脂肪性肝病：愈来愈严重的全球性公共卫生问题

脂肪性肝病分为酒精性肝病和非酒精性脂肪性肝病,其发病率呈逐年上升趋势,目前认为是终末期肝病的主要病因之一,正成为世界范围内威胁人类健康的重大问题。深入探讨其发病机制,揭示疾病特点,将有助于提高脂肪性肝病的诊治水平,从而改善人类健康、减少社会经济负担。     

Intestinal Dysbiosis: A Possible Mechanism of Alcohol-Induced Endotoxemia and Alcoholic Steatohepatitis in Rats

Background:  Clinical and animal data indicate that gut-derived endotoxin and other luminal bacterial products are necessary cofactors for development of alcoholic liver disease (ALD). Although gut leakiness is clearly an important cause of endotoxemia in ALD, it cannot fully explain endotoxemia in all ALD subjects and thus other factors may be involved. One possible factor is a change in gut microbiota composition (dysbiosis). Thus, the aim of our study was to interrogate the gut bacterial microbiota in alcohol-fed rats to see if chronic alcohol consumption affects gut bacteria composition.
Method:  Male Sprague–Dawley rats were given either alcohol or dextrose intragastrically by gavage twice daily for up to 10 weeks. A subgroup of rats was also given either a probiotic (lactobacillus GG) or a prebiotic (oats) by gavage. Ileal and colonic mucosal-attached microbiota composition were interrogated by Length Heterogeneity PCR (LH-PCR) fingerprinting.
Results:  Bacterial microbiota composition in alcohol-fed rats is not different from dextrose-fed rats at weeks 4 and 6. Mucosa-associated microbiota composition in the colon is altered at 10 weeks of daily alcohol gavage. Both LGG and oats prevented alcohol-induced dysbiosis up to 10 weeks of alcohol treatment.
Conclusion:  Daily alcohol consumption for 10 weeks alters colonic mucosa-associated bacterial microbiota composition in rats. Our data showed, for the first time, that daily alcohol consumption can affect colonic microbiome composition and suggest that dysbiosis may be an important mechanism of alcohol-induced endotoxemia. Further studies are needed to determine how dysbiotic microbiota contributes to development of ALD and whether therapeutic interventions targeted towards dysbiotic microbiota can prevent complications of alcoholism like ALD.     

Liver disease in heavy drinkers with and without alcohol withdrawal syndrome

BACKGROUND: Withdrawal syndrome is a hallmark of alcohol dependence. The characteristics of alcohol consumption, closely related to dependence, could influence the development of alcoholic liver disease. The study aimed to investigate if patients with severe alcohol withdrawal syndrome have a peculiar profile of liver disease. METHODS: The study included 256 heavy drinkers (aged 19-75 years, 70.3% males) admitted to an Internal Medicine Department. Patients admitted for complications of liver disease were not included. Severe alcohol withdrawal syndrome (seizures, disordered perceptions, or delirium) developed in 150 patients (58.6%). Alcohol consumption (daily quantity, duration, and pattern [regular or irregular]) was assessed by questionnaire. Liver biopsy was performed in all cases. RESULTS: Patients with alcohol withdrawal syndrome showed a lower prevalence of liver cirrhosis and a higher prevalence of alcoholic hepatitis than patients without it. The negative association of alcohol withdrawal syndrome with liver cirrhosis persisted after we adjusted for sex, daily intake, duration, and pattern of alcohol consumption. Alcoholic hepatitis was independently associated with the irregular pattern of alcohol consumption, which was closely associated with severe alcohol withdrawal syndrome. CONCLUSIONS: The profile of liver injury is different in heavy drinkers who develop and who do not develop a severe alcohol withdrawal syndrome when admitted to the hospital.     

