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Gut Microbes

Christopher John Kiely, Paul Pavli, Claire Louise O'Brien
Studies of the human intestinal microbiome in patients with inflammatory bowel disease (IBD) consistently show that there are differences (an abnormal or unbalanced microbiome, "dysbiosis") when compared to healthy subjects. We sought to describe changes in the microbiome in individual patients over time, and determine the clinical factors that are associated with significant alteration. Forty-two mucosal biopsies were collected from 20 patients that were spaced an average of 2.4 years apart. These were analysed using bacterial 16S rRNA gene high-throughput sequencing methods...
March 15, 2018: Gut Microbes
Allison M Weis, Raymond Soto, June L Round
The commensal microbiota influences many aspects of immune system regulation, including T cells, but molecular details of how this occurs are largely unknown. Here we review our findings that the microbiota regulates Erdr1, a secreted apoptotic factor, to control T cell survival. Erdr1 is highly upregulated in CD4+ T cells from germfree mice and antibiotic treated animals, and our study shows that Erdr1 is suppressed by the microbiota via Toll-like receptor signaling and MyD88 dependent pathways. Erdr1 functions in an autocrine fashion and promotes apoptosis through the FAS/FASL pathway...
March 15, 2018: Gut Microbes
Efrat L Amitay, Agne Krilaviciute, Hermann Brenner
Colorectal cancer (CRC) is a leading cause of cancer morbidity and mortality. Dysbiosis in the gut microbiota may be associated with CRC. This systematic review focuses on differences in gut microbial community between people diagnosed with CRC or adenoma and healthy individuals using fecal samples, emphasizing non-invasive fecal microbiome models for CRC early diagnosis. Nineteen studies were identified in a systematic literature search of Pubmed, Web of Science and ScienceDirect. Several bacteria were reported to differ in abundance between CRC and adenoma cases and healthy controls, with Fusobacterium the most common...
March 15, 2018: Gut Microbes
Quintin Borgersen, David T Bolick, Glynis L Kolling, Matthew Aijuka, Fernando Ruiz-Perez, Richard L Guerrant, James P Nataro, Araceli E Santiago
Enteroaggregative E. coli (EAEC) is associated with food-borne outbreaks of diarrhea and growth faltering among children in developing countries. A Shiga toxin-producing EAEC strain of serotype O104:H4 strain caused one of the largest outbreaks of a food-borne infection in Europe in 2011. The outbreak was traced to contaminated fenugreek sprouts, yet the mechanisms whereby such persistent contamination of sprouts could have occurred are not clear. We found that under ambient conditions of temperature and in minimal media, pathogenic Shiga toxin-producing EAEC O104:H4 227-11 and non-Shiga toxin-producing 042 strains both produce high levels of exopolysaccharide structures (EPS) that are released to the external milieu...
March 15, 2018: Gut Microbes
Williams Turpin, Larbi Bedrani, Osvaldo Espin-Garcia, Wei Xu, Mark S Silverberg, Michelle I Smith, David S Guttman, Anne Griffiths, Paul Moayyedi, Remo Panaccione, Hien Huynh, Hillary Steinhart, Guy Aumais, Konstantin Shestopaloff, Levinus A Dieleman, Dan Turner, Andrew D Paterson, Kenneth Croitoru
Heritability analysis of the microbiota has demonstrated the importance of host genotype in defining the human microbiota. The alpha (1,2)-fucosyltransferase 2 encoded by FUT2 is involved in the formation of the H antigen and the SNP, rs601338 is associated with ABO histo-blood group antigen secretion in the intestinal mucosa. Previous studies have provided non replicated results for the association of this polymorphism with the composition and inferred function of intestinal microbiota. We aimed to assess this relationship in a large cohort of 1,190 healthy individuals...
March 13, 2018: Gut Microbes
Joseph P Zackular, Eric P Skaar
Clostridium difficile in one of the most commonly reported nosocomial pathogens worldwide. Beyond antibiotic use, little is known about the host, microbiota, and environmental factors that contribute to susceptibility to and severity of C. difficile infection (CDI). We recently observed that in a mouse model of CDI, excess dietary zinc (Zn) alters the gut microbiota and decreases resistance to CDI. Moreover, we determined that high levels of Zn exacerbate C. difficile-associated disease and calprotectin-mediated Zn limitation is an essential host response to infection...
