Early Alcoholic Liver Injury: Formation of Protein Adducts with Acetaldehyde and Lipid Peroxidation Products, and Expression of CYP2E1 AND CYP3A

The formation of protein adducts with reactive aldehydes resulting from ethanol metabolism and lipid peroxidation has been suggested to play a role in the pathogenesis of alcoholic liver injury. To gain further insight on the contribution of such aldehydes in alcoholic liver disease, we have compared the appearance of acetaldehyde, malondialdehyde, and 4-hydroxynonenal adducts with the expression of cytochrome P-450IIE1, and cytochrome P-4503A enzymes in the liver of rats fed alcohol with a high-fat diet for 2 to 4 weeks according to the Tsukamoto-French procedure and in control rats (high-fat liquid diet or no treatment). Urine alcohol and serum aminotransferase levels were recorded, and the liver pathology was scored from 0 to 10 according to the presence of steatosis, inflammation, necrosis, and fibrosis. The ethanol treatment resulted in the accumulation of fat, mild necrosis and inflammation, and a mean liver pathology score of 3 (range: 1 to 5). Liver specimens from the ethanol-fed animals with early alcohol-induced liver injury were found to contain perivenular, hepatocellular acetaldehyde adducts. Malondialdehyde and 4-hydroxynonenal adducts were also present showing a more diffuse staining pattern with occasional sinusoidal reactions. In the control animals, a faint positive reaction for the hydroxynonenal adduct occurred in some of the animals fed the high fat diet, whereas no specific staining was observed in the livers from the animals receiving no treatment Expression of both CYP2E1 and CYP3A correlated with the amount of protein adducts in the liver of alcohol-treated rats. Distinct CVP2E1 -positive immunohistochemistry was seen in 3 of 7 of the ethanol-fed animals. In 5 of 7 of the ethanol-fed animals, the staining intensities for CYP3A markedly exceeded those obtained from the controls. The present findings indicate that acetaldehyde and lipid peroxidatjon-derived adducts are generated in the early phase of alcohol-induced liver disease. The formation of protein adducts appears to be accompanied by induction of both CVP2E1 and CVP3A.     

Genetic polymorphisms of ADH2, ADH3, CYP4502E1 Dra-I and Pst-I, and ALDH2 in Spanish men: lack of association with alcoholism and alcoholic liver disease

BACKGROUND/AIMS: The relationship between polymorphisms at the alcohol dehydrogenase 2 (ADH(2)), ADH(3), CYP(450)2E1 and aldehyde dehydrogenase 2 (ALDH(2)) loci and the individual predisposition to alcoholism and alcoholic liver disease in Caucasians is controversial. METHODS: We determined the genotypes of ADH(2), ADH(3), CYP(450)2E1 (Pst-I and Dra-I) and ALDH(2) in 519 male Spaniards: 264 alcoholic subjects (47 without liver disease, 118 with non-cirrhotic liver disease and 99 with cirrhosis) and 255 non-alcoholic subjects (64 healthy controls, 110 with non-cirrhotic non-alcoholic liver disease and 81 with cirrhosis unrelated to alcohol). Genotyping was performed using PCR-RFLP methods on white cell DNA. RESULTS: The distribution of the allelic variants (allele *1 and allele *2) in the whole subjects analyzed was: ADH(2) 93.1% and 6.9%; ADH(3) 55.7 and 44.3%; CYP(450)2E1 Dra-I 11.2 and 88.8%; CYP(450)2E1 Pst-I 96.2 and 3.8% and ALDH2 100 and 0%, respectively. No differences were observed in the allelic distributions of the alcoholic and non-alcoholic subjects for the loci examined. Allele distribution in alcoholics with no liver disease, with alcoholic steatosis or hepatitis, and with cirrhosis was also similar. CONCLUSIONS: ADH(2), ADH(3), and CYP(450)2E1 Pst-I and Dra-I genetic variations are not related to alcoholism or susceptibility to alcoholic liver disease in our male population. ALDH(2) locus is monomorphic.     

Relationship between in vivo chlorzoxazone hydroxylation, hepatic cytochrome P450 2E1 content and liver injury in obese non-alcoholic fatty liver disease patients.

