An Overview of Murine High Fat Diet as a Model for Type 2 Diabetes Mellitus

Pharmacodynamic and pharmacokinetic profiles of a novel GLP-1 receptor biased agonist-SAL0112

BACKGROUND AND PURPOSE

GLP-1 receptor agonists are clinically utilized for type 2 diabetes and obesity. In vitro and in vivo preclinical studies were performed to assess the druggability of a novel small molecule GLP-1 receptor biased agonist SAL0112.

EXPERIMENTAL APPROACH

The HTRF assay, FLIPR assay, TR-FRET assay, and PathHunter assay were utilized for in vitro studies. Liver transporter tests were conducted using the HEK293-OATP1B1 and HEK293-OATP1B3 cell lines. In vitro stability assessments of various species and in vivo PK studies in rodents were performed. A model of type 2 diabetes and obesity induced by a high-energy diet in transgenic C57BL/6 mice expressing the human GLP-1 receptor gene was conducted.

PRINCIPAL RESULTS

SAL0112 demonstrated high potency and selectivity in activating the Gαs pathway of the GLP-1 receptor, with no observed desensitization. SAL0112 demonstrated greater stability in human and rat liver microsomes compared to Danuglipron. In vivo PK studies revealed higher absorption of SAL0112 in rats. SAL0112 displayed a significantly lower potential for DDI on liver transporters compared to Danuglipron. SAL0112 led to significant reductions in body weight (P<0.001), blood glucose levels in OGTT (P<0.001), HbA1c (P<0.05) and improved insulin resistance (P<0.01). Notably, it increased peripheral adipocyte density and resolved hepatic steatosis. The efficacy of SAL0112 was found to be comparable to that of Danuglipron and Liraglutide.

CONCLUSION

SAL0112 demonstrated potent and selective GLP-1 receptor biased agonism, effectively alleviating signs of type 2 diabetes in a mouse model. These promising findings pave the way for the advancement of SAL0112 into clinical trials.

Walnut oil: a promising nutraceutical in reducing oxidative stress and improving cholinergic activity in an in vitro Alzheimer's disease model

Improving the quality of life in elderly patients and finding new treatment options for neurological diseases such as Alzheimer's has become one of the priorities in the scientific world. In recent years, the beneficial effects and therapeutic properties of natural foods on neurological health have become a very remarkable issue. Walnut oil (WO) is a promising nutraceutical, with many phytochemicals and polyunsaturated fatty acids and is thought to be promising in the treatment of many neurological diseases and cognitive deficits, such as Alzheimer's disease (AD). Polyphenolic compounds found in WO enhance intraneuronal signaling and neurogenesis and improve the sequestration of insoluble toxic protein aggregates. The objective of this study was to investigate the potential protective and therapeutic effects of WO in a model of AD induced by retinoic acid (RA) and brain-derived neurotrophic factor (BDNF). In order to achieve this, the experimental groups were formed as follows: Control group, WO group, Alzheimer's disease (AD) group, AD + WO applied group (AD + WO). WO supplementation almost significantly reduced oxidative stress in the ad model, providing 2-fold protection against protein oxidation. Additionally, WO showed a significant reduction in tau protein levels (2-fold), increased acetylcholine (ACh) levels (12%), and decreased acetylcholine esterase (AChE) activity (~50%). Since it has been known for centuries that WO does show any adverse effects on human health and has neuroprotective properties, it may be used in the treatment of AD as an additional nutraceutical to drug treatments.

High-fat diet-induced increase in glucocorticoids contributes to adipogenesis in obese mice

BACKGROUND

This study was designed to examine how glucocorticoids (GCs) induced by a long-term ingestion of high-fat diet (HFD) mediate the HFD-induced adipose expansion and obesity.

MATERIAL AND METHODS

To address this goal, we used a unique L/L mouse model that fails to induce its corticosterone (CORT) level, a major type of GCs in rodents, after prolonged exposure to an HFD.

RESULTS

We found that, after receiving a 12-week HFD feeding, the L/L mice show less weight gain, milder adipose expansion, and higher plasma levels of triglycerides than the wild-type mice. These changes were reversed by replenishing CORT to L/L mice. When examining the expression levels of various molecules linked to lipid uptake and de novo lipogenesis in CORT-induced adipose expansion, we observed a reduction in the expression of adipose preadipocyte factor 1 (Pref-1), a key regulator in adipogenesis. In 3T3-L1 preadipocyte-like cells, dexamethasone, an agonist of the glucocorticoid receptor, also reduced expressions of Pref-1 and facilitated intracellular accumulation of lipids.

CONCLUSIONS

Our results suggest that fat ingestion-induced release of CORT contributes to adipose expansion and development of obesity and highlight the pathogenic role of CORT-mediated downregulation of adipose Pref-1 in diet-induced obesity.

Uncovering the Therapeutic Potential of Lithium Chloride in Type 2 Diabetic Cardiomyopathy: Targeting Tau Hyperphosphorylation and TGF-β Signaling via GSK-3β Inhibition

Diabetic cardiomyopathy (DCM) is a major complication of type 2 diabetes mellitus (T2DM) that leads to significant morbidity and mortality. The alteration in the signaling mechanism in diabetes leading to cardiomyopathy remains unclear. The purpose of this study is to investigate the role of tauopathy in myocardial dysfunction observed in T2DM. In that regard, diabetic Sprague Dawley rats were treated with intraperitoneal injections of lithium chloride (LiCl), inhibiting tau phosphorylation. Cardiac function was evaluated, and molecular markers of myocardial fibrosis and the TGF-β signaling were analyzed. T2DM rats exhibited a decline in ejection fraction and fractional shortening that revealed cardiac function abnormalities and increased myocardial fibrosis. These changes were associated with tau hyperphosphorylation. Treating diabetic rats with LiCl attenuated cardiac fibrosis and improved myocardial function. Inhibition of GSK-3β leads to the suppression of tau phosphorylation, which is associated with a decrease in TGF-β expression and regulation of the pro-inflammatory markers, suggesting that tau hyperphosphorylation is parallelly associated with fibrosis and inflammation in the diabetic heart. Our findings provide evidence of a possible role of tau hyperphosphorylation in the pathogenesis of DCM through the activation of TGF-β and by inducing inflammation. Targeting the inhibition of tau phosphorylation may offer novel therapeutic approaches to reduce DCM burden in T2DM patients.

High-fat diet-induced obesity accelerates the progression of spontaneous osteoarthritis in senescence-accelerated mouse prone 8

OBJECTIVES

Ageing and obesity are major risk factors for osteoarthritis (OA), a widespread disease currently lacking efficient treatments. Senescence-accelerated mouse prone 8 (SAMP8) display early onset ageing phenotypes, including OA. This study investigates the impacts of high-fat diet (HFD)-induced obesity on OA development in SAMP8.

METHODS

SAMP8 at 5 weeks were fed either a normal chow diet or an HFD for 10 weeks to induce obesity. Parameters related to obesity, liver function, and lipid and glucose metabolism were analysed. At 14 weeks of age, knee joint pathology, bone mineral density, and muscle strength were assessed. Immunohistochemistry and TUNEL staining were performed to evaluate markers for cartilage degeneration and chondrocyte apoptosis.

RESULTS

At 14 weeks of age, HFD-induced obesity increased liver and adipose tissue inflammation in SAMP8 without further exacerbating diabetes. Histological scoring revealed aggravated cartilage, menisci deterioration, and synovitis, while no further loss of bone mineral density or muscle strength was observed. Increased chondrocyte apoptosis was detected in knee joints following HFD feeding.

CONCLUSIONS

Ten weeks of HFD feeding promotes spontaneous OA progression in 14-week-old SAMP8, potentially via liver damage that subsequently leads to chondrocyte apoptosis. This ageing-obese mouse model may prove valuable for further exploration of spontaneous OA pathophysiology.

The effects of a diet with high fat content from lard on the health and adipose-markers' mRNA expression in mice

Pork is one type of the most frequently consumed meat with about 30% globally. Thus, the questions regarding to the health effects of diet with high fat content from lard are raised. Here, we developed a model of mice fed with high fat (HF) from lard to investigate and have more insights on the effects of long-time feeding with HF on health. The results showed that 66 days on HF induced a significant gain in the body weight of mice, and this weight gain was associated to the deposits in the white fat, but not brown fat. The glucose tolerance, not insulin resistance, in mice was decreased by the HF diet, and this was accompanied with significantly higher blood levels of total cholesterol and triglycerides. Furthermore, the weight gains in mice fed with HF seemed to link to increased mRNA levels of adipose biomarkers in lipogenesis, including Acly and Acaca genes, in white fat tissues. Thus, our study shows that a diet with high fat from lard induced the increase in body weight, white fat depots' expansion, disruption of glucose tolerance, blood dyslipidemia, and seemed to start affecting the mRNA expression of some adipose biomarkers in a murine model.

Exploring the efficacy of photodynamic antimicrobial chemotherapy on diabetic foot ulcers in rats

We investigate the efficacy of photodynamic antimicrobial chemotherapy (PACT) and its combination with an antibiotic in the treatment of diabetic foot ulcers (DFUs) in rats using a novel cationic amino acid porphyrin-based photosensitizer. The research findings demonstrate that the combination of novel cationic photosensitizer-mediated PACT and an antibiotic exhibits significant therapeutic efficacy in treating deep ulcers in a rat model of DFUs. Moreover, the PACT + Antibiotic group displays enhanced angiogenesis, improved tissue maturation, and superior wound healing effect. Micro-computed tomography examination showed that the periosteal reaction was most obvious in the PACT + Antibiotic group. The cortical bone volume ratio (BV/TV), the bone mineral density, and trabecular thickness were significantly higher in the PACT + Antibiotic group than in the model group (p < 0.05). The combination of PACT and antibiotic plays a sensitizing therapeutic role, which provides a new idea for the clinical treatment of DFUs.

