Clinical trial: insulin-sensitizing agents may reduce consequences of insulin resistance in individuals with non-alcoholic steatohepatitis

Metformin in the treatment of non-alcoholic fatty liver disease: safety, efficacy and mechanism

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease etiology worldwide. It encompasses a spectrum ranging from simple steatosis to non-alcoholic steatohepatitis. Although the physiopathology of NAFLD is partly known. Insulin-resistance plays a central role in the development and progression of NAFLD. Several studies have indicated that metformin, as an insulin sensitizer, effectively improves NAFLD and its related metabolic status. Metformin was effective in reducing enzyme levels in the short period, but very limited and controversial information are available on liver histology. Larger randomized controlled trials of sufficient duration using clearly defined histological endpoints are needed to fully assess the efficacy of this drug in modifying the natural history of NAFLD.

Impact of sequential proton density fat fraction for quantification of hepatic steatosis in nonalcoholic fatty liver disease

OBJECTIVE

To determine the utility of sequential MRI-estimated proton density fat fraction (MRI-PDFF) for quantification of the longitudinal changes in liver fat content in individuals with nonalcoholic fatty liver disease (NAFLD).

METHODS

A total of 18 consecutive individuals (M/F: 10/8, mean age: 47.7±9.8 years) diagnosed with NAFLD, who underwent sequential PDFF calculations for the quantification of hepatic steatosis at two different time points, were included in the study. All patients underwent T1-independent volumetric multi-echo gradient-echo imaging with T2* correction and spectral fat modeling.

RESULTS

A close correlation for quantification of hepatic steatosis between the initial MRI-PDFF and liver biopsy was observed (rs=0.758, p<0.001). The median interval between two sequential MRI-PDFF measurements was 184 days. From baseline to the end of the follow-up period, serum GGT level and homeostasis model assessment score were significantly improved (p=0.015, p=0.006, respectively), whereas BMI, serum AST, and ALT levels were slightly decreased. MRI-PDFFs were significantly improved (p=0.004). A good correlation between two sequential MRI-PDFF calculations was observed (rs=0.714, p=0.001). With linear regression analyses, only delta serum ALT levels had a significant effect on delta MRI-PDFF calculations (r2=38.6%, p=0.006). At least 5.9% improvement in MRI-PDFF is needed to achieve a normalized abnormal ALT level. The improvement of MRI-PDFF score was associated with the improvement of biochemical parameters in patients who had improvement in delta MRI-PDFF (p<0.05).

CONCLUSIONS

MRI-PDFF can be used for the quantification of the longitudinal changes of hepatic steatosis. The changes in serum ALT levels significantly reflected changes in MRI-PDFF in patients with NAFLD.

Insulin sensitizers for the treatment of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the leading cause of liver disease in the Western world and is closely associated with metabolic syndrome, which includes hypertension, central obesity, dyslipidemia and insulin resistance. NAFLD includes a wide spectrum of liver alterations, ranging from simple hepatic steatosis to variable degrees of fibrosis, cirrhosis and even hepatocellular carcinoma. Although the etiology and progression of the disorder remain poorly understood, insulin resistance is considered to play a pivotal role in the pathogenesis. Insulin sensitizers such as biguanides, thiazolidinediones (TZDs), glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase 4 inhibitors have been studied as therapeutic approaches for NAFLD in recent years. Metformin improves insulin sensitivity and serum alanine transaminase and aspartate transaminase (ALT/AST) levels in the majority of subjects; however, it has no significant effect on liver histology. TZDs improve insulin sensitivity, serum ALT/AST levels and histology in some cases, but there are some concerns about the safety of long-term therapy. Selection of appropriate patients for avoiding side effects and the treatment of underlying disease are the main points. These drugs are the best choice for the treatment of NAFLD in patients with type 2 DM who are also candidates for treatment with an insulin sensitizer. The present review provides an overview of insulin sensitizers in the treatment of NAFLD.

Liver disease and diabetes: association, pathophysiology, and management

Diabetes is associated with a spectrum of liver diseases including nonalcoholic liver disease, steatohepatitis, and liver cirrhosis with their increased complications and mortality. Hepatitis C virus (HCV) and its associated liver cirrhosis has been associated with diabetes through insulin resistance. Cryptogenic diabetes occurs as a consequence of liver cirrhosis with the pathophysiology being complex, but mostly attributed to the increased insulin resistance in muscle, liver, and adipose tissue. As for the management of diabetes in patients with liver disease, lifestyle modification plays an important role. Oral diabetic medications are contraindicated in patients with advanced liver diseases with associated cirrhosis, ascites, or encephalopathy. As for stable liver disease, metformin and thiazolenediones have shown mixed results, with some showing them to be effective in improving liver transaminases in addition to histological improvement in steatosis and inflammation. α-glucosidase inhibitors may be helpful in decreasing hepatic encephalopathy. Upregulation of Dipeptidyl peptidase-4 (DPP-4) has been suggested as a possible pathogenetic mechanism for HCV-related insulin resistance, and treatment with DPP-4 inhibitors could improve insulin sensitivity in diabetic patients with liver disease. Patients with impaired liver function with associated insulin resistance may need increased insulin requirements. On the other hand patients with altered liver metabolism might need decreased insulin requirements.

