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Gut Microbes

Katerina V-A Johnson, Philip W J Burnet
Studies on microbiome diversity are flooding the current literature, yet lessons from ecology clearly demonstrate that diversity is just one factor to consider when analyzing an ecosystem, along with its stability, structure and function. Measures of diversity may be a useful tool for interpreting metagenomic data but the question remains as to how informative they are and what insight they may provide into the state of the microbiome. A study utilizing mathematical modelling to investigate the ecological dynamics of microbial communities has shown that diversity and stability may not always be concomitant...
October 10, 2016: Gut Microbes
Ilaria Spadoni, Alessandro Pietrelli, Graziano Pesole, Maria Rescigno
It has been widely demonstrated that tolerance against gut microbiota is compartmentalized to mucosal sites where microbes mostly reside. How the commensal bacteria are excluded from the entrance into the blood stream via intestinal capillaries that are located beneath the gut epithelium was not clear. We recently described the existence of a new anatomical structure, the 'gut vascular barrier' (GVB), both in murine and human intestines that plays a fundamental role in avoiding indiscriminate trafficking of bacteria from the gut into the blood circulation...
October 10, 2016: Gut Microbes
Derrick M Chu, Kristen M Meyer, Amanda L Prince, Kjersti M Aagaard
Evidence supporting the Developmental Origins of Health and Disease Hypothesis indicates that maternal nutrition in pregnancy has a significant impact on offspring disease risk later in life, likely by modulating developmental processes in utero. Gut microbiota have recently been explored as a potential mediating factor, as dietary components strongly influence microbiota abundance, function and its impact on host physiology. A growing body of evidence has additionally indicated that the intrauterine environment is not sterile as once presumed, indicating that maternal-fetal transmission of microbiota may occur during pregnancy...
September 29, 2016: Gut Microbes
Roi Avraham, Deborah T Hung
The interface between immune cells and intracellular bacterial pathogens produces complex, diverse interactions. During individual encounters, highly adaptable and dynamic host cells and bacteria vary in their responses, thereby contributing to well-documented heterogeneous outcomes of infection. The challenge now is to break down the multidimensionality of these interactions into informative readouts of population physiology and predictors of responses to infection. We recently reported one approach to this challenge that couples single cell RNA-seq analysis with fluorescent markers to characterize infection phenotype...
September 22, 2016: Gut Microbes
Christina S Faherty, Tao Wu, Carolyn R Morris, Christen L Grassel, David A Rasko, Jill M Harper, Terez Shea-Donohue, Alessio Fasano, Eileen M Barry
Shigella flexneri is a Gram-negative pathogen that invades the colonic epithelium and causes millions of cases of watery diarrhea or bacillary dysentery predominately in children under the age of 5 years in developing countries. The effector Shigella enterotoxin 2 (ShET2), or OspD3, is encoded by the sen or ospD3 gene on the virulence plasmid. Previous literature has suggested that ospD3 is in an operon downstream of the ospC1 gene, and expression of both genes is controlled by a promoter upstream of ospC1...
September 22, 2016: Gut Microbes
Mariana Martins, Constance Porrini, Laurence du Merle, Camille Danne, Catherine Robbe-Masselot, Patrick Trieu-Cuot, Shaynoor Dramsi
Streptococcus gallolyticus is a commensal bacterium responsible for infectious endocarditis in the elderly, which has frequently been associated with colonic carcinoma. Whether this species is a cause or a consequence of colorectal cancer remains unknown. We recently demonstrated that S. gallolyticus Pil3 pilus is required for adhesion to colonic mucus and for colonization of mouse distal colon. We show here that Pil3 pilus binds equally well to human colonic mucins derived from HT29-MTX cells and to human stomach mucins from healthy donors...
September 22, 2016: Gut Microbes
Naoki Harada, Ryo Hanaoka, Kazuki Hanada, Takeshi Izawa, Hiroshi Inui, Ryoichi Yamaji
Low testosterone levels increase the risk for cardiovascular disease in men and lead to shorter life spans. Our recent study showed that androgen deprivation via castration altered fecal microbiota and exacerbated risk factors for cardiovascular disease, including obesity, impaired fasting glucose, excess hepatic triglyceride accumulation, and thigh muscle weight loss in high-fat diet (HFD)-fed male mice. However, when mice were administered antibiotics that disrupted the gut microbiota, castration did not increase cardiovascular risks or decrease the ratio of dried feces to food intake...
