Diet-induced Mice Research Articles

Analysis of Liver Function in Retinoic Acid Receptor Gamma Liver Specific Knockout Mice

Non-Alcoholic Fatty Liver Disease (NAFLD) affects about one-third of the United States population and continues to grow in prevalence. Characterizing a spectrum of disease, NAFLD can range from simple steatosis to fibrosis and cirrhosis, which later can progress to hepatocellular carcinoma. Treatment options for this disease are currently limited to changing diet and exercise. Research efforts have been geared towards identifying and investigating potential targets for treatment of those with NAFLD. Via binding to retinoic acid, the biologically active metabolite of the micronutrient vitamin A (retinol), retinoic acid receptors (RARs α, β. γ) are known to regulate energy metabolism, and it has been shown that NAFLD leads to an altered/impaired state of vitamin A metabolism in the liver. In addition, our laboratory demonstrated that stimulation of the RA signaling pathway reduced hepatic steatosis in a High Fat Diet-induced NAFLD mouse model. Since RARγ is highly expressed in the liver, we are investigating the role of RARγ in NAFLD by characterizing the functional and molecular phenotypes of a murine liver-specific RARγ knockout. To date we have found that there is no difference in the vitamin A levels in the livers of these RARγ knockout mice. Through the characterization of this murine transgenic model, we will be able to determine the role of RARy in the liver, as well as to test new therapeutics that act via this receptor to potentially prevent/treat NAFLD.

Suppression of E4BP4 SUMOylation sensitize mice to HFD‐induced fatty liver disease by promoting lipid droplet formation

Background As the most common chronic liver disease, non-alcoholic fatty liver disease (NAFLD) affects 10-30% of the general population. Characterized by excessive lipid droplet formation in hepatocytes, fatty liver may progress to nonalcoholic steatohepatitis (NASH), eventually leading to cirrhosis and liver failure. Currently, there have been no effective therapeutic or preventive measures for NAFLD. Thus, there is an urgent need to identify hepatic mediators that promote lipid droplet accumulation as well as the underlying molecular mechanisms in the liver during the pathogenesis of NAFLD. We previously reported that E4 promoter-binding protein 4 (E4BP4) is an insulin-induced stabilizer of the lipogenic factor SREBP-1c and promotes the SREBP-1c-mediated lipogenesis in hepatocytes. Our most recent mass spectrometry data revealed that E4BP4 may undergo SUMOylation, a reversible post-translational modification that was shown to regulate E4BP4-dependent NK cell development. In this study, we set out to determine how hepatic E4BP4 regulates lipid droplet formation and liver steatosis a high-fat diet-induced NAFLD mouse model and investigate how E4BP4 SUMOylation impacts the process. Results Compared with E4bp4flox/flox mice, E4bp4 liver-specific KO (E4bp4-LKO) mice exhibit decreased lipid accumulation in the liver despite similar body weight after 12 weeks of high-fat diet feeding. Our microarray analysis showed a reduction in the expression of lipid droplet biding genes such as Cidea, Cidec (Fsp27), Plin4 in the liver of E4bp4-LKO mice. Restoring E4bp4 expression in E4bp4-LKO primary hepatocytes was sufficient to induce lipid droplet formation and Fsp27β expression, while overexpression of Fsp27β increased lipid droplets and triglycerides in E4bp4-LKO primary mouse hepatocytes and promoted lipid accumulation HFD-fed E4bp4-LKO mice. Meanwhile, we generated an E4BP4 mutant, namely E4BP4-5KR, which contains five lysine to arginine (5KR) substitutions in the five SUMOylation motifs. Our in vitro SUMOylation assay confirmed the SUMOylation of E4BP4-WT but not E4BP4-5KR mutant in the presence of E1/2, SUMO2/3, and ATP. We detected more lipid droplet formation in hepa1 cells transfected with E4bp4-5KR vs. E4bp4-WT. Lastly, the abundance of SUMOylated E4BP4 was reduced in the liver of high-fat diet-fed mice vs. regular chow-fed mice. Conclusion All together, our data demonstrated that E4bp4 drives lipid droplet formation and live steatosis in high-fat diet-fed mice likely through its regulation of lipid-droplet binding genes. Our study also highlights the critical role of deSUMOylation of hepatic E4BP4 in promoting NAFLD and suggests that E4BP4 SUMOylation in the liver could be targeted for treating NAFLD.

