Expression of testosterone-dependent enzyme, carbonic anhydrase III, and oxidative stress in experimental alcoholic liver disease

We studied the sequential immunohistochemical appearance of androgen-dependent carbonic anhydrase (CA III) during the development of ethanol-induced liver injury using liver samples from castrated and noncastrated male micropigs. In castrated micropigs, the baseline expression of CA III was either low or absent, while distinct positive immunoreactions were found in zone 3 hepatocytes at 5 and 12 months after the initiation of the ethanol diet. The CA III enzyme and protein adducts of lipid peroxidation-derived aldehydic products, malondialdehyde and 4-hydroxynonenal, appeared together in the perivenous region, suggesting that the enzyme functions in an oxidative environment. The positive staining became more abundant and widespread during the progression of alcoholic liver disease. After 12 months, CA III was significantly more abundant in both the ethanol-fed noncastrated and castrated micropigs than in the control animals (P < 0.001, P < 0.05, respectively). CA III content was strikingly high in the ethanol-fed noncastrated animals, consistent with a potential role of androgens in the regulation of ethanol-induced CA III expression. The strongly positive CA III immunoreactions in the ethanol-fed noncastrated micropigs were associated with scant evidence of aldehydic protein adducts and minimal histopathology. Thus, enhanced expression of CA III during ethanol consumption may also account in part for gender differences in the susceptibility for alcohol-induced liver injury.

Induction of cytochrome P450 enzymes and generation of protein-aldehyde adducts are associated with sex-dependent sensitivity to alcohol-induced liver disease in micropigs

To assess possible links between ethanol-induced oxidant stress, expression of hepatic cytochrome P450 (CYP) enzymes, and sex steroid status, we used immunohistochemical methods to compare the generation of protein adducts of acetaldehyde (AA), malondialdehyde (MDA), and 4-hydroxynonenal (4-HNE) with the amounts of CYP2E1, CYP2A, and CYP3A in the livers of castrated and noncastrated male micropigs fed ethanol for 12 months. In castrated micropigs, ethanol feeding resulted in accumulation of fat, hepatocellular necrosis, inflammation, and centrilobular fibrosis, whereas only minimal histopathology was observed in their noncastrated counterparts. CYP2A and CYP3A were more prominent in the castrated animals than in the noncastrated micropigs. Ethanol feeding increased the hepatic content of all CYP forms. The most significant increases occurred in CYP2E1 and CYP3A in the noncastrated animals and in CYP2E1 and CYP2A in the castrated animals. Ethanol-fed castrated animals also showed the greatest abundance of perivenular adducts of AA, MDA, and HNE. In the noncastrated ethanol-fed micropigs a low expression of each CYP form was associated with scant evidence of aldehyde-protein adducts. Significant correlations emerged between the levels of different CYP forms, protein adducts, and plasma levels of sex steroids. The present findings indicate that the generation of protein-aldehyde adducts is associated with the induction of several cytochrome enzymes in a sex steroid-dependent manner. It appears that the premature, juvenile, metabolic phenotype, as induced by castration, favors liver damage. The present findings should be implicated in studies on the gender differences on the adverse effects of ethanol in the liver.

Aldehyde-protein adducts in the liver as a result of ethanol-induced oxidative stress

A number of systems that generate oxygen free radicals and reactive aldehydic species are activated by excessive ethanol consumption. Recent studies from human alcoholics and from experimental animals have indicated that acetaldehyde and aldehydic products of lipid peroxidation, which are generated in such processes, can bind to proteins forming stable adducts. Adduct formation may lead to several adverse consequences, such as interference with protein function, stimulation of fibrogenesis, and induction of immune responses. The presence of protein adducts in the centrilobular region of the liver in alcohol abusers with an early phase of histological liver damage indicates that adduct formation is one of the key events in the pathogenesis of alcoholic liver disease. Dietary supplementation with fat and/or iron strikingly increases the amount of aldehyde-derived epitopes in the liver together with promotion of fibrogenesis.

