The challenge of developing novel pharmacological therapies for non-alcoholic steatohepatitis

Current Advances in the Regulatory Effects of Bioactive Compounds from Dietary Resources on Nonalcoholic Fatty Liver Disease: Role of Autophagy

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease characterized by lipid metabolic disorder primarily due to sedentary lifestyles and excessive food consumption. However, there are currently no approved and effective drugs available to treat NAFLD. In recent years, research has shown that dietary bioactive compounds, such as polysaccharides, polyphenols, flavones, and alkaloids, have the potential to improve NAFLD by regulating autophagy. However, there is no up-to-date review of research progress in this field. This review aims to systematically summarize and discuss the regulatory effects and molecular mechanisms of dietary bioactive compounds on NAFLD through the modulation of autophagy. The existing research has demonstrated that some dietary bioactive compounds can effectively improve various aspects of NAFLD progression, such as lipid metabolism, insulin resistance (IR), endoplasmic reticulum (ER) stress, oxidative stress, mitochondrial homeostasis, and inflammation. Molecular mechanism studies have revealed that they exert their beneficial effects on NAFLD through autophagy-mediated signaling pathways, predominantly involving transcription factor EB (TFEB), mammalian target of rapamycin (mTOR), adenosine monophosphate-activated protein kinase (AMPK), peroxisome proliferator-activated receptors (PPARs), SIRT, and PTEN-induced kinase 1 (PINK1)/parkin. Furthermore, the challenges and prospects of current research in this field are highlighted. Overall, this review provides valuable insights into the potential treatment of NAFLD using dietary bioactive compounds that can modulate autophagy.

Ferulic Acid and P-Coumaric Acid Synergistically Attenuate Non-Alcoholic Fatty Liver Disease through HDAC1/PPARG-Mediated Free Fatty Acid Uptake

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease and has become a growing public health concern worldwide. Polyphenols may improve high-fat diet (HFD)-related NAFLD. Our previous study found that ferulic acid (FA) and p-coumaric acid (p-CA) were the polyphenols with the highest content in foxtail millet. In this study, we investigated the mechanism underlying the impact of ferulic acid and p-coumaric acid (FA/p-CA) on non-alcoholic fatty liver (NAFLD). The association of FA and p-CA with fatty liver was first analyzed by network pharmacology. Synergistic ameliorating of NAFLD by FA and p-CA was verified in oleic acid (OA) and palmitic acid (PA) (FFA)-treated hepatocytes. Meanwhile, FA/p-CA suppressed final body weight and TG content and improved liver dysfunction in HFD-induced NAFLD mice. Mechanistically, our data indicated that FA and p-CA bind to histone deacetylase 1 (HDAC1) to inhibit its expression. The results showed that peroxisome proliferator activated receptor gamma (PPARG), which is positively related to HDAC1, was inhibited by FA/p-CA, and further suppressed fatty acid binding protein (FABP) and fatty acid translocase (CD36). It suggests that FA/p-CA ameliorate NAFLD by inhibiting free fatty acid uptake via the HDAC1/PPARG axis, which may provide potential dietary supplements and drugs for prevention of NAFLD.

Therapeutic Effects of Resveratrol on Nonalcoholic Fatty Liver Disease Through Inflammatory, Oxidative Stress, Metabolic, and Epigenetic Modifications

The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing around the world, in association with the progressive elevation in overweight and obesity. The accumulation of lipids in NAFLD patients contributes to the development of insulin resistance, inflammation and oxidative stress in hepatocytes, and alteration of blood lipids and glycaemia. There are currently no effective pharmacological therapies for NAFLD, although lifestyle and dietary modifications targeting weight reduction are among the prevailing alternative approaches. For this reason, new approaches should be investigated. The natural polyphenol resveratrol represents a potential new treatment for management of NAFLD due to anti-inflammatory and antioxidant properties. Although preclinical trials have demonstrated promising results of resveratrol against NALFD, the lack of conclusive results creates the need for more trials with larger numbers of patients, longer time courses, and standardized protocols.

Ferulic acid ameliorates intrahepatic triglyceride accumulation in vitro but not in high fat diet-fed C57BL/6 mice

Phenolic acids can improve obesity-related and metabolic syndrome-related conditions including non-alcoholic fatty liver disease (NAFLD). In this study, the effects of ferulic acid (FA) on the metabolic changes related to NAFLD were investigated in oleic acid (OA)-treated HepG2 cells and C57BL/6 mice fed a high fat diet (HFD). In vitro, FA (25 and 50 μg/mL) treatment significantly reduced cellular lipid accumulation with no obvious cytotoxicity, in-part mediated by the suppression of ERK1/2, JNK1/2/3, and HGMB1 expression. However, in vivo administration of FA (20 mg/kg bw·day) for 17 weeks led to no obvious effects on body weight and liver weight gain, blood lipid profiles, or histological abnormalities in obese C57BL/6 mice induced by HFD. Taken together, the positive effects of FA on the reduction of hepatic triglyceride accumulation were therefore demonstrated in cellular model, while its hepatic protective effects might need to be further explored in rodent models and clinical trials.

Non-alcoholic fatty liver disease to metabolic dysfunction-associated fatty liver disease: Conceptual changes for clinicians, researchers and patients

Non-alcoholic fatty liver disease (NAFLD) is now the most common etiology of chronic liver disease threatening global public health. However, the name "NAFLD" is no longer appropriate with the change of time. Recently, a new term, "metabolic dysfunction-associated fatty liver disease" has been proposed by an international panel of experts, which implies profound conceptual changes in terms of its metabolism-related etiology and disease heterogeneity. In this article we discuss the specific conceptual changes that clinicians, researchers and patients must absorb.

COVID-19 and comorbidities: A role for dipeptidyl peptidase 4 (DPP4) in disease severity?

The coronavirus disease 2019 (COVID-19) pandemic is caused by a novel betacoronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), similar to SARS-CoV and Middle East respiratory syndrome (MERS-CoV), which cause acute respiratory distress syndrome and case fatalities. COVID-19 disease severity is worse in older obese patients with comorbidities such as diabetes, hypertension, cardiovascular disease, and chronic lung disease. Cell binding and entry of betacoronaviruses is via their surface spike glycoprotein; SARS-CoV binds to the metalloprotease angiotensin-converting enzyme 2 (ACE2), MERS-CoV utilizes dipeptidyl peptidase 4 (DPP4), and recent modeling of the structure of SARS-CoV-2 spike glycoprotein predicts that it can interact with human DPP4 in addition to ACE2. DPP4 is a ubiquitous membrane-bound aminopeptidase that circulates in plasma; it is multifunctional with roles in nutrition, metabolism, and immune and endocrine systems. DPP4 activity differentially regulates glucose homeostasis and inflammation via its enzymatic activity and nonenzymatic immunomodulatory effects. The importance of DPP4 for the medical community has been highlighted by the approval of DPP4 inhibitors, or gliptins, for the treatment of type 2 diabetes mellitus. This review discusses the dysregulation of DPP4 in COVID-19 comorbid conditions; DPP4 activity is higher in older individuals and increased plasma DPP4 is a predictor of the onset of metabolic syndrome. DPP4 upregulation may be a determinant of COVID-19 disease severity, which creates interest regarding the use of gliptins in management of COVID-19. Also, knowledge of the chemistry and biology of DPP4 could be utilized to develop novel therapies to block viral entry of some betacoronaviruses, potentially including SARS-CoV-2.