The aim of the present study was to test the hypothesis that induction of cytochrome P450 2E1 (CYP2E1) in the liver of patients with non-alcoholic fatty liver disease (NAFLD) is correlated both with the in vivo activity of the cytochrome and with the development of liver injury. For this purpose, the liver content of CYP2E1 was determined by Western blot and the CYP2E1 activity by the in vivo hydroxylation of chlorzoxazone (CLZ). The study groups were obese women with an average body mass index (BMI) of 40.3kg/m(2), who underwent therapeutic gastroplasty or gastrectomy with a gastro-jejunal anastomosis. Further, the hepatic histology was determined to establish the pathological score grouping the subjects into three categories: control, steatosis and steatohepatitis. The liver CYP2E1 content and the CLZ hydroxylation of obese patients with steatosis and, particularly, with steatohepatitis were significantly higher than controls and correlated positively with both the severity of the liver damage. These data provide evidence that CYP2E1 would be involved in the mechanism of liver injury found in obese NAFLD patients. Also, the correlation between liver CYP2E1 content and in vivo CLZ hydroxylation would validate the latter as a reliable indicator of liver injury in NAFLD, thus providing a simple and not invasive method to study these patients.     

phosphatase and tensin homolog is a differential diagnostic marker between nonalcoholic and alcoholic fatty liver disease

AIM: To investigate the protein expression of phosphatase and tensin homolog(PTEN) in human liver biopsies of patients with alcoholic and non-alcoholic liver disease.METHODS: PTEN protein expression was assessed by immunohistochemistry in formalin-fixed, paraffinembedded liver sections of patients with non-alcoholic fatty liver disease(NAFLD)(n = 44) or alcoholic liver disease(ALD)(n = 25). Liver resections obtained from 3 healthy subjects candidate for partial liver donation served as controls. Histological evaluations were performed by two experienced pathologists, and diagnoses established based on international criteria. The intensity of the PTEN staining in nuclei was compared between steatotic and non-steatotic areas of each liver fragment analyzed. For each liver specimen, the antibody-stained sections were examined and scored blindly by three independent observers, who were unaware of the patients' clinical history.RESULTS: In healthy individuals, PTEN immunostaining was intense in both the cytoplasm and nuclei of all hepatocytes. However, PTEN was strongly downregulated in both the nucleus and the cytoplasm of hepatocytes from steatotic areas in patients with NAFLD, independently of the disease stage. In contrast, no changes in PTEN protein expression were observed in patients with ALD, regardless of the presence of steatosis or the stage of the disease. The degree of PTEN downregulation in hepatocytes of patients with NAFLD correlated with the percentage of steatosis(r = 0.3061, P = 0.0459) and the BMI(r = 0.4268, P = 0.0043). Hovewer, in patients with ALD, PTEN expression was not correlated with the percentage of steatosis with or without obesity as a confounding factor(P = 0.5574). Finally, PTEN expression level in steatotic areas of ALD patients was significantly different from that seen in steatotic areas of NAFLD patients(P 0.0001).CONCLUSION: PTEN protein expression is downregulated early in NAFLD, but not in ALD. PTEN immunohistochemical detection could help in the differential diagnosis of NAFLD and ALD.     

Expression of p53, Bax and Bcl-2 proteins in hepatocytes in non-alcoholic fatty liver disease

INTRODUCTION Liver steatosis results from triglyceride accumulation in hepatocytes in the course of many diseases[1]. The failure of energetic processes in hepatocytes leads to progressive lipid increase in cytoplasm[2]. The most common cause of liver ste…     

