, VEGFB overexpression reduced glucolipids and insulin resistance levels in HepG2 cells. Specifically, VEGFB/VEGFR1 activates the PI3K/AKT signals by activating p-IRS1Ser307 expression, inhibiting p-FOXO1pS256 and p-GSK3Ser9 expressions to reduce gluconeogenesis and glycogen synthesis in the liver. Moreover, VEGFB could also enhance the expression level of GLUT2 to accelerate glucose transport and reduce blood glucose levels, maintaining glucose homeostasis.

CONCLUSIONS

Our studies suggest that VEGFB could present a novel strategy for treating NAFLD as a positive factor.

A peptide derived from the amino terminus of leptin improves glucose metabolism and energy homeostasis in myotubes and db/db mice

Leptin is an adipokine, which plays key roles in regulation of glucose metabolism and energy homeostasis. Therefore, identification of a short peptide from leptin which improves glucose-metabolism and energy-homeostasis could be of significant therapeutic importance. Mutational studies demonstrated that N-terminal of human leptin hormone is crucial for activation of leptin-receptor while its C-terminal seems to have lesser effects in it. Thus, for finding a metabolically active peptide and complimenting the mutational studies on leptin, we have identified a 17-mer (leptin-1) and a 16-mer (leptin-2) segment from its N-terminal and C-terminal, respectively. Consistent with the mutational studies, leptin-1 improved glucose-metabolism by increasing glucose-uptake, GLUT4 expression and its translocation to the plasma membrane in L6-myotubes, while leptin-2 was mostly inactive. Leptin-1-induced glucose-uptake is mediated through activation of AMPK, PI3K, and AKT proteins since inhibitors of these proteins inhibited the event. Leptin-1 activated leptin-receptor immediate downstream target protein, JAK2 reflecting its possible interaction with leptin-receptor while leptin-2 was less active. Furthermore, leptin-1 increased mitochondrial-biogenesis and ATP-production, and increased expression of PGC1α, NRF1, and Tfam proteins, that are important regulators of mitochondrial biogenesis. The results suggested that leptin-1 improved energy-homeostasis in L6-myotubes, whereas, leptin-2 showed much lesser effects. In diabetic, db/db mice, leptin-1 significantly decreased blood glucose level and improved glucose-tolerance. Leptin-1 also increased serum adiponectin and decreased serum TNF-α and IL-6 level signifying the improvement in insulin-sensitivity and decrease in insulin-resistance, respectively in db/db mice. Overall, the results show the identification of a short peptide from the N-terminal of human leptin hormone which significantly improves glucose-metabolism and energy-homeostasis.

The association between stress hyperglycemia ratio and nonalcoholic fatty liver disease among U.S. adults: A population-based study

BACKGROUND AND AIM

The stress hyperglycemia ratio (SHR) offers a more nuanced understanding of glucose metabolism by factoring in the background glycemia through the component of Hemoglobin A1c. The association of SHR with cardiovascular and cerebrovascular diseases has been established, but the relationship between SHR and the risk of nonalcoholic fatty liver disease (NAFLD) remains unexplored. This study aimed to elucidate the relationship between the two among U.S. adults with diabetes or prediabetes.

METHODS AND RESULTS

A total of 1409 participants diagnosed with diabetes or prediabetes from the National Health and Nutrition Examination Survey (NHANES) 2017-2020 were included in this study. Multiple logistic regression models (ranging from unadjusted to fully adjusted), restricted cubic splines, and subgroup analyses were employed to determine the relationship between SHR and NAFLD risk and to assess the stability of this relationship across different populations. The average age of all participants was 54.65 years, with males accounting for 47.91 %, and the prevalence of NAFLD being 68.77 %. A fully adjusted logistic regression model indicated a positive association between SHR levels and the risk of NAFLD. Specifically, for each one standard deviation increase in SHR, the risk of NAFLD increased by 20 % (OR, 1.2; 95 % CI, 1.0-1.4). Both the trend test and the restricted cubic splines suggested a linear relationship between the two variables (p for trend <0.05, p for nonlinear = 0.390). Subgroup analysis demonstrated that this positive association remained consistent across most subgroups.

CONCLUSIONS

SHR was identified as a valuable index for predicting the risk of NAFLD among U.S. adults with diabetes or prediabetes.