Hepatic lipid peroxidation in hereditary hemochromatosis and alcoholic liver injury

Studies in experimental animals have indicated that enhanced lipid peroxidation may play a role in the hepatic injury produced by iron overload or by excessive alcohol consumption. The aim of this study was to compare the formation of lipid peroxidation-derived aldehydes in the liver of patients with hereditary hemochromatosis (HH) and alcohol abuse. Liver biopsy specimens from 10 nondrinking patients with HH were evaluated. These patients were classified as having HH based on hepatic iron index or human leukocyte antigen identity with a known proband. All patients were homozygous for the Cys282Tyr mutation. In addition, 8 patients with alcoholic liver disease were examined, 2 of whom also had hemochromatosis. For comparison, 17 patients with liver diseases unrelated to iron overload or alcohol abuse were studied. Liver biopsy specimens were immunostained for protein adducts with malondialdehyde and 4-hydroxynonenal. Both malondialdehyde- and 4-hydroxynonenal-protein adducts were found from liver specimens of patients with HH and alcohol abuse in more abundant amounts than from patients in a control group. In alcoholics the adducts were primarily in zone 3, whereas in hemochromatosis staining had an acinar zone 1 predominance, which followed the localization of iron. The most abundant amounts of protein adducts were noted in patients with alcohol abuse plus iron overload. The data support the concept that both chronic alcohol use and iron overload induce hepatic lipid peroxidation. Through formation of reactive aldehydic products, excessive alcohol consumption and iron overload may have additive hepatotoxic effects.

Dopamine transporters increase in human brain after alcohol withdrawal

Dopaminergic transmission has been suggested to be a main mechanism mediating reinforcement, withdrawal and craving associated with alcohol addiction. We measured here striatal dopamine (DA) transporter binding from 27 alcoholics within 4 days after cessation of prolonged heavy drinking and after a 4-week period of abstinence with single photon emission computed tomography (SPECT) using a cocaine analogue, iodine-123-beta-CIT. Controls were 29 healthy volunteers. Blind quantitative analyses of the SPECT data revealed markedly lower DA transporter binding in alcoholics on admission for detoxification than in the non-alcoholic controls. After a 4-week period of abstinence DA transporter binding increased significantly in the alcoholics (P<0.0001) reaching the levels of the healthy controls. The most substantial recovery in DA transporter binding occurred during the first 4 days of abstinence. The data indicate that prolonged heavy drinking decreases DA transporter binding and disturbs synaptic dopamine transport. This may sensitize alcoholics to dopaminergic transmission, which may lead to early relapse after ethanol withdrawal.

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 CYP2E1-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 peroxidation-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 CYP2E1 and CYP3A.

Comparison of the Axis %CDT TIA and the CDTect method as laboratory tests of alcohol abuse

Carbohydrate-deficient transferrin (CDT) has been suggested as a specific marker of alcohol abuse. We designed this study to compare the conventional CDTect method (Pharmacia & Upjohn) and the new semiautomated Axis %CDT turbidimetric immunoassay (%CDT TIA) for their diagnostic performance to identify problem drinking. The sensitivities of the %CDT TIA and CDTect for correctly classifying heavy drinkers (n = 90) were 29% and 59% with the thresholds currently recommended by the manufacturers, respectively. In the control group (n = 114), which included hospitalized patients with abnormal serum transferrin concentrations, the CDTect assay gave 21 false-positive values (18%), whereas the %CDT TIA showed 100% specificity. With the cutoff limits based on the present healthy control group (mean + 2 SD), the sensitivities of the %CDT TIA and CDTect were 61% and 86%, respectively. For men, the ROC plot area of the CDTect results in comparisons of alcohol abusers and healthy controls was significantly (P < 0.05) higher than that of the %CDT TIA results, whereas for women, there was no significant difference in this respect. The slope and intercept (with 95% confidence intervals) for linear regression between CDTect and %CDT TIA were 0.13 (0.12-0.15) and 1.16 (0.73-1.59), respectively (S(y/x) = 1.51, r = 0.744). CDTect results correlated positively with serum transferrin (r = 0.224, P < 0.001), whereas the %CDT TIA results showed a slight inverse correlation with serum transferrin (r = -0.132, P = 0.07). The data suggest that CDTect is more sensitive than %CDT TIA in detecting drinking problems. However, the %CDT TIA method yields more specificity when analyzing samples from patients with high serum transferrin concentrations.