Histological characteristics and prognosis in patients with fatty liver

OBJECTIVE: The clinical-pathological spectrum of fatty liver ranges from simple steatosis to end-stage fibrotic liver disease. However, no histological characteristics have been identified that can predict progression from pure steatosis to fibrotic liver disease in non-alcoholic fatty liver disease. The objective of this study was to investigate whether histological characteristics in patients with fatty liver without inflammation could predict mortality or development of cirrhosis. MATERIAL AND METHODS: A total of 417 patients had a liver biopsy performed, which showed fatty liver without inflammation. The population consisted of 170 non-alcoholic and 247 alcoholic fatty liver patients. The study cohort was linked through their unique personal identification number to The National Registry of Patients and the nationwide Registry of Causes of Death. RESULTS: Median follow-up time was 19.9 years in the non-alcoholic group and 12.8 years in the alcoholic group. Overall mortality in the non-alcoholic group was not related to morphological findings in the index liver biopsy. Mortality was significantly (p < 0.05) higher in alcoholic patients with severe steatosis. One non-alcoholic patient (0.6%) developed cirrhosis versus 54 alcoholic patients (22%) during the follow-up period. CONCLUSIONS: In patients with non-alcoholic fatty liver without inflammation, patients at risk for premature death cannot be identified by histological characteristics in the index liver biopsy. Patients with alcoholic fatty liver have a high risk for development of cirrhosis and increased mortality with the severity of steatosis in the index liver biopsy.     

Clinicopathological significance of oxidative cellular damage in non-alcoholic fatty liver diseases.

Oxidative stress may play an important role in the progression of simple steatosis to non-alcoholic steatohepatitis (NASH). Oxidative stress is generated through multiple sources, including oxidation of free fatty acids, cytochrome P4502E1, iron overload, and necro-inflammatory cytokines including tumor necrosis factor-alpha. Oxidative stress may trigger damage to cellular membranes and nuclear DNA, which results in lipid peroxidation and oxidative DNA damage, respectively. Here, we present our data on intrahepatic localization and clinico-pathological significance of oxidative stress-induced cellular damage in the patients with non-alcoholic fatty liver diseases (NAFLD). Our subjects were 23 patients with non-alcoholic simple fatty liver, 17 with NASH, and 7 with normal liver (control). Hepatic expression of 4-hydroxy-2'-nonenal (HNE) and 8-hydroxydeoxyguanosine (8-OHdG), as reliable markers of lipid peroxidation and oxidative DNA damage, was in situ detected by using commercially available monoclonal antibodies. While no HNE adducts were observed in control livers, they were frequently detected in NAFLD. In NASH, the localization of the HNE adducts was in the cytoplasm of sinusoidal cells and hepatocytes with a predominance in zone 3. The grade of necro-inflammation as well as the stage of fibrosis significantly correlated with the HNE labeling index. With respect to 8-OHdG, although no 8-OHdG expression was observed in normal liver and only a few in non-alcoholic simple fatty liver, 11 of 17 patients with NASH (65%) exhibited nuclear expression of 8-OHdG in hepatocytes and sinusoidal cells in areas of active inflammation. The 8-OHdG index significantly correlated with the grade of necro-inflammation, but not with the stage of fibrosis. Our observations suggest that oxidative cellular damage occurs frequently in livers with NAFLD and may be associated with some clinico-pathological features of NAFLD including liver fibrosis and possibly, hepatocarcinogenesis.     

Induction of cytochrome P450 2E1 [corrected] promotes liver injury in ob/ob mice

Cytochrome P450 2E1 (CYP2E1) activates several hepatotoxins and contributes to alcoholic liver damage. Obesity is a growing health problem in the United States. The aim of the present study was to evaluate whether acetone- or pyrazole-mediated induction of CYP2E1 can potentiate liver injury in obesity. CYP2E1 protein and activity were elevated in acetone- or pyrazole-treated obese and lean mice. Acetone or pyrazole induced distinct histological changes in liver and significantly higher aminotransferase enzymes in obese mice compared to obese controls or acetone- or pyrazole-treated lean mice. Higher caspase-3 activity and numerous apoptotic hepatocytes were observed in the acetone- or pyrazole-treated obese mice. Increased protein carbonyls, malondialdehyde, 4-hydroxynonenal-protein adducts, elevated levels of inducible nitric oxide synthase, and higher 3-nitrotyrosine protein adducts were found in livers of acetone- or pyrazole-treated obese animals, suggesting elevated oxidative and nitrosative stress. Liver tumor necrosis factor alpha levels were higher in pyrazole-treated animals. The CYP2E1 inhibitor chlormethiazole and iNOS inhibitor N-(3-(aminomethyl)-benzyl) acetamidine abrogated the toxicity and the oxidative/nitrosative stress elicited by the induction of CYP2E1. CONCLUSION: These results show that obesity contributes to oxidative stress and liver injury and that induction of CYP2E1 enhances these effects.     

