| 1. |
- Ahmed, Hany, et al.
(författare)
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Microbiota-derived metabolites as drivers of gut–brain communication
- 2022
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Ingår i: Gut Microbes. - : Informa UK Limited. - 1949-0984 .- 1949-0976. ; 14:1
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Forskningsöversikt (refereegranskat)abstract
- Alterations in the gut microbiota composition have been associated with a range of neurodevelopmental, neurodegenerative, and neuropsychiatric disorders. The gut microbes transform and metabolize dietary- and host-derived molecules generating a diverse group of metabolites with local and systemic effects. The bi-directional communication between brain and the microbes residing in the gut, the so-called gut–brain axis, consists of a network of immunological, neuronal, and endocrine signaling pathways. Although the full variety of mechanisms of the gut–brain crosstalk is yet to be established, the existing data demonstrates that a single metabolite or its derivatives are likely among the key inductors within the gut–brain axis communication. However, more research is needed to understand the molecular mechanisms underlying how gut microbiota associated metabolites alter brain functions, and to examine if different interventional approaches targeting the gut microbiota could be used in prevention and treatment of neurological disorders, as reviewed herein. Abbreviations:4-EPS 4-ethylphenylsulfate; 5-AVA(B) 5-aminovaleric acid (betaine); Aβ Amyloid beta protein; AhR Aryl hydrocarbon receptor; ASD Autism spectrum disorder; BBB Blood–brain barrier; BDNF Brain-derived neurotrophic factor; CNS Central nervous system; GABA ɣ-aminobutyric acid; GF Germ-free; MIA Maternal immune activation; SCFA Short-chain fatty acid; 3M-4-TMAB 3-methyl-4-(trimethylammonio)butanoate; 4-TMAP 4-(trimethylammonio)pentanoate; TMA(O) Trimethylamine(-N-oxide); TUDCA Tauroursodeoxycholic acid; ZO Zonula occludens proteins.
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| 4. |
- Arvidsson, Ida, et al.
(författare)
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Apyrase decreases phage induction and Shiga toxin release from E. coli O157:H7 and has a protective effect during infection
- 2022
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Ingår i: Gut microbes. - : Informa UK Limited. - 1949-0976 .- 1949-0984. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Shiga toxin (Stx)-producing enterohemorrhagic Escherichia coli (EHEC) cause gastrointestinal infection and, in severe cases, hemolytic uremic syndrome which may lead to death. There is, to-date, no therapy for this infection. Stx induces ATP release from host cells and ATP signaling mediates its cytotoxic effects. Apyrase cleaves and neutralizes ATP and its effect on Stx and EHEC infection was therefore investigated. Apyrase decreased bacterial RecA and dose-dependently decreased toxin release from E. coli O157:H7 in vitro, demonstrated by reduced phage DNA and protein levels. The effect was investigated in a mouse model of E. coli O157:H7 infection. BALB/c mice infected with Stx2-producing E. coli O157:H7 were treated with apyrase intraperitoneally, on days 0 and 2 post-infection, and monitored for 11 days. Apyrase-treated mice developed disease two days later than untreated mice. Untreated infected mice lost significantly more weight than those treated with apyrase. Apyrase-treated mice exhibited less colonic goblet cell depletion and apoptotic cells, as well as lower fecal ATP and Stx2, compared to untreated mice. Apyrase also decreased platelet aggregation induced by co-incubation of human platelet-rich-plasma with Stx2 and E. coli O157 lipopolysaccharide in the presence of collagen. Thus, apyrase had multiple protective effects, reducing RecA levels, stx2 and toxin release from EHEC, reducing fecal Stx2 and protecting mouse intestinal cells, as well as decreasing platelet activation, and could thereby delay the development of disease.
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| 5. |
- Basic, M., et al.