Dietary Polyphenols and Mitochondrial Function: Role in Health and Disease

Mitochondria are cytoplasmic double-membraned organelles that are involved in a myriad of key cellular regulatory processes. The loss of mitochondrial function is related to the pathogenesis of several human diseases. Over the last decades, an increasing number of studies have shown that dietary polyphenols can regulate mitochondrial redox status, and in some cases, prevent or delay disease progression. This paper aims to review the role of four dietary polyphenols - resveratrol, curcumin, epigallocatechin-3-gallate nd quercetin - in molecular pathways regulated by mitochondria and their potential impact on human health. Cumulative evidence showed that the aforementioned polyphenols improve mitochondrial functions in different in vitro and in vivo experiments. The mechanisms underlying the polyphenols' beneficial effects include, among others, the attenuation of oxidative stress, the regulation of mitochondrial metabolism and biogenesis and the modulation of cell-death signaling cascades, among other mitochondrial-independent effects. The understanding of the chemicalbiological interactions of dietary polyphenols, namely with mitochondria, may have a huge impact on the treatment of mitochondrial dysfunction-related disorders.

Resveratrol-loaded PLGA nanoparticles: enhanced stability, solubility and bioactivity of resveratrol for non-alcoholic fatty liver disease therapy

Resveratrol (3, 4', 5-trihydroxy-trans-stilbene, RSV), a nutraceutical, has recently attracted lots of attention because of its outstanding pharmacological potential. The effects of RSV on non-alcoholic fatty liver disease (NAFLD) remain inconclusive, although a wealth of research has been done. The major obstacle presented was RSV's poor bioavailability due to its poor aqueous solubility, chemical instability and intestinal metabolism. In this study, nanotechnology was used to encapsulate RSV to enhance its stability, water solubility and bioactivity, which can be used to treat NAFLD by HepG2 hepatocytes-induced in vitro. RSV-loaded poly (d, l-lactide-co-glycolide acid) (PLGA) nanoparticles (RSV-PLGA-NPs) were prepared according to an oil/water (O/W) emulsion technique. The RSV-PLGA-NPs were of spherical morphology with an average size of 176.1 nm and a negative charge of -22.6 mV. These nanoparticles exhibited remarkable encapsulation efficiency (EE%) (97.25%) and drug loading (14.9%) for RSV. A sustained RSV release from RSV-PLGA-NPs could be achieved especially in acidic conditions when simulating transporting through the gastrointestinal tract. In addition, these nanoparticles were stable enough to store at 4°C for a least six months with unchanged EE%. Moreover, RSV-PLGA-NPs were more efficient in alleviating lipogenesis, promoting lipolysis and reducing hepatocellular proliferation than free RSV due to its improved stability, water solubility and bioactivity. These findings indicated that the RSV-PLGA-NPs provided superb and stable drug delivery with small particle size, high capsulation efficiency, well-controlled drug release, which greatly enhanced the stability, water solubility and bioactivity. Besides, the discovery that the inhibitory effect of RSV-PLGA-NPs on hepatocellular proliferation and lipid accumulation in steatotic HepG2 cells may provide a new way to study the mechanism of NAFLD. Therefore, RSV-PLGA-NPs have a promising potential for NAFLD therapy.

Regression of Nonalcoholic Fatty Liver Disease with Zinc and Selenium Co-supplementation after Disease Progression in Rats

BACKGROUND

Studies have shown that zinc and selenium deficiency is common in nonalcoholic fatty liver disease (NAFLD). However, the effects of zinc and selenium co-supplementation before and/or after disease progression on NAFLD are not clear enough. The aim of this study was to compare the effects of zinc and selenium co-supplementation before and/or after disease progression on NAFLD prognosis.

MATERIALS AND METHODS

Forty male Sprague-Dawley rats (197±4 g) were randomly assigned to 4 dietary groups: normal-fat diet (NFD; receiving 9% of calories as fat), high-fat diet (HFD; receiving 82% of calories as fat), supplementation before disease progression (S+HFD), and supplementation after disease progression (HFD+S). The diets were implemented over a 20-week period in all the groups. Biochemical and histologic parameters were compared between the 4 groups, and between-group comparisons were also carried out.

RESULTS

There were significant differences in the average food dietary intake (P<0.001), weight (P<0.001), fasting blood sugar (P=0.005), triglyceride (P<0.001), total cholesterol (P<0.001), low-density lipoprotein cholesterol (P=0.002), high-density lipoprotein cholesterol (P=0.001), alanine aminotransferase (P<0.001), and aspartate aminotransferase (P<0.001) between the 4 dietary groups. Serum triglyceride and total cholesterol were significantly lower in the HFD+S Group than in the S+HFD Group (P<0.001 and P=0.003, respectively). Fat accumulation was significantly reduced in the HFD+S Group (P<0.001).

CONCLUSION

Zinc and selenium co-supplementation after disease progression improved biochemical and histologic parameters in an experimental model of NAFLD.

Regulation of hepcidin expression by inflammation-induced activin B

Activin B is induced in response to inflammation in the liver and enhances hepcidin expression, but the source of activin B and the molecular mechanism underlying hepcidin induction are not clear yet. Lipopolysaccharide (LPS)-induced inflammation induced inhibin βB but not inhibin α or inhibin βA expression in the liver, implicating activin B induction. Immunoreactive inhibin βB was detected in endothelial cells and Kupffer cells in LPS-treated liver. Activin B, but not activin A or activin AB, directly increased hepcidin expression. Activin B induced phosphorylation and activation of Smad1/5/8, the BMP-regulated (BR)-Smads. The stimulation of hepcidin transcription by activin B was mediated by ALK2 and ActRIIA, receptors for the TGF-β family. Unexpectedly, activin B-induced hepcidin expression and BR-Smad phosphorylation were resistant to the effects of LDN-193189, an ALK2/3/6 inhibitor. ALK2 and ActRIIA complex formation in response to activin B may prevent the approach of LDN-193189 to ALK2 to inhibit its activity. Activin B also induced phosphorylation of Smad2/3, the TGF-β/activin-regulated (AR)-Smad, and increased expression of connective tissue growth factor, a gene related to liver fibrogenesis, through ALK4 and ActRIIA/B. Activin B-induced activation of the BR-Smad pathway was also detected in non-liver-derived cells. The present study reveals the broad signaling of activin B, which is induced in non-parenchymal cells in response to hepatic inflammation, in hepatocytes.

