Effect of exenatide therapy on hepatic fat quantity and hepatic biomarkers in type 2 diabetic patients

Hepatic insulin receptor: new views on the mechanisms of liver disease

Over 65 % of people with obesity display the metabolic-associated fatty liver disease (MAFLD), which can manifest as steatohepatitis, fibrosis, cirrhosis, or liver cancer. The development and progression of MAFLD involve hepatic insulin resistance and reduced insulin clearance. This review discusses the relationships between altered insulin signaling, hepatic insulin resistance, and reduced insulin clearance in the development of MAFLD and how this provides the impetus for exploring the use of insulin sensitizers to curb this disease. The review also explores the role of the insulin receptor in hepatocytes and hepatic stellate cells and how it signals in metabolic and end-stage liver diseases. Finally, we discuss new research findings that indicate that advanced hepatic diseases may be an insulin-sensitive state in the liver and deliberate whether insulin sensitizers should be used to manage late-stage liver diseases.

GLP-1 Receptor Agonists in Non-Alcoholic Fatty Liver Disease: Current Evidence and Future Perspectives

To date, non-alcoholic fatty liver disease (NAFLD) is the most frequent liver disease, affecting up to 70% of patients with diabetes. Currently, there are no specific drugs available for its treatment. Beyond their anti-hyperglycemic effect and the surprising role of cardio- and nephroprotection, GLP-1 receptor agonists (GLP-1 RAs) have shown a significant impact on body weight and clinical, biochemical and histological markers of fatty liver and fibrosis in patients with NAFLD. Therefore, GLP-1 RAs could be a weapon for the treatment of both diabetes mellitus and NAFLD. The aim of this review is to summarize the evidence currently available on the role of GLP-1 RAs in the treatment of NAFLD and to hypothesize potential future scenarios.

Efficacy and Safety of GLP-1 Receptor Agonists in Patients With Type 2 Diabetes Mellitus and Non-Alcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis

The prevalence of non-alcoholic fatty liver disease (NAFLD) in patients with type 2 diabetes mellitus (T2DM) is increasing and there is an urgent need for new treatment strategy to prevent progression of hepatic steatosis and fibrosis. We have performed a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the efficacy and safety of glucagon-like peptide-1 receptor agonists (GLP-1RAs) in the treatment of hepatic steatosis and fibrosis in patients with T2DM and NAFLD. The PubMed, Web of Science, Scopus, Embase and Cochrane Central Register of Controlled Trials databases were searched for articles that met the eligibility criteria to explore the efficacy and safety of GLP-1RAs in patients with T2DM and NAFLD. We assessed pooled data using a random/fixed-effects model according to the I² and p-values. Eight trials that included a total of 468 participants were eligible for inclusion in the review. For primary outcomes, administration of GLP-1RAs significantly decreased the content of intrahepatic adipose (IHA)[p=0.007, weight mean difference (WMD) -3.01, 95% confidence interval (CI) -4.75, -1.28], subcutaneous adipose tissue (SAT) (p<0.00001,WMD -28.53,95%CI -68.09,-26.31), and visceral adipose tissue (VAT) (p<0.0001,WMD -29.05,95%CI -42.90,-15.9). For secondary outcomes, GLP-1RAs produced a significant decrease in levels of alanine aminotransferase(ALT)(p=0.02, WMD -3.82, 95%CI -7.04, -0.60), aspartate aminotransferase (AST) (p=0.03, WMD -2.4, 95%CI -4.55,-0.25, I² = 49%), body weight (p<0.00001,WMD -3.48,95%CI -4.58,-2.37), body mass index (p<0.00001,WMD -1.07,95%CI -1.35,-0.78), circumference waist (p=0.0002,WMD -3.87, 95%CI -5.88, -1.86) fasting blood glucose (p=0.02, WMD -0.35, 95%CI -0.06, -0.05), HbA_1c (p<0.00001,WMD -0.39,95%CI -0.56,-0.22), HoMA-IR(p=0.005, WMD-1.51, 95%CI-0.87,-0.16), total cholesterol (p=0.0008, WMD -0.31, 95%CI -0.48, 0.13) and triglycerides (p=0.0008, WMD -0.27, 95%CI -0.43,-0.11) in comparison with the control regimens. The main adverse events associated with GLP-1RAs included mild-to-moderate gastrointestinal discomfort and nonsense hypoglycemia that resolved within a few weeks. GLP-1RAs were an effective treatment that improved intrahepatic visceral and subcutaneous adipose tissue, inflammatory markers, the anthropometric profiles and some metabolic indices in patients with T2DM and NAFLD, GLP-1RAs could be considered for use in these if there are no contraindications. Further studies are needed to understand the direct and indirect effects of GLP-1RAs on NAFLD and the potential mechanism via which they prevent its progression. Systematic Review Registration: PROSPERO, identifier CRD42021265806.

