Gene expression in obese patients with non-alcoholic steatohepatitis]

Although the molecular basis for the pathophysiology of non-alcoholic steatohepatitis (NASH) is poorly understood, we evaluate the hepatic gene expression of cytokines, chemokines, cell receptors, growth factors, intracellular transducers and extracellular communication proteins in liver tissue of obese patients (with and without NASH), and we determine the specific intrahepatic gene expression profiles associated with histological severe NASH.Thirty-eight obese patients with BMI > 35 were analyzed, who underwent bariatric surgery. Biopsy specimen samples were snap-frozen in liquid nitrogen. Hepatic gene expression was determined in liver biopsy specimens from 3 groups: a) obese patients without NASH (n = 12); b) patients with NASH without fibrosis (n = 13); and c) patients with NASH and fibrosis (n = 13). Genes were considered to be expressed differentially in NASH only if there was a greater than 2-fold difference in abundance of mRNA when compared with each of the control group. These results were confirmed by real-time PCR. Fourteen genes were differentially expressed (10 overexpressed and 4 underexpressed) in patients with NASH. Genes that were significantly overexpressed included prohibitin, TNF, TNF RI (p55), MCSF, R2-TRAIL, b1-CTGF, FGF, VEGF, and BIGH3OBR. Insulin growth factor-1, insulin growth factor-2, interleukin-2 and tyrosine-receptor were underexpressed in NASH patients.In conclusion:1. The obese patients with NASH without fibrosis show an overexpression of proinflammatory and proapoptotic genes. Also, the NASH patients with fibrosis show an overexpression of fibrogenic genes, including the leptin receptor Ob-Rb.2. The up-regulated gene expression of prohibitin suggests mitochondrial dysfunction in NASH patients.     

Nonalcoholic steatohepatitis: association of insulin resistance and mitochondrial abnormalities

BACKGROUND AND AIMS: The pathogenesis of nonalcoholic steatohepatitis (NASH) is unknown. We tested the hypothesis that NASH is associated with 2 defects: (1) peripheral insulin resistance, which increases lipolysis, delivery of free fatty acids (FFA) to the liver, and hepatic fatty acid beta oxidation, thereby creating oxidative stress; and (2) an abnormality within the hepatocytes that might render them more susceptible to injury from oxidative stress. METHODS: The hypothesis was tested by evaluation of (1) insulin resistance by a 2-step hyperinsulinemic (10 and 40 mU. m(-2). min(-1)) euglycemic clamp; (2) insulin effects on lipolysis by enrichment of [U-(13)C]glycerol; (3) frequency and severity of structural defects in hepatocyte mitochondria in vivo; (4) fatty acid beta oxidation from serum [beta-OH butyrate], release of water-soluble radioactivity from (3)H-palmitate by cultured fibroblasts and urinary dicarboxylic acid excretion; and (5) hepatic lipid peroxidation by immunohistochemical staining for 3-nitrotyrosine (3-NT). Subjects with NASH (n = 6-10 for different studies) were compared with those with fatty liver (n = 6) or normal controls (n = 6). RESULTS: NASH and fatty liver were both associated with insulin resistance, with mean glucose infusion rates (normal/fatty liver/NASH) of step 1, 4.5/1.6/0.9; step 2, 9.5/7.7/4.5 (P < 0.03 for both steps). Although baseline rates of glycerol appearance were higher in those with NASH than in those with fatty liver (means, 14.6 vs. 21.6 micromol. kg(-1). min(-1); P < 0.05), neither group significantly suppressed glycerol appearance at insulin infusion rates of 10 mU. m(-2). min(-1). NASH was associated with loss of mitochondrial cristae and paracrystalline inclusions in 9 of 10 subjects, compared with 0 of 6 subjects with fatty liver. However, no evidence of a generalized defect in fatty acid beta oxidation was noted in any group. Also, mean [beta-OH butyrate] was highest in those with NASH (means, 90 vs. 110 vs. 160 micromol/L; P < 0.04). Increased staining for 3-NT was present in fatty liver, and even greater staining was seen in NASH. CONCLUSIONS: These data indicate that peripheral insulin resistance, increased fatty acid beta oxidation, and hepatic oxidative stress are present in both fatty liver and NASH, but NASH alone is associated with mitochondrial structural defects.     

