Browsing Department of microbial immunoregulation (MIKI) by Subjects
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An Integrated Metagenome Catalog Reveals New Insights into the Murine Gut Microbiome.The complexity of host-associated microbial ecosystems requires host-specific reference catalogs to survey the functions and diversity of these communities. We generate a comprehensive resource, the integrated mouse gut metagenome catalog (iMGMC), comprising 4.6 million unique genes and 660 metagenome-assembled genomes (MAGs), many (485 MAGs, 73%) of which are linked to reconstructed full-length 16S rRNA gene sequences. iMGMC enables unprecedented coverage and taxonomic resolution of the mouse gut microbiota; i.e., more than 92% of MAGs lack species-level representatives in public repositories (<95% ANI match). The integration of MAGs and 16S rRNA gene data allows more accurate prediction of functional profiles of communities than predictions based on 16S rRNA amplicons alone. Accompanying iMGMC, we provide a set of MAGs representing 1,296 gut bacteria obtained through complementary assembly strategies. We envision that integrated resources such as iMGMC, together with MAG collections, will enhance the resolution of numerous existing and future sequencing-based studies.
Microbiota Alters Urinary Bladder Weight and Gene Expression.We studied the effect of microbiota on the transcriptome and weight of the urinary bladder by comparing germ-free (GF) and specific pathogen-free (SPF) housed mice. In total, 97 genes were differently expressed (fold change > ±2; false discovery rate (FDR) p-value < 0.01) between the groups, including genes regulating circadian rhythm (Per1, Per2 and Per3), extracellular matrix (Spo1, Spon2), and neuromuscular synaptic transmission (Slc18a3, Slc5a7, Chrnb4, Chrna3, Snap25). The highest increase in expression was observed for immunoglobulin genes (Igkv1-122, Igkv4-68) of unknown function, but surprisingly the absence of microbiota did not change the expression of the genes responsible for recognizing microbes and their products. We found that urinary bladder weight was approximately 25% lighter in GF mice (p = 0.09 for males, p = 0.005 for females) and in mice treated with broad spectrum of antibiotics (p = 0.0002). In conclusion, our data indicate that microbiota is an important determinant of urinary bladder physiology controlling its gene expression and size.
Performance, Fermentation Characteristics and Composition of the Microbiome in the Digest of Piglets Kept on a Feed With Humic Acid-Rich Peat.The transition from breast milk to solid feed is a dramatic change in the nutrition of piglets, frequently necessitating antibiotic treatment. In efforts to reduce the use of antibiotics, dietetic concepts based on natural feed additives are becoming more and more important. In the present study, experiments were carried out with 15 rearing piglets (days 28–56) divided into three groups that were offered different diets (Ctr [0% peat]; H1.5 [1.5% peat]; and H3.0 [3.0% peat] based on a commercial weaner recipe; all ~178 g CP, 13.7 MJ ME, 13.3 g Lys, as-fed). The contents of cecal and colon digesta were removed at necropsy. The gas formation (4 h) in colon digesta was measured using in vitro batch fermenters. For microbiome studies, 16S rRNA amplification was performed within the hypervariable region V 4 and sequenced with Illumina MiSeq platform. DNA read mapping and statistical analysis were performed using QIIME (version 1.8.0), MicrobiomeAnalyst, RStudio, and SAS Enterprise Guide. The mean body weight of the animals at the end of the trial did not show statistical differences (in kg: Ctr: 26.1 ± 4.85, H1.5: 28.5 ± 3.41, H3.0: 26.2 ± 4.92). The daily weight gains were high for this age (in g/day; Ctr: 607 ± 157; H1.5: 692 ± 101; H3.0: 615 ± 113) and the feed to gain ratio low (in kg/kg; Ctr: 1.538; H1.5: 1.462; H3.0: 1.462). Concentrations of short-chain fatty acids in the cecal content were significantly lower when peat was used (mmol/kg wet weight; Ctr: 173 ± 30.0; H1.5:134 ± 15.0; H3.0:133 ± 17.3). Numerical differences were found in the gas formation (in mL gas per 10 mL batch in 4 h; Ctr: 7.9 ± 2.2; H1.5: 7.4 ± 2.4; H3.0: 6.6 ± 1.1). The microbiome analyses in the cecal content showed significantly higher values for alpha diversity Chao 1 index for samples from the control group. Significant differences were found for bacterial relative abundance for Tenericutes at phylum level and Mollicutes at class level (p < 0.05) in cecal microbiota. Therefore, there was initial evidence that peat influences intestinal microflora causing a shift in the overall concentration of fermentation products in both, the cecal and the colon content.
Prevotella copri in individuals at risk for rheumatoid arthritis.Rheumatoid arthritis (RA) has been associated with a relative expansion of faecal Prevotellaceae. To determine the microbiome composition and prevalence of In an ongoing cohort study of first-degree relatives (FDRs) of patients with RA, we identified 'FDR controls', asymptomatic and without autoantibodies, and individuals in pre-clinical RA stages, who had either developed anticitrullinated peptide antibodies or rheumatoid factor positivity and/or symptoms and signs associated with possible RA. Stool sampling and culture-independent microbiota analyses were performed followed by descriptive statistics and statistical analyses of community structures. A total of 133 participants were included, of which 50 were categorised as 'FDR controls' and 83 in 'pre-clinical RA stages'. The microbiota of individuals in 'pre-clinical RA stages' was significantly altered compared with FDR controls. We found a significant enrichment of the bacterial family Prevotellaceae, particularly spp. enrichment in individuals in pre-clinical stages of RA, before the onset of RA, suggests a role of intestinal dysbiosis in the development of RA.