March 13, 2018: Gut Microbes
Markus Arnoldini, Jonas Cremer, Terence Hwa
The human gut microbiota is highly dynamic, and the host has a strong influence on its composition. In our recent study, we integrated new quantitative measurements on bacterial growth physiology with a reanalysis of published data on human physiology to build a comprehensive modeling framework to generate predictions of how changes in different host factors influence microbiota composition. We show that hydrodynamics forces in the colon, along with colonic water absorption that manifests as transit time, exert a major impact on microbiota density and composition through their effect on colonic pH which directly affects microbiota competition for food...
March 13, 2018: Gut Microbes
Tomasz Cieplak, Nitzan Soffer, Alexander Sulakvelidze, Dennis Sandris Nielsen
Antibiotics offer an efficient means for managing diseases caused by bacterial pathogens. However, antibiotics are typically broad spectrum and they can indiscriminately kill beneficial microbes in body habitats such as the gut, deleteriously affecting the commensal gut microbiota. In addition, many bacteria have developed or are developing resistance to antibiotics, which complicates treatment and creates significant challenges in clinical medicine. Therefore, there is a real and urgent medical need to develop alternative antimicrobial approaches that will kill specific problem-causing bacteria without disturbing a normal, and often beneficial, gut microbiota...
March 8, 2018: Gut Microbes
Tasha Barr, Suhas Sureshchandra, Paul Ruegger, Jingfei Zhang, Wenxiu Ma, James Borneman, Kathleen Grant, Ilhem Messaoudi
Alcohol use disorder (AUD) results in increased intestinal permeability, nutrient malabsorption, and increased risk of colorectal cancer (CRC). Our understanding of the mechanisms underlying these morbidities remains limited because studies to date have relied almost exclusively on short-term heavy/binge drinking rodent models and colonic biopsies/fecal samples collected from AUD subjects with alcoholic liver disease (ALD). Consequently, the dose- and site-dependent impact of chronic alcohol consumption in the absence of overt liver disease remains poorly understood...
March 8, 2018: Gut Microbes
Ganesan Velmurugan
The advent of industrial revolution caused a large inflow of synthetic chemicals for medical, agricultural, industrial and other purposes in the world. In general, these chemicals were subjected to toxicological risk assessment for human health and ecology before release for public use. But today we are witnessing a negative impact of some of these chemicals on human health and environment indicating an underestimation of toxic effects by current risk assessment protocol. Recent studies established gut microbiota as one of the key player in intercession of toxicity of drugs and synthetic chemicals...
March 6, 2018: Gut Microbes
Gwladys Sevrin, Sébastien Massier, Benoit Chassaing, Allison Agus, Julien Delmas, Jérémy Denizot, Elisabeth Billard, Nicolas Barnich
The pathogenesis of Crohn's disease (CD) is multifactorial and involves genetic susceptibility, environmental triggers and intestinal microbiota. Adherent-invasive Escherichia coli (AIEC) are flagellated bacteria more prevalent in CD patients than in healthy subjects and promote chronic intestinal inflammation. We aim at deciphering the role of flagella and flagellin modulation by intestinal conditions. AIEC flagellum expression is required for optimal adhesion to and invasion of intestinal epithelial cells...
March 1, 2018: Gut Microbes
Sabine Kienesberger, Guillermo I Perez-Perez, Asalia Z Olivares, Pradip Bardhan, Shafiqul A Sarker, Kh Zahid Hasan, R Bradley Sack, Martin J Blaser
Helicobacter pylori colonization is prevalent throughout the world, and is predominantly acquired during childhood. In developing countries, >70% of adult populations are colonized with H. pylori and >50% of children become colonized before the age of 10 years. However, the exact timing of acquisition is unknown. We assessed detection of H. pylori acquisition among a birth cohort of 105 children in Mirzapur, Bangladesh. Blood samples collected at time 0 (cord blood), and at 6, 12, 18, and 24 months of life were examined for the presence of IgG and IgA antibodies to whole cell H...
March 1, 2018: Gut Microbes
Shermel Sherman, Nadeen Sarsour, Marziyeh Salehi, Allen Schroering, Blair Mell, Bina Joe, Jennifer W Hill
BACKGROUND: Conditions of excess androgen in women, such as polycystic ovary syndrome (PCOS), often exhibit intergenerational transmission. One way in which the risk for PCOS may be increased in daughters of affected women is through exposure to elevated androgens in utero. Hyperandrogenemic conditions have serious health consequences, including increased risk for hypertension and cardiovascular disease. Recently, gut dysbiosis has been found to induce hypertension in rats, such that blood pressure can be normalized through fecal microbial transplant...