Lower gut microbiome diversity and higher abundance of proinflammatory genus Collinsella are associated with biopsy-proven nonalcoholic steatohepatitis

ABSTRACT

There is increasing evidence for the role of gut microbial composition in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Nonalcoholic steatohepatitis (NASH) is the most serious form of NAFLD where inflammation causes liver damage that can progress to cirrhosis. We have characterized the gut microbiome composition in UK patients with biopsy-proven NASH (n = 65) and compared it to that in healthy controls (n = 76). We report a 7% lower Shannon alpha diversity in NASH patients without cirrhosis (n = 40) compared to controls (p = 2.7x 10^?4) and a 14% drop in NASH patients with cirrhosis (n = 25, p = 5.0x 10^?4). Beta diversity (Unweighted UniFrac distance) was also significantly reduced in both NASH (p = 5.6x 10^?25) and NASH-cirrhosis (p = 8.1x 10^?7) groups. The genus most strongly associated with NASH in this study was Collinsella (0.29% abundance in controls, 3.45% in NASH without cirrhosis (False Discovery Rate (FDR) p = .008), and 4.38% in NASH with cirrhosis (FDR p = .02)). This genus, which has been linked previously to obesity and atherosclerosis, was also positively correlated with fasting levels of triglycerides (p = .01) and total cholesterol (p = 1.2x 10^?4) and negatively correlated with high-density lipoprotein cholesterol (p = 2.8x 10^?6) suggesting that some of the pathways present in this microbial genus may influence lipid metabolism in the host. In patients, we also found decreased abundance of some of the Ruminococcaceae which are known to produce high levels of short-chain fatty acids which can lower inflammation. This may thus contribute to pathology associated with NASH.     

Pathophysiology of nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) affects approximately 30% of adults and 20% of children in the United States. Nonalcoholic steatohepatitis (NASH) is its most severe histologic form and progresses to cirrhosis in 20% of these patients. Once developed, 30% to 40% of patients with NASH cirrhosis will experience a liver-related death. Consequently, it has become extremely important to understand the pathophysiology of NASH to develop sound therapeutic interventions. It is now recognized that nonhepatic mechanisms are largely responsible for the development of insulin resistance, which causes hepatic steatosis. Once developed, oxidative stress and diminished antioxidants within the liver initiate the progression from steatosis alone to NASH and ultimately to cirrhosis. However, not all patients progress to cirrhosis. As is the case for other common complex metabolic diseases, it is the interaction between the environment and genetics that will determine the phenotypic expression of NAFLD and NASH in each individual patient. Which of the pathophysiologic factors (which are discussed in this review), either alone or in combination, will eventually provide the basis for the most effective therapy has yet to be determined.     

Nonalcoholic steatohepatitis: summary of an AASLD Single Topic Conference

Fatty liver disease that develops in the absence of alcohol abuse is recognized increasingly as a major health burden. This report summarizes the presentations and discussions at a Single Topic Conference held September 20-22, 2002, and sponsored by the American Association for the Study of Liver Diseases. The conference focused on fatty liver disorders. Estimates based on imaging and autopsy studies suggest that about 20% to 30% of adults in the United States and other Western countries have excess fat accumulation in the liver. About 10% of these individuals, or fully 2% to 3% of adults, are estimated to meet current diagnostic criteria for nonalcoholic steatohepatitis (NASH). Sustained liver injury leads to progressive fibrosis and cirrhosis in a fraction, possibly up to one third, of those with NASH, and NASH may be a cause of cryptogenic cirrhosis. NASH is now a significant health issue for obese children as well, leading to cirrhosis in some. The diagnostic criteria for NASH continue to evolve and rely on the histologic findings of steatosis, hepatocellular injury (ballooning, Mallory bodies), and the pattern of fibrosis. Generally recognized indications for biopsy include establishing the diagnosis and staging of the injury, but strict guidelines do not exist. Liver enzymes are insensitive and cannot be used reliably to confirm the diagnosis or stage the extent of fibrosis. Older age, obesity, and diabetes are predictive of fibrosis. The pathogenesis of NASH is multifactorial. Insulin resistance may be an important factor in the accumulation of hepatocellular fat, whereas excess intracellular fatty acids, oxidant stress, adenosine triphosphate (ATP) depletion, and mitochondrial dysfunction may be important causes of hepatocellular injury in the steatotic liver. Efforts are underway to refine the role of insulin resistance in NASH and determine whether improving insulin sensitivity pharmacologically is an effective treatment. An altered lifestyle may be a more effective means of improving insulin sensitivity. The research agenda for the future includes establishing the role of insulin resistance and abnormal lipoprotein metabolism in NASH, determining the pathogenesis of cellular injury, defining predisposing genetic abnormalities, identifying better noninvasive predictors of disease, and defining effective therapy.     

