Risultati per: GUT

Stroke, Volume 54, Issue Suppl_1, Page ATP238-ATP238, February 1, 2023. We currently evaluated the effect of focal cerebral ischemia on gut virome and bacteriome in adult mice. Adult male C57BL/6 mice were subjected to transient middle cerebral artery occlusion or sham surgery. Virome and bacteriome were analyzed using shotgun metagenomics in the fecal samples collected from each mouse before and at 24h of reperfusion. Bioinformatics tools including VIBRANT (v1.2.1), DIAMOND Blastp (v0.9.14.115), VConTACT2 (v0.9.5), Cytoscape (v3.7.2), mash (v2.0), MUMmer (v3.1), Samtools (v1.11), DESeq2 (v1.28.1), MetaWRAP, and CRISPR Recognition Tool (v1.2) were used to assess viral networks, viral auxiliary metabolic genes, and viral protein network changes. Bacteriome was analyzed by kneaddata v0.7.2, MetaPhlAn version 2.7.7, and humann2 v2.8.1. Focal ischemia induced significant differences in fecal viral and bacterial taxa at the strain levels compared with sham. Furthermore, viral protein networks altered significantly after stroke. In particular, the clusters of Clostridia-like phages and Erysipelatoclostridiaceae phages showed a differential association between stroke and sham. In addition, we identified a significant reduction in the phages and bacteria of Lactobacillus after stroke. These studies indicate a possible viral-bacterial correlative change in the gut after stroke.

Stroke, Volume 54, Issue Suppl_1, Page A20-A20, February 1, 2023. Introduction:Neonatal Hypoxic Ischemic Encephalopathy (nHIE) is a leading cause of infant mortality and morbidity worldwide. Males are at greater risk than females, and survivors of nHIE suffer from major disability with limited therapeutic options. Growing clinical and pre-clinical evidence shows neurological injury adversely alters the microbial populations in the gut (dysbiosis) and depletes anti-inflammatory metabolites exclusively made by the gut microbiota. Replacing key microbially-derived beneficial metabolites improves cognitive outcomes in pre-clinical models of adult stroke. However, changes in the gut microbiota and its metabolites after nHIE have not been explored and may lay the foundation for future therapies.Hypothesis:nHIE leads to gut dysbiosis and reduces microbial-derived metabolites, which worsens neurological outcomes in males and females.Methods:A modified Rice Vannucci Model on PND9 C57BL/6 mice was used to model nHIE. Fecal, plasma, gut, and brain samples were collected acutely (24hrs) and chronically (7wks) after injury.Results:We found a significant decrease in 3-indolepropionic acid (p=0.0190, n=4-6), inoxyl-3-sulfate (p=0.0098, n=4-6) and indoxyl acetate (p=0.0096, n=4-6) in the plasma of male mice 24hrs after HIE compared to sham controls, with no significant changes in female plasma. There was a significant increase in indole metabolites in the ischemic hemisphere in both males and females 24hrs after HIE. 7wks after nHIE, there was a significant increase in anxiety-like behavior in males (decrease in % of time immobile during tail suspension=0.018, n=6) and decreased functional ability (nest building score p=0.0147, n=6) in males with HIE compared to sham controls. No significant changes were observed in females. 16S rRNA sequencing data showed dysbiotic microbiota composition after nHIE, consistent with the microbial-metabolite changes found by mass spectroscopy analysis.Conclusion:nHIE induced brain injury results in gut dysbiosis, with sex-specific alterations in circulating indole metabolites and behavioral deficits. This supports our hypothesis that a sex-specific reduction in bioavailability of microbial-metabolites worsens CNS damage after nHIE.

Introduction
Chronic cytomegalovirus (CMV) infection is very frequent in people living with HIV (PLWH). High anti-CMV IgG titres, which may be linked to transient CMV replication, have been associated with earlier mortality, CD8 T-cell expansion, lower CD4/CD8 ratio and increased T-cell senescence. We previously showed that anti-CMV IgG titres correlated with gut permeability in PLWH on antiretroviral therapy (ART), which was associated with microbial translocation, systemic inflammation and non-infectious/non-AIDS comorbidities. Letermovir, a novel anti-CMV drug with a good safety profile, was recently approved for anti-CMV prophylaxis in allogeneic haematopoietic stem cell transplant recipients. A drastic and selective reduction of both low-grade replication and clinically significant CMV infections, combined with an improved immune reconstitution have been reported. In vitro, letermovir prevented CMV-induced epithelial disruption in intestinal tissues. Based on these findings, we aim to assess whether letermovir could inhibit CMV subclinical replication in CMV-seropositive PLWH receiving ART and, in turn, decrease CMV-associated gut damage and inflammation.

Method and analysis
We will conduct a multi-centre, open-label, randomised, controlled clinical trial, including a total of 60 CMV-seropositive ART-treated PLWH for at least 3 years, with a viral load 400 cells/µL. Forty participants will be randomised to receive letermovir for 14 weeks and 20 participants will receive standard of care (ART) alone. Plasma, pheripheral blood mononuclear cells (PBMCs), and stool samples will be collected. Colon biopsies will be collected in an optional substudy. We will assess the effect of letermovir on gut damage, microbial translocation, inflammation and HIV reservoir size.

