Angiotensin II type 1 receptor blocker inhibits fibrosis in rat nonalcoholic steatohepatitis

Emerging drugs for the treatment of hepatic fibrosis on nonalcoholic steatohepatitis

INTRODUCTION

Approved drug therapies for nonalcoholic steatohepatitis (NASH) are lacking, for which various agents are currently being tested in clinical trials. Effective drugs for liver fibrosis, the factor most associated with prognosis in NASH, are important.

AREAS COVERED

This study reviewed the treatment of NASH with a focus on the effects of existing drugs and new drugs on liver fibrosis.

EXPERT OPINION

Considering the complex pathophysiology of fibrosis in NASH, drug therapy may target multiple pathways. The method of assessing fibrosis is important when considering treatment for liver fibrosis in NASH. The Food and Drug Administration considers an important fibrosis endpoint to be histological improvement in at least one fibrosis stage while preventing worsening of fatty hepatitis. To obtain approval as a drug for NASH, efficacy needs to be demonstrated on endpoints such as liver-related events and myocardial infarction. Among the current therapeutic agents for NASH, thiazolidinedione, sodium-glucose co-transporter 2, and selective peroxisome proliferator-activated receptors α modulator have been reported to be effective against fibrosis, although further evidence is required. The effects of pan-peroxisome proliferator-activated receptors, obeticholic acid, and fibroblast growth factor-21 analogs on liver fibrosis in the development stage therapeutics for NASH are of particular interest.

The Renin-Angiotensin System in Liver Disease

The renin-angiotensin system (RAS) is a complex homeostatic entity with multiorgan systemic and local effects. Traditionally, RAS works in conjunction with the kidney to control effective arterial circulation, systemic vascular resistance, and electrolyte balance. However, chronic hepatic injury and resulting splanchnic dilation may disrupt this delicate balance. The role of RAS in liver disease, however, is even more extensive, modulating hepatic fibrosis and portal hypertension. Recognition of an alternative RAS pathway in the past few decades has changed our understanding of RAS in liver disease, and the concept of opposing vs. "rebalanced" forces is an ongoing focus of research. Whether RAS inhibition is beneficial in patients with chronic liver disease appears to be context-dependent, but further study is needed to optimize clinical management and reduce organ-specific morbidity and mortality. This review presents the current understanding of RAS in liver disease, acknowledges areas of uncertainty, and describes potential areas of future investigation.

Angiotensin-converting enzyme inhibitory peptide IVGFPAYGH protects against liver injury in mice fed a high‑sodium diet by inhibiting the RAS and remodeling gut microbial communities

Consuming a high‑sodium diet carries serious health risks and significantly influences the activation state of the renin-angiotensin system (RAS). This study evaluates the protective effect of angiotensin-converting enzyme (ACE) inhibitory peptide IVGFPAYGH on a high‑sodium diet-induced liver injury. IVGFPAYGH supplementation increased the activities of liver antioxidase and decreased the levels of liver inflammatory factor in mice fed a high‑sodium diet (8 % NaCl). IVGFPAYGH supplementation also reduced liver fatty acid synthesis and promoted fatty acid oxidation, increased the expression of low-density lipoprotein receptor, and improved liver dyslipidemia. Furthermore, IVGFPAYGH supplementation inhibited the activation of the liver RAS via inhibiting ACE activity and reducing angiotensin II levels in mice fed a high‑sodium diet. Moreover, IVGFPAYGH supplementation could alter the gut microbiota composition toward a normal gut microbiota composition and increase the abundance of the Lactobacillus genus. IVGFPAYGH supplementation also increased the expression levels of small intestinal tight junction protein and cecum short-chain fatty acids. Thus, IVGFPAYGH supplementation may maintain intestinal homeostasis and improve high‑sodium diet-induced liver injury by altering the gut microbiota composition and inhibiting the RAS. IVGFPAYGH is a promising functional ingredient for protecting liver damage caused by a high‑sodium diet.

The Role of Tumor Necrosis Factor-Alpha in the Pathogenesis and Treatment of Nonalcoholic Fatty Liver Disease

PURPOSE OF REVIEW

To summarize experimental and clinical evidence on the association between tumor necrosis factor-α (TNF-α) and nonalcoholic fatty liver disease (NAFLD) and discuss potential treatment considerations.

RECENT FINDINGS

Experimental evidence suggests that TNF-α is a cytokine with a critical role in the pathogenesis of NAFLD. Although, the production of TNF-α may be an early event during the course of nonalcoholic fatty liver (NAFL), TNF-α may play a more substantial role in the pathogenesis of nonalcoholic steatohepatitis (NASH) and NAFLD-associated fibrosis. Moreover, TNF-α may potentiate hepatic insulin resistance, thus interconnecting inflammatory with metabolic signals and possibly contributing to the development of NAFLD-related comorbidities, including cardiovascular disease, hepatocellular carcinoma, and extra-hepatic malignancies. In clinical terms, TNF-α is probably associated with the severity of NAFLD; circulating TNF-α gradually increases from controls to patients with NAFL, and then, to patients with NASH. Given this potential association, various therapeutic interventions (obeticholic acid, peroxisome proliferator-activated receptors, sodium-glucose co-transporter 2 inhibitors, glucagon-like peptide-1 receptor agonists, probiotics, synbiotics, rifaximin, vitamin E, pentoxifylline, ursodeoxycholic acid, fibroblast growth factor-21, n-3 polyunsaturated fatty acids, statins, angiotensin receptor blockers) have been evaluated for their effect on TNF-α and NAFLD. Interestingly, anti-TNF biologics have shown favorable metabolic and hepatic effects, which may open a possible therapeutic window for the management of advanced NAFLD. The potential key pathogenic role of TNF-α in NAFLD warrants further investigation and may have important diagnostic and therapeutic implications.

Non-Alcoholic Fatty Liver Disease as an Emerging Risk Factor for Heart Failure

PURPOSE OF THE REVIEW

Non-alcoholic fatty liver disease (NAFLD) and heart failure (HF) are two chronic diseases that have become important global public health problems. This narrative review provides a comprehensive overview of the association between NAFLD and increased risk of new-onset HF, briefly discusses the putative biological mechanisms linking these two conditions, and summarizes targeted pharmacotherapies for NAFLD that might also beneficially affect cardiac complications leading to new-onset HF.

RECENT FINDINGS

Recent observational cohort studies supported a significant association between NAFLD and the long-term risk of new-onset HF. Notably, this risk remained statistically significant even after adjustment for age, sex, ethnicity, adiposity measures, pre-existing type 2 diabetes and other common cardiometabolic risk factors. In addition, the risk of incident HF was further increased with more advanced liver disease, especially with higher severity of liver fibrosis. There are multiple potential pathophysiological mechanisms by which NAFLD (especially in its more advanced forms) may increase the risk of new-onset HF. Because of the strong link existing between NAFLD and HF, more careful surveillance of these patients will be needed. However, further prospective and mechanistic studies are required to better decipher the existing but complex link between NAFLD and risk of new-onset HF.

Spontaneous Epiretinal Membrane Resolution and Angiotensin Receptor Blockers: Case Observation, Literature Review and Perspectives

INTRODUCTION

Epiretinal membrane (ERM) is a relatively common condition affecting the macula. When symptoms become apparent and compromise a patient's quality of vision, the only therapeutic approach available today is surgery with a vitrectomy and peeling of the ERM. Angiotensin receptor blockers (ARBs) and angiotensin-converting enzyme inhibitors (ACE-Is) reduce the effect of angiotensin II, limit the amount of fibrosis, and demonstrate consequences on fibrinogenesis in the human body. Case Description and Materials and Methods: A rare case of spontaneous ERM resolution with concomitant administration of ARB is reported. The patient was set on ARB treatment for migraines and arterial hypertension, and a posterior vitreous detachment was already present at the first diagnosis of ERM. The scientific literature addressing the systemic relationship between ARB, ACE-Is, and fibrosis in the past 25 years was searched in the PubMed, Medline, and EMBASE databases.

RESULTS

In total, 38 and 16 original articles have been selected for ARBs and ACE-Is, respectively, in regard to fibrosis modulation.

CONCLUSION

ARBs and ACE-Is might have antifibrotic activity on ERM formation and resolution. Further clinical studies are necessary to explore this phenomenon.

Altered local RAS in the liver increased the risk of NAFLD in male mouse offspring produced by in vitro fertilization

BACKGROUND

Assisted reproductive technology (ART) is associated with an increased risk of adverse metabolic health in offspring, and these findings have been demonstrated in animal models without parental infertility issues. However, it is unclear what changes lead to abnormal metabolism. The activation of the renin-angiotensin system (RAS) has been related to various aspects of metabolic syndrome. Thus, we focused on the local RAS of the liver, which is the central organ for glucose and lipid metabolism in offspring conceived by in vitro fertilization (IVF), and studied the role of local liver RAS in metabolic diseases.