Herbal medicines and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), which is characterized by excessive fat accumulation in the liver of patients who consume little or no alcohol, becomes increasingly common with rapid economic development. Long-term excess fat accumulation leads to NAFLD and represents a global health problem with no effective therapeutic approach. NAFLD is considered to be a series of complex, multifaceted pathological processes involving oxidative stress, inflammation, apoptosis, and metabolism. Over the past decades, herbal medicines have garnered growing attention as potential therapeutic agents to prevent and treat NAFLD, due to their high efficacy and low risk of side effects. In this review, we evaluate the use of herbal medicines (including traditional Chinese herbal formulas, crude extracts from medicinal plants, and pure natural products) to treat NAFLD. These herbal medicines are natural resources that can inform innovative drug research and the development of treatments for NAFLD in the future.

Knockdown of Astrocyte Elevated Gene-1 Inhibits Activation of Hepatic Stellate Cells

BACKGROUND

Astrocyte elevated gene-1 (AEG-1) is a positive regulator of tumorigenesis and a valuable prognostic marker of a diverse array of cancers, including liver cancer; however, the relationship between AEG-1 and hepatic fibrogenesis is not known.

OBJECTIVE

The objective of this study was to explore the expression of AEG-1 during hepatic fibrogenesis and determine how AEG-1 regulates the profibrogenic phenotype of hepatic stellate cells (HSCs).

METHODS

The levels of AEG-1 were monitored in the fibrotic livers and transforming growth factor-β (TGF-β)- or lipopolysaccharide (LPS)-stimulated HSCs. The expression of AEG-1 was knocked down by lentivirus-mediated short hairpin RNA in HSCs, and collagen expression, proliferation assays, apoptosis induction studies, and migration assays were simultaneously conducted in vitro.

RESULTS

AEG-1 expression was increased in the fibrotic livers. At the cellular level, TGF-β or LPS stimulation, which caused HSC activation, induced AEG-1 expression in HSC-T6 and primary rat HSCs (P < 0.05). Knockdown of AEG-1 inhibited collagen I and α-smooth muscle actin expression (P < 0.05), reduced cell proliferation (P < 0.05) and motility (P < 0.05), and induced cell apoptosis (P < 0.05) in HSCs. This antifibrotic effect caused by lack of AEG-1 was associated with the inactivation of PI3K/Akt and the mitogen-activated protein kinase pathway.

CONCLUSIONS

Knockdown of AEG-1 suppressed the activation of HSCs by modulating the phenotype and inducing apoptosis. AEG-1 might be a potential target in treatment of hepatic fibrosis.

The Glucagon-Like Peptide-1 Analogue Liraglutide Inhibits Oxidative Stress and Inflammatory Response in the Liver of Rats with Diet-Induced Non-alcoholic Fatty Liver Disease

Liraglutide, a glucagon-like peptide-1 (GLP-1) analogue, has been demonstrated to reduce hepatic steatosis. However, the mechanism of the lipid-lowering effect of liraglutide in the liver remains unclear. The aim of the present study was to investigate the beneficial effect of liraglutide on diet-induced non-alcoholic fatty liver disease (NAFLD) and the underlying mechanism in rats. NAFLD was induced in Sprague-Dawley rats by feeding a high fat and high cholesterol (HFHC) diet. Liraglutide (0.6 mg/kg body weight/d) was injected intraperitoneally to the rats subjected to HFHC diet four weeks before sacrificing the animals. Body and liver weight, fasting blood glucose (FBG), fasting insulin, serum aminotransferase (ALT) and lipid accumulation in the liver were determined. Markers of oxidative stress, such as malondialdehyde (MDA), free fatty acid (FFAs), superoxide dismutase (SOD), and pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) were detected by colorimetric detection or enzyme-linked immunosorbent assay (ELISA). Serum and hepatic adiponectin were measured by ELISA. The expression of c-Jun N-terminal kinase-1 (JNK-1) and phosphorylated JNK-1 were examined by Western blotting. Liraglutide improved insulin resistance, decreased hepatic steatosis and reversed liver dysfunction. The hepatic levels of MDA, FFAs, and TNF-α were significantly decreased versus controls. Meanwhile, administration of liraglutide significantly increased SOD and adiponectin levels in the liver and inhibited the expression of JNK-1 and phosphorylated JNK-1 versus control rats. Liraglutide exerted anti-oxidative and anti-inflammatory effects in the liver and consequently reversed hepatic steatosis and insulin resistance. Such effects might be mediated by the elevation of adiponectin levels and the inactivation of JNK-1.

Glucagon-like peptide-1 preserves non-alcoholic fatty liver disease through inhibition of the endoplasmic reticulum stress-associated pathway

AIM

Glucagon-like peptide-1 (GLP-1) has been increasingly recognized for treating diabetes mellitus, and for its potential to effectively treat non-alcoholic fatty liver disease (NAFLD). However, the mechanisms of GLP-1 induction in NAFLD are not completely known. We investigated whether GLP-1 can protect against NAFLD by alleviating endoplasmic reticulum (ER) stress.

METHODS

Male Sprague-Dawley rats were fed a high-fat diet and treated with a long-acting GLP-1 receptor agonist, liraglutide. Biochemical, morphological, genetic and protein expression of ER stress were investigated. In vitro, HepG2 cells were exposed to 0.4 mM palmitate fatty acid and treated with different concentrations of GLP-1, and ER protein 46 (ERp46) and ER stress pathways were analyzed. Cellular response to ER stress and apoptosis were determined upon transfection with either ERp46 siRNA or a negative control siRNA.

RESULTS

In vivo, the treatment of GLP-1 attenuated the hepatic accumulation of lipids, reduced inflammation and improved metabolic parameters. GLP-1 treatment significantly upregulated the expression of ERp46 and downregulated the ER stress marker. Activation of ER pathways was restrained by GLP-1. Similar observations were made in vitro. Furthermore, inhibition of ERp46 expression by siRNA-mediated silencing increased the ER stress response and enhanced cell apoptosis rates. In addition, GLP-1 could not reduce the levels of ER stress and apoptosis in cells transfected with ERp46 siRNA compared with in negative control transfected cells after palmitate treatment.

CONCLUSION

GLP-1 protected against NAFLD by inactivating the ER stress-associated apoptosis pathway. In addition, the effect was possibly related to the signaling pathway of ERp46.