Effects of Zeaxanthin on the Insulin Resistance and Gut Microbiota of High-Fat-Diet-Induced Obese Mice

Obesity-induced insulin resistance (IR) can precipitate metabolic disorders such as diabetes. Zeaxanthin, a crucial member of the carotenoid family, has been found to mitigate the damage caused by obesity. However, reports on the effects of zeaxanthin on obesity-induced IR are lacking. Our objective was to examine the metabolic regulatory impacts of zeaxanthin on mice subjected to a high-fat diet (HFD) that triggered IR and to explore their influence on gut microbiota regulation. This study constructed a mouse model of metabolic dysfunction caused by lipid-rich nutritional patterns to investigate physiological and biochemical indices, liver pathway expression, and the intestinal microbiota. The mechanisms by which zeaxanthin improved both IR and glucose metabolic disorders were elucidated. The results demonstrate that zeaxanthin effectively suppressed obesity. The fasting blood glucose, area under curve of oral glucose tolerance test and insulin tolerance test, and homeostatic model assessment-insulin resistance (HOMA-IR) indices in the HFDZEA group decreased by 14.9%, 25.2%, 28.9%, and 29.8%. Additionally, zeaxanthin improved the lipid metabolism and alleviated damage to the liver and pancreas while also activating the PI3K/Akt pathway, regulating hepatic gluconeogenesis and the glycogen metabolism. The number of OTUs in the HFDZEA group increased by 29.04%. Zeaxanthin improved the structure and profile of the gastrointestinal microbiome and enhanced its diversity, increasing probiotics abundance, decreasing pathogen abundance, and thereby ameliorating the dysbiosis of enteric microbial communities in rodents with obesity resulting from excessive fat consumption. The outcomes of our analysis provide a rational basis for advancing zeaxanthin-based nutritional products.

Glucose metabolism in the perfused liver did not improve with resistance training in male Swiss mice under caloric restriction

CONTEXT

Energy homeostasis is a primary factor for the survival of mammals. Many tissues and organs, among which is the liver, keep this homeostasis in varied circumstances, including caloric restriction (CR) and physical activity.

OBJECTIVE

This study investigated glucose metabolism using the following groups of eight-week-old male Swiss mice: CS, sedentary and fed freely; RS, sedentary and RT, trained, both under 30% CR (n = 20-23 per group).

RESULTS

Organs and fat depots of groups RS and RT were similar to CS, although body weight was lower. CR did not impair training performance nor affected systemic or hepatic glucose metabolism. Training combined with CR (group RT) improved in vivo glucose tolerance and did not affect liver gluconeogenesis.

CONCLUSIONS

The mice tolerated the prolonged moderate CR without impairment of their well-being, glucose homeostasis, and resistance training performance. But the higher liver gluconeogenic efficiency previously demonstrated using this training protocol in mice was not evidenced under CR.

BCKDH kinase promotes hepatic gluconeogenesis independent of BCKDHA

Elevated circulating branched-chain amino acids (BCAAs) are tightly linked to an increased risk in the development of type 2 diabetes mellitus. The rate limiting enzyme of BCAA catabolism branched-chain α-ketoacid dehydrogenase (BCKDH) is phosphorylated at E1α subunit (BCKDHA) by its kinase (BCKDK) and inactivated. Here, the liver-specific BCKDK or BCKDHA knockout mice displayed normal glucose tolerance and insulin sensitivity. However, knockout of BCKDK in the liver inhibited hepatic glucose production as well as the expression of key gluconeogenic enzymes. No abnormal gluconeogenesis was found in mice lacking hepatic BCKDHA. Consistent with the vivo results, BT2-mediated inhibition or genetic knockdown of BCKDK decreased hepatic glucose production and gluconeogenic gene expressions in primary mouse hepatocytes while BCKDK overexpression exhibited an opposite effect. Whereas, gluconeogenic gene expressions were not altered in BCKDHA-silenced hepatocytes. Mechanistically, BT2 treatment attenuated the interaction of cAMP response element binding protein (CREB) with CREB-binding protein and promoted FOXO1 protein degradation by increasing its ubiquitination. Our findings suggest that BCKDK regulates hepatic gluconeogenesis through CREB and FOXO1 signalings, independent of BCKDHA-mediated BCAA catabolism.