Myocardial ischemia-reperfusion and diabetes: The crux of animal model choice

Due to the failure of the translation of cardioprotective drugs against myocardial infarction from bench to bedside, revising animal models has become a necessity. Owing to its current growing incidence, type 2 diabetes (T2D) represents one of the main risk factors of co-morbidities in myocardial infarction, yet discrepancies exist between reported animal and human studies. We aimed to compare the impact of diabetes on infarct size after cardiac ischemia-reperfusion in a human cohort of ST elevation myocardial infarction (STEMI) patients with a diet-induced mouse model of T2D, using a high-fat high-sucrose diet for 16 weeks (HFHSD). Infarct size was evaluated by MRI in a cohort of 250 STEMI patients after primary percutaneous intervention. For mouse study, T2D was induced by 16 weeks of HFHSD versus a standard diet (SD) then in vivo 45 mins ischemia followed by 24 hrs of reperfusion were performed to compare myocardial infarct size. To mimic the diabetic medication regimen, 6 weeks of oral gavage with Metformin was performed in the HFHSD group: cell death upon in vitro 70 min hypoxia-2 h reoxygenation (H/R) on isolated cardiomyocytes was analysed by propidium-iodide staining. A small fraction (< 14%) of STEMI patients were diabetic and did not show a bigger infarct size when compared to non-diabetic ones. HFHSD mice had bigger infarct size compared to SD (HFHSD 47.8 [43.5, 49.0] vs. SD 37.3 [33.5, 43.6] %, n = 8–9/group, P < 0.05). Metformin treatment reduced cell death after H/R in the HFHSD cardiomyocytes, to a similar extent as in SD cells. Our data highlight that anti-diabetic medications may have a protective effect, thus they should be included in the pre-clinical studies of cardioprotective approaches in diabetic models. However, the relatively low number of diabetic patients in the STEMI population should also lead us to think about the inclusion of other risk factors in our animal models, notably aging.

Investigation of an ALDH1A1-specific inhibitor for suppression of weight gain in a diet-induced mouse model of obesity.

Background:Retinoic acid (RA) controls diverse physiological functions including weight regulation and energy metabolism. It has been reported that mice lacking ALDH1A1, one of the aldehyde dehydrogenases (ALDH) that synthesize RA, are healthy and resistant to weight gain, raising the possibility that inhibiting this enzyme might treat obesity. We previously demonstrated that treatment with a pan-ALDH1A enzyme inhibitor, WIN18446, suppressed weight gain in mice fed a high fat diet (HFD), but caused increased hepatic lipidosis and reversible male infertility.Methods:A series of piperazine compounds that inhibited ALDH1A1 were identified and their inhibitory activity was characterized in vitro using purified recombinant enzymes and cell-based assay systems. One potent compound, FSI-TN42 (N42) was examined for its oral bioavailability and pharmacodynamic effects. In addition, its effect on weight gain was investigated by daily oral administration to C57BL/6 male mice receiving a HFD, and compared with mice receiving WIN18446 or vehicle alone (n=6/group, 200 mg compound/kg body weight) for 5 weeks. Body weights were measured weekly, and a glucose tolerance test was performed after 4 weeks of treatment. Tissues were collected to determine changes in adipose weight, hepatic lipidosis, retinoid metabolism, and expression of genes associated with RA and lipid metabolism.Results:N42 irreversibly binds and inhibits ALDH1A1 in vitro with a low nM IC50 and 800-fold specificity for ALDH1A1 compared to ALDH1A2. Daily oral administration of N42 significantly suppressed weight gain (P<0.05) and reduced visceral adiposity (p<0.05) in mice fed a HFD without the hepatic lipidosis observed with WIN18446 treatment.Conclusions:We developed a potent and specific inhibitor of ALDH1A1 that suppressed weight gain in mice fed a HFD. These findings demonstrate that inhibition of ALDH1A1 is a feasible target for drug development to treat and/or prevent obesity.