METHODS

Male C57BL/6 mouse offspring obtained by natural pregnancy and IVF were fed a standard chow diet or a high-fat diet (HFD) from 4 weeks of age through 16 weeks of age. We assessed glucose and lipid metabolism, hepatic histopathology, and the gene and protein expression of key RAS components. In addition, the blocker losartan was used from 4 weeks of age through 16 weeks of age to investigate the regulatory mechanisms of abnormal local RAS on metabolic activity in the IVF offspring liver.

RESULTS

The growth trajectories of IVF offspring body and liver weights were different from those of naturally pregnant offspring. Impaired glucose tolerance (IGT) and insulin resistance (IR) occurred in IVF-conceived male offspring. After continuous HFD feeding, male offspring in the IVF group underwent earlier and more severe IR. Furthermore, there was a trend of lipid accumulation in the livers of chow-fed IVF offspring. Hepatic steatosis was also more serious in the IVF offspring after HFD treatment. Type 1 receptor (AT1R), which is the primary receptor mediating the action of angiotensin (Ang) II, has been confirmed to be upregulated in IVF offspring livers. Losartan reduced or even eliminated most of the significant differences between the IVF and NC groups after HFD consumption.

CONCLUSIONS

The upregulation of AT1R expression in the liver increased the activity of the local RAS, resulting in abnormal glucose and lipid metabolism and lipid accumulation in the liver, significantly increasing the risk of nonalcoholic fatty liver disease (NAFLD) in IVF offspring.

Hepatic Stellate Cells: Dictating Outcome in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a fast growing, chronic liver disease affecting ∼25% of the global population. Nonalcoholic fatty liver disease severity ranges from the less severe simple hepatic steatosis to the more advanced nonalcoholic steatohepatitis (NASH). The presence of NASH predisposes individuals to liver fibrosis, which can further progress to cirrhosis and hepatocellular carcinoma. This makes hepatic fibrosis an important indicator of clinical outcomes in patients with NASH. Hepatic stellate cell activation dictates fibrosis development during NASH. Here, we discuss recent advances in the analysis of the profibrogenic pathways and mediators of hepatic stellate cell activation and inactivation, which ultimately determine the course of disease in nonalcoholic fatty liver disease/NASH.

(Pro)renin receptor inhibition attenuated liver steatosis, inflammation, and fibrosis in mice with steatohepatitis

The (Pro)renin receptor (PRR) is reportedly involved in hepatic lipid metabolism and hepatocyte PRR knockdown protects mice against hepatosteatosis. However, the impact of PRR inhibition on liver inflammation and fibrosis in nonalcoholic steatohepatitis (NASH) remains unclear. Herein, C57BL/6 mice were fed a normal chow diet or fast food diet (FFD) for 24 weeks. Lentivirus-mediated PRR short hairpin RNA (shRNA) or handle region peptide (HRP), a PRR blocker, was administered for PRR inhibition. Mouse primary hepatocytes were cultured with palmitic acid, prorenin, siRNA-targeted PRR, and HRP. In FFD-fed mice, PRR inhibition via lentivirus-mediated PRR knockdown or HRP significantly attenuated liver steatosis, inflammation, and fibrosis. Mechanistically, PRR knockdown or HRP decreased hepatic acetyl-CoA carboxylase (ACC) abundance and upregulated peroxisome proliferator-activated receptor-alpha (PPARα). HRP treatment also decreased hepatic PRR expression. In addition, intrahepatic oxidative stress, apoptosis and inflammatory cell recruitment were ameliorated by PRR knockdown or HRP treatment, along with suppression of proinflammatory cytokine expression. PRR inhibition downregulated the hepatic expression of profibrotic factors, as well as TGF-β1/SMAD3 pathway. In primary mouse hepatocytes, PRR knockdown with siRNA or HRP downregulated cellular ACC and increased PPARα expression. In conclusion, our findings revealed that PRR inhibition attenuated hepatic steatosis, inflammation, and fibrosis in mice with NASH. Accordingly, targeting PRR signaling may serve as a potential treatment for NASH.

Role of high-salt diet in non-alcoholic fatty liver disease: a mini-review of the evidence

With the rising incidence of both obesity and diabetes, non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide. However, lifestyle intervention remains to be an effective approach for NAFLD due to lack of therapeutic medication. Recently, salt, an essential micronutrient free of calories, has raised a global concern owing to its wide-range healthy relevance. Accumulated evidence has suggested that a long-term high-salt diet (HSD) independently increases the risk of NAFLD. In the past decades, a number of studies have been reported regarding the mechanism of much investigation concerning HSD-induced NAFLD. Here, we review the updates in epidemiology and molecular mechanism of HSD-induced NAFLD and provide a novel insight into the role of HSD in the regulation of lipid metabolism.

Caveolin-1 Alleviates Acetaminophen—Induced Hepatotoxicity in Alcoholic Fatty Liver Disease by Regulating the Ang II/EGFR/ERK Axis

Acetaminophen (APAP) is a widely used antipyretic analgesic which can lead to acute liver failure after overdoses. Chronic alcoholic fatty liver disease (AFLD) appears to enhance the risk and severity of APAP-induced liver injury, and the level of angiotensin II (Ang II) increased sharply at the same time. However, the underlying mechanisms remain unclear. Caveolin-1 (CAV1) has been proven to have a protective effect on AFLD. This study aimed to examine whether CAV1 can protect the APAP-induced hepatotoxicity of AFLD by affecting Ang II or its related targets. In vivo, the AFLD model was established according to the chronic-plus-binge ethanol model. Liver injury and hepatic lipid accumulation level were determined. The levels of Angiotensin converting enzyme 2 (ACE2), Ang II, CAV1, and other relevant proteins were evaluated by western blotting. In vitro, L02 cells were treated with alcohol and oleic acid mixture and APAP. CAV1 and ACE2 expression was downregulated in APAP-treated AFLD mice compared to APAP-treated mice. The overexpression of CAV1 in mice and L02 cells alleviated APAP-induced hepatotoxicity in AFLD and downregulated Ang II, p-EGFR/EGFR and P-ERK/ERK expression. Immunofluorescence experiments revealed interactions between CAV1, Ang II, and EGFR. The application of losartan (an Ang II receptor antagonist) and PD98059 (an ERK1/2 inhibitor) alleviated APAP-induced hepatotoxicity in AFLD. In conclusion, our findings verified that CAV1 alleviates APAP-aggravated hepatotoxicity in AFLD by downregulating the Ang II /EGFR/ERK axis, which could be a novel therapeutic target for its prevention or treatment.

Impact of Maternal Obesity on Liver Disease in the Offspring: A Comprehensive Transcriptomic Analysis and Confirmation of Results in a Murine Model

The global obesity epidemic particularly affects women of reproductive age. Offspring of obese mothers suffer from an increased risk of liver disease but the molecular mechanisms involved remain unknown. We performed an integrative genomic analysis of datasets that investigated the impact of maternal obesity on the hepatic gene expression profile of the offspring in mice. Furthermore, we developed a murine model of maternal obesity and studied the development of liver disease and the gene expression profile of the top dysregulated genes by quantitative real-time polymerase chain reaction (qPCR). Our data are available for interactive exploration on our companion webpage. We identified five publicly available datasets relevant to our research question. Pathways involved in metabolism, the innate immune system, the clotting cascade, and the cell cycle were consistently dysregulated in the offspring of obese mothers. Concerning genes involved in the development of liver disease, Egfr, Vegfb, Wnt2,Pparg and six other genes were dysregulated in multiple independent datasets. In our own model, we observed a higher tendency towards the development of non-alcoholic liver disease (60 vs. 20%) and higher levels of alanine aminotransferase (41.0 vs. 12.5 IU/l, p = 0.008) in female offspring of obese mothers. Male offspring presented higher levels of liver fibrosis (2.4 vs. 0.6% relative surface area, p = 0.045). In a qPCR gene expression analysis of our own samples, we found Fgf21, Pparg, Ppard, and Casp6 to be dysregulated by maternal obesity. Maternal obesity represents a looming threat to the liver health of future generations. Our comprehensive transcriptomic analysis will help to better understand the mechanisms of the development of liver disease in the offspring of obese mothers and can give rise to further explorations.

Detailed Molecular Mechanisms Involved in Drug-Induced Non-Alcoholic Fatty Liver Disease and Non-Alcoholic Steatohepatitis: An Update

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are some of the biggest public health challenges due to their spread and increasing incidence around the world. NAFLD is characterized by intrahepatic lipid deposition, accompanied by dyslipidemia, hypertension, and insulin resistance, leading to more serious complications. Among the various causes, drug administration for the treatment of numerous kinds of diseases, such as antiarrhythmic and antihypertensive drugs, promotes the onset and progression of steatosis, causing drug-induced hepatic steatosis (DIHS). Here, we reviewed in detail the major classes of drugs that cause DIHS and the specific molecular mechanisms involved in these processes. Eight classes of drugs, among the most used for the treatment of common pathologies, were considered. The most diffused mechanism whereby drugs can induce NAFLD/NASH is interfering with mitochondrial activity, inhibiting fatty acid oxidation, but other pathways involved in lipid homeostasis are also affected. PubMed research was performed to obtain significant papers published up to November 2021. The key words included the class of drugs, or the specific compound, combined with steatosis, nonalcoholic steatohepatitis, fibrosis, fatty liver and hepatic lipid deposition. Additional information was found in the citations listed in other papers, when they were not displayed in the original search.