Acidic Nanoparticles Restore Lysosomal Acidification and Rescue Metabolic Dysfunction in Pancreatic β-Cells under Lipotoxic Conditions

Type 2 diabetes (T2D), a prevalent metabolic disorder lacking effective treatments, is associated with lysosomal acidification dysfunction, as well as autophagic and mitochondrial impairments. Here, we report a series of biodegradable poly(butylene tetrafluorosuccinate-co-succinate) polyesters, comprising a 1,4-butanediol linker and varying ratios of tetrafluorosuccinic acid (TFSA) and succinic acid as components, to engineer lysosome-acidifying nanoparticles (NPs). The synthesized NPs are spherical with diameters of ≈100 nm and have low polydispersity and good stability. Notably, TFSA NPs, which are composed entirely of TFSA, exhibit the strongest degradation capability and superior acidifying properties. We further reveal significant downregulation of lysosomal vacuolar (H+)-ATPase subunits, which are responsible for maintaining lysosomal acidification, in human T2D pancreatic islets, INS-1 β-cells under chronic lipotoxic conditions, and pancreatic tissues of high-fat-diet (HFD) mice. Treatment with TFSA NPs restores lysosomal acidification, autophagic function, and mitochondrial activity, thereby improving the pancreatic function in INS-1 cells and HFD mice with lipid overload. Importantly, the administration of TFSA NPs to HFD mice reduces insulin resistance and improves glucose clearance. These findings highlight the therapeutic potential of lysosome-acidifying TFSA NPs for T2D.

Saturated fatty acid concentrations are predictive of insulin sensitivity and beta cell compensation in dogs

Chronic feeding of a high fat diet (HFD) in preclinical species induces broad metabolic dysfunction characterized by body weight gain, hyperinsulinemia, dyslipidemia and impaired insulin sensitivity. The plasma lipidome is not well characterized in dogs with HFD-induced metabolic dysfunction. We therefore aimed to describe the alterations that occur in the plasma lipid composition of dogs that are fed a HFD and examine the association of these changes with the clinical signs of metabolic dysfunction. Dogs were fed a normal diet (ND) or HFD for 12 weeks. Insulin sensitivity (SI) and beta cell compensation (AIRG) were assessed through an intravenous glucose tolerance test (IVGTT) and serum biochemistry was analyzed before the introduction of HFD and again after 12 weeks of continued ND or HFD feeding. Plasma lipidomics were conducted prior to the introduction of HFD and again at week 8 in both ND and HFD-fed dogs. 12 weeks of HFD feeding resulted in impaired insulin sensitivity and increased beta cell compensation measured by SI (ND mean: 11.5 [mU/l]-1 min-1, HFD mean: 4.7 [mU/l]-1 min-1) and AIRG (ND mean: 167.0 [mU/l]min, HFD mean: 260.2 [mU/l]min), respectively, compared to dogs fed ND over the same duration. Chronic HFD feeding increased concentrations of plasma lipid species and deleterious fatty acids compared to dogs fed a ND. Saturated fatty acid (SFA) concentrations were significantly associated with fasting insulin (R2 = 0.29), SI (R2 = 0.49) and AIRG (R2 = 0.37) in all dogs after 12 weeks, irrespective of diet. Our results demonstrate that chronic HFD feeding leads to significant changes in plasma lipid composition and fatty acid concentrations associated with metabolic dysfunction. High SFA concentrations may be predictive of deteriorated insulin sensitivity in dogs.

Vaccine Targeting Alpha 1D-Adrenergic Receptor Improved Metabolic Syndrome in Mice

PURPOSE

Metabolic syndrome (MetS) is a complex chronic disease that includes obesity and hypertension, with rising evidence demonstrating that sympathetic nervous system (SNS) activation plays a key role. Our team designed a therapeutic vaccine called ADRQβ-004 targeting the α1D-adrenergic receptor (α1D-AR). This study was performed to investigate whether the ADRQβ-004 vaccine improves MetS by modulating SNS activity.

METHODS

C57BL/6N mice were fed a high-fat diet (HFD) and Nω-nitro-L-arginine methyl ester (L-NAME) combination diet for 18 weeks to elicit MetS. The MetS mice were subcutaneously immunized with the ADRQβ-004 vaccine four times to evaluate the therapeutic efficacy in obesity and hypertension and other associated abnormalities related to MetS by conducting echocardiographic, histological, and biochemical analyses.

RESULTS

The ADRQβ-004 vaccine induced strong antibody production and maintained a high anti-ADR-004 antibody titer in MetS mice. The ADRQβ-004 vaccine improved obesity (P < 0.001) and decreased systolic blood pressure (P < 0.001). Improvements in dysregulated glucose homeostasis and dyslipidemia resulting from the ADRQβ-004 vaccine were also confirmed. Furthermore, the ADRQβ-004 vaccine attenuated cardiovascular functional (P = 0.015) and structural changes (P < 0.001), decreased fat accumulation (P = 0.012) and inflammation (P = 0.050) in the epididymal white adipose tissue, and alleviated hepatic steatosis (P = 0.043) involved in MetS. Moreover, the ADRQβ-004 vaccine improved systematic and visceral organs SNS activities in the MetS.

CONCLUSION

This study demonstrated for the first time that the ADRQβ-004 vaccine targeting α1D-AR improved obesity, hypertension, dyslipidemia, and dysglycemia, and further reduced end-organ damage, which may provide new motivation for MetS research.

A short-term rodent model for non-alcoholic steatohepatitis induced by a high-fat diet and carbon tetrachloride

Several models of mice-fed high-fat diets have been used to trigger non-alcoholic steatohepatitis and some chemical substances, such as carbon tetrachloride. The present study aimed to evaluate the joint action of a high-fat diet and CCl4 in developing a short-term non-alcoholic steatohepatitis model. C57BL6/J mice were divided into two groups: standard diet-fed (SD), the high-fat diet-fed (HFD) and HFD + fructose-fed and carbon tetrachloride (HFD+CCl4). The animals fed with HFD+CCl4 presented increased lipid deposition compared with both SD and HFD mice. Plasma cholesterol was increased in animals from the HFD+CCl4 group compared with the SD and HFD groups, without significant differences between the SD and HFD groups. Plasma triglycerides showed no significant difference between the groups. The HFD+CCl4 animals had increased collagen deposition in the liver compared with both SD and HFD groups. Hydroxyproline was also increased in the HFD+CCl4 group. Liver enzymes, alanine aminotransferase and aspartate aminotransferase, were increased in the HFD+CCl4 group, compared with SD and HFD groups. Also, CCl4 was able to trigger an inflammatory process in the liver of HFD-fed animals by promoting an increase of ∼2 times in macrophage activity, ∼6 times in F4/80 gene expression, and pro-inflammatory cytokines (IL-1b and TNFa), in addition to an increase in inflammatory pathway protein phosphorylation (IKKbp). HFD e HFD+CCl4 animals increased glucose intolerance compared with SD mice, associated with reduced insulin-stimulated AKT activity in the liver. Therefore, our study has shown that short-term HFD feeding associated with fructose and CCl4 can trigger non-alcoholic steatohepatitis and cause damage to glucose metabolism.

The Effect of Bifidobacterium animalis subsp. lactis MN-Gup on Glucose Metabolism, Gut Microbiota, and Their Metabolites in Type 2 Diabetic Mice

Probiotics have garnered increasing attention as a potential therapeutic approach for type 2 diabetes mellitus (T2DM). Previous studies have confirmed that Bifidobacterium animalis subsp. lactis MN-Gup (MN-Gup) could stimulate the secretion of glucagon-like peptide-1 (GLP-1) in NCI-H716 cells, but whether MN-Gup has a hypoglycemic effect on T2DM in vivo remains unclear. In this study, a T2DM mouse model was constructed, with a high-fat diet and streptozotocin in mice, to investigate the effect of MN-Gup on diabetes. Then, different doses of MN-Gup (2 × 109 CFU/kg, 1 × 1010 CFU/kg) were gavaged for 6 weeks to investigate the effect of MN-Gup on glucose metabolism and its potential mechanisms. The results showed that a high-dose of MN-Gup significantly reduced the fasting blood glucose (FBG) levels and homeostasis model assessment-insulin resistance (HOMA-IR) of T2DM mice compared to the other groups. In addition, there were significant increases in the short-chain fatty acids (SCFAs), especially acetate, and GLP-1 levels in the MN-Gup group. MN-Gup increased the relative abundance of Bifidobacterium and decreased the number of Escherichia-Shigella and Staphylococcus. Moreover, the correlation analysis revealed that Bifidobacterium demonstrated a significant positive correlation with GLP-1 and a negative correlation with the incremental AUC. In summary, this study demonstrates that Bifidobacterium animalis subsp. lactis MN-Gup has significant hypoglycemic effects in T2DM mice and can modulate the gut microbiota, promoting the secretion of SCFAs and GLP-1.

Anti-obesity effects of potential probiotic Lactobacillus strains isolated from Mongolian fermented dairy products in high-fat diet-induced obese rodent model

This study aims to investigate the anti-obesity properties of lactic acid bacteria (LAB) isolated from fermented dairy products such as "Airag" and "Khoormog" in Mongolia. These traditional dairy products are widely used in Mongolia and believe in having potential probiotic, anti-diabetes, anti-cancer, and anti-tuberculosis properties and are made from unheated two-humped camel milk and mare milk, respectively. We chose three LAB strains based on their probiotic characteristics, including tolerance of gastric and bile acids. Then we checked the anti-obesity activity of probiotic strains in vivo. An animal model was evaluated in twenty male C57BL/6J mice by inducing obesity with a high-fat diet (HFD), which was divided into five groups: regular diet group (Negative control), HFD group (Positive control), HFD with Lacticaseibacillus paracasei X-1 (X-1), Lacticaseibacillus paracasei X-17 (X-17), and Limosilactobacillus fermentum BM-325 (BM-325). For six weeks, 5 × 109 colony-forming units (CFU) of bacteria were given orally to the LAB-fed groups. Fasting blood glucose (FBG), lipid profiles, organ index, and organ morphology were all measured. The probiotic strains suppressed growth in adipose cell volume, stabilized FBG, reduced liver cell degeneration, and slowed HFD-induced body weight gain. The results suggest that some strains increase general metabolism while lowering body weight.