Effect of metformin on ballooning degeneration in nonalcoholic steatohepatitis (NASH): when to use metformin in nonalcoholic fatty liver disease (NAFLD)

The key histologic feature of nonalcoholic steatohepatitis (NASH) is hepatocellular ballooning (HB). It plays an important role in NASH progression and is an independent predictor of liver mortality. In this review, we identified all studies using metformin in the treatment of nonalcoholic fatty liver disease (NAFLD) that included pre- and post-treatment liver biopsies. We specifically reviewed the effects of metformin on HB. Improved HB was noted in pediatric populations and in those adult patients who were able to lose weight and improve or normalize transaminases during therapy. Previous studies have supported the beneficial effects of metformin in reduction of body weight, improvement of insulin resistance, prevention of complications related to diabetes and chemo-preventive benefits in reducing hepatocellular carcinoma. All these effects make it an attractive treatment consideration for patients with diabetes, and prediabetes who have co-existing NAFLD. Future studies are warranted in order to confirm this effect of metformin on HB and its association with improving long-term outcomes in patients with NAFLD.

The therapy of insulin resistance in other diseases besides type 2 diabetes

Insulin resistance is a clinical condition shared by many diseases besides type 2 diabetes (T2DM) such as obesity, polycystic ovary syndrome (PCOS) and non-alcoholic fatty liver disease (NAFLD). Experimental evidence, produced over the years, suggests that metformin has many benefits in the treatment of these diseases. Metformin is a first-line drug in the treatment of overweight and obese type 2 diabetic patients, offering a selective pathophysiological approach by its effect on insulin resistance. Moreover, a number of studies have established the favorable effect of metformin on body weight, not only when evaluating BMI, but also if body mass composition is considered, through the reduction of fat mass. In addition, it reduces insulin resistance, hyperinsulinemia, lipid parameters, arterial hypertension and endothelial dysfunction. In particular, a new formulation of metformin extended-release (ER) is now available with different formulation in different countries. Metformin ER delivers the active drug through hydrated polymers which expand safe uptake of fluid, prolonging gastric transit and delaying drug absorption in the upper gastrointestinal tract. In addition, Metformin ER causes a small, but statistically significant decrease in BMI, when added to a lifestyle intervention program in obese adolescents. Because of the suggested benefits for the treatment of insulin resistance in many clinical conditions, besides type 2 diabetes, the prospective exists that more indications for metformin treatment are becoming a reality.

Nonalcoholic Fatty liver: a possible new target for type 2 diabetes prevention and treatment

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder worldwide. Several lines of evidence have indicated a pathogenic role of insulin resistance, and a strong association with type 2 diabetes (T2MD) and metabolic syndrome. Importantly, NAFLD appears to enhance the risk for T2MD, as well as worsen glycemic control and cardiovascular disease in diabetic patients. In turn, T2MD may promote NAFLD progression. The opportunity to take into account NAFLD in T2MD prevention and care has stimulated several clinical studies in which antidiabetic drugs, such as metformin, thiazolidinediones, GLP-1 analogues and DPP-4 inhibitors have been evaluated in NAFLD patients. In this review, we provide an overview of preclinical and clinical evidences on the possible efficacy of antidiabetic drugs in NAFLD treatment. Overall, available data suggest that metformin has beneficial effects on body weight reduction and metabolic parameters, with uncertain effects on liver histology, while pioglitazone may improve liver histology. Few data, mostly preclinical, are available on DPP4 inhibitors and GLP-1 analogues. The heterogeneity of these studies and the small number of patients do not allow for firm conclusions about treatment guidelines, and further randomized, controlled studies are needed.

Pharmacologic therapy for nonalcoholic fatty liver disease in adults

Nonalcoholic fatty liver disease (NAFLD) is characterized by the accumulation of triglycerides in hepatocytes in the absence of excessive alcohol intake, ranging in severity from simple steatosis to nonalcoholic steatohepatitis (NASH). Nonalcoholic steatohepatitis can ultimately progress to cirrhosis and hepatocellular carcinoma. NAFLD is associated with cardiometabolic risk factors and is the most common chronic liver disease among adults in the Western Hemisphere. Although simple steatosis is generally considered a self-limiting disease, evidence suggests an increased risk of cardiovascular disease, and, less conclusively, mortality, among individuals with NAFLD and/or NASH. The current standard of care for the treatment of patients with NAFLD focuses on lifestyle interventions, particularly diet and exercise. There is a lack of consensus regarding the most effective and appropriate pharmacologic therapy. A PubMed search was conducted using the medical subject heading terms "fatty liver" and "steatohepatitis." This review focuses on the current pharmacologic options available for treating adults with NAFLD and/or NASH. Continued investigation of drugs or combinations that improve NAFLD progression is crucial. Clinicians, particularly pharmacists, must take an active role in identification and appropriate selection of pharmacotherapy for NAFLD.

