Project description:The gut-brain axis allows gut microbes to influence host social behavior, yet the specific role of microbial genetic variation in this process and its potential transgenerational effects remains poorly understood. Using C. elegans as a model, we identified 77 E. coli strains among 3,983 mutants that markedly enhanced C. elegans aggregation behavior. Our findings reveal that mutant bacteria modulate C. elegans social behavior through distinct neurobehavioral pathways, demonstrating a synergistic regulatory mechanism between microbial genetics and host heredity. Mechanistically, ycgJ mutant bacteria were found to impact C. elegans social behavior via the mitochondrial pathway. Additionally, even F2 offspring of parent C. elegans exposed to these mutant bacteria exhibited enhanced social behavior within their populations. These insights underscore the significance of investigating microbial genetic variation in relation to host behavior, particularly for the development of genetically engineered probiotics, aimed at promoting well-being across generations.
Project description:Here we use appropriate taxon-specific models along with support from independent cohorts to show association between human host genotype and gut microbiome variation. Using fecal derived 16S rRNA gene sequences and host genotype data from the Flemish Gut Flora Project (FGFP) we identify genetic associations involving multiple microbial traits. Mendelian randomization analysis was able to estimate associations between microbial traits and disease, however in the absence of clear microbiome driven effects, caution is needed in interpretation. This work marks a growing catalog of genetic associations which will provide insight into the contribution of host genotype to gut microbiome. Despite this, the uncertain origin of association signals will likely complicate future work looking to dissect function or use associations for causal inference analysis.
Project description:The gut microbiota impacts many aspects of host biology including immune function. One hypothesis is that microbial communities induce epigenetic changes with accompanying alterations in chromatin accessibility, providing a mechanism that allows a community to have sustained host effects even in the face of its structural or functional variation. We used ATAC-seq to define chromatin accessibility in predicted enhancer regions of intestinal αβ+ and γδ+ intraepithelial lymphocytes (IELs) purified from germ-free mice, their conventionally-raised (CONV-R) counterparts, and mice reared GF and then colonized with a CONV-R gut microbiota at the end of the suckling-weaning transition. Characterizing genes adjacent to traditional enhancers and super-enhancers revealed signaling networks, metabolic pathways, and enhancer-associated transcription factors affected by the microbiota. Our results support the notion that epigenetic modifications help define microbial community-affiliated functional features of host immune cell lineages.
Project description:The gut microbiome is significantly altered in inflammatory bowel diseases, but the basis of these changes is not well understood. We have combined metagenomic and metatranscriptomic profiling of the gut microbiome to assess changes to both bacterial community structure and transcriptional activity in a mouse model of colitis. Gene families involved in microbial resistance to oxidative stress, including Dps/ferritin, Fe-dependent peroxidase and glutathione S-transferase, were transcriptionally up-regulated in colitis, implicating a role for increased oxygen tension in gut microbiota modulation. Transcriptional profiling of the host gut tissue and host RNA in the gut lumen revealed a marked increase in the transcription of genes with an activated macrophage and granulocyte signature, suggesting the involvement of these cell types in influencing microbial gene expression. Down-regulation of host glycosylation genes further supports a role for inflammation-driven changes to the gut niche that may impact the microbiome. We propose that members of the bacterial community react to inflammation-associated increased oxygen tension by inducing genes involved in oxidative stress resistance. Furthermore, correlated transcriptional responses between host glycosylation and bacterial glycan utilisation support a role for altered usage of host-derived carbohydrates in colitis. Complementary transcription profiling data from the mouse hosts have also been deposited at ArrayExpress under accession number E-MTAB-3590 ( http://www.ebi.ac.uk/arrayexpress/experiments/E-MTAB-3590/ ).
Project description:The gut microbiome has been implicated in multiple human chronic gastrointestinal (GI) disorders. Determining its mechanistic role in disease pathogenesis has been difficult due to the apparent disconnect between animal and human studies and a lack of an integrated multi-omics view in the context of disease-specific physiological changes. We integrated longitudinal multi-omics data from the gut microbiome, metabolome, host epigenome and transcriptome in the context of irritable bowel syndrome (IBS) host physiology. We identified IBS subtype-specific and symptom-related variation in microbial composition and function. A subset of identified changes in microbial metabolites correspond to host physiological mechanisms that are relevant to IBS. By integrating multiple data layers, we identified purine metabolism as a novel host-microbial metabolic pathway in IBS with translational potential. Our study highlights the importance of longitudinal sampling and integrating complementary multi-omics data to identify functional mechanisms that can serve as therapeutic targets in a comprehensive treatment strategy for chronic GI diseases.
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:The gut microbiome is significantly altered in inflammatory bowel diseases, but the basis of these changes is not well understood. We have combined metagenomic and metatranscriptomic profiling of the gut microbiome to assess changes to both bacterial community structure and transcriptional activity in a mouse model of colitis. Gene families involved in microbial resistance to oxidative stress, including Dps/ferritin, Fe-dependent peroxidase and glutathione S-transferase, were transcriptionally up-regulated in colitis, implicating a role for increased oxygen tension in gut microbiota modulation. Transcriptional profiling of the host gut tissue and host RNA in the gut lumen revealed a marked increase in the transcription of genes with an activated macrophage and granulocyte signature, suggesting the involvement of these cell types in influencing microbial gene expression. Down-regulation of host glycosylation genes further supports a role for inflammation-driven changes to the gut niche that may impact the microbiome. We propose that members of the bacterial community react to inflammation-associated increased oxygen tension by inducing genes involved in oxidative stress resistance. Furthermore, correlated transcriptional responses between host glycosylation and bacterial glycan utilisation support a role for altered usage of host-derived carbohydrates in colitis. Complementary RNA-seq and DNA-seq data sets of the microbiome from this study have also been deposited at ArrayExpress under accession number E-MTAB-3562 ( http://www.ebi.ac.uk/arrayexpress/experiments/E-MTAB-3562/ ).
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:The interrelationships between our diets and the structure and operations of our gut microbial communities are poorly understood. A model microbial community of ten sequenced human gut bacteria was introduced into gnotobiotic mice and changes in the abundance of each species were measured in response to randomized perturbations of four defined ingredients in the host diet. From the responses, we developed a statistical model that predicted over 50% of the variation in species abundance in response to the diet perturbations and were able to identify which factors in the diet best explained the changes seen for each community member. The community’s transcriptional response was driven by the absolute abundance of each species, as diet ingredient concentrations were not associated with significant changes in the transcription of individual community members.