September 22, 2016: Gut Microbes
Sushma Kommineni, Christopher J Kristich, Nita H Salzman
Recently, our laboratory demonstrated that bacteriocins produced by commensal enterococci provide an advantage in niche maintenance in the highly competitive environment of the gastrointestinal (GI) tract (1) . Bacterial production of bacteriocins is a conserved defense strategy to help establish an ecological niche (2, 3) . Bacteriocin-encoding genes in enterococci are often carried on mobile genetic elements, including conjugative plasmids, enabling the transfer of such traits to other community members in a shared niche...
September 13, 2016: Gut Microbes
Angela B Javurek, William G Spollen, Sarah A Johnson, Nathan J Bivens, Karen H Bromert, Scott A Givan, Cheryl S Rosenfeld
Gut dysbiosis may result in various diseases, such as metabolic and neurobehavioral disorders. Exposure to endocrine disrupting chemicals (EDCs), including bisphenol A (BPA) and ethinyl estradiol (EE), especially during development, may also increase the risk for such disorders. An unexplored possibility is that EDC-exposure might alter the gut microbial composition. Gut flora and their products may thus be mediating factors for the disease-causing effects of these chemicals. To examine the effects of EDCs on the gut microbiome, female and male monogamous and biparental California mice (Peromyscus californicus) were exposed to BPA (50 mg/kg feed weight) or EE (0...
September 13, 2016: Gut Microbes
Rosita Rigoni, Fabio Grassi, Anna Villa, Barbara Cassani
Hypomorphic Rag mutations in humans cause Omenn Syndrome (OS) a severe immunodeficiency associated with autoimmune-like manifestations mediated by oligoclonal activated T and B cells. The clinical and immunological spectrum of OS presentation is extremely broad. However, the role played by environmental triggers in the disease pathogenesis remains largely unknown. We have recently shown in a murine model that gut microbiota has a substantial role in determining the distinctive immune dysregulation of OS. Here, we describe how dysbiosis and loss of T cell tolerance to commensals influence the expression of autoimmunity at the barrier site and beyond, and the disease hallmark hyper-IgE...
August 30, 2016: Gut Microbes
Aonghus Lavelle, Grainne Lennon, Desmond C Winter, P Ronan O'Connell
The relevance of biogeography to the distal gut microbiota has been investigated in both health and inflammatory bowel disease (IBD), however multiple factors, including sample type and methodology, microbiota characterization and interpersonal variability make the construction of a core model of colonic biogeography challenging. In addition, how phylogenetic classification relates to immunogenicity and whether consistent alterations in the microbiota are associated with ulcerative colitis (UC) remain open questions...
September 2, 2016: Gut Microbes
Natalia Zeber-Lubecka, Maria Kulecka, Filip Ambrozkiewicz, Agnieszka Paziewska, Krzysztof Goryca, Jakub Karczmarski, Tymon Rubel, Wojciech Wojtowicz, Piotr Mlynarz, Lukasz Marczak, Roman Tomecki, Michal Mikula, Jerzy Ostrowski
Irritable bowel syndrome (IBS) is a chronic functional disorder and its development may be linked, directly and indirectly, to intestinal dysbiosis. Here we investigated the interactions between IBS symptoms and the gut microbiome, including the relation to rifaximin (1200 mg daily; 11.2 g per a treatment). We recruited 72 patients, including 31 with IBS-D (diarrhea), 11 with IBS-C (constipation), and 30 with IBS-M (mixed constipation and diarrhea) and 30 healthy controls (HCs). Of them, 68%, 64%, and 53% patients with IBS-D, IBS-C, and IBS-M, respectively, achieved 10-12 week-term improvement after the rifaximin treatment...
September 2, 2016: Gut Microbes
Richard C Laughlin, Robert C Alaniz
Characterization of host microbial interactions typically occurs on the cellular or protein level. Recently, a more thorough and accurate appreciation of cellular interactions has come into better focus with improved understanding of membrane vesicles (OMV). While OMVs are documented primarily in Gram-negative bacteria, certain Gram-positive species generate these structures, despite the obvious physical limitations of the cell envelope. Here, we briefly review the current understanding of OMVs in content and function, their role in pathogenesis, and the consequences of somatic cell gene expression on these events...
