Mitochondrial abnormality and oxidative stress in nonalcoholic steatohepatitis.

BACKGROUND: Oxidative stress plays a major role in the pathogenesis of nonalcoholic steatohepatitis (NASH). Mitochondrial abnormality may be associated with the onset and progression of NASH via excessive formation of mitochondrial reactive oxygen species. This study aimed to investigate the role of mitochondrial abnormality in NASH in relation to oxidative stress. METHODS: Twenty-six patients with NASH, 11 with simple steatosis, and 10 healthy volunteers underwent clinico-pathological analysis. The liver/spleen ratio, an index of the hepatic fat content, was evaluated with computed tomography. Plasma glutathione levels were measured as an antioxidative marker, and the urinary 8-isoprostane levels and 3-nitrotyrosine staining in the liver as an oxidative stress marker. Mitochondrial abnormality was estimated by serum levels of mitochondria aspartate transaminase (mAST) and the mitochondrial staining in the liver. RESULTS: Urinary 8-isoprostane levels were higher in NASH than in the healthy volunteers, whereas plasma glutathione levels were similar in the 2 groups. In NASH, urinary 8-isoprostane levels positively correlated with alanine transaminase levels and negatively with the liver/spleen ratio. The 3-nitrotyrosine staining was more advanced in simple steatosis and NASH than in the normal liver, but was similar in simple steatosis and NASH. In contrast to the normal mAST levels in the healthy volunteers and simple steatosis, serum mAST levels were elevated in one-fourth of the NASH patients and positively correlated with urinary 8-isoprostane levels in NASH. Most cases of NASH showed diffuse or focal but intense mitochondrial staining in the liver in contrast to scattered staining in simple steatosis. CONCLUSIONS: Our present study demonstrated that in NASH, the enhanced oxidative stress may be associated with hepatic inflammation and the degree of fat infiltration in the liver. However, simple steatosis and NASH were both exposed to oxidative stress, while NASH alone was associated with mitochondrial abnormality. These findings indicate that mitochondrial abnormality may play a role in the onset and progression of NASH in correlation with oxidative stress.

Cryptogenic cirrhosis in the region where obesity is not prevalent.

AIM: Recent studies have demonstrated that obesity is the common feature of cryptogenic cirrhosis (CC) and non-alcoholic steatohepatitis. However, there is little information on CC in the region where obesity is not prevalent. METHODS: The clinical features, and the liver-related morbidity and mortality of CC were analyzed in Japan where the prevalence of obesity is low. Among 652 cirrhotic patients, we identified 29 patients (4.4%) with CC. Of these, 24 CC patients who were followed up for more than 6 months were compared in a case-control study with age-, sex-, and Child-Pugh score-matched controls having cirrhosis of viral etiology. RESULTS: Obesity (BMI>or=25 kg/m(2)), diabetes mellitus, and hypertriglyceridemia were more frequent, and the visceral fat area was larger in the CC patients than in the controls. The indices of insulin resistance were higher and the serum aminotransferase levels were lower in the CC patients than in the controls. Logistic regression analysis identified the elevated hemoglobin A1c, BMI>or=25 kg/m(2), and normal aminotransferase levels as independent predictors of CC. Kaplan-Meier analysis demonstrated lower occurrence of hepatocellular carcinoma and higher survival rate in the CC than in the controls in contrast to the similar cumulative probability of liver-related morbidity between those groups. CONCLUSION: CC more frequently presents with the clinical features suggestive of non-alcoholic steatohepatitis compared with controls even in the region where obesity is not prevalent. The lower occurrence of hepatocellular carcinoma and higher survival rate may indicate an indolent clinical course in CC as compared with viral cirrhosis.

Difference and similarity between non-alcoholic steatohepatitis and alcoholic liver disease.

BACKGROUND: Non-alcoholic steatohepatitis (NASH) and alcoholic liver disease (ALD) are extremely similar in the pathologic findings and pathogenesis. This study aimed to elucidate the difference and similarity between these diseases. METHODS: Twenty-six patients with NASH and 26 with ALD including 11 with alcoholic hepatitis underwent clinico-pathologic analysis. The visceral fat area and liver/spleen ratio, an index of the hepatic fat content, were evaluated with computed tomography. The hepatic iron deposit and oxidative stress induced-lipid peroxidation were estimated by Prussian blue staining and 3-nitrotyrosine staining, respectively. RESULTS: The most prominent difference between NASH and ALD was the nutritional status, although elevation of AST/ALT ratio and gamma-GT is relatively characteristic of ALD. NASH was more frequently associated with diabetes mellitus as compared with ALD. The BMI and serum levels of total cholesterol and cholinesterase were higher in NASH than in ALD. Although the degree and distribution of fibrosis and necro-inflammatory reaction were similar in NASH and ALD, steatosis was more severe in NASH than in ALD. The liver/spleen ratio was lower and the visceral fat area was larger in NASH than in ALD, regardless of the coincidence of alcoholic hepatitis. Interestingly, the visceral fat area positively correlated with ALT and HOMA-IR in NASH, whereas these correlations were not observed in ALD. The hepatic iron deposit was less in NASH than in ALD, whereas lipid peroxidation in NASH was similar to that in ALD with alcoholic hepatitis and more advanced as compared with that in ALD without alcoholic hepatitis. CONCLUSIONS: NASH was characterized with over-nutrition and visceral fat type obesity as compared with ALD. The visceral fat accumulation was associated with hepatic inflammation and insulin resistance in NASH, but not in ALD. The difference in the nutritional status between NASH and ALD is not only reflected in the clinical features but also may closely associate with the mechanisms of hepatocellular damage in these diseases.