Biology subjects

Schnabl, B.

Publications and source records attributed to Schnabl, B..

5 recordsLinked to original sources

bioRxiv2026

Bacteriophage susceptibility in clinical Enterococcus faecalis reflects host genomic background and Epa-associated phage adsorption

Cytolysin-positive Enterococcus faecalis has been implicated as a disease-associated pathobiont in alcohol-associated hepatitis, motivating development of selective bacteriophage-based strategies. However, strain-level determinants of phage susceptibility remain incompletely understood. We characterized the host range of three E. faecalis phages, {Phi}Ef2.1, {Phi}Ef2.2, and {Phi}Ef2.3Ev, across 45 clinical isolates and investigated bacterial and phage factors associated with adsorption and productive infection. Isolates were characterized by whole-genome sequencing, cytolysin status, antimicrobial resistance determinants, and predicted anti-phage defense systems. Phage susceptibility was measured by efficiency of plating (EoP) and adsorption assays. Thirty-five of the 45 isolates (77.8%), including all 15 cylLs-positive isolates, were susceptible to at least one of the three phages at EoP [≥]0.01. {Phi}Ef2.1 and {Phi}Ef2.2 showed greater activity against cylLs-positive isolates, which also carried higher burdens of predicted antimicrobial resistance determinants and anti-phage defense system types. Analysis of 367 complete E. faecalis RefSeq genomes classified the variable region of the enterococcal polysaccharide antigen (epa) locus into 15 recurrent architecture groups that were associated with phage-specific adsorption patterns. Efficient adsorption did not always result in productive infection, indicating additional post-adsorption barriers. AbiD emerged as a candidate factor associated with reduced {Phi}Ef2.2 productivity, although this signal was prediction-tool dependent, while unexplained post-adsorption blocks suggest the involvement of additional uncharacterized mechanisms. These findings link naturally occurring epa architecture to phage adsorption and highlight distinct post-adsorption constraints on host range, providing a framework for rational phage selection against clinically relevant E. faecalis populations.

microbiology↗

bioRxiv2026

Targeting Microbial Bile Salt Hydrolase Reprograms Bile Acid Metabolism and Ameliorates Metabolic Dysfunction-Associated Steatohepatitis in Mice

Microbial bile salt hydrolase (BSH) plays a central role in shaping bile acid composition and gut-liver metabolic signaling, yet its therapeutic potential in metabolic dysfunction-associated steatohepatitis (MASH) remains incompletely defined. Here, we evaluated the efficacy of the non-absorbable BSH inhibitor GR-7 in a diet induced mouse model of steatohepatitis using early and late intervention strategies with different dosing regimens. GR-7 reduced food intake and exerted stage- and dose-dependent therapeutic effects, with early intervention robustly suppressing hepatic fibrosis even at low dose, whereas late-stage administration of high-dose GR-7 markedly reduced hepatic steatosis and inflammation, as evidenced by decreased liver weight, hepatic triglyceride and cholesterol levels, and plasma ALT. Although late intervention did not result in statistically significant histological reversal of fibrosis, a trend toward improvement was observed, together with suppression of fibrogenic gene expression, suggesting that prolonged treatment may further enhance antifibrotic efficacy. Mechanistically, GR-7 effectively inhibited microbial BSH activity in vivo, leading to reduced cecal unconjugated primary and secondary bile acids--including deoxycholic acid and lithocholic acid, which was associated with improved gut barrier integrity and reduced hepatic inflammation. In parallel, BSH inhibition reprogrammed hepatic bile acid metabolism toward activation of the alternative CYP27A1-mediated synthesis pathway, accompanied by reduced food intake, thereby contributing to improved hepatic lipid accumulation. Furthermore, late-stage high-dose treatment selectively remodeled the hepatic immune landscape rather than fully restoring homeostasis, highlighting immune recalibration as a key component of therapeutic response. Together, these findings identify microbial BSH inhibition as a promising microbiome-targeted therapeutic strategy for MASH. HighlightsO_LIThe non-absorbable BSH inhibitor GR-7 improves steatosis, inflammation, and fibrosis in of Western diet-induced steatohepatitis model in mice in a dose-dependent manner. C_LIO_LIGR-7 reduces food intake and body weight gain. C_LIO_LIGR-7 reduces cytotoxic secondary bile acids, including DCA and LCA. C_LIO_LIGR-7 reprograms hepatic bile acid metabolism and immune responses. C_LI

pharmacology and toxicology↗

bioRxiv2023

Fecal virome transplantation is sufficient to alter fecal microbiota and drive lean and obese body phenotypes in mice

