Project description:Bile acids are multifunctional signaling molecules that play significant roles in maintaining microbial homeostasis. N6-methyladenine (m6A), the most abundant epitranscriptomic modification, mediates various biological processes by modulating RNA metabolism. However, the precise regulatory mechanisms of m6A methylation in bile acid metabolism, and its downstream effects on microbiota remain unclear. In this study, liver-specific Mettl14 knockout (Mettl14-LKO) reshaped bile acid profile and expression levels of protein related to bile acid metabolism, namely CYP7A1, FXR, and BSEP. M6A-seq data revealed m6A methylated peaks on CYP7A1. Mettl14-LKO significantly elevated expression of m6A “reader” IGF2BP3. Knockdown of IGF2BP3 inhibited CYP7A1 expression by decreasing mRNA stability. Mechanistically, Mettl14-LKO promoted bile acid synthesis by upregulating CYP7A1 expression in an m6A-IGF2BP3-dependent manner. Interestingly, Mettl14-LKO reduced bile acid content in ileum due to decreased BSEP level in liver. Noteworthy, we discovered for the first time that Mettl14 knockout in the liver altered fecal microbiota composition. Specifically, it changed the abundance of Cyanobacteria and Patescibacteria at phylum level, and Lachnochostridium, Candidatus-Saccharimonas, and Roseburia at genera level. Remarkably, Roseburia was negatively correlated with the bile acid levels and CYP7A1 expression. Our findings provide new insights into the role of METTL14 in regulating bile acid homeostasis and its impact on fecal microbiota. Roseburia emerges as a potential target for addressing metabolic diseases linked to disrupted METTL14 signaling.
Project description:Nudix hydrolase 7 (NUDT7) is a peroxisomal (acyl-)CoA-degrading enzyme that is highly expressed in the liver. We previously showed that liver-specific NUDT7 overexpression affects peroxisomal lipid metabolism, but does not prevent the increase in total liver CoA levels that occurs with fasting. Herein, we show that deletion of Nudt7 alters the composition of the hepatic acyl-CoA pool in mice fed a low fat diet, but only in males fed a western diet does the lack of NUDT7 increase total liver CoA levels. This effect is driven by the accumulation of medium-chain dicarboxylic acyl-CoAs, which are products of the oxidation of dicarboxylic fatty acids in the peroxisomes. We also show that, under conditions of increased cholesterol intake and elevated bile acid synthesis, Nudt7 deletion increases the production of tauro-muricholic acids, decreasing the hydrophobicity index of the intestinal bile acid pool and increasing fecal cholesterol excretion. Collectively, our findings reveal a key role for NUDT7 in the regulation of the final products of bile acid synthesis and dicarboxylic fatty acid oxidation
Project description:The Th2 cytokine IL-13 has been described to be involved in biliary epithelial injury and liver fibrosis in patients as well as in animal models. IL-13 was found to reduce tight junction-associated barrier function of bile ducts, to promote cholangiocyte hyperplasia, and thus causing biliary epithelial injury. We generated Abcb4-/-- and IL-13-/- double-knockout mice on fibrosis susceptible genetic background BALB/c. Molecular and cellular mechanisms of hepatic and ileal pathology were investigated by mRNA microarray. Depletion of IL-13 in Abcb4-/--mice resulted in a tenfold decrease of total serum bile acid concentrations at the age of 8 weeks and lead to a recovery of intrahepatic bile duct integrity. The decrease of serum bile acid in 8 week old mice went along with relative enhancement of bile acid excretion and normalization of the composition of fecal bile excretion, correction of fecal microbiome, and improved ileal integrity. Liver integrity, measured by serum ALT, was ameliorated in younger mice and strongly correlated with the concentration of serum bile acids. 52 weeks old Abcb4-/-IL-13-/--mice exhibited significantly reduced hepatic fibrosis.