September 2, 2016: Gut Microbes
Frédéric Raymond, Maxime Déraspe, Maurice Boissinot, Michel G Bergeron, Jacques Corbeil
Antibiotics profoundly affect the gut microbiome and modulate microbial communities. We recently observed that antimicrobial drugs also impact the abundance and distribution of antibiotic resistance genes. In this addendum, we reanalyze our ∼1 trillion nucleotide shotgun metagenomic dataset to quantify comprehensive genomic differences at the sequence level before and after antibiotic treatment. We show that 7 day exposure to cefprozil leads to a statistically significant loss of metagenome sequences. Recovery of gut microbiomes 3 months after antibiotherapy was characterized by the emergence of new genome sequences not observed prior to antibiotic exposure...
September 2, 2016: Gut Microbes
Hans Raskov, Jakob Burcharth, Hans-Christian Pommergaard, Jacob Rosenberg
Irritable bowel syndrome is a common functional gastrointestinal disorder and it is now evident that irritable bowel syndrome is a multi-factorial complex of changes in microbiota and immunology. The bidirectional neurohumoral integrated communication between the microbiota and the autonomous nervous system is called the gut-brain-axis, which integrates brain and GI functions, such as gut motility, appetite and weight. The gut-brain-axis has a central function in the perpetuation of irritable bowel syndrome and the microbiota plays a critical role...
September 2, 2016: Gut Microbes
Andrew J Gasparrini, Terence S Crofts, Molly K Gibson, Phillip I Tarr, Barbara B Warner, Gautam Dantas
The gut microbiota plays important roles in nutrient absorption, immune system development, and pathogen colonization resistance. Perturbations early in life may be detrimental to host health in the short and the long-term. Antibiotics are among the many factors that influence the development of the microbiota. Because antibiotics are heavily administered during the first critical years of gut microbiota development, it is important to understand the effects of these interventions. Infants, particularly those born prematurely, represent an interesting population because they receive early and often extensive antibiotic therapy in the first months after birth...
September 2, 2016: Gut Microbes
Rachael J Rigby, Jacquelyn Carr, Kelly Orgel, Stephanie L King, P Kay Lund, Christopher M Dekaney
Doxorubicin (DOXO) induces significant, but transient, increases in apoptosis in the stem cell zone of the jejunum, followed by mucosal damage involving a decrease in crypt proliferation, crypt number, and villus height. The gastrointestinal tract is home to a vast population of commensal bacteria and numerous studies have demonstrated a symbiotic relationship between intestinal bacteria and intestinal epithelial cells (IEC) in maintaining homeostatic functions of the intestine. However, whether enteric bacteria play a role in DOXO-induced damage is not well understood...
September 2, 2016: Gut Microbes
Jiffin K Paulose, Vincent M Cassone
Circadian clocks are fundamental properties of all eukaryotic organisms and at least some prokaryotic organisms. Recent studies in our laboratory have shown that the gastrointestinal system contains a circadian clock that controls many, if not all, aspects of gastrointestinal function. We now report that at least one species of intestinal bacteria, Enterobacter aerogenes, responds to the pineal and gastrointestinal hormone melatonin by an increase in swarming activity. This swarming behavior is expressed rhythmically, with a period of approximately 24 hrs...
September 2, 2016: Gut Microbes
Rajesh Shah, Julia L Cope, Dorottya Nagy-Szakal, Scot Dowd, James Versalovic, Emily B Hollister, Richard Kellermayer
Inflammatory bowel diseases (IBD) are chronic intestinal inflammatory disorders characterized by a complex disruption of the physiologic interaction between the host immune system and intestinal microbes precipitated by environmental factors. Numerous observations indicate the altered composition and function of the intestinal microbiome of patients with ulcerative colitis (UC), a subtype of IBD. The accuracy of these results may be limited by confounding factors, such as concurrent medication use. To address these limitations, we examined the colonic mucosal microbiome of pediatric patients with UC prior to initiating treatment...
September 2, 2016: Gut Microbes
Elin Org, Margarete Mehrabian, Brian W Parks, Petia Shipkova, Xiaoqin Liu, Thomas A Drake, Aldons J Lusis
We previously reported quantitation of gut microbiota in a panel of 89 different inbred strains of mice, and we now examine the question of sex differences in microbiota composition. When the total population of 689 mice was examined together, several taxa exhibited significant differences in abundance between sexes but a larger number of differences were observed at the single strain level, suggesting that sex differences can be obscured by host genetics and environmental factors. We also examined a subset of mice on chow and high fat diets and observed sex-by-diet interactions...
June 29, 2016: Gut Microbes
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