Do renin-angiotensin system inhibitors reduce risk for hepatocellular carcinoma?: A nationwide nested case-control study

BACKGROUND

To date, there has been a renewed interest in renin-angiotensin system inhibitors (RASi) for HCC prevention because they may reduce potent angiogenic factors.

OBJECTIVES

This study set out to investigate associations between RASi use and HCC development.

METHODS

We conducted a nested case-control study. A case was defined as a patient who was newly diagnosed with HCC. We selected 567 cases and controls using 1:1 propensity score matching. RASi exposure was classified into ever-user and never-user, then categorized according to cumulative dose and prescription period. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for HCC incidence according to RASi use were analyzed.

RESULTS

Overall, no significant association was found between exposure to RASi and HCC incidence (ever-user vs. never-user: aOR, 0.77; 95% CI, 0.56-1.07). In subgroup analysis, women receiving RASi ≥30 cumulative defined daily doses (cDDDs) showed significantly lower aORs (0.49; 95% CI, 0.24-0.95. Angiotensin II receptor blockers only-use ≥30 cDDD was significantly associated with reduced risk of HCC (aOR, 0.65; 95% CI, 0.43-0.97). In cases where subjects did not have diabetes mellitus and where the cDDD of RASi was 1800 or more, the risk of HCC development was significantly reduced compared to that in subjects with no RASi exposure (aOR, 0.26; 95% CI, 0.08-0.72).

CONCLUSION

The present study did not verify a significant overall association between RASi use and HCC but indicated lower HCC incidence in some subgroups. The possibility of a beneficial effect at a higher cumulative RASi dose was also presented.

Inhibitory Effect of Valsartan on Pterygium Fibroblasts

PURPOSE

Angiotensin receptor blockers (ARBs) were shown to have antifibrotic properties in ocular and systemic diseases. In this study, our aim was to investigate the effect of an angiotensin receptor blocker, valsartan, on pterygium fibroblasts and compare this effect with that of mitomycin C (MMC).

METHODS

Pterygium tissue samples were obtained from 3 patients during surgical excision. Primary cultured pterygium fibroblasts and L929 cell cultures were treated with different concentrations of MMC and valsartan.

RESULTS

The cell viability decreased with increasing concentrations of valsartan at 48 hours for both cell types. MMC inhibited the proliferation of both cell types at 48 hours. Both agents significantly decreased the cell migration of the 2 cell types, although it was more prominent in the MMC-treated group.

CONCLUSIONS

Valsartan inhibited the proliferation and migration of pterygium fibroblasts. The known favorable safety profile of these drugs and the results of this study showing inhibitory effect on pterygium fibroblasts make valsartan a potential therapeutic agent for pterygium treatment.

Treatments for NAFLD: State of Art

Non-alcoholic fatty liver disease (NAFLD) is to date the most common chronic liver disease in clinical practice and, consequently, a major health problem worldwide. It affects approximately 30% of adults in the general population and up to 70% of patients with type 2 diabetes (T2DM). Despite the current knowledge of the epidemiology, pathogenesis, and natural history of NAFLD, no specific pharmacological therapies are until now approved for this disease and, consequently, general strategies have been proposed to manage it. They include: (a) lifestyle change in order to promote weight loss by diet and physical activity, (b) control of the main cardiometabolic risk factors, (c) correction of all modifiable risk factors leading the development and progression of advanced forms of NAFLD, and (d) prevention of hepatic and extra-hepatic complications. In the last decade, several potential agents have been widely investigated for the treatment of NAFLD and its advanced forms—shedding some light but casting a few shadows. They include some glucose-lowering drugs (such as pioglitazone, glucagon-like peptide-1 (GLP-1) receptor agonists, sodium-glucose co-transporter-2 (SGLT-2) inhibitors), antioxidants (such as vitamin E), statins or other lipid lowering agents, bile and non-bile acid farnesoid X activated receptor (FXR) agonists, and others. This narrative review discusses in detail the different available approaches with the potential to prevent and treat NAFLD and its advanced forms.

Update on New Aspects of the Renin-Angiotensin System in Hepatic Fibrosis and Portal Hypertension: Implications for Novel Therapeutic Options

There is considerable experimental evidence that the renin angiotensin system (RAS) plays a central role in both hepatic fibrogenesis and portal hypertension. Angiotensin converting enzyme (ACE), a key enzyme of the classical RAS, converts angiotensin I (Ang I) to angiotensin II (Ang II), which acts via the Ang II type 1 receptor (AT1R) to stimulate hepatic fibrosis and increase intrahepatic vascular tone and portal pressure. Inhibitors of the classical RAS, drugs which are widely used in clinical practice in patients with hypertension, have been shown to inhibit liver fibrosis in animal models but their efficacy in human liver disease is yet to be tested in adequately powered clinical trials. Small trials in cirrhotic patients have demonstrated that these drugs may lower portal pressure but produce off-target complications such as systemic hypotension and renal failure. More recently, the alternate RAS, comprising its key enzyme, ACE2, the effector peptide angiotensin-(1–7) (Ang-(1–7)) which mediates its effects via the putative receptor Mas (MasR), has also been implicated in the pathogenesis of liver fibrosis and portal hypertension. This system is activated in both preclinical animal models and human chronic liver disease and it is now well established that the alternate RAS counter-regulates many of the deleterious effects of the ACE-dependent classical RAS. Work from our laboratory has demonstrated that liver-specific ACE2 overexpression reduces hepatic fibrosis and liver perfusion pressure without producing off-target effects. In addition, recent studies suggest that the blockers of the receptors of alternate RAS, such as the MasR and Mas related G protein-coupled receptor type-D (MrgD), increase splanchnic vascular resistance in cirrhotic animals, and thus drugs targeting the alternate RAS may be useful in the treatment of portal hypertension. This review outlines the role of the RAS in liver fibrosis and portal hypertension with a special emphasis on the possible new therapeutic approaches targeting the ACE2-driven alternate RAS.

Clinical implications of renin-angiotensin system inhibitors for development and progression of non-alcoholic fatty liver disease

Recently, there has been an increasing interest in the therapeutic efficacy of RAS inhibitors (RASi) in patients with non-alcoholic fatty liver disease (NAFLD) because they may reduce oxidative stress, inflammatory markers, and enhanced fibrosis. An objective of this study was to investigate the role of RASi on NAFLD development and progression in a large cohort. We conducted a nested case-control study. Study subjects were classified into two study cohorts according to baseline NAFLD status: non-NAFLD (n = 184,581) and established NALFD (n = 27,565). An NAFLD development or progression case was defined as a patient with newly developed NAFLD or new progression of advanced fibrosis from non-NAFLD and established NALFD cohorts, respectively. A conditional logistic regression analysis was conducted to estimate the associations between RASi exposure and NAFLD development/progression. Overall, no significant association was evident between RASi use and NAFLD development or progression (NAFLD development; ever-user vs. never-user: OR 1.017; 95% CI 0.842-1.230, NAFLD progression; ever-user vs. never-user: aOR 0.942; 95% CI 0.803-1.105). RASi ever-use in cases of individuals who were obese or who had normal fasting plasma glucose (FPG) was associated with reduced risk of both NAFLD development (body mass index (BMI) ≥ 25 kg/m2: 0.708 [95% confidence interval (CI) 0.535-0.937], FPG of < 100 mg/mL: 0.774 [95% CI 0.606-0.987]) and progression (BMI ≥ 25 kg/m2: 0.668 [95% CI 0.568-0.784], FPG of < 100 mg/mL: 0.732 [95% CI 0.582-0.921]). The present study did not verify a significant overall association between RASi use and NAFLD development/progression but suggested that RASi might prevent NAFLD development and progression among specific subjects.

Role of G Protein-Coupled Receptors in Hepatic Stellate Cells and Approaches to Anti-Fibrotic Treatment of Non-Alcoholic Fatty Liver Disease

The prevalence of non-alcoholic fatty liver disease (NAFLD) is globally increasing. Gaining control over disease-related events in non-alcoholic steatohepatitis (NASH), an advanced form of NAFLD, is currently an unmet medical need. Hepatic fibrosis is a critical prognostic factor in NAFLD/NASH. Therefore, a better understanding of the pathophysiology of hepatic fibrosis and the development of related therapies are of great importance. G protein-coupled receptors (GPCRs) are cell surface receptors that mediate the function of a great variety of extracellular ligands. GPCRs represent major drug targets, as indicated by the fact that about 40% of all drugs currently used in clinical practice mediate their therapeutic effects by acting on GPCRs. Like many other organs, various GPCRs play a role in regulating liver function. It is predicted that more than 50 GPCRs are expressed in the liver. However, our knowledge of how GPCRs regulate liver metabolism and fibrosis in the different cell types of the liver is very limited. In particular, a better understanding of the role of GPCRs in hepatic stellate cells (HSCs), the primary cells that regulate liver fibrosis, may lead to the development of drugs that can improve hepatic fibrosis in NAFLD/NASH. In this review, we describe the functions of multiple GPCRs expressed in HSCs, their roles in liver fibrogenesis, and finally speculate on the development of novel treatments for NAFLD/NASH.