Prevalence of esophagogastric varices in patients with non-alcoholic steatohepatitis.

Aim: In non-alcoholic steatohepatitis (NASH), fibrosis begins around the central veins, as also happens with alcoholic liver disease, so the symptoms of portal hypertension may be due to central vein occlusion. The aim of this study was to define the prevalence of esophagogastric varices and the clinical outcome after endoscopic treatment in NASH patients with severe fibrosis. Methods: The subjects were 72 patients with clinicopathologically confirmed NASH who had bridging fibrosis (F3) or cirrhosis (F4) determined by the examination of liver biopsy specimens, and who underwent upper gastrointestinal endoscopy. The prevalence and pattern of endoscopically detected varices at the time of liver biopsy were evaluated. The results of NASH patients (n = 11) with endoscopically treated esophageal varices were compared to those with alcoholic (n = 67) and hepatitis C virus-associated cirrhosis (n = 152). Results: Esophagogastric varices were detected in 34 out of the 72 (47.2%) patients; esophageal varices in 25 (34.7%) and gastric varices in nine (12.5%), while six of these patients had variceal bleeding. In NASH patients, the cumulative recurrence-free probability at 24 months after endoscopic treatment was 63.6%, the bleeding-free probability was 90.9%, and the 5-year survival was 100%. Only one out 11 patients died of liver failure at 70 months after treatment. Conclusion: About half of NASH patients with severe fibrosis had esophagogastric varices. The clinical status and course of the varices do not necessarily improve after endoscopic treatment. NASH patients with esophagogastric varices need to be followed up carefully, like patients with other chronic liver diseases.     

Nonalcoholic steatohepatitis and the metabolic syndrome

Relatively recently, the liver has been recognized as a major target of injury in patients with insulin resistance or the metabolic syndrome. Insulin resistance is associated with fat accumulation in the liver, a condition called nonalcoholic fatty liver disease (NAFLD). Excess fat in the liver is not a benign condition. Some patients with NAFLD develop necroinflammatory changes in the liver called nonalcoholic steatohepatitis (NASH) and a fraction of those will develop cirrhosis. About 20% all adults have NAFLD and 2% to 3% of adults have NASH. Approximately 20% of patients with NASH are at risk for developing cirrhosis and subsequently dying from end-stage liver disease. The diagnosis of NASH requires a high index of suspicion, especially in obese patients over the age of 45 years who have diabetes, because these are the patients at greatest risk for developing cirrhosis. Treatment focuses on addressing the underlying insulin resistance with increased exercise and weight reduction.     

Nonalcoholic steatohepatitis in Asian Indians is neither associated with iron overload nor with HFE gene mutations

AIM: The pathogenesis of occurrence of liver inflammation and fibrosis in patients with nonalcoholic steatohepatitis (NASH) is not completely understood. Other than insulin resistance, iron abnormalities have been thought to be one of the triggering factors. Therefore, our aim was to study the role of iron abnormalities and HFE gene mutations in patients with NASH. METHODS: Thirty-one patients of NASH diagnosed on the basis of clinical examination biochemistry, ultrasonography and liver biopsy (n = 14) were included in the study. Serum iron parameters (n = 23) (iron, ferritin, total iron-binding capacity and transferrin saturation), Perls' iron staining on liver biopsies (n = 14) and HFE gene mutations (C282Y and H63D) (n = 16) were studied in these patients. The association between iron staining, necroinflammatory activity and fibrosis stage on liver biopsies was also determined. RESULTS: Elevated serum iron, ferritin and transferrin saturation above 55% were observed in 4.3% of patients. On histology, 71% of the patients had negative iron staining, 21.4% had 1+ staining, 7.2% had 2+ staining and none had 3+ or 4+ staining. There was no association between the degree of iron staining and necroinflammatory activity (P=0.55) and fibrosis stage (P= 0.09) on histology. None of the patients had C282Y HFE gene mutation and four patients (25%) were found to be heterozygotes for H63D gene mutation. CONCLUSION: Our study does not favor iron overload and HFE gene mutations as major factors in the pathogenesis of NASH in Asian Indians.     

