Project description:BACKGROUND:Accumulating evidence indicates that high-fat diet (HFD)-induced metabolic disorders are associated with dysbiosis of the gut microbiota. However, the sex-specific characteristics of the gut microbiota and its association with a sexually dimorphic response to a HFD remain unclear. METHODS:Male and female mice were randomly assigned to receive a chow diet (CD) or HFD for 12 weeks. A group of HFD mice were pretreated with antibiotic cocktails for 4 weeks. Body weight, insulin sensitivity and the levels of serum metabolic parameters (blood glucose and insulin) were evaluated. 16S rRNA gene sequencing was performed to analyze the composition of the gut microbiota. RESULTS:HFD-induced body weight gain (BWG) was higher in male mice than in female mice. While insulin resistance was increased in the HFD group compared to CD group in male mice, there was no difference in insulin resistance among female mice. Antibiotic-pretreatment alleviated HFD-induced insulin resistance in male mice and elevated fasting blood glucose in female mice. The composition of the gut microbiota in male mice was remarkably different from that in female mice independent of diet. A higher abundance of the genera Parabacteroides, Lactobacillus, Bacteroides, and Bifidobacterium was observed in females than inmales. HFD feeding also influenced the structure of the gut microbiota, as it decreased the abundance of short-chain fatty acids-producing bacteria including Roseburia and Lachnospiraceae_NK4A136_group. Alterations in the gut microbiota in response to antibiotics followed by HFD were different between males and females, indicating sex-dependent sensitivity to antibiotics. CONCLUSIONS:We identified that sex had a greater impact on the composition of gut microbiota than environmental factors (HFD and antibiotics). The enrichment of beneficial microbes in female mice may be associated with the resistance of female mice to HFD-induced metabolic disorders, which was weakened by antibiotic pretreatment.
Project description:To study the effects of N-acetylcysteine (NAC, C5H9NO3S) on diet-induced obesity and obesity-related metabolic disorders.Six-week-old male C57BL/6 mice fed a chow or high-fat diet (HFD) were treated with NAC (2 g/L) in drinking water for 11 weeks. Its influences on body weight and food intake were manually measured, and influence on body composition were analyzed by magnetic residence imaging. Glucose meter and ELISA were used to determine serum glucose and insulin levels, as well as lipid content in the liver. The effects of NAC treatment on mRNA levels of genes involved in inflammation, thermogenesis, and lipid metabolism in various tissues were determined by real time PCR.NAC supplementation inhibited the increase of fat mass and the development of obesity when mice were fed an HFD. NAC treatment significantly lowered HFD-induced macrophage infiltration, and enhanced adiponectin gene expression, resulting in reduced hyperglycemia and hyperinsulinemia, and improvement of insulin resistance. NAC oral administration suppressed hepatic lipid accumulation, as evidenced by lower levels of triglyceride and cholesterol in the liver. The beneficial effects are associated with a decrease of hepatic Ppar? and its target gene expression, and an increase in the expression of genes responsible for lipid oxidation and activation of farnesoid X receptor. Furthermore, NAC treatment also stimulates expression of thermogenic genes.These results provide direct proof of the protective potential of NAC against HFD-induced obesity and obesity-associated metabolic disorders.
Project description:Dietary lipids favor the growth of the pathobiont Bilophila wadsworthia, but the relevance of this expansion in metabolic syndrome pathogenesis is poorly understood. Here, we showed that B. wadsworthia synergizes with high fat diet (HFD) to promote higher inflammation, intestinal barrier dysfunction and bile acid dysmetabolism, leading to higher glucose dysmetabolism and hepatic steatosis. Host-microbiota transcriptomics analysis reveal pathways, particularly butanoate metabolism, which may underlie the metabolic effects mediated by B. wadsworthia. Pharmacological suppression of B. wadsworthia-associated inflammation demonstrate the bacterium's intrinsic capacity to induce a negative impact on glycemic control and hepatic function. Administration of the probiotic Lactobacillus rhamnosus CNCM I-3690 limits B. wadsworthia-induced immune and metabolic impairment by limiting its expansion, reducing inflammation and reinforcing intestinal barrier. Our results suggest a new avenue for interventions against western diet-driven inflammatory and metabolic diseases.
Project description:Consumption of a high-fat diet (HFD) is associated with white adipose tissue (WAT) inflammation, which contributes to key components of the metabolic syndrome, including insulin resistance (IR) and hepatic steatosis (HS). To determine the differential effects of exercise training (EX), low-fat diet (LFD), and their combination on WAT inflammation, Balb/cByJ male mice (n=34) were fed an HFD for 12 wks before they were randomized into one of four intervention groups: HFD-EX, LFD-EX, HFD-sedentary (SED), or LFD-SED. EX mice performed 12 wks of exercise training on a motorized treadmill (1h/d, 5d/wk, 12 m/min, 5% grade, approximately 65% VO(2) max), while SED mice remained sedentary in their home cages. WAT gene expression of adipokines was assessed using rt-PCR. IR was measured using HOMA-IR, and HS via hepatic triglyceride content. EX significantly reduced (53%) WAT gene expression of MCP-1, and LFD significantly reduced (50%) WAT gene expression of the macrophage specific marker, F4/80 as well as the adipocytokine IL-1 ra (25%). EX independently improved IR, while both EX and LFD improved HS. These findings suggest that both diet and exercise have unique beneficial effects on WAT inflammatory markers and the mechanism by which each treatment improves metabolic complications associated with chronic consumption of an HFD may be different.