ASK1 Enhances Angiotensin II-Induced Liver Fibrosis In Vitro by Mediating Endoplasmic Reticulum Stress-Dependent Exosomes

Background

Apoptosis signal-regulating kinase 1 (ASK1) has been reported to induce fibrotic signaling in the setting of oxidative stress. However, the role of ASK1 and its mechanism of action in angiotensin II- (Ang II-) induced liver fibrosis remain largely unknown.

Methods

Human hepatic LX-2 stellate cells were treated with Ang II alone or cotreated with Ang II plus an ASK1 inhibitor (GS-4997) or siRNA-targeting ASK1. Immunofluorescent staining, real-time PCR, and western blotting were used to determine the expressionof α-SMA, Col I, and Col III expression. Cell viability was assessed by the CCK-8 assay. The concentrations of IL-1β, IL-18, and TNF-α in conditioned medium were determined by ELISA. The levels of intracellular ROS in LX-2 cells were analyzed using a ROS assay kit. Exosome size was determined by electron microscopy.

Results

Ang II markedly increased the expression of extracellular matrix (ECM) proteins (α-SMA, Col I, and Col III) and proinflammatory cytokines (IL-1β, IL-18, and TNF-α). Ang II also increased the expression of endoplasmic reticulum stress (ERS) markers (GRP78, p-PERK, and CHOP) and p-ASK1. Results also showed that pretreatment with GS-4997 or siRNA could abolish all the abovementioned effects on LX-2 cells. Furthermore, we found that exosome release caused by ASK1-mediated ERS was involved in the activation of LX-2 cells by Ang II. The activation of LX-2 cells could be blocked by treating the exosomes with annexin.

Conclusions

In summary, we found that ASK1 mediates Ang II-activated ERS in HSCs and the subsequent activation of HSCs, suggesting a promising strategy for treating liver fibrosis.

Chymase as a Possible Therapeutic Target for Amelioration of Non-Alcoholic Steatohepatitis

The development and progression of non-alcoholic steatohepatitis (NASH) are linked to oxidative stress, inflammation, and fibrosis of the liver. Chymase, a chymotrypsin-like enzyme produced in mast cells, has various enzymatic actions. These actions include activation of angiotensin II, matrix metalloproteinase (MMP)-9, and transforming growth factor (TGF)-β, which are associated with oxidative stress, inflammation, and fibrosis, respectively. Augmentation of chymase activity in the liver has been reported in various NASH models. Generation of hepatic angiotensin II and related oxidative stress is upregulated in NASH but attenuated by treatment with a chymase inhibitor. Additionally, increases in MMP-9 and accumulation of inflammatory cells are observed in NASH but are decreased by chymase inhibitor administration. TGF-β and collagen I upregulation in NASH is also attenuated by chymase inhibition. These results in experimental NASH models demonstrate that a chymase inhibitor can effectively ameliorate NASH via the reduction of oxidative stress, inflammation, and fibrosis. Thus, chymase may be a therapeutic target for amelioration of NASH.

Angiotensin Receptor 1 Blockers Prolong Time to Recurrence after Radiofrequency Ablation in Hepatocellular Carcinoma patients: A Retrospective Study

Inhibition of angiotensin II synthesis seems to decrease hepatocellular carcinoma recurrence after radical therapies; however, data on the adjuvant role of angiotensin II receptor 1 blockers (sartans) are still lacking. Aim of the study was to evaluate whether sartans delay time to recurrence and prolong overall survival in hepatocellular carcinoma patients after radiofrequency ablation. Data on 215 patients were reviewed. The study population was classified into three groups: 113 (52.5%) patients who received neither angiotensin-converting enzyme inhibitors nor sartans (group 1), 59 (27.4%) patients treated with angiotensin-converting enzyme inhibitors (group 2) and 43 (20.1%) patients treated with sartans (group 3). Survival outcomes were analyzed using Kaplan-Meier analysis and compared with log-rank test. In the whole study population, 85.6% of patients were in Child-Pugh A-class and 89.6% in Barcelona Clinic Liver Cancer A stage. Median maximum tumor diameter was 30 mm (10-40 mm) and alpha-fetoprotein was 25 (1.1-2100) IU/mL. No differences in baseline characteristics among the three groups were reported. Median overall survival was 48 months (42-51) in group 1, 51 months (42-88) in group 2, and 63 months (51-84) in group 3 (p = 0.15). Child-Pugh stage and Model for End-staging Liver Disease (MELD) score resulted as significant predictors of overall survival in multivariate analysis. Median time to recurrence was 33 months (24-35) in group 1, 41 (23-72) in group 2 and 51 months (42-88) in group 3 (p = 0.001). Number of nodules and anti-angiotensin treatment were confirmed as significant predictors of time to recurrence in multivariate analysis. Sartans significantly improved time to recurrence after radiofrequency ablation in hepatocellular carcinoma patients but did not improve overall survival.

A Close Relationship between Non-Alcoholic Fatty Liver Disease Marker and New-Onset Hypertension in Healthy Korean Adults

Background and Objectives

Nonalcoholic fatty liver disease (NAFLD) is an excessive accumulation of fat into the liver as a result of increased inflammation and insulin resistance. Although there can be common pathogenic mechanisms for NAFLD and hypertension associated with the development of cardiovascular diseases, little data are showing the association between NAFLD and hypertension in a large-scale cohort study. Thus, we evaluated the ability of the fatty liver index (FLI), a surrogate marker of NAFLD, to predict the development of hypertension in healthy individuals.

Methods

We included 334,280 healthy individuals without known comorbidities who underwent the National Health check-ups in South Korea from 2009 to 2014. The association between the FLI and hypertension was analyzed using multivariate Cox proportional-hazards models.

Results

During a median of 5.2 years' follow-up, 24,678 subjects (7.4%) had new-onset hypertension. We categorized total subjects into quartile groups according to FLI (range: Q1, 0–4.9; Q2, 5.0–12.5; Q3, 12.6–31.0; and Q4, >31.0). The incidence of hypertension was higher in subjects with the highest FLI than in those with the lowest FLI (Q4, 9,968 [11.9%] vs. Q1, 2,277 [2.7%]; p<0.001). There was a significant correlation between the highest FLI and an increased risk of new-onset hypertension (adjusted hazard ratio between Q4 and Q1, 2.330; 95% confidence interval, 2.218–2.448; p<0.001). FLI was significantly associated with an increased risk of new-onset hypertension regardless of baseline characteristics.

Conclusions

Higher FLI was independently associated with increased risk of hypertension in a healthy Korean population.

Pathways of hepatic and renal damage through non-classical activation of the renin-angiotensin system in chronic liver disease

In liver cirrhosis, renin-angiotensin system (RAS) activation sustains renal sodium retention and hepatic fibrogenesis. New information has recently enlivened the traditional concept of RAS. For instance, renin and prorenin bind their ubiquitous receptors, resulting in the local production of angiotensin (Ang) II; increased serum calcium and calcimimetic agents, through stimulation of extracellular calcium-sensing receptors (CaSR), blunt renin production and lead to natriuretic effects in human and experimental cirrhosis. Alongside systemic production, there is Ang II tissue production within various organs through RAS enzymes different from angiotensin-converting enzyme (ACE), that is chymase, tissue plasminogen activator and several cathepsins. In experimental cirrhosis, inhibition of chymase leads to natriuretic and hepatic antifibrotic effects, without changes in systemic haemodynamics. In the kidney, local RAS coordinates proximal and distal tubular sodium reabsorption. However, renalase, whose plasma and tissue levels are severely altered in experimental cirrhosis, degrades systemic and renal tubule catecholamines, antagonizing the effects of renal RAS. Angiotensinogen-derived natriuretic and vasodilating peptides (Ang1-9, Ang1-7, Ang3-8) and their receptors have been described. Receptor agonists or antagonists are available to affect portal hypertension and sodium retention in cirrhosis. ACE2-dependent generation of Ang1-7 may inhibit experimental liver fibrosis. inhibition of Ang1-7 clearance by means of neprilysin blockade has portal hypotensive and natriuretic effects. Ang1-12, whose production renin does not regulate, is converted to several different angiotensin peptides via chymase. Finally, Ang II behaves as either an antinatriuretic or a natriuretic agent, based on the tissue content of AT₁ R and AT₂ R receptors, their ratio being prone to pharmacological modulation.