Effect of Fenofibrate on Fatty Liver in Rats Treated With Alcohol

Background: Although fatty liver and hyperlipemia are common in chronic alcoholics, there is no practical approach to prevent alcoholic fatty liver. Recently, it has been reported that fibrates bind to peroxisome proliferator-activated receptor-α and induce β-oxidation enzymes of fatty acid in mitochondria. In this study, we investigated the effect of fenofibrate, one of the fibrates, on fatty liver in rats induced by chronic alcohol feeding. Furthermore, we studied the effect of fenofibrate on hyperlipemia in patients with alcoholic fatty liver.
Methods: Male Wistar rats were treated with liquid diet that contained ethanol (36% of total calories) or an isocaloric carbohydrate instead of ethanol for 4 weeks. Fenofibrate was administered orally with the liquid diets for 4 weeks at a concentration of either 0, 5, or 30 mg/kg body weight/day. As a pilot study, eight patients with alcoholic fatty liver were treated with 200 mg/day of fenofibrate for 4 weeks.
Results: After fenofibrate administration, fatty degeneration of liver was not observed in three of the five rats treated with 5 mg and in all rats treated with 30 mg of fenofibrate. Hepatic triglyceride content was decreased significantly in rats treated with 30 mg of fenofibrate compared with the rats not treated with fenofibrate. Serum triglyceride and total cholesterol levels also were decreased after treatment with fenofibrate. In eight alcoholic patients treated with 200 mg of fenofibrate for 4 weeks, serum triglyceride level decreased significantly compared with the levels before treatment. All patients continued alcohol consumption during fenofibrate administration.
Conclusion: The results of the present investigation suggest that fenofibrate may be useful to prevent alcoholic fatty liver. Further studies with larger numbers of patients are necessary to obtain definitive results.     

Alcohol Mediates Increases in Hepatic and Serum Nonheme Iron Stores in a Rat Model for Alcohol-Induced Liver Injury

The notion that prolonged ethanol consumption promotes hepatocellular damage through interactions with iron was evaluated in rats fed ethanol with or without supplemental dietary carbonyl iron. The individual and combined pro-oxidant potential of these agents was evaluated in terms of their ability to perturb iron homeostasis and initiate hepatocellular injury. Sprague-Dawely rats received a high fat liquid diet for 8 weeks supplemented with 35% ethanol-derived calories (Alcohol group), 0.02 to 0.04% (w/v) carbonyl iron (Iron group), ethanol plus carbonyl iron (Alcohol + Iron group), or a diet containing carbohydrate-derived isocaloric calories (Control group). Hepatic and serum nonheme iron stores were significantly elevated (p < 0.05) in all treatment groups, compared with the Controls. Catalytically active low-molecular weight iron was detected in rats consuming alcohol and was markedly elevated (p < 0.05) in rats ingesting iron alone or iron in combination with alcohol. Elevations in serum ALT indicated significant hepatocellular injury in rats ingesting only alcohol, but was most prominent in the rats consuming ethanol in combination with iron (p < 0.05). Significant hepatic fatty infiltration, increased hydroxyproline content, and perturbations in reduced glutathione were also observed in the Alcohol and Iron treatment groups. Histochemical assessment of hepatic iron sequestration revealed that alcohol feeding resulted in deposition of ferric iron in the centrilobular area of the liver lobule. This unique alcohol-mediated iron deposition was histologically graded above Control group and was observed in both hepatocytes and Kupffer cells. Data presented herein suggest that alcohol alone or in combination with iron results in rather specific lobular patterns of hepatic iron deposition relevant to iron overload observed in human alcoholics. Furthermore, data suggest that alcohol- and iron-initiated prefibrotic events occur before extensive hepatocellular necrosis.     

Nitric Oxide-Mediated Intestinal Injury Is Required for Alcohol-Induced Gut Leakiness and Liver Damage