Enhanced Arterial Stiffening in Obese Mice with Smooth Muscle‐Specific Overexpression of Smpd1 gene

Arterial stiffening is a risk factor for cardiovascular morbidity. Recent studies have shown that lysosomal ceramide contributed to the phenotype change and exosome secretion in arterial smooth muscle cells (SMCs) during the development of arterial medial calcification. The present study was designed to investigate whether lysosomal ceramide produced from acid sphingomyelinase (ASM) contributes to arterial stiffening in diet-induced obesity. It was found that in a diet-induced mouse model of obesity by feeding mice high fat diet (HF), arterial stiffness as measured in vivo using a high-resolution Doppler ultrasound imaging was significantly enhanced in mice with a transgene of ASM (its mouse gene code is Smpd1), namely, Smpd1trg/SMCre mice as compared to their wild type littermates (WT/WT). This obesity-induced enhancement of arterial stiffening was further strengthened by administration of high sucrose water (30%). Smpd1trg/SMCre mice on the HF diet or HF diet with high sucrose water (HFHS) showed significantly increased glucose levels as compared to WT/WT without significant difference in the body weight. By Masson Trichrome staining, we observed markedly increased collagen deposition in Smpd1trg/SMCre mice treated with HF diet, which was further increased in HFHS group of mice compared to WT/WT. Furthermore, Smpd1trg/SMCre mice treated with HF or HFHS were shown to have significant increase in the expression of exosome markers such as CD63 and annexin-II (AnX2) in the coronary arterial wall as compared to WT/WT mice. In the plasma of Smpd1trg/SMCre mice, the number of exosomes also significantly increased as compared to WT/WT mice either on normal, HF or HFHS diet. All these data indicate that a transgene of ASM in Smpd1trg/SMCre mice leads to increased glucose and collagen levels associated with augmented exosomes secretion that may contribute to the enhancement of arterial stiffening during diet-induced obesity.

Integrative study of diet-induced mouse models of NAFLD identifies PPARα as a sexually dimorphic drug target

ObjectiveWe evaluated the influence of sex on the pathophysiology of non-alcoholic fatty liver disease (NAFLD). We investigated diet-induced phenotypic responses to define sex-specific regulation between healthy liver and NAFLD to...

Anti-Inflammatory, Anti-Oxidant, and Anti-Lipaemic Effects of Daily Dietary Coenzyme-Q10 Supplement in a Mouse Model of Metabolic Syndrome.

The dietary model of metabolic syndrome has continued to aid our understanding of its pathogenesis and possible management interventions. However, despite progress in research, therapy continues to be challenging for humans; hence, the search for newer treatment and prevention options continues. The objective of this study was to evaluate the impact of dietary CQ10 supplementation on metabolic, oxidative, and inflammatory markers in a diet-induced mouse model of metabolic syndrome. Mouse groups were fed a Standard Diet (SD), High-Fat High-Sugar (HFHS) diet, and SD or HFHS diet (with incorporated CQ10) at 60 and 120 mg/kg of feed. At the completion of the study (8 weeks), blood glucose levels, Superoxide Dismutase (SOD) activity, plasma insulin, leptin, adiponectin, TNF-α, IL-10, serum lipid profile, and Lipid Peroxidation (LPO) levels were assessed. The liver was either homogenised for the assessment of antioxidant status or processed for general histology. Dietary CQ10 mitigated HFHS diet-induced weight gain, decreased glucose, insulin, and leptin levels, and increased adiponectin levels in mice. Coenzyme-Q10 improved the antioxidant status of the liver and blood in HFHS diet-fed mice while also decreasing lipid peroxidation. Lipid profile improved, level of TNF-α decreased, and IL-10 increased following CQ10 diet. A mitigation of HFHS diet-induced alteration in liver morphology was also observed with CQ10. Dietary CQ10 supplementation mitigates HFHS diet-induced changes in mice, possibly through its anti-oxidant, anti-lipaemic, and anti-inflammatory potential.