Fucoidan Improves Early Stage Diabetic Nephropathy via the Gut Microbiota-Mitochondria Axis in High-Fat Diet-Induced Diabetic Mice

Diabetic nephropathy (DN) is a common microvascular complication of diabetes. Fucoidan, a polysaccharide containing fucose and sulfate group, ameliorates DN. However, the underlying mechanism has not been fully understood. This study aimed to explore the effects and mechanism of fucoidan on DN in high-fat diet-induced diabetic mice. A total of 90 C57BL/6J mice were randomly assigned to six groups (n = 15) as follows: normal control (NC), diabetes mellitus (DM), metformin (MTF), low-dose fucoidan (LFC), medium-dose fucoidan (MFC), and high-dose fucoidan (HFC). A technique based on fluorescein isothiocyanate (FITC-sinistin) elimination kinetics measured percutaneously was applied to determine the glomerular filtration rate (GFR). After 24 weeks, the mice were sacrificed and an early stage DN model was confirmed by GFR hyperfiltration, elevated urinary creatinine, normal urinary albumin, tubulointerstitial fibrosis, and glomerular hypertrophy. Fucoidan significantly improved the GFR hyperfiltration and renal fibrosis. An enriched SCFAs-producing bacteria and increased acetic concentration in cecum contents were found in fucoidan groups, as well as increased renal ATP levels and improved mitochondrial dysfunction. The renal inflammation and fibrosis were ameliorated through inhibiting the MAPKs pathway. In conclusion, fucoidan improved early stage DN targeting the microbiota-mitochondria axis by ameliorating mitochondrial oxidative stress and inhibiting the MAPKs pathway.

Current advancement in the preclinical models used for the assessment of diabetic neuropathy

Diabetic neuropathy is one of the prevalent and debilitating microvascular complications of diabetes mellitus, affecting a significant portion of the global population. Relational preclinical animal models are essential to understand its pathophysiology and develop effective treatments. This abstract provides an overview of current knowledge and advancements in such models. Various animal models have been developed to mimic the multifaceted aspects of human diabetic neuropathy, including both type 1 and type 2 diabetes. These models involve rodents (rats and mice) and larger animals like rabbits and dogs. Induction of diabetic neuropathy in these models is achieved through chemical, genetic, or dietary interventions, such as diabetogenic agents, genetic modifications, or high-fat diets. Preclinical animal models have greatly contributed to studying the intricate molecular and cellular mechanisms underlying diabetic neuropathy. They have shed light on hyperglycemia-induced oxidative stress, neuroinflammation, mitochondrial dysfunction, and altered neurotrophic factor signaling. Additionally, these models have allowed for the investigation of morphological changes, functional alterations, and behavioral manifestations associated with diabetic neuropathy. These models have also been crucial for evaluating the efficacy and safety of potential therapeutic interventions. Novel pharmacological agents, gene therapies, stem cell-based approaches, exercise, dietary modifications, and neurostimulation techniques have been tested using these models. However, limitations and challenges remain, including physiological differences between humans and animals, complex neuropathy phenotypes, and the need for translational validation. In conclusion, preclinical animal models have played a vital role in advancing our understanding and management of diabetic neuropathy. They have enhanced our knowledge of disease mechanisms, facilitated the development of novel treatments, and provided a platform for translational research. Ongoing efforts to refine and validate these models are crucial for future treatment developments for this debilitating condition.

Changed regulation of granulocyte NADPH oxidase activity in the mouse model of obesity-induced type 2 diabetes mellitus

NADPH oxidase is a target of hyperglycemia in type 2 diabetes mellitus (T2DM), which causes dysregulation of enzyme. Alterations in regulation of NADPH oxidase activity mediated receptor and non-receptor signaling in bone marrow granulocytes of mice with obesity-induced T2DM were studied. The animals fed high fat diet (516 kcal/100 g) for 16 weeks. NADPH oxidase-related generation of reactive species (RS) at normo- and hyperthermia was estimated using chemiluminescent analysis. The redox status of the cells was assessed by Redox Sensor Red CC-1. Baseline biochemical indicators in blood (glucose, cholesterol, HDL and LDL levels) were significant higher in T2DM mice versus controls. Using specific inhibitors, signaling mediated by formyl peptide receptors (FPRs) to NADPH oxidase was shown to involve PLC, PKC, cytochrome p450 in both control and T2DM groups and PLA2 in controls. In T2DM regulation of NADPH oxidase activity via mFpr1, a high-affinity receptors, occurred with a significant increase of the role of PKC isoforms and suppression of PLA2 participation. Significant differences between this regulation via mFpr2, low-affinity receptors, were not found. Non-receptor activation of NADPH oxidase with ionomycin (Ca2+ ionophore) or phorbol ester (direct activator of PKC isoforms) did not revealed differences in the kinetic parameters between groups at 37 °C and 40 °C. When these agents were used together (synergistic effect), lower sensitivity of cells to ionophore was observed in T2DM at both temperatures. Redox status in responses to opsonized zymosan was higher in T2DM mice at 37 °C and similar to control levels at 40 °C. ROC-analysis identified Tmax, RS production and effect of opsonized zymosan as the most significant predictors for discriminating between groups. It was concluded that Ca2+-dependent/PKC-mediated regulation of NADPH oxidase activity was altered in BM granulocytes from diabetic mice.

Tibial cortex transverse transport regulates Orai1/STIM1-mediated NO release and improve the migration and proliferation of vessels via increasing osteopontin expression

Background

Diabetic foot is a major complication of diabetes. The bone transverse transport method could be applied in clinics for treatment, which could improve the metabolism of the tissues via lasting distraction forces. However, the process' specific regulating mechanism is still unknown.

Methods

Based on the notion that the healing of bones involves the recruitment of calcium ions, in this study, we established the model of tibial cortex transverse transport (TTT) on rats and then used tissue immunologic detection, such as the double fluorescent staining to explore the expression of the calcium channels' calcium release-activated calcium modulator 1 (Orai1)/stromal interaction molecule 1 (STIM1), which belong to the store-operated calcium entry (SOCE) signaling pathways on the tissues around the bone transport area. By using the laser capture microdissection (LCM) tool, we acquired samples of tissues around the bone and endeavored to identify pivotal protein molecules. Subsequently, we validated the functions of key protein molecules through in vitro and in vivo experiments.

Results

After protein profile analysis, we found the differentially expressed key protein osteopontin (OPN). The in vitro experiments verified that, being stimulated by OPN, the migration, proliferation, and angiogenesis of human umbilical vein endothelial cells (HUVEC) were observed to be enhanced. The activation of Orai1/STIM1 might increase the activity of endothelial nitric oxide synthase (eNOS) and its effect on releasing nitric oxide (NO). Subsequently, the migration and proliferation of the HUVECs are improved, which ultimately accelerates wound healing. These signaling pathway was also observed in the OPN-stimulated healing process of the skin wound surface of diabetic mice.

Conclusion

This study identifies the molecular biological mechanism of OPN-benefited the migration and proliferation of the HUVECs and provides ideas for searching for new therapeutic targets for drugs that repair diabetes-induced wounds to replace invasive treatment methods.

The translational potential of this article

The OPN is highly expressed in the tissues surrounding the TTT bone transfer area, which may possibly stimulate the activation of eNOS to increase NO release through the SOCE pathway mediated by Orai1/STIM1. This mechanism may play a significant role in the angiogenesis of diabetic foot's wounds promoted by TTT, providing new therapeutic strategies for the non-surgical treatment for this disease.

Type 2 diabetes and succinate: unmasking an age-old molecule

Beyond their conventional roles in intracellular energy production, some traditional metabolites also function as extracellular messengers that activate cell-surface G-protein-coupled receptors (GPCRs) akin to hormones and neurotransmitters. These signalling metabolites, often derived from nutrients, the gut microbiota or the host's intermediary metabolism, are now acknowledged as key regulators of various metabolic and immune responses. This review delves into the multi-dimensional aspects of succinate, a dual metabolite with roots in both the mitochondria and microbiome. It also connects the dots between succinate's role in the Krebs cycle, mitochondrial respiration, and its double-edge function as a signalling transmitter within and outside the cell. We aim to provide an overview of the role of the succinate-succinate receptor 1 (SUCNR1) axis in diabetes, discussing the potential use of succinate as a biomarker and the novel prospect of targeting SUCNR1 to manage complications associated with diabetes. We further propose strategies to manipulate the succinate-SUCNR1 axis for better diabetes management; this includes pharmacological modulation of SUCNR1 and innovative approaches to manage succinate concentrations, such as succinate administration and indirect strategies, like microbiota modulation. The dual nature of succinate, both in terms of origins and roles, offers a rich landscape for understanding the intricate connections within metabolic diseases, like diabetes, and indicates promising pathways for developing new therapeutic strategies.

The BET inhibitor JQ1 targets fat metabolism and counteracts obesity

INTRODUCTION

Obesity, one of the most frequent health problems in the adult population, is a condition characterized by excessive white adipose tissue accumulation and accompanied by the increased risk to develop other disorders such as type II diabetes, cardiovascular disorders, physical disability, frailty and sarcopenia. Total fat mass frequently increases during aging, often coexisting with sarcopenia, thus resulting in an emerging condition defined sarcopenic obesity (SO). Our previous data demonstrated the relevant role of the bromo and extra-terminal domain (BET) proteins inhibitor JQ1 in attenuating inflammation and fibrosis in sarcopenic mice. Moreover, we preliminarily observed that JQ1 administration markedly reduces white adipose tissue mass, suggesting a potential role of BET proteins on visceral fat deposition during aging.