非酒精性脂肪肝肝细胞色素P450ⅡE1的表达与氧化抗氧化的关系

目的研究非酒精性脂肪肝肝细胞色素Ｐ４５０ⅡＥ１表达及与氧化抗氧化的关系。方法用免疫组织化学的方法研究高脂饲料诱导的大鼠脂肪肝肝细胞色素Ｐ４５０ⅡＥ１的表达,同时检测肝组织中雨二醛（ＭＤＡ）和超氧化物歧化酶（ＳＯＤ）、谷胱甘肽（ＧＳＨ）、维生素Ｅ（ＶｉｔＥ）含量的变化,并分析其相关性。结果高脂饲料诱导的大鼠脂肪肝肝细胞色素Ｐ４５０ⅡＥ１在腺泡３区的表达增强,并从３区弥散至２区,与正常组相比,脂肪肝肝组织中ＭＤＡ的含量显著升高（Ｐ＜０．０１）．而ＳＯＤ、ＧＳＨ、ＶｉｔＥ的含量显著下降（Ｐ值分别小于０．０１、０．０５、０．０１）。相关分析表明,肝ＣＹＰＨＥＩ的表达与ＭＤＡ呈非常显著的正相关（Ｐ＜０．０１）、而与ＳＯＤ、ＧＳＨ、ＶｉｔＥ呈显著的负相关ｕ值分别小于０．０５、０．０５、０．０１）。结论非酒精性脂肪肝肝细胞色素Ｐ４５０ⅡＥ１在腺泡３区的表达增强,并呈弥散性的分布,与酒精性脂肪肝的表达相似,并可能与脂质过氧化反应有关。     

CYP2E1 activity in patients with alcoholic liver disease

Background/Aims: In addition to the possible toxicological impact of cytochrome P4502E1 (CYP2E1) in alcohol-induced liver damage, its activity can be regarded as a variable for dug action in patients with alcoholic liver disease as CYP2E1 is involved in the metabolism of several drugs, for example, paracetamol and halogenated anesthetics. The purpose of our study was to acquire detailed knowledge of CYP2E1 activity in patients with progressingly severe manifestations of alcoholic liver disease.Methods: The concentration ratio of 6-hydroxy-chlorzoxazone/chlorzoxazone in plasma 2 h after ingestion of 500 mg chlorzoxazone (so-called metabolic ratio) has been shown to reflect CYP2E1 activity in vivo. We examined CYP2E1 activity in 56 Caucasian inpatients with minor (n=20), more pronounced (n=14) and severe alcoholic liver disease (n=22). Alcohol abusers were compared to healthy teetotallers (n=14).Results: Metabolic ratios were increased 3-fold in actively drinking (ethanol-induced) compared to abstaining (non-induced) patients with alcoholic liver disease (1.19±0.84 vs. 0.44±0.45, mean±SD, (p<0.0001). CYP2E1 activity was significantly lower in non-induced patients with severe alcoholic liver disease (0.19±0.10) than in healthy controls (0.50±0.28, p<0.01), abstaning alcohol abusers with minor (0.67±0.60, p<0.01) and more pronounced alcoholic liver disease (0.53±0.31, p<0.01). When non-induced patients with alcoholic liver disease were arranged in progressing order of liver damage (minor, more pronounced, severe alcoholic liver disease), there was a significant decline in CYP2E1 activity (p=0.0008).Conclusions: In non-induced patients, CYP2E1 activity decreases in line with severity of alcoholic liver disease. CYP2E1-mediated drug metabolism is significantly impaired in severe alcoholic liver disease.     