The Dipeptidyl Peptidase-4 Inhibitor Teneligliptin Attenuates Hepatic Lipogenesis via AMPK Activation in Non-Alcoholic Fatty Liver Disease Model Mice

Non-alcoholic fatty liver disease (NAFLD), which is strongly associated with metabolic syndrome, is increasingly a major cause of hepatic disorder. Dipeptidyl peptidase (DPP)-4 inhibitors, anti-diabetic agents, are expected to be effective for the treatment of NAFLD. In the present study, we established a novel NAFLD model mouse using monosodium glutamate (MSG) and a high-fat diet (HFD) and investigated the effects of a DPP-4 inhibitor, teneligliptin, on the progression of NAFLD. Male MSG/HFD-treated mice were divided into two groups, one of which received teneligliptin in drinking water. Administration of MSG and HFD caused mice to develop severe fatty changes in the liver, but teneligliptin treatment improved hepatic steatosis and inflammation, as evaluated by the NAFLD activity score. Serum alanine aminotransferase and intrahepatic triglyceride levels were significantly decreased in teneligliptin-treated mice (p < 0.05). Hepatic mRNA levels of the genes involved in de novo lipogenesis were significantly downregulated by teneligliptin (p < 0.05). Moreover, teneligliptin increased hepatic expression levels of phosphorylated AMP-activated protein kinase (AMPK) protein. These findings suggest that teneligliptin attenuates lipogenesis in the liver by activating AMPK and downregulating the expression of genes involved in lipogenesis. DPP-4 inhibitors may be effective for the treatment of NAFLD and may be able to prevent its progression to non-alcoholic steatohepatitis.

Polyphenols and non-alcoholic fatty liver disease: impact and mechanisms

Non-alcoholic fatty liver disease (NAFLD) is considered to be the hepatic component of the metabolic syndrome and its prevalence is rapidly increasing due to its strong association with insulin resistance and obesity. At present, given that NAFLD is highly prevalent and therapies are limited, much attention is focused on identifying effective dietary strategies for the prevention and treatment of the disease. Polyphenols are a group of plant bioactive compounds whose regular consumption have been associated with a reduction in the risk of a number of metabolic disorders associated with NAFLD. Here we review the emerging and relatively consistent evidence from cell culture and rodent studies showing that select polyphenols positively modulate a variety of contributors to the NAFLD phenotype, through diverse and complementary mechanisms of action. In particular, the reduction of de novo lipogenesis (via sterol regulatory element-binding protein 1c) and increased fatty acid β-oxidation, presumably involving AMP-activated protein kinase activation, will be discussed. The indirect antioxidant and anti-inflammatory properties of polyphenols which have been reported to contribute to the amelioration of NAFLD will also be addressed. In addition to a direct study of the liver, rodent studies have provided insight into the impact of polyphenols on adipose tissue function and whole body insulin sensitivity, which are likely to in part modulate their impact on NAFLD development. Finally an overview of the limited data from clinical trials will be given along with a discussion of the dose extrapolation from animal studies to human subjects.

Resveratrol does not benefit patients with nonalcoholic fatty liver disease

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD), characterized by accumulation of hepatic triglycerides (steatosis), is associated with abdominal obesity, insulin resistance, and inflammation. Although weight loss via calorie restriction reduces features of NAFLD, there is no pharmacologic therapy. Resveratrol is a polyphenol that prevents high-energy diet-induced steatosis and insulin resistance in animals by up-regulating pathways that regulate energy metabolism. We performed a placebo-controlled trial to assess the effects of resveratrol in patients with NAFLD.

METHODS

Overweight or obese men diagnosed with NAFLD were recruited from hepatology outpatient clinics in Brisbane, Australia from 2011 through 2012. They were randomly assigned to groups given 3000 mg resveratrol (n = 10) or placebo (n = 10) daily for 8 weeks. Outcomes included insulin resistance (assessed by the euglycemic-hyperinsulinemic clamp), hepatic steatosis, and abdominal fat distribution (assessed by magnetic resonance spectroscopy and imaging). Plasma markers of inflammation, as well as metabolic, hepatic, and antioxidant function, were measured; transcription of target genes was measured in peripheral blood mononuclear cells. Resveratrol pharmacokinetics and safety were assessed.

RESULTS

Eight-week administration of resveratrol did not reduce insulin resistance, steatosis, or abdominal fat distribution when compared with baseline. No change was observed in plasma lipids or antioxidant activity. Levels of alanine and aspartate aminotransferases increased significantly among patients in the resveratrol group until week 6 when compared with the placebo group. Resveratrol did not significantly alter transcription of NQO1, PTP1B, IL6, or HO1 in peripheral blood mononuclear cells. Resveratrol was well-tolerated.

CONCLUSIONS

Eight weeks administration of resveratrol did not significantly improve any features of NAFLD, compared with placebo, but it increased hepatic stress, based on observed increases in levels of liver enzymes. Further studies are needed to determine whether agents that are purported to mimic calorie restriction, such as resveratrol, are safe and effective for complications of obesity. Clinical trials registration no: ACTRN12612001135808.

Effects of resveratrol in experimental and clinical non-alcoholic fatty liver disease

The prevalence of obesity and related conditions like non-alcoholic fatty liver disease (NAFLD) is increasing worldwide and therapeutic options are limited. Alternative treatment options are therefore intensively sought after. An interesting candidate is the natural polyphenol resveratrol (RSV) that activates adenosinmonophosphate-activated protein kinase (AMPK) and silent information regulation-2 homolog 1 (SIRT1). In addition, RSV has known anti-oxidant and anti-inflammatory effects. Here, we review the current evidence for RSV-mediated effects on NAFLD and address the different aspects of NAFLD and non-alcoholic steatohepatitis (NASH) pathogenesis with respect to free fatty acid (FFA) flux from adipose tissue, hepatic de novo lipogenesis, inadequate FFA β-oxidation and additional intra- and extrahepatic inflammatory and oxidant hits. We review the in vivo evidence from animal studies and clinical trials. The abundance of animal studies reports a decrease in hepatic triglyceride accumulation, liver weight and a general improvement in histological fatty liver changes, along with a reduction in circulating insulin, glucose and lipid levels. Some studies document AMPK or SIRT1 activation, and modulation of relevant markers of hepatic lipogenesis, inflammation and oxidation status. However, AMPK/SIRT1-independent actions are also likely. Clinical trials are scarce and have primarily been performed with a focus on overweight/obese participants without a focus on NAFLD/NASH and histological liver changes. Future clinical studies with appropriate design are needed to clarify the true impact of RSV treatment in NAFLD/NASH patients.

Risk of cardiovascular, cardiac and arrhythmic complications in patients with non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) has emerged as a public health problem of epidemic proportions worldwide. Accumulating clinical and epidemiological evidence indicates that NAFLD is not only associated with liver-related morbidity and mortality but also with an increased risk of coronary heart disease (CHD), abnormalities of cardiac function and structure (e.g., left ventricular dysfunction and hypertrophy, and heart failure), valvular heart disease (e.g., aortic valve sclerosis) and arrhythmias (e.g., atrial fibrillation). Experimental evidence suggests that NAFLD itself, especially in its more severe forms, exacerbates systemic/hepatic insulin resistance, causes atherogenic dyslipidemia, and releases a variety of pro-inflammatory, pro-coagulant and pro-fibrogenic mediators that may play important roles in the pathophysiology of cardiac and arrhythmic complications. Collectively, these findings suggest that patients with NAFLD may benefit from more intensive surveillance and early treatment interventions to decrease the risk for CHD and other cardiac/arrhythmic complications. The purpose of this clinical review is to summarize the rapidly expanding body of evidence that supports a strong association between NAFLD and cardiovascular, cardiac and arrhythmic complications, to briefly examine the putative biological mechanisms underlying this association, and to discuss some of the current treatment options that may influence both NAFLD and its related cardiac and arrhythmic complications.