OBJECTIVES

Starting from those observations, the aim of this study was to investigate the ability of JQ1 to reduce adiposity in a chronic diet-induced obesity (DIO) mouse model mimicking the human metabolic syndrome.

METHODS

Male C57BL/6J mice were divided in subgroups, either fed a standard diet or a high fat diet for 22 or 12 weeks, treated over the last 14 days with JQ1 or with vehicle.

RESULTS

The results showed that JQ1 administration reduces fat mass, preserving skeletal muscle mass and function. A direct JQ1 lipolytic effect was demonstrated on mature adipocyte cultures. JQ1-mediated loss of adipose tissue mass was not associated with systemic inflammation or with lipid accumulation in muscle and liver. JQ1 administration did not impinge on skeletal muscle metabolism and oxidative capability, as shown by the lack of significant impact on mitochondrial mass and biogenesis.

CONCLUSION

In conclusion, the current data highlight a potential benefit of JQ1 administration to counteract obesity, suggesting epigenetic modulation as a prospective target in the treatment of obesity and sarcopenic obesity, despite the underlying multiorgan molecular mechanism is still not completely elucidated.

Dysregulated cysteine metabolism leads to worsened liver pathology in diabetes-tuberculosis comorbid condition

Diabetes mellitus (DM) is a risk factor for developing active tuberculosis (TB) with a 3-fold increase in susceptibility and a 4-fold higher relapse rate. With increasing DM prevalence in TB endemic regions, understanding pathophysiological changes associated with DM-TB comorbidity is imperative. In this study, streptozotocin (STZ)-induced DM C57BL/6 mice were aerosol infected with low dose (100-120 CFU) Mycobacterium tuberculosis H37Rv. At 3 weeks post infection (w.p.i.), multiple tissue mycobacterial load and metabolites were profiled. The liver proteome of DM-TB and controls were analyzed using quantitative proteomics, and multi-omics data were integrated. DM-TB mice showed dysregulated multi-tissue (lungs, liver, brain, kidney and thigh muscle) metabolism. In contrast, the mycobacterial burden in the lung, spleen and liver was similar at 3 w.p.i. in DM-TB and TB groups. Enrichment analysis of deregulated liver metabolites (n = 20; log2DM-TB/TB>±1.0) showed significant perturbation in cysteine-methionine, glycine-serine, BCAA and fatty acid metabolism. 60 out of 1660 identified liver proteins showed deregulation (log2DM-TB/TB>±1.0) and contributed from perturbed cysteine-methionine metabolism corroborating metabolomics data. In addition, amino acid biosynthesis, retinol metabolism and polyol biosynthetic process were also differentially enriched in the livers of DM-TB groups. Global correlation analysis of liver metabolome and proteome data showed a strong association between aspartic acid, pyruvic acid, leucine and isoleucine with CYP450 enzymes involved in retinol metabolism, while iminodiacetic acid, isoleucine and γ-aminobutyric acid (GABA) strong positive correlation involved in cysteine metabolism. Targeting perturbed cysteine metabolism using micro molecules, like DL-Propargylglycine, might help prevent liver damage in DM-TB comorbid conditions.

NADPH oxidase 4 in mouse β cells participates in inflammation on chronic nutrient overload

OBJECTIVE

By exposing mice carrying a deletion of NADPH oxidase isoform 4, NOX4, specifically in pancreatic β cells (βNOX4-/-) to nutrient excess stimulated by a high-fat diet (HFD), this study aimed to elucidate the role of β-cell redox status in the development of meta-inflammation within the diabetic phenotype.

METHODS

The authors performed basic phenotyping of βNOX4-/- mice on HFD involving insulin and glycemic analyses, histochemistry of adipocytes, indirect calorimetry, and cytokine analyses. To characterize local inflammation, the study used caspase-1 activity assay, interleukin-1β immunochemistry, and real-time polymerase chain reaction during coculturing of β cells with macrophages.

RESULTS

The phenotype of βNOX4-/- mice on HFD was not associated with hyperinsulinemia and hyperglycemia but showed accumulation of excessive lipids in epididymal fat and β cells. Surprisingly, mice showed significantly reduced systemic inflammation. Decreased interleukin-1β protein levels and downregulated NLRP3-inflammasome activity were observed on chronic glucose overload in βNOX4-/- isolated islets and NOX4-silenced INS1-E cells resulting in attenuated proinflammatory polarization of macrophages/monocytes in vitro and in situ and reduced local islet inflammation.

CONCLUSIONS

Experimental evidence suggests that NOX4 pro-oxidant activity in β cells is involved in NLRP3-inflammasome activation during chronic nutrient overload and participates in local inflammatory signaling and perhaps toward peripheral tissues, contributing to a diabetic inflammatory phenotype.

High-Fat Diets in Animal Models of Alzheimer's Disease: How Can Eating Too Much Fat Increase Alzheimer's Disease Risk?

High dietary intake of saturated fatty acids is a suspected risk factor for neurodegenerative diseases, including Alzheimer's disease (AD). To decipher the causal link behind these associations, high-fat diets (HFD) have been repeatedly investigated in animal models. Preclinical studies allow full control over dietary composition, avoiding ethical concerns in clinical trials. The goal of the present article is to provide a narrative review of reports on HFD in animal models of AD. Eligibility criteria included mouse models of AD fed a HFD defined as > 35% of fat/weight and western diets containing > 1% cholesterol or > 15% sugar. MEDLINE and Embase databases were searched from 1946 to August 2022, and 32 preclinical studies were included in the review. HFD-induced obesity and metabolic disturbances such as insulin resistance and glucose intolerance have been replicated in most studies, but with methodological variability. Most studies have found an aggravating effect of HFD on brain Aβ pathology, whereas tau pathology has been much less studied, and results are more equivocal. While most reports show HFD-induced impairment on cognitive behavior, confounding factors may blur their interpretation. In summary, despite conflicting results, exposing rodents to diets highly enriched in saturated fat induces not only metabolic defects, but also cognitive impairment often accompanied by aggravated neuropathological markers, most notably Aβ burden. Although there are important variations between methods, particularly the lack of diet characterization, these studies collectively suggest that excessive intake of saturated fat should be avoided in order to lower the incidence of AD.

Strategy for the Identification of Host-Defense Peptides in Frog Skin Secretions with Therapeutic Potential as Antidiabetic Agents

Several amphibian peptides that were first identified on the basis of their antimicrobial or cytotoxic properties have subsequently shown potential for development into agents for the treatment of patients with Type 2 diabetes. A strategy is presented for the isolation and characterization of such peptides that are present in norepinephrine-stimulated skin secretions from a range of frog species. The methodology involves (1) fractionation of the secretions by reversed-phase HPLC, (2) identification of fractions containing components that stimulate the rate of release of insulin from BRIN-BD11 clonal β-cells without simultaneously stimulating the release of lactate dehydrogenase, (3) identification of active peptides in the fractions in the mass range 1-6 kDa by MALDI-ToF mass spectrometry, (4) purification of the peptides to near homogeneity by further reversed-phase HPLC on various column matrices, and (5) structural characterization by automated Edman degradation. The effect of synthetic replicates of the active peptides on glucose homeostasis in vivo may be evaluated in appropriate animal models of Type 2 diabetes such as db/db mice and mice fed a high fat diet to produce obesity, glucose intolerance, and insulin resistance.

DNA methylation regulates pancreatic gene expression and links maternal high-fat diet to the offspring glucose metabolism

Maternal high-fat diet (HFD) is related to an increased risk of glucose metabolism disorders throughout the whole life of offspring. The pancreas is a glucose homeostasis regulator. Accumulating evidence has revealed that maternal HFD affects offspring pancreas structure and function. However, the potential mechanism remains unclear. In this study, the mouse dam was fed with HFD or control diet (CD) during prepregnancy, pregnancy and lactation. The pancreatic insulin secretion function and islet genome methylome of offspring were analyzed. Pancreatic islet specific gene methylation was detected by using MeDIP qPCR. The results showed that body weight, blood glucose after oral glucose loads, fasting serum insulin, and HOMA-IR index values were significantly higher in male 12-week-old offspring from HFD dams than in the offspring from CD dams. Maternal HFD induced insulin secretion defects in male offspring. Compared with that in maternal CD group, methylation of the Abcc8 and Kcnj11 genes was increased in maternal HFD group in male offspring pancreatic islets. Furthermore, the expression levels of Abcc8 and Kcnj11 were downregulated by intrauterine exposure to a maternal HFD. In summary, maternal HFD results in a long-term functional disorder of the pancreas that is involved in insulin secretion-related gene DNA hypermethylation.

Acarbose reduces Pseudomonas aeruginosa respiratory tract infection in type 2 diabetic mice

BACKGROUND

Type 2 diabetes mellitus (T2DM) is widely prevalent worldwide, and respiratory tract infections (RTIs) have become the primary cause of death for T2DM patients who develop concurrent infections. Among these, Pseudomonas aeruginosa infection has been found to exhibit a high mortality rate and poor prognosis and is frequently observed in bacterial infections that are concurrent with COVID-19. Studies have suggested that acarbose can be used to treat T2DM and reduce inflammation. Our objective was to explore the effect of acarbose on P. aeruginosa RTI in T2DM individuals and elucidate its underlying mechanism.

METHODS

High-fat diet (HFD) induction and P. aeruginosa inhalation were used to establish a RTI model in T2DM mice. The effect and mechanism of acarbose administered by gavage on P. aeruginosa RTI were investigated in T2DM and nondiabetic mice using survival curves, pathological examination, and transcriptomics.

RESULTS

We found that P. aeruginosa RTI was more severe in T2DM mice than in nondiabetic individuals, which could be attributed to the activation of the NF-κB and TREM-1 signaling pathways. When acarbose alleviated P. aeruginosa RTI in T2DM mice, both HIF-1α and NF-κB signaling pathways were inhibited. Furthermore, inhibition of the calcium ion signaling pathway and NF-κB signaling pathway contributed to the attenuation of P. aeruginosa RTI by acarbose in nondiabetic mice.