Background: Alcoholic liver disease (ALD) requires endotoxemia and is commonly associated with intestinal barrier leakiness. Using monolayers of intestinal epithelial cells as an in vitro barrier model, we showed that ethanol‐induced intestinal barrier disruption is mediated by inducible nitric oxide synthase (iNOS) upregulation, nitric oxide (NO) overproduction, and oxidation/nitration of cytoskeletal proteins. We hypothesized that iNOS inhibitors [NG‐nitro‐l ‐arginine methyl ester (l ‐NAME), l ‐N⁶‐(1‐iminoethyl)‐lysine (l ‐NIL)] in vivo will inhibit the above cascade and liver injury in an animal model of alcoholic steatohepatitis (ASH). Methods: Male Sprague–Dawley rats were gavaged daily with alcohol (6 g/kg/d) or dextrose for 10 weeks ± l ‐NAME, l ‐NIL, or vehicle. Systemic and intestinal NO levels were measured by nitrites and nitrates in urine and tissue samples, oxidative damage to the intestinal mucosa by protein carbonyl and nitrotyrosine, intestinal permeability by urinary sugar tests, and liver injury by histological inflammation scores, liver fat, and myeloperoxidase activity. Results: Alcohol caused tissue oxidation, gut leakiness, endotoxemia, and ASH. l ‐NIL and l ‐NAME, but not the d ‐enantiomers, attenuated all steps in the alcohol‐induced cascade including NO overproduction, oxidative tissue damage, gut leakiness, endotoxemia, hepatic inflammation, and liver injury. Conclusions: The mechanism we reported for alcohol‐induced intestinal barrier disruption in vitro — NO overproduction, oxidative tissue damage, leaky gut, endotoxemia, and liver injury — appears to be relevant in vivo in an animal model of alcohol‐induced liver injury. That iNOS inhibitors attenuated all steps of this cascade suggests that prevention of this cascade in alcoholics will protect the liver against the injurious effects of chronic alcohol and that iNOS may be a useful target for prevention of ALD.     

Comparison of Hepatocellular Carcinoma Patients With Alcoholic Liver Disease and Nonalcoholic Steatohepatitis

Background: Alcoholic hepatitis and nonalcoholic steatohepatitis (NASH) show different clinical features with similar liver histology, but both disorders may progress to cirrhosis and hepatocellular carcinoma (HCC). HCC arising in alcoholic liver disease (ALD) or NASH, without hepatitis B or C virus infection, has been a rare observation, and there are no studies comparing the characteristics of ALD and NASH patients with HCC. Therefore, we compared the characteristics of ALD and NASH patients with HCC.
Methods: A total of 1202 patients received a diagnosis of HCC at Tokyo Women's Medical University from 1989 to 2003, and their clinical data were collected prospectively. A clinical diagnosis was made to diagnose ALD, and clinical and histological changes were required to diagnose NASH. Of these patients, 88 received a diagnosis of HCC arising from ALD. Among them, a biopsy specimen was obtained in 50 patients (ALD-HCC group). We compared the clinical and histological characteristics of 50 ALD and 8 NASH patients (NASH-HCC group) associated with HCC. They all were negative for hepatitis virus infection by serological methods.
Results: The most significant difference between these groups was sex. Women were significantly more common in the NASH-HCC group (6% vs. 63%; p < 0.0001). The median age was 65 years in the ALD-HCC group and 68 years in the NASH-HCC group. The risk factors for NASH all were high in the NASH-HCC group. However, liver function tests were similar in these groups. In the ALD-HCC group, 46 (92%) patients showed severe fibrosis; 2 had septal fibrosis and 44 had cirrhosis. All patients in the NASH-HCC group showed severe fibrosis, and seven had cirrhosis.
Conclusions: Severe fibrosis might be an important risk factor for HCC. Patients who have ALD or NASH with cirrhosis may develop HCC. This seems to occur in a sufficient number of cases to warrant regular screening for this complication.     

Effect of Alcohol Use on Allograft Rejection Rates after Liver Transplantation for Alcoholic Liver Disease

