Project description:Germfree (GF) mice have been used as a model to study the contribution of the intestinal microbiota to metabolic energy balance of the host. Despite a wealth of knowledge accumulated since the 1940’s, the response of GF mice to a high fat diet is largely unknown. In the present study, we compared the metabolic consequences of a high fat (HF) diet on GF and conventional (Conv) C57BL/6J mice. As expected, Conv mice developed obesity and glucose intolerance with a HF diet. In contrast, GF mice remained lean and resisted the HF diet-induced insulin resistance. The anti-obesity phenotype of GF/HF mice was accompanied by reduced caloric intake, diminished food efficiency, and excessive fecal lipid excretion contributed to the reduced food efficiency. In addition, HF diet-induced hypercholesterolemia was ameliorated, which was partially due to an increase in fecal cholesterol excretion. However, hepatic cholesterols were increased in GF/HF mice. Elevated nuclear SREBP2 proteins and the up-regulation of cholesterol biosynthesis genes support the increased liver cholesterol biosynthesis in GF/HF mice. The resistance to HF diet-induced metabolic abnormalities in GF mice was also associated with a reduced immune response, indicated by low plasma pro-inflammatory and anti-inflammatory markers. These data suggest that the gut microbiota of Conv mice contributes to HF diet-induced obesity, insulin resistance, dyslipidemia and hepatic steatosis in mice. Thus, results of the present study describe the metabolic responses of GF mice to a HF diet and further our understandings of the relationship between the gut microbiota and the host. Germfree and conventional C57BL/6J mice were fed with a high fat diet for 11 weeks. Then, all mice were sacrified under 10-h food deprevation, and liver samples of germfree (n=14) and conventional (n=16) were examined.
Project description:Germfree (GF) mice have been used as a model to study the contribution of the intestinal microbiota to metabolic energy balance of the host. Despite a wealth of knowledge accumulated since the 1940’s, the response of GF mice to a high fat diet is largely unknown. In the present study, we compared the metabolic consequences of a high fat (HF) diet on GF and conventional (Conv) C57BL/6J mice. As expected, Conv mice developed obesity and glucose intolerance with a HF diet. In contrast, GF mice remained lean and resisted the HF diet-induced insulin resistance. The anti-obesity phenotype of GF/HF mice was accompanied by reduced caloric intake, diminished food efficiency, and excessive fecal lipid excretion contributed to the reduced food efficiency. In addition, HF diet-induced hypercholesterolemia was ameliorated, which was partially due to an increase in fecal cholesterol excretion. However, hepatic cholesterols were increased in GF/HF mice. Elevated nuclear SREBP2 proteins and the up-regulation of cholesterol biosynthesis genes support the increased liver cholesterol biosynthesis in GF/HF mice. The resistance to HF diet-induced metabolic abnormalities in GF mice was also associated with a reduced immune response, indicated by low plasma pro-inflammatory and anti-inflammatory markers. These data suggest that the gut microbiota of Conv mice contributes to HF diet-induced obesity, insulin resistance, dyslipidemia and hepatic steatosis in mice. Thus, results of the present study describe the metabolic responses of GF mice to a HF diet and further our understandings of the relationship between the gut microbiota and the host.
Project description:Background: Exposure to persistent organic pollutants (POPs) and disruptions in the gastrointestinal microbiota have been positively correlated with a predisposition to factors such as obesity, metabolic syndrome, and type 2 diabetes; however, it is unclear how the microbiome contributes to this relationship.
Objective: This study aimed to explore the association between early-life exposure to a potent aryl hydrocarbon receptor (AHR) agonist and persistent disruptions in the microbiota, leading to impaired metabolic homeostasis later in life.
