Nonalcoholic steatohepatitis (NASH) is a common chronic liver disease for which there is no known effective therapy. A proportion of patients with NASH progress to advanced fibrosis and cirrhosis. NASH is considered one of the clinical features of the metabolic syndrome in which insulin resistance plays a central role. This prospective study evaluates the role of insulin-sensitizing agent in treatment of NASH. Eighteen nondiabetic patients with biopsyproven NASH were treated with pioglitazone (30 mg daily) for 48 weeks. Tests of insulin sensitivity and body composition as well as liver biopsies were performed before and at the end of treatment. By 48 weeks, serum alanine aminotransferase values fell to normal in 72% of patients. Hepatic fat content and size as determined by magnetic resonance imaging decreased, and glucose and free fatty acid sensitivity to insulin were uniformly improved. Histological features of steatosis, cellular injury, parenchymal inflammation, Mallory bodies, and fibrosis were significantly improved from baseline (all P < 0.05). Using strict criteria, histological improvement occurred in two-thirds of patients. Pioglitazone was well tolerated; the main side effects were weight gain (averaging 4%) and an increase in total body adiposity. In conclusion, these results indicate that treatment with an insulin-sensitizing agent can lead to improvement in biochemical and histological features of NASH and support the role of insulin resistance in the pathogenesis of this disease. The long-term safety and benefits of pioglitazone require further study. (HEPATOLOGY 2004;39:188 -196.)

Genome-wide association studies identified single-nucleotide polymorphisms (SNPs) that are associated with increased hepatic fat or elevated liver enzymes, presumably reflecting nonalcoholic fatty liver disease (NAFLD). To investigate whether these SNPs are associated with histological severity of NAFLD, 1117 (894 adults/223 children) individuals enrolled in the Nonalcoholic Steatohepatitis (NASH) Clinical Research Network and National Institutes of Health Clinical Center studies with histologically confirmed NAFLD were genotyped for six SNPs that are associated with hepatic fat or liver enzymes in genome-wide association studies. In adults, three SNPs on chromosome 22 showed associations with histological parameters of NASH. After adjustment for age, sex, diabetes, and alcohol consumption, the minor allele of rs738409 C/G, a nonsynonymous coding SNP in the patatin-like phospholipase domain-containing protein 3 (PNPLA3) (adiponutrin) gene encoding an Ile148Met change, was associated with steatosis ( P = 0.03), portal inflammation ( P = 2.5 × 10−4), lobular inflammation ( P = 0.005), Mallory-Denk bodies ( P = 0.015), NAFLD activity score (NAS, P = 0.004), and fibrosis ( P = 7.7 × 10−6). Two other SNPs in the same region demonstrated similar associations. Three SNPs on chromosome 10 near the CHUK (conserved helix-loop-helix ubiquitous kinase) gene were independently associated with fibrosis ( P = 0.010). In children, no SNP was associated with histological severity. However, the rs738409 G allele was associated with younger age at the time of biopsy in multivariate analysis ( P = 0.045). Conclusion: In this large cohort of histologically proven NAFLD, we confirm the association of the rs738409 G allele with steatosis and describe its association with histological severity. In pediatric patients, the high-risk rs738409 G allele is associated with an earlier presentation of disease. We also describe a hitherto unknown association between SNPs at a chromosome 10 locus and the severity of NASH fibrosis.