Does leptin play a role in the pathogenesis of human nonalcoholic steatohepatitis?

OBJECTIVES: Obesity is a risk factor for nonalcoholic steatohepatitis (NASH). Leptin plays an important role in the regulation of food intake, body composition, energy expenditure, and body weight. It has been suggested that leptin plays a role in the pathogenesis of NASH; however, adequate studies are lacking. We therefore conducted a study to explore the role of serum leptin in the pathogenesis of human NASH. METHODS: We measured the levels of serum leptin and its anthropometric, biochemical, metabolic, and histological correlates in a cohort of patients with NASH (n = 26) and well-matched controls (n = 20). Furthermore, we measured the levels of leptin in the serum and hepatic leptin and leptin receptor messenger RNA (mRNA) expression in liver biopsy specimens of patients with NASH (n = 5) and simple steatosis (n = 5). RESULTS: Serum leptin was not statistically different between patients with NASH and their controls (21 +/- 13 vs 18 +/- 11 ng/ml, respectively, p = 0.5). There was no correlation between serum leptin and hepatic histology, serum transaminases, fasting insulin levels, or a measure of insulin resistance. After adjusting for covariates in a multiple regression analysis, only percent body fat (p = 0.04) and subcutaneous abdominal fat area (p = 0.04) had significant correlation with serum leptin. There was no expression of leptin mRNA in the cell lysate of liver biopsy specimens of subjects with NASH or steatosis. Additionally, the serum leptin levels and the hepatic leptin receptor mRNA expression were not statistically different between patients with NASH and those with simple steatosis. CONCLUSION: These data do not support a direct role for leptin in the pathogenesis of human NASH.     

Pathogenesis of nonalcoholic steatohepatitis (NASH)

Nonalcoholic fatty liver disease (NAFLD) represents a spectrum of liver diseases that range from hepatic steatosis at the most clinically benign end of the spectrum, through an intermediate lesion, nonalcoholic steatohepatitis (NASH), to cirrhosis at the opposite extreme. Epidemiology studies have estimated that about 20-30% of adults in the United States and other Western countries have NAFLD, and of these about 10% (2-3% of adults) meet the diagnostic criteria of NASH. Studies of animals and humans with obesity-related fatty liver disease have revealed much about the mechanisms that mediate this common pathology. The pathogenesis of NASH is multifactorial and includes insulin resistance, excessive intracellular fatty acids, oxidant stress, mitochondrial dysfunction and the role of innate immunity. This review will briefly discuss the epidemiology of NAFLD and focus on current understanding of the pathogenesis of NASH.     

Noninvasive laboratory tests proposed for predicting cirrhosis in patients with chronic hepatitis C are also useful in patients with non-alcoholic steatohepatitis

Background  Several noninvasive tests have been proposed to predict cirrhosis in patients with chronic hepatitis C, but not in patients with non-alcoholic steatohepatitis (NASH). We assessed whether noninvasive laboratory tests designed to predict the risk of cirrhosis in patients with chronic hepatitis C virus (HCV) infection could be used in patients with NASH. Methods  The subjects were 50 patients with biopsy-proved NASH and 100 age- and sex-matched patients with HCV. Aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio (AAR), age-platelet (AP) index, AST-to-platelet ratio index (APRI), cirrhosis discriminant score (CDS), and the hepatitis C antiviral long-term treatment against cirrhosis (HALT-C) model were calculated. Results  The areas under the receiver-operating characteristic curves of the AAR, AP index, APRI, CDS, and HALT-C model for predicting cirrhosis were respectively 0.813, 0.877, 0.786, 0.949, and 0.908 in patients with NASH and 0.555, 0.652, 0.761, 0.782, and 0.782 in patients with HCV. A CDS cutoff value of less than 5 misclassified none of the 9 patients with NASH who had cirrhosis, while a value of more than 8 misclassified none of the 41 patients with NASH without cirrhosis. With the HALT-C model, a cutoff value of less than 0.6 classified non-cirrhotic NASH, while a cutoff value of 0.97 or higher classified cirrhotic NASH. The use of CDS and HALT-C model could avoid liver biopsy for predicting cirrhosis in 60 and 48% of the patients with NASH, respectively. Conclusions  Noninvasive laboratory tests designed to predict cirrhosis in patients with HCV are also useful in patients with NASH.     

