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1.
Interplay between food and gut microbiota in health and disease.
Danneskiold-Samsøe, NB, Dias de Freitas Queiroz Barros, H, Santos, R, Bicas, JL, Cazarin, CBB, Madsen, L, Kristiansen, K, Pastore, GM, Brix, S, Maróstica Júnior, MR
Food research international (Ottawa, Ont.). 2019;:23-31
Abstract
Numerous microorganisms colonize the human gastrointestinal tract playing pivotal roles in relation to digestion and absorption of dietary components. They biotransform food components and produce metabolites, which in combination with food components shape and modulate the host immune system and metabolic responses. Reciprocally, the diet modulates the composition and functional capacity of the gut microbiota, which subsequently influence host biochemical processes establishing a system of mutual interaction and inter-dependency. Macronutrients, fibers, as well as polyphenols and prebiotics are strong drivers shaping the composition of the gut microbiota. Especially, short-chain fatty acids produced from ingested fibers and tryptophan metabolites are key in modulating host immune responses. Since reciprocal interactions between diet, host, and microbiota are personal, understanding this complex network of interactions calls for novel use of large datasets and the implementation of machine learning algorithms and artificial intelligence. In this review, we aim to provide a base for future investigations of how interactions between food components and gut microbiota may influence or even determine human health and disease.
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2.
Type VI Secretion Systems and the Gut Microbiota.
Coyne, MJ, Comstock, LE
Microbiology spectrum. 2019;(2)
Abstract
The human colonic microbiota is a dense ecosystem comprised of numerous microbes, including bacteria, phage, fungi, archaea, and protozoa, that compete for nutrients and space. Studies are beginning to reveal the antagonistic mechanisms that gut bacteria use to compete with other members of this ecosystem. In the healthy human colon, the majority of the Gram-negative bacteria are of the order Bacteroidales. Proteobacteria, such as Escherichia coli, are numerically fewer but confer important properties to the host, such as colonization resistance. Several enteric pathogens use type VI secretion systems (T6SSs) to antagonize symbiotic gut E. coli, facilitating colonization and disease progression. T6SS loci are also widely distributed in human gut Bacteroidales, which includes three predominant genera: Bacteroides, Parabacteroides, and Prevotella. There are three distinct genetic architectures of T6SS loci among the gut Bacteroidales, termed GA1, GA2, and GA3. GA1 and GA2 T6SS loci are contained on integrative and conjugative elements and are the first T6SS loci shown to be readily transferred in the human gut between numerous species and families of Bacteroidales. In contrast, the GA3 T6SSs are present exclusively in Bacteroides fragilis. There are divergent regions in all three T6SS GAs that contain genes encoding effector and immunity proteins, many of which function by unknown mechanisms. To date, only the GA3 T6SSs have been shown to antagonize bacteria, and they target nearly all gut Bacteroidales species analyzed. This review delves more deeply into properties of the T6SSs of these human gut bacteria and the ecological outcomes of their synthesis in vivo.
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3.
Microbiome 101: Studying, Analyzing, and Interpreting Gut Microbiome Data for Clinicians.
Allaband, C, McDonald, D, Vázquez-Baeza, Y, Minich, JJ, Tripathi, A, Brenner, DA, Loomba, R, Smarr, L, Sandborn, WJ, Schnabl, B, et al
Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association. 2019;(2):218-230
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Abstract
Advances in technical capabilities for reading complex human microbiomes are leading to an explosion of microbiome research, leading in turn to intense interest among clinicians in applying these techniques to their patients. In this review, we discuss the content of the human microbiome, including intersubject and intrasubject variability, considerations of study design including important confounding factors, and different methods in the laboratory and on the computer to read the microbiome and its resulting gene products and metabolites. We highlight several common pitfalls for clinicians, including the expectation that an individual's microbiome will be stable, that diet can induce rapid changes that are large compared with the differences among subjects, that everyone has essentially the same core stool microbiome, and that different laboratory and computational methods will yield essentially the same results. We also highlight the current limitations and future promise of these techniques, with the expectation that an understanding of these considerations will help accelerate the path toward routine clinical application of these techniques developed in research settings.
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4.
Mechanisms controlling hormone secretion in human gut and its relevance to metabolism.