Methods: This study utilized metagenomics, NMR- and mass spectrometry-based metabolomics, and biochemical assays to analyze the gut microbiome composition and function, as well as the physiological and metabolic effects of early-life exposure to 2,3,7,8-tetrachlorodibenzofuran (TCDF) in conventional, germ-free (GF), and Ahr-null mice. The impact of TCDF on Akkermansia muciniphila (A. muciniphila) in vitro was assessed using optical density (OD 600), flow cytometry, transcriptomics, and mass spectrometry-based metabolomics.
Results: TCDF-exposed mice exhibited disruption in the gut microbiome community structure and function, characterized by lower abundances of A. muciniphila, lower levels of cecal short chain fatty acids (SCFAs) and indole-3-lactic acid (ILA), and a reduction in gut hormones GLP-1 and PYY. Importantly, microbial and metabolic phenotypes associated with early-life POP exposure were transferable to GF recipients in the absence of POP carry-over. In addition, AHR-independent interactions between POPs and the microbiota were observed, significantly affected the growth, physiology, gene expression, and metabolic activity of A. muciniphila, resulting in suppressed activity along the ILA pathway.
Conclusions: These data point to the complex effects of POPs on the host and microbiota, providing strong evidence that early-life, short-term, and self-limiting POP exposure can adversely impact the microbiome, persisting into later life with associated health implications.
Project description:Obesity and overweight are closely related to diet, and gut microbiota play an important role in body weight and human health. The aim of this study was to explore how Lactobacillus curvatus HY7601 and Lactobacillus plantarum KY1032 supplementation alleviate obesity by modulating the human gut microbiome. A randomized, double-blind, placebo-controlled study was conducted on 72 overweight individuals. Over a 12-week period, probiotic groups consumed 5×10^9 colony-forming units of HY7601 and KY1032), whereas the placebo group consumed the same product without probiotics. After treatment, the probiotic group displayed a reduction in body weight (p <0.001), visceral fat mass (p <0.025), and waist circumference (p <0.007), and an increase in adiponectin (p <0.046), compared with the placebo group. Additionally, HY7601 and KY1032 supplementation modulated bacterial gut microbiota characteristics and beta diversity by increasing Bifidobacteriaceae and Akkermansiaceae, and decreasing Prevotellaceae and Selenomonadaceae. In summary, HY7601 and KY1032 probiotics exert anti-obesity effects by regulating the gut microbiota; hence, they have therapeutic potential for preventing or alleviating obesity and overweight.
Project description:Auricularia auricula is a well-known traditional edible and medicinal fungus with high nutritional and pharmacological values, as well as metabolic and immunoregulatory properties. However, the exact mechanisms underlying the effects of Auricularia auricula polysaccharides (AAP) on obesity and related metabolic endpoints, including the role of the gut microbiota, remain insufficiently understood. To determine the mechanistic role of the gut microbiota in observed anti-obesogenic effects AAP, faecal microbiota transplantation (FMT) and pseudo germ-free mice model treated with antibiotics were also applied, together with 16S rRNA genomic-derived taxonomic profiling. HFD murine exposure to AAP thwarted weight-gains, reduced fat depositing, together with upregulating thermogenesis proteomic biomarkers within adipose tissue. These effects were associated with diminished intestine/bloodstream-borne lipid transportation, together with enhanced glucose tolerance. FMT administered in tandem with antibiotic treatment demonstrated the intestinal microbiota was necessary in deploying AAP anti-obesogenic functions. Intestine-dwelling microbial population assessments discovered AAP to enhance (in a selective manner) Papillibacter cinnamivorans, a commensal bacterium having reduced presence within HFD mice. Notably, HFD mice treated with oral formulations of Papillibacter cinnamivorans diminished obesity and was linked to decreased intestinal lipid transportation. Datasets from the present study show that AAP thwarted dietary-driven obesity and metabolism-based disorders through regulating intestinal lipid transportation, a mechanism that is dependent on the gut commensal Papillibacter cinnamivorans. These results indicated AAP and Papillibacter cinnamivorans as newly identified pre- and probiotics that could possibly serve as novel countermeasure against obesity.