Association of liver stiffness with hepatic expression of pharmacokinetically important genes in alcoholic liver disease

Addition of statins to the standard treatment in patients with cirrhosis: Safety and efficacy

This review summarizes the safety and efficacy of statins in patients with cirrhosis. Due to concerns about the safety of statins in patients with impaired liver function, they have recently been investigated as a potential treatment option in cirrhosis. The most clinically significant adverse event is statin-related myopathy, and this may be related to the high serum statin concentrations in the setting of severely impaired liver function. Rhabdomyolysis is the most serious and potentially life-threatening manifestation. It has recently been demonstrated that the recommended dose of simvastatin in patients with decompensated cirrhosis would be 20 mg/d because higher values, such as 40 mg/d, are associated with many adverse events, especially muscle injury. Likewise, simvastatin should not be administered to patients with Model for End-stage Liver Disease score > 12 and/or Child-Pugh class C because of the high risk of severe muscle injury. Due to the pleiotropic effects, the focus on statins has shifted from being considered harmful to something useful. Through these effects, statins could prevent liver-related morbidity and mortality in cirrhotic patients. Observational studies in large populations of patients with cirrhosis have shown that treatment with statins to decrease high cholesterol levels was associated with a reduced risk of hepatic decompensation, hepatocellular carcinoma development and death. The few randomized controlled trials in patients with cirrhosis and portal hypertension showed that statins lower portal pressure, quite likely through a reduction in hepatic resistance. Another large randomized controlled trial in patients with variceal bleeding showed that simvastatin in addition to standard of care did not prevent rebleeding but improved survival rate. Despite these encouraging outcomes, the quality of the evidence regarding the use of statins is low or very low due to the observational characteristics of most of the studies involved. Therefore, it is advisable to perform further randomized controlled trials on a large series of patients with hard clinical endpoints, using different statin types and varying doses. The objectives would be to prevent liver-related morbidity and mortality rather than treating cirrhosis complications to take additional information that makes it possible to add statins to the standard of care of these patients.

Cirrhosis as new indication for statins

In the recent years, there have been an increasing number of reports on favourable effects of statins in patients with advanced chronic liver disease. These include reduction in portal pressure, improved liver sinusoidal endothelial and hepatic microvascular dysfunction, decreased fibrogenesis, protection against ischaemia/reperfusion injury, safe prolongation of ex vivo liver graft preservation, reduced sensitivity to endotoxin-mediated liver damage, protection from acute-on-chronic liver failure, prevention of liver injury following hypovolaemic shock and preventing/delaying progression of cirrhosis of any aetiology. Moreover, statins have been shown to have potential beneficial effects in the progression of other liver diseases, such as chronic sclerosing cholangitis and in preventing hepatocellular carcinoma. Because of these many theoretically favourable effects, statins have evolved from being considered a risk to kind of wonder drugs for patients with chronic liver diseases. The present article reviews the current knowledge on the potential applications of statins in chronic liver diseases, from its mechanistic background to objective evidence from clinical studies.

Development of Scaffolds with Adjusted Stiffness for Mimicking Disease-Related Alterations of Liver Rigidity

Drug-induced liver toxicity is one of the most common reasons for the failure of drugs in clinical trials and frequent withdrawal from the market. Reasons for such failures include the low predictive power of in vivo studies, that is mainly caused by metabolic differences between humans and animals, and intraspecific variances. In addition to factors such as age and genetic background, changes in drug metabolism can also be caused by disease-related changes in the liver. Such metabolic changes have also been observed in clinical settings, for example, in association with a change in liver stiffness, a major characteristic of an altered fibrotic liver. For mimicking these changes in an in vitro model, this study aimed to develop scaffolds that represent the rigidity of healthy and fibrotic liver tissue. We observed that liver cells plated on scaffolds representing the stiffness of healthy livers showed a higher metabolic activity compared to cells plated on stiffer scaffolds. Additionally, we detected a positive effect of a scaffold pre-coated with fetal calf serum (FCS)-containing media. This pre-incubation resulted in increased cell adherence during cell seeding onto the scaffolds. In summary, we developed a scaffold-based 3D model that mimics liver stiffness-dependent changes in drug metabolism that may more easily predict drug interaction in diseased livers.