Project description:Data acquired for conjugated bile acids with amino acids analysis of human fecal samples by targeted LC-MS. These samples are a part of a study investigating a new BSH function as an amine N-acyl transferase that conjugates amines to form bacterial bile acid amidates (BBAAs).
Project description:Background: Western diet (WD) fed Melanocortin 4 receptor-knockout (MC4R-KO) mice develop a phenotype resembling human metabolic dysfunction-associated steatohepatitis (MASH). Despite its clinical relevance, the role of the gut–liver axis in MASH pathogenesis remains unclear. This study investigated the gut-liver axis through microbiomic and metabolomic analyses of WD-fed MC4R-KO mice, and examined their association with MASH pathology. Methods: We performed an integrated microbiome and metabolome analysis of the liver, small intestinal contents, large intestinal contents, and plasma of wild-type (WT) and MC4R-KO mice fed either a normal diet or WD. Markers of hepatic inflammation, fibrosis, and steatosis measured in this study were used to assess MASH severity and to correlate microbiome and metabolite alterations. Results: WD-fed MC4R-KO mice exhibited significant hepatic steatosis, inflammation, and fibrosis. The abundance of certain microbiota, including Muribaculaceae and Allobaculum, negatively correlated with MASH severity, whereas increased levels of Desulfovibrionaceae and Bacteroides positively correlated with hepatic lipid accumulation, steatosis, and inflammation. Metabolomic profiling revealed increased triglyceride and diglyceride levels in the liver and a concomitant decrease in free fatty acids and monoglycerides in the intestines. Additionally, plasma taurine-conjugated bile acids were elevated in WD-fed MC4R-KO mice, which correlated with the reduced hepatic transport of bile salts from pathway enrichment analysis. These findings highlight substantial alterations in the gut microbiota and lipid and bile acid metabolism, indicating a mechanistic dysregulation of the gut–liver axis that may contribute to MASH progression. Conclusions: The observed gut microbial and metabolic alterations, particularly bile acid and lipid metabolism dysregulation, offer insights into potential therapeutic targets aimed at modulating the gut–liver axis to treat or prevent MASH.
Project description:Interventions: experimental group :PD-1 Knockout Engineered T Cells
Primary outcome(s): Number of participants with Adverse Events and/or Dose Limiting Toxicities as a Measure of Safety and tolerability of dose of PD-1 Knockout T cells using Common Terminology Criteria for Adverse Events (CTCAE v4.0) in patients
Study Design: historical control
Project description:Atlantic salmon can synthesize polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (20:5n-3), arachidonic acid (20:4n-6) and docosahexaenoic acid (22:6n-3) via activities of very long chain fatty acyl elongases (elovls) and fatty acyl desaturases (fads), albeit to a limited degree. Understanding molecular mechanisms of PUFA biosynthesis and regulation is a pre-requisite for sustainable use of vegetable oils in aquafeeds as current sources of fish oils are unable to meet increasing demands for omega-3 PUFAs. By generating CRISPR-mediated elovl2 knockout, we have shown that elovl2 is crucial for multi-tissue synthesis of 22:6n-3 in vivo and endogenously synthesized PUFAs are important for transcriptional regulation of lipogenic genes in Atlantic salmon. The elovl2 knockouts showed reduced levels of 22:6n-3 and accumulation of 20:5n-3 and docosapentaenoic acid (22:5n-3) in the liver, brain and white muscle, suggesting inhibition of elongation. Additionally, elovl2-knockout salmon showed accumulation of 20:4n-6 in the brain and white muscle. The impaired synthesis of 22:6n-3 induced hepatic expression of sterol regulatory element binding protein-1 (srebp-1), fatty acid synthase-b, Δ6fad-a, Δ5fad and elovl5. Our study demonstrates key roles of elovl2 at two penultimate steps of PUFA synthesis in vivo and suggests Srebp-1 as a main regulator of PUFA synthesis in Atlantic salmon.