Nonalcoholic fatty liver disease (NAFLD) is a common cause of chronic liver disease. A single‐nucleotide polymorphism (SNP), rs6834314, was associated with serum liver enzymes in the general population, presumably reflecting liver fat or injury. We studied rs6834314 and its nearest gene, 17‐beta hydroxysteroid dehydrogenase 13 (HSD17B13), to identify associations with histological features of NAFLD and to characterize the functional role of HSD17B13 in NAFLD pathogenesis. The minor allele of rs6834314 was significantly associated with increased steatosis but decreased inflammation, ballooning, Mallory‐Denk bodies, and liver enzyme levels in 768 adult Caucasians with biopsy‐proven NAFLD and with cirrhosis in the general population. We found two plausible causative variants in the HSD17B13 gene. rs72613567, a splice‐site SNP in high linkage with rs6834314 (r2 = 0.94) generates splice variants and shows a similar pattern of association with NAFLD histology. Its minor allele generates simultaneous expression of exon 6‐skipping and G‐nucleotide insertion variants. Another SNP, rs62305723 (encoding a P260S mutation), is significantly associated with decreased ballooning and inflammation. Hepatic expression of HSD17B13 is 5.9‐fold higher (P = 0.003) in patients with NAFLD. HSD17B13 is targeted to lipid droplets, requiring the conserved amino acid 22‐28 sequence and amino acid 71‐106 region. The protein has retinol dehydrogenase (RDH) activity, with enzymatic activity dependent on lipid droplet targeting and cofactor binding site. The exon 6 deletion, G insertion, and naturally occurring P260S mutation all confer loss of enzymatic activity. Conclusion: We demonstrate the association of variants in HSD17B13 with specific features of NAFLD histology and identify the enzyme as a lipid droplet–associated RDH; our data suggest that HSD17B13 plays a role in NAFLD through its enzymatic activity.

A pilot study of a 48-week course of pioglitazone demonstrated significant improvements in the biochemical and histological features of nonalcoholic steatohepatitis (NASH). The aim of the study was to assess the effects of stopping pioglitazone. Twenty-one patients with NASH were treated with pioglitazone (30 mg/day) for 48 weeks and underwent baseline and end-of-treatment evaluation including liver biopsy. Thirteen patients were followed for at least 48 weeks after stopping therapy and 9 underwent repeat liver biopsy. Statistical comparisons were made to evaluate whether discontinuation of pioglitazone resulted in a reversal of improvements seen on therapy. Stopping pioglitazone was associated with subsequent elevation in serum alanine aminotransferase levels (from 34 ؎ 13 to 70 ؎ 39 IU/l), decrease in adiponectin (from 9.7 ؎ 9.1 to 5.1 ؎ 4.5 g/ml), worsening insulin sensitivity (HOMA Index: from 2.9 ؎ 1.8 to 5.5 ؎ 5.4), and increase in total hepatic fat (from 30% ؎ 32% to 71% ؎ 33%) despite no change in average body weight compared to the end of treatment. Repeat liver biopsy in 9 patients revealed significant worsening of parenchymal inflammation (from 1.2 ؎ 0.7 to 2.9 ؎ 1.1) and steatosis (from 0.9 ؎ 0.6 to 2.1 ؎ 1.3) but no change in fibrosis (from 1.1 ؎ 1.2 to 1.2 ؎ 1.3). NASH was again present on liver biopsy in 7 patients. Conclusion: These findings suggest that long-term therapy with pioglitazone may be necessary to maintain improvements in disease activity in patients with NASH, although weight gain during treatment may ultimately limit its beneficial effects. (HEPATOLOGY 2007;46: 424-429.)See Editorial on Page 285 N onalcoholic steatohepatitis (NASH) is an inflammatory liver disease associated with progressive liver injury which can eventually lead to cirrhosis, end-stage liver disease, and hepatocellular carcinoma. 1 The etiology of NASH is thought to be related to insulin resistance and the metabolic syndrome. 2 NASH is closely associated with obesity and thus may represent the most prevalent chronic liver disease in the United States. 3,4 Several strategies aimed at improving insulin resistance have been employed in clinical trials for NASH, one being controlled weight loss using diet and exercise. This approach has had limited success in those patients who are able to lose and maintain weight loss in the long term. The improvement in histology with weight loss is primarily in hepatic steatosis rather than inflammation and fibrosis. [5][6][7] Thus far, pharmacological therapy aimed at weight loss has been disappointing, and histological data on the effects of weight-loss medications are lacking. 8 A more sustained option is bariatric surgery which has been shown to promote marked weight loss, decrease insulin resistance, and improve liver histology in patients with NASH. 9 However, for most patients with NASH, an invasive surgical procedure with major metabolic effects is not an appropriate option.Drug therapy primarily aimed at improving insulin resistance presents a possible option for patien...