| 1. |
- 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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| 2. |
- Dupont, A., et al.
(författare)
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Age-Dependent Susceptibility to Enteropathogenic Escherichia coli (EPEC) Infection in Mice
- 2016
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Ingår i: Plos Pathogens. - : Public Library of Science (PLoS). - 1553-7366 .- 1553-7374. ; 12:5
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Tidskriftsartikel (refereegranskat)abstract
- Enteropathogenic Escherichia coli (EPEC) represents a major causative agent of infant diarrhea associated with significant morbidity and mortality in developing countries. Although studied extensively in vitro, the investigation of the host-pathogen interaction in vivo has been hampered by the lack of a suitable small animal model. Using RT-PCR and global transcriptome analysis, high throughput 16S rDNA sequencing as well as immunofluorescence and electron microscopy, we characterize the EPEC-host interaction following oral challenge of newborn mice. Spontaneous colonization of the small intestine and colon of neonate mice that lasted until weaning was observed. Intimate attachment to the epithelial plasma membrane and microcolony formation were visualized only in the presence of a functional bundle forming pili (BFP) and type III secretion system (T3SS). Similarly, a T3SS-dependent EPEC-induced innate immune response, mediated via MyD88, TLR5 and TLR9 led to the induction of a distinct set of genes in infected intestinal epithelial cells. Infection-induced alterations of the microbiota composition remained restricted to the postnatal period. Although EPEC colonized the adult intestine in the absence of a competing microbiota, no microcolonies were observed at the small intestinal epithelium. Here, we introduce the first suitable mouse infection model and describe an age-dependent, virulence factor-dependent attachment of EPEC to enterocytes in vivo.
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| 3. |
- Fulde, M., et al.
(författare)
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Neonatal selection by Toll-like receptor 5 influences long-term gut microbiota composition
- 2018
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 560:7719
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Tidskriftsartikel (refereegranskat)abstract
- Alterations in enteric microbiota are associated with several highly prevalent immune-mediated and metabolic diseases(1-3), and experiments involving faecal transplants have indicated that such alterations have a causal role in at least some such conditions(4-6). The postnatal period is particularly critical for the development of microbiota composition, host-microbe interactions and immune homeostasis(7-9). However, the underlying molecular mechanisms of this neonatal priming period have not been defined. Here we report the identification of a host-mediated regulatory circuit of bacterial colonization that acts solely during the early neonatal period but influences life-long microbiota composition. We demonstrate age-dependent expression of the flagellin receptor Toll-like receptor 5 (TLR5) in the gut epithelium of neonate mice. Using competitive colonization experiments, we demonstrate that epithelial TLR5-mediated REG3 gamma production is critical for the counter-selection of colonizing flagellated bacteria. Comparative microbiota transfer experiments in neonate and adult wild-type and Tlr5-deficient germ-free mice reveal that neonatal TLR5 expression strongly influences the composition of the microbiota throughout life. Thus, the beneficial microbiota in the adult host is shaped during early infancy. This might explain why environmental factors that disturb the establishment of the microbiota during early life can affect immune homeostasis and health in adulthood.
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| 7. |
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| 8. |
- Hinrichsen, F., et al.
(författare)
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Microbial regulation of hexokinase 2 links mitochondrial metabolism and cell death in colitis
- 2021
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Ingår i: Cell Metabolism. - : Elsevier BV. - 1550-4131. ; 33:12
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Tidskriftsartikel (refereegranskat)abstract
- Hexokinases (HK) catalyze the first step of glycolysis limiting its pace. HK2 is highly expressed in gut epithelium, contributes to immune responses, and is upregulated during inflammation. We examined the microbial regulation of HK2 and its impact on inflammation using mice lacking HK2 in intestinal epithelial cells (Hk2(Delta IEC)). Hk2(Delta IEC) mice were less susceptible to acute colitis. Analyzing the epithelial transcriptome from Hk2(Delta IEC) mice during colitis and using HK2-deficient intestinal organoids and Caco-2 cells revealed reduced mitochondrial respiration and epithelial cell death in the absence of HK2. The microbiota strongly regulated HK2 expression and activity. The microbially derived short-chain fatty acid (SCFA) butyrate repressed HK2 expression via histone deacetylase 8 (HDAC8) and reduced mitochondrial respiration in wild-type but not in HK2-deficient Caco-2 cells. Butyrate supplementation protected wild-type but not Hk2(Delta IEC) mice from colitis. Our findings define a mechanism how butyrate promotes intestinal homeostasis and suggest targeted HK2-inhibition as therapeutic avenue for inflammation.
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