February 22, 2018: Gut Microbes
Emilie Viennois, Benoit Chassaing
The intestinal tract is inhabited by a large and diverse community of bacteria, collectively referred to as the gut microbiota. Composed of 500-1000 distinct species, the intestinal microbiota plays an important role in immunity and metabolism. However, alterations in its composition are associated with a variety of inflammatory diseases including obesity, diabetes, and inflammatory bowel disease (IBD). Among many other factors, our diet impacts microbiota composition and function, in either beneficial or detrimental ways...
February 13, 2018: Gut Microbes
Sheldon Rowan, Allen Taylor
Age-related macular degeneration (AMD) is a leading cause of blindness world-wide. Although the etiology of AMD is multifactorial, diet and nutrition have strong epidemiologic associations with disease onset and progression. Recent studies indicate a role for gut microbiota in development of AMD in mouse models and in some forms of human AMD. We previously found that consuming lower glycemia diets is associated with protection against AMD in humans and switching from higher to lower glycemia diets arrests AMD phenotypes in mice...
February 12, 2018: Gut Microbes
Burkhardt Flemer, Maeve Herlihy, Micheal O'Riordain, Fergus Shanahan, Paul W O'Toole
In a recent study1 we reported that tissue-associated microbial Co-abundance Groups (CAGs) were differentially associated with CRC. Two of the CAGs, which we named Pathogen CAG and Prevotella CAG, were correlated with a gene expression signature indicative of a TH17 response. A TH17 response has been associated with decreased survival in patients with CRC2, and members of the Pathogen CAG such as Fusobacterium nucleatum, Escherichia coli and Bacteroides fragilis have been repeatedly reported to be associated with CRC-development...
February 8, 2018: Gut Microbes
Natacha Colliou, Yong Ge, Minghao Gong, Mojgan Zadeh, Jing Li, Francis Alonzo, Mansour Mohamadzadeh
Regulation of Th17 and Th1 cell responses against intracellular pathogens, including Listeria monocytogenes (L. m), is critical to limit inflammation-induced tissue damage. We recently demonstrated the ability of P. UF1 bacterium derived from the intestinal bacterial commensals of preterm infants fed human breast milk to significantly mitigate pathogen-induced inflammation limiting colonic tissue damage. Here we further elucidated the potential of P. UF1 to also regulate innate and T cells, particularly Th17 and Th1 cells, against systemic L...
February 8, 2018: Gut Microbes
Yolanda Y Huang, Ana Martínez-Del Campo, Emily P Balskus
The discovery of enzymes responsible for previously unappreciated microbial metabolic pathways furthers our understanding of host-microbe and microbe-microbe interactions. We recently identified and characterized a new gut microbial glycyl radical enzyme (GRE) responsible for anaerobic metabolism of trans-4-hydroxy-l-proline (Hyp). Hyp dehydratase (HypD) catalyzes the removal of water from Hyp to generate Δ1-pyrroline-5-carboxylate (P5C). This enzyme is encoded in the genomes of a diverse set of gut anaerobes and is prevalent and abundant in healthy human stool metagenomes...
February 6, 2018: Gut Microbes
Yong-Guo Zhang, Megha Singhal, Zhijie Lin, Christopher Manzella, Anoop Kumar, Waddah A Alrefai, Pradeep K Dudeja, Seema Saksena, Jun Sun, Ravinder K Gill
Salmonella and Citrobacter are gram negative, members of Enterobacteriaceae family that are important causative agents of diarrhea and intestinal inflammation. TGF-β1 is a pleiotropic multifunctional cytokine that has been implicated in modulating the severity of microbial infections. How these pathogens alter the TGF-β1 signaling pathways in the intestine is largely unknown. Streptomycin-pretreated C57BL/6J mouse model colonized with S. typhimurium for 8 hours (acute) and 4 days (chronic) infection and FVB/N mice infected with C...
January 30, 2018: Gut Microbes
Kirsty Brown, D Wade Abbott, Richard R E Uwiera, G Douglas Inglis
The murine cecum is a major site of fermentation of dietary materials, and production of short chain fatty acids (SCFAs). To examine the role that the cecum plays in acute bacterial infection in mice, the cecum was surgically removed, and changes in bacterial communities and production of SCFAs were analyzed relative to surgical sham animals. To incite bacterial colitis, mice were orally challenged with Citrobacter rodentium. The impact of butyrate administered directly into the colon was also examined. Concentrations of SCFAs in feces were substantially lower in mice with an excised cecum...
December 11, 2017: Gut Microbes
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