Project description:EMG produced TPA metagenomics assembly of the Dissecting effects of community context on a gut pathobiont in a model of childhood undernutrition (Host-pathobiont-microbiota interactions in undernutrition) data set.
Project description:Constitution of a biobank of tissues, whole blood and plasma samples and stools to identify markers associated with treatment response, postoperative morbidity including neuro-cognitive and mood complications and prognosis of Inflammatory Bowel disease or colorectal cancer.
Project description:The gastrointestinal tract harbors a diverse microbiota that has coevolved with mammalian hosts. Though most associations are symbiotic or commensal, some resident bacteria (termed pathobionts) have the potential to cause disease. Bacterial type VI secretion systems (T6SSs) are one mechanism for forging host-microbial interactions. Here we reveal a protective role for the T6SS of Helicobacter hepaticus, a Gram-negative bacterium of the intestinal microbiota. H. hepaticus mutants with a defective T6SS display increased numbers within intestinal epithelial cells (IECs) and during intestinal colonization. Remarkably, the T6SS directs an anti-inflammatory gene expression profile in IECs, and CD4+ T cells from mice colonized with T6SS mutants produce increased interleukin-17 in response to IECs presenting H. hepaticus antigens. Thus, the H. hepaticus T6SS limits colonization and intestinal inflammation, promoting a balanced relationship with the host. We propose that disruption of such balances contributes to human disorders such as inflammatory bowel disease and colon cancer.
Project description:In utero undernutrition is associated with obesity and insulin resistance, although its effect on skeletal muscle remains poorly defined. We report that, in mice, adult offspring from undernourished dams have decreased energy expenditure, decreased skeletal muscle mitochondrial content, and altered energetics in isolated mitochondria and permeabilized muscle fibers. Strikingly, when these mice are put on a 40% calorie restricted diet they lose half as much weight as calorie restricted controls. Our results reveal for the first time that in utero undernutrition alters metabolic physiology having a profound effect on skeletal muscle energetics and response to calorie restriction in adulthood.
Project description:The mammalian gastrointestinal tract harbors a diverse microbiota residing in intimate contact with the host immune system. Though most associations are symbiotic or commensal, some resident bacteria (termed pathobionts) have the potential to induce disease in immunocompromised hosts. Type VI secretion systems (T6SSs) have recently emerged as a novel mechanism for forging microbial-host interactions during infection. We reveal here a unique protective role for the T6SS of Helicobacter hepaticus, a Gram-negative bacterium of the murine intestinal microbiota. The T6SS of H. hepaticus targets effector substrates to intestinal epithelial cells (IECs). Mutants in T6SSs display higher intracellular and cell-associated numbers upon incubation with IECs, and exhibit increased bacterial colonization of the gastrointestinal tract compared to wild-type bacteria. The T6SS accordingly directs an anti-inflammatory gene expression profile in IECs co-cultured with H. hepaticus. Remarkably, T6SS mutants induce an exacerbated pro-inflammatory response in an experimental model of colitis. CD4+ T cells isolated from T6SS mutant-colonized animals produce increased T-helper 17 (Th17) cytokines in response to IECs presenting H. hepaticus antigens. These data demonstrate that H. hepaticus intimately interacts with IECs and employs type VI secretion to establish a balanced host relationship by limiting microbial colonization and intestinal inflammation. We propose that altering host-bacterial equilibriums that lead to dysbiosis of the microbiota contributes to human disorders such as inflammatory bowel disease and colon cancer.
Project description:Maternal caloric restriction during the last week of gestation resulted in low birth weight (LBW) and increased risk of LBW-associated metabolic diseases in adult life. The metabolic phenotypes transmitted to F2 generation by paternal manner without additional altered nutrition. To investigate the mechanism of this intergenerational inheritance, two Cohorts were exposed to different magnitudes of undernutrition both in utero during the last week of gestation and/or postnatal until weaning. We performed MeDIP-seq on the genomic DNA from sperm collected from these mice.
Project description:1H NMR metabolomics was performed on urine samples weekly and on plasma and liver samples collected at week 4 from these animals, to identify metabolites that respond to protein undernutrition. To further investigate metabolites which were fluctuated in response to protein undernutrition in terms of metabolic enzymes, hepatic mRNA microarray and quantitative PCR analyses were also performed at week 4.
Project description:In utero undernutrition is associated with obesity and insulin resistance, although its effect on skeletal muscle remains poorly defined. We report that, in mice, adult offspring from undernourished dams have decreased energy expenditure, decreased skeletal muscle mitochondrial content, and altered energetics in isolated mitochondria and permeabilized muscle fibers. Strikingly, when these mice are put on a 40% calorie restricted diet they lose half as much weight as calorie restricted controls. Our results reveal for the first time that in utero undernutrition alters metabolic physiology having a profound effect on skeletal muscle energetics and response to calorie restriction in adulthood. We have used a mouse model of low birth weight generated through 50% food restriction of mouse dams during the third week of gestation. We have studied in utero food restricted offspring and control offspring that were not food restricted in utero in both the ad libitum and calorie restricted states. Gene expression profiling was performed on tibialis anterior muscle from 8 mice per group, pooled in pairs.
Project description:Child undernutrition is a global health issue associated with a high burden of infectious disease. Undernourished children display an overabundance of intestinal pathogens and pathobionts, and these bacteria induce enteric dysfunction in undernourished mice; however, the cause of their overgrowth remains poorly defined. Here, we show that disease-inducing human isolates of Enterobacteriaceae and Bacteroidales spp. are capable of multi-species symbiotic cross-feeding, resulting in synergistic growth of a mixed community in vitro. Growth synergy occurs uniquely under malnourished conditions limited in protein and iron: in this context, Bacteroidales spp. liberate diet- and mucin-derived sugars and Enterobacteriaceae spp. enhance the bioavailability of iron. Analysis of human microbiota datasets reveals that Bacteroidaceae and Enterobacteriaceae are strongly correlated in undernourished children, but not in adequately nourished children, consistent with a diet-dependent growth synergy in the human gut. Together these data suggest that dietary cross-feeding fuels the overgrowth of pathobionts in undernutrition.
Project description:To model how interactions among enteropathogens and gut microbial community members contribute to undernutrition, we colonized gnotobiotic mice fed representative Bangladeshi diets with sequenced bacterial strains cultured from the fecal microbiota of two 24-month-old Bangladeshi children: one healthy and the other underweight. The undernourished donor's bacterial collection contained an enterotoxigenic Bacteroides fragilis strain (ETBF), whereas the healthy donor's bacterial collection contained two nontoxigenic strains of B. fragilis (NTBF). Analyses of mice harboring either the unmanipulated culture collections or systematically manipulated versions revealed that ETBF was causally related to weight loss in the context of its native community but not when introduced into the healthy donor's community. This phenotype was transmissible from the dams to their offspring and was associated with derangements in host energy metabolism manifested by impaired tricarboxylic acid cycle activity and decreased acyl-coenzyme A utilization. NTBF reduced ETBF's expression of its enterotoxin and mitigated the effects of ETBF on the transcriptomes of other healthy donor community members. These results illustrate how intraspecific (ETBF-NTBF) and interspecific interactions influence the effects of harboring B. fragilis.