Adiponectin: a key playmaker adipocytokine in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome and can progress to cirrhosis, liver failure, and hepatocellular carcinoma. In the last two decades, the prevalence of NAFLD has been growing in most developed countries, mainly as a consequence of its close association with obesity and diabetes mellitus. The exact pathogenesis of NAFLD and especially the mechanisms leading to disease progression have not been completely understood. Adipocytes produce and secrete several bioactive substances known as adipocytokines which are implicated in the pathogenesis of the disease. Among them, adiponectin is an insulin-sensitizing adipocytokine possessing multiple beneficial effects on obesity-related medical complication. This review focuses on the role of adiponectin in NAFLD pathogenesis and its potential use as a diagnostic tool but also as therapeutic target for NAFLD management.

Peroxisome proliferator-activated receptor-γ as a therapeutic target for hepatic fibrosis: from bench to bedside

Hepatic fibrosis is a dynamic chronic liver disease occurring as a consequence of wound-healing responses to various hepatic injuries. This disorder is one of primary predictors for liver-associated morbidity and mortality worldwide. To date, no pharmacological agent has been approved for hepatic fibrosis or could be recommended for routine use in clinical context. Cellular and molecular understanding of hepatic fibrosis has revealed that peroxisome proliferator-activated receptor-γ (PPARγ), the functioning receptor for antidiabetic thiazolidinediones, plays a pivotal role in the pathobiology of hepatic stellate cells (HSCs), whose activation is the central event in the pathogenesis of hepatic fibrosis. Activation of PPARγ inhibits HSC collagen production and modulates HSC adipogenic phenotype at transcriptional and epigenetic levels. These molecular insights indicate PPARγ as a promising drug target for antifibrotic chemotherapy. Intensive animal studies have demonstrated that stimulation of PPARγ regulatory system through gene therapy approaches and PPARγ ligands has therapeutic promise for hepatic fibrosis induced by a variety of etiologies. At the same time, thiazolidinedione agents have been investigated for their clinical benefits primarily in patients with nonalcoholic steatohepatitis, a common metabolic liver disorder with high potential to progress to fibrosis and liver-related death. Although some studies have shown initial promise, none has established long-term efficacy in well-controlled randomized clinical trials. This comprehensive review covers the 10-year discoveries of the molecular basis for PPARγ regulation of HSC pathophysiology and then focuses on the animal investigations and clinical trials of various therapeutic modalities targeting PPARγ for hepatic fibrosis.

Metformin in non-alcoholic fatty liver disease: A systematic review and meta-analysis

Non-alcoholic fatty liver disease (NAFLD) related to insulin resistance (IR) is a growing global health concern. Recent studies have indicated that metformin could improve IR and may be beneficial in the treatment of NAFLD. This study aimed to assess the beneficial or harmful effects of metformin in NAFLD. We searched Medline and four other databases during April 2012. Selection criteria were randomized clinical trials comparing metformin with placebo or other interventions for treating NAFLD patients. The primary outcome was histological response. The secondary outcomes included alanine aminotransferase (ALT), aspartate aminotransferase (AST), homeostasis model assessment of IR (HOMA-IR), body mass index (BMI) and adverse events. Dichotomous data were reported as odds ratio (OR), while continuous data were calculated as the mean difference (MD), both with 95% confidence intervals (CI). Random and fixed effects meta-analyses were performed. Nine studies were included, involving 417 participants, and conducted for a time period ranging from 4 to 12 months. In the treated participants, improvements were observed in ALT (MD, -8.12 U/l; P=0.03), AST (MD, -4.52 U/l; P=0.04), HOMA-IR (MD, -0.61; P=0.005) and BMI (MD, -0.82 kg/m²; P=0.04), but not in histological response: steatosis (P=0.66), inflammation (P=0.91), hepatocellular ballooning (P= 0.25) and fibrosis (P= 0.90). Sub-analysis of non-alcoholic fatty steatohepatitis showed that metformin failed to improve any pooled outcome. Adverse events were poorly reported. Current information indicates that metformin improves liver function, HOMA-IR and BMI to some extent, but not histological response in NAFLD patients. This finding could serve as a stimulus for future studies investigating issues such as dose-responsiveness, safety and patient tolerance to metformin therapy.