Drugs and steatohepatitis

In addition to the usual associations with insulin resistance, type 2 diabetes, central obesity, and hypertriglyceridemia, nonalcoholic steatohepatitis (NASH) has been associated with several drugs and toxins. However, drug-induced liver disease is a relatively uncommon cause of steatohepatitis. The term drug-induced steatohepatitis is preferred when the association appears to result from a direct toxic effect of the drug on the liver. For some agents implicated as causing cirrhosis or fatty liver disorders, the association may be coincidental because NASH is a common component of the insulin resistance (or metabolic) syndrome. In other instances, corticosteroids, tamoxifen, and estrogens may precipitate NASH in predisposed persons by exacerbating insulin resistance, central obesity, diabetes, and hypertriglyceridemia, and methotrexate may worsen hepatic fibrosis in NASH. Drug-induced steatohepatitis is associated with prolonged therapy (more than 6 months) and possibly drug accumulation, which in the case of perhexiline maleate is favored by a genetic polymorphism of CYP2D6 that leads to slow perhexiline oxidation. The toxic mechanism appears to involve mitochondrial injury, which causes steatosis because of impaired beta-oxidation of fatty acids, and leads to generation of reactive oxygen species and ATP depletion. Thus, drug-induced steatohepatitis may provide clues to injurious events in the more common metabolic forms of NASH. A clinical feature of some types of drug-induced steatohepatitis is progression after discontinuation of the causative agent. It follows that early recognition of hepatotoxicity is crucial to prevent the development of severer forms of liver disease and improve the clinical outcome.     

Nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is an underdiagnosed liver disease characterised by steatosis, necroinflammation and fibrosis. This disease may eventually develop into cirrhosis and hepatocellular carcinoma. NASH is highly prevalent among obese individuals and among patients with diabetes mellitus type 2. Nonalcoholic fatty liver (NAFL), a precursor of NASH, is the main cause of elevated serum liver enzymes among the general population. Insulin resistance is a major aetiological factor in NASH. Gradual weight loss, physical exercise and drugs that improve insulin sensitivity are potential therapies.     

Prevalence of metabolic syndrome in non-diabetic and non-cirrhotic patients with non-alcoholic steatohepatitis.

Recently, insulin resistance (IR) was proposed as a primary pathogenic mechanism in non-alcoholic steatohepatitis (NASH). The prevalence of IR and metabolic syndrome remains largely unstudied in patients with NASH and without diabetes and cirrhosis, both being conditions associated with IR. During a 1-year period, all non-diabetic and noncirrhotic patients seen in our institute with a diagnosis of NASH were subjected to anthropometric measurements, clinical examination, lipid profile and glucose tolerance test to define metabolic syndrome. All the patients underwent test for fasting glucose and insulin levels to define the insulin resistance by HOMA-R (homeostasis model assessment) method. Of the 25 patients with NASH, the metabolic syndrome was present in 17 (68%) and at least one criterion for the metabolic syndrome was present in all the patients. IR was present in 20 patients (80%). All the patients were either overweight (8%) or obese (92%). Because of the high prevalence of the metabolic syndrome and IR in patients with NASH, it is pertinent to test for IR and metabolic abnormalities in all patients with NASH. Also, all patients with metabolic syndrome should undergo liver function tests and, in the presence of abnormal transaminases, a liver biopsy to define NASH.     