BackgroundThe gastrointestinal microbiome plays a significant role in numerous host processes and has an especially large impact on modulating the host metabolism. Prior studies have shown that when mice receive fecal transplants from obese donors that were fed high-fat diets (HFD) (even when recipient mice are fed normal diets after transplantation), they develop obese phenotypes. These studies demonstrate the prominent role that the gut microbiota play in determining lean and obese phenotypes. While much of the credit has been given to gut bacteria, studies have not measured the impact of gut viruses on these phenotypes. To address this shortcoming, we gavaged mice with viromes isolated from donors fed HFD or normal chow. By characterizing the mices gut bacterial biota and weight-gain phenotypes over time, we demonstrate that viruses can shape the gut bacterial community and affect weight gain or loss. ResultsWe gavaged mice longitudinally over 4 weeks while measuring their body weights and collecting fecal samples for 16S rRNA amplicon sequencing. We evaluated mice that were fed normal chow or high-fat diets, and gavaged each group with either chow-derived fecal viromes, HFD-derived fecal viromes, or phosphate buffered saline controls. We found a significant effect of gavage type, where mice fed chow but gavaged with HFD-derived viromes gained significantly more weight than their counterparts receiving chow-derived viromes. The converse was also true: mice fed HFD but gavaged with chow-derived viromes gained significantly less weight than their counterparts receiving HFD-derived viromes. These results were replicated in two separate experiments and the phenotypic changes were accompanied by significant and identifiable differences in the fecal bacterial biota. Notably, there were differences in Lachnospirales and Clostridia in mice fed chow but gavaged with HFD-derived fecal viromes, and in Peptostreptococcales, Oscillospirales, and Lachnospirales in mice fed HFD but gavaged with chow-derived fecal viromes. Due to methodological limitations, we were unable to identify specific bacterial species or strains that were responsible for respective phenotypic changes. ConclusionsThis study confirms that virome-mediated perturbations can alter the fecal microbiome in an in vivo model and indicates that such perturbations are sufficient to drive lean and obese phenotypes in mice.

microbiology↗

bioRxiv2022

Systematic analysis of transcriptional and epigenetic effects of genetic variation in Kupffer cells enables discrimination of cell intrinsic and environment-dependent mechanisms

Noncoding genetic variation is a major driver of phenotypic diversity but determining the underlying mechanisms and the cell types in which it acts remain challenging problems. Here, we investigate the impact of natural genetic variation provided by phenotypically diverse inbred strains of mice on gene expression and epigenetic landscapes of Kupffer cells. Analysis of gene expression in Kupffer cells and other liver cell types derived from C57BL/6J, BALB/cJ and A/J mice provided evidence for strain-specific differences in environmental factors influencing Kupffer cell phenotypes, including preferential Leptin signaling in BALB/cJ Kupffer cells. Systematic analysis of transcriptomic and epigenetic data from F1 hybrids of these mice, and transcriptomic data from strain-specific Kupffer cells engrafted into a common host enabled quantitative assessment of cis versus trans effects of genetic variation on gene expression and an estimate of cell autonomous versus non cell autonomous effects. Under homeostatic conditions, trans effects of genetic variation were dominant, with the majority of trans regulation being non cell autonomous. In contrast, strain specific responses to acutely administered LPS were primarily associated with genetic variation acting in cis to modify response elements for lineage determining and signal dependent transcription factors. Collectively, these findings reveal cell intrinsic and environmental effects of natural genetic variation on gene expression, demonstrate the use of enhancers as detectors of trans effects of genetic variation, and provide a new resource for understanding the impact of genetic variation on gene expression in Kupffer cells.

genomics↗

bioRxiv2021

Protective and aggressive bacterial subsets and metabolites modify hepatobiliary inflammation and fibrosis in PSC.

ObjectiveConflicting microbiota data exist for primary sclerosing cholangitis (PSC) and experimental models. Goal: Define complex interactions between resident microbes and their association in PSC patients by studying antibiotic-treated specific pathogen-free (SPF) and germ-free (GF) multi-drug-resistant 2 deficient (mdr2-/-) mice. DesignWe measured weights, liver enzymes, RNA expression, histological, immunohistochemical and fibrotic biochemical parameters, fecal 16s rRNA gene profiling, and metabolomic endpoints in gnotobiotic and antibiotic-treated SPF mdr2-/- mice and targeted metagenomic analysis in PSC patients. ResultsGF mdr2-/- mice had exaggerated hepatic inflammation and fibrosis with 100% mortality by 8 weeks; early SPF autologous stool transplantation rescued liver-related mortality. Broad-spectrum antibiotics and vancomycin alone accelerated disease in weanling SPF mdr2-/- mice, indicating that vancomycin-sensitive resident microbiota protect against hepatobiliary disease. Vancomycin treatment selectively decreased Lachnospiraceae and short-chain fatty acids (SCFAs) but expanded Enterococcus and Enterobacteriaceae. Antibiotics increased cytolysin-expressing E. faecalis and E. coli liver translocation; colonization of gnotobiotic mdr2-/- mice with translocated E. faecalis and E. coli strains accelerated liver inflammation and mortality. Lachnospiraceae colonization of antibiotic pre-treated mdr2-/- mice reduced liver fibrosis, inflammation and translocation of pathobionts, while Lachnospiraceae-produced SCFA decreased fibrosis. Fecal E. faecalis/ Enterobacteriaceae was positively and Lachnospiraceae was negatively associated with PSC patients clinical severity Mayo risk scores. ConclusionsWe identified specific functionally protective and detrimental resident bacterial species in mdr2-/- mice and PSC patients with associated clinical outcomes. These insights may guide personalized targeted therapeutic interventions in PSC patients.

microbiology↗