Serum IgA, IgG, and IgM antibodies directed against acetaldehyde-derived epitopes: relationship to liver disease severity and alcohol consumption

Chronic ethanol ingestion has been suggested to trigger the formation of antibodies that recognize acetaldehyde-protein condensates. In this study, assays for immunoglobulin (Ig) A, IgG, and IgM antibodies to acetaldehyde-derived adducts were performed on sera of 140 alcohol consumers, 19 patients with nonalcoholic liver disease (NALD), 35 healthy nondrinking controls, and 10 nondrinking patients with IgA or IgG myeloma. Anti-acetaldehyde (Ach)-adduct antibodies of each Ig isotype were found from the alcohol abusers. In alcoholic liver disease (ALD, n = 86) IgA titers were elevated in 69% of the patients. These titers were significantly higher than those from patients with NALD (P < .001), nondrinking controls (P < .001), or heavy drinkers (n = 54) without any clinical and biochemical signs of liver disease (P < .001). In contrast, anti-adduct IgG titers were significantly elevated both in ALD and in heavy drinkers as compared with patients with NALD (P < .001) or nondrinking controls (P < .01 and P < .05, respectively). The anti-adduct immunoglobulin (Ig)A, IgG, and IgM titers in patients with alcoholic liver disease (ALD) correlated with the combined clinical and laboratory index of liver disease severity (r(s) = .497, P < .001; r(s) = .361, P < .01; and r(s) = .322, P < .01). Anti-adduct IgA titers also correlated with serum bilirubin (r = .768, P < .001) and interleukin 6 (r = .504, P < .001). Anti-adduct IgG titers were, in turn, found to correlate with the presence of inflammation (P < .01) and necrosis (P < .01). During follow-up studies of individual patients, parallel changes were observed in the anti-adduct IgG titers, disease severity, and serum markers of fibrogenesis. The present results provide evidence that antibodies representing distinct Ig classes directed against acetaldehyde (Ach)-derived adducts of proteins are formed in alcoholic patients showing an association with the severity of liver disease. The follow-up data also support an association between such immune responses and the aggravation of liver disease.

Role of iron in NF-kappa B activation and cytokine gene expression by rat hepatic macrophages

A redox-sensitive nuclear factor, NF-kappa B, induces transcription of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in macrophages. The present study has investigated the role of iron in NF-kappa B activation and TNF-alpha and IL-6 expression by rat hepatic macrophages (HM). As an in vivo model, cholestatic liver injury was induced in rats by ligation of the common bile duct (BDL). During the first 2 wk after BDL, there was an increase in the hepatic level of thiobarbituric acid-reactive substances (TBARS) that was accompanied by the appearance of protein-malondialdehyde adducts in the periportal region. This increase was reduced after 3 wk. TNF-alpha and IL-6 mRNA levels in HM from the BDL rats were increased at 1 and 2 wk and attenuated at 3 wk. Gel mobility shift assay of HM nuclear extracts demonstrated the similar temporal pattern of enhanced NF-kappa B binding activity. Treatment of the BDL animals with 1,2-dimethyl-3-hydroxypyrid-4-one (L-1), a lipophilic iron chelator, suppressed the increases in hepatic TBARS by 64%, plasma alanine aminotransferase by 45%, and HM TNF-alpha and IL-6 mRNA by > 84%. Concomitantly, the HM NF-kappa B binding activity was reduced close to the level observed in sham-operated rats. Treatment of cultured HM with L-1 also blocked lipopolysaccharide-stimulated NF-kappa B activation and TNF-alpha and IL-6 expression at mRNA and protein levels. These results demonstrate that the iron chelator effectively blocks NF-kappa B activation and coordinate TNF-alpha and IL-6 gene upregulation by HM in cholestatic liver injury or under in vitro lipopolysaccharide stimulation. These findings support a pivotal role for iron in activation of NF-kappa B and cytokine gene expression by HM in vitro and in vivo.