Towards improved hepatocyte cultures: Progress and limitations

Hepatotoxicity is among the most frequent reasons for drug withdrawal from the market. Therefore, there is an urgent need for reliable predictive in vitro tests, which unfailingly identify hepatotoxic drug candidates, reduce drug development time, expenses and the number of test animals. Currently, human hepatocytes represent the gold standard. However, the use of hepatocytes is challenging since the cells are not constantly available and lose their metabolic activity in culture. To solve these problems many different approaches have been developed in the past decades. The aim of this review is to present these approaches and to discuss the possibilities and limitations as well as future opportunities and directions.

Isoform-Dependent Changes in Cytochrome P450-Mediated Drug Metabolism after Portal Vein Ligation in the Rat

BACKGROUND

Surgical removal of complicated liver tumors may be realized in two stages via selective portal vein ligation, inducing the atrophy of portally ligated lobes and the compensatory hypertrophy of nonligated liver lobes. Unlike morphological changes, functional aspects such as hepatic cytochrome P450 (CYP)-mediated drug metabolism remain vaguely understood, despite its critical role in both drug biotransformation and hepatic functional analysis. Our goal was the multilevel characterization of hepatic CYP-mediated drug metabolism after portal vein ligation in the rat.

METHODS

Male Wistar rats (n = 24, 210-230 g) were analyzed either untreated (controls; n = 4) or 24/48/72/168/336 h (n = 4 each) following portal vein ligation affecting approximately 80% of the liver parenchyma. Besides the weights of ligated and nonligated lobes, pentobarbital (30 mg/kg)-induced sleeping time, CYP1A(2), CYP 2B(1/2), CYP2C(6/11/13), CYP3A(1) enzyme activities, and corresponding isoform mRNA expressions, as well as CYP3A1 protein expression were determined by in vivo sleeping test, CYP isoform-selective assays, polymerase chain reaction, and immunohistochemistry, respectively.

RESULTS

Portal vein ligation triggered atrophy in ligated lobes and hypertrophy nonligated lobes. Sleeping time was transiently elevated (p = 0.0451). After an initial rise, CYP1A, CYP2B, and CYP3A enzyme activities dropped until 72 h, followed by a potent increase only in the nonligated lobes, paralleled by an early (24-48 h) transcriptional activation only in nonligated lobes. CYP2C enzyme activities and mRNA levels were bilaterally rapidly decreased, showing a late reconvergence only in nonligated lobes. CYP3A1 immunohistochemistry indicated substantial differences in positivity in the early period.

CONCLUSIONS

Beyond the atrophy-hypertrophy complex, portal vein ligation generated a transient suppression of global and regional drug metabolism, re-established by an adaptive, CYP isoform-dependent transcriptional response of the nonligated lobes.

A Standardized Collagen-Based Scaffold Improves Human Hepatocyte Shipment and Allows Metabolic Studies over 10 Days

Due to pronounced species differences, hepatotoxicity of new drugs often cannot be detected in animal studies. Alternatively, human hepatocytes could be used, but there are some limitations. The cells are not always available on demand or in sufficient amounts, so far there has been only limited success to allow the transport of freshly isolated hepatocytes without massive loss of function or their cultivation for a long time. Since it is well accepted that the cultivation of hepatocytes in 3D is related to an improved function, we here tested the Optimaix-3D Scaffold from Matricel for the transport and cultivation of hepatocytes. After characterization of the scaffold, we shipped cells on the scaffold and/or cultivated them over 10 days. With the evaluation of hepatocyte functions such as urea production, albumin synthesis, and CYP activity, we showed that the metabolic activity of the cells on the scaffold remained nearly constant over the culture time whereas a significant decrease in metabolic activity occurred in 2D cultures. In addition, we demonstrated that significantly fewer cells were lost during transport. In summary, the collagen-based scaffold allows the transport and cultivation of hepatocytes without loss of function over 10 days.

The Use of Statins in Patients With Chronic Liver Disease and Cirrhosis

PURPOSE OF REVIEW

Statins are drugs developed to treat hypercholesterolemia. Its use in patients with liver disease has been limited because one of its potential and most feared side effects is hepatotoxicity. However, there is robust evidence that supports the safety of statins in this population in the absence of severe liver dysfunction. In this review, we will summarize the efficacy and safety of statins in cirrhosis.