Glucagon-like peptide-1 receptor agonists in non-alcoholic fatty liver disease: An update

Non-alcoholic fatty liver disease (NAFLD) is the predominant cause of chronic liver disease worldwide. NAFLD progresses in some cases to non-alcoholic steatohepatitis (NASH), which is characterized, in addition to liver fat deposition, by hepatocyte ballooning, inflammation and liver fibrosis, and in some cases may lead to hepatocellular carcinoma. NAFLD prevalence increases along with the rising incidence of type 2 diabetes mellitus (T2DM). Currently, lifestyle interventions and weight loss are used as the major therapeutic strategy in the vast majority of patients with NAFLD. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are used in the management of T2DM and do not have major side effects like hypoglycemia. In patients with NAFLD, the GLP-1 receptor production is down-regulated. Recently, several animal and human studies have emphasized the role of GLP-1RAs in ameliorating liver fat accumulation, alleviating the inflammatory environment and preventing NAFLD progression to NASH. In this review, we summarize the updated literature data on the beneficial effects of GLP-1RAs in NAFLD/NASH. Finally, as GLP-1RAs seem to be an attractive therapeutic option for T2DM patients with concomitant NAFLD, we discuss whether GLP-1RAs should represent the first line pharmacotherapy for these patients.

Beneficial effect of anti-diabetic drugs for nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disorder and is associated with various metabolic diseases, including type 2 diabetes mellitus. There are no approved drugs for NAFLD, and the only approved treatment option is weight reduction. As insulin resistance plays an important role in the development of NAFLD, many anti-diabetic drugs have been evaluated for the treatment of NAFLD. Improvement of liver enzymes has been demonstrated by many anti-diabetic drugs, but histological assessment still remains insufficient. Pioglitazone could become the first-line therapy for T2DM patients with NAFLD, based on evidence of histological improvement in patients with biopsy-proven nonalcoholic steatohepatitis (NASH). Liraglutide, another promising alternative, is not yet recommended in patients with NAFLD/NASH due to limited evidence. Therefore, well-designed randomized controlled trials should be performed in the near future to demonstrate if and how anti-diabetic drugs can play a role in the treatment of NAFLD.

Gut-Pancreas-Liver Axis as a Target for Treatment of NAFLD/NASH

Non-alcoholic fatty liver disease (NAFLD) represents the most common form of chronic liver disease worldwide. Due to its association with obesity and diabetes and the fall in hepatitis C virus morbidity, cirrhosis in NAFLD is becoming the most frequent indication to liver transplantation, but the pathogenetic mechanisms are still not completely understood. The so-called gut-liver axis has gained enormous interest when data showed that its alteration can lead to NAFLD development and might favor the occurrence of non-alcoholic steatohepatitis (NASH). Moreover, several therapeutic approaches targeting the gut-pancreas-liver axis, e.g., incretins, showed promising results in NASH treatment. In this review, we describe the role of incretin hormones in NAFLD/NASH pathogenesis and treatment and how metagenomic/metabolomic alterations in the gut microbiota can lead to NASH in the presence of gut barrier modifications favoring the passage of bacteria or bacterial products in the portal circulation, i.e., bacterial translocation.

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) for the management of nonalcoholic fatty liver disease (NAFLD): A systematic review

There are no licensed drugs for nonalcoholic fatty liver disease (NAFLD), and there is a lack of consensus on the best outcome measures for controlled trials. This systematic review aimed to evaluate the efficacy of GLP-1 RAs in the management of NAFLD, the degree of heterogeneity in trial design and the robustness of conclusions drawn from these clinical trials. We searched publication databases and clinical trial registries through 2 November 2019 for clinical trials with NAFLD. We evaluated improvements in histological findings, noninvasive markers of hepatic steatosis, inflammation, and fibrosis, insulin resistance and anthropometric measures. Our final analysis included 24 clinical trials, comprising 6313 participants with a mean duration of 37 weeks. Four clinical trials, including RCT (n = 1), single-arm studies (n = 2) and case series studies (n = 1), used biopsy-confirmed liver histological change as their end-points. The remaining studies (n = 20) used surrogate end-points. GLP-1 RAs were effective for the improvement in hepatic inflammation, hepatic steatosis and fibrosis. More importantly, GLP-1 RAs showed promise in improving the histological features of NASH. In addition, 8 ongoing trials were identified. In this systematic review of published and ongoing clinical trials of the efficacy of GLP-1RAs for NAFLD, we found that GLP-1 RAs are effective for hepatic steatosis and inflammation, with the potential to reverse fibrosis. Further prospective studies of sufficient duration using histological end-points are needed to fully assess the efficacy of GLP-1 RAs in the management of NAFLD.