Increased Serum Angiotensin II Is a Risk Factor of Nonalcoholic Fatty Liver Disease: A Prospective Pilot Study

Background and Aims

Nonalcoholic fatty liver disease (NAFLD) is one of the most prevalent chronic liver diseases. In this prospective study, we aim to explore the role of angiotensin II (Ang II) and NLRP3 inflammasome in NAFLD patients.

Methods

We prospectively enrolled 96 patients in our hospital from September 2014 to February 2016. Patients were divided into two groups (NAFLD group and Control group), and the serum Ang II level, IL-1β, IL-18, and lipids were analyzed. Correlation and multivariable analyses were used in order to identify the potential risk factors of NAFLD.

Results

Although the two groups share a similar demographic background, the Ang II level of NAFLD group patients was significantly higher than that of the Control group (42.18 ± 12.37 vs. 36.69 ± 13.90, p = 0.014) when abdominal ultrasound was used for grouping. This finding was confirmed when a FibroScan Cap value was selected to divide participants into the NAFLD group and Control group (41.16 ± 13.06 vs. 34.85 ± 12.64, p = 0.040). Multivariable analysis showed that Ang II level is an independent risk factor of NAFLD whether abdominal ultrasound (OR = 1.056, p = 0.037) or FibroScan Cap value (OR = 1.069, p = 0.013) was deemed as the diagnostic standard. Furthermore, stepwise regression analysis was carried out between Ang II with other parameters and we discovered that Ang II had a linear correlation with IL-1β.

Conclusion

Ang II levels of NAFLD patients significantly increased, and elevated Ang II level is an independent risk factor of NAFLD. Our preliminary results also indicate that Ang II may promote the development of NAFLD by activating NLRP3 inflammasome.

Pharmacologic therapy for nonalcoholic steatohepatitis focusing on pathophysiology

The paradigm of chronic liver diseases has been shifting. Although hepatitis B and C viral infections are still the main causes of liver cirrhosis and hepatocellular carcinoma (HCC), the introduction of effective antiviral drugs may control or cure them in the near future. In contrast, the burden of nonalcoholic fatty liver disease (NAFLD) has been increasing for decades, and 25 to 30% of the general population in Korea is estimated to have NAFLD. Over 10% of NAFLD patients may have nonalcoholic steatohepatitis (NASH), a severe form of NAFLD. NASH can progress to cirrhosis and HCC. NASH is currently the second leading cause to be placed on the liver transplantation list in the United States. NAFLD is associated with obesity, type 2 diabetes, dyslipidemia, and metabolic syndrome. The pathophysiology is complex and associated with lipotoxicity, inflammatory cytokines, apoptosis, and insulin resistance. The only proven effective treatment is weight reduction by diet and exercise. However, this may not be effective for advanced fibrosis or cirrhosis. Therefore, effective drugs are urgently needed for treating these conditions. Unfortunately, no drugs have been approved for the treatment of NASH. Many pharmaceutical companies are trying to develop new drugs for the treatment of NASH. Some of them are in phase 2 or 3 clinical trials. Here, pharmacologic therapies in clinical trials, as well as the basic principles of drug therapy, will be reviewed, focusing on pathophysiology.

Quantitative Proteomic Analysis Reveals the Deregulation of Nicotinamide Adenine Dinucleotide Metabolism and CD38 in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) has become a major health challenge worldwide. However, the precise etiological and pathophysiological factors involved in IBD remain unclear. Proteomics can be used for large-scale protein identification analysis. In the current study, using tandem mass tag- (TMT-) based shotgun proteomics, proteomic differences between intestinal tissue from health controls, patients with Crohn's disease (CD), and patients with ulcerative colitis (UC) were compared. Proteins with fold change >2 or <0.5 and P value < 0.05 between groups were considered differentially expressed. ProteinAtlas was used to analyze the tissue specificity of differentially expressed proteins (DEPs). Reactome pathway analysis was applied to cluster functional pathways. A total of 4786 proteins were identified, with 59 proteins showing higher levels and 43 showing lower levels in patients with IBD than in controls. Seventeen proteins, including angiotensin converting enzyme 2 (ACE2) and angiotensin converting enzyme 1 (ACE), showed higher levels in CD than in UC. Several novel proteins such as CD38, chitinase 3-like 1 (CHI3L1), olfactomedin 4 (OLFM4), and intelectin 1 were screened out between patients with IBD and controls. When proteins with fold change >1.2 or <0.84 and P value < 0.05 between groups were considered differentially expressed, the expression of 10 proteins, including CD38, involved in the nicotinamide adenine dinucleotide (NAD) metabolism and signaling pathway showed significant changes in IBD. Using the NCBI GEO database, we confirmed increased CD38 mRNA expression in patients with UC and in mouse colitis models. Protein CD38 expression was higher in CD and UC than in normal controls. CD38 expression was higher in inflamed tissues than in noninflamed tissues, and CD38 was located in F4/80-positive cells. Our study may provide novel insights into the molecular pathogenesis of IBD. Further studies are required on the role of NAD metabolism and CD38 in intestinal inflammation.

High Fib4 index in patients with suspected NASH is associated with elevation of chymase-dependent angiotensin II-forming activity in circulating mononuclear leucocytes

Fatal hepatic disease is closely related to non-alcoholic fatty liver disease, especially non-alcoholic steatohepatitis (NASH). NASH is associated with cardiovascular events because it develops on the background of lifestyle-related diseases. Chymase-dependent angiotensin II-forming activity (dAIIFA) in circulating mononuclear leucocytes (CML) is a marker of local angiotensin II production and inflammation. This study investigated the association between CML chymase dAIIFA and NASH. Cardiovascular outpatients were recruited and the Fib4 index (F4I) was calculated. Patients with an F4I > 2.67 were classified into the high F4I group and these patients were strongly suspected to have NASH, while patients with an F4I < 1.30 were classified into the low F4I group. Patient background factors were compared between these groups. CML chymase dAIIFA was measured by ELISA using Nma/Dnp-modified angiotensin I. Among 499 patients, 16% were classified into the high F4I group. Compared with the low F4I group, the high F4I group had a significantly higher age, pancytopenia, more frequent diabetes mellitus, lower diastolic blood pressure, lower estimated glomerular filtration rate, higher brain natriuretic peptide, lower plasma aldosterone concentration, higher total AIIFA, higher CML chymase dAIIFA, and higher pulse wave velocity. Contrary to expectations, the body mass index, triglycerides, and low-density lipoprotein cholesterol were relatively low in the high F4I group. Many cardiovascular outpatients have a high F4I and can probably be categorized as NASH. The high F4I patients had few features of metabolic syndrome and were suspected to have elevated tissue chymase dAIIFA contributing to inflammation in the liver as well as in cardiovascular organs.

Managing diabetes and liver disease association

There is strong association between liver diseases and diabetes (DM) which is higher than expected by a chance association of two very common disorders. It can be classified into three categories: Liver disease related to diabetes, hepatogenous diabetes (HD), and liver disease occurring coincidentally with DM. The criteria for the diagnosis of diabetes associating liver disease are the same for primary diabetes. Two hours post glucose load is a better screening test for HD. HbA1c may not be suitable for diagnosis or monitoring of diabetes associating advanced liver disease. Apart from the increased cardiovascular risk in patients with type 2 DM (T2 DM) and NAFLD, the cardiovascular and retinopathy risk is low in HD. Patients with metabolic derangement should be screened for NAFLD which in turn may predict T2 DM development. Similarly, patients with established T2 DM should also be screened for NAFLD which further contributes to diabetes worsening. Diabetes is a significant risk factor for progression of the chronic liver disease. It is associated with poor patient survival. Treatment of diabetes associating liver disease appears beneficial. Metformin, if tolerated and not contraindicated, is recommended as a first-line therapy for patients with diabetes and chronic liver disease (CLD). If the hepatic disease is severe, insulin secretagogues should be avoided because of the increased risk of hypoglycaemia. Pioglitazone may be useful in patients with fatty liver disease. DPP-4 inhibitors showed effectiveness and safety for the treatment of T2 DM in CLD patients up to those with child B stage. GLP-1 receptor agonists and SGLT-2 inhibitors exhibit positive effects on weight and are associated with minimal risk of hypoglycaemia. Insulin must be used with caution, as hypoglycaemia may be a problem. Insulin analogues are preferred in the context of hypoglycaemia Statins can be used to treat dyslipidaemia in NAFLD, also the use of angiotensin II receptor antagonist for hypertension is safe and beneficial Given the clear association between diabetes mellitus and hepatocellular carcinoma, the strict control of glycaemia with insulin sensitizers can be essential in its prevention. The addition of DM to the currently used scores (Child-Pugh and MELD scores) may enhance the sensitivity and the specificity for prediction of morbidity and mortality rates in cirrhotic patients. In the new era of directly acting antiviral agents (DAAs) for HCV treatment, it is recommended to follow up lipid profile and blood sugar levels following SVR in order to adjust doses of medications used in diabetic (SVR is associated with reduction in insulin requirements) and dyslipidaemic patients (rebound increase in the lipid profile after clearing the virus may increase risk of cardiovascular disease (CVD)). The issues of post liver transplant diabetes and relation between DM and chronic HBV are highlighted. This narrative review and Consensus-based practice guidance (under revision and criticism) are based on a formal review and analysis of the recently published world literature on the topic (Medline search up to September 2017); and the experience of the authors and independent reviewers.