Metformin in non-alcoholic fatty liver disease: A systematic review and meta-analysis

Non-alcoholic fatty liver disease (NAFLD) related to insulin resistance (IR) is a growing global health concern. Recent studies have indicated that metformin could improve IR and may be beneficial in the treatment of NAFLD. This study aimed to assess the beneficial or harmful effects of metformin in NAFLD. We searched Medline and four other databases during April 2012. Selection criteria were randomized clinical trials comparing metformin with placebo or other interventions for treating NAFLD patients. The primary outcome was histological response. The secondary outcomes included alanine aminotransferase (ALT), aspartate aminotransferase (AST), homeostasis model assessment of IR (HOMA-IR), body mass index (BMI) and adverse events. Dichotomous data were reported as odds ratio (OR), while continuous data were calculated as the mean difference (MD), both with 95% confidence intervals (CI). Random and fixed effects meta-analyses were performed. Nine studies were included, involving 417 participants, and conducted for a time period ranging from 4 to 12 months. In the treated participants, improvements were observed in ALT (MD, -8.12 U/l; P=0.03), AST (MD, -4.52 U/l; P=0.04), HOMA-IR (MD, -0.61; P=0.005) and BMI (MD, -0.82 kg/m²; P=0.04), but not in histological response: steatosis (P=0.66), inflammation (P=0.91), hepatocellular ballooning (P= 0.25) and fibrosis (P= 0.90). Sub-analysis of non-alcoholic fatty steatohepatitis showed that metformin failed to improve any pooled outcome. Adverse events were poorly reported. Current information indicates that metformin improves liver function, HOMA-IR and BMI to some extent, but not histological response in NAFLD patients. This finding could serve as a stimulus for future studies investigating issues such as dose-responsiveness, safety and patient tolerance to metformin therapy.

Management of nonalcoholic steatohepatitis: an evidence-based approach

Nonalcoholic fatty liver disease (NAFLD) and its progressive form, nonalcoholic steatohepatitis (NASH), are an increasingly common cause of chronic liver disease in the developed world, with NASH projected to be the leading cause of liver transplantation in the United States by 2020. This review of NASH management addresses current data from the perspective of levels of evidence for therapeutic options in NASH, including lifestyle modification, drug therapies, and bariatric surgery. In particular, behavioral therapies to assist patients in adopting lifestyle changes are highlighted and a research agenda for future NASH management is presented.

Management of Non-alcoholic Fatty Liver Disease and Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of abnormal liver enzymes and chronic liver disease in the US with expected rise in incidence paralleling the epidemic of obesity. A subset of patients with NAFLD have the progressive form of NAFLD that is termed non-alcoholic steatohepatitis (NASH), which is characterized by specific features on liver histology including hepatocellular ballooning degeneration, lobular inflammation, and zone-3 steatosis with or without peri-sinusoidal fibrosis. Non-alcoholic steatohepatitis can progress to cirrhosis and result in liver-related death. Insulin resistance is commonly seen in patients with NASH and often co-exists with other features of the metabolic syndrome including hypertension, hyperlipidemia, and obesity. Although weight loss through lifestyle modifications including dietary changes and increased physical exercise remains the backbone of management of NASH, it has proved challenging for patients to achieve and maintain weight loss goals. Thus, it is often necessary to couple lifestyle changes with another pharmacologic treatment for NASH. Insulin sensitizers including the biguanides (metformin), thiazolidinediones (pioglitazone and rosiglitazone), and glucagon-like peptide-1 receptor agonists (exenatide) are large groups of medications that have been studied for the treatment of NASH. Other agents with anti-inflammatory, anti-apoptotic, or anti-fibrotic properties which have been studied in NASH include vitamin E, pentoxifylline, betaine, and ursodeoxycholic acid. This review will provide a detailed summary on the clinical data behind the full spectrum of treatments that exist for NASH and suggest management recommendations.

Impact of current treatments on liver disease, glucose metabolism and cardiovascular risk in non-alcoholic fatty liver disease (NAFLD): a systematic review and meta-analysis of randomised trials

AIMS/HYPOTHESIS

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum ranging from simple steatosis to non-alcoholic steatohepatitis (NASH): NAFLD causes an increased risk of cardiovascular disease, diabetes and liver-related complications (the latter confined to NASH). The effect of proposed treatments on liver disease, glucose metabolism and cardiovascular risk in NAFLD is unknown. We reviewed the evidence for the management of liver disease and cardio-metabolic risk in NAFLD.

METHODS

Publications through November 2011 were systematically reviewed by two authors. Outcomes evaluated though standard methods were: histological/radiological/biochemical features of NAFLD, variables of glucose metabolism and cardiovascular risk factors. Seventy-eight randomised trials were included (38 in NASH, 40 in NAFLD): 41% assessed post-treatment histology, 71% assessed glucose metabolism and 88% assessed cardiovascular risk factors. Lifestyle intervention, thiazolidinediones, metformin and antioxidants were most extensively evaluated.