Lactobacillus Sps in Reducing the Risk of Diabetes in High-Fat Diet-Induced Diabetic Mice by Modulating the Gut Microbiome and Inhibiting Key Digestive Enzymes Associated with Diabetes.

Simple SummaryType 2 diabetes (T2D) is increasingly spreading across the globe. The disease is linked to a disruption of gut microbiome. Probiotics are essential gut microbiota modulators proven to restore microbiota changes, thereby conferring health to its host. This study aimed to use probiotics (lactobacilli) and their metabolites as natural anti-diabetic therapy through the modulation of gut microbiota and inhibit diabetes-causing enzymes. Lactobacillus-treated high-fat diet mice showed lower blood glucose levels and body weight. Interestingly, our study also proved that the lactobacilli altered gut microbiota composition by suppressing opportunistic bacteria that are highly associated with metabolic diseases. Our findings substantiate the use of probiotics as natural anti-diabetic therapeutics.Obesity caused by a high-fat diet (HFD) affects gut microbiota linked to the risk of type-2 diabetes (T2D). This study evaluates live cells and ethanolic extract (SEL) of Lactobacillus sakei Probio65 and Lactobacillus plantarum Probio-093 as natural anti-diabetic compounds. In-vitro anti-diabetic effects were determined based on the inhibition of α-glucosidase and α-amylase enzymes. The SEL of Probio65 and Probio-093 significantly retarded α-glucosidase and α-amylase enzymes (p < 0.05). Live Probio65 and Probio-093 inhibited α-glucosidase and α-amylase, respectively (p < 0.05). In mice fed with a 45% kcal high-fat diet (HFD), the SEL and live cells of both strains reduced body weight significantly compared to HFD control (p < 0.05). Probio-093 also improved blood glucose level compared to control (p < 0.05). The gut microbiota modulatory effects of lactobacilli on HFD-induced diabetic mice were analyzed with qPCR method. The SEL and live cells of both strains reduced phyla Deferribacteres compared to HFD control (p < 0.05). The SEL and live cells of Probio-093 promoted more Actinobacteria (phyla), Bifidobacterium, and Prevotella (genus) compared to control (p < 0.05). Both strains exerted metabolic-modulatory effects, with strain Probio-093 showing more prominent alteration in gut microbiota, substantiating the role of probiotics in gut microbiome modulations and anti-diabetic effect. Both lactobacilli are potential candidates to lessen obesity-linked T2D.

Effect of fermented bee pollen on metabolic syndrome in high-fat diet-induced mice

Bee pollen has potential in preventing metabolic syndrome (MetS). The present study aimed to investigate the effect of yeast-fermented wall-broken bee pollen (YB) intervention on ICR mice with MetS induced with a high-fat (HF) diet. After YB intervention in mice for 16 weeks, the effect on alleviating MetS was evaluated based on MetS serum parameters, hepatic oxidant status markers and gut microbial populations. The results of animal experiment showed that YB intervention attenuated MetS. Based on multivariate statistical analysis results, YB treatment significantly increased glutathione S-transferase (GST) and catalase (CAT) activities and decreased the malondialdehyde (MDA) level in the liver. Further investigation showed that YB restored the Nrf-2-Keap-1 pathway to alleviate oxidative stress. Additionally, gut microbial community analysis revealed that YB restored the increase in the Firmicutes to Bacteroidetes (F/B) ratio (6.94 for the HF group and 3.74 for HF+YB group) and improved Lactobacillus and Lactococcus abundance induced by the HF diet. Overall, YB improved function and prevented MetS by modulating the gut microbiota and alleviating oxidative stress.