A prospective study of isolated human hepatocyte function following liver resection for colorectal liver metastases: the effects of prior exposure to chemotherapy

BACKGROUND/AIMS: Chemotherapy is increasingly used prior to resection of colorectal liver metastases, yet few studies have addressed its effect on the viability and function of hepatocytes. This study evaluated the effect of pre-operative chemotherapy on human hepatocytes. METHODS: Studies were carried out on isolated hepatocytes from 47 patients undergoing hepatectomy for colorectal metastases. The function of drug metabolising enzymes in hepatocytes was assessed in vitro, as well as hepatocyte integrity and culture longevity. These results were compared between patients undergoing no pre-operative chemotherapy (N = 8), 5 fluorouracil (5FU) post-bowel resection (N = 20), and neo-adjuvant 5FU alone (N = 7) or in a combination with oxaliplatin (N = 12). RESULTS: Average cell viability at isolation determined by trypan blue dye exclusion was 71% with no significant difference between the no chemotherapy or pre-resection chemotherapy groups. There was no significant difference in LDH leakage and cellular ATP content over a 96-h time course between the patient treatment groups. The function of cytochromes P450 (CYP1A2, CYP2A6, CYP2C9, CYP2D6, CYP2E1, CYP3A4) and phase II enzymes (UDP-glucuronosyltransferase and sulphotransferase) was not adversely affected by pre-operative chemotherapy. CONCLUSIONS: Pre-resection chemotherapy does not impair the function or culture integrity of hepatocytes isolated at the time of liver resection.     

Cellular cytotoxicity against autologous hepatocytes in alcoholic liver disease

ABSTRACT— We tested lymphocyte cytotoxicity against autologous hepatocytes in patients with alcoholic liver disease (ALD). The following cytotoxicity values were found (mean ± SEM): alcohol-induced steatosis with or without fibrosis 16.5±2% (n = 29), alcoholic cirrhosis 28±4% (n = 13), controls with normal liver histology or minimal changes 6±2% (n = 11). The differences were statistically significant (both forms of ALD versus controls p<0.005). T-cell as well as non-T-cell-enriched lymphocyte fractions showed increased cytotoxicity in ALD. We did not observe a correlation between cellular cytotoxicity and the degree of biochemical or histological alterations within the groups tested. Thus, our study demonstrating enhanced cellular cytotoxicity against autologous hepatocytes in ALD further supports the hypothesis that cellular immune reactions are involved in the pathogenesis of ALD, especially of alcoholic cirrhosis.     

Histological characteristics and prognosis in patients with fatty liver

Objective The clinical-pathological spectrum of fatty liver ranges from simple steatosis to end-stage fibrotic liver disease. However, no histological characteristics have been identified that can predict progression from pure steatosis to fibrotic liver disease in non-alcoholic fatty liver disease. The objective of this study was to investigate whether histological characteristics in patients with fatty liver without inflammation could predict mortality or development of cirrhosis. Material and methods A total of 417 patients had a liver biopsy performed, which showed fatty liver without inflammation. The population consisted of 170 non-alcoholic and 247 alcoholic fatty liver patients. The study cohort was linked through their unique personal identification number to The National Registry of Patients and the nationwide Registry of Causes of Death. Results Median follow-up time was 19.9 years in the non-alcoholic group and 12.8 years in the alcoholic group. Overall mortality in the non-alcoholic group was not related to morphological findings in the index liver biopsy. Mortality was significantly (p<0.05) higher in alcoholic patients with severe steatosis. One non-alcoholic patient (0.6%) developed cirrhosis versus 54 alcoholic patients (22%) during the follow-up period. Conclusions In patients with non-alcoholic fatty liver without inflammation, patients at risk for premature death cannot be identified by histological characteristics in the index liver biopsy. Patients with alcoholic fatty liver have a high risk for development of cirrhosis and increased mortality with the severity of steatosis in the index liver biopsy.     

Dynamics of cytochrome P4502E1 activity in man: induction by ethanol and disappearance during withdrawal phase.

