Deficiency Of Intestinal Epithelial Piezo1 Protects Mice From Hepatic Steatosis Induced By High-Fat Diet

Aim:Non-alcoholic fatty liver disease(NAFLD)is the primary cause of chronic liver disease,but there is a lack of effective therapies except lifestyle modification.Abnormal gut-liver interaction is a crucial pathophysiological mechanism of NAFLD,and the concept of’Leveraging the gut to treat liver disease’ represented by modulating intestinal farnesoid X receptor(FXR)signaling and bile acid(BA)metabolism has become a research hotspot.Mechanosensitive cation channel Piezo1 plays an important role in maintaining gut-liver axis homeostasis and nutritional metabolism balance.However,questions remain about whether intestinal epithelial Piezol can affect liver metabolism and the role of Piezol in NAFLD and its related metabolic disturbances.Methods:1.Intestine epithelial cell(IEC)specific Piezol-null(PiezolΔIEC)mice was generated.The effects of physiological intestinal epithelial Piezol deficiency on intestinal structure and epithelial function were explored.Intestinal histology was evaluated by H&E staining,and intestinal epithelial gene expression profile was detected by RNA-seq analysis.2.The effect of physiological intestinal epithelial Piezol deficiency on hepatic lipid metabolism was explored.Hepatic fat fraction was measured by MRI scanning,hepatic lipid deposition was evaluated by H&E and ORO staining,hepatic function and serum lipids were detected by commercial biochemical kits,and mRNA expression of genes involved in hepatic lipid metabolism was assessed by RT-qPCR.3.NAFLD model was constructed by feeding the mice with high-fat diet(HFD)(60%kcal from fat)for 12 weeks.The effects of intestinal epithelial Piezol deficiency on HFD-induced hepatic steatosis and systemic energy metabolism alterations were explored.4.The mechanism underlying improved hepatic steatosis mediated by intestinal epithelial Piezol deficiency was explored.4.1.Alteration of intestinal epithelial gene expression profile in Piezo1ΔIEC HFD mice was detected by RNA-seq analysis.4.2.Alteration of intestinal lipid absorption and barrier function in Piezo1ΔIEC HFD mice was explored.4.3.Alterations of intestinal FXR signaling,hepatic FXR signaling and hepatic bile acid synthesis in Piezo1ΔIEC HFD mice were detected.Ileum expression of FXR and target genes was detected by RNA-seq,RT-qPCR and ELISA.Hepatic expression of FXR and target genes,and genes involved in bile acid synthesis was detected by RT-qPCR.4.4.The modulation effect of Piezol on intestinal FXR signaling was validated by cell experiment.The expression of FXR and target genes in human colon cancer cell line HT-29 cell intervened by Piezol agonism or knockout was detected by Western blot.4.5.The mechanism underlying the modulation effect of Piezol on FXR signaling was explored.Alterations of gut microbiota and bile acids profile in cecum content of Piezo1ΔIEC HFD mice were detected by 16S rRNA sequencing and BA targeted metabolomics,respectively.Results:1.Physiological deficiency of intestinal epithelial Piezol caused no apparent alteration of intestinal morphology,with a weak influence on intestinal epithelial gene expression profile.2.Physiological deficiency of intestinal epithelial Piezol had a potential protective effect on hepatic lipid metabolism.The hepatic fat fraction,serum lipids and mRNA expression of several genes involved in hepatic lipid metabolism were decreased in Piezo1ΔIEC mice.3.Deficiency of intestinal epithelial Piezol protected mice from HFD-induced hepatic steatosis,with a modest effect on systemic energy metabolism.Under HFD challenge,Piezo1ΔIEC mice displayed reduced hepatic fat fraction as well as hepatic steatosis,improved hepatic function and serum lipids,and downregulated mRNA expression of genes involved in hepatic lipid transport and synthesis.Piezo1ΔIEC HFD mice tended to have lower body weight,fat mass and white adipose tissue weight,which were lack of statistical significance,without notable changes in metabolic rates,food intake,blood glucose or insulin sensitivity.4.Deficiency of intestinal epithelial Piezol attenuated hepatic steatosis through inhibition of intestinal FXR signaling.Piezo1ΔIEC HFD mice showed a distinctive intestinal epithelial gene expression profile.Piezo1ΔIEC HFD mice displayed no significant alteration of lipid absorption or barrier function.Intestinal epithelial Piezol deficiency inhibited HFD-activated ileum FXR signaling,and upregulated hepatic bile acid synthesis,therefore improving hepatic steatosis.The modulation effect of Piezol on intestinal FXR signaling was validated by HT-29 cell interventions.Piezol modulated FXR signaling in a microbiota or BA independent manner.Conclusion:Deficiency of intestinal epithelial Piezol protected mice from HFD-induced hepatic steatosis through inhibition of FXR signaling,accompanying with a modest effect on systemic energy metabolism.Thus,intestinal Piezol-FXR axis could be a potential drug target for NAFLD therapy.