RECENT FINDINGS

Statins are effective in the treatment of dyslipidemia in patients with liver disease, because of their pleiotropic properties. These properties are independent of their effect on cholesterol levels, such as improving endothelial dysfunction or having antioxidant, antifibrotic, anti-inflammatory, antiproliferative, antiangiogenic, proapoptotic, or immunomodulation properties. Statins have been studied in other areas such as in treatment of portal hypertension, prevention of hepatocellular carcinoma, and/or protection against ischemia/reperfusion injury. Approved indications for statins in patients with cirrhosis are those of the general population, including dyslipidemia and increased cardiovascular risk. Compensated cirrhosis is not a contraindication. In patients with decompensated cirrhosis, statins should be prescribed with extreme caution at low doses, and with frequent monitoring of creatinine phosphokinase levels in order to detect adverse events in a timely fashion.

Addition of Simvastatin to Standard Therapy for the Prevention of Variceal Rebleeding Does Not Reduce Rebleeding but Increases Survival in Patients With Cirrhosis

BACKGROUND & AIMS

The combination of β-blockers and band ligation is the standard approach to prevent variceal rebleeding, but bleeding recurs and mortality is high. The lipid-lowering drug simvastatin decreases portal pressure, improves hepatocellular function, and might reduce liver fibrosis. We assessed whether adding simvastatin to standard therapy could reduce rebleeding and death after variceal bleeding in patients with cirrhosis.

METHODS

We performed a multicenter, double-blind, parallel trial of 158 patients with cirrhosis receiving standard prophylaxis to prevent rebleeding (a β-blocker and band ligation) in Spain from October 2010 through October 2013. Within 10 days of bleeding, subjects were randomly assigned, but stratified by Child-Pugh class of A or B vs C, to groups given simvastatin (20 mg/d the first 15 days, 40 mg/d thereafter; n = 69) or placebo (n = 78). Patients were followed for as long as 24 months. The primary end point was a composite of rebleeding and death, and main secondary end points were the individual components of the composite (death and rebleeding).

RESULTS

The primary end point was met by 30 of 78 patients in the placebo group and 22 of 69 in the simvastatin group (P = .423). Seventeen patients in the placebo group died (22%) vs 6 patients in the simvastatin group (9%) (hazard ratio for adding simvastatin to therapy = 0.39; 95% confidence interval: 0.15-0.99; P = .030). Simvastatin did not increase survival of patients with Child-Pugh class C cirrhosis. Rebleeding occurred in 28% of patients in the placebo group and 25% in the simvastatin group (P = .583). Serious adverse events occurred in 53% of patients in the placebo group and 49% in the simvastatin group (P = .752); the percentages of serious adverse events related to therapy were 11% in the placebo group vs 8% in the in the simvastatin group (P = .599). Two patients in the simvastatin group, each with advanced liver disease, developed rhabdomyolysis.

CONCLUSIONS

In a randomized controlled trial, addition of simvastatin to standard therapy did not reduce rebleeding, but was associated with a survival benefit for patients with Child-Pugh class A or B cirrhosis. Survival was not the primary end point of the study, so these results require validation. The incidence of rhabdomyolysis in patients receiving 40 mg/d simvastatin was higher than expected. European Clinical Trial Database ID: EUDRACT 2009-016500-24; ClinicalTrials.gov ID: NCT01095185.

Molecular changes in hepatic metabolism and transport in cirrhosis and their functional importance

Liver cirrhosis is the common endpoint of many hepatic diseases and represents a relevant risk for liver failure and hepatocellular carcinoma. The progress of liver fibrosis and cirrhosis is accompanied by deteriorating liver function. This review summarizes the regulatory and functional changes in phase I and phase II metabolic enzymes as well as transport proteins and provides an overview regarding lipid and glucose metabolism in cirrhotic patients. Interestingly, phase I enzymes are generally downregulated transcriptionally, while phase II enzymes are mostly preserved transcriptionally but are reduced in their function. Transport proteins are regulated in a specific way that resembles the molecular changes observed in obstructive cholestasis. Lipid and glucose metabolism are characterized by insulin resistance and catabolism, leading to the disturbance of energy expenditure and wasting. Possible non-invasive tests, especially breath tests, for components of liver metabolism are discussed. The heterogeneity and complexity of changes in hepatic metabolism complicate the assessment of liver function in individual patients. Additionally, studies in humans are rare, and species differences preclude the transferability of data from rodents to humans. In clinical practice, some established global scores or criteria form the basis for the functional evaluation of patients with liver cirrhosis, but difficult treatment decisions such as selection for transplantation or resection require further research regarding the application of existing non-invasive tests and the development of more specific tests.

