Project description:Background & Aims: Non-alcoholic fatty liver disease (NALFLD)-associated changes in gut microbiota are important drivers of disease progression toward fibrosis. Therefore, reversing microbiota alterations could ameliorate NAFLD progression. Oat beta-glucan, a non-digestible polysaccharides, has shown promising therapeutic effects on hyperlipidemia associated with NAFLD, but its impact on gut microbiota and most importantly NAFLD fibrosis remains unknown. Methods: We performed detailed metabolic phenotyping including body composition, glucose tolerance, and lipid metabolism as well as comprehensive characterization of the gut-liver axis in a western-style diet (WSD)-induced model of NAFLD and assessed the effect of a beta-glucan intervention on early and advanced liver disease. Gut microbiota was modulated using broad-spectrum antibiotic (Abx) treatment. Results: Oat beta-glucan supplementation did not affect WSD-induced body weight gain, glucose intolerance, and the metabolic phenotype remained largely unaffected. Interestingly, oat beta-glucan dampened NAFLD inflammation, associated with significantly reduced monocyte-derived macrophages (MoMFs) infiltration, fibroinflammatory gene expression, and strongly reduced fibrosis development. Mechanistically, this protective effect was not mediated by changes in bile acid composition or signaling, but was dependent on gut microbiota and was lost upon Abx treatment. Specifically, oat beta-glucan partially reversed unfavorable changes in gut microbiota, resulting in an expansion of protective taxa, including Ruminococcus, and Lactobacillus followed by reduced translocation of TLR ligands. Conclusions: Our findings identify oat beta-glucan as a highly efficacious food supplement that dampens inflammation and fibrosis development in diet-induced NAFLD. These results, along with its favorable dietary profile, suggest that it may be a cost-effective and well-tolerated approach to preventing NAFLD progression and should be assessed in clinical studies.
Project description:Gut microbiota has profound effects on obesity and associated metabolic disorders. Targeting and shaping the gut microbiota via dietary intervention using probiotics, prebiotics and synbiotics can be effective in obesity management. Despite the well-known association between gut microbiota and obesity, the microbial alternations by synbiotics intervention, especially at the functional level, are still not characterized. In this study, we investigated the effects of synbiotics on high fat diet (HFD)-induced metabolic disorders, and systematically profiled the microbial profile at both the phylogenetic and functional levels. Synbiotics significantly reversed the HFD-induced change of microbial populations at the levels of richness, taxa and OTUs. Potentially important species Faecalibaculum rodentium and Alistipes putredinis that might mediate the beneficial effects of synbiotics were identified. At the functional level, short chain fatty acid and bile acid profiles revealed that interventions significantly restored cecal levels of acetate, propionate, and butyrate, and synbiotics reduced the elevated total bile acid level. Metaproteomics revealed the effect of synbiotics might be mediated through pathways involved in carbohydrate, amino acid, and energy metabolisms, replication and repair, etc. These results suggested that dietary intervention using our novel synbiotics alleviated HFD-induced weight gain and restored microbial ecosystem homeostasis phylogenetically and functionally.
Project description:To evaluate the DC genome-wide gene expression in response to beta-glucan and its regulation by IL-1 receptor antagonist (IL-1RA) we used a whole genome microarray. The gene expression profiling was performed in DC left untreated or exposed to beta-glucan for 4 and 12 h, in absence or presence of IL-1RA. This strategy allowed the identification of early/immediate and late/secondary genes regulated by beta-glucan in an IL-1-dependent and -independent manner. Human monocyte-derived DC were obtained by a 6/7-d cultures of freshly isolated monocytes with recombinant human IL-4 (10 ng/ml) and GM-CSF (50 ng/ml). Beta-glucan-associated gene expression and its regulation by IL-1RA in human DC was measured in cells left untreated or at 4 and 12 h after exposure to 10 ug/ml of particulate beta-glucan in absence or presence of 2.5 ug/ml of IL-1RA. Five different conditions (Untreated 0h, beta-glucan 4h, IL-1RA + beta-glucan 4h, beta-glucan 12h, and IL-1RA + beta-glucan 12h) were tested using DC from three different donors.
Project description:A clone encoding carboxymethylcellulase activity was isolated during functional screening of a human gut metagenomic library using Lactococcus lactis MG1363 as heterologous host. The insert sequence revealed a glycoside hydrolase family 9 (GH9) catalytic domain with sequence similarity to a gene from Coprococcus sp. ART55/1, which is closely related to Coprocococcus eutactus. Surveys of available genomes indicated a limited distribution of GH9 domains among dominant human colonic anaerobes. Genomes of two Coprococcus-related strains showed the presence of two GH9-encoding and four GH5-encoding genes, however, the strains did not appear to be able to degrade cellulose. Instead, they grew well on beta-glucans and one of the strains also showed growth on galactomannan, galactan and glucomannan. Gene expression and proteomic analysis of Coprococcus sp. ART55/1 grown on cellobiose, beta-glucan and lichenan led to a similar change in expression in comparison to glucose. On beta-glucan and lichenan only, one of the four GH5 genes was strongly upregulated. Growth on glucomannan lead to a transcriptional response of many genes, in particular a strong upregulation of glycoside hydrolases involved in mannan degradation. Thus, beta-glucans are a major growth substrate for species related to Coprococcus eutactus, with glucomannan and galactans alternative substrates for some strains.
Project description:C-type lectin receptors (CLRs) are a large family of immunoreceptors that recognizes polysaccharides exposed on pathogens and triggers innate immune responses. However, the ligand spectrums of the whole members have not been fully understood. In this study, we found that seaweed-derived fucan activates cells expressing human Dectin-1 but not mouse Dectin-1. In fucan, low-valency β-glucan appeared to represent this activity, as the ligand activity was eliminated by the treatment of westase, a β-glucanase. Another low-valency β-glucan, laminarin, also acts as an agonist on human Dectin-1 but not for mouse Dectin-1, whereas high-valency β-glucan curdlan activated both human and mouse Dectin-1. Reciprocal mutagenesis analysis revealed that the ligand-binding domain of human Dectin-1 did not determine its unique sensitivity to low-valency β-glucan. Rather, its intracellular domain contributes to render human Dectin-1 reactive to low-valency β-glucan. Within the hDectin-1 intracellular domain, only two amino acids, Glu2 and Pro5, were sufficient to confer sensitivity on mouse Dectin-1. Conversely, the introduction of mouse-type amino acids, Lys2 and Ser5, to human Dectin-1 reduced the reactivity. These results suggest that the intracellular domain, but not the ligand binding domain, of Dectin-1 modulate their functions which determine the ligand spectrum.
Project description:Analysis of breast cancer survivors' gut microbiota after lifestyle intervention, during the COVID-19 lockdown, by 16S sequencing of fecal samples.