Project description:Animals must learn through experience which foods are nutritious and should be consumed, and which are toxic and should be avoided. Enteroendocrine cells (EECs) are the principal chemosensors in the GI tract, but investigation of their role in behavior has been limited by the difficulty of selectively targeting these cells in vivo. Here we describe an intersectional genetic approach for manipulating EEC subtypes in behaving mice. We show that multiple EEC subtypes inhibit food intake but have different effects on learning. Conditioned flavor preference is driven by release of cholecystokinin whereas conditioned taste aversion is mediated by serotonin and substance P. These positive and negative valence signals are transmitted by vagal and spinal afferents, respectively. These findings establish a cellular basis for how chemosensing in the gut drives learning about food.
Project description:Background: More than 100 million Americans are living with metabolic syndrome, increasing their propensity to develop heart disease– the leading cause of death worldwide. A major contributing factor to this epidemic is caloric excess, often a result of consuming low cost, high calorie fast food. Several recent seminal studies have demonstrated the pivotal role of gut microbes contributing to cardiovascular disease in a diet-dependent manner. Given the central contributions of diet and gut microbiota to cardiometabolic disease, we hypothesized that novel microbial metabolites originating postprandially after fast food consumption may contribute to cardiometabolic disease progression. Methods: To test this hypothesis, we gave conventionally raised or antibiotic-treated mice a single oral gavage of a fast food slurry or a control rodent chow diet slurry and sacrificed the mice four hours later. Here, we coupled untargeted metabolomics in portal and peripheral blood, 16S rRNA gene sequencing, targeted liver metabolomics, and host liver RNA sequencing to identify novel fast food-derived microbial metabolites. Results: We successfully identified several metabolites that were enriched in portal blood, increased by fast food feeding, and essentially absent in antibiotic-treated mice. Strikingly, just four hours post-gavage, we found that fast food consumption resulted in rapid reorganization of the gut microbial community structure and drastically altered hepatic gene expression. Importantly, diet-driven reshaping of the microbiome and liver transcriptome was dependent on a non-antibiotic ablated gut microbial community. Conclusions: Collectively, these data suggest that single fast food meal is sufficient to reshape the gut microbial community yielding a unique signature of food-derived microbial metabolites. Future studies are warranted to determine if these metabolites are causally linked to cardiometabolic disease.
Project description:Obesity is a risk factor for Osteoarthritis (OA), the greatest cause of disability in the US. The impact of obesity on OA is driven by systemic inflammation, now understood to be caused by an altered gut microbiome. Oligofructose, a non-digestible prebiotic fiber, can correct the obese gut microbiome, suggesting a novel approach to treat the OA of obesity. Here we report that in the obese murine gut, beneficial Bifidobacteria are lost while key proinflammatory species gain in abundance. A downstream systemic inflammatory signature culminates with accelerated knee OA. Oligofructose supplementation corrects the obese gut microbiome in part by supporting key commensal microflora, particularly Bifidobacterium pseudolongum. This leads to reduced inflammation in the colon, circulation and knee, and protection from OA. This novel recognition of a gut microbiome-OA connection sets the stage for discovery of new OA therapeutics targeting specific microbes inhabiting the intestinal space to inhibit disease pathology.
Project description:Intestinal surface changes in size and function in response to environmental conditions, but what propels these alterations and what are the metabolic consequences is not clear. Here we show that in mice gut surface enlarges by increasing food amount rather than caloric intake, contributing to an increased absorptive function, and that it can be reversed by reducing daily food amount. Genetic- and environment-induced gut enlargement due to overeating is principally supported by upregulation of the intestinal lipid metabolism and transport. Intestinal knock-out, and pharmacological inhibition of PPARα supress intestinal crypt formation and shorten villi in the small intestine of mice and in human intestinal biopsies, respectively, and diminish post-prandial triglyceride transport and nutrient uptake. PPARα inhibition limits lipid absorption and restricts lipid droplet growth and PLIN2 levels, critical for the droplet formation. This improves lipid metabolism, reduces body adiposity and liver steatosis, suggesting an alternative target for treating obesity.
Project description:The increasing prevalence of obesity and related metabolic disorders represents a growing public health concern. Despite advances in other areas of medicine, a safe and effective drug treatment for obesity has been elusive. Obesity has repeatedly been linked to reorganization of the gut microbiome 1-4 , yet to this point obesity therapeutics have been targeted exclusively toward the human host. Here we show that gut microbe-targeted inhibition of the metaorganismal trimethylamine N-oxide (TMAO) pathway protects mice against the metabolic disturbances associated with diet-induced obesity (DIO) or leptin deficiency (ob/ob). Selective small molecule inhibition of the gut microbial enzyme choline TMA-lyase (CutC) does not significantly reduce food intake, but instead is associated with beneficial remodeling of the gut microbiome, improvement in glucose tolerance, and enhanced energy expenditure. Leveraging untargeted metabolomics we discovered that CutC inhibition is associated with reorganization of host circadian control of both phosphatidylcholine and energy metabolism. Collectively, this study underscores the close relationship between microbe and host metabolism, and provides evidence that gut microbe-derived trimethylamine (TMA) is a key regulator of the host circadian clock. This work also demonstrates that gut microbe-targeted enzyme inhibitors can have profound effects on host energy metabolism, and have untapped potential as anti-obesity therapeutics.