The role of medications for the management of patients with NAFLD

The article is intended to provide an overview of the strengths and limits of controlled trials of pharmacologic treatment of nonalcoholic fatty liver disease. No drug has so far been approved, although validated on histologic outcomes. Several new drugs are under scrutiny, acting with different mechanisms along the chain of events from fatty liver to fibrosis, cirrhosis, and hepatocellular carcinoma. The article investigates which drug, if any, should be preferred for a tailored intervention in individual patients, according to age, comorbidities, and disease severity, and if treatment should be continued lifelong, to prevent disease progression and long-term occurrence of cirrhosis.

Regression of fibrosis and reversal of cirrhosis in rats by galectin inhibitors in thioacetamide-induced liver disease

Galectin-3 protein is critical to the development of liver fibrosis because galectin-3 null mice have attenuated fibrosis after liver injury. Therefore, we examined the ability of novel complex carbohydrate galectin inhibitors to treat toxin-induced fibrosis and cirrhosis. Fibrosis was induced in rats by intraperitoneal injections with thioacetamide (TAA) and groups were treated with vehicle, GR-MD-02 (galactoarabino-rhamnogalaturonan) or GM-CT-01 (galactomannan). In initial experiments, 4 weeks of treatment with GR-MD-02 following completion of 8 weeks of TAA significantly reduced collagen content by almost 50% based on Sirius red staining. Rats were then exposed to more intense and longer TAA treatment, which included either GR-MD-02 or GM-CT-01 during weeks 8 through 11. TAA rats treated with vehicle developed extensive fibrosis and pathological stage 6 Ishak fibrosis, or cirrhosis. Treatment with either GR-MD-02 (90 mg/kg ip) or GM-CT-01 (180 mg/kg ip) given once weekly during weeks 8–11 led to marked reduction in fibrosis with reduction in portal and septal galectin-3 positive macrophages and reduction in portal pressure. Vehicle-treated animals had cirrhosis whereas in the treated animals the fibrosis stage was significantly reduced, with evidence of resolved or resolving cirrhosis and reduced portal inflammation and ballooning. In this model of toxin-induced liver fibrosis, treatment with two galectin protein inhibitors with different chemical compositions significantly reduced fibrosis, reversed cirrhosis, reduced galectin-3 expressing portal and septal macrophages, and reduced portal pressure. These findings suggest a potential role of these drugs in human liver fibrosis and cirrhosis.

Linagliptin alleviates hepatic steatosis and inflammation in a mouse model of non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is a primary cause of cirrhosis and hepatocellular carcinoma. Dipeptidyl peptidase (DPP)-4 inhibitors are established therapies for type 2 diabetes and although DPP-4 inhibitors can reduce hepatic steatosis, their impact on local inflammation and fibrosis in NASH remains unknown. Using two different experimental treatment regimens (4- and 2-week treatments) in streptozotocin-treated neonatal mice on a high-fat diet, we show that the DPP-4 inhibitor linagliptin (10 and 30 mg/kg) significantly attenuated the NAS score from 4.9 ± 0.6 to 3.7 ± 0.4 and 3.6 ± 0.3, respectively, in the 4-week study. In the 2-week study, linagliptin 10 mg/kg significantly reduced NAS score from 4.1 ± 0.4 to 2.4 ± 0.4. Telmisartan was used as a positive control in both studies and lowered NAS score to 1.9 ± 0.7 and 1.4 ± 0.3, respectively. Due to streptozotocin treatment, elevated glucose levels were unchanged by either drug treatment. Further, linagliptin 10 mg/kg significantly reduced mRNA levels of SOCS-3 (from 1.68 ± 0.2 to 0.83 ± 0.08), IFN-γ (from 4.0 ± 0.5 to 2.3 ± 0.3), and TNF-α (from 5.7 ± 0.5 to 2.13 ± 0.3). The latter observation was confirmed by immunohistochemistry of TNF-α in liver specimens. In addition, using microautoradiography, we showed that the distribution of radiolabeled linagliptin was heterogeneous with the highest density associated with interlobular bile ducts and portal tracts (acini). In conclusion, these studies confirm that linagliptin has high exposure in hepatic tissue and has both anti-inflammatory and anti-steatotic activity in NASH.

Inhibition of Glutaminyl Cyclases alleviates CCL2-mediated inflammation of non-alcoholic fatty liver disease in mice

Inflammation is an integral part of non-alcoholic fatty liver disease (NAFLD), the most prevalent form of hepatic pathology found in the general population. In this context, recently we have examined the potential role of Glutaminyl Cyclases (QC and isoQC), and their inhibitors, in the maturation of chemokines, for example, monocyte chemoattractant protein 1 (MCP-1, CCL2), to generate their bioactive conformation. Catalysis by isoQC leads to the formation of an N-terminal pyroglutamate residue protecting CCL2 against degradation by aminopeptidases. This is of importance because truncated forms possess a reduced potential to attract immune cells. Since liver inflammation is characterized by the up-regulation of different chemokine pathways, and within this CCL2 is known to be a prominent example, we hypothesised that application of QC/isoQC inhibitors may alleviate liver inflammation by destabilizing CCL2. Therefore, we investigated the role of QC/isoQC inhibition, in comparison with the angiotensin receptor blocker Telmisartan, during development of pathology in a mouse model of non-alcoholic fatty liver disease. Application of a QC/isoQC inhibitor led to a significant reduction in circulating alanine aminotransferase and NAFLD activity score accompanied by an inhibitory effect on hepatocyte ballooning. Further analysis revealed a specific reduction of inflammation by decreasing the number of F4/80-positive macrophages, which is in agreement with the proposed CCL2-related mechanism of action of QC/isoQC inhibitors. Finally, QC/isoQC inhibitor application attenuated liver fibrosis as characterized by reduced collagen deposition in the liver parenchyma. Thus in conclusion, QC/isoQC inhibitors are a promising novel class of anti-non-alcoholic steatohepatitis drugs which have a comparable disease-modifying effect to that of Telmisartan, which is probably mediated via specific interference with a comparable monocyte/macrophage infiltration that occurs under inflammatory conditions.

Fatty liver Shionogi-ob/ob mouse: A new candidate for a non-alcoholic steatohepatitis model

AIM

The fatty liver Shionogi (FLS) mouse develops hereditary fatty liver without obesity. The FLS-ob/ob mouse made by transferring the leptin(ob) gene demonstrates several metabolic disorders and marked fat deposition in the liver. The aim was to evaluate which mouse model, the FLS or FLS-ob/ob, is more useful for non-alcoholic steatohepatitis research.

METHODS

FLS (n = 40) and FLS-ob/ob (n = 40) mice were fed a standard diet for 12, 24, 36 and 48 weeks, and then killed. The degree of fat deposition, oxidative stress, fibrosis and apoptosis were analyzed in the liver. Hepatic mRNA expression of fibrogenic and pro-inflammatory cytokines was measured.