Nonalcoholic Fatty Liver Disease in Adults: Current Concepts in Etiology, Outcomes, and Management

Nonalcoholic fatty liver disease (NAFLD) is a spectrum of disease, extending from simple steatosis to inflammation and fibrosis with a significant risk for the development of cirrhosis. It is highly prevalent and is associated with significant adverse outcomes both through liver-specific morbidity and mortality but, perhaps more important, through adverse cardiovascular and metabolic outcomes. It is closely associated with type 2 diabetes and obesity, and both of these conditions drive progressive disease toward the more advanced stages. The mechanisms that govern hepatic lipid accumulation and the predisposition to inflammation and fibrosis are still not fully understood but reflect a complex interplay between metabolic target tissues including adipose and skeletal muscle, and immune and inflammatory cells. The ability to make an accurate assessment of disease stage (that relates to clinical outcome) can also be challenging. While liver biopsy is still regarded as the gold-standard investigative tool, there is an extensive literature on the search for novel noninvasive biomarkers and imaging modalities that aim to accurately reflect the stage of underlying disease. Finally, although no therapies are currently licensed for the treatment of NAFLD, there are interventions that appear to have proven efficacy in randomized controlled trials as well as an extensive emerging therapeutic landscape of new agents that target many of the fundamental pathophysiological processes that drive NAFLD. It is highly likely that over the next few years, new treatments with a specific license for the treatment of NAFLD will become available.

Effects of newer antidiabetic drugs on nonalcoholic fatty liver and steatohepatitis: Think out of the box!

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in Western societies and a major cause of hepatic disease worldwide. Its more severe type, namely nonalcoholic steatohepatitis (NASH), may result in the development of cirrhosis and hepatocellular carcinoma. NAFLD, and especially NASH, are also associated with increased cardiovascular morbidity and mortality. Type 2 diabetes mellitus (T2DM) predisposes to NAFLD development and progression via insulin resistance and hyperglycemia. It has also been reported that the majority of T2DM patients have NAFLD/NASH, thus potentially further increasing their cardiometabolic risk. Current guidelines recommend to screen for NAFLD in all T2DM patients and vice-versa. Lifestyle remains the first-line therapeutic option for NAFLD/NASH. Among antidiabetic drugs, pioglitazone was shown to improve histological features of NASH. More recently, there is an increasing interest regarding the effects of newer anti-diabetic drugs, such as dipeptidyl peptidase 4 inhibitors (DPP-4i), sodium glucose cotransporter 2 inhibitors (SGLT2i), and glucagon-like peptide-1 receptor agonists (GLP-1 RAs) on NAFLD/NASH. The present narrative review considers the up-to-date data on the impact of DPP-4i, SGLT2i, and GLP-1 RAs on biochemical and/or histological markers of NAFLD/NASH. The potential clinical implications of these findings in daily practice are also discussed. Taking into consideration the global increasing prevalence of NAFLD/NASH, therapeutic options that can prevent or treat this disease will exert considerable benefits on human health.

Future Perspectives on GLP-1 Receptor Agonists and GLP-1/glucagon Receptor Co-agonists in the Treatment of NAFLD

Along the obesity pandemic, the prevalence of non-alcoholic fatty liver disease (NAFLD), often regarded as the hepatic manifestation of the metabolic syndrome, increases worldwide representing now the prevalent liver disease in western countries. No pharmacotherapy is approved for the treatment of NAFLD and, currently, the cornerstone treatment is lifestyle modifications focusing on bodyweight loss, notoriously difficult to obtain and even more difficult to maintain. Thus, novel therapeutic approaches are highly demanded. Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RAs) are approved for the treatment of type 2 diabetes and obesity. They exert their body weight-lowering effect by reducing satiety and food intake. GLP-1RAs have also been shown to reduce liver inflammation and fibrosis. Furthermore, glucagon receptor agonism is being investigated for the treatment of NAFLD due to its appetite and food intake-reducing effects, as well as its ability to increase lipid oxidation and thermogenesis. Recent studies suggest that glucagon receptor signaling is disrupted in NAFLD, indicating that supra-physiological glucagon receptor agonism might represent a new NAFLD treatment target. The present review provides (1) an overview in the pathophysiology of NAFLD, including the potential involvement of GLP-1 and glucagon, (2) an introduction to the currently available GLP-1RAs and (3) outlines the potential of emerging GLP-1RAs and GLP-1/glucagon receptor co-agonists in the treatment of NAFLD.

Translational approaches: From fatty liver to non-alcoholic steatohepatitis

Over the past few decades, non-alcoholic fatty liver disease (NAFLD) has become one, if not the most common, cause of chronic liver disease affecting both adults and children. The increasing number of cases at an early age is the most worrying aspect of this pathology, since it provides more time for its evolution. The spectrum of this disease ranges from liver steatosis to steatohepatitis, fibrosis and in some cases, hepatocellular carcinoma. NAFLD may not always be considered a benign disease and hepatologists must be cautious in the presence of fatty liver. This should prompt the use of the available experimental models to understand better the pathogenesis and to develop a rational treatment of a disease that is dangerously increasing. In spite of the growing efforts, the pathogenesis of NAFLD is still poorly understood. In the present article we review the most relevant hypotheses and evidence that account for the progression of NAFLD to non-alcoholic steatohepatitis (NASH) and fibrosis. The available in vitro and in vivo experimental models of NASH are discussed and revised in terms of their validity in translational studies. These studies must be aimed at the discovery of the still unknown triggers or mediators that induce the progression of hepatic inflammation, apoptosis and fibrosis.