Martin, AM, Sun, EW, Keating, DJ
The Journal of endocrinology. 2019;(1):R1-R15
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Abstract
The homoeostatic regulation of metabolism is highly complex and involves multiple inputs from both the nervous and endocrine systems. The gut is the largest endocrine organ in our body and synthesises and secretes over 20 different hormones from enteroendocrine cells that are dispersed throughout the gut epithelium. These hormones include GLP-1, PYY, GIP, serotonin, and CCK, each of whom play pivotal roles in maintaining energy balance and glucose homeostasis. Some are now the basis of several clinically used glucose-lowering and weight loss therapies. The environment in which these enteroendocrine cells exist is also complex, as they are exposed to numerous physiological inputs including ingested nutrients, circulating factors and metabolites produced from neighbouring gut microbiome. In this review, we examine the diverse means by which gut-derived hormones carry out their metabolic functions through their interactions with different metabolically important organs including the liver, pancreas, adipose tissue and brain. Furthermore, we discuss how nutrients and microbial metabolites affect gut hormone secretion and the mechanisms underlying these interactions.
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Targeting the Gut Microbiota to Treat Cachexia.
Genton, L, Mareschal, J, Charretier, Y, Lazarevic, V, Bindels, LB, Schrenzel, J
Frontiers in cellular and infection microbiology. 2019;:305
Abstract
Cachexia occurs in many chronic diseases and is associated with increased morbidity and mortality. It is treated by nutritional support but often with limited effectiveness, leading to the search of other therapeutic strategies. The modulation of gut microbiota, whether through pro-, pre-, syn- or antibiotics or fecal transplantation, is attracting ever-growing interest in the field of obesity, but could also be an interesting and innovative alternative for treating cachexia. This article reviews the evidence linking the features of malnutrition, as defined by the Global Leadership Initiative on Malnutrition [low body mass index (BMI), unintentional body weight loss, low muscle mass, low appetite, and systemic inflammation] and the gut microbiota in human adults with cachexia-associated diseases, and shows the limitations of the present research in that field with suggestions for future directions.
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Microbes: possible link between modern lifestyle transition and the rise of metabolic syndrome.
Moossavi, S, Bishehsari, F
Obesity reviews : an official journal of the International Association for the Study of Obesity. 2019;(3):407-419
Abstract
The rapid decrease in infectious diseases globally has coincided with an increase in the prevalence of obesity and other components of metabolic syndrome. Insulin resistance is a common feature of metabolic syndrome and can be influenced by genetic and non-genetic/environmental factors. The emergence of metabolic syndrome epidemics over only a few decades suggests a more prominent role of the latter. Changes in our environment and lifestyle have indeed paralleled the rise in metabolic syndrome. Gastrointestinal tract microbiota, the composition of which plays a significant role in host physiology, including metabolism and energy homeostasis, are distinctly different within the context of metabolic syndrome. Among humans, recent lifestyle-related changes could be linked to changes in diversity and composition of 'ancient' microbiota. Given the co-adaptation and co-evolution of microbiota with the immune system over a long period of time, it is plausible that such lifestyle-related microbiota changes could trigger aberrant immune responses, thereby predisposing an individual to a variety of diseases. Here, we review current evidence supporting a role for gut microbiota in the ongoing rise of metabolic syndrome. We conclude that population-level shifts in microbiota can play a mediatory role between lifestyle factors and pathogenesis of insulin resistance and metabolic syndrome.
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Emerging Role of the Gut Microbiome in Nonalcoholic Fatty Liver Disease: From Composition to Function.
Sharpton, SR, Ajmera, V, Loomba, R
Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association. 2019;(2):296-306
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Abstract
The gut microbiome, a diverse microbial community in the gastrointestinal tract, plays a pivotal role in the maintenance of health. The gut microbiome metabolizes dietary and host-derived molecules to produce bioactive metabolites, which have a wide array of effects on host metabolism and immunity. 'Dysbiosis' of the gut microbiome, commonly considered as perturbation of microbiome diversity and composition, has been associated with intestinal and extra-intestinal diseases, including nonalcoholic fatty liver disease (NAFLD). A number of endogenous and exogenous factors, such as nutritional intake and xenobiotic exposure, can alter the gut microbiome. We will review the evolving methods for studying the gut microbiome and how these profiling techniques have been utilized to further our understanding of the gut microbial community composition and functional potential in the clinical spectrum of NAFLD. We will highlight microbiome-host interactions that may contribute to the pathogenesis of NAFLD, with a primary focus on mechanisms related to the metabolic output of the gut microbiome. Finally, we will discuss potential therapeutic implications of the gut microbiome in NAFLD.
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General advice in ultrasound based elastography of pediatric patients.
Dietrich, CF, Ferraioli, G, Sirli, R, Popescu, A, Sporea, I, Pienar, C, Kunze, C, Taut, H, Schrading, S, Bota, S, et al
Medical ultrasonography. 2019;(3):315-326
Abstract
Ultrasound elastography including transient elastography (TE), point shear wave elastography, (pSWE) and two (three)- dimensional shear wave elastography (2D-SWE) have been introduced mainly for the evaluation of the liver. All the techniques are also feasible for the examination of spleen, whereas pSWE and 2D-SWE can be used for the assessment of the pancreas, kidney, gastrointestinal tract and other organs. Strain elastography also plays a role for non-liver applications. The aim of the current report is to highlight unique features and techniques for the elastographic examinations in children and to report initial results in non-liver applications.
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The mechanisms of pharmacokinetic food-drug interactions - A perspective from the UNGAP group.
Koziolek, M, Alcaro, S, Augustijns, P, Basit, AW, Grimm, M, Hens, B, Hoad, CL, Jedamzik, P, Madla, CM, Maliepaard, M, et al
European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences. 2019;:31-59
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Abstract
The simultaneous intake of food and drugs can have a strong impact on drug release, absorption, distribution, metabolism and/or elimination and consequently, on the efficacy and safety of pharmacotherapy. As such, food-drug interactions are one of the main challenges in oral drug administration. Whereas pharmacokinetic (PK) food-drug interactions can have a variety of causes, pharmacodynamic (PD) food-drug interactions occur due to specific pharmacological interactions between a drug and particular drinks or food. In recent years, extensive efforts were made to elucidate the mechanisms that drive pharmacokinetic food-drug interactions. Their occurrence depends mainly on the properties of the drug substance, the formulation and a multitude of physiological factors. Every intake of food or drink changes the physiological conditions in the human gastrointestinal tract. Therefore, a precise understanding of how different foods and drinks affect the processes of drug absorption, distribution, metabolism and/or elimination as well as formulation performance is important in order to be able to predict and avoid such interactions. Furthermore, it must be considered that beverages such as milk, grapefruit juice and alcohol can also lead to specific food-drug interactions. In this regard, the growing use of food supplements and functional food requires urgent attention in oral pharmacotherapy. Recently, a new consortium in Understanding Gastrointestinal Absorption-related Processes (UNGAP) was established through COST, a funding organisation of the European Union supporting translational research across Europe. In this review of the UNGAP Working group "Food-Drug Interface", the different mechanisms that can lead to pharmacokinetic food-drug interactions are discussed and summarised from different expert perspectives.
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10.
New Nutritional and Therapeutical Strategies of NEC.
Teresa, C, Antonella, D, de Ville de Goyet Jean,
Current pediatric reviews. 2019;(2):92-105
Abstract
Necrotizing enterocolitis (NEC) is an acquired severe disease of the digestive system affecting mostly premature babies, possibly fatal and frequently associated to systemic complications. Because of the severity of this condition and the possible long-term consequences on the child's development, many studies have aimed at preventing the occurrence of the primary events at the level of the bowel wall (ischemia and necrosis followed by sepsis) by modifying or manipulating the diet (breast milk versus formula) and/or the feeding pattern (time for initiation after birth, continuous versus bolus feeding, modulation of intake according clinical events). Feeding have been investigated so far in order to prevent NEC. However, currently well-established and shared clinical nutritional practices are not available in preventing NEC. Nutritional and surgical treatments of NEC are instead well defined. In selected cases surgery is a therapeutic option of NEC, requiring sometimes partial intestinal resection responsible for short bowel syndrome. In this paper we will investigate the available options for treating NEC according to the Walsh and Kliegman classification, focusing on feeding practices in managing short bowel syndrome that can complicate NEC. We will also analyze the proposed ways of preventing NEC.