RESULTS

Lifestyle-induced weight loss was safe and improved cardio-metabolic risk profile; a weight loss ≥7% improved histological disease activity, but was achieved by <50% patients. Statins and polyunsaturated fatty acids improved steatosis, but their effects on liver histology are unknown. Thiazolidinediones improved histological disease activity, glucose, lipid and inflammatory variables and delayed fibrosis progression. Pioglitazone also improved blood pressure. Weight gain (up to 4.8%) was common. Antioxidants yielded mixed histological results: vitamin E improved histological disease activity when administered for 2 years, but increased insulin resistance and plasma triacylglycerols.

CONCLUSIONS/INTERPRETATION

Weight loss is safe, and improves liver histology and cardio-metabolic profile. For patients not responding to lifestyle intervention, pioglitazone improves histological disease activity, slows fibrosis progression and extensively ameliorates cardio-metabolic endpoints. Further randomised controlled trials (RCTs) of adequate size and duration will assess long-term safety and efficacy of proposed treatments on clinical outcomes.

Meta-analysis: pioglitazone improves liver histology and fibrosis in patients with non-alcoholic steatohepatitis

BACKGROUND

Thiazolidinediones (TZDs) have been used in the treatment of non-alcoholic steatohepatitis (NASH). However, the magnitude of treatment response associated with TZDs in improving liver histology in NASH has not been quantified systematically.

AIM

To conduct a meta-analysis of randomised, placebo-controlled clinical trials (RPCTs) using pioglitazone and rosiglitazone in the treatment of NASH.

METHODS

Pubmed/MEDLINE and Cochrane Central Register of Controlled Trials 2010 were searched until September 2010 and four RPCTs were identified. Peto odds ratios (ORs) and their respective 95% confidence intervals (CIs) were used to assess the efficacy of TZDs in improving liver histological parameters.

RESULTS

Four good quality RPCTs derived from three continents were included. The meta-analysis showed that TZDs (n = 169) were significantly better than placebo (n = 165) in improving ballooning degeneration, lobular inflammation and steatosis with combined ORs of 2.11 (95% CI, 1.33-3.36), 2.58 (95% CI, 1.68-3.97) and 3.39 (95% CI, 2.19-5.25) respectively. The improvement in combined necroinflammation with TZD (n = 58) vs. placebo (n = 52) was also statistically significant (combined OR 6.52[95% CI, 3.03-14.06]), but improvement in fibrosis was not. When pioglitazone (n = 137) was analysed alone, the improvement in fibrosis with pioglitazone (n = 137) vs. placebo (n = 134) (combined OR 1.68 [95% CI, 1.02-2.77]) was statistically significant. The total body fat slightly decreased in the control, while it markedly and highly significantly increased with TZD treatment.

CONCLUSIONS

Thiazolidinediones significantly improve ballooning degeneration, lobular inflammation, steatosis and combined necroinflammation in patients with NASH. Pioglitazone may improve fibrosis. Larger randomised, placebo-controlled clinical trials are needed to examine the efficacy of thiazolidinediones in improving NASH fibrosis.

The role of metformin in the management of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disorder worldwide. Its prevalence ranges 10–24% in the general population, reaching 60–95% and 28–55% in obese and diabetic patients, respectively. Although the etiology of NAFLD is still unclear, several lines of evidences have indicated a pathogenetic role of insulin resistance in this disorder. This concept has stimulated several clinical studies where antidiabetic drugs, such as insulin sensitizers including metformin, have been evaluated in insulin-resistant, NAFLD patients. These studies indicate that metformin might be of benefit in the treatment of NAFLD, also in nondiabetic patients, when associated to hypocaloric diet and weight control. However, the heterogeneity of these studies still prevents us from reaching firm conclusions about treatment guidelines. Moreover, metformin could have beneficial tissue-specific effects in NAFLD patients irrespective of its effects as insulin sensitizer.