Ethics and dissemination
The study was approved by Health Canada and the Research Ethics Boards of the McGill University Health Centre (MUHC-REB, protocol number: MP37-2022-8295). Results will be made available through publications in open access peer-reviewed journals and through the CIHR/CTN website.

Trial registration number
NCT05362916.

At least in mice, gut microbes affect the brain’s reward center during exercise.

This study, using the database from the Rome Foundation Global Epidemiology Survey, aimed to assess the differences in quality of life overall, and by age and sex, across individual disorders of gut-brain interaction (DGBI), gastrointestinal anatomical region(s), and number of overlapping DGBI.

Objective
Idiopathic Parkinson’s disease (PD) is characterised by alpha-synuclein (aSyn) aggregation and death of dopaminergic neurons in the midbrain. Recent evidence posits that PD may initiate in the gut by microbes or their toxins that promote chronic gut inflammation that will ultimately impact the brain. In this work, we sought to demonstrate that the effects of the microbial toxin β-N-methylamino-L-alanine (BMAA) in the gut may trigger some PD cases, which is especially worrying as this toxin is present in certain foods but not routinely monitored by public health authorities.

Design
To test the hypothesis, we treated wild-type mice, primary neuronal cultures, cell lines and isolated mitochondria with BMAA, and analysed its impact on gut microbiota composition, barrier permeability, inflammation and aSyn aggregation as well as in brain inflammation, dopaminergic neuronal loss and motor behaviour. To further examine the key role of mitochondria, we also determined the specific effects of BMAA on mitochondrial function and on inflammasome activation.

Results
BMAA induced extensive depletion of segmented filamentous bacteria (SFB) that regulate gut immunity, thus triggering gut dysbiosis, immune cell migration, increased intestinal inflammation, loss of barrier integrity and caudo-rostral progression of aSyn. Additionally, BMAA induced in vitro and in vivo mitochondrial dysfunction with cardiolipin exposure and consequent activation of neuronal innate immunity. These events primed neuroinflammation, dopaminergic neuronal loss and motor deficits.

Conclusion
Taken together, our results demonstrate that chronic exposure to dietary BMAA can trigger a chain of events that recapitulate the evolution of the PD pathology from the gut to the brain, which is consistent with ‘gut-first’ PD.

Accumulating evidence indicates that gut transit time is a key factor in shaping the gut microbiota composition and activity, which are linked to human health. Both population-wide and small-scale studies have identified transit time as a top covariate contributing to the large interindividual variation in the faecal microbiota composition. Despite this, transit time is still rarely being considered in the field of the human gut microbiome. Here, we review the latest research describing how and why whole gut and segmental transit times vary substantially between and within individuals, and how variations in gut transit time impact the gut microbiota composition, diversity and metabolism. Furthermore, we discuss the mechanisms by which the gut microbiota may causally affect gut motility. We argue that by taking into account the interindividual and intraindividual differences in gut transit time, we can advance our understanding of diet–microbiota interactions and disease-related microbiome signatures, since these may often be confounded by transient or persistent alterations in transit time. Altogether, a better understanding of the complex, bidirectional interactions between the gut microbiota and transit time is required to better understand gut microbiome variations in health and disease.

The GI tract faces a great challenge as it needs to organise nutrient uptake while at the same time prevent toxic substances and harmful organisms from entering the host. To execute this complex task, the intestinal wall is endowed with a myriad of cell types (muscle, neurons, glia, interstitial cells, endocrine, immune and epithelial cells, and vasculature) that have to work in concert. These cells are meticulously organised in concentric layers, within which the enteric nervous system (ENS) controls gut motility, blood flow and secretion.1 Scattered throughout these layers, especially in the lamina propria, are different immune cells that constitute the prime line of defence. The ENS consists of glia and different populations of neurons that communicate like any other nervous system via synaptic contacts. The enteric presynaptic terminals contain mitochondria and a host of presynaptic proteins necessary for synaptic neurotransmitter release. As part of their synaptic…

From the stinging words of disappointment from his attending physician, an internal medicine physician in this narrative medicine essay tells how that moment of bare truth altered him and suggests that medical students may fare better from blunt but kind corrective conversations.

Objective
Fetal growth restriction (FGR) is a devastating pregnancy complication that increases the risk of perinatal mortality and morbidity. This study aims to determine the combined and relative effects of genetic and intrauterine environments on neonatal microbial communities and to explore selective FGR-induced gut microbiota disruption, metabolic profile disturbances and possible outcomes.

Design
We profiled and compared the gut microbial colonisation of 150 pairs of twin neonates who were classified into four groups based on their chorionicity and discordance of fetal birth weight. Gut microbiota dysbiosis and faecal metabolic alterations were determined by 16S ribosomal RNA and metagenomic sequencing and metabolomics, and the long-term effects were explored by surveys of physical and neurocognitive development conducted after 2~3 years of follow-up.