RESULTS

FLS mice developed hepatic steatosis and slight fibrosis without obesity between 12 and 48 weeks of age. Conversely, FLS-ob/ob mice developed severe steatosis at 12 weeks of age, and steatohepatitis with increased oxidative stress and advanced fibrosis between 24 and 36 weeks of age. At 48 weeks of age, some FLS-ob/ob but not FLS mice, progressed to cirrhosis. Transforming growth factor-β1, connective tissue growth factor and tumor necrosis factor-α mRNA expression levels were greater in FLS-ob/ob than FLS mice between 24 and 48 weeks of age. The number of apoptotic cells in the liver was greater at 12 weeks of age in FLS mice and at 48 weeks of age in FLS-ob/ob mice.

CONCLUSION

FLS-ob/ob mice developed more severe steatohepatitis with fibrosis than FLS mice, and had increased oxidative stress and apoptosis. These findings indicate that the FLS-ob/ob mouse is a more useful model for steatohepatitis research.

Diabetes and nonalcoholic Fatty liver disease: a pathogenic duo

Recent data increasingly support a complex interplay between the metabolic condition diabetes mellitus and the pathologically defined nonalcoholic fatty liver disease (NAFLD). NAFLD predicts the development of type 2 diabetes and vice versa, and each condition may serve as a progression factor for the other. Although the association of diabetes and NAFLD is likely to be partly the result of a "common soil," it is also probable that diabetes interacts with NAFLD through specific pathogenic mechanisms. In particular, through interrelated metabolic pathways currently only partly understood, diabetes appears to accelerate the progression of NAFLD to nonalcoholic steatohepatitis, defined by the presence of necroinflammation, with varying degrees of liver fibrosis. In the research setting, obstacles that have made the identification of clinically significant NAFLD, and particularly nonalcoholic steatohepatitis, difficult are being addressed with the use of new imaging techniques combined with risk algorithms derived from peripheral blood profiling. These techniques are likely to be used in the diabetes population in the near future. This review examines the pathogenic links between NAFLD and diabetes by exploring the epidemiological evidence in humans and also through newer animal models. Emerging technology to help screen noninvasively for differing pathological forms of NAFLD and the potential role of preventive and therapeutic approaches for NAFLD in the setting of diabetes are also examined.

Randomized double-blind placebo-controlled trial of powdered Brassica rapa ethanol extract on alteration of body composition and plasma lipid and adipocytokine profiles in overweight subjects

We evaluated the effects of Brassica rapa ethanol extract (BREE) on body composition and plasma lipid profiles through a randomized, double-blind, and placebo-controlled trial in overweight subjects. Fifty-eight overweight participants (age 20-50 years, body mass index23.0-24.9) were randomly assigned to two groups and served BREE (2 g/day) or placebo (starch, 2 g/day) for 10 weeks. Body compositions, nutrients intake, plasma lipids, adipocytokines, and hepatotoxicity biomarkers were assessed in all subjects at baseline and after 10 weeks of supplementation. The plasma total cholesterol (total-C) concentration was significantly increased after 10 weeks compared to the baseline in both groups. However, BREE supplementation significantly increased the high-density lipoprotein cholesterol (HDL-C) concentration and significantly reduced the total-C/HDL-C ratio, free fatty acid, and adipsin levels after 10 weeks. No significant differences were observed in body compositions, fasting blood glucose, plasma adipocytokines except adipsin, and aspartate aminotransferase and alanine aminotransferase activities between before and after trial within groups as well as between the two groups. The supplementation of BREE partially improves plasma lipid metabolism in overweight subjects without adverse effects.

Telmisartan attenuates hepatic fibrosis in bile duct-ligated rats

AIM

To evaluate the antifibrotic effect of telmisartan, an angiotensin II receptor blocker, in bile duct-ligated rats.

METHODS

Adult Sprague-Dawley rats were allocated to 3 groups: sham-operated rats, model rats underwent common bile duct ligation (BDL), and BDL rats treated with telmisartan (8 mg/kg, po, for 4 weeks). The animals were sacrificed on d 29, and liver histology was examined, the Knodell and Ishak scores were assigned, and the expression of angiotensin-converting enzyme (ACE) and ACE2 was evaluated with immunohistochemical staining. The mRNAs and proteins associated with liver fibrosis were evaluated using RTQ-PCR and Western blot, respectively.

RESULTS

The mean fibrosis score of BDL rats treated with telmisartan was significantly lower than that of the model rats (1.66±0.87 vs 2.13±0.35, P=0.015). However, there was no significant difference in inflammation between the two groups, both of which showed moderate inflammation. Histologically, treatment with telmisartan significantly ameliorated BDL-caused the hepatic fibrosis. Treatment with telmisartan significantly upregulated the mRNA levels of ACE2 and MAS, and decreased the mRNA levels of ACE, angiotensin II type 1 receptor (AT1-R), collagen type III, and transforming growth factor β1 (TGF-β1). Moreover, treatment with telmisartan significantly increased the expression levels of ACE2 and MAS proteins, and inhibited the expression levels of ACE and AT1-R protein.

CONCLUSION

Telmisartan attenuates liver fibrosis in bile duct-ligated rats via increasing ACE2 expression level.

Dipeptidylpeptidase--IV, a key enzyme for the degradation of incretins and neuropeptides: activity and expression in the liver of lean and obese rats

Given the scarcity of donors, moderately fatty livers (FLs) are currently being considered as possible grafts for orthotopic liver transplantation (OLT), notwithstanding their poor tolerance to conventional cold preservation. The behaviour of parenchymal and sinusoidal liver cells during transplantation is being studied worldwide. Much less attention has been paid to the biliary tree, although this is considered the Achille's heel even of normal liver transplantation. To evaluate the response of the biliary compartment of FLs to the various phases of OLT reliable markers are necessary. Previously we demonstrated that Alkaline Phosphatase was scarcely active in bile canaliculi of FLs and thus ruled it out as a marker. As an alternative, dipeptidylpeptidase-IV (DPP-IV), was investigated. This ecto-peptidase plays an important role in glucose metabolism, rapidly inactivating insulin secreting hormones (incretins) that are important regulators of glucose metabolism. DPP-IV inhibitors are indeed used to treat Type II diabetes. Neuropeptides regulating bile transport and composition are further important substrates of DPP-IV in the enterohepatic axis. DPP-IV activity was investigated with an azo-coupling method in the liver of fatty Zucker rats (fa/fa), using as controls lean Zucker (fa/+) and normal Wistar rats. Protein expression was studied by immunofluorescence with the monoclonal antibody (clone 5E8). In Wistar rat liver, DPP-IV activity and expression were high in the whole biliary tree, and moderate in sinusoid endothelial cells, in agreement with the literature. Main substrates of DPP-IV in hepatocytes and cholangiocytes could be incretins GLP-1 and GIP, and neuropeptides such as vasoactive intestinal peptide (VIP) and substance P, suggesting that these substances are inactivated or modified through the biliary route. In lean Zucker rat liver the enzyme reaction and protein expression patterns were similar to those of Wistar rat. In obese rat liver the patterns of DPP-IV activity and expression in hepatocytes reflected the morphological alterations induced by steatosis as lipid-rich hepatocytes had scarce activity, located either in deformed bile canaliculi or in the sinusoidal and lateral domains of the plasma membrane. These findings suggest that bile canaliculi in steatotic cells have an impaired capacity to inactivate incretins and neuropeptides. Incretin and/or neuropeptide deregulation is indeed thought to play important roles in obesity and insulin-resistance. No alteration in enzyme activity and expression was found in the upper segments of the biliary tree of obese respect to lean Zucker and Wistar rats. In conclusion, this research demonstrates that DPP-IV is a promising in situ marker of biliary functionality not only of normal but also of fatty rats. The approach, initially devised to investigate the behaviour of the liver during the various phases of transplantation, appears to have a much higher potentiality as it could be further exploited to investigate any pathological or stressful conditions involving the biliary tract (i.e., metabolic syndrome and cholestasis) and the response of the biliary tract to therapy and/or to surgery.