Non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) refers to the accumulation of hepatic steatosis not due to excess alcohol consumption. The prevalence of NAFLD is up to 30% in developed countries and nearly 10% in developing nations, making NAFLD the most common liver condition in the world. The pathogenesis of NAFLD is related to insulin resistance and, thus, it is frequently found in individuals who have central obesity or diabetes. Insulin resistance and excess adiposity are associated with increased lipid influx into the liver and increased de novo hepatic lipogenesis, promoting hepatic triglyceride accumulation. Defects in lipid utilization via mitochondrial oxidation and lipid export may also contribute to hepatic lipid build-up. Adipocytokine alterations, lipotoxicity from saturated fatty acids and fructose have been all been implicated in causing hepatocyte injury in NAFLD through pathways involving oxidative and endoplasmic reticulum stress. Clinically, NAFLD is commonly asymptomatic and frequently detected incidentally by blood liver function tests or imaging performed for other reasons. Subjects with NAFLD have a higher mortality rate than the general population and are at increased risk of developing cardiovascular disease and diabetes in the future. Histologically, NAFLD occurs as a spectrum from mild hepatic steatosis only, to non-alcoholic steatohepatitis (NASH) characterized by hepatocellular injury and inflammation, to cirrhosis. A diagnosis of NASH with associated fibrosis heralds a more significant prognosis as it is more likely to progressive to cirrhosis with complications of hepatic failure and hepatocellular carcinoma. Currently, the diagnosis of NASH requires a liver biopsy, however, serum based markers of hepatocyte apoptosis such as cytokeratin-18 fragments offer promise as accurate non-invasive diagnostic tests. Treatment of NAFLD revolves around addressing concomitant metabolic risk factors and improving insulin resistance through weight loss measures and exercise. Insulin sensitizing agents such as pioglitazone and anti-oxidant agents such as vitamin E show some promise in improving liver histology in patients with NASH, however, the long-term benefit of these medications has not been demonstrated.

The role of thiazolidinediones in non-alcoholic steatohepatitis - a systematic review and meta analysis

BACKGROUND & AIMS

Non alcoholic steatohepatitis (NASH) has no approved pharmacological therapy. Insulin sensitisers such as thiazolidinediones ameliorate insulin resistance and are a potential therapeutic option. We performed a systematic review and meta-analysis of the effect of thiazolidinediones on histological and biochemical variables in NASH.

METHODS

Two reviewers searched Medline, Embase, Cochrane Central, international meeting abstracts, reference lists, and contacted experts. Inclusion criteria were randomized trials of people with NASH receiving thiazolidinediones, compared with placebo or other treatments. Methodological quality was assessed in domains suggested by the Cochrane Collaboration. The primary outcome was histological improvement (fibrosis, steatosis, inflammation, hepatocellular ballooning, and NAS score). Secondary outcomes included change in alanine transaminase, insulin resistance, body mass index, weight, and adverse events. Meta-analysis used random effects with dichotomous outcomes as relative risk (RR) and continuous outcomes as mean difference (MD), both with 95% confidence intervals (CI).

RESULTS

Of seven randomized trials (n=489) with histological outcomes, four were placebo controlled (n=355). Methodological quality was variable although better for placebo controlled studies. Treated participants showed improvement in fibrosis (RR 1.38, CI 1.01-1.89), steatosis (RR 2.03, CI 1.57-2.62), inflammation (RR 1.71, CI 1.32-2.21), and hepatocellular ballooning (RR 1.62, CI 1.15-2.28). Treatment increased weight by an average of 4.4 kg (CI 2.6-5.2 kg). Adverse event reporting was inconsistent and only one trial assessed quality of life.

CONCLUSIONS

Thiazolidinediones modestly improve histological variables including fibrosis and hepatocellular ballooning, but at the cost of significant weight gain. Trials of longer duration and reporting of patient oriented outcomes would be informative.

The role of insulin-sensitizing agents in the treatment of nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome, which includes dyslipidemia, central obesity, hypertension, and insulin resistance. These diseases collectively and individually increase the risk of cardiovascular disease. Nonalcoholic steatohepatitis (NASH) is a subset of NAFLD that can progress to cirrhosis in up to 30% of patients and lead to decompensated liver disease requiring liver transplantation in many patients. Insulin resistance is the pathophysiological hallmark of NASH and addressing insulin resistance is an important aspect of NASH management. Lifestyle modifications with diet and exercise improve insulin sensitivity and are the cornerstone of therapy, but are often difficult to maintain long term. Not surprisingly, insulin-sensitizing agents have been a focus of pharmacologic investigation in NASH. Insulin sensitizers such as the thiazolidinediones, biguanides, glucagon-like peptide-1 receptor agonists, and the dipeptidyl peptidase IV inhibitors, also known as incretins, will be discussed with respect to their mechanism of action and how these drugs might target aspects of NASH pathophysiology. Finally, we will summarize the available clinical data and review both the risks and benefits of insulin sensitizers in the treatment of NASH.

Pharmacological therapy of nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH), unlike simple steatosis, is a potentially progressive disease. Various types of drugs have been explored for the treatment of NASH. We reviewed the various therapies available, with particular emphasis on their efficacy for the improvement of hepatic fibrosis. Treatments for NASH included lipase-inhibiting agents, drugs that target components of metabolic syndrome, antioxidants, liver cytoprotectants, and suppressors of inflammatory cytokines. Alanine transaminase levels were significantly decreased and the grade of histologic features other than fibrosis was significantly improved in more than 75% of treatment arms across studies, yet the stage of liver fibrosis was significantly improved in less than 30% of treatment arms. Recently, drugs such as peroxisome proliferator-activated receptor-γ agonists have received attention for their anti-fibrotic effect. However, due to a lack of large-scale, high quality, long-term clinical trials, the utility of any particular treatment for NASH is not yet clear. Further clinical studies are needed to evaluate the efficacy and safety of individual drugs.

