Labetalol and soluble endoglin aggravate bile acid retention in mice with ethinylestradiol-induced cholestasis

Endoglin and soluble endoglin in liver sinusoidal endothelial dysfunction in vivo

Liver sinusoidal endothelial cells (LSECs) play a crucial role in regulating the hepatic function. Endoglin (ENG), a transmembrane glycoprotein, was shown to be related to the development of endothelial dysfunction. In this study, we hypothesized the relationship between changes in ENG expression and markers of liver sinusoidal endothelial dysfunction (LSED) during liver impairment. Male C57BL/6J mice aged 9-12 weeks were fed with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet (intrahepatic cholestasis) or choline-deficient l-amino acid defined high-fat diet (CDAA-HFD) (non-alcoholic steatohepatitis (NASH)). Significant increases in liver enzymes, fibrosis, and inflammation biomarkers were observed in both cholestasis and NASH. Decreased p-eNOS/eNOS and VE-cadherin protein expression and a significant increase in VCAM-1 and ICAM-1 expression were detected, indicating LSED in both mouse models of liver damage. A significant reduction of ENG in the DDC-fed mice, while a significant increase of ENG in the CDAA-HFD group was observed. Both DDC and CDAA-HFD-fed mice showed a significant increase in MMP-14 protein expression, which is related to significantly increased levels of soluble endoglin (sENG) in the plasma. In conclusion, we demonstrated that intrahepatic cholestasis and NASH result in an altered ENG expression, predominantly in LSECs, suggesting a critical role of ENG expression for the proper function of liver sinusoids. Both pathologies resulted in elevated sENG levels, cleaved by MMP-14 expressed predominantly from LSECs, indicating sENG as a liver injury biomarker.

Carvedilol impairs bile acid homeostasis in mice: implication for nonalcoholic steatohepatitis

Carvedilol is a widely used beta-adrenoreceptor antagonist for multiple cardiovascular indications; however, it may induce cholestasis in patients, but the mechanism for this effect is unclear. Carvedilol also prevents the development of various forms of experimental liver injury, but its effect on nonalcoholic steatohepatitis (NASH) is largely unknown. In this study, we determined the effect of carvedilol (10 mg/kg/day p.o.) on bile formation and bile acid (BA) turnover in male C57BL/6 mice consuming either a chow diet or a western-type NASH-inducing diet. BAs were profiled by liquid chromatography-mass spectrometry and BA-related enzymes, transporters, and regulators were evaluated by western blot analysis and qRT-PCR. In chow diet-fed mice, carvedilol increased plasma concentrations of BAs resulting from reduced BA uptake to hepatocytes via Ntcp transporter downregulation. Inhibition of the β-adrenoreceptor-cAMP-Epac1-Ntcp pathway by carvedilol may be the post-transcriptional mechanism underlying this effect. In contrast, carvedilol did not worsen the deterioration of BA homeostasis accompanying NASH; however, it shifted the spectra of BAs toward more hydrophilic and less toxic α-muricholic and hyocholic acids. This positive effect of carvedilol was associated with a significant attenuation of liver steatosis, inflammation, and fibrosis in NASH mice. In conclusion, our results indicate that carvedilol may increase BAs in plasma by modifying their liver transport. In addition, carvedilol provided significant hepatoprotection in a NASH murine model without worsening BA accumulation. These data suggest beneficial effects of carvedilol in patients at high risk for developing NASH.