Carbonic anhydrase II in the cerebrospinal fluid: its value as a disease marker

Carbonic anhydrase (CA) II is the predominant CA isoenzyme in the brain of mammals. We have recently developed a dual-label time-resolved immunofluorometric assay to quantify minute amounts of CA I and II in the cerebrospinal fluid (CSF). The present study was aimed at elucidating the clinical value of such measurements in the case of neurological disorders. Lumbar CSF samples were obtained from 111 patients suffering from various neurological diseases and from 97 control patients with no specific signs of central nervous system diseases. The highest CA II concentrations were found in patients with brain infarction (median 66.5 micrograms L-1, n = 20), whereas the control patients had markedly lower values (median 7.8 micrograms L-1, n = 97). Relative to a reference range calculated from the control material (10.2 +/- 17.2 micrograms L-1), the sensitivity of CA II measurement in differentiating brain infarction was 100%. Patients with transient ischaemic attack (median 11.2 micrograms L-1, n = 9), multiple sclerosis (median 14.7 micrograms L-1, n = 18) or epilepsy (median 20.3 micrograms L-1, n = 17) usually had CA II concentrations within the normal range, but those with central nervous system infection (n = 14), dementia (n = 19) or trigeminal neuralgia (n = 6) tended to have higher CA II levels in their CSF, the median values being 39.1 micrograms L-1, 45.5 micrograms L-1 and 44.0 micrograms L-1 respectively. The findings indicate that the concentration of CA II in the CSF marks disease activity in patients with brain damage. This finding could provide a basis for further studies estimating the value of CA II measurement as a new laboratory marker of diseases affecting the brain.

Iron overload in the rat pancreas following portacaval shunting and dietary iron supplementation

Reproduction of pancreatic iron overload in an animal model has been difficult to achieve primarily because of the first-pass extraction of iron by the liver. We hypothesized that portacaval shunting would avoid this hepatic phenomenon and increase pancreatic iron deposition. An end-to-side portacaval shunt was surgically created in male Sprague-Dawley rats, and they were subsequently fed a carbonyl iron-supplemented diet for 17 weeks. This resulted in marked iron accumulation in the pancreas (1621 +/- 188 micrograms/g) compared to minimal deposition in sham-operated rats fed the same diet (138 +/- 53 micrograms/g). Iron deposition in the acinar and centroacinar cells was confirmed histologically by Gomori staining, as well as by ultrastructural examination. Iron overloading was associated with enhanced oxidative stress evidenced by a twofold increase in the levels of glutathione disulfide and thiobarbituric acid-reactive substances. Also, adducts of proteins with malondialdehyde and 4-hydroxynonenal were demonstrated in acinar and ductal cells. Other apparent consequences of iron overload were a 50% reduction in pancreatic amylase content and a decrease in pancreatic protein concentration. These hypotrophic changes were associated with a reduced mass of zymogen granules in the acinar cells noted histologically. Our results show that a combination of portacaval shunting and carbonyl iron feeding achieve pancreatic iron overload and support the role of oxidative stress in the pathogenesis of iron-induced damage in the pancreas.

Sensitivity and specificity of carbohydrate-deficient transferrin as a marker of alcohol abuse are significantly influenced by alterations in serum transferrin: comparison of two methods