(författare)
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Approaches to discern if microbiome associations reflect causation in metabolic and immune disorders
- 2022
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Ingår i: Gut Microbes. - : Informa UK Limited. - 1949-0976 .- 1949-0984. ; 14:1
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Forskningsöversikt (refereegranskat)abstract
- Our understanding of microorganisms residing within our gut and their roles in the host metabolism and immunity advanced greatly over the past 20 years. Currently, microbiome studies are shifting from association and correlation studies to studies demonstrating causality of identified microbiome signatures and identification of molecular mechanisms underlying these interactions. This transformation is crucial for the efficient translation into clinical application and development of targeted strategies to beneficially modulate the intestinal microbiota. As mechanistic studies are still quite challenging to perform in humans, the causal role of microbiota is frequently evaluated in animal models that need to be appropriately selected. Here, we provide a comprehensive overview on approaches that can be applied in addressing causality of host-microbe interactions in five major animal model organisms (Caenorhabditis elegans, Drosophila melanogaster, zebrafish, rodents, and pigs). We particularly focused on discussing methods available for studying the causality ranging from the usage of gut microbiota transfer, diverse models of metabolic and immune perturbations involving nutritional and chemical factors, gene modifications and surgically induced models, metabolite profiling up to culture-based approached. Furthermore, we addressed the impact of the gut morphology, physiology as well as diet on the microbiota composition in various models and resulting species specificities. Finally, we conclude this review with the discussion on models that can be applied to study the causal role of the gut microbiota in the context of metabolic syndrome and host immunity. We hope this review will facilitate important considerations for appropriate animal model selection.
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| 6. |
- Begum, Neelu, et al.
(författare)
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Host-mycobiome metabolic interactions in health and disease
- 2022
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Ingår i: Gut microbes. - : Informa UK Limited. - 1949-0976 .- 1949-0984. ; 14:1
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Forskningsöversikt (refereegranskat)abstract
- Fungal communities (mycobiome) have an important role in sustaining the resilience of complex microbial communities and maintenance of homeostasis. The mycobiome remains relatively unexplored compared to the bacteriome despite increasing evidence highlighting their contribution to host-microbiome interactions in health and disease. Despite being a small proportion of the total species, fungi constitute a large proportion of the biomass within the human microbiome and thus serve as a potential target for metabolic reprogramming in pathogenesis and disease mechanism. Metabolites produced by fungi shape host niches, induce immune tolerance and changes in their levels prelude changes associated with metabolic diseases and cancer. Given the complexity of microbial interactions, studying the metabolic interplay of the mycobiome with both host and microbiome is a demanding but crucial task. However, genome-scale modelling and synthetic biology can provide an integrative platform that allows elucidation of the multifaceted interactions between mycobiome, microbiome and host. The inferences gained from understanding mycobiome interplay with other organisms can delineate the key role of the mycobiome in pathophysiology and reveal its role in human disease.
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| 7. |
- Bielig, Harald, et al.
(författare)
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A role for quorum sensing in regulating innate immune responses mediated by Vibrio cholerae outer membrane vesicles (OMVs)
- 2011
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Ingår i: Gut microbes. - : Taylor & Francis. - 1949-0976 .- 1949-0984. ; 2:5, s. 274-279
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Tidskriftsartikel (refereegranskat)abstract
- Outer membrane vesicles (OMVs) are released from many Gram-negative bacteria. OMVs interact with and are taken up by human cells. We and others have now showed that OMVs contain peptidoglycan, which is sensed mainly by the pattern-recognition receptor NOD1 in the cytoplasm of host cells. Vibrio cholerae is clinically important as one of the causative agents of severe dehydrating diarrhea in humans. We showed that non-O1 non-O139 V. cholerae (NOVC) strains of V. cholera produce OMVs. Of note, we revealed that NOVC can evade NOD1-mediated immune surveillance by the quorum sensing machinery. Here we review these recent findings and discuss the relevance for our understanding of bacterial infections and innate immune responses.
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| 8. |
- Birchenough, George M. H., et al.