CONCLUSIONS

This study confirmed the attenuating effect of acarbose on P. aeruginosa RTIs in T2DM and nondiabetic mice and investigated its mechanism, providing novel support for its clinical application in related diseases.

GPR120/FFAR4: A Potential New Therapeutic Target for Inflammatory Bowel Disease

Inflammatory bowel disease, whose major forms are Crohn's disease and ulcerative colitis, is characterized by chronic inflammation of the gut due to the loss of tolerance toward antigens normally contained in the gut lumen. G protein-coupled receptor (GPR) 120 has gained considerable attention as a potential therapeutic target for metabolic disorders due to its implication in the production of the incretin hormone glucagon-like peptide 1 and the secretion of cholecystokinin. Recent studies have also highlighted the role of GPR120 in regulating immune system activity and inflammation. GPR120, expressed by intestinal epithelial cells, proinflammatory macrophages, enteroendocrine L cells, and CD4+ T cells, suppresses proinflammatory and enhances anti-inflammatory cytokine production, suggesting that GPR120 might have a pivotal role in intestinal inflammation and represent a possible therapeutic target in inflammatory bowel disease. This narrative review aims at summarizing the role of GPR120 in the maintenance of intestinal homeostasis through the analysis of the most recent studies.

Based on network pharmacology to explore the effect and mechanism of Yipibushen decoction in improving obese type 2 diabetes mellitus with oligoasthenotspermia

ETHNOPHARMACOLOGICAL RELEVANCE

A traditional Chinese medicine experience compound known as Yipibushen (YPBS) decoction stimulates qi and nourishes yin, stimulates the kidney and solid essence, dissolves phlegm and eliminates stasis. YPBS decoction has proven to be successful in treating obese type 2 diabetes mellitus with oligoasthenotspermia in clinical settings. Nevertheless, the pharmacological mechanism is not understood.

AIM OF THE STUDY

Investigating the mechanism of action of YPBS decoction in enhancing the obese type 2 diabetes mellitus with oligoasthenotspermia involved network pharmacology and animal validation techniques.

METHODS AND MATERIALS

The YPBS Decoction' active components were found in the TCMSP database and their targets were identified using UniProtKB. Additionally, targets for the obese type 2 diabetes mellitus with oligoasthenotspermia were found in the GeneCard, DisGeNet, TTD and OMIM databases. The intersection of active ingredients, the obese type 2 diabetes mellitus with oligoasthenotspermia was chosen as the intersection target. The protein-protein interaction (PPI) network of the intersection target was built with the aid of Cytoscape 3.9.1, the core target of PPI was obtained through software analysis in R-project, GO enrichment and KEGG enrichment analysis was carried out on the core target. Finally, animal experiments were used to verify the intersection target.

RESULTS

The research revealed 74 intersection targets of YPBS decoction active ingredients in the obese type 2 diabetes mellitus with oligoasthenotspermia. There were also 18 PPI core targets, GO enrichment analysis of PPI core targets involving response to oxidative stress, membrane raft, DNA-binding transcription regulator complex and other biological processes; KEGG involving endocrine resistance, PI3K/AKT signaling pathway, apoptosis and other signal pathways. In the obese type 2 diabetes mellitus with oligoasthenotspermia mice, animal studies have shown that YPBS decoction group could decrease blood glucose levels and improve insulin resistance; improve testicular function, enhance sperm count, sperm motility, sperm viability, and decrease the malformation rate. It could increase the levels of T-SOD and GSH-Px, and decrease the MDA level. In addition to this, it could improve the amount of testosterone hormone, and enhance the expression of PI3K, p-AKT and Bcl-2.

CONCLUSION

By controlling the degree of oxidative stress and the PI3K/AKT/Bcl-2 pathway, YPBS decoction may enhance the obese type 2 diabetes mellitus with Oligoasthenotspermia, provide a scientific basis for clinical diagnosis and therapy.

A systematic review of preclinical studies exploring the role of insulin signalling in executive function and memory

Beside its involvement in somatic dysfunctions, altered insulin signalling constitutes a risk factor for the development of mental disorders like Alzheimer's disease and obsessive-compulsive disorder. While insulin-related somatic and mental disorders are often comorbid, the fundamental mechanisms underlying this association are still elusive. Studies conducted in rodent models appear well suited to help decipher these mechanisms. Specifically, these models are apt to prospective studies in which causative mechanisms can be manipulated via multiple tools (e.g., genetically engineered models and environmental interventions), and experimentally dissociated to control for potential confounding factors. Here, we provide a narrative synthesis of preclinical studies investigating the association between hyperglycaemia - as a proxy of insulin-related metabolic dysfunctions - and impairments in working and spatial memory, and attention. Ultimately, this review will advance our knowledge on the role of glucose metabolism in the comorbidity between somatic and mental illnesses.

Experimental diabetic animal models to study diabetes and diabetic complications

Diabetes is an endocrine illness involving numerous physiological systems. To understand the intricated pathophysiology and disease progression in diabetes, small animals are still the most relevant model systems, despite the availability and progression in numerous invitro and insilico research methods in recent years. In general, experimental diabetes is instigated mainly due to the effectiveness of animal models in illuminating disease etiology. Most diabetes trials are conducted on rodents, while some research is conducted on larger animals. This review will discuss the methodology and mechanisms in detail for preparing diabetic animal models, considering the following important points. The exact pathophysiology of the disease may or may not be replicated in animal models, the correct induction doses must be given and the combination of different approaches for the models is recommended to get desired results.•Animal models are essential to understand diabetes etiology and pathophysiology.•Diabetic models can be developed in both rodents and non-rodents.•Chemically induced and genetic models of diabetes are widely used to study diabetes and diabetic complications.

Inhibition of MD2 by natural product-drived JM-9 attenuates renal inflammation and diabetic nephropathy in mice

Diabetic kidney disease (DKD) is one of the severe complications of diabetes mellitus-related microvascular lesions, which remains the leading cause of end-stage kidney disease. The genesis and development of DKD is closely related to inflammation. Myeloid differentiation 2 (MD2) mediates hyperlyciemia-induced renal inflammation and DKD development and is considered as a potential therapeutic target of DKD. Here, we identified a new small-molecule MD2 inhibitor, JM-9. In vitro, JM-9 suppressed high glucose (HG) and palmitic acid (PA)-induced inflammation in MPMs, accompanied by inhibition of MD2 activation and the downstream TLR4/MyD88-MAPKs/NFκB pro-inflammatory signaling pathway. Macrophage-derived factors increased the fibrotic and inflammatory responses in renal tubular epithelial cells, which were inhibited by treating macrophages with JM-9. Then, we investigated the therapeutic effects against DKD in streptozotocin-induced type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) mouse models. Treatment with JM-9 prevented renal inflammation, fibrosis, and dysfunction by targeting MD2 in both T1DM and T2DM models. Our results show that JM-9, a new small-molecule MD2 inhibitor, protects against DKD by targeting MD2 and inhibiting MD2-mediated inflammation. In summary, JM-9 is a potential therapeutic agent for DKD.

The current state of preclinical modeling of human diabetic cardiomyopathy using rodents

The prevalence of diabetic cardiomyopathy (DCM), a specific cardiovascular complication of diabetes mellitus, has recently increased. Its pathogenesis is not fully understood, and no consensus regarding therapeutic options has been reached. Experimental studies on rodents are expected to yield further data at the preclinical stage. The present paper describes and quantitatively compares the experimental protocols intended to mimic human DCM. Experimental articles (conducted between 1990 and 2022) were identified from online electronic databases according to the PRISMA Protocol. The Cochrane Q-test was used to estimate study heterogeneity; the quality of each individual study was assessed using SYRCLE's risk of bias tool for animal studies. Sensitivity analysis was performed according to the leave-one-out method. Publication bias across studies was assessed using Egger's weighted regression and Duval and Tweedie 'trim and fill' method. A wide spectrum of protocols - from 651 papers, was examined (type 1 or 2 diabetes mellitus, as well as obesity models). They were found to vary in their presentation of DCM according to a variety of hemodynamic, echocardiographic, histopathologic and metabolic parameters. Particular attention was paid to comorbid conditions, and cardiac performance featured as systolic, diastolic dysfunction, or refractory heart failure. The majority of models displayed diastolic dysfunction, as well as myocardial fibrosis and left ventricle hypertrophy, which mimics early stage DCM. Unlike in humans, animal DCM rarely progressed to the symptomatic heart failure with reduced ejection fraction (HFrEF). The ability of individual procedures to reflect refractory heart failure or biventricular dysfunction - in the end-stage DCM has remained unclear.

L-type calcium ion channel-mediated activation of autophagy in vascular smooth muscle cells via thonningianin A (TA) alleviates vascular calcification in type 2 diabetes mellitus

Vascular calcification (VC) is associated with increased morbidity and mortality, especially among people with type 2 diabetes mellitus (T2DM). The pathogenesis of vascular calcification is incompletely understood, and until now, there have been no effective therapeutics for vascular calcification. The L-type calcium ion channel in the cell membrane is vital for Ca2+ influx. The effect of L-type calcium ion channels on autophagy remains to be elucidated. Here, the natural compound thonningianin A (TA) was found to ameliorate vascular calcification in T2DM via the activation of L-type calcium ion channels. The results showed that TA had a concentration-dependent ability to decrease the transcriptional and translational expression of the calcification-related proteins runt-related transcription factor 2 (RUNX2), bone morphogenetic protein 2 (BMP2) and osteopontin (OPN) (P < 0.01) via ATG7-dependent autophagy in β-glycerophosphate (β-GP)- and high glucose (HG)-stimulated primary mouse aortic smooth muscle cells (MASMCs) and alleviate aortic vascular calcification in VitD3-stimulated T2DM mice. However, nifedipine, an inhibitor of L-type calcium ion channels, reversed TA-induced autophagy and Ca2+ influx in MASMCs. Molecular docking analysis revealed that TA was located in the hydrophobic pocket of Cav1.2 α1C and was mainly composed of the residues Ile, Phe, Ala and Met, which confirmed the efficacy of TA in targeting the L-type calcium channel of Cav1.2 on the cell membrane. Moreover, in an in vivo model of vascular calcification in T2DM mice, nifedipine reversed the protective effects of TA on aortic calcification and the expression of the calcification-related proteins RUNX2, BMP2 and OPN (P < 0.01). Collectively, the present results reveal that the activation of cell membrane L-type calcium ion channels can induce autophagy and ameliorate vascular calcification in T2DM. Thonningianin A (TA) can target and act as a potent activator of L-type calcium ion channels. Thus, this research revealed a novel mechanism for autophagy induction via L-type calcium ion channels and provided a potential therapeutic for vascular calcification in T2DM.