Acyclic retinoid and angiotensin-II receptor blocker exert a combined protective effect against diethylnitrosamine-induced hepatocarcinogenesis in diabetic OLETF rats

Background

Insulin resistance (IR) is closely associated with the progression of hepatocellular carcinoma (HCC). Acyclic retinoid (ACR) targets retinoid X receptor α and reportedly prevents HCC recurrence in clinical practice. Angiotensin-II receptor blocker (ARB) can also inhibit experimental hepatocarcinogenesis and HCC development. These are reported to suppress IR-based hepatocarcinogenesis; however, limited data are available regarding the combined effects of both these agents. This study aimed to investigate the combined chemopreventive effect of ACR and ARB on liver tumorigenesis on rats with congenital diabetes.

Methods

Male diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) and non-diabetic Long-Evans Tokushima Otsuka (LETO) rats underwent 70% partial hepatectomy following a single intraperitoneal injection of diethylnitrosamine to induce hepatocarcinogenesis and the administration of ACR (peretinoin, 40 mg/kg/day), ARB (losartan, 30 mg/kg/day), and a combination of ACR and ARB. Six weeks thereafter, we assessed the size and number of the pre-neoplastic lesions (PNL) as well as the altered angiogenesis, oxidative stress, and chronic inflammation in the liver. Moreover, we assessed the effects exerted by ACR and ARB on in vitro cell growth in human HCC cell lines and human umbilical vascular endothelial cells (HUVECs).

Results

OLETF rats showed increase in the size and number of PNLs compared to LETO rats. ACR suppressed the augmentation in size and number of PNLs in the OLETF rats with suppression of cell growth, intrahepatic angiogenesis, lipid peroxidation, oxidative DNA damage, and proinflammatory cytokine production. Combining ACR with ARB enhanced the tumor-suppressive effect and ameliorated intrahepatic angiogenesis, lipid peroxidation, and proinflammatory status; however, cell growth and oxidative DNA damage remained unchanged. IR-mimetic condition accelerated in vitro proliferative activity in human HCC cells, while ACR inhibited this proliferation with G0/G1 arrest and apoptosis. Furthermore, ACR and ARB significantly attenuated the HUVECs proliferation and tubular formation under the IR-mimetic condition, and a combination of both agents demonstrated greater inhibitory effects on HUVEC growth than each single treatment.

Conclusions

ACR and ARB exert a combined inhibitory effect against IR-based hepatocarcinogenesis by the inhibition of cell growth, intrahepatic angiogenesis, and oxidative stress. Thus, this combination therapy appears to hold potential as a chemopreventive treatment therapy against HCC.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5099-6) contains supplementary material, which is available to authorized users.

Future Pharmacotherapy for Non-alcoholic Steatohepatitis (NASH): Review of Phase 2 and 3 Trials

Non-alcoholic steatohepatitis (NASH) results from inflammation and hepatocyte injury in the setting of hepatic steatosis. Non-alcoholic steatohepatitis increases the risk of progression to liver fibrosis and cirrhosis, and is the most rapidly growing etiology for liver failure and indication for liver transplantation in the USA. Weight loss and lifestyle modification remain the standard first-line treatment, as no USA Food and Drug Administration-approved pharmacotherapy currently exists. The past decade has seen an explosion of interest in drug development targeting pathologic pathways in non-alcoholic steatohepatitis, with numerous phase 2 and 3 trials currently in progress. Here, we concisely review the major targets and mechanisms of action by class, summarize results from completed pivotal phase 2 studies, and provide a detailed outline of key active studies with trial data for drugs in development, including obeticholic acid, elafibranor, cenicriviroc and selonsertib.

Non-alcoholic fatty liver disease and hypertension: coprevalent or correlated?

OBJECTIVE

To provide a comprehensive review summarizing the existing evidence on the association between nonalcoholic fatty liver disease (NAFLD) and hypertension (HT) independent of other components of metabolic syndrome.

METHODS

We searched the literature through Medline and the Cochrane Library for studies evaluating the relationship between hypertension and fatty liver disease.

RESULTS

Studies testing this association are limited, but agree that HT and fatty liver disease are inter-related independent of other components of the metabolic syndrome such as obesity and diabetes mellitus. Clinical evidence shows that NAFLD is associated with new-onset HT, whereas increased blood pressure is related to the development of fatty liver disease and the possible subsequent progression to liver fibrosis. Insulin resistance and activation of the renin-angiotensin-aldosterone system (RAAS) might provide potential pathophysiologic links between these clinical entities. Until further evidence is available, patients with HT should be meticulously evaluated and treated for fatty liver disease and vice versa. RAAS inhibitors have been tested in NAFLD, presenting a favorable profile by decreasing insulin resistance and fibrosis progression.

CONCLUSION

NAFLD and HT are associated independent of traditional cardiovascular risk factors. Insulin resistance appears to be the main linking mechanism. Although RAAS inhibitors are the most beneficial treatment option for HT in patients with NAFLD, randomized studies on the administration of these agents in HT patients with NAFDL are warranted to provide optimal treatment options in these high cardiovascular risk individuals.

Risk of cardiomyopathy and cardiac arrhythmias in patients with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a common, progressive liver disease that affects up to one-quarter of the adult population worldwide. The clinical and economic burden of NAFLD is mainly due to liver-related morbidity and mortality (nonalcoholic steatohepatitis, cirrhosis or hepatocellular carcinoma) and an increased risk of developing fatal and nonfatal cardiovascular disease, chronic kidney disease and certain types of extrahepatic cancers (for example, colorectal cancer and breast cancer). Additionally, there is now accumulating evidence that NAFLD adversely affects not only the coronary arteries (promoting accelerated coronary atherosclerosis) but also all other anatomical structures of the heart, conferring an increased risk of cardiomyopathy (mainly left ventricular diastolic dysfunction and hypertrophy, leading to the development of congestive heart failure), cardiac valvular calcification (mainly aortic-valve sclerosis), cardiac arrhythmias (mainly atrial fibrillation) and some cardiac conduction defects. This Review focuses on the association between NAFLD and non-ischaemia-related cardiac disease, discusses the putative pathophysiological mechanisms and briefly summarizes current treatment options for NAFLD that might also beneficially affect cardiac disease.

Evaluation of postprandial hypoglycemia in patients with nonalcoholic fatty liver disease by oral glucose tolerance testing and continuous glucose monitoring

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD) is often associated with insulin resistance and glucose intolerance. Postprandial hypoglycemia frequently occurs in NAFLD patients; however, the details remain unclear.

PATIENTS AND METHODS

The 75-g oral glucose tolerance test (75gOGTT) in 502 patients with biopsy-proven NAFLD and continuous glucose monitoring (CGM) in 20 patients were performed, and the characteristics and causes of postprandial hypoglycemia were investigated.

RESULTS

The proportion of patients in the Hypo subgroup [plasma glucose (PG) at 180 min<fasting-PG (FPG)] among patients with normal glucose tolerance was significantly higher than that with diabetes mellitus and impaired glucose tolerance or impaired fasting glucose. FPG and hemoglobin A1c (HbA1c) were lower, and area under the curve of total insulin secretion within 120 min (<120 min) was higher in Hypo than Hyper in overall patients. Although FPG and PG at 30 min were higher in Hypo than Hyper, HOMA-IR and the insulinogenic index were not different in normal glucose tolerance and impaired glucose tolerance or impaired fasting glucose. In multivariate logistic regression analysis, low HbA1c, low fasting immunoreactive insulin, and high area under the curve of total insulin secretion (<120 min) were found to be independent factors associated with hypoglycemia. CGM showed postprandial hypoglycemia until lunch in 70% of NAFLD patients. However, no remarkable relationship in terms of hypoglycemia was identified between the 75gOGTT and CGM.

CONCLUSION

Postprandial hypoglycemia was identified in many NAFLD patients detected by 75gOGTT and CGM. It was clarified that important causes of postprandial hypoglycemia were related to low HbA1c, an early elevation of PG, low fasting and relatively low early insulin secretion, and delayed hyperinsulinemia.