RYGB Is More Effective than VSG at Protecting Mice from Prolonged High-Fat Diet Exposure: An Occasion to Roll Up Our Sleeves?

Understanding the effects of Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) on adipose tissue physiology is important for the treatment of obesity-related metabolic disorders. By using robust mouse models of bariatric surgery that closely resemble those performed in humans, we can compare the effects of RYGB and VSG on adipose physiology in the absence of post-operative confounds such as diet and lifestyle changes. RYGB and VSG were compared using a diet-induced mouse model of obesity. High-fat diet (HFD) was administered post-operatively and changes to white and brown adipose tissue were evaluated, along with alterations to weight, glucose homeostasis, dyslipidemia, and insulin sensitivity. After prolonged exposure to high-fat diet post-operatively, RYGB was effective in achieving sustained weight loss, while VSG unexpectedly accelerated weight gain rates. The resolution of obesity-related comorbidities such as glucose and insulin intolerance, dyslipidemia, and insulin sensitivity was improved after RYGB, but not for VSG. In RYGB, there were improvements to the function and health of white adipose tissue, enhanced brown adipose metabolism, and the browning of subcutaneous white adipose tissue, with no comparable changes seen for these factors after VSG. Some markers of systemic inflammation improved after both RYGB and VSG. There are significantly different effects between RYGB and VSG when HFD is administered post-operatively and robust mouse models of bariatric surgery are used. RYGB resulted in lasting physiological and metabolic changes but VSG showed little difference from that of its sham-operated, DIO counterpart.

Validation of Antiobesity Effects of Black Soybean Seed Coat Powder Suitable as a Food Material: Comparisons with Conventional Yellow Soybean Seed Coat Powder.

In this study, we fed obese model mice black soybean seed coat powder (BSCP) and evaluated the antiobesity effects. As a control, normal yellow soybean seed coat powder (YSCP) was used. C57BL/6J, a high-fat diet-induced obesity model mouse, was fed a high-fat diet containing BSCP or YSCP (20% fat) to induce obesity. The results showed that in the BSCP group, it caused significant suppression of body weight gain and suppression of white adipose tissue weight compared with the YSCP group. Moreover, it significantly decreased serum leptin levels, which correlated with visceral fat mass, and increased antidiabetic adipocytokine and adiponectin levels. Therefore, this suggests the pigmented components contained in BSCP have an antiobesity effect in obese model mice. It is suggested that this material, which can be prepared without extraction with an organic solvent and is suitable for use as a food material, could be a functional food material with a practicable antiobesity effect.

Tracking Acoustic and Electrophysiological Changes Associated with CKD-induced Cardiac and Valvular Remodeling in a Mouse Model

Objective: Patients with chronic kidney disease (CKD) are at a higher risk of developing heart and valvular diseases than the general population. Non-invasive screening methods are needed to identify cardiovascular abnormalities in this population. In this study, we use a diet-induced CKD mouse to study AV and cardiac remodeling. We hypothesize that structural differences in AV and cardiac remodeling occur in CKD mice, and can be identified through phonocardiogram (PCG) and electrocardiogram (ECG) signals. Methods: Eight-week old C57BL/6J mice were assigned to the following groups: 1) control group, fed a normal chow diet for 12 weeks, and 2) CKD group, fed a chow containing 0.2% adenine, with normal (0.6%) phosphorus for 6 weeks to induce CKD, and 3) CKD+high phosphate (HP) group, fed CKD inducing diet for 6 weeks, and then fed for 6 weeks with a 0.2% adenine/1.8% phosphorus diet to induce cardiovascular calcification. PCG and ECG signals were recorded weekly and echocardiogram parameters were recorded at the experimental end-point. Results: The HP diet induced aortic valve calcification in the CKD+HP group. CKD and CKD+HP group had increased end-diastolic volume, which is indicative of left ventricular hypertrophy. Changes in ECG parameters indicate that CKD groups have delayed cardiac repolarization time, an early ECG marker associated with arrhythmias. PCG signals indicate the presence of a systolic and diastolic murmur in the CKD+HP group, a characteristic of both valve disease and cardiac dysfunction. Conclusions: We demonstrate that the diet-induced CKD mouse model can be used to study valve and cardiac remodeling, and ECG and PCG signals can noninvasively track valve and cardiac changes. Future studies will determine the adequacy of using these signals to predict cardiovascular diseases.