Expression of P450 and nuclear receptors in normal and end-stage Chinese livers

AIM: To investigate the expression of P450 enzyme genes by using end-stage liver disease samples and trimmed normal Chinese donor livers.

METHODS: The end-stage liver disease samples [n = 93, including hepatocellular carcinoma (HCC), peri-HCC tissue, hepatitis B virus cirrhosis, alcoholic cirrhosis, and severe cirrhosis] and trimmed normal Chinese donor livers (n = 35) from The Institute of Organ Transplantation in Beijing, China. Total RNA was extracted, purified, and subjected to real-time RT-PCR analysis.

RESULTS: For cytochrome P450 enzymes 1 (CYP1) family, the expression of CYP1A2 was decreased 90% in HCC, 80% in alcoholic cirrhosis, and 65% in severe cirrhosis. For CYP2 family, the expression of CAR was decreased 50% in HCC, but increased 50% in peri-HCC tissues. Similar decreases (about 50%) of CYP2B6, CYP2C9, CYP2C19, CYP2D6 and CYP2E1 were observed in HCC, as compared to peri-HCC tissues and normal livers. CYP2C19 were decreased in all end-stage liver diseases and CYP2E1 also decreased in alcoholic cirrhosis and severe cirrhosis. For CYP3 family, the expression of PXR was decreased 60% in HCC, together with decreases in CYP3A4, CYP3A5, and CYP3A7. In contrast, the expression of CYP3A7 was slightly increased in HBV cirrhosis. The expression of CYP4A11 was decreased 85% in HCC, 7% in alcoholic cirrhosis and severe liver cirrhosis, along with decreases in PPARα. The 93 end-stage livers had much higher inter-individual variations in gene expression than 35 normal livers.

CONCLUSION: The expression of CYP enzyme genes and corresponding nuclear receptors was generally decreased in end-stage liver diseases, and significant differences in gene expression were evident between peri-HCC and HCC.

Diagnostic challenges in alcohol use disorder and alcoholic liver disease

Alcohol use disorders represent a heterogeneous spectrum of clinical manifestations that have been defined by the Diagnostic and Statistical Manual of Mental Disorders-5. Excessive alcohol intake can lead to damage of various organs, including the liver. Alcoholic liver disease includes different injuries ranging from steatosis to cirrhosis and implicates a diagnostic assessment of the liver disease and of its possible complications. There is growing interest in the possible different tools for assessing previous alcohol consumption and for establishing the severity of liver injury, especially by non-invasive methods.

In-vitro evaluation of chronic alcohol effects on expression of drug-metabolizing and drug-transporting proteins

Objectives

In alcoholics without alcoholic liver disease, boosted drug elimination has been reported. However, mechanistic explanations for this phenomenon remain uncertain. In particular, data on the potential role of drug transporters are sparse.

Methods

Using a well-established in-vitro model for induction of human drug-metabolizing and drug-transporting proteins, we evaluated the potency of ethanol and the major fermentation side-product isopentanol to alter expression and function of these proteins by quantitative real-time polymerase chain reaction, Western blotting and flow cytometry. P-glycoprotein (Pgp)-inhibiting properties of ethanol and isopentanol were investigated via calcein extrusion assay.

Key findings

Ethanol and isopentanol significantly changed expression levels of drug-metabolizing and drug-transporting proteins that normalized within 2 weeks upon withdrawal. Cytochrome P-450 2C19 and Pgp were most strongly induced. Ethanol-induced Pgp at the messenger RNA (mRNA) (twofold to eightfold) and protein level (twofold), but not at the functional level. Both compounds did not inhibit Pgp.

Conclusions

Ethanol is demonstrated to increase mRNA and protein expression of human drug transporters such as Pgp in vitro. Withdrawal of ethanol exposure causes return to non-induced conditions within weeks. Functional consequences of increased Pgp expression in alcoholics need to be evaluated by clinical trials applying selective Pgp substrates such as digoxin.