The role of the angiotensin II type I receptor blocker telmisartan in the treatment of non-alcoholic fatty liver disease: a brief review

Non-alcoholic fatty liver disease (NAFLD) is currently considered an important component of metabolic syndrome (MetS). The spectrum of NAFLD includes conditions that range from simple hepatic steatosis to non-alcoholic steatohepatitis. NAFLD is correlated with liver-related death and is predicted to be the most frequent indication for liver transplantation by 2030. Insulin resistance is directly correlated to the central mechanisms of hepatic steatosis in NAFLD patients, which is strongly correlated to the imbalance of the renin–angiotensin system, that is involved in lipid and glucose metabolism. Among the emerging treatment approaches for NAFLD is the anti-hypertensive agent telmisartan, which has positive effects on liver, lipid, and glucose metabolism, especially through its action on the renin–angiotensin system, by blocking the ACE/AngII/AT1 axis and increasing ACE2/Ang(1–7)/Mas axis activation. However, treatment with this drug is only recommended for patients with an established indication for anti-hypertensive therapy. Thus, there is an increased need for large randomized controlled trials with the aim of elucidating the effects of telmisartan on liver disease, especially NAFLD. From this perspective, the present review aims to provide a brief examination of the pathogenesis of NAFLD/NASH and the role of telmisartan on preventing liver disorders and thus to improve the discussion on potential therapies.

Chymase Inhibitor as a Novel Therapeutic Agent for Non-alcoholic Steatohepatitis

Non-alcoholic steatohepatitis (NASH) is characterized by inflammation and fibrosis, in addition to steatosis, of the liver, but no therapeutic agents have yet been established. The mast cell protease chymase can generate angiotensin II, matrix metalloproteinase-9 and transforming growth factor-β, all of which are associated with liver inflammation or fibrosis. In animal models of NASH, augmented chymase has been observed in the liver. In histological analysis, chymase inhibitor prevented hepatic steatosis, inflammation, and fibrosis. Chymase inhibitor also attenuated the augmentation of angiotensin II, matrix metalloproteinase-9, and transforming growth factor-β observed in the liver of NASH. Oxidative stress, inflammatory markers, and collagen were attenuated by chymase inhibition. Moreover, chymase inhibitor showed a mitigating effect on established NASH, and survival rates were significantly increased by treatment with chymase inhibitor. In this review, we propose that chymase inhibitor has potential as a novel therapy for NASH.

Renin-angiotensin system inhibition ameliorates CCl4-induced liver fibrosis in mice through the inactivation of nuclear transcription factor kappa B

Therapeutic interventions for liver fibrosis are still limited due to the complicated molecular pathogenesis. Renin-angiotensin system (RAS) seems to contribute to the development of hepatic fibrosis. Therefore, we aimed to examine the effect of RAS inhibition on CCl₄-induced liver fibrosis. Mice were treated with silymarin (30 mg·kg^-1), perindopril (1 mg·kg^-1), fosinopril (2 mg·kg^-1), or losartan (10 mg·kg^-1). The administration of RAS inhibitors improved liver histology and decreased protein expression of alpha smooth muscle actin (α-SMA) and hepatic content of hydroxyproline. These effects found to be mediated via inactivation of nuclear transcription factor kappa B (NFκB) pathway by the inhibition of NFκB p65 phosphorylation at the Ser536 residue and phosphorylation-induced degradation of nuclear factor kappa-B inhibitor alpha (NFκBia) subsequently inhibited NFκB-induced TNF-α and TGF-β1, leading to lower levels of tissue inhibitor of metalloproteinase-1 (TIMP-1) and vascular endothelial growth factor (VEGF). We concluded that the tissue affinity of the angiotensin converting enzyme inhibitors (ACEIs) has no impact on its antifibrotic activity and that interfering the RAS either through the inhibition of ACE or the blockade of AT1R has the same therapeutic benefit. These results suggest RAS inhibitors as promising candidates for further clinical trials in the management of hepatic fibrosis.

Clinical application of angiotensin receptor blockers in patients with non-alcoholic fatty liver disease: a systematic review and meta-analysis

Objective

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases, ranging from simple steatosis to progressive steatohepatitis and cirrhosis. Because of their anti-inflammatory and anti-fibrotic effects, angiotensin receptor blockers (ARBs) are potential therapeutic agents for NAFLD. The present systematic review assessed the effectiveness of ARBs in NAFLD management.

Results

Accounting for data overlap and exclusion criteria, randomized controlled trial -based and single-arm meta-analyses were conducted for four studies with 362 patients and eight studies with 525 patients, respectively. Although alanine aminotransferase levels were not significantly affected by ARB treatment (standardized mean difference 0.20; 95% confidence interval (CI) [−0.04, 0.44]; P = 0.10), a fixed-effect model revealed a decreasing trend in alanine transaminase levels. Low-density lipoprotein levels were reduced by ARB treatment (MD 5.21; 95% CI [3.01, 7.40]; P < 0.00001), and total cholesterol also decreased in response to ARBs (MD 2.10; 95% CI [−0.37, 4.57]; P = 0.10). However, the fibrosis score and NAFLD activity score were not significantly improved by ARB treatment (MD 0.10; 95% CI [−0.58, 0.78]; P = 0.77) (MD −0.25; 95% CI [−1.05, 0.55]; P = 0.53).

Materials and Methods

Keywords were used to identify studies in PubMed, EMBASE, CENTRAL, Web of Science and CNKI published up to July 31, 2017. Single-arm and RCT-based meta-analyses of the available data were performed using RevMan (version 5.3).

Conclusions

Although ARBs significantly decreased plasma low-density lipoprotein and total cholesterol levels, the current evidence is insufficient to support the efficacy of ARBs in managing fibrosis in NAFLD patients.

Differences in characteristics of glucose intolerance between patients with NAFLD and chronic hepatitis C as determined by CGMS

Glucose intolerance frequently develops in accordance with the progression of chronic liver disease. However, differences in the characteristics of glucose intolerance between patients with nonalcoholic fatty liver disease (NAFLD) and those with chronic hepatitis C (C-CH) remain incompletely understood. To clarify these differences, patients with NAFLD (n = 37) and C-CH (n = 40) were evaluated with a continuous glucose monitoring system (CGMS). In the patients with NAFLD, Maximum blood glucose concentration and blood glucose swings were significantly correlated with hepatic fibrosis markers. In the patients with C-CH, however, those two CGMS parameters were negatively correlated with the serum albumin (ALB) concentration. Furthermore, in the patients with C-CH with an ALB concentration of ≤4.0 g/dl, those two CGMS parameters were negatively correlated with the ALB concentration with greater statistical significance. In conclusion, obvious differences in the characteristics of glucose intolerance between patients with NAFLD and those with C-CH were clarified. In patients with NAFLD, glucose intolerance gradually progressed in accordance with the progression of hepatic fibrosis. In those with C-CH, glucose intolerance suddenly developed upon the appearance of hypoalbuminaemia.

BML-111 equilibrated ACE-AngII-AT1R and ACE2-Ang-(1-7)-Mas axis to protect hepatic fibrosis in rats

BACKGROUND

It was recently reported Lipoxins (LXs) had protective effects on fibrous diseases, and renin-angiotensin-aldosterone system (RAAS) had played vital and bidirectional roles in hepatic fibrosis. In this paper, a hepatic fibrosis model, induced by carbon tetrachloride (CCL₄) in rats, was used to observe the relations between RAAS and LXs, as well as to further explore the alternative anti-fibrosis mechanisms of LXs.

METHODS

The model was evaluated by morphological observations and biochemical assays. The activities and contents of angiotensin converting enzyme (ACE) and angiotensin converting enzyme 2 (ACE2) were examined through assay kits and ELISA. The expression levels of angiotensinII (AngII), Angiotensin II type 1 receptor (AT1R), angiotensin-(1-7) (Ang-1-7), and Mas were all measured using real time PCR, ELISA, and Western blot.

RESULTS

The model was established successfully and BML-111 significantly ameliorated CCL₄-induced hepatic fibrosis, including reduction inflammation injury, decrease extracellular matrix deposition, and improvement hepatic functions. Furthermore, BML-111 could obviously decrease not only the activities of ACE but also the expression levels of ACE, AngII,and AT1R, which were induced by CCL₄. On the other hand, BML-111 could markedly increase the activities of ACE2, besides the expression levels of ACE2, Ang-(1-7) and Mas. More importantly, BOC-2, a lipoxin A₄ receptor blocker, could reverse all these phenomena.

CONCLUSIONS

Equilibrating ACE-AngII-AT1R axis and ACE2-Ang-(1-7)-Mas axis mediated the protective effect of BML-111 on hepatic fibrosis in rats.

The fatty liver index as a predictor of incident chronic kidney disease in a 10-year prospective cohort study

Background

Although non-alcoholic fatty liver disease (NAFLD) is considered to be associated with chronic kidney disease (CKD), long-term follow up data is lacking. We investigated whether NAFLD, as determined by the fatty liver index (FLI), could predict incident CKD in 10-year prospective cohort study. We also assessed the clinical utility of FLI to predict the development of CKD.

Methods

6,238 adults aged 40 to 69 years without baseline CKD from the Ansan—Ansung cohort were examined. Patients were classified according to FLI as follows: FLI<30, no NAFLD; FLI≥60, NAFLD; and 30≤ FLI<60, intermediate. Incident CKD was defined as estimated glomerular filtration rate (eGFR) <60 ml/min per 1.73 m². The clinical utility of FLI in predicting incident CKD was estimated via area under the receiver-operating characteristic curve (AUC), net reclassification improvement (NRI), and integrated discrimination improvement (IDI) analyses.

