Project description:The importance of the mammalian intestinal microbiota to human health has been intensely studied over the past few years. It is now clear that the interactions between human hosts and their associated microbial communities need to be characterized in molecular detail if we are to truly understand human physiology. Additionally, the study of such host-microbe interactions is likely to provide us with new strategies to manipulate such complex systems to maintain or restore homeostasis in order to prevent or cure pathological states. We describe the use of high-throughput metabolomics to shed light on the interactions between the intestinal microbiota and the host. We show that treatment with the antibiotic streptomycin disrupts intestinal homeostasis and has a profound impact on the intestinal metabolome, affecting the levels of over 87% of all metabolites detected. Many metabolic pathways that are critical for host physiology were affected, including bile acid, eicosanoid and steroid hormone synthesis. Interestingly, many of these pathways are also affected by intestinal pathogens. Dissecting the effect of both beneficial and pathogenic bacteria on some of these pathways will be instrumental in understanding the interplay between the host, the resident microbiota and incoming pathogens and may aid in the design of new therapeutic strategies that target these interactions.
Project description:The intestinal microbiota has been identified as an environmental factor that markedly impacts energy storage and body fat accumulation, yet the underlying mechanisms remain unclear. Here we show that the microbiota regulates body composition through the circadian transcription factor NFIL3. Nfil3 transcription oscillates diurnally in intestinal epithelial cells and the amplitude of the circadian oscillation is controlled by the microbiota through type 3 innate lymphoid cells (ILC3), STAT3, and the epithelial cell circadian clock. NFIL3 controls expression of a circadian lipid metabolic program and regulates lipid absorption and export in intestinal epithelial cells. These findings provide mechanistic insight into how the intestinal microbiota regulates body composition and establish NFIL3 as an essential molecular link among the microbiota, the circadian clock, and host metabolism.
Project description:Neural control of visceral organ function is essential for homeostasis and health. Intestinal peristalsis is critical for digestive physiology and host defence and is often dysregulated in gastrointestinal (GI) disorders. Luminal factors, such as diet and microbiota regulate neurogenic programs of gut motility, but the underlying molecular mechanisms remain unclear. Here we show that the transcription factor Aryl hydrocarbon Receptor (AhR) functions as a biosensor in intestinal neural circuits linking their functional output to the microbial environment of the gut lumen. Using nuclear RNA sequencing of mouse enteric neurons representing distinct intestinal segments and microbiota states, we demonstrate that the intrinsic neural networks of the colon exhibit unique transcriptional profiles controlled by the combined effects of host genetic programmes and microbial colonisation. Microbiota-induced expression of AhR in neurons of the distal gastrointestinal tract enables them to respond to the luminal environment and induce expression of neuron-specific effector mechanisms. Neuron-specific deletion of Ahr or constitutive overexpression of its negative feedback regulator CYP1A1, results in reduced peristaltic activity of the colon, similar to that observed in microbiota-depleted mice. Finally, expression of Ahr in enteric neurons of antibiotic-treated mice partially restores intestinal motility. Taken together, our experiments identify AhR signalling in enteric neurons as a regulatory node that integrates the luminal environment with the physiological output of intestinal neural circuits towards gut homeostasis and health. The enteric nervous system (ENS) encompasses the intrinsic neural networks of the gastrointestinal (GI) tract, which regulate most aspects of intestinal physiology, including peristalsis. In addition to host-specific genetic programmes, microbiota and diet have emerged as critical regulators of gut tissue physiology and changes in the microbial composition of the lumen often accompany GI disorders. However the molecular mechanisms by which gut enviromental factors regulate ENS homeostasis remain unknown. In order to address this issue, we used RNA sequencing to identify genes specifically upregulated in mouse colonic neurons in response to microbial colonisation.