Project description:While the main function of white adipose tissue (WAT) is to store surplus of energy as triacylglycerol, that of brown adipose tissue (BAT) is to burn energy as heat. Epigenetic mechanisms participate prominently in both WAT and BAT energy metabolism. We previously reported that the histone demethylase ubiquitously transcribed tetratricopeptide (Utx) is a positive regulator of brown adipocyte thermogenesis. Here, we aimed to investigate whether Utx also regulates WAT metabolism in vivo. We generated a mouse model with Utx deficiency in adipocytes (AUTXKO). AUTXKO animals fed a chow diet had higher body weight, more fat mass and impaired glucose tolerance. AUTXKO mice also exhibited cold intolerance with an impaired brown fat thermogenic program. When challenged with high-fat diet (HFD), AUTXKO mice displayed adipose dysfunction featured by suppressed lipogenic pathways, exacerbated inflammation and fibrosis with less fat storage in adipose tissues and more lipid storage in the liver; as a result, AUTXKO mice showed a disturbance in whole body glucose homeostasis and hepatic steatosis. Our data demonstrate that Utx deficiency in adipocytes limits adipose tissue expansion under HFD challenge and induces metabolic dysfunction via adipose tissue remodeling. We conclude that adipocyte Utx is a key regulator of systemic metabolic homeostasis.
Project description:In order to establish an obese mouse model, female mice were continuously fed with a high-fat diet (HFD) or a normal diet (control) for 16 weeks beginning at three weeks of age. In this paper, these mice are termed ‘HFD mice’ and ‘control mice’, respectively. Accordingly, we call their oocytes ‘HFD oocytes’ and ‘control oocytes’. Substantial evidence indicates that the effects of maternal obesity on embryo/offspring development can be attributed to factors within the oocyte (9). To identify such potential effectors, we performed a comparative proteomic analysis of ovulated MII oocytes from control and HFD mice.
Project description:Introduction: Nonalcoholic fatty liver disease (NAFLD) is associated with metabolic syndrome, which often includes obesity, diabetes, and dyslipidemia. Several studies in mice and humans have implicated the involvement of the gut microbiome in NAFLD. While cannabis may potentially be beneficial for treating metabolic disorders such as NAFLD, the effects of cannabis on liver diseases and gut microbiota profile are yet to be addressed. In this study, we evaluated the therapeutic effects of cannabis strains with different cannabinoid profiles on NAFLD progression. Materials and Methods: NAFLD was induced by feeding mice a high-fat/cholesterol diet (HFCD) for 6 weeks. During this period, cannabis extracts were administrated orally at a concentration of 5 mg/kg every 3 days. Profile of lipids, liver enzymes, glucose tolerance, and gene expression related to carbohydrate lipid metabolism and liver inflammation were analyzed. The effect of cannabis strains on microbiota composition in the gut was evaluated. Results: A cannabidiol (CBD)-rich extract produced an increase in inflammatory related gene expression and a less diverse microbiota profile, associated with increased fasting glucose levels in HFCD-fed mice. In contrast, mice receiving a tetrahydrocannabinol (THC)-rich extract exhibited moderate weight gain, improved glucose response curves, and a decrease in liver enzymes. Conclusions: The results of this study indicate that the administration of cannabis containing elevated levels of THC may help ameliorate symptoms of NAFLD, whereas administration of CBD-rich cannabis extracts may cause a proinflammatory effect in the liver, linked with an unfavorable change in the microbiota profile. Our preliminary data suggest that these effects are mediated by mechanisms other than increased expression of the endocannabinoid receptors cannabinoid receptor 1 (CB1) and CB2.
Project description:Cholesterol 7?-hydroxylase (CYP7A1) is the first and rate-limiting enzyme in the conversion of cholesterol to bile acids in the liver. In addition to absorption and digestion of nutrients, bile acids play a critical role in the regulation of lipid, glucose, and energy homeostasis. We have backcrossed Cyp7a1(-/-) mice in a mixed B6/129Sv genetic background to C57BL/6J mice to generate Cyp7a1(-/-) mice in a near-pure C57BL/6J background. These mice survive well and have normal growth and a bile acid pool size ?60% of WT mice. The expression of the genes in the alternative bile acid synthesis pathway are upregulated, resulting in a more hydrophilic bile acid composition with reduced cholic acid (CA). Surprisingly, Cyp7a1(-/-) mice have improved glucose sensitivity with reduced liver triglycerides and fecal bile acid excretion, but increased fecal fatty acid excretion and respiratory exchange ratio (RER) when fed a high-fat/high-cholesterol diet. Supplementing chow and Western diets with CA restored bile acid composition, reversed the glucose tolerant phenotype, and reduced the RER. Our current study points to a critical role of bile acid composition, rather than bile acid pool size, in regulation of glucose, lipid, and energy metabolism to improve glucose and insulin tolerance, maintain metabolic homeostasis, and prevent high-fat diet-induced metabolic disorders.