Results

During an average of 10 years of follow-up, 724 subjects (15.21%) developed CKD. The adjusted hazard ratio [95% confidence interval (CI)] for incident CKD increased in a graded manner with FLI increased (<30 vs. 30–59 vs. ≥60 = 1 vs. 1.17 [0.997–1.375] vs. 1.459 [1.189–1.791], respectively, P for trend = 0.0012). Incorporation of FLI into traditional risk factors of CKD significantly increased prediction of incident CKD based on NRI (17%; 95% CI, 8.9–25%; P-value <0.001) and IDI (0.002; 95% CI, 0.0046–0.0143; P-value = 0.046).

Conclusions

FLI, a surrogate marker of NAFLD, was an independent risk factor for incident CKD. FLI provides meaningful incremental risk reclassification beyond that of conventional risk factors of CKD.

Pharmacological evaluation of pioglitazone and candesartan cilexetil in a novel mouse model of non-alcoholic steatohepatitis, modified choline-deficient, amino acid-defined diet fed low-density lipoprotein receptor knockout mice

AIM

Low-density lipoprotein receptor knockout (LDLR-KO) mice fed a modified choline-deficient and amino acid-defined (mCDAA) diet show non-alcoholic steatohepatitis (NASH)-like pathophysiology. In order to pharmacologically benchmark this model, effects of pioglitazone (a thiazolidinedione) and candesartan cilexetil (an angiotensin II type 1 receptor blocker) on steatosis and liver fibrosis were examined.

METHODS

Pioglitazone (10 mg/kg) and candesartan cilexetil (3 mg/kg) were given orally once daily to LDLR-KO mice under mCDAA diet for 7 weeks. Blood biochemistry and hepatic histology were assessed, and hepatic gene expression levels and triglyceride content were measured.

RESULTS

Pioglitazone suppressed hepatic COL1A1 gene expression by 43% and attenuated hepatic fibrosis areas by 49%. Pioglitazone also decreased plasma alanine aminotransferase levels, liver weight, hepatic triglyceride content, and hepatic expression of other fibrosis-related genes such as TGFB1, SPP1, TIMP1, and IL6. Candesartan cilexetil suppressed hepatic COL1A1 gene expression by 33%, whereas the other end-points including hepatic fibrosis areas were not affected.

CONCLUSIONS

Pioglitazone showed anti-fibrotic effects accompanied by improving hepatic transaminase activity and hepatic lipid accumulation, but the effect of candesartan cilexetil was only limited, unlike previous reports for angiotensin II type 1 receptor blockers. As the pharmacological effects of pioglitazone in the current animal model are similar to those reported in patients with NASH, this model may represent some aspects of the pathophysiology of NASH. Further profiling using other agents or mechanisms that have been tested in the clinic will better clarify the utility of the animal model.

A randomised controlled trial of losartan as an anti-fibrotic agent in non-alcoholic steatohepatitis

Introduction

Non-alcoholic fatty liver disease (NAFLD) is a common liver disease worldwide. Experimental and small clinical trials have demonstrated that angiotensin II blockers (ARB) may be anti-fibrotic in the liver. The aim of this randomised controlled trial was to assess whether treatment with Losartan for 96 weeks slowed, halted or reversed the progression of fibrosis in patients with non-alcoholic steatohepatitis (NASH).

Methods

Double-blind randomised-controlled trial of Losartan 50 mg once a day versus placebo for 96 weeks in patients with histological evidence of NASH. The primary outcome for the study was change in histological fibrosis stage from pre-treatment to end-of-treatment.

Results

The study planned to recruit 214 patients. However, recruitment was slower than expected, and after 45 patients were randomised (median age 55; 56% male; 60% diabetic; median fibrosis stage 2), enrolment was suspended. Thirty-two patients (15 losartan and 17 placebo) completed follow up period: one patient (6.7%) treated with losartan and 4 patients (23.5%) in the placebo group were “responders” (lower fibrosis stage at follow up compared with baseline). The major reason for slow recruitment was that 39% of potentially eligible patients were already taking an ARB or angiotensin converting enzyme inhibitor (ACEI), and 15% were taking other prohibited medications.

Conclusions

Due to the widespread use of ACEI and ARB in patients with NASH this trial failed to recruit sufficient patients to determine whether losartan has anti-fibrotic effects in the liver.

Trial registration

ISRCTN 57849521

Hepatic structural enhancement and insulin resistance amelioration due to AT1 receptor blockade

Over the last decade, the role of renin-angiotensin system (RAS) on the development of obesity and its comorbidities has been extensively addressed. Both circulating and local RAS components are up-regulated in obesity and involved in non-alcoholic fatty liver disease onset. Pharmacological manipulations of RAS are viable strategies to tackle metabolic impairments caused by the excessive body fat mass. Renin inhibitors rescue insulin resistance, but do not have marked effects on hepatic steatosis. However, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers (ARB) yield beneficial hepatic remodeling. ARBs elicit body mass loss and normalize insulin levels, tackling insulin resistance. Also, this drug class increases adiponectin levels, besides countering interleukin-6, tumoral necrosis factor-alpha, and transforming growth factor-beta 1. The latter is essential to prevent from liver fibrosis. When conjugated with peroxisome proliferator-activated receptor (PPAR)-alpha activation, ARB fully rescues fatty liver. These effects might be orchestrated by an indirect up-regulation of MAS receptor due to angiotensin II receptor type 1 (AT1R) blockade. These associations of ARB with PPAR activation and ACE2-angiotensin (ANG) (1-7)-MAS receptor axis deserve a better understanding. This editorial provides a brief overview of the current knowledge regarding AT1R blockade effects on sensitivity to insulin and hepatic structural alterations as well as the intersections of AT1R blockade with peroxisome proliferator-activated receptor activation and ACE2-ANG (1-7) - MAS receptor axis.

Incidence and Predictors of Advanced Liver Fibrosis by a Validated Serum Biomarker in Liver Transplant Recipients

Background and Aims. Serum fibrosis biomarkers have shown good accuracy in the liver transplant (LT) population. We employed a simple serum biomarker to elucidate incidence and predictors of advanced fibrosis after LT over a long follow-up period. Methods. We included 440 consecutive patients who underwent LT between 1991 and 2013. Advanced liver fibrosis was defined as FIB-4 > 3.25 beyond 12 months after LT. Results. Over 2030.5 person-years (PY) of follow-up, 189 (43%) developed FIB-4 > 3.25, accounting for an incidence of 9.3/100 PY (95% confidence interval [CI], 8.1-10.7). Advanced fibrosis was predicted by chronic HCV infection (adjusted hazard ratio (aHR) = 3.96, 95% CI 2.92-5.36, p < 0.001), hypoalbuminemia (aHR = 2.31, 95% CI 1.72-3.09; p < 0.001), and hyponatremia (aHR = 1.48, 95% CI 1.09-2.01; p = 0.01). LT recipients with more than 1 predictor had a higher incidence of advanced fibrosis, the highest being when all 3 predictors coexisted (log-rank: p < 0.001). Conclusions. Chronic HCV infection, hypoalbuminemia, and hyponatremia predict progression to advanced liver fibrosis following LT. Patients with these risk factors should be serially monitored using noninvasive fibrosis biomarkers and prioritized for interventions.

Aliskiren effect on non-alcoholic steatohepatitis in metabolic syndrome

BACKGROUND

Non-alcoholic steatohepatitis (NASH) is highly associated with metabolic syndrome, a major cause of morbidity in the globalized society. The renin-angiotensin system (RAS) influences hepatic fatty acid metabolism, inflammation and fibrosis. Thus, in the present study, we aimed to evaluate the effect of aliskiren, a direct renin inhibitor, on metabolic syndrome-related NASH.

METHODS

C57BL/6 male mice (n = 45) were divided into three groups: controls; animals inoculated with streptozotocin (STZ) (40 mg/kg/day) for 5 days and fed with high fat diet (HFD) for 8 weeks; and animals inoculated with STZ for 5 days, fed with HFD for 8 weeks and treated with aliskiren (100 mg/kg/day) for the final 2 weeks. Glycemic and insulin levels, hepatic lipid profile, histological parameters and inflammatory protein expression were analyzed.

RESULTS

Aliskiren normalized plasma glucose and insulin levels, reduced cholesterol, triglycerides and total fat accumulation in liver and diminished hepatic injury, steatosis and fibrosis. These results could be explained by the ability of aliskiren to block angiotensin-II, lowering oxidative stress and inflammation in liver. Also, it exhibited a beneficial effect in increasing insulin sensitivity.

CONCLUSION

These findings support the use of aliskiren in the treatment of metabolic syndrome underlying conditions. However, clinical studies are indispensable to test its effectiveness in the treatment of patients with metabolic syndrome.