Project description:Neural control of visceral organ function is essential for homeostasis and health. Intestinal peristalsis is critical for digestive physiology and host defence and is often dysregulated in gastrointestinal (GI) disorders. Luminal factors, such as diet and microbiota regulate neurogenic programs of gut motility, but the underlying molecular mechanisms remain unclear. Here we show that the transcription factor Aryl hydrocarbon Receptor (AhR) functions as a biosensor in intestinal neural circuits linking their functional output to the microbial environment of the gut lumen. Using nuclear RNA sequencing of mouse enteric neurons representing distinct intestinal segments and microbiota states, we demonstrate that the intrinsic neural networks of the colon exhibit unique transcriptional profiles controlled by the combined effects of host genetic programmes and microbial colonisation. Microbiota-induced expression of AhR in neurons of the distal gastrointestinal tract enables them to respond to the luminal environment and induce expression of neuron-specific effector mechanisms. Neuron-specific deletion of Ahr or constitutive overexpression of its negative feedback regulator CYP1A1, results in reduced peristaltic activity of the colon, similar to that observed in microbiota-depleted mice. Finally, expression of Ahr in enteric neurons of antibiotic-treated mice partially restores intestinal motility. Taken together, our experiments identify AhR signalling in enteric neurons as a regulatory node that integrates the luminal environment with the physiological output of intestinal neural circuits towards gut homeostasis and health. The enteric nervous system (ENS) encompasses the intrinsic neural networks of the gastrointestinal (GI) tract, which regulate most aspects of intestinal physiology, including peristalsis. In addition to host-specific genetic programmes, microbiota and diet have emerged as critical regulators of gut tissue physiology and changes in the microbial composition of the lumen often accompany GI disorders. However the molecular mechanisms by which gut enviromental factors regulate ENS homeostasis remain unknown. In order to address this issue, we used RNA sequencing to identify genes specifically upregulated in mouse colonic neurons in response to microbial colonisation.
Project description:Neural control of visceral organ function is essential for homeostasis and health. Intestinal peristalsis is critical for digestive physiology and host defence and is often dysregulated in gastrointestinal (GI) disorders. Luminal factors, such as diet and microbiota regulate neurogenic programs of gut motility, but the underlying molecular mechanisms remain unclear. Here we show that the transcription factor Aryl hydrocarbon Receptor (AhR) functions as a biosensor in intestinal neural circuits linking their functional output to the microbial environment of the gut lumen. Using nuclear RNA sequencing of mouse enteric neurons representing distinct intestinal segments and microbiota states, we demonstrate that the intrinsic neural networks of the colon exhibit unique transcriptional profiles controlled by the combined effects of host genetic programmes and microbial colonisation. Microbiota-induced expression of AhR in neurons of the distal gastrointestinal tract enables them to respond to the luminal environment and induce expression of neuron-specific effector mechanisms. Neuron-specific deletion of Ahr or constitutive overexpression of its negative feedback regulator CYP1A1, results in reduced peristaltic activity of the colon, similar to that observed in microbiota-depleted mice. Finally, expression of Ahr in enteric neurons of antibiotic-treated mice partially restores intestinal motility. Taken together, our experiments identify AhR signalling in enteric neurons as a regulatory node that integrates the luminal environment with the physiological output of intestinal neural circuits towards gut homeostasis and health. The enteric nervous system (ENS) encompasses the intrinsic neural networks of the gastrointestinal (GI) tract, which regulate most aspects of intestinal physiology, including peristalsis. In addition to host-specific genetic programmes, microbiota and diet have emerged as critical regulators of gut tissue physiology and changes in the microbial composition of the lumen often accompany GI disorders. We found that gut environmental sensor Aryl hydrocarbon receptor (AhR) is induced in colonic neurons in response to microbiota colonisation and regulates intestinal peristalsis in an AhR ligand-dependent manner. In this experiment, we used RNA sequencing to identify genes regulated in mouse colonic neurons by AhR activation.
Project description:Transcriptional profiling of mouse jejunal epithelia comparing Tcrbd-/-, DAOwt/wt mouse and Tcrbd-/-, DAOG181R/G181R Intestinal microbiota produce D-amino acids, which are bacteria-specific metabolites, for regulation of bacterial cell wall integrity. Host intestine releases D-amino acid oxidase (DAO) to degrade bacterial D-amino acids, which shapes gut microbial community. However, it is not clarified whether bacterial D-amino acids affect host s immunity. In the present study, we compared mRNA expression in ileal epithelial tissue of DAO null mice with that of control mice in the absence of both T cell receptor beta and delta (Tcrb/d). Transcriptome analysis revealed up-regulation of inflammatory cytokines such as TNFa, IL1b, and IFNg in the epithelial tissue. Up-regulation of such cytokines could promote survival of na ve B cells and increase IgA-producing plasma cells, which in turn results in enhancement of IgA production. These results indicate that DAO controls intestinal immune responses through regulation of na ve B cells and differentiation of mature B cells.