Despite a number of investigations suggesting the value of carbohydrate-deficient transferrin (CDT) as a marker of alcohol abuse, a variety of issues on the applicability of CDT measurements in clinical settings have remained unexplored. Earlier studies in this field have focused on the relationship of CDT and the amount of alcohol consumption or presence of liver disease, whereas the influence of alterations in serum transferrin concentrations on CDT has received less attention. In this study, we compared two different methods for measuring CDT (CDTect and %CDT) and total transferrin concentrations in a sample of 83 alcohol abusers (20 patients with alcoholic liver disease and 63 heavy drinkers who were devoid of liver disease, despite excessive alcohol consumption) and 89 controls, who were social drinkers or abstainers. The control population included 53 hospitalized patients with expected abnormalities in serum transferrin concentrations caused by conditions such as negative iron balance, pregnancy, or nonalcoholic liver disease. Both methods gave significantly higher values in alcohol abusers than in controls (p < 0.01), but the overall sensitivity for detecting alcohol abuse was clearly higher for CDTect (59%) than for %CDT (34%). The correlation between the results obtained by the two methods (r = 0.629) significantly improved, when the CDTect values were replaced by the ratio of CDTect/total transferrin (r = 0.770) (p < 0.05). There was a positive correlation between the CDTect and serum transferrin (r = 0.201, p < 0.01), which was significant both in the alcoholics (r = 0.240, p < 0.05), and especially in the controls (r = 0.727, p < 0.001). A significant inverse correlation emerged between %CDT and total transferrin (r = -0.302, p < 0.01). The sensitivities of CDTect and %CDT for correctly classifying alcohol abusers in the subgroup of alcoholic liver disease patients were 90% and 70% and in the subgroup of heavy drinkers without liver disease (49% and 22%), respectively. Specificities for CDTect and %CDT in this sample were 81% and 100%, respectively. However, in the subgroup of hospitalized control patients with abnormal serum transferrin, the specificity of CDTect was only 48%. According to present data, CDTect seems to be more sensitive than %CDT for detecting alcohol abuse. However, any alteration in serum total transferrin concentration markedly decreases the assay specificity. This should be considered when interpreting the assay results in patients with elevated serum transferrin, such as iron deficiency, pregnancy, or liver diseases.

Vitamin E decreases hepatic levels of aldehyde-derived peroxidation products in rats with iron overload

Hepatic iron overload can cause lipid peroxidation with the formation of aldehydic products, hepatocellular injury, and fibrosis. Vitamin E (alpha-tocopherol) may prevent peroxidation-induced hepatic damage. We used confocal laser scanning microscopy, digital image analysis, and immunohistochemical methods to quantitate aldehyde-derived peroxidation products in the liver of rats with experimental iron overload with or without supplemental vitamin E. A strong autofluorescent reaction colocalizing with iron deposits was present in the livers of iron-loaded rats. Fluorescent granules were unevenly distributed in the cytosol of both hepatocytes and Kupffer cells in the periportal regions. Immunohistochemical studies revealed the presence of malon-dialdehyde adducts in the periportal regions of the ironloaded rats. Vitamin E supplementation markedly reduced the fluorescence intensity and the amount of aldehyde-derived peroxidation products and changed the distribution of stainable iron and iron-associated peroxidation products such that their levels were much decreased in Kupffer cells. These results indicate that aldehyde-derived covalent chemical addition products are formed in the liver in iron overload. Vitamin E supplementation markedly reduces the amount of these compounds and changes their cellular distribution. These findings should be implicated in the role of antioxidant therapy in conditions causing iron overload and lipid peroxidation.

Carbohydrate-deficient transferrin as a marker of alcohol abuse: relationship to alcohol consumption, severity of liver disease, and fibrogenesis

Carbohydrate-deficient transferrin (CDT) measurements have been widely examined as a marker of excessive alcohol consumption, yet the information on the sensitivity of this method has remained controversial. In addition, little is known of the relationship of this marker and the severity of alcoholic liver disease (ALD). To clarify these issues, we analyzed serum samples from 373 alcohol abusers, including 200 problem drinkers with no apparent liver pathology, 173 patients with clinical or morphological evidence of ALD, and 42 healthy controls. CDT was analyzed by anion-exchange chromatography followed by radioimmunoassay. At a specificity of 100%, the sensitivity of CDT was 36% in problem drinkers reporting a mean of 710 +/- 80 (mean +/- 2SE) g of ethanol/week, as compared with the sensitivities of 44% and 35% for gamma-glutamyltranspeptidase (GGT) and mean corpuscular volume (MCV), respectively. In a subgroup of problem drinkers (n = 51) with the highest ethanol intakes (1160 +/- 180 g of ethanol/week) and severe dependence, the sensitivity of CDT increased to 64%, compared with 55% for GGT and 39% for MCV. In ALD, the CDT values were significantly higher than in the alcoholics with nonliver pathology. However, when such patients were classified according to the clinical, laboratory, and morphological severity of liver disease, CDT was found to be primarily elevated in those with the early stage of ALD, such that there was a significant negative correlation between CDT and the combined morphological index of disease severity (rs = -0.315, p < 0.05). ALD markers of fibrogenesis were elevated more frequently than CDT, showing significant positive correlations with the indices of disease severity.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequential acetaldehyde production, lipid peroxidation, and fibrogenesis in micropig model of alcohol-induced liver disease