Therapeutic Effect of Endothelin-Converting Enzyme Inhibitor on Chronic Kidney Disease through the Inhibition of Endoplasmic Reticulum Stress and the NLRP3 Inflammasome.

Chronic inflammation and oxidative stress significantly contribute to the development and progression of chronic kidney disease (CKD). The NOD-like receptor family pyrin containing domain-3 (NLRP3) inflammasome plays a key role in the inflammatory response. The renal endothelin (ET) system is activated in all cases of CKD. Furthermore, ET-1 promotes renal cellular injury, inflammation, fibrosis and proteinuria. Endothelin-converting enzymes (ECEs) facilitate the final processing step of ET synthesis. However, the roles of ECEs in CKD are not clear. In this study, we investigated the effects of ETs and ECEs on kidney cells. We found that ET-1 and ET-2 expression was significantly upregulated in the renal tissues of CKD patients. ET-1 and ET-2 showed no cytotoxicity on human kidney tubular epithelial cells. However, ET-1 and ET-2 caused endoplasmic reticulum (ER) stress and NLRP3 inflammasome activation in tubular epithelial cells. The ECE inhibitor phosphoramidon induced autophagy. Furthermore, phosphoramidon inhibited ER stress and the NLRP3 inflammasome in tubular epithelial cells. In an adenine diet-induced CKD mouse model, phosphoramidon attenuated the progression of CKD by regulating autophagy, the NLRP3 inflammasome and ER stress. In summary, these findings showed a new strategy to delay CKD progression by inhibiting ECEs through autophagy activation and restraining ER stress and the NLRP3 inflammasome.

First person – Sarah Elzinga

ABSTRACTFirst Person is a series of interviews with the first authors of a selection of papers published in Disease Models & Mechanisms, helping early-career researchers promote themselves alongside their papers. Sarah Elzinga is first author on ‘Sex differences in insulin resistance, but not peripheral neuropathy, in a diet-induced prediabetes mouse model’, published in DMM. Sarah is a postdoc in the lab of Eva Feldman at the University of Michigan, Ann Arbor, MI, USA, investigating immune-mediated mechanisms that promote neurodegeneration in obesity, metabolic syndrome, prediabetes and type 2 diabetes.

Sex differences in insulin resistance, but not peripheral neuropathy, in a diet-induced prediabetes mouse model.

ABSTRACTPeripheral neuropathy (PN) is a common complication of prediabetes and diabetes and is an increasing problem worldwide. Existing PN treatments rely solely on glycemic control, which is effective in type 1 but not type 2 diabetes. Sex differences in response to anti-diabetic drugs further complicate the identification of effective PN therapies. Preclinical research has been primarily carried out in males, highlighting the need for increased sex consideration in PN models. We previously reported PN sex dimorphism in obese leptin-deficient ob/ob mice. This genetic model is inherently limited, however, owing to leptin's role in metabolism. Therefore, the current study goal was to examine PN and insulin resistance in male and female C57BL6/J mice fed a high-fat diet (HFD), an established murine model of human prediabetes lacking genetic mutations. HFD mice of both sexes underwent longitudinal phenotyping and exhibited expected metabolic and PN dysfunction compared to standard diet (SD)-fed animals. Hindpaw thermal latencies to heat were shorter in HFD females versus HFD males, as well as SD females versus males. Compared to HFD males, female HFD mice exhibited delayed insulin resistance, yet still developed the same trajectory of nerve conduction deficits and intraepidermal nerve fiber density loss. Subtle differences in adipokine levels were also noted by sex and obesity status. Collectively, our results indicate that although females retain early insulin sensitivity upon HFD challenge, this does not protect them from developing the same degree of PN as their male counterparts.This article has an associated First Person interview with the first author of the paper.