Efficacy of long-term ezetimibe therapy in patients with nonalcoholic fatty liver disease

BACKGROUND

Hyperlipidemia, insulin resistance, and oxidative stress can heavily contribute to the initiation and progression of nonalcoholic fatty liver disease (NAFLD). Currently, there is no established treatment for this disease. Recently, several studies have shown that ezetimibe (EZ), a lipid-lowering drug, attenuates liver steatosis in an experimental NAFLD model. This study was designed to assess the efficacy of long-term EZ monotherapy in patients with NAFLD.

METHODS

A total of 45 patients with newly diagnosed liver biopsy-proven NAFLD were treated with EZ (10 mg/day) for 24 months. NAFLD-related biochemical parameters, imaging by computerized tomography, and liver biopsy were studied before and after treatment.

RESULTS

Ezetimibe therapy significantly improved NAFLD-related metabolic parameters including visceral fat area, fasting insulin, homeostasis model assessment of insulin resistance (HOMA-R), triglycerides, total cholesterol, low-density lipoprotein cholesterol (LDL-Ch), oxidative-LDL, the net electronegative charge modified-LDL, profiles of lipoprotein particle size and fatty acids component, and estimated desaturase activity. EZ therapy also significantly lowered serum alanine aminotransferase and high-sensitivity C-reactive protein levels, whereas no significant changes were found in serum type IV collagen 7S, adiponectin, leptin, and resistin levels. Histological features of steatosis grade (P = 0.0003), necroinflammatory grade (P = 0.0456), ballooning score (P = 0.0253), and NAFLD activity score (NAS) (P = 0.0007) were significantly improved from baseline. However, the fibrosis stage was not significantly (P = 0.6547) changed.

CONCLUSION

The results in this study suggest that the long-term EZ therapy can lead to improvement in metabolic, biochemical, and histological abnormalities of NAFLD. Therefore, EZ may be a promising agent for treatment of NAFLD.

Therapeutic trials in nonalcoholic steatohepatitis: insulin sensitizers and related methodological issues

Insulin sensitizers are attractive candidate therapies for nonalcoholic steatohepatitis mainly because of the strong association between this disease and insulin resistance. This review provides a critical overview of the mechanisms of action, clinical trial results, and safety issues of metformin and glitazones in nonalcoholic steatohepatitis. It also highlights methodological challenges for trial design and proposes endpoints for future proof of principle, registrational, and postmarketing trials.

Meta-analysis: insulin sensitizers for the treatment of non-alcoholic steatohepatitis

BACKGROUND

Non-alcoholic fatty liver disease generally has a benign course; however, patients with non-alcoholic steatohepatitis (NASH) may progress to cirrhosis and hepatocellular carcinoma. Currently, there is a lack of consensus about optimal NASH treatment.

AIM

To assess the efficacy of insulin-sensitizing agents on histological and biochemical outcomes in randomized control trials of biopsy-proven NASH.

METHODS

Multiple online databases and conference abstracts were searched. Random effects meta-analyses were performed, with assessment for heterogeneity and publication bias.

RESULTS

Nine trials were included; five trials using thiazolidinediones (glitazones), three using metformin and one trial using both drugs. There was no publication bias. Compared with controls, glitazones resulted in improved steatosis (WMD = 0.57, 95% CI 0.36-0.77, P = <0.001), hepatocyte ballooning (WMD = 0.36, 95% CI 0.24-0.49, P < 0.001) and ALT (WMD = 16.4, 95% CI 7.7-25.0, P < 0.001), but not inflammation (P = 0.09) or fibrosis (P = 0.11). In patients without diabetes, glitazones significantly improved all histological and biochemical outcomes, most importantly including fibrosis (WMD = 0.29, 95% CI 0.078-0.51, P = 0.008). Metformin failed to improve any pooled outcome.

CONCLUSIONS

Treatment of NASH with glitazones, but not metformin, demonstrates a significant histological and biochemical benefit, especially in patients without diabetes. Additional studies are needed to investigate long-term outcomes of glitazone therapy in patients without diabetes.

Clinical syndromes and consequences of antiretroviral-related hepatotoxicity

Highly active antiretroviral therapy (HAART)-related hepatotoxicity complicates the management of patients infected with human immunodeficiency virus (HIV), increases medical costs, alters the prescription patterns, and affects the guideline recommendations. Among the clinical consequences derived from HAART-related liver toxicity, hypersensitivity reactions and lactic acidosis are recognized as acute events with potential to evolve into fatal cases, whereas there seems to be other syndromes not as well characterized but of equal concern as possible long-term liver complications. Belonging to the latter category of syndrome, HAART-related nonalcoholic steatohepatitis, liver fibrosis, portal hypertension, and nodular regenerative hyperplasia are discussed in this review. Updated information on liver toxicity of current antiretroviral drugs, including the most recently licensed, is provided. Management and prevention of liver toxicity among HIV-infected patients treated with HAART are reviewed as well.