Identification and molecular mechanism of novel hypoglycemic peptide in ripened pu-erh tea: Molecular docking, dynamic simulation, and cell experiments

Ripened pu-erh tea is known to have beneficial hypoglycemic properties. However, it remains unclear whether the bioactive peptides produced during fermentation are also related to hypoglycemic potential. This study aimed to identify hypoglycemic peptides in ripened pu-erh tea and to elucidate their bioactive mechanisms using physicochemical property prediction, molecular docking, molecular dynamics simulations, and cell experiments. Thirteen peptides were identified by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). Among them, AADTDYRFS (AS-9) and AGDGTPYVR (AR-9) exhibited high α-glucosidase inhibitory activity, with half-maximal inhibitory concentration (IC50) values of 0.820 and 3.942 mg/mL, respectively. Molecular docking and dynamics simulations revealed that hydrogen bonding, hydrophobic interactions, and van der Waals forces assist peptides AS-9 and AR-9 in forming stable and tight complexes with α-glucosidase. An insulin-resistance (IR)-HepG2 cell model was established. AS-9 was non-toxic to IR-HepG2 cells and significantly increased the glucose consumption capacity, hexokinase, and pyruvate kinase activities of IR-HepG2 cells (p < 0.05). AS-9 alleviated glucose metabolism disorders and ameliorated IR by activating the IRS-1/PI3K/Akt signaling pathway and increasing the expression levels of MDM2, IRS-1, Akt, PI3K, GLUT4, and GSK3β genes. In addition, no hemolysis of mice red blood cells red blood cells occurred at concentrations below 1 mg/mL. This work first explored hypoglycemic peptides in ripened pu-erh tea, providing novel insights for enhancing its functional value.

Complex dichotomous links of nonalcoholic fatty liver disease and inflammatory bowel disease: exploring risks, mechanisms, and management modalities

Nonalcoholic fatty liver disease (NAFLD) has been shown to be linked to inflammatory bowel disease (IBD) due to established risk factors such as obesity, age, and type 2 diabetes in numerous studies. However, alternative research suggests that factors related to IBD, such as disease activity, duration, and drug-induced toxicity, can contribute to NAFLD. Recent research findings suggest IBD relapses are correlated with dysbiosis, mucosal damage, and an increase in cytokines. In contrast, remission periods are characterized by reduced metabolic risk factors. There is a dichotomy evident in the associations between NAFLD and IBD during relapses and remissions. This warrants a nuanced understanding of the diverse influences on disease manifestation and progression. It is possible to provide a holistic approach to care for patients with IBD by emphasizing the interdependence between metabolic and inflammatory disorders.

LRP1 facilitates hepatic glycogenesis by improving the insulin signaling pathway in HFD-fed mice

BACKGROUND

LDL receptor-related protein-1 (LRP1) is a cell-surface receptor that functions in diverse physiological pathways. We previously demonstrated that hepatocyte-specific LRP1 deficiency (hLRP1KO) promotes diet-induced insulin resistance and increases hepatic gluconeogenesis in mice. However, it remains unclear whether LRP1 regulates hepatic glycogenesis.

METHODS

Insulin signaling, glycogenic gene expression, and glycogen content were assessed in mice and HepG2 cells. The pcDNA 3.1 plasmid and adeno-associated virus serotype 8 vector (AAV8) were used to overexpress the truncated β-chain (β∆) of LRP1 both in vitro and in vivo.

RESULTS

On a normal chow diet, hLRP1KO mice exhibited impaired insulin signaling and decreased glycogen content. Moreover, LRP1 expression in HepG2 cells was significantly repressed by palmitate in a dose- and time-dependent manner. Both LRP1 knockdown and palmitate treatment led to reduced phosphorylation of Akt and GSK3β, increased levels of phosphorylated glycogen synthase (GYS), and diminished glycogen synthesis in insulin-stimulated HepG2 cells, which was restored by exogenous expression of the β∆-chain. By contrast, AAV8-mediated hepatic β∆-chain overexpression significantly improved the insulin signaling pathway, thus activating glycogenesis and enhancing glycogen storage in the livers of high-fat diet (HFD)-fed mice.

CONCLUSION

Our data revealed that LRP1, especially its β-chain, facilitates hepatic glycogenesis by improving the insulin signaling pathway, suggesting a new therapeutic strategy for hepatic insulin resistance-related diseases.