Isotschimgine alleviates nonalcoholic steatohepatitis and fibrosis via FXR agonism in mice.

Farnesoid X receptor (FXR) agonist obeticholic acid (OCA) has emerged as a potential therapy for nonalcoholic fatty liver disease (NAFLD). However, the side effects of OCA may limit its application in clinics. We identified previously that isotschimgine (ITG) is a non-steroidal FXR selective agonist and has potent therapeutic effects on NAFLD in mice. Here, we aimed to evaluate the therapeutic effects of ITG on nonalcoholic steatohepatitis (NASH) and fibrosis in mice. We used methionine and choline deficient (MCD) diet-induced NASH mice, bile duct ligation (BDL), and carbon tetrachloride (CCl4 )-treated hepatic fibrosis mice to investigate the effects of ITG on NASH, fibrosis, and cholestatic liver injury. Our results showed that ITG improved steatosis and inflammation in the liver of MCD diet-fed mice, as well as alleviated fibrosis and inflammation in the liver of CCl4 -treated mice. Furthermore, ITG attenuated serum bile acid levels, and reduced vacuolization, inflammatory infiltration, hepatic parenchymal necrosis, and collagen accumulation in the liver of BDL mice. Mechanistically, ITG increased the expression of FXR target genes. These data suggest that ITG is an FXR agonist and may be developed as a novel therapy for NASH, hepatic fibrosis, or primary biliary cholangitis.

Myocardial Ischemia-Reperfusion and Diabetes: Lessons Learned From Bedside to Bench.

In front of the failure to translate from bench to bedside cardioprotective drugs against myocardial ischemia-reperfusion, research scientists are currently revising their animal models. Owing to its growing incidence nowadays, type 2 diabetes (T2D) represents one of the main risk factors of co-morbidities in myocardial infarction. However, discrepancies exist between reported animal and human studies. Our aim was here to compare the impact of diabetes on cell death after cardiac ischemia-reperfusion in a human cohort of ST-elevation myocardial infarction (STEMI) patients with a diet-induced mouse model of T2D, using a high-fat high-sucrose diet for 16 weeks (HFHSD). Interestingly, a small fraction (<14%) of patients undergoing a myocardial infarct were diabetic, but treated, and did not show a bigger infarct size when compared to non-diabetic patients. On the contrary, HFHSD mice displayed an increased infarct size after an in vivo cardiac ischemia-reperfusion, together with an increased cell death after an in vitro hypoxia-reoxygenation on isolated cardiomyocytes. To mimic the diabetic patients' medication profile, 6 weeks of oral gavage with Metformin was performed in the HFHSD mouse group. Metformin treatment of the HFHSD mice led to a similar extent of lower cell death after hypoxia-reoxygenation as in the standard diet group, compared to the HFHSD cardiomyocytes. Altogether, our data highlight that due to their potential protective effect, anti-diabetic medications should be included in pre-clinical study of cardioprotective approaches. Moreover, since diabetic patients represent only a minor fraction of the STEMI patients, diabetic animal models may not be the most suitable translatable model to humans, unlike aging that appears as a common feature of all infarcted patients.

Obeticholic Acid Inhibits Anxiety via Alleviating Gut Microbiota-Mediated Microglia Accumulation in the Brain of High-Fat High-Sugar Diet Mice.