Primary liver cancers with nonalcoholic steatohepatitis

Nine patients with hepatocellular carcinoma (HCC) in nonalcoholic steatohepatitis (NASH) (six men and three women, median age 71.5 years) and one patient with intrahepatic cholangiocarcinoma (ICC), a 50-year-old man, in NASH are described. Most patients were associated with obesity, diabetes, hypertension, hypercholesterolemia, or hypertriglyceridemia. Seven patients showed insulin resistance and hyperinsulinemia. All patients except one met the criteria for metabolic syndrome. An HCC or ICC diagnosis was confirmed by tumor biopsy, surgery or autopsy except in two patients, who were diagnosed by computed tomography or hepatic angiography. The underlying liver disease was liver cirrhosis in six patients and chronic liver disease including mild hepatic fibrosis in four patients. The treatment of liver cancers consisted of surgery, radio-frequency ablation (RFA), transcatheter arterial embolization and transcatheter arterial infusion. Although the follow-up period was relatively short (median 27.5 months, average 32.1 months), all postoperative and post-RFA patients have not had a recurrence of HCC to date, except for one patient who had a palliative operation with intra-arterial infusion of anticancer drugs through an implanted reservoir port. Older age and liver cirrhosis are considered risk factors for HCC in NASH, and regular screening of these patients is necessary. Diabetes may contribute to the development of ICC in NASH. Curative therapy (surgery or RFA) and weight loss by the active therapeutic intervention (nutritional care and exercise therapy) after curative therapy may help us improve the prognosis of HCC in NASH.     

Leptin levels in nonalcoholic steatohepatitis and chronic hepatitis C.

BACKGROUND/AIMS: Leptin is a peptide which regulates food intake and energy expenditure. Moreover, it is involved in the homeostasis of body composition and is linked to the regulation of insulin signaling, thus playing an important role in liver fat storage. Steatosis is a common finding in chronic hepatitis C, and both viral and metabolic factors have been suggested to explain the presence of this histological characteristic. In order to study leptin in chronic liver disease characterized by the presence of steatosis, we evaluated its serum levels in patients with nonalcoholic steatohepatitis (NASH), in chronic hepatitis C (CHC) patients with no histological findings of steatosis, and CHC patients with steatosis but no risk factors for its development. METHODOLOGY: We studied 6 male patients with NASH whose diagnosis was made on the basis of histological findings and clinical criteria. From among a cohort of 170 CHC patients we put together 2 groups of 6 male patients each (with or without steatosis at liver biopsy examination), who had no risk factors for NASH. Male patients were chosen in order to avoid gender influence on leptin levels. Further criteria for admission were similar impairment of liver metabolic function as assessed by the monoethylglycinexylidide (MEGX) test and, in patients with CHC, similar body mass index (BMI) and histological staging. Moreover, we evaluated leptin/BMI ratio, in order to rule out BMI influence on leptin levels. Leptin levels were assessed by means of radioimmunoassay. RESULTS: We found that BMI was higher in NASH compared to CHC (27.2 +/- 2.9 vs. 23.9 +/- 1.8; p = 0.01). Analysis of serum leptin levels showed an increasing trend starting from patients with CHC without steatosis (3.2 +/- 0.4 ng/ml), through CHC patients with steatosis (4.2 +/- 0.7 ng/ml) up to patients with NASH (5.7 +/- 2 ng/ml), although the differences observed were not statistically significant. Moreover, the ratio of leptin to BMI also followed the same trend showing increasing values (CHC without steatosis = 0.04 +/- 0.02; CHC patients with steatosis = 0.17 +/- 0.03; NASH = 0.203 +/- 0.07). Leptin levels and BMI showed a significant relationship (n = 18; r = 0.60; p < 0.01). CONCLUSIONS: The increasing trend observed in leptin serum levels among the different groups of patients showed that in chronic liver disease characterized by the presence of steatosis, leptin signaling is preserved. Moreover, CHC factors different from the metabolic ones should be investigated in order to explain the presence of steatosis. Further studies on broader groups of patients are needed to verify these preliminary results.     

Non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is an underdiagnosed liver disease characterized by steatosis, necroinflammation and fibrosis. This disease may eventually develop into cirrhosis and hepatocellular carcinoma. NASH is highly prevalent among obese individuals and among patients with diabetes mellitus type 2. Non-alcoholic fatty liver (NAFL), a precursor of NASH, is the main cause of elevated serum liver enzymes among the general population. In NASH the liver is programmed to lipogenesis rather than to glycogenesis and herein insulin-resistance plays a major role. Gradual weight loss, physical exercise and drugs that improve insulin sensitivity are potential therapies.