Lars P. Bechmann

The interaction of hepatic lipid and glucose metabolism in liver diseases

It is widely known that the liver is a central organ in lipogenesis, gluconeogenesis and cholesterol metabolism. However, over the last decades, a variety of pathological conditions highlighted the importance of metabolic functions within the diseased liver. As observed in Western societies, an increase in the prevalence of obesity and the metabolic syndrome promotes pathophysiological changes that cause non-alcoholic fatty liver disease (NAFLD). NAFLD increases the susceptibility of the liver to acute liver injury and may lead to cirrhosis and hepatocellular cancer. Alterations in insulin response, β-oxidation, lipid storage and transport, autophagy and an imbalance in chemokines and nuclear receptor signaling are held accountable for these changes. Furthermore, recent studies revealed a role for lipid accumulation in inflammation and ER stress in the clinical context of liver regeneration and hepatic carcinogenesis. This review focuses on novel findings related to nuclear receptor signaling - including the vitamin D receptor and the liver receptor homolog 1 - in hepatic lipid and glucose uptake, storage and metabolism in the clinical context of NAFLD, liver regeneration, and cancer.

Free fatty acids repress small heterodimer partner (SHP) activation and adiponectin counteracts bile acid‐induced liver injury in superobese patients with nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in industrialized countries and may proceed to steatohepatitis (NASH). Apoptosis and free fatty acid (FFA)‐induced lipotoxicity are important features of NASH pathogenesis. We have shown a hepatoprotective effect of adiponectin in steatotic livers of hepatitis C virus (HCV) patients and recent data links bile acid (BA) metabolism to the pathogenesis of NAFLD. The aim of this study was to identify potential interactions between BA and FFA metabolism in NAFLD. Liver biopsies and serum samples from 113 morbidly obese patients receiving bariatric surgery, healthy individuals, and moderately obese NAFLD patients were studied. Serum FFA, BA, and M30 were increased in NASH versus simple steatosis, while adiponectin was significantly decreased. The NAFLD activity score (NAS) score correlated with BA levels and reversely with adiponectin. Adiponectin reversely correlated with CD95/Fas messenger RNA (mRNA) and hepatocellular apoptosis. The BA transporter high‐affinity Na+/taurocholate cotransporter (NTCP) and the BA synthesizing enzyme cholesterol 7 alpha‐hydroxylase (CYP7A1) were significantly up‐regulated in obese patients and hepatoma cells exposed to FFA. Up‐regulation of NTCP and CYP7A1 indicate failure to activate small heterodimer partner (SHP) upon farnesoid X receptor (FXR) stimulation by increasing BA concentrations. In line with the NAS score, adiponectin levels were reversely correlated with BA levels. Adiponectin correlated with NTCP and affects Cyp7A1 expression both in vivo and in vitro. Conclusion: BA synthesis and serum BA levels correlated with disease severity in NAFLD, while adiponectin is reversely correlated. FFA exposure prevented SHP‐mediated repression of NTCP and Cyp7A1 expression, which lead to increased BA synthesis and uptake. In NASH, BA accumulation induced hepatocyte cell death and late FXR activation failed to prevent hepatocyte injury due to decreased adiponectin levels. Early treatment with FXR ligands and/or adiponectin‐receptor agonists might prevent NASH. (HEPATOLOGY 2013;57:1394–1406)

Acute liver failure is associated with elevated liver stiffness and hepatic stellate cell activation

Acute liver failure (ALF) is associated with massive short‐term cell death, whereas chronic liver injury is accompanied by continuous cell death. Hepatic stellate cells (HSCs) contribute to tissue repair and liver fibrosis in chronic liver injury, although their role in ALF remains unexplained. Twenty‐nine patients (median age = 43 years, 17 females and 12 males) with ALF according to the Acute Liver Failure Study Group criteria were included. Upon the diagnosis of ALF and after 7 days, we determined liver stiffness (LS) with FibroScan, standard laboratory parameters, and serum levels of matrix metalloproteinase 1 (MMP‐1), MMP‐2, MMP‐9, tissue inhibitor of metalloproteinases 1 (TIMP‐1), TIMP‐2, hyaluronic acid, and markers of overall cell death (M65) and apoptosis (M30). Stellate cell activation and progenitor response were analyzed immunohistochemically in biopsy samples of 12 patients with α‐smooth muscle actin (α‐SMA), keratin‐17, and keratin‐19 staining, respectively. Cell death markers (M30 level = 2243 ± 559.6 U/L, M65 level = 3732 ± 839.9 U/L) and fibrosis markers (TIMP‐1 level = 629.9 ± 69.4 U/mL, MMP‐2 level = 264 ± 32.5 U/mL, hyaluronic acid level = 438.5 ± 69.3 μg/mL) were significantly increased in patients versus healthy controls. This was paralleled by collagen deposition, elevated α‐SMA expression, and higher LS (25.6 ± 3.0 kPa). ALF was associated with ductular progenitor proliferation. Conclusion: Our results demonstrate HSC activation and a progenitor response in ALF. Positive correlations between LS, the degree of liver cell damage, and the intensity of HSC activation suggest that fibrosis is a response to ALF in an attempt to repair damaged tissue. (Hepatology 2010)