Results
Adverse intrauterine environmental factors related to selective FGR dominate genetics in their effects of elevating bacterial diversity and altering the composition of early-life gut microbiota, and this effect is positively related to the severity of selective FGR in twins. The influence of genetic factors on gut microbes diminishes in the context of selective FGR. Gut microbiota dysbiosis in twin neonates with selective FGR and faecal metabolic alterations features decreased abundances of Enterococcus and Acinetobacter and downregulated methionine and cysteine levels. Correlation analysis indicates that the faecal cysteine level in early life is positively correlated with the physical and neurocognitive development of infants.

Conclusion
Dysbiotic microbiota profiles and pronounced metabolic alterations are associated with selective FGR affected by adverse intrauterine environments, emphasising the possible effects of dysbiosis on long-term neurobehavioural development.

Objective
Cigarette smoking is a major risk factor for colorectal cancer (CRC). We aimed to investigate whether cigarette smoke promotes CRC by altering the gut microbiota and related metabolites.

Design
Azoxymethane-treated C57BL/6 mice were exposed to cigarette smoke or clean air 2 hours per day for 28 weeks. Shotgun metagenomic sequencing and liquid chromatography mass spectrometry were parallelly performed on mice stools to investigate alterations in microbiota and metabolites. Germ-free mice were transplanted with stools from smoke-exposed and smoke-free control mice.

Results
Mice exposed to cigarette smoke had significantly increased tumour incidence and cellular proliferation compared with smoke-free control mice. Gut microbial dysbiosis was observed in smoke-exposed mice with significant differential abundance of bacterial species including the enrichment of Eggerthella lenta and depletion of Parabacteroides distasonis and Lactobacillus spp. Metabolomic analysis showed increased bile acid metabolites, especially taurodeoxycholic acid (TDCA) in the colon of smoke-exposed mice. We found that E. lenta had the most positive correlation with TDCA in smoke-exposed mice. Moreover, smoke-exposed mice manifested enhanced oncogenic MAPK/ERK (mitogen-activated protein kinase/extracellular signal-regulated protein kinase 1/2) signalling (a downstream target of TDCA) and impaired gut barrier function. Furthermore, germ-free mice transplanted with stools from smoke-exposed mice (GF-AOMS) had increased colonocyte proliferation. Similarly, GF-AOMS showed increased abundances of gut E. lenta and TDCA, activated MAPK/ERK pathway and impaired gut barrier in colonic epithelium.

Conclusion
The gut microbiota dysbiosis induced by cigarette smoke plays a protumourigenic role in CRC. The smoke-induced gut microbiota dysbiosis altered gut metabolites and impaired gut barrier function, which could activate oncogenic MAPK/ERK signalling in colonic epithelium.

Objectives
Gut microbiota is a key component in obesity and type 2 diabetes, yet mechanisms and metabolites central to this interaction remain unclear. We examined the human gut microbiome’s functional composition in healthy metabolic state and the most severe states of obesity and type 2 diabetes within the MetaCardis cohort. We focused on the role of B vitamins and B7/B8 biotin for regulation of host metabolic state, as these vitamins influence both microbial function and host metabolism and inflammation.

Design
We performed metagenomic analyses in 1545 subjects from the MetaCardis cohorts and different murine experiments, including germ-free and antibiotic treated animals, faecal microbiota transfer, bariatric surgery and supplementation with biotin and prebiotics in mice.

Results
Severe obesity is associated with an absolute deficiency in bacterial biotin producers and transporters, whose abundances correlate with host metabolic and inflammatory phenotypes. We found suboptimal circulating biotin levels in severe obesity and altered expression of biotin-associated genes in human adipose tissue. In mice, the absence or depletion of gut microbiota by antibiotics confirmed the microbial contribution to host biotin levels. Bariatric surgery, which improves metabolism and inflammation, associates with increased bacterial biotin producers and improved host systemic biotin in humans and mice. Finally, supplementing high-fat diet-fed mice with fructo-oligosaccharides and biotin improves not only the microbiome diversity, but also the potential of bacterial production of biotin and B vitamins, while limiting weight gain and glycaemic deterioration.

Conclusion
Strategies combining biotin and prebiotic supplementation could help prevent the deterioration of metabolic states in severe obesity.

Trial registration number
NCT02059538.

Obesity is a key player in the current global health crisis, acting as a leading risk factor in the main causes of morbidity and mortality, ranging from cardiovascular disease (CVD) and type 2 diabetes (T2D) to respiratory illnesses.1 While unhealthy diets and sedentary lifestyles together with polygenetic risks represent major causes of obesity, recent studies suggest that the gut microbiota also plays a part.2 A large body of evidence has revealed alterations in the gut microbiota composition and function of obese subjects compared with healthy controls.3–5 Moreover, certain prospective observational and interventional studies have identified microbiome signatures that precede the onset of obesity6 7 or influence the response to diet.8 Notwithstanding, precise identification of microbiome biomarkers is difficult due to the large interindividual variability of the microbiota as well as of the host…