Anxiety is one of the complications of metabolic disorders (MDs). Obeticholic acid (OCA), the bile acids (BAs) derivative, is a promising agent for improving MDs in association with gut dysbiosis. Yet, its protective effect on MDs-driven anxiety remains unknown. Here, we assessed the serum biochemical parameters and behavioral performance by open field and Morris water maze tests in HFHS diet-induced MDs mice after OCA intervention for nine and 18 weeks. Moreover, antibiotics intervention for microbial depletion was conducted simultaneously. We found that OCA treatment inhibited the initiation and progression of anxiety in HFHS diet-MDs mice via a microbiota–BAs–brain axis: OCA decreased the neuroinflammatory microglia and IL-1β expression in the hippocampus, reversed intestinal barrier dysfunction and serum proinflammatory LPS to a normal level, modified the microbial community, including the known anxiety-related Rikenellaceae and Alistipes, and improved the microbial metabolites especially the increased BAs in feces and circulation. Moreover, the OCA-reversed bile acid taurocholate linked disordered serum lipid metabolites and indole derivatives to anxiety as assessed by network analysis. Additionally, microbial depletion with antibiotics also improved the anxiety, microgliosis and BAs enrichment in the experimental MDs mice. Together, these findings provide microbiota–BAs–brain axis as a novel therapeutic target for MDs-associated neuropsychiatric disorders.

Liraglutide targets the gut microbiota and the intestinal immune system to regulate insulin secretion.

Liraglutide controls type 2 diabetes (T2D) and inflammation. Gut microbiota regulates the immune system and causes at least in part type 2 diabetes. We here evaluated whether liraglutide regulates T2D through both gut microbiota and immunity in dysmetabolic mice. Diet-induced dysmetabolic mice were treated for 14days with intraperitoneal injection of liraglutide (100µg/kg) or with vehicle or Exendin 4 (10µg/kg) as controls. Various metabolic parameters, the intestinal immune cells were characterized and the 16SrDNA gene sequenced from the gut. The causal role of gut microbiota was shown using large spectrum antibiotics and by colonization of germ-free mice with the gut microbiota from treated mice. Besides, the expected metabolic impacts liraglutide treatment induced a specific gut microbiota specific signature when compared to vehicle or Ex4-treated mice. However, liraglutide only increased glucose-induced insulin secretion, reduced the frequency of Th1 lymphocytes, and increased that of TReg in the intestine. These effects were abolished by a concomitant antibiotic treatment. Colonization of germ-free mice with gut microbiota from liraglutide-treated diabetic mice improved glucose-induced insulin secretion and regulated the intestinal immune system differently from what observed in germ-free mice colonized with microbiota from non-treated diabetic mice. Altogether, our result demonstrated first the influence of liraglutide on gut microbiota and the intestinal immune system which could at least in part control glucose-induced insulin secretion.

Carob pod polyphenols suppress the differentiation of adipocytes through posttranscriptional regulation of C/EBPβ.

Obesity is a major risk factor for various chronic diseases such as diabetes, cardiovascular disease, and cancer; hence, there is an urgent need for an effective strategy to prevent this disorder. Currently, the anti-obesity effects of food ingredients are drawing attention. Therefore, we focused on carob, which has high antioxidant capacity and various physiological effects, and examined its anti-obesity effect. Carob is cultivated in the Mediterranean region, and its roasted powder is used as a substitute for cocoa powder. We investigated the effect of carob pod polyphenols (CPPs) on suppressing increases in adipose tissue weight and adipocyte hypertrophy in high fat diet-induced obesity model mice, and the mechanism by which CPPs inhibit the differentiation of 3T3-L1 preadipocytes into adipocytes in vitro. In an in vivo experimental system, we revealed that CPPs significantly suppressed the increase in adipose tissue weight and adipocyte hypertrophy. Moreover, in an in vitro experimental system, CPPs acted at the early stage of differentiation of 3T3-L1 preadipocytes and suppressed cell proliferation because of differentiation induction. They also suppressed the expression of transcription factors involved in adipocyte differentiation, thereby reducing triacylglycerol synthesis ability and triglycerol (TG) accumulation. Notably, CPPs regulated CCAAT/enhancer binding protein (C/EBP)β, which is expressed at the early stage of differentiation, at the posttranscriptional level. These results demonstrate that CPPs suppress the differentiation of adipocytes through the posttranscriptional regulation of C/EBPβ and may serve as an effective anti-obesity compound.