Project description:Morphine and its pharmacological derivatives are the most prescribed analgesics for moderate to severe pain management. However, chronic use of morphine reduces pathogen clearance and induces bacterial translocation across the gut barrier. The enteric microbiome has been shown to play a critical role in the preservation of the mucosal barrier function and metabolic homeostasis. Here, we show for the first time, using bacterial 16s rDNA sequencing, that chronic morphine treatment significantly alters the gut microbial composition and induces preferential expansion of the gram-positive pathogenic and reduction of bile-deconjugating bacterial strains. A significant reduction in both primary and secondary bile acid levels was seen in the gut, but not in the liver with morphine treatment. Morphine induced microbial dysbiosis and gut barrier disruption was rescued by transplanting placebo-treated microbiota into morphine-treated animals, indicating that microbiome modulation could be exploited as a therapeutic strategy for patients using morphine for pain management. In this study, we establish a link between the two phenomena, namely gut barrier compromise and dysregulated bile acid metabolism. We show for the first time that morphine fosters significant gut microbial dysbiosis and disrupts cholesterol/bile acid metabolism. Changes in the gut microbial composition is strongly correlated to disruption in host inflammatory homeostasis13,14 and in many diseases (e.g. cancer/HIV infection), persistent inflammation is known to aid and promote the progression of the primary morbidity. We show here that chronic morphine, gut microbial dysbiosis, disruption of cholesterol/bile acid metabolism and gut inflammation; have a linear correlation. This opens up the prospect of devising minimally invasive adjunct treatment strategies involving microbiome and bile acid modulation and thus bringing down morphine-mediated inflammation in the host.
Project description:Antibiotic induced microbiome depletion (AIMD) has been used frequently to study the role of the gut microbiome in pathological conditions. However, unlike germ-free mice, the effects of AIMD on host metabolism is unknown. We investigated the effects of AIMD in normal-chow fed mice to understand its effects on gut homeostasis, luminal signaling, and metabolism. We show that AIMD, which decreases luminal Firmicutes and Bacteroidetes species, decreases baseline serum glucose levels, reduces glucose surge in a tolerance test, and improves insulin sensitivity without altering adiposity. These occur in the setting of decreased luminal short-chain fatty acids (SCFAs), especially butyrate, and secondary bile acid (BA) pool, which affects whole-body BA metabolism. In mice, AIMD alters cecal gene expression and gut GLP-1 signaling. Extensive tissue remodeling and decreased availability of SCFAs shift colonocyte metabolism toward glucose utilization. Hence, AIMD alters whole-body glucose homeostasis by potentially shifting colonocyte energy utilization from SCFAs to glucose.
Project description:Purpose: While various functions of peripheral serotonin are known, the direct role of serotonin in regulating hepatic lipid metabolism in vivo is not well understood. We studied whether serotonin directly acts on liver to regulate lipid metabolism. Methods: Methods: 12 weeks aged liver-specific Htr2a KO (Albumin-Cre+/-; Htr2aflox/flox, herein named Htr2a LKO) mice and wildtype (WT) littermates were fed a high-fat diet (HFD, 60% fat calories) for 8 weeks. Results: Hepatic lipid droplet accumulation, NAFLD activity score, and hepatic triglyceride levels were dramatically reduced in HFD-fed Htr2a LKO mice compared to WT littermates. Conclusions: Gut-derived serotonin is a direct regulator of hepatic lipid metabolism via a gut TPH1-liver HTR2A endocrine axis. And shows promise as a novel drug target to ameliorate NAFLD with minimal systemic metabolic effects.
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:Gut microbiota and the circadian clock are both key regulators of the metabolic processes. Although recent evidence points to the impact of the circadian clock on microbiota, gut microbiota effect on diurnal host gene expression remains elusive. A transcriptome analysis of germ-free mice reveals subtle changes in circadian clock gene expression. However, a lack of microbiome leads to liver feminization and alters the expression of male-specific genes involved in lipid metabolism and xenobiotic detoxification associated with sustained activation of the Growth Hormone pathway. These results emphasize the mutual interaction of gut microbiota and its host even on unexpected functions.
Project description:Gut microbiota and the circadian clock are both key regulators of the metabolic processes. Although recent evidence points to the impact of the circadian clock on microbiota, gut microbiota effect on diurnal host gene expression remains elusive. A transcriptome analysis of germ-free mice reveals subtle changes in circadian clock gene expression. However, a lack of microbiome leads to liver feminization and alters the expression of male-specific genes involved in lipid metabolism and xenobiotic detoxification associated with sustained activation of the Growth Hormone pathway. These results emphasize the mutual interaction of gut microbiota and its host even on unexpected functions.
Project description:Gut microbiota and the circadian clock are both key regulators of the metabolic processes. Although recent evidence points to the impact of the circadian clock on microbiota, gut microbiota effect on diurnal host gene expression remains elusive. A transcriptome analysis of germ-free mice reveals subtle changes in circadian clock gene expression. However, a lack of microbiome leads to liver feminization and alters the expression of male-specific genes involved in lipid metabolism and xenobiotic detoxification associated with sustained activation of the Growth Hormone pathway. These results emphasize the mutual interaction of gut microbiota and its host even on unexpected functions.
Project description:Gut microbiota and the circadian clock are both key regulators of the metabolic processes. Although recent evidence points to the impact of the circadian clock on microbiota, gut microbiota effect on diurnal host gene expression remains elusive. A transcriptome analysis of germ-free mice reveals subtle changes in circadian clock gene expression. However, a lack of microbiome leads to liver feminization and alters the expression of male-specific genes involved in lipid metabolism and xenobiotic detoxification associated with sustained activation of the Growth Hormone pathway. These results emphasize the mutual interaction of gut microbiota and its host even on unexpected functions.
Project description:Metformin is the therapy of choice for treating type 2 diabetes and is currently repurposed for a wide range of diseases including aging. Recent evidence implicates the gut microbiota as a site of metformin action. Combining two tractable genetic models, the bacterium E. coli and the nematode C. elegans, we performed C. elegans RNAseq to investigate the role of the metformin sensitive OP50 and metformin resistant OP50-MR E. coli microbiota in the drug effects on the host. Our data suggest an evolutionarily conserved bacterial mediation of metformin effects on host lipid metabolism and lifespan.