Low‐molecular‐weight heparin in patients with advanced cirrhosis

Background & aims: The use of low‐molecular‐weight heparins (LMWH) in patients with advanced liver diseases is frequently avoided because of the enhanced risk of bleeding complications. However, many patients with impaired liver function are at a high risk of thrombosis or have an indication for therapeutic anticoagulation. Therefore, the aim of this study was to evaluate the pharmacokinetics of LMWH in patients with cirrhosis.

Apoptosis is associated with CD36/fatty acid translocase upregulation in non-alcoholic steatohepatitis

Background & aims: Hepatocyte apoptosis is a key event in non‐alcoholic steatohepatitis (NASH). We studied the effect of obesity on free fatty acid (FFA) levels, fatty acid transport proteins (FATPs) and on extrinsic and intrinsic activation of apoptosis in the liver.

Vitamin D counteracts fibrogenic TGF-β signalling in human hepatic stellate cells both receptor-dependently and independently

Objective Non-alcoholic fatty liver disease (NAFLD) is closely linked to obesity and constitutes part of the metabolic syndrome, which have been associated with low serum vitamin D (VD). Due to known crosstalk between VD and transforming growth factor (TGF)-β signalling, VD has been proposed as an antifibrotic treatment. Design We evaluated the association between VD, the vitamin D receptor (VDR) and liver fibrosis in primary human hepatic stellate cells (phHSC) and 106 morbidly obese patients with NAFLD. Results Treating phHSC with VD ameliorated TGF-β-induced fibrogenesis via both VDR-dependent and VDR-independent mechanisms. Reduction of fibrogenic response was abolished in cells homozygous for GG at the A1012G single nucleotide polymorphisms within the VDR gene. Compared with healthy livers, NAFLD livers expressed higher levels of VDR mRNA and VDR fragments. VDR mRNA was lower in patients homozygous for GG at A1012G and expression of pro-fibrogenic genes was higher in patients carrying the G allele. Conclusions VD may be an antifibrotic treatment option early in the onset of fibrosis in specific genotypes for VDR. Known polymorphisms of the VDR may influence the response to VD treatment.

Adiponectin inhibits steatotic CD95/Fas up-regulation by hepatocytes: therapeutic implications for hepatitis C.

BACKGROUND/AIMS Steatosis may trigger hepatocytes to up-regulate CD95/Fas thereby increasing susceptibility to apoptosis, inflammation and fibrosis. We investigated this concept and potential roles of adiponectin and its receptors (AdipoR1; AdipoR2) in chronically HCV-infected patients. METHODS In 98 HCV+ patients and 20 controls, sera were tested for HCV genotypes, FFAs, adiponectin and the M30 apoptosis indicator, and biopsies were evaluated for steatosis/inflammation/fibrosis, CD95/Fas (mRNA/protein), adiponectin (mRNA/protein), AdipoR1/-R2 (mRNA) and M30 (protein). We also questioned whether adiponectin protects HepG2 hepatoblastoma cells from FFA-triggered CD95/Fas up-regulation and apoptosis. RESULTS Patients [HCV clades 1 (78%), 2 (3%) and 3 (19%)] revealed increased FFA and adiponectin serum levels (p = .005). Hepatocyte CD95/Fas up-regulation correlated with steatosis, inflammation and fibrosis (p = .004). Advanced fibrosis correlated significantly (p = .05) with serum M30. Liver adiponectin correlated with steatosis (p = .016), CD95/Fas (p < .001) and inflammation/fibrosis. Hepatocyte AdipoR2 mRNA specifically correlated with serum adiponectin and steatosis (p = .003), while hepatocyte AdipoR1 mRNA dropped in pronounced fibrosis (p = .060). Finally, adiponectin protected HepG2 cells from FFA-triggered CD95/Fas expression and induction of apoptosis (p = .0396). CONCLUSIONS In chronic HCV infection, steatosis up-regulates hepatocyte CD95/Fas and thus increases apoptosis, which facilitates inflammation and fibrosis. The physiologic countermeasure of adiponectin up-regulation may offer clues for future therapeutic intervention.