A meta-analysis of randomized trials for the treatment of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) encompasses a histological spectrum ranging from simple steatosis to nonalcoholic steatohepatitis (NASH). NAFLD carries a higher risk of cardio-metabolic and liver-related complications, the latter being confined to NASH and demanding specific treatment. We assessed the efficacy of proposed treatments for NAFLD/NASH by reviewing reports of randomized controlled trials (RCTs) on online databases and national and international meeting abstracts through January 2010. Primary outcome measure was histological improvement; secondary outcome was biochemical improvement; improvement in radiological steatosis was also evaluated. Two reviewers extracted articles using predefined quality indicators, independently and in duplicate. Main outcomes of randomized controlled trials (RCTs) were pooled using random-effects or fixed-effects models. Publication bias was assessed by funnel plots. Forty-nine RCTs (30 in NASH) were included: 23 RCTs (22 in NASH, 1 in NAFLD) had post-treatment histology. Most RCTs were small and did not exceed 1-year duration. Weight loss, thiazolidinediones (especially pioglitazone), and antioxidants were most extensively evaluated. Weight loss was safe and dose-dependently improved histological disease activity in NASH, but more than 50% of patients failed to achieve target weight loss. Thiazolidinediones improved steatosis and inflammation but yielded significant weight gain. RCTs with antioxidants yielded conflicting results and were heterogeneous with respect to type and dose of drug, duration, implementation of lifestyle intervention. Among the other agents, pentoxifylline, telmisartan and L-carnitine improved liver histology in at least 1 RCT in NASH; polyunsaturated fatty acid (PUFA) ameliorated biochemical and radiological markers of NAFLD. Other approaches yielded negative results.

CONCLUSION

Well-designed RCTs of adequate size and duration, with histological endpoints, are needed to assess long-term safety and efficacy of proposed treatments on patient-oriented clinical outcomes.

Insulin sensitizers in nonalcoholic fatty liver disease and steatohepatitis: Current status

Nonalcoholic fatty liver disease (NAFLD), first described in 1980, is now recognized as one of the most common causes of elevated liver enzymes and chronic liver disease in Western countries. The incidence of NAFLD in both adults and children is rising, in conjunction with the burgeoning epidemics of obesity and type 2 diabetes mellitus. NAFLD often coexists with other sequelae of the metabolic syndrome: central obesity, type 2 diabetes, hypertension, and hyperlipidemia. NAFLD encompasses a spectrum of pathologic liver diseases ranging from simple hepatic steatosis to a predominant lobular necro-inflammation, with or without centrilobular fibrosis (called nonalcoholic steatohepatitis or NASH). NASH can progress to cirrhosis, decompensated liver disease, and hepatocellular carcinoma. Though the natural history of NASH is still not clearly defined, it has been observed to progress to cirrhosis in 15%-220% of those affected. Insulin resistance is nearly universal in NASH and is thought to play an important role in its pathogenesis leading to dysregulated lipid metabolism. The prevalence of insulin resistance is reported in the general population to be approaching 45%, suggesting that NAFLD and NASH will contin nue to be an important public health concern. To date, NASH has proven to be a difficult disease to treat. Front-line therapy with lifestyle modifications resulting in weight loss through decreased caloric intake and moderate exercise is generally believed to be beneficial in patients with NASH, but is often difficult to maintain long term. Given that insulin resistance plays a dominant role in the pathogenesis, many studies have examined the use of insulin sensitizers: the biguanides (metformin), thiazolidinediones (pioglitazone, troglitazone, and rosiglitazone), glucagon-like peptide-1-receptor agonists, or incretins (exenatide)in NASH. This review will provide an overview of insulin resistance in NAFLD and provide a detailed summary on the clinical data regarding the use of insulin sensitizers in NASH.

Evidence-based and potential benefits of metformin in the polycystic ovary syndrome: a comprehensive review

Metformin is an insulin sensitizer widely used for the treatment of patients affected by type 2 diabetes mellitus. Because many women with polycystic ovary syndrome (PCOS) are insulin resistant, metformin was introduced in clinical practice to treat these patients also. Moreover, metformin's effect has other targets beside its insulin-sensitizing action. The present review was aimed at describing all evidence-based and potential uses of metformin in PCOS patients. In particular, we will analyze the uses of metformin not only for the treatment of all PCOS-related disturbances such as menstrual disorders, anovulatory infertility, increased abortion, or complicated pregnancy risk, hyperandrogenism, endometrial, metabolic and cardiovascular abnormalities, but also for the prevention of the syndrome.