Project description:Aims/hypothesisDespite the current pandemic of metabolic diseases, our understanding of the diverse nature of the development of metabolic alterations in people who eat a high-fat diet (HFD) is still poor. We recently demonstrated a cardio-metabolic adaptation in mice fed an HFD, which was characterised by a specific gut and periodontal microbiota profile. Since the severity of hepatic disease is characterised by specific microRNA (miRNA) signatures and the gut microbiota is a key driver of both hepatic disease and miRNA expression, we analysed the expression of three hepatic miRNA and studied their correlation with hepatic triacylglycerol content and gut microbiota.MethodsTwo cohorts of C57BL/6 4-week-old wild-type (WT) male mice (n = 62 and n = 96) were fed an HFD for 3 months to provide a model of metabolic adaptation. Additionally 8-week-old C57BL/6 mice, either WT or of different genotypes, with diverse gut microbiota (ob/ob, Nod1, Cd14 knockout [Cd14KO] and Nod2) or without gut microbiota (axenic mice) were fed a normal chow diet. Following which, glycaemic index, body weight, blood glucose levels and hepatic triacylglycerol levels were measured. Gut (caecum) microbiota taxa were analysed by pyrosequencing. To analyse hepatic miRNA expression, real-time PCR was performed on total extracted miRNA samples. Data were analysed using two-way ANOVA followed by the Dunnett's post hoc test, or by the unpaired Student's t test. A cluster analysis and multivariate analyses were also performed.ResultsOur results demonstrated that the expression of miR-181a, miR-666 and miR-21 in primary murine hepatocytes is controlled by lipopolysaccharide in a dose-dependent manner. Of the gut microbiota, Firmicutes were positively correlated and Proteobacteria and Bacteroides acidifaciens were negatively correlated with liver triacylglycerol levels. Furthermore, the relative abundance of Firmicutes was negatively correlated with hepatic expression of miR-666 and miR-21. In contrast, the relative abundance of B. acidifaciens was positively correlated with miR-21.Conclusions/interpretationWe propose the involvement of hepatic miRNA, liver triacylglycerols and gut microbiota as a new triad that underlies the molecular mechanisms by which gut microbiota governs hepatic pathophysiology during metabolic adaptation to HFD.
Project description:Aims/hypothesisDespite a similar fat storing function, visceral (intra-abdominal) white adipose tissue (WAT) is detrimental, whereas subcutaneous WAT is considered to protect against metabolic disease. Recent findings indicate that thermogenic genes, expressed in brown adipose tissue (BAT), can be induced primarily in subcutaneous WAT. Here, we investigate the hypothesis that the Wilms tumour gene product (WT1), which is expressed in intra-abdominal WAT but not in subcutaneous WAT and BAT, suppresses a thermogenic program in white fat cells.MethodsHeterozygous Wt1 knockout mice and their wild-type littermates were examined in terms of thermogenic and adipocyte-selective gene expression. Glucose tolerance and hepatic lipid accumulation in these mice were assessed under normal chow and high-fat diet conditions. Pre-adipocytes isolated from the stromal vascular fraction of BAT were transduced with Wt1-expressing retrovirus, induced to differentiate and analysed for the expression of thermogenic and adipocyte-selective genes.ResultsExpression of the thermogenic genes Cpt1b and Tmem26 was enhanced and transcript levels of Ucp1 were on average more than tenfold higher in epididymal WAT of heterozygous Wt1 knockout mice compared with wild-type mice. Wt1 heterozygosity reduced epididymal WAT mass, improved whole-body glucose tolerance and alleviated severe hepatic steatosis upon diet-induced obesity in mice. Retroviral expression of WT1 in brown pre-adipocytes, which lack endogenous WT1, reduced mRNA levels of Ucp1, Ppargc1a, Cidea, Prdm16 and Cpt1b upon in vitro differentiation by 60-90%. WT1 knockdown in epididymal pre-adipocytes significantly lowered Aldh1a1 and Zfp423 transcripts, two key suppressors of the thermogenic program. Conversely, Aldh1a1 and Zfp423 mRNA levels were increased approximately five- and threefold, respectively, by retroviral expression of WT1 in brown pre-adipocytes.Conclusion/interpretationWT1 functions as a white adipocyte determination factor in epididymal WAT by suppressing thermogenic genes. Reducing Wt1 expression in this and other intra-abdominal fat depots may represent a novel treatment strategy in metabolic disease.