The placental vasculature is affected by changes in gene expression and glycogen-rich cells in a diet-induced obesity mouse model

Maternal obesity is a risk factor for pregnancy complications. Obesity caused by a high-fat diet (HFD) may alter maternal glucose/glycogen metabolism. Here, our objective was to investigate whether the placental vasculature is altered via changes in gene expression and glycogen-rich cells using a preclinical mouse model of diet-induced obesity. We subjected female FVB/N mice to one of three feeding regimens: regular chow (RC) given at preconception and during pregnancy (Control); RC given at preconception and then a HFD during pregnancy (HFD-P); or HFD initiated 4 weeks preconception and during pregnancy (HFD-PreCP). Daily food consumption and weekly maternal weights were recorded. Maternal blood glucose levels were measured at preconception and 4 gestational epochs (E6.5-E9.5, E10.5-E12.5, E13.5-E15.5, E16.5-E19.5). At E8.5-E16.5, total RNA in placentas were isolated for gene expression analyses. Placentas were also collected for HE and periodic acid Schiff's (PAS) staining and glycogen content assays. Dams in the HFD-P and HFD-PreCP groups gained significantly more weight than controls. Pre- and antenatal glucose levels were also significantly higher (15%-30%) in HFD-PreCP dams. Expression of several placental genes were also altered in HFD dams compared with controls. Consumption of the HFD also led to phenotypic and morphologic changes in glycogen trophoblasts (GlyTs) and uterine natural killer (uNK) cells. Alterations in vascularity were also observed in the labyrinth of HFD-PreCP placentas, which correlated with decreased placental efficiency. Overall, we observed that a HFD induces gestational obesity in mice, alters expression of placental genes, affects glucose homeostasis, and alters glycogen-positive GlyTs and uNK cells. All these changes may lead to impaired placental vascular development, and thus heighten the risk for pregnancy complications.

Anthocyanins' effects on diabetes mellitus and islet transplantation

The incidence of diabetes mellitus is dramatically increasing every year, causing a huge global burden. Moreover, existing anti-diabetic drugs inevitably bring adverse reactions, and the application of islet transplantation is often limited by the damage caused by oxidative stress after transplantation. Thus, new approaches are needed to combat the growing burden of diabetes mellitus. Anthocyanins are of great nutritional interest and have been documented that have beneficial effects on chronic diseases, including diabetes mellitus. Here, we describe the health effects of anthocyanins on diabetes mellitus and islet transplantation. Epidemiological studies demonstrated that moderate intake of anthocyanins leading to a reduction in risk of diabetes mellitus. Numerous experiments both animal and clinical studies also showed positive effects of anthocyanins on prevention and treatment of diabetes and diabetic complications. These effects of anthocyanins may be related to mechanisms of improving glucose and lipid metabolism and insulin resistance, antioxidant, and anti-inflammatory activities. In addition, damage and function of pancreatic islets after transplantation are also improved by anthocyanins. These findings suggest that daily intake of anthocyanins may not only improve nutritional metabolism in healthy individuals to prevent from diabetes, but also as a supplementary treatment of diabetes mellitus and islet transplantation. Thus, more evidence is needed to better understand the potential health benefits of anthocyanins.

Intermedin alleviates diabetic vascular calcification by inhibiting GLUT1 through activation of the cAMP/PKA signaling pathway

BACKGROUND AND AIMS

Vascular calcification (VC) is regarded as an independent risk factor for cardiovascular events in type 2 diabetic patients. Glucose transporter 1 (GLUT1) involves VC. Intermedin/Adrenomedullin-2 (IMD/ADM2) is a cardiovascular protective peptide that can inhibit multiple disease-associated VC. However, the role and mechanism of IMD in diabetic VC remain unclear. Here, we investigated whether IMD inhibits diabetic VC by inhibiting GLUT1.

METHODS AND RESULTS

It was found that plasma IMD concentration was significantly decreased in type 2 diabetic patients and in fructose-induced diabetic rats compared with that in controls. Plasma IMD content was inversely correlated with fasting blood glucose level and VC severity. IMD alleviated VC in fructose-induced diabetic rats. Deficiency of Adm2 aggravated and Adm2 overexpression attenuated VC in high-fat diet-induced diabetic mice. In vitro, IMD mitigated high glucose-induced calcification of vascular smooth muscle cells (VSMCs). Mechanistically, IMD reduced advanced glycation end products (AGEs) content and the level of receptor for AGEs (RAGE). IMD decreased glucose transporter 1 (GLUT1) levels. The inhibitory effect of IMD on RAGE protein level was blocked by GLUT1 knockdown. GLUT1 knockdown abolished the effect of IMD on alleviating VSMC calcification. IMD receptor antagonist IMD17-47 and cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) inhibitor H89 abolished the inhibitory effects of IMD on GLUT1 and VSMC calcification.

CONCLUSIONS

These findings revealed that IMD exerted its anti-calcification effect by inhibiting GLUT1, providing a novel therapeutic target for diabetic VC.

Reduced SARS-CoV-2 mRNA vaccine immunogenicity and protection in mice with diet-induced obesity and insulin resistance

BACKGROUND

Obesity and type 2 diabetes mellitus (T2DM) are associated with an increased risk of severe outcomes from infectious diseases, including coronavirus disease 2019. These conditions are also associated with distinct responses to immunization, including an impaired response to widely used severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines.

OBJECTIVE

We sought to establish a connection between reduced immunization efficacy via modeling the effects of metabolic diseases on vaccine immunogenicity that is essential for the development of more effective vaccines for this distinct vulnerable population.

METHODS

A murine model of diet-induced obesity and insulin resistance was used to model the effects of comorbid T2DM and obesity on vaccine immunogenicity and protection.

RESULTS

Mice fed a high-fat diet (HFD) developed obesity, hyperinsulinemia, and glucose intolerance. Relative to mice fed a normal diet, HFD mice vaccinated with a SARS-CoV-2 mRNA vaccine exhibited significantly lower anti-spike IgG titers, predominantly in the IgG2c subclass, associated with a lower type 1 response, along with a 3.83-fold decrease in neutralizing titers. Furthermore, enhanced vaccine-induced spike-specific CD8+ T-cell activation and protection from lung infection against SARS-CoV-2 challenge were seen only in mice fed a normal diet but not in HFD mice.

CONCLUSIONS

The study demonstrated impaired immunity following SARS-CoV-2 mRNA immunization in a murine model of comorbid T2DM and obesity, supporting the need for further research into the basis for impaired anti-SARS-CoV-2 immunity in T2DM and investigation of novel approaches to enhance vaccine immunogenicity among those with metabolic diseases.

ZFYVE28 mediates insulin resistance by promoting phosphorylated insulin receptor degradation via increasing late endosomes production

Insulin resistance is associated with many pathological conditions, and an in-depth understanding of the mechanisms involved is necessary to improve insulin sensitivity. Here, we show that ZFYVE28 expression is decreased in insulin-sensitive obese individuals but increased in insulin-resistant individuals. Insulin signaling inhibits ZFYVE28 expression by inhibiting NOTCH1 via the RAS/ERK pathway, whereas ZFYVE28 expression is elevated due to impaired insulin signaling in insulin resistance. While Zfyve28 overexpression impairs insulin sensitivity and causes lipid accumulation, Zfyve28 knockout in mice can significantly improve insulin sensitivity and other indicators associated with insulin resistance. Mechanistically, ZFYVE28 colocalizes with early endosomes via the FYVE domain, which inhibits the generation of recycling endosomes but promotes the conversion of early to late endosomes, ultimately promoting phosphorylated insulin receptor degradation. This effect disappears with deletion of the FYVE domain. Overall, in this study, we reveal that ZFYVE28 is involved in insulin resistance by promoting phosphorylated insulin receptor degradation, and ZFYVE28 may be a potential therapeutic target to improve insulin sensitivity.