PGE2 synthesis and signaling in the liver physiology and pathophysiology: An update

The liver plays a central role in systemic metabolism and drug degradation. However, it is highly susceptible to damage due to various factors, including metabolic imbalances, excessive alcohol consumption, viral infections, and drug influences. These factors often result in conditions such as fatty liver, hepatitis, and acute or chronic liver injury. Failure to address these injuries could promptly lead to the development of liver cirrhosis and potentially hepatocellular carcinoma (HCC). Prostaglandin E2 (PGE2) is a metabolite of arachidonic acid that belongs to the class of polyunsaturated fatty acids (PUFA) and is synthesized via the cyclooxygenase (COX) pathway. By binding to its G protein coupled receptors (i.e., EP1, EP2, EP3 and EP4), PGE2 has a wide range of physiological and pathophysiology effects, including pain, inflammation, fever, cardiovascular homeostasis, etc. Recently, emerging studies showed that PGE2 plays an indispensable role in liver health and disease. This review focus on the research progress of the role of PGE2 synthase and its receptors in liver physiological and pathophysiological processes and discuss the possibility of developing liver protective drugs targeting the COXs/PGESs/PGE2/EPs axis.

The Important Role of Aquaglyceroporin 7 in Health and Disease

Aquaporins (AQPs) are highly conserved small transmembrane proteins that facilitate the transport of water and small solutes across cell membranes. Aquaglyceroporin 7 (AQP7), a significant member of the AQP family, is widely distributed throughout the body. For years, AQP7 was predominantly recognized for its role as a small-molecule transporter, facilitating the passage of small molecular substances. However, growing studies have revealed that AQP7 is also involved in the regulation of lipid synthesis, gluconeogenesis, and energy homeostasis, and it is intimately linked to a variety of diseases, such as obesity, type 2 diabetes mellitus, cardiovascular diseases, cancer, and inflammatory bowel disease. This article presents a comprehensive overview of the structure of AQP7, its regulatory mechanisms, its vital roles in both healthy and diseased states, and potential therapeutic advancements. We hope that these studies will serve as a valuable reference for the development of future treatments and diagnostic protocols targeting AQP7.

Morning Engagement of Hepatic Insulin Receptors Improves Afternoon Hepatic Glucose Disposal and Storage

Glucose tolerance improves significantly upon consuming a second, identical meal later in the day (second meal phenomenon). We previously established that morning hyperinsulinemia primes the liver for increased afternoon hepatic glucose uptake (HGU). Although the route of insulin delivery is an important determinant of the mechanisms by which insulin regulates liver glucose metabolism (direct hepatic vs indirect insulin action), it is not known if insulin's delivery route affects the second meal response. To determine whether morning peripheral insulin delivery (as occurs clinically (subcutaneous)) can enhance afternoon HGU, conscious dogs were treated in the morning with insulin delivered via the portal vein, or peripherally (leg vein), while glucose was infused to maintain euglycemia. Consequently, arterial insulin levels increased similarly in both groups, but relative hepatic insulin deficiency occurred when insulin was delivered peripherally. In the afternoon, all animals were challenged with the same hyperinsulinemic-hyperglycemic clamp to simulate identical postprandial-like conditions. The substantial enhancement of HGU in the afternoon caused by morning portal vein insulin delivery was lost when insulin was delivered peripherally. This indicates that morning insulin does not cause the second meal phenomenon via its indirect actions on the liver, but rather through direct activation of hepatic insulin signaling.

Circadian Regulatory Networks of Glucose Homeostasis and Its Disruption as a Potential Cause of Undernutrition

The circadian clock system, an evolutionarily conserved mechanism, orchestrates diurnal rhythms in biological activities such as behavior and metabolism, aligning them with the earth's 24-hour light/dark cycle. This synchronization enables organisms to anticipate and adapt to predictable environmental changes, including nutrient availability. However, modern lifestyles characterized by irregular eating and sleeping habits disrupt this synchrony, leading to metabolic disorders such as obesity and metabolic syndrome, evidenced by higher obesity rates among shift workers. Conversely, circadian disturbances are also associated with reduced nutrient absorption and an increased risk of malnutrition in populations such as the critically ill or the elderly. The precise mechanisms of these disturbances in leading to either overnutrition or undernutrition is complex and not yet fully understood. Glucose, a crucial energy source, is closely linked to obesity when consumed excessively and to weight loss when intake is reduced, which suggests that circadian regulation of glucose metabolism is a key factor connecting circadian disturbances with nutritional outcomes. In this review, we describe how the biological clock in various tissues regulates glucose metabolism, with a primary focus on studies utilizing animal models. Additionally, we highlight current clinical evidence supporting the association between circadian disturbance and glucose metabolism, arguing that such disruption could predominantly contribute to undernutrition due to impaired efficient utilization of nutrients.