The pathogenesis of alcohol-induced liver disease involves the adverse effects of ethanol metabolites and oxidative tissue injury. Previous studies indicated that covalent protein adducts with reactive aldehydes may be formed in alcohol consumers. To study the role of such protein adducts in the development of liver injury, we examined the sequential appearances of adducts of the ethanol metabolite acetaldehyde (AA) and of two products of lipid peroxidation, malondialdehyde (MDA) and 4-hydroxynonenol (HNE), in ethanol-fed micropigs. Immunohistochemical stainings using specific antibodies that recognize epitopes of each adduct were performed from liver biopsy specimens obtained at 1, 5, and 12 months from micropigs fed either control diet (n = 5) or ethanol-containing diets (n = 5). After 1 month on the ethanol diet, AA and MDA adducts were observed primarily in the perivenous regions co-localizing with each other and coinciding with increased concentrations of serum aminotransferase markers of liver injury. HNE adducts were usually less intense and more diffuse, and were also seen in some biopsy specimens from control animals. Although the most intense staining reactions at 5 months remained in zone 3, a more widespread distribution was usually seen together with increased evidence of steatonecrosis and focal inflammation. In terminal biopsies at 12 months, perivenous fibrosis was present in three of five biopsy specimens. More extensive pericentral and intralobular fibrosis was noted in one micropig fed ethanol for 21 months. These studies demonstrate that covalent adducts of proteins with reactive aldehydes are formed in early phases of alcohol-induced liver disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequential acetaldehyde production, lipid peroxidation, and fibrogenesis in micropig model of alcohol-induced liver disease

The pathogenesis of alcohol-induced liver disease involves the adverse effects of ethanol metabolites and oxidative tissue injury. Previous studies indicated that covalent protein adducts with reactive aldehydes may be formed in alcohol consumers. To study the role of such protein adducts in the development of liver injury, we examined the sequential appearances of adducts of the ethanol metabolite acetaldehyde (AA) and of two products of lipid peroxidation, malondialdehyde (MDA) and 4-hydroxynonenol (HNE), in ethanol-fed micropigs. Immunohistochemical stainings using specific antibodies that recognize epitopes of each adduct were performed from liver biopsy specimens obtained at 1, 5, and 12 months from micropigs fed either control diet (n = 5) or ethanol-containing diets (n = 5). After 1 month on the ethanol diet, AA and MDA adducts were observed primarily in the perivenous regions co-localizing with each other and coinciding with increased concentrations of serum aminotransferase markers of liver injury. HNE adducts were usually less intense and more diffuse, and were also seen in some biopsy specimens from control animals. Although the most intense staining reactions at 5 months remained in zone 3, a more widespread distribution was usually seen together with increased evidence of steatonecrosis and focal inflammation. In terminal biopsies at 12 months, perivenous fibrosis was present in three of five biopsy specimens. More extensive pericentral and intralobular fibrosis was noted in one micropig fed ethanol for 21 months. These studies demonstrate that covalent adducts of proteins with reactive aldehydes are formed in early phases of alcohol-induced liver disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Roles of oxidative stress in activation of Kupffer and Ito cells in liver fibrogenesis

An increasing body of experimental evidence is emerging to incriminate oxidative stress as a pivotal signal for liver fibrogenesis. This paper reviews the results from our studies testing this hypothesis. In the rat model of alcoholic liver disease, the importance of oxidative stress was supported by marked accentuation of liver fibrosis by dietary supplementation of iron, a pro-oxidant, and the significant correlation of the liver malondialdehyde (MDA) and 4-hydroxynonenal (4HNE) levels with the hepatic collagen accumulation. Both MDA and 4HNE adduct epitopes were detected intensely and diffusely in close association with collagen deposition