Resveratrol up-regulates hepatic uncoupling protein 2 and prevents development of nonalcoholic fatty liver disease in rats fed a high-fat diet

Obesity is associated with a markedly increased risk of nonalcoholic fatty liver disease. The anti-inflammatory polyphenol resveratrol possess promising properties in preventing this metabolic condition by dampening the pathological inflammatory reaction in the hepatic tissue. However, in the current study, we hypothesize that the beneficial effect of resveratrol is not solely attributable to its anti-inflammatory potential. Eight-week-old male Wistar rats were randomly distributed into 3 groups of 12 animals each: control diet (C), high-fat diet (HF), and HF supplemented with 100 mg resveratrol daily (HFR). After 8 weeks of dietary treatment, the rats were euthanized and relevant tissues were prepared for subsequent analysis. Resveratrol prevented the high fat-induced steatosis assessed by semiquantitative grading, which furthermore corresponded with a complete normalization of the hepatic triglyceride content (P < .001), despite no change in total body fat. In HFR, the hepatic uncoupling protein 2 expression was significantly increased by 76% and 298% as compared with HF and C, respectively. Moreover, the hepatic mitochondria content in HFR was significantly higher as compared with both C and HF (P < .001 and P = .004, respectively). We found no signs of hepatic inflammation, hereby demonstrating that resveratrol protects against fatty liver disease independently of its proposed anti-inflammatory potential. Our data might indicate that an increased number of mitochondria and, particularly, an increase in hepatic uncoupling protein 2 expression are involved in normalizing the hepatic fat content due to resveratrol supplementation in rodents fed a high-fat diet.

Nonalcoholic fatty liver disease and lipids

PURPOSE OF REVIEW

This article reviews the mechanisms leading to the development of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) and the effects of hypoglycaemic and lipid-lowering therapies on NAFLD/NASH.

RECENT FINDINGS

The interaction of lipogenesis, fatty acid oxidation, inflammation, endoplasmic reticulum stress and hepatic insulin resistance contribute to the pathogenesis of NAFLD/NASH. Few large scale clinical trials exist with biopsy or magnetic resonance endpoints as opposed to ultrasonographic and transaminase endpoints. Trial evidence that exists supports the utility of weight loss, metformin, thiazolidinediones, fibrates, niacin, ezetimibe and statins in improving the steatosis component of NAFLD/NASH though with less or minimal effects on the fibrotic component of NASH.

SUMMARY

Hypoglycaemic and lipid-lowering therapies may have a role in the treatment of NAFLD/NASH but large scale endpoint trials remain to be performed.

Circulating microparticles as disease-specific biomarkers of severity of inflammation in patients with hepatitis C or nonalcoholic steatohepatitis

BACKGROUND & AIMS

Microparticles released into the bloodstream upon activation or apoptosis of CD4(+) and CD8(+) T cells correlate with inflammation as determined by histologic analysis in patients with chronic hepatitis C (CHC). Patients with nonalcoholic fatty liver (NAFL) or nonalcoholic steatohepatitis (NASH) can be differentiated from those with CHC based on activation of distinct sets of immune cells in the liver.

METHODS

We compared profiles of circulating microparticles from patients with NAFL and NASH (n = 67) to those of CHC (n = 42), with healthy individuals (controls) using flow cytometry; the profiles were correlated with inflammation grade and fibrosis stage based on histologic analyses. We assessed the ability of the profiles to determine the severity of inflammation and fibrosis based on serologic and histologic analyses.

RESULTS

Patients with CHC had increased levels of microparticles from CD4(+) and CD8(+) T cells; the levels correlated with disease severity based on histologic analysis and levels of alanine aminotransferase. Patients with NAFL or NASH had significant increases in numbers of microparticles from invariant natural killer T cells and macrophages/monocytes (CD14(+)), which mediate pathogenesis of NASH. Microparticles from CD14(+) and invariant natural killer T cells correlated with levels of alanine aminotransferase and severity of NASH (based on histology). Levels of microparticles could differentiate between patients with NAFL or NASH and those with CHC, or either group of patients and controls (area under the receiver operating characteristic curves ranging from 0.56 to 0.99).

CONCLUSIONS

Quantification of immune cell microparticles from serum samples can be used to assess the extent and characteristics of hepatic inflammation in patients with chronic liver disease.

Incretin-based therapies--review of the physiology, pharmacology and emerging clinical experience

Diabetes therapies based on manipulation of the incretin system are now widely available, with millions of people receiving treatment. The incretin hormones, glucose-dependent insulinotropic peptide and glucagon-like peptide-1 are released from endocrine cells in the small intestinal mucosa primarily in response to oral nutrient ingestion. They have various effects, but those most relevant to metabolic dysfunction include stimulation of insulin and suppression of glucagon secretion, with resultant reduction in fasting and postprandial glucose. Incretin secretion and/or action is impaired in type 2 diabetes, leading to development of strategies aimed at redressing this abnormality. These strategies include pharmacological inhibition of dipeptidyl peptidase-4, the enzyme responsible for the short half-life of endogenous incretins, and administration of long-acting dipeptidyl peptidase-4-resistant peptides that bind to and activate the glucagon-like peptide-1 receptor. In this review, we address aspects of incretin biology and pharmacotherapy with a view to highlighting potentially clinically relevant issues and areas of basic research that may impinge on these.

Nonalcoholic steatohepatitis: the therapeutic challenge of a global epidemic

PURPOSE OF REVIEW

Nonalcoholic fatty liver (NAFL) and especially its inflammatory variant nonalcoholic steatohepatitis (NASH) have become a major challenge to healthcare systems worldwide because of the increasing prevalence of its major risk factors obesity and type 2 diabetes, which are closely linked to overeating, physical inactivity, and the metabolic syndrome.