BACKGROUND/AIMS: Chronic ethanol consumption results in the induction of hepatic cytochrome P4502E1 (CYP2E1) in man, which is believed to play an important role in the pathogenesis of alcoholic liver disease. However, the amount and duration of alcohol intake associated with CYP2E1 induction is not known but limited information is available on the disappearance of CYP2E1 following alcohol withdrawal. METHODS: To study these questions, five healthy male volunteers received ethanol daily (40 g/day) over 4 weeks. CYP2E1 induction was monitored by using the chlorzoxazone test before and every week following the start of alcohol ingestion. In addition, CYP2E1 was also determined in five alcoholics 1, 3, 8 and 15 days following ethanol withdrawal and in five patients with non-alcoholic liver disease. RESULTS: A significant CYP2E1 induction occurred 1 week following the ingestion of 40 g ethanol per day and increased further after 4 weeks. The disappearance of CYP2E1 was found to be significant 3 days following ethanol withdrawal and further decreased up to day 8. Thereafter, no significant change occurred and CYP2E1 activities were comparable with those in patients with non-alcoholic liver disease. CONCLUSIONS: These data show a significant and quick induction of CYP2E1 activity, already at moderate alcohol consumption, which may be of importance in the pathogenesis of alcoholic liver disease, of ethanol, drug and vitamin A interactions and in alcohol associated carcinogenesis.     

Increased hepatocyte CYP2E1 expression in a rat nutritional model of hepatic steatosis with inflammation

BACKGROUND & AIMS: Nonalcoholic steatohepatitis is morphologically identical to alcoholic hepatitis and has multiple etiologic associations and an unknown pathogenesis. The present study used a rat nutritional model of hepatic steatosis with inflammation to test the hypothesis that induction of the alcohol-inducible hepatic cytochrome P450 (CYP) 2E1 is associated with production of steatohepatitis. METHODS: Rats received a diet devoid of methionine-choline. CYP2E1 protein was detected in liver sections by immunohistochemistry and in hepatic microsomal fractions by immunoblotting; CYP2E1 activity was detected by N-demethylation of N,N-dimethylnltrosamine (NDMA). CYP2E1 messenger RNA was analyzed by Northern blotting and slot blot hybridization. RESULTS: After 4 weeks of methionine-choline devoid diet, macrovesicular steatosis and an inflammatory infiltrate were prominent in hepatic acinar zone 3. CYP2E1 immunostaining was increased and had a more extensive acinar distribution corresponding to that of the steatosis. Microsomal CYP2E1 protein, NDMA activity, and hepatic CYP2E1 messenger RNA levels were all correspondingly increased. CONCLUSIONS: CYP2E1 is induced, partly at a pretranslational level, in this experimental form of steatohepatitis. The finding of biochemical and histological similarities between this nutritional model of hepatic steatosis with inflammation and alcoholic hepatitis indicates possible clues to common pathogenetic mechanisms. The relevance of this finding to human nonalcoholic steatohepatitis remains uncertain and requires further investigation of human liver specimens. (Gastroenterology 1996 Dec;111(6):1645-53)     

Expression and activity of the cytochrome P450 2E1 in patients with nonalcoholic steatosis and steatohepatitis.

BACKGROUND/AIMS: Nonalcoholic steatohepatitis (NASH) and nonalcoholic fatty liver (NAFL) have a different prognosis and should be dealt with differently. The pathogenesis of NASH implicates the overexpression of cytochrome P450 2E1 (CYP2E1). We investigated whether the noninvasive determination of CYP2E1 activity could replace a liver biopsy in order to differentiate NASH from NAFL. METHOD: Forty patients referred for suspicion of NASH underwent liver biopsy. In these patients, CYP2E1 activity was determined noninvasively by the 6-hydroxychlorzoxazone/chlorzoxazone (CHZ) ratio (CHZ test). Expression of CYP2E1 on liver slides was assessed by immunohistochemistry, and immunostaining for smooth muscle actin was used to assess the activation of hepatic stellate cells (HSC). RESULTS: Thirty patients with NASH were compared with 10 subjects with NAFL. No statistically significant difference could be identified for the clinical and biochemical parameters between the two groups. In the histology, steatosis was more important in NASH than in NAFL (P<0.0001). There was no difference either in the activity (CHZ test) or in the expression of CYP2E1 (immunohistochemistry) between patients with NASH and patients with NAFL. The degree of HSC activation was also comparable between the two groups. A positive and significant correlation was found between the activity of CYP2E1 and body mass index (P<0.001) as well as with the degree of steatosis (P=0.008). CONCLUSION: For patients suspected to have NASH, noninvasive tests including the determination of the CYP2E1 activity are unable to distinguish them from patients with steatosis.     