Effects of Treadmill Running at Different Light Cycles in Mice with Metabolic Disorders

Type 2 diabetes mellitus accounts for about 90% of cases of diabetes and is considered one of the most important problems of our time. Despite a significant number of studies on glucose metabolism, the molecular mechanisms of its regulation in health and disease remain insufficiently studied. That is why non-drug treatment of metabolic disorders is of great relevance, including physical activity. Metabolic changes under the influence of physical activity are very complex and are still difficult to understand. This study aims to deepen the understanding of the effect of physical exercise on metabolic changes in mice with diabetes mellitus. We studied the effect of forced treadmill running on body weight and metabolic parameters in mice with metabolic disorders. We developed a high-fat-diet-induced diabetic model of metabolic disorders. We exposed mice to forced treadmill running for 4 weeks. We determined glucose and insulin levels in the blood plasma biochemically and analyzed Glut-4 and citrate synthase in M. gastrocnemius muscle tissue using Western blotting. The research results show that daily treadmill running has different effects on different age groups of mice with metabolic disorders. In young-age animals, forced running has a more pronounced effect on body weight. At week 12, young obese mice had a 17% decrease in body weight. Body weight did not change in old mice. Moreover, at weeks 14 and 16, the decrease in body weight was more significant in the young mice (by 17%) compared to the old mice (by 6%) (p < 0.05). In older animals, it influences the rate of glucose uptake. At 60 min, the blood glucose in the exercised older mice decreased to 14.46 mmol/L, while the glucose concentration in the non-exercised group remained at 17 mmol/L. By 120 min, in mice subjected to exercise, the blood glucose approached the initial value (6.92 mmol/L) and amounted to 8.35 mmol/L. In the non-exercised group, this difference was 45%. The effects of physical activity depend on the time of day. The greater effect is observed when performing shift training or exercise during the time when animals are passive (light phase). In young mice, light phase training had a significant effect on increasing the content of Glut-4 in muscle tissue (84.3 ± 11.3%, p < 0.05 with control group-59.3 ± 7.8%). In aged mice, shift training caused an increase in the level of Glut-4 in muscle tissue (71.3 ± 4.1%, p < 0.05 with control group-56.4 ± 10,9%). In the group of aged mice, a lower CS level was noticed in all groups in comparison with young mice. It should also be noted that we observed that CS increased during exercise in the group of young mice, especially during light phase training. The CS content in the light phase subgroup (135.8 ± 7.0%) was higher than in the dark phase subgroup (113.3 ± 7.7%) (p = 0.0006). The CS decreased in aged chow-fed mice and increased in the high-fat-fed group. The CS content in the chow diet group (58.2 ± 5.0%) was 38% lower than in the HFD group (94.9 ± 8.8%).

Diabetic Endothelial Cell Glycogen Synthase Kinase 3β Activation Induces VCAM1 Ectodomain Shedding

Soluble cell adhesion molecules (sCAMs) are secreted ectodomain fragments of surface adhesion molecules, ICAM1 and VCAM1. sCAMs have diverse immune functions beyond their primary function, impacting immune cell recruitment and activation. Elevated sVCAM1 levels have been found to be associated with poor cardiovascular disease (CVD) outcomes, supporting VCAM1's role as a potential diagnostic marker and therapeutic target. Inhibiting sVCAM1's release or its interaction with immune cells could offer cardioprotection in conditions such as diabetes. Membrane-bound surface adhesion molecules are widely expressed in a wide variety of cell types with higher expression in endothelial cells (ECs). Still, the source of sCAMs in the circulation is not clear. Hypothesizing that endothelial cells (ECs) could be a potential source of sCAMs, this study investigated whether dysfunctional EC signaling mechanisms during diabetes cause VCAM1 ectodomain shedding. Our results from samples from an inducible diabetic mouse model revealed increased sVCAM1 plasma levels in diabetes. Protein analysis indicated upregulated VCAM1 expression and metalloproteases ADAM10 and ADAM17 in diabetic ECs. ADAMs are known for proteolytic cleavage of adhesion molecules, contributing to inflammation. GSK3β, implicated in EC VCAM1 expression, was found to be activated in diabetic ECs. GSK3β activation in control ECs increased ADAM10/17 and VCAM1. A GSK3β inhibitor reduced active GSK3β and VCAM1 ectodomain shedding. These findings suggest diabetic ECs with elevated GSK3β activity led to VCAM1 upregulation and ADAM10/17-mediated sVCAM1 shedding. This mechanism underscores the potential therapeutic role of GSK3β inhibition in reducing the levels of circulating sVCAM1. The complex roles of sCAMs extend well beyond CVD. Thus, unraveling the intricate involvement of sCAMs in the initiation and progression of vascular disease, particularly in diabetes, holds significant therapeutic potential.

Moderate- and High-Intensity Endurance Training Alleviate Diabetes-Induced Cardiac Dysfunction in Rats

Exercise training is an encouraging approach to treat cardiac dysfunction in type 2 diabetes (T2DM), but the impact of its intensity is not understood. We aim to investigate whether and, if so, how moderate-intensity training (MIT) and high-intensity interval training (HIIT) alleviate adverse cardiac remodeling and dysfunction in rats with T2DM. Male rats received standard chow (n = 10) or Western diet (WD) to induce T2DM. Hereafter, WD rats were subjected to a 12-week sedentary lifestyle (n = 8), running MIT (n = 7) or HIIT (n = 7). Insulin resistance and glucose tolerance were assessed during the oral glucose tolerance test. Plasma advanced glycation end-products (AGEs) were evaluated. Echocardiography and hemodynamic measurements evaluated cardiac function. Underlying cardiac mechanisms were investigated by histology, western blot and colorimetry. We found that MIT and HIIT lowered insulin resistance and blood glucose levels compared to sedentary WD rats. MIT decreased harmful plasma AGE levels. In the heart, MIT and HIIT lowered end-diastolic pressure, left ventricular wall thickness and interstitial collagen deposition. Cardiac citrate synthase activity, mitochondrial oxidative capacity marker, raised after both exercise training modalities. We conclude that MIT and HIIT are effective in alleviating diastolic dysfunction and pathological cardiac remodeling in T2DM, by lowering fibrosis and optimizing mitochondrial capacity.

Endothelial Insulin Resistance Exacerbates Experimental Periodontitis

Epidemiological studies suggest that the severity of periodontitis is higher in people with diabetes than in healthy individuals. Insulin resistance might play a crucial role in the pathogenesis of multiple diabetic complications and is reportedly induced in the gingiva of rodents with type 2 diabetes; however, the molecular mechanisms underlying the pathogenesis of diabetes-related periodontitis remain unclear. Therefore, we aimed to investigate whether endothelial insulin resistance in the gingiva may contribute to the pathogenesis of periodontitis as well as elucidate its underlying molecular mechanisms. We demonstrated that insulin treatment downregulated lipopolysaccharide (LPS)-induced or tumor necrosis factor α (TNFα)-induced VCAM1 expression in endothelial cells (ECs) via the PI3K/Akt activating pathway, resulting in reduced cellular adhesion between ECs and leukocytes. Hyperglycemia-induced selective insulin resistance in ECs diminished the effect of insulin on LPS- or TNFα-stimulated VCAM1 expression. Vascular endothelial cell-specific insulin receptor knockout (VEIRKO) mice exhibited selective inhibition of the PI3K/Akt pathway in the gingiva and advanced experimental periodontitis-induced alveolar bone loss via upregulation of Vcam1, Tnfα, Mcp-1, Rankl, and neutrophil migration into the gingiva compared with that in the wild-type (WT) mice despite being free from diabetes. We also observed that insulin-mediated activation of FoxO1, a downstream target of Akt, was suppressed in the gingiva of VEIRKO and high-fat diet (HFD)-fed mice, hyperglycemia-treated ECs, and primary ECs from VEIRKO. Further analysis using ECs transfected with intact and mutated FoxO1, with mutations at 3 insulin-mediated phosphorylation sites (T24A, S256D, S316A), suggested that insulin-mediated regulation of VCAM1 expression and cellular adhesion of ECs with leukocytes was attenuated by mutated FoxO1 overexpression. These results suggest that insulin resistance in ECs may contribute to the progression of periodontitis via dysregulated VCAM1 expression and cellular adhesion with leukocytes, resulting from reduced activation of the PI3K/Akt/FoxO1 axis.

Impacts of heavy metal exposure on the prostate of murine models: Mechanisms of toxicity

Heavy metals are elements found into the environment mainly due to anthropogenic activities. Naturally occurring and higher released doses cause disorders in the prostate, which depends on appropriate hormonal regulation, and exposure to heavy metals may impair prostate homeostasis. The current work highlighted the main mechanisms of toxicity of different environmental heavy metal contaminants, such as aluminum, arsenic, cadmium, chromium, lead, mercury, and nickel, and their impacts found in the prostate morphophysiology of murine models. The repercussions triggered by heavy metals on the prostate include hormonal imbalance and oxidative damage, leading to morphological alterations, which can vary according to the chemical properties of each element, exposure time and concentration, and age. The information of altered biological pathways and its impacts on the prostate of exposed murines are related to human outcomes being useful in the real context of human exposure.

San-Huang-Yi-Shen capsule ameliorates diabetic nephropathy in mice through inhibiting ferroptosis

Diabetic nephropathy (DN) is one of the main complications of diabetes. However, effective therapy to block or slow down the progression of DN is still lacking. San-Huang-Yi-Shen capsule (SHYS) has been shown to significantly improve renal function and delay the progression of DN. However, the mechanism of SHYS on DN is still unclear. In this study, we established a mouse model of DN. Then, we investigated the anti-ferroptotic effects of SHYS including the reduction of iron overload and the activation of cystine/GSH/GPX4 axis. Finally, we used a GPX4 inhibitor (RSL3) and ferroptosis inhibitor (ferrostatin-1) to determine whether SHYS ameliorates DN through inhibiting ferroptosis. The results showed that SHYS treatment was effective for mice with DN in terms of improving renal function, and reducing inflammation and oxidative stress. Besides, SHYS treatment reduced iron overload and upregulated the expression of cystine/GSH/GPX4 axis-related factors in kidney. Moreover, SHYS exhibited similar therapeutic effect on DN as ferrostatin-1, RSL3 could abolish the therapeutic and anti- ferroptotic effects of SHYS on DN. In conclusion, SHYS can be used to treat mice with DN. Furthermore, SHYS could inhibit ferroptosis in DN through reducing iron overload and upregulating the expression of cystine/GSH/GPX4 axis.