Project description:Mining waste streams of food production for bioactive plant polysaccharides that affect the fitness and expressed activities of targeted human gut microbes
Project description:Diet-induced obesity (DIO) is rapidly becoming a global health problem, particularly as Westernization of emerging nations continues. Currently, one third of adult Americans are considered obese and, if current trends continue, >90% of US citizens are predicted to be affected by 2050. However, efforts to fight this epidemic have not yet produced sound solutions for prevention or treatment. Our studies reveal a balanced and chronobiological relationship between food consumption, daily variation in gut microbial evenness and function, basomedial hypothalamic circadian clock (CC) gene expression, and key hepatic metabolic regulatory networks , including CC and nuclear receptors (NR), that is are essential for metabolic homeostasis. “Western” diets high in saturated fats dramatically alter diurnal variation in microbial composition and function, which in turn lead to uncoupling of the hepatic CC and NR networks from central CC control in ways that offset the timing and types of regulatory factors directing metabolic function. These signals include microbial metabolites such as short chain fatty acids (SCFAs) and hydrogen sulfide (H2S) that can directly regulate or disrupt metabolic networks of the hepatocyte. Our study therefore provides insights into the complex and dynamic relationships between diet, gut microbes, and the host that are critical for maintenance of health. Perturbations of this constellation of processes, in this case by diet-induced dysbiosis and its metabolomic signaling, can potentially promote metabolic imbalances and disease. This knowledge opens up many possibilities for novel therapeutic and interventional strategies to treat and prevent DIO, ranging from the manipulation of gut microbial function to pharmacological targeting of host pathways to restore metabolic balance. Mice were raised under germ-free or specific pathogen-free condition, or germ-free followed by conventionization. Liver tissues were harvested for total RNA isolation and hybridization on Affymetrix microarrays
Project description:<p>Emerging evidence that the gut microbiota may contribute in important ways to human health and disease has led us and others to hypothesize that both symbiotic and pathological relationships between gut microbes and their host may be key contributors to obesity and the metabolic complications of obesity. Our "Thrifty Microbiome Hypothesis" poses that gut microbiota play a key role in human energy homeostasis. Specifically, constituents of the gut microbial community may introduce a survival advantage to its host in times of nutrient scarcity, promoting positive energy balance by increasing efficiency of nutrient absorption and improving metabolic efficiency and energy storage. However, in the presence of excess nutrients, fat accretion and obesity may result, and in genetically predisposed individuals, increased fat mass may result in preferential abdominal obesity, ectopic fat deposition (liver, muscle), and metabolic complications of obesity (insulin resistance, hypertension, hyperlipidemia). Furthermore, in the presence of excess nutrients, a pathological transition of the gut microbial community may occur, causing leakage of bacterial products into the intestinal lymphatics and portal circulation, thereby inducing an inflammatory state, further aggravating metabolic syndrome traits and accelerating atherosclerosis. This pathological transition and the extent to which antimicrobial leakage occurs and causes inflammatory and other maladaptive sequelae of obesity may also be influenced by host factors, including genetics. In the proposed study, we will directly test the Thrifty Microbiome Hypothesis by performing detailed genomic and functional assessment of gut microbial communities in intensively phenotyped and genotyped human subjects before and after intentional manipulation of the gut microbiome. To address these hypotheses, five specific aims are proposed: (1) enroll three age- and sex-matched groups from the Old Order Amish: (i) 50 obese subjects (BMI > 30 kg/m2) with metabolic syndrome, (ii) 50 obese subjects (BMI > 30 kg/m2) without metabolic syndrome, and (iii) 50 non-obese subjects (BMI < 25 kg/m2) without metabolic syndrome and characterize the architecture of the gut microbiota from the subjects enrolled in this study by high-throughput sequencing of 16S rRNA genes; (2) characterize the gene content (metagenome) to assess the metabolic potential of the gut microbiota in 75 subjects to determine whether particular genes or pathways are correlated with disease phenotype; (3) characterize the transcriptome in 75 subjects to determine whether differences in gene expression in the gut microbiota are correlated with disease phenotype, (4) determine the effect of manipulation of the gut microbiota with antibiotics on energy homeostasis, inflammation markers, and metabolic syndrome traits in 50 obese subjects with metabolic syndrome and (5) study the relationship between gut microbiota and metabolic and cardiovascular disease traits, weight change, and host genomics in 1,000 Amish already characterized for these traits and in whom 500K Affymetrix SNP chips have already been completed. These studies will provide our deepest understanding to date of the role of gut microbes in terms of 'who's there?', 'what are they doing?', and 'how are they influencing host energy homeostasis, obesity and its metabolic complications? PUBLIC HEALTH RELEVANCE: This study aims to unravel the contribution of the bacteria that normally inhabit the human gastrointestinal tract to the development of obesity, and its more severe metabolic consequences including cardiovascular disease, insulin resistance and Type II diabetes. We will take a multidisciplinary approach to study changes in the structure and function of gut microbial communities in three sets of Old Order Amish patients from Lancaster, Pennsylvania: obese patients, obese patients with metabolic syndrome and non-obese individuals. The Old Order Amish are a genetically closed homogeneous Caucasian population of Central European ancestry ideal for genetic studies. These works have the potential to provide new mechanistic insights into the role of gut microflora in obesity and metabolic syndrome, a disease that is responsible for significant morbidity in the adult population, and may ultimately lead to novel approaches for prevention and treatment of this disorder.</p>
Project description:This is a pilot feasibility study designed to investigate the alterations in the gut microbiome that occur during the course of treatment for colorectal cancer