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1.
Perinatal factors affecting the gut microbiota - are they preventable?
Zietek, M, Szczuko, M, Celewicz, Z, Kordek, A
Ginekologia polska. 2020;(11):709-713
Abstract
Intestinal microbiota affects many aspects of physiological processes. The type of microbiota in the early stages of life is a critical element conditioning the development of the immune response and food tolerance. Disturbed colonization of the digestive tract resulting from the amount or diversity of bacteria colonies stimulates an inflammatory response that is associated in later life with inflammatory and autoimmune diseases. One of the elements disturbing normal colonization in the perinatal period is the operative way of delivery by caesarean section and the administration of antibiotics, used as a prophylactic measure as well as for therapeutic reasons. Based on the current state of knowledge, there is a lot of evidence demonstrating the long-term adverse effects of these modifying agents for gut microbiota, which should be kept to a minimum as far as possible.
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Mechanisms Underlying the Skin-Gut Cross Talk in the Development of IgE-Mediated Food Allergy.
van Splunter, M, Liu, L, van Neerven, RJJ, Wichers, HJ, Hettinga, KA, de Jong, NW
Nutrients. 2020;(12)
Abstract
Immune-globulin E (IgE)-mediated food allergy is characterized by a variety of clinical entities within the gastrointestinal tract, skin and lungs, and systemically as anaphylaxis. The default response to food antigens, which is antigen specific immune tolerance, requires exposure to the antigen and is already initiated during pregnancy. After birth, tolerance is mostly acquired in the gut after oral ingestion of dietary proteins, whilst exposure to these same proteins via the skin, especially when it is inflamed and has a disrupted barrier, can lead to allergic sensitization. The crosstalk between the skin and the gut, which is involved in the induction of food allergy, is still incompletely understood. In this review, we will focus on mechanisms underlying allergic sensitization (to food antigens) via the skin, leading to gastrointestinal inflammation, and the development of IgE-mediated food allergy. Better understanding of these processes will eventually help to develop new preventive and therapeutic strategies in children.
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3.
Human behavior, not race or geography, is the strongest predictor of microbial succession in the gut bacteriome of infants.
Quin, C, Gibson, DL
Gut microbes. 2020;(5):1143-1171
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Abstract
Colonization of the gastrointestinal tract with microorganisms during infancy represents a critical control point for shaping life-long immune-mediated disease susceptibility. Abnormal colonization or an imbalance of microbes, termed dysbiosis, is implicated in several diseases. Consequently, recent research has aimed at understanding ways to manipulate a dysbiotic microbiome during infancy to resemble a normal, healthy microbiome. However, one of the fundamental issues in microbiome research is characterizing what a "normal" infant microbiome is based on geography, ethnicity and cultural variations. This review provides a comprehensive account of what is currently known about the infant microbiome from a global context. In general, this review shows that the influence of cultural variations in feeding practices, delivery modes and hygiene are the biggest contributors to microbial variability. Despite geography or race, all humans have similar microbial succession during infancy.
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4.
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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Role of the Gut Microbiota in Atopic Dermatitis: A Systematic Review.
Petersen, EBM, Skov, L, Thyssen, JP, Jensen, P
Acta dermato-venereologica. 2019;(1):5-11
Abstract
The immune mechanisms involved in atopic dermatitis (AD) are complex and little is known about the possible role of the gut microbiota in the aetiopathogenesis of AD. A systematic review of the literature was performed according to PRISMA guidelines, and included 44 of 2,199 studies (26 observational and 18 interventional studies). Detection of gut microbiota was performed by either 16s rRNA PCR, or by culture. Observational studies were diverse regarding the age of study participants and the bacterial species investigated. Overall, the results were conflicting with regard to diversity of the gut microbiota, specific bacterial colonization, and subsequent risk of AD. Nearly half of the included interventional studies showed that an altered gut microbial colonization due to use of probiotics had a positive effect on the severity of AD. The remaining studies did not show an effect of probiotics on the severity of AD despite an alteration in the gut microbial composition. The role of the gut microbiome for the onset and severity of pre-existing AD remains controversial.
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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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Effect of probiotics on the occurrence of nutrition absorption capacities in healthy children: a randomized double-blinded placebo-controlled pilot study.
Ballini, A, Gnoni, A, De Vito, D, Dipalma, G, Cantore, S, Gargiulo Isacco, C, Saini, R, Santacroce, L, Topi, S, Scarano, A, et al
European review for medical and pharmacological sciences. 2019;(19):8645-8657
Abstract
OBJECTIVE Recent advances in the translational research showed that dietary nutrients have critical importance to the microbioma balance in the gastrointestinal tract. Therefore, the alteration of the intestinal microbiota in order to achieve, restore, and maintain favorable balance in the ecosystem, and the activity of microorganisms present in the gastrointestinal tract is necessary for the improved health condition of the host. The objective of this translational study was to evaluate, in a pediatric population, the efficacy and safety of prophylactic probiotics for a better nutritional absorption capacity in the view to enhance their overall health and immunity. PATIENTS AND METHODS A total of 40 pediatric patients between the ages of 14 and 18 years were enrolled in the study and divided under two categories (treated/active group and placebo group). Three-time points clinical evaluations were performed: a baseline assessment (Time 0), a second evaluation at 5 weeks after the start of probiotic use (Time 1), and a final evaluation at the timeline after 10 weeks (Time 2). In the initial phase of the study, the recruited subjects underwent a panel of initial T0 clinical tests. For each of the patients, a blood sample was taken in order to evaluate the following biochemical measurements: Vitamin D, Vitamin A, Calcium, Zinc, and Iron. Moreover, an initial nutritional evaluation was carried out through which the nutritionist estimated the body composition of the subject (weight and body mass index), the caloric needs and dietary behaviour of each recruited patient. RESULTS Eligible participants were randomized into placebo (n = 20) or treated/active (n = 20) treatment conditions by random allocation using a computerized random number generator, ensuring all investigators remained blind to the treatment distribution. The data were compared within and between groups using statistical methods. The results confirmed that the probiotic supplementation was effective in increasing the overall blood biomarkers levels of vitamins, calcium, and mineral absorption from baseline to 10 weeks of treatment, compared with the placebo. CONCLUSIONS Probiotics may be suggested as supplements to improve biomarkers serum concentration if administered for a period of at least ≥ 5 weeks. However, further studies are required for optimal recommendations in patient treatment.