Acute Liver Failure in a Metropolitan Area in Germany: a Retrospective Study (2002 – 2008)

OBJECTIVES To determine current etiologies of acute liver failure (ALF) and clinical and laboratory parameters associated with the outcome upon ALF, so as to identify the frequency of present causes of ALF in Germany as well as potential new prognostic parameters. PATIENTS 134 adult patients (63 % females / 37 % males) aged 41 +/- 16 years (median: 38 years) with established ALF criteria. DESIGN AND SETTING A retrospective study (1 / 2002 - 4 / 2008) on ALF patients from the Ruhr Area, the largest urban region located in northwestern Germany. Clinical and laboratory data were collected for a period of four weeks after study admission. RESULTS Etiologies of ALF were identified as drug toxicity (39.6 % of the cases); combined viral hepatitides (23.1 %); or miscellaneous (16.4 %). In 20.9 % of the cases, the etiology remained indeterminate. Overall patient survival at four weeks was 81.3 %. While 89 patients (66.4 %) recovered under best supportive therapy, 26 patients (19.4 %) had to undergo liver transplantation. Increased body mass indices were significantly (p < 0.003) associated with a poor outcome. Intriguingly, high levels of cholestatic enzymes significantly (p < 0.01) correlated with a positive outcome. CONCLUSIONS In providing first data on current ALF etiologies Germany, this study reveals that drug toxicity - in particular due to acetaminophen - has replaced viral hepatitis as the most single frequent cause of ALF in a densely populated urban area; this correlates with similar findings in the USA, the UK and Scandinavia. Lower body mass indices and elevated cholestatic enzyme levels had statistically significant prognostic power.

Adipocyte cell size, free fatty acids and apolipoproteins are associated with non-alcoholic liver injury progression in severely obese patients

PURPOSE Obesity is a modern pandemic with continuous expansion and represents an independent risk factor for non-alcoholic fatty liver disease (NAFLD), the most common liver disease in westernized countries. The crosstalk between adipose tissue and the liver is key to the development of NAFLD. PROCEDURES Therefore, in an observational study blood, visceral adipose tissue and liver tissue were obtained from 93 severely obese patients with a mean age of 43 years and mean BMI of 52 kg/m2 at the time of weight loss surgery. In a subset of patients a follow-up blood sample was obtained 6 weeks after surgery to assess acute effects of weight loss. In addition to routine parameters of liver injury, serum samples were analyzed for leptin, adiponectin, free fatty acids (FFAs), and several apolipoproteins. MAIN FINDINGS The diameter of visceral adipocytes correlated to liver injury, serum markers of inflammation and serum adipokine levels. Liver injury assessed by serology (ALT, AST) and histology (NAFLD activity score, NAS) was independent of the BMI. However, serum levels of triglycerides and Apolipoprotein CIII (ApoCIII) were associated with NAS. Serum levels and composition of FFAs, especially long chain FFAs, also correlated with NAS. Analysis of serum samples six weeks after surgery revealed beneficial changes in serum triglycerides, levels of ApoCIII and several FFAs. CONCLUSIONS In severely obese patients beneficial effects on liver injury can been observed as early as six weeks after bariatric surgery. These effects may be explained by the observed changes in adipose tissue and lipid metabolism. Collectively, these findings underline the importance of the link between adipose tissue and the liver.

Acute Management of Refractory Variceal Bleeding in Liver Cirrhosis by Self-Expanding Metal Stents

Background and Aims: Current treatment strategies of variceal bleeding (VB) include banding and sclerotherapy. However, up to 10% of bleeding events remain refractory to standard therapy with high mortality. With this study, we aimed to evaluate the implantation of self-expanding metal stents (SEMS) for the management of therapy-refractory variceal bleeding. Patients and Methods: Eight cirrhotic patients who presented to our unit with a total of 9 refractory bleeding events were treated by SEMS placement. Results: Stenting resulted in immediate hemostasis in all cases without recurrent bleeding with SEMS in situ. After stabilization, 1 patient was treated by transjugular intrahepatic portosystemic shunt (TIPS) and after the second bleeding episode by TIPS dilation. One patient underwent orthotopic liver transplantation (OLT). The remaining patients were treated with standard drug regimens to reduce portal pressure. The SEMS were removed after a median of 11 days. No acute hemorrhage was noted on stent retrieval. While no early rebleeding occurred in the patients after TIPS implant, TIPS dilation or OLT, 3 out of 5 patients on conservative treatment experienced recurrence of VB within 9 days after SEMS removal. Conclusions: SEMS placement sufficiently stops hemorrhage in refractory VB. Due to the high rebleeding rate after conservative treatment alone following SEMS removal, this procedure may be utilized as a mere bridging method. Additional interventional and/or surgical methods to effectively reduce portal pressure (i.e. TIPS, OLT) should be considered. Further studies to evaluate the optimum treatment algorithm of refractory esophageal VB are warranted.