The fate of pyruvate dictates cell growth by modulating cellular redox potential

Pyruvate occupies a central node in carbohydrate metabolism such that how it is produced and consumed can optimize a cell for energy production or biosynthetic capacity. This has been primarily studied in proliferating cells, but observations from the post-mitotic Drosophila fat body led us to hypothesize that pyruvate fate might dictate the rapid cell growth observed in this organ during development. Indeed, we demonstrate that augmented mitochondrial pyruvate import prevented cell growth in fat body cells in vivo as well as in cultured mammalian hepatocytes and human hepatocyte-derived cells in vitro. This effect on cell size was caused by an increase in the NADH/NAD+ ratio, which rewired metabolism toward gluconeogenesis and suppressed the biomass-supporting glycolytic pathway. Amino acid synthesis was decreased, and the resulting loss of protein synthesis prevented cell growth. Surprisingly, this all occurred in the face of activated pro-growth signaling pathways, including mTORC1, Myc, and PI3K/Akt. These observations highlight the evolutionarily conserved role of pyruvate metabolism in setting the balance between energy extraction and biomass production in specialized post-mitotic cells.

Foxo1 is an iron-responsive transcriptional factor regulating systemic iron homeostasis

ABSTRACT

The liver plays a crucial role in maintaining systemic iron homeostasis by secreting hepcidin, which is essential for coordinating iron levels in the body. Imbalances in iron homeostasis are associated with various clinical disorders related to iron deficiency or iron overload. Despite the clinical significance, the mechanisms underlying how hepatocytes sense extracellular iron levels to regulate hepcidin synthesis and iron storage are not fully understood. In this study, we identified Foxo1, a well-known regulator of macronutrient metabolism, which translocates to the nucleus of hepatocytes in response to high-iron feeding, holo-transferrin, and bone morphogenetic protein 6 (BMP6) treatment. Furthermore, Foxo1 plays a crucial role in mediating hepcidin induction in response to both iron and BMP signals by directly interacting with evolutionally conserved Foxo binding sites within the hepcidin promoter region. These binding sites were found to colocalize with Smad-binding sites. To investigate the physiological relevance of Foxo1 in iron metabolism, we generated mice with hepatocyte-specific deletion of Foxo1. These mice exhibited reduced hepatic hepcidin expression and serum hepcidin levels, accompanied by elevated serum iron and liver nonheme iron concentrations. Moreover, high-iron diet further exacerbated these abnormalities in iron metabolism in mice lacking hepatic Foxo1. Conversely, hepatocyte-specific Foxo1 overexpression increased hepatic hepcidin expression and serum hepcidin levels, thereby ameliorating iron overload in a murine model of hereditary hemochromatosis (Hfe-/- mice). In summary, our study identifies Foxo1 as a critical regulator of hepcidin and systemic iron homeostasis. Targeting Foxo1 may offer therapeutic opportunities for managing conditions associated with aberrant iron metabolism.

Licochalcone D from Glycyrrhiza uralensis Improves High-Glucose-Induced Insulin Resistance in Hepatocytes

This study investigated the therapeutic potential of licochalcone D (LicoD), which is derived from Glycyrrhiza uralensis, for improving glucose metabolism in AML12 hepatocytes with high-glucose-induced insulin resistance (IR). Ultra-high-performance liquid chromatography-mass spectrometry revealed that the LicoD content of G. uralensis was 8.61 µg/100 mg in the ethanol extract (GUE) and 0.85 µg/100 mg in the hot water extract. GUE and LicoD enhanced glucose consumption and uptake, as well as Glut2 mRNA expression, in high-glucose-induced IR AML12 cells. These effects were associated with the activation of the insulin receptor substrate/phosphatidylinositol-3 kinase signaling pathway, increased protein kinase B α phosphorylation, and suppression of gluconeogenesis-related genes, such as Pepck and G6pase. Furthermore, GUE and LicoD promoted glycogen synthesis by downregulating glycogen phosphorylase. Furthermore, LicoD and GUE mitigated the downregulated expression of mitochondrial oxidative phosphorylation proteins in IR hepatocytes by activating the PPARα/PGC1α pathway and increasing the mitochondrial DNA content. These findings demonstrate the potential of LicoD and GUE as therapeutic options for alleviating IR-induced metabolic disorders by improving glucose metabolism and mitochondrial function.