CYP2E1 activity before and after weight loss in morbidly obese subjects with nonalcoholic fatty liver disease

Previous studies suggest that hepatic cytochrome P450 2E1 (CYP2E1) activity is increased in individuals with chronic alcoholism, nonalcoholic steatohepatitis (NASH), and morbid obesity, and may contribute to liver disease. We studied 16 morbidly obese subjects with varying degrees of hepatic steatosis and 16 normal-weight controls. Obese subjects were evaluated at baseline, 6 weeks, and 1 year after gastroplasty, a procedure that leads to weight loss. Hepatic CYP2E1 activity was assessed by determination of the clearance of chlorzoxazone (CLZ), an in vivo CYP2E1-selective probe. Liver biopsy tissue was obtained during surgery for histopathology. Both the total and unbound oral CLZ clearance (Cl(u)/F) was elevated approximately threefold in morbidly obese subjects compared with controls (P <.001). The Cl(u)/F was significantly higher among subjects with steatosis involving >50% of hepatocytes, compared with those with steatosis in < or =50% of hepatocytes (P =.02). At postoperative week 6 and year 1, the median body mass index (BMI) of subjects who underwent gastroplasty decreased by 11% and 33%, total oral CLZ clearance declined by 16% (P <.01) and 46% (P <.05), and Cl(u)/F decreased by 18% (P <.05) and 35% (P =.16), respectively. Moreover, those subjects with a year 1 BMI <30 kg/m(2) exhibited a median Cl(u)/F that was 63% lower (P =.02) than the respective clearance for all other subjects. In conclusion, hepatic CYP2E1 activity is up-regulated in morbidly obese subjects. A positive association between the degree of steatosis and CYP2E1 activity preoperatively and between the extent of obesity and CYP2E1 activity postoperatively, suggests that CYP2E1 induction is related to or caused by hepatic pathology that results from morbid obesity.     

Induction of Cytochrome P-4502E1 by Ethanol in Rat Kupffer Cells

Ethanol has been shown to affect several Kupffer cell functions, but the mechanisms underlying these changes are unknown. One possible mediator is cytochrome P-4502E1 (CYP2E1), an ethanol-inducible enzyme that has been associated with toxic effects in the liver, as well as in many extrahepatic organs. To assess whether CYP2E1 can be induced by ethanol in Kupffer cells, male rats pair-fed ethanol-containing or control Lieber-DeCarli diets for 3 weeks were studied. Immunoblotting experiments showed that ethanol-treatment caused a 7-fold increase in CYP2E1 content both in Kupffer cells and hepatocytes. When expressed per milligram of S9 protein, the content of CYP2E1 in Kupffer cells was, however, 10 times lower than in hepatocytes. Immunohistochemical studies revealed that CYP2E1 is located in the endoplasmic reticulum of Kupffer cells in vivo and that it is also present in isolated Kupffer cells. In both Kupffer cells and hepatocytes, ethanol feeding increased the hydroxylation of p -nitrophenol, a relatively specific substrate for CYP2E1, demonstrating that the induced CYP2E1 was catalytically active. This reaction was significantly inhibited by anti-CYP2E1 IgG in both types of cells. Although CYP2E1 may not be the predominant pathway for ethanol metabolism in hepatocytes, it is possibly the major one in Kupffer cells. Thus, the induction of CYP2E1 by ethanol in these cells could cause significant changes in intracellular acetaldehyde concentrations which, together with increased lipid peroxidation, may contribute to the development of alcoholic liver injury.     

肝细胞色素P450 2E1在实验性肝纤维化组织中的表达

目的 研究肝细胞色素Ｐ４５０ ２Ｅ１在实验性肝纤维化组织中的表达。方法 ８只Ｗｉｓｔａｒ大鼠,建立四氯化碳（ＣＣｌ４）肝纤维化模型,用免疫组织化学方法观察肝纤维化模型肝组织中肝细胞色素Ｐ４５０ ２Ｅ１。结果 正常肝组织内,ＣＹＰ ２Ｅ１表达仅见于中央静脉周围区,主要表达于肝腺泡Ⅲ区,２～３层细胞厚,肝细胞浆和细胞膜可见ＣＹＰ ２Ｅ１表达。在ＣＣｌ４模型肝组织中,ＣＹＰ ２Ｅ１表达的强度增加,分布的