The nuclear bile acid receptor, farnesoid X receptor (FXR), may play a pivotal role in liver fibrosis. We tested the impact of genetic FXR ablation in four different mouse models. Hepatic fibrosis was induced in wild-type and FXR knock-out mice (FXR ؊/؊ ) by CCl 4 intoxication, 3,5-diethoxycarbonyl-1,4-dihydrocollidine feeding, common bile duct ligation, or Schistosoma mansoni (S.m.)-infection. In addition, we determined nuclear receptor expression levels (FXR, pregnane X receptor (PXR), vitamin D receptor, constitutive androstane receptor (CAR), small heterodimer partner (SHP)) in mouse hepatic stellate cells (HSCs), portal myofibroblasts (MFBs), and human HSCs. Cell type-specific FXR protein expression was determined by immunohistochemistry in five mouse models and prototypic human fibrotic liver diseases. Expression of nuclear receptors was much lower in mouse and human HSCs/MFBs compared with total liver expression with the exception of vitamin D receptor. FXR protein was undetectable in mouse and human HSCs and MFBs. FXR loss had no effect in CCl 4 -intoxicated and S.m.-infected mice, but significantly decreased liver fibrosis of the biliary type (common bile duct ligation, 3,5-diethoxycarbonyl-1,4-dihydrocollidine). These data suggest that FXR loss significantly reduces fibrosis of the biliary type, but has no impact on non-cholestatic liver fibrosis. Since there is no FXR expression in HSCs and MFBs in liver fibrosis, our data indicate that these cells may not represent direct therapeutic targets for FXR ligands.

Disruption of the murine mdr2 gene leads to the complete absence of biliary phospholipids. We tested the hypothesis that the increase in biliary phospholipid output induced by fibrates is mediated via induction of the hepatic mdr2 gene and its encoded product, the P-glycoprotein canalicular flippase. Increased levels of mdr2 mRNA were observed in the liver of mice treated with different fibrates : ciprofibrate, 660p155 % (as compared with control group) ; clofibrate, 611p77 % ; bezafibrate, 410p47 % ; fenofibrate, 310p52 % ; gemfibrozil, 190p25 % (P 0n05 compared with control group). Induction of expression of the mdr gene family was specific to the mdr2 gene. Two-to three-fold increases in P-glycoprotein immunodetection were evident on the canalicular plasma-membrane domain of clofibrate-and ciprofibrate-treated mice. Biliary phospholipid output increased

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Hepatocyte gap junction proteins, connexins (Cxs) 26 and 32, are downregulated during obstructive cholestasis (OC) and lipopolysaccharide hepatocellular cholestasis (LPS-HC). We investigated rat hepatic Cxs during ethynylestradiol hepatocellular cholestasis (EE-HC) and choledochocaval fistula (CCF) and compared them with OC and LPS-HC. Levels (immunoblotting) and cellular distribution (immunofluorescence) of Cx26, -32, and -43, as well as macrophage infiltration, were studied in livers of rats under each condition. Cx26 and -32 were reduced in LPS-HC, OC, and CCF. However, in EE-HC, Cx26 did not change and Cx32 was increased. Prominent inflammation occurred in LPS-HC, OC, and CCF, which was associated with increased levels of Cx43 in LPS-HC and OC but not CCF. No inflammation nor changes in Cx43 levels occurred during EE-HC. In cultured hepatocytes, dye coupling was reduced by tumor necrosis factor-alpha and interleukins-1beta and -6, whereas reduction induced by LPS required coculture with Kupffer cells. Thus hepatocyte gap junctions are downregulated in forms of cholestasis associated with inflammation, and reduced intercellular communication might be induced in part by proinflammatory mediators.

11beta-HSD1 expression is higher in liver in comparison to adipose tissue in obese patients. The observed correlations between hepatic and VAT 11beta-HSD1 expression with dyslipidemia and insulin resistance suggest that this enzyme might have a pathogenic role in obesity and related metabolic disorders.