Study on the signaling pathways involved in the anti-hyperglycemic effect of raspberry ketone on zebrafish using integrative transcriptome and metabolome analyses

Hyperglycemia leads to increased oxidative stress in mitochondria, an abnormal activation of intracellular inflammatory signals, and mediate multiple dysfunctions. Raspberry ketone (RK) is an aromatic phenolic compound found in many plants and could contribute to weight loss, restore impaired glucose tolerance, and has antioxidant properties. In our investigation, RK could greatly prevent islet, brain and other tissue damage caused by hyperglycemia in a zebrafish model with streptozotocin (STZ)-induced hyperglycemia. Body weight, insulin level, and food intake indexes were also restored by RK. Using transcriptome profiling, we found that RK administration could significantly attenuate STZ-induced insulin synthesis and pancreatic secretion as well as alter protein and carbohydrate metabolism. Metabolomics analysis results showed that RK could also prevent STZ-induced metabolic disorders, such as adenosine and sphingolipid metabolism. Integrative analysis of metabolome and transcriptome data and qRT-PCR validation of key metabolic regulatory genes (glut1, glut2, ctrb1, ccka, gck, pklr) confirmed that the purine pathway was the most enriched metabolic pathway, in which both metabolite accumulation and gene expression levels showed consistent change patterns upon RK treatment. Our study provides a new perspective for understanding the hypoglycemic mechanism of RK and may be helpful for investigating the modes of action of hypoglycemic drugs using the zebrafish hyperglycemia model.

DNA 5mC and RNA m6A Collaborate to Upregulate Phosphoenolpyruvate Carboxykinase 2 for Kupffer Cell Activation

Both DNA 5-methylcytosine (5mC) and RNA N6-methyladenosine (m6A) modifications are reported to participate in cellular stress responses including inflammation. Phosphoenolpyruvate carboxykinase 2 (PCK2) is upregulated in Kupffer cells (KCs) to facilitate the proinflammatory phosphorylation signaling cascades upon LPS stimulation, yet the role of 5mC and m6A in PCK2 upregulation remain elusive. Here, we report that the significantly augmented PCK2 mRNA and protein levels are associated with global 5mC demethylation coupled with m6A hypermethylation in LPS-activated KCs. The suppression of 5mC demethylation or m6A hypermethylation significantly alleviates the upregulation of PCK2 and proinflammatory cytokines in LPS-challenged KCs. Further reciprocal tests indicate 5mC demethylation is upstream of m6A hypermethylation. Specifically, CpG islands in the promoters of PCK2 and RNA methyltransferase (METTL3 and METTL14) genes are demethylated, while the 3'UTR of PCK2 mRNA is m6A hypermethylated, in LPS-stimulated KCs. These modifications contribute to the transactivation of the PCK2 gene as well as increased PCK2 mRNA stability and protein production via a m6A-mediated mechanism with IGF2BP1 as the reader protein. These results indicate that DNA 5mC and RNA m6A collaborate to upregulate PCK2 expression, respectively, at the transcriptional and post-transcriptional levels during KC activation.

Strong associations between fasting lipids and glucose concentrations and ALT levels strengthened with increasing ALT quantiles

BACKGROUND

A persistent redox state and excessive reactive species involved in carbohydrate and lipid metabolism lead to oxidative damage in the liver, however, how fasting plasma concentrations of lipids and glucose are associated with fasting blood levels of alanine transaminase (ALT) and aspartate transaminase (AST) remains to be evaluated in large-scale population.

METHODS

A cross-sectional study with 182,971 residents aged 18 to 92 years; multidimensional stratified analyses including quantile linear regression analysis and sex stratification were adopted to improve the quality of the evidence.

RESULTS

The associations between the concentrations of non-HDL-C and triglyceride and ALT levels were positive, stronger in males in each quantile of ALT levels and the coefficients expanded with increasing ALT levels at slopes of 3.610 and 5.678 in males and 2.977 and 5.165 in females, respectively. The associations between the HDL-C concentrations and ALT levels were negative, also stronger in males in each quantile and the coefficients expanded with increasing ALT levels at slopes of -7.839 in females and - 5.797 in males. The associations between glucose concentrations and ALT levels were positive, but stronger in females in each quantile and the coefficients expanded with increasing ALT levels at slopes of 1.736 in males and 2.177 in females, respectively. Similar pattern consist of relatively weaker coefficients and slops were observed between concentrations of non-HDL-C, triglyceride and glucose and AST levels. The associations between albumin concentration and concentrations of blood lipids and glucose were relatively steady across all quantiles.

CONCLUSIONS

The dose dependent effect between blood concentrations of lipids and glucose and liver function changes suggests that excessive carbohydrate and lipid metabolism may cause subclinical liver damage. Long term sustained primary and secondary inflammatory factors produced in the liver might be transmitted to adjacent organs, such as the heart, kidneys, and lungs, to cause and/or exacerbate pathological changes in these visceral organs.