(författare)
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Dietary destabilisation of the balance between the microbiota and the colonic mucus barrier
- 2019
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Ingår i: Gut microbes. - : Informa UK Limited. - 1949-0984 .- 1949-0976. ; 10:2, s. 246-250
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Tidskriftsartikel (refereegranskat)abstract
- It has long been acknowledged that dietary fibres are important to maintain a healthy gut. Over the past decade, several studies have shown that loss of complex polysaccharides from the Western diet has resulted in alterations to our colonic microbiota. The concurrent increase in the incidence of inflammatory bowel disease in the Western world has driven us to explore the potential mechanistic link between diet, the microbiota and the host defence systems that normally prevent inflammation. Using mice fed a low fibre Western-style diet and robust live tissue analytical methods we have now provided evidence that this diet impairs the colonic inner mucus layer that normally separates bacteria from host cells. Western societies urgently need to develop their understanding of the molecular mechanisms of the diet-microbiota-mucus axis and its implications for inflammatory diseases.
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| 9. |
- Butt, Julia, et al.
(författare)
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Association of Pre-diagnostic Antibody Responses to Escherichia coli and Bacteroides fragilis Toxin Proteins with Colorectal Cancer in a European Cohort
- 2021
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Ingår i: Gut microbes. - : Taylor & Francis. - 1949-0976 .- 1949-0984. ; 13:1, s. e1903825-1-e1903825-14
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Tidskriftsartikel (refereegranskat)abstract
- Experimental evidence has implicated genotoxic Escherichia coli (E. coli) and enterotoxigenic Bacteroides fragilis (ETBF) in the development of colorectal cancer (CRC). However, evidence from epidemiological studies is sparse. We therefore assessed the association of serological markers of E. coli and ETBF exposure with odds of developing CRC in the European Prospective Investigation into Nutrition and Cancer (EPIC) study. Serum samples of incident CRC cases and matched controls (n = 442 pairs) were analyzed for immunoglobulin (Ig) A and G antibody responses to seven E. coli proteins and two isoforms of the ETBF toxin via multiplex serology. Multivariable-adjusted conditional logistic regression analyses were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association of sero-positivity to E. coli and ETBF with CRC. The IgA-positivity of any of the tested E. coli antigens was associated with higher odds of developing CRC (OR: 1.42; 95% CI: 1.05–1.91). Dual-positivity for both IgA and IgG to E. coli and ETBF was associated with >1.7-fold higher odds of developing CRC, with a significant association only for IgG (OR: 1.75; 95% CI: 1.04, 2.94). This association was more pronounced when restricted to the proximal colon cancers (OR: 2.62; 95% CI: 1.09, 6.29) compared to those of the distal colon (OR: 1.24; 95% CI: 0.51, 3.00) (pheterogeneity = 0.095). Sero-positivity to E. coli and ETBF was associated with CRC development, suggesting that co-infection of these bacterial species may contribute to colorectal carcinogenesis. These findings warrant further exploration in larger prospective studies and within different population groups.
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| 10. |
- de Groot, P. F., et al.
(författare)
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Fecal microbiota transplantation in metabolic syndrome: History, present and future
- 2017
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Ingår i: Gut Microbes. - : Informa UK Limited. - 1949-0976 .- 1949-0984. ; 8:3, s. 253-267
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Tidskriftsartikel (refereegranskat)abstract
- The history of fecal microbiota transplantation (FMT) dates back even to ancient China. Recently, scientific studies have been looking into FMT as a promising treatment of various diseases, while in the process teaching us about the interaction between the human host and its resident microbial communities. Current research focuses mainly on Clostridium difficile infections, however interest is rising in other areas such as inflammatory bowel disease (IBD) and the metabolic syndrome. With regard to the latter, the intestinal microbiota might be causally related to the progression of insulin resistance and diabetes. FMT in metabolic syndrome has proven to be an intriguing method to study the role of the gut microbiota and open the way to new therapies by dissecting in whom insulin resistance is driven by microbiota. In this article we review the history of FMT, the present evidence on its role in the pathophysiology of metabolic syndrome and its efficacy, limitations and future prospects. © 2017 The Author(s). Published with license by Taylor & Francis © 2017, © P. F. de Groot, M. N. Frissen, N. C. de Clercq, and M. Nieuwdorp.
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