Project description:Metabolic programs and host defense are highly integrated to ensure proper immune responses during stress. Central to these responses, mTOR regulates immune functions by sensing and integrating environmental cues, yet how these systems are coordinated at the intestinal surface remains undefined. We show that the antimicrobial peptide α-defensin is functionally sustained during nutrient deprivation due to regulation of defensin-processing enzyme MMP7 by microbiota- and host-derived factors. Unlike other antimicrobial peptides, the MMP7-α-defensin axis remains active during nutrient fluctuations, providing essential protection against enteric pathogens. Sustained Mmp7 expression requires the microbiota and is mediated by de-repression of the transcription activator Atoh1 upon attenuation of the transcriptional repressor Hes1 in intestinal epithelial cells. Hes1 levels are regulated via mTOR and controlled translationally, constituting a metabolism-translation-transcription loop. Disrupting this loop by supplying nutrients paradoxically compromises anti-bacterial defense. Together, these results uncover a regulatory circuit that couples host nutrient status to epithelial anti-microbial immunity.
Project description:Circadian rhythmicity is a defining feature of mammalian metabolism that synchronizes metabolic processes to day-night light cycles. Here, we show that the intestinal microbiota programs diurnal metabolic rhythms in the mouse small intestine through histone deacetylase 3 (HDAC3). The microbiota induced expression of intestinal epithelial HDAC3, which was recruited rhythmically to chromatin and produced synchronized diurnal oscillations in histone acetylation, metabolic gene expression, and nutrient uptake. HDAC3 also functioned non-canonically to coactivate estrogen related receptor a (ERRa), inducing microbiota-dependent rhythmic transcription of the lipid transporter gene Cd36 and promoting lipid absorption and diet-induced obesity. Our findings reveal that HDAC3 integrates microbial and circadian cues to regulate diurnal metabolic rhythms, and pinpoint a key mechanism by which the microbiota controls host metabolism.
Project description:Enterococcus faecalis is a natural inhabitant of the human gastrointestinal tract. In a healthy physiological state of the gut (eubiosis), E. faecalis is a subdominant species in the intestinal microbiota. When the intestinal homeostasis is disrupted (dysbiosis), it becomes dominant species and can cause infections. The taurocholate bile acid (TCA) becomes prominent during dysbiosis. This experiment aimed to better understand how E. faecalis adapts to TCA. We showed that TCA reprograms genes involved in the pool management of amino acids and nucleotides.
Project description:Despite the importance of amino acids as basic components of proteins, amino acids also serve as substrates for multiple other metabolic pathways, such as the TCA cycle that regulates energy homeostasis. The response to deficiency in the biosynthesis of specific amino acids (also termed âamino acid starvationâ) has been studied extensively in yeast (See for example Petti et. al., 2011 Survival of starving yeast is correlated with oxidative stress response and non-respiratory mitochondria function. Proc. Natl. Acad. Sci. USA 108: 1089-1098). In contrast, very little is known about the metabolic responses to deficiency in the biosynthesis of amino acids in plants. A number of recent reports have already shown that catabolism of amino acids can significantly contribute to cellular energy homeostasis particularly during the nighttime and particularly in response to stress. In the present manuscript we used a previously characterized Arabidopsis mutant with reduced expression of the Lys biosynthesis enzyme L,L-diaminopimelate aminotransferase (dapat) to investigate the physiological and metabolic impacts of deficient Lys biosynthesis. The results obtained demonstrate that not stomatal limitations but rather biochemical alterations are responsible for the decreased photosynthesis and growth of the dapat mutants which mimic stress conditions associated to Lys deficiency. Our findings suggest that manipulation of Lys biosynthesis in dapat mutant simulates a stress response culminating in a highly exquisite metabolic reprogramming such that alternative substrates support energy generation once carbohydrate metabolism is down-regulated.