Physical activity in a swimming pool attenuates memory impairment by reducing glutamate and inflammatory cytokines and increasing BDNF in the brain of mice with type 2 diabetes

Type 2 diabetes is a risk factor for the development of cognitive impairment. Increasing evidence suggests that regular exercise is beneficial for the treatment of clinical symptoms in diabetic patients. The current study aimed to evaluate whether increasing physical activity through swimming training can reduce memory impairment in an animal model of type 2 diabetes. Diabetes and non-diabetes mice underwent swimming training for four weeks, and then working, spatial, and recognition memory were evaluated using three behavioral tests. Body weight, glucose, and insulin resistance were monitored. We also measured inflammatory cytokines (interleukin (IL)- 6, IL-1β, and tumor-necrosis-factor (TNF)-α), an anti-inflammatory cytokine (IL-10), and brain-derived-neurotrophic-factor (BDNF), and glutamate levels in the hippocampus or prefrontal cortex of mice. The findings showed that diabetes increased body weight, glucose, and insulin resistance, impaired working, spatial and recognition memory, increased levels of IL-6, IL-1β, TNF-α, and glutamate levels, and decreased BDNF in the hippocampus of diabetic mice. While higher physical activity was associated with reduced body weight, glucose, and insulin resistance, attenuated memory impairment, IL-6, IL-1β, TNF-α, and glutamate, and increased BDNF levels in the hippocampus and prefrontal cortex of diabetic mice. This study shows that swimming training can normalize body weight and glucose-insulin axis and reduce inflammation and glutamate in the hippocampus and enhance the neurotrophic system in both the hippocampus and prefrontal cortex of diabetic mice. This study also suggests that higher physical activity through swimming training can improve cognitive impairment in a mouse model of type 2 diabetes.

Antidiabetic activity of Tartary buckwheat protein-derived peptide AFYRW and its effects on protein glycosylation of pancreas in mice

Diabetes Mellitus (DM) is one of the most important public health problems, and new antidiabetic drugs with fewer side effects are urgently needed. Here, we measured the antidiabetic effects of an antioxidant peptide (Ala-Phe-Tyr-Arg-Trp, AFYRW) from Tartary Buckwheat Albumin (TBA) in a high-fat diet/streptozotocin (HFD/STZ)-induced diabetic mouse model. The data showed that AFYRW suppressed hepatocyte steatosis and triglycerides while ameliorating insulin resistance in mice. Successively, the influence of AFYRW on aberrant protein glycosylation in diabetic mice was further investigated by lectin microarrays. The results suggested AFYRW could restore the expression of GalNAc, GalNAcα1-3Gal and GalNAcα1-3Galβ1-3/4Glc recognized by PTL-I, Siaα2-3Galβ1-4Glc(NAc)/Glc, Siaα2-3Gal, Siaα2-3 and Siaα2-3GalNAc recognized by MAL-II, terminating in GalNAcα/β1-3/6Gal recognized by WFA and αGalNAc, αGal, anti-A and B recognized by GSI-I to normal levels in the pancreas of HFD-STZ-induced diabetic mice. This work may provide new targets for the future discovery of potential biomarkers to evaluate the efficacy of food-derived antidiabetic drugs based on precise alterations of glycopatterns in DM.

A tetramethylpyrazine-loaded hyaluronic acid-based hydrogel modulates macrophage polarization for promoting wound recovery in diabetic mice

The failure of wound healing often causes lower limb disability and amputation of diabetic patients. Current strategies for diabetic wound management often fail to achieve the expected outcomes, and emerging alternatives are urgently needed. Recent advances in the identification of active compounds from traditional herbal medicines provide promising therapeutics for tissue repair and regeneration. In this study, the pro-healing effects of tetramethylpyrazine (TMP, a natural alkaloid found in Ligusticum chuanxiong Hort) for diabetic wounds were for the first time demonstrated. The cutaneous healing was mainly achieved by TMP-mediated macrophage polarization from pro-inflammatory to pro-healing phenotype. In addition, the topical administration of TMP was facilitated by the hyaluronic acid (HA) hydrogel for promoting the full-thickness wounds in the experimental diabetic mice. Consequently, TMP-loaded HA hydrogel (TMP-HA) profoundly accelerated the wound closure in comparison with TMP-loaded INTRASITE Gel (it is a commercial hydrogel), which was evident with the inflammation mitigation, the angiogenesis enhancement, and the collagen deposition. Our work reveals the macrophage-modulatory function of TMP for diabetic wound healing and demonstrates great potential of TMP-HA for clinical application.

Preptin Deficiency Does Not Protect against High-Fat Diet-Induced Metabolic Dysfunction or Bone Loss in Mice

Preptin is derived from the cleavage of the E-peptide of pro-insulin-like growth factor (IGF)-II and is an insulin secretagogue. Observational studies have linked elevated circulating preptin to metabolic dysfunction in humans; however, a causal role for preptin in metabolic dysfunction has not been established. Additionally, preptin can promote osteoblast proliferation and differentiation, suggesting a link with skeletal health. We previously described a global preptin knockout (KO) model. In this study, we sought to uncover the impact of preptin KO in mice on the response to a moderately high-fat diet (HFD) and low-fat diet (LFD). HFD groups had higher weight and fat mass gain, lower trabecular and cortical bone volume and fracture load, and higher liver triglycerides. In males, preptin deficiency led to lower blood glucose than wild-type (WT) mice under LFD conditions. This was accompanied by differences in bone microarchitecture, including lower trabecular bone volume fraction, trabecular number, and lower cortical thickness. These differences were absent in female mice, although KO females had a HFD-driven increase in fat mass and liver triglycerides that was absent in WT mice. Female WT mice had increased glucose-stimulated insulin secretion under HFD conditions that was absent in female KO mice. Overall, preptin may have a detrimental impact on metabolism and a positive impact on bone health in male mice and may protect against liver fat storage in females while enabling islet compensation under HFD conditions. When we consider that serum preptin levels are elevated in humans of both sexes in pathological states in which insulin levels are elevated, the impact of preptin on comorbidity risk needs to be better understood. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Lipid droplet-associated lncRNA LIPTER preserves cardiac lipid metabolism

Lipid droplets (LDs) are cellular organelles critical for lipid homeostasis, with intramyocyte LD accumulation implicated in metabolic disorder-associated heart diseases. Here we identify a human long non-coding RNA, Lipid-Droplet Transporter (LIPTER), essential for LD transport in human cardiomyocytes. LIPTER binds phosphatidic acid and phosphatidylinositol 4-phosphate on LD surface membranes and the MYH10 protein, connecting LDs to the MYH10-ACTIN cytoskeleton and facilitating LD transport. LIPTER and MYH10 deficiencies impair LD trafficking, mitochondrial function and survival of human induced pluripotent stem cell-derived cardiomyocytes. Conditional Myh10 deletion in mouse cardiomyocytes leads to LD accumulation, reduced fatty acid oxidation and compromised cardiac function. We identify NKX2.5 as the primary regulator of cardiomyocyte-specific LIPTER transcription. Notably, LIPTER transgenic expression mitigates cardiac lipotoxicity, preserves cardiac function and alleviates cardiomyopathies in high-fat-diet-fed and Leprdb/db mice. Our findings unveil a molecular connector role of LIPTER in intramyocyte LD transport, crucial for lipid metabolism of the human heart, and hold significant clinical implications for treating metabolic syndrome-associated heart diseases.

Zhx2 maintains islet β-cell mass and function by transcriptionally regulating Pax6

Emerging evidence shows that pancreatic β-cell function and quality are key determinants in the progression of type 2 diabetes (T2D). The transcription factor zinc finger homeobox 2 (Zhx2) is involved in proliferation and development of multiple cells. However, the exact role of Zhx2 in β-cells and T2D remains completely unknown. Here, we report that Zhx2 orchestrates β-cell mass and function by regulating paired box protein pax-6 (Pax6). We found that β-cell-specific knockout Zhx2 (Zhx2BKO) mice showed a decrease in β-cell proliferation and glucose homeostasis. Under prediabetic and diabetic conditions, we discovered glucose intolerance in both Zhx2BKO-HFD mice and Zhx2BKO-db/db mice, with reduced β-cell mass and insulin secretion. Mechanistically, we demonstrated that Zhx2 targeted the Pax6 promoter region (-1740∼-1563; -862∼-559; -251∼+75), enhanced promoter activity. Overall, Zhx2 maintains β-cell function by transcriptionally regulating Pax6, which provides a therapeutic target for diabetes intervention.

Role of Bmal1 in Type 2 Diabetes Mellitus-Related Glycolipid Metabolic Disorder and Neuropsychiatric Injury: Involved in the Regulation of Synaptic Plasticity and Circadian Rhythms

Increasing data suggest a crucial role of circadian rhythm in regulating metabolic and neurological diseases, and Bmal1 is regarded as a key regulator of circadian transcription. The aim of this study is to investigate the role of Bmal1 in the disruption of circadian rhythm and neuropsychiatric injuries in type 2 diabetes mellitus (T2DM). A T2DM model was induced by the combination of high-fat-diet (HFD) and streptozotocin (STZ) in vivo or HT-22 cells challenged with palmitic-acid (PA) in vitro. The glucolipid metabolism indicators, behavioral performance, and expression of synaptic plasticity proteins and circadian rhythm-related proteins were detected. These changes were also observed after interference of Bmal1 expression via overexpressed plasmid or small interfering RNAs in vitro. The results showed that HFD/STZ could induce T2DM-like glycolipid metabolic turmoil and abnormal neuropsychiatric behaviors in mice, as indicated by the increased concentrations of fasting blood-glucose (FBG), HbA1c and lipids, the impaired glucose tolerance, and the decreased preference index of novel object or novel arm in the novel object recognition test (NOR) and Y-maze test (Y-maze). Consistently, the protein expression of synaptic plasticity proteins and circadian rhythm-related proteins and the positive fluorescence intensity of MT1B and Bmal1 were decreased in the hippocampus of HFD/STZ-induced mice or PA-challenged HT-22 cells. Furthermore, overexpression of Bmal1 could improve the PA-induced lipid metabolic dysfunction and increase the decreased expressions of synaptic plasticity proteins and circadian rhythm-related proteins, and vice versa. These results suggested a crucial role of Bmal1 in T2DM-related glycolipid metabolic disorder and neuropsychiatric injury, which mechanism might be involved in the regulation of synaptic plasticity and circadian rhythms.