Alcoholic liver disease is a major cause of liver disease and has become an ever-increasing indication for liver transplantation (LTx). Follow-up studies have reported a higher rate of alcohol recidivism in patients transplanted for alcoholic hepatitis, compared with those transplanted for endstage alcohol-associated cirrhosis. It is assumed widely that recurrent alcohol use is associated with reduced compliance with immune suppression and, as a result, an increased risk of graft rejection and loss. To assess this question, 209 alcoholic patients transplanted for either alcoholic hepatitis with cirrhosis or cirrhosis alone between January 1, 1986 and December 31, 1991 were followed, with a mean follow-up of 4.4 ± 0.6 years. There were 175 episodes of acute cellular rejection (ACR) that occurred in 137 patients, for an overall rejection rate of 83.7% or at a rate of 1.25 episodes/patient with rejection. The rate of ACR was three times as great in those who remained alcohol-abstinent (2.24 episodes/patient), compared with those who admitted to continued alcohol use (0.75 episodes/patient) ( p < 0.01). A total of 33 episodes of chronic rejection occurred in 26 patients, for an overall rate of 12.4%. As was the case for ACR, the chronic rejection rate was greater among those who were continuously alcohol-abstinent, compared with those who intermittently used alcohol after successful LTx.
There were no differences in the mean FK 506 or cyclosporin A levels in the groups with and without a rejection episode at the time the rejection episode was documented by liver biopsy. Contrary to generally accepted opinion, these data suggest that continued use of alcohol by liver transplant recipients is associated with a reduction, not an increase, in the rate of rejection.     

Alcohol Consumption and Alcoholic Liver Disease: Evidence of a Threshold Level of Effects of Ethanol

The effects of long-term moderate or "social" alcohol consumption (10-80 g daily intake) on the incidence of features of alcoholic liver disease (ALD) were delineated in a consecutive autopsy series of 210 males. The subjects' daily intake, as well as duration of alcohol consumption, was determined by an interview with the spouse or a close acquaintance and compared with semiquantitative histological scores for stage of ALD.
No significant increase in the incidence of features of ALD could be related to all-year daily intake of ethanol below 40 g (40 g equals 1.1 liter of beer, 0.44 liter of wine, and 0.11 liter of spirits). However, daily intake between 40–80 g increased relative liver weight on average 3.1 g/kg of body weight (p < 0.02), the frequency of fatty liver from 11.7 to 47.2% [relative risk (RR) = 4.4], and the frequency of mainly slight alcoholic hepatitis up to 16.7% (RR = 7.5). The incidence of both bridging fibrosis and liver cirrhosis increased significantly (RR = 8.8) only when daily intake exceeded 80 g. Amounts of ethanol exceeding 80 g did not relate to further increases in incidence of bridging fibrosis or liver cirrhosis.
These findings suggest that, in males, daily ingestion of ethanol below 40 g for a period of 25 years does not increase the risk of alcohol-related liver disease. In contrast, similar duration of daily intake between 40 and 80 g (mean 61.6 g) increased the risk of all but fibrotic liver lesions of ALD significantly and may thus represent a potential threshold level that significantly increases the risk of alcohol-related liver damage. Moreover, our results may suggest that, on an individual level, the risk function for liver fibrosis may not be directly dose-related, but rather, when a permissive threshold level is attained, further consumption is of no or little importance to the progression of ALD.     

Histochemical Study of Hyaluronate in Alcoholic Liver Disease

Recently, it has been reported that serum hyaluronate (hyaluronic acid; HA) concentrations increase in various liver diseases, especially in alcoholic liver disease (ALD), and serum HA concentration has been used as a marker for hepatic fibrosis. However, it is unknown whether hepatic HA contents in ALD increase by alcohol or not. In this study, we histochemically stained HA in liver biopsy specimens obtained from ALD patients while actively drinking and after abstinence to clarify the effects of alcohol on hepatic HA contents. Liver biopsy specimens were obtained from 13 patients with ALD and 10 patients with non-ALD. In ALD patients, liver biopsy was performed twice within 3 days, and 4 to 8 weeks after abstinence when serum levels of AST and ALT normalized. HA in biopsy specimens was stained histochemically with biotinylated HA binding protein. Staining intensity of HA in liver tissue was also determined by computer-assisted imaging analyzer. HA staining was clearly observed in sinusoidal wall and fibrous regions around the portal tract and central vein in liver diseases. HA staining intensities in patients actively drinking with ALD increased markedly, compared with those in patients with non-ALD, and these intensities decreased with abstinence. These results clearly suggest that hepatic HA contents in ALD may be increased by alcohol in addition to hepatic fibrosis, and, therefore, increased HA deposition in the liver may be reversible by abstinence of alcohol.