Background Therapeutic options to treat Non-alcoholic steatohepatitis (NASH) are limited. Mineralocorticoid receptor (MR) activation could play a role in hepatic fibrogenesis and its modulation could be beneficial for NASH. Aim To investigate whether eplerenone, a specific MR antagonist, ameliorates liver damage in experimental NASH. Methods C57bl6 mice were fed a choline-deficient-amino-acid–defined (CDAA) diet for 22 weeks with or without eplerenone supplementation. Serum levels of aminotransferases and aldosterone were measured and hepatic steatosis, inflammation, and fibrosis scored histologically. Hepatic triglyceride content (HTC) and hepatic mRNA levels of pro-inflammatory pro-fibrotic, oxidative stress-associated genes and of MR were also assessed. Results CDAA diet effectively induced fibrotic NASH, and increased the hepatic expression of pro-inflammatory, pro-fibrotic and oxidative stress-associated genes. Hepatic MR mRNA levels significantly correlated with the expression of pro-inflammatory and pro-fibrotic genes and were significantly increased in hepatic stellate cells obtained from CDAA-fed animals. Eplerenone administration was associated to a reduction in histological steatosis and attenuation of liver fibrosis development, which was associated to a significant decrease in the expression of collagen-α1, collagen type III, alpha 1 and Matrix metalloproteinase-2. Conclusion The expression of MR correlates with inflammation and fibrosis development in experimental NASH. Specific MR blockade with eplerenone has hepatic anti-steatotic and anti-fibrotic effects. These data identifies eplerenone as a potential novel therapy for NASH. Considering its safety and FDA-approved status, human studies are warranted

Therapy for nonalcoholic steatohepatitis (NASH) is limited. Andrographolide (ANDRO), a botanical compound, has a potent anti-inflammatory activity due to its ability to inhibit NF-κB. ANDRO has been also shown to inhibit the NLRP3 inflammasome, a relevant pathway in NASH. Our aim was to evaluate the effects of ANDRO in NASH and its influence on inflammasome activation in this setting. Thus, mice were fed a choline-deficient-amino-acid–defined (CDAA) diet with/without concomitant ANDRO administration (1 mg/kg, 3-times/week). Also, we assessed serum levels of alanine-aminotransferase (ALT), liver histology, hepatic triglyceride content (HTC) and hepatic expression of pro-inflammatory, pro-fibrotic and inflammasome genes. Inflammasome activation was also evaluated in fat-laden HepG2 cells. Our results showed that ANDRO administration decreased HTC and attenuated hepatic inflammation and fibrosis in CDAA-fed mice. ANDRO treatment determined a strong reduction in hepatic macrophage infiltration and reduced hepatic mRNA levels of both pro-inflammatory and pro-fibrotic genes. In addition, mice treated with ANDRO showed reduced expression of inflammasome genes. Finally, ANDRO inhibited LPS-induced interleukin-1β expression through NF-κB inhibition in fat-laden HepG2 cells and inflammasome disassembly. In conclusion, ANDRO administration reduces inflammation and fibrosis in experimental NASH. Inflammasome modulation by a NF-κB-dependent mechanism may be involved in the therapeutic effects of ANDRO.

Hepatic ischemia-reperfusion (I-R) injury frequently is associated with cholestasis. However, the underlying mechanisms are not fully understood. The aim of the study is to assess bile secretory function in vivo in rats subjected to warm lobar hepatic ischemia at different times during reperfusion. A model of lobar 70% warm hepatic ischemia for 30 minutes was used with studies conducted at 1 and 6 hours and 1, 3, and 7 days after reperfusion. Bile secretory function was assessed after selective cannulation of bile ducts of ischemic (ILs) and nonischemic lobes (NILs). Serum activity of hepatic alanine and aspartate aminotransferase was slightly increased in rats subjected to I-R, whereas serum bile salt levels increased early during reperfusion, returning to control values after 7 days. ILs showed mild reversible leukocyte infiltration and no significant necrosis. Bile flow and bile salt excretion were significantly decreased in ILs during the first 24-hour reperfusion period compared with shamoperated rats and NILs. A marked reduction in glutathione (GSH) excretion occurred at 1 and 6 hours and 1 and 3 days, which returned to control values after 7 days. Total GSH and both reduced and oxidized GSH levels in liver homogenate and arterial blood GSH levels were unchanged at all times. Protein mass of multidrug resistance protein 2 and its function, assessed by the hepatic maximum secretory rate of ceftriaxone, did not show significant changes in ILs or NILs compared with shamoperated rats. Liver tissue ␥-glutamyl transpeptidase (GGT) and ␥-glutamylcysteine synthetase activities remained unchanged, whereas biliary GGT and cysteine secretory rates were significantly increased in ILs and NILs. Administration of acivicin, a GGT inhibitor, resulted in decreased secretion of this enzyme into bile and a parallel marked increase in biliary GSH secretion compared with untreated ischemic rats. In conclusion, warm hepatic I-R induces reversible cholestatic changes in ILs. GSH secretory rates from both ILs and NILs were markedly decreased during reperfusion. The reversibility of this effect after GGT inhibition, as well as increased release of active GGT into bile and cysteine biliary secretory rates, suggest increased GSH degradation in bile. These findings might be relevant for the I-R-induced clinical cholestasis, as well as cholangiocyte injury, seen after hepatic ischemia. (Liver Transpl 2003;9:1199-1210.)