RECENT FINDINGS

Between 10 and 20% of patients with NAFL develop NASH, which can progress to cirrhosis, end-stage liver disease, and hepatocellular carcinoma. The overall mortality in these patients is significantly increased because of both cardiovascular and liver-related complications. Sustained weight loss by diet and exercise, which is the most effective therapeutic measure, is only achieved by a minority of patients, having led to a great yet unmet need for medical therapies of NASH.

SUMMARY

Pharmacological therapies should target the underlying pathophysiology that involves insulin resistance, enhanced peripheral lipolysis and release of free fatty acids, oxidative stress, accumulation of toxic lipids, adipose tissue inflammation, sensitization of hepatocytes toward apoptotic cell death, and fibrogenesis. However, pharmacological therapy that is well tolerated, cost-effective, and poses an acceptable risk-to-benefit ratio has still to be identified. This review summarizes the current and promising treatment options and their implications for future research and clinical practice.

Intravenous administration of multipotent stromal cells prevents the onset of non-alcoholic steatohepatitis in obese mice with metabolic syndrome

BACKGROUND & AIMS

Metabolic syndrome is secondary to obesity and characterized by dyslipidemia, insulin resistance, and hypertension. Non-alcoholic fatty liver disease is its hepatic manifestation, whose progression-limiting step is non-alcoholic steatohepatitis (NASH). The latter is characterized by lipid accumulation, hepatocyte damage, leukocyte infiltration, and fibrosis. NASH is a prodrome to cirrhosis and hepatocellular carcinoma. Multipotent stromal cells (MSCs) have been shown to be immunomodulatory and contribute to liver regeneration in acute failure conditions. Our aim was to evaluate whether MSC administration prevents the onset of NASH in obese mice with metabolic syndrome.

METHODS

C57BL/6 mice were chronically fed with high-fat diet. At week 33, mice received intravenously either the vehicle (obese untreated) or two doses of 0.5×10(6) syngeneic MSCs (obese MSC-treated). Four months later, liver function and structure, and metabolic syndrome markers were assessed. The persistence of donor MSCs(GFP) in obese mice was evaluated 17 weeks after their administration.

RESULTS

Obese untreated mice presented high plasma levels of hepatic enzyme, hepatomegaly, liver fibrosis, inflammatory cell infiltration, and hepatic triglyceride accumulation. Furthermore, they showed high expression levels of fibrosis markers and pro-inflammatory cytokines. By contrast, obese MSC-treated mice only presented steatosis. Mice kept obese, hypercholesterolemic, hyperglycemic, and insulin resistant irrespective of whether they received MSCs or not. Donor MSCs(GFP) were found in liver, bone marrow, heart, and kidney of obese mice.

CONCLUSIONS

MSC administration prevents the onset of NASH in obese mice. Observed hepatoprotection is not related to a reversion of the metabolic syndrome but to the preclusion of the inflammatory process.

Treatment of atherogenic liver based on the pathogenesis of nonalcoholic fatty liver disease: a novel approach to reduce cardiovascular risk?

Nonalcoholic fatty liver disease (NAFLD), which spans a spectrum of conditions ranging from simple steatosis to progressive nonalcoholic steatohepatitis (NASH), is the most common chronic liver disease and a relevant public health issue. The prevalence of NAFLD depends on adiposity, age, gender and ethnicity. The natural history of liver disease in those with NAFLD critically depends on liver histological changes. However, cardiovascular mortality is increased in NAFLD, particularly in middle-aged adults. Against such a background, this review consists of three sections. First, data on NAFLD as a novel mechanism of increased cardiovascular risk via hyperinsulinism, pro-thrombotic potential, and subclinical inflammation are summarized. Next, the role of atherogenic liver in the development of manifestations of oxidative stress and atherosclerosis is emphasized. Finally, whether and how treating NAFLD will mechanistically result in reduced cardiovascular risk through ameliorated metabolic syndrome is discussed.

Insulin resistance in nonalcoholic steatohepatitis: necessary but not sufficient - death of a dogma from analysis of therapeutic studies?

Studies on pathogenesis tend to blame insulin resistance as the chief pathogenic agent in the development and progression of nonalcoholic steatohepatitis (NASH). In this article, studies reporting histological changes induced by pharmacological therapy and nonpharmacological interventions in NASH are critically reviewed, assuming that analysis of morphological findings can provide further insight into the pathogenesis of NASH. PubMed database analysis provided 16 studies describing light microscopy in adults and three in children; ultrastructural analysis was conducted through electron microscopy in two human and four animal studies. Analysis of the data disclosed methodological issues, such as variable histological criteria, limited series, failure to stratify enrolled patients for their risk of progression and very few electron microscopy studies. Moreover, no particularly convincing 'proof-of-concept' study that might assist in understanding the pathogenesis of NASH was found. It is noteworthy that insulin sensitizers fail to treat NASH in all cases, do not reverse or even worsen mitochondrial abnormalities in NASH and, conversely, histological improvement of disease, at least in some patients, is observed with agents acting through mechanisms other than insulin sensitization, such as vitamin E. The finding that correction of insulin resistance may not be sufficient to successfully treat NASH in the majority of patients seems to conflict with studies on pathogenesis. This might imply that NASH is the shared end result of varying pathogenic mechanisms concurring to determine liver damage to a variable extent in the individual patients. If this hypothesis is true, we should try to tailor treatment to each subject.

Increased liver uptake and reduced hepatic stellate cell activation with a cell-specific conjugate of the Rho-kinase inhibitor Y27632

Purpose

Rho-kinase regulates activation of hepatic stellate cells (HSC) during liver fibrosis, but the ubiquitous presence of this kinase may hinder examination of its exact role and the therapeutic use of inhibitors. We therefore coupled the Rho-kinase inhibitor Y27632 to a drug carrier that binds the mannose-6-phosphate insulin-like growth factor II (M6P/IGFII)-receptor which is upregulated on activated HSC.

Methods

Y27632 was coupled to mannose-6-phosphate human serum albumin (M6PHSA), and in vitro experiments were performed on primary rat HSC. Biodistribution and effect studies were performed in an acute CCl₄ model in mice.

Results

Y27-conjugate remained stable in serum, while drug was efficiently released in liver homogenates. Receptor-blocking studies revealed that it was specifically taken up through the M6P/IGFII-receptor on fibroblasts, and it inhibited expression of fibrotic markers in activated HSC. In vivo, liver drug levels were significantly higher after injection of Y27-conjugate as compared to Y27632, and the conjugate accumulated specifically in HSC. After acute CCl₄-induced liver injury, Y27-conjugate reduced the local activation of HSC, whereas an equimolar dose of free drug did not.

Conclusions

We conclude that specific targeting of a Rho-kinase inhibitor to HSC leads to enhanced accumulation of the drug in HSC, reducing early fibrogenesis in the liver.

Electronic Supplementary Material

The online version of this article (doi:10.1007/s11095-011-0430-9) contains supplementary material, which is available to authorized users.