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Microbiota and gastrointestinal cancer.
Weng, MT, Chiu, YT, Wei, PY, Chiang, CW, Fang, HL, Wei, SC
Journal of the Formosan Medical Association = Taiwan yi zhi. 2019;:S32-S41
Abstract
Gut microbiota plays important roles in many diseases, including cancer. It may promote carcinogenesis by inducing oxidative stress, genotoxicity, host immune response disturbance, and chronic inflammation. Colorectal cancer, hepatocellular carcinoma, and gastric cancer are the major gastrointestinal tract cancers in Taiwan. The microbiota detected in patients with tubular adenoma and villous/tubulovillous polyps is different from that in healthy controls and patients with hyperplastic polyps. Normalization of the microbiota is observed in patients after colorectal cancer treatment. Furthermore, the liver is exposed to microbiota-associated molecular patterns (MAMPs), bacterial metabolites, and toxins, as it is anatomically connected to the gut via the portal vein. Patients with cirrhosis have significantly higher plasma endotoxin levels than healthy controls. Helicobacter pylori is a well-established risk factor for gastric cancer. Some nitrosating bacteria convert nitrogen compounds in gastric fluid to potentially carcinogenic N-nitroso compounds, which also contribute to gastric cancer development. Growing evidence demonstrates that gut microbiota promotes carcinogenesis. In this review, we discuss the mechanisms and types of microbiota changes involved in these gastrointestinal cancers and the future treatment choices.
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Rethinking Diet to Aid Human-Microbe Symbiosis.
Derrien, M, Veiga, P
Trends in microbiology. 2017;(2):100-112
Abstract
The spread of the Western lifestyle has been accompanied by microbial changes thought to underlie the emergence of chronic, nontransmissible, immune-related diseases. The past decade has seen the unprecedented development of therapies for 'replenishing' the microbiota of sick individuals. However, functional and ecological solutions helping the host and the gut microbiota to cope with the ecological stressors of modern life are still lacking. In this review, we discuss how recent advances in gut microbiome science are leading to the identification of microbe-derived and health-relevant metabolites. These molecules will guide the selection of the next-generation of probiotics and dietary recommendations, which should also take the resident gut microbiota into account, to optimise efficacy. These solutions for maintaining a well-functioning gut ecosystem and promoting good health should be customised, palatable, and as widely accessible as possible.
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Probiotic normalization of Candida albicans in schizophrenia: A randomized, placebo-controlled, longitudinal pilot study.
Severance, EG, Gressitt, KL, Stallings, CR, Katsafanas, E, Schweinfurth, LA, Savage, CLG, Adamos, MB, Sweeney, KM, Origoni, AE, Khushalani, S, et al
Brain, behavior, and immunity. 2017;:41-45
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Abstract
The molecules and pathways of the gut-brain axis represent new targets for developing methods to diagnose and treat psychiatric disorders. Manipulation of the gut microbiome with probiotics may be a therapeutic strategy with the potential to relieve gastrointestinal (GI) comorbidities and improve psychiatric symptoms. Candida albicans and Saccharomyces cerevisiae, commensal yeast species, can be imbalanced in the unhealthy human microbiome, and these fungal exposures were previously found elevated in schizophrenia. In a longitudinal, double-blind, placebo-controlled, pilot investigation of 56 outpatients with schizophrenia, we examined the impact of probiotic treatment on yeast antibody levels, and the relationship between treatment and antibody levels on bowel discomfort and psychiatric symptoms. We found that probiotic treatment significantly reduced C. albicans antibodies over the 14-week study period in males, but not in females. Antibody levels of S. cerevisiae were not altered in either treatment group. The highest levels of bowel discomfort over time occurred in C. albicans-seropositive males receiving the placebo. We observed trends towards improvement in positive psychiatric symptoms in males treated with probiotics who were seronegative for C. albicans. Results from this pilot study hint at an association of C. albicans seropositivity with worse positive psychiatric symptoms, which was confirmed in a larger cohort of 384 males with schizophrenia. In conclusion, the administration of probiotics may help normalize C. albicans antibody levels and C. albicans-associated gut discomfort in many male individuals. Studies with larger sample sizes are warranted to address the role of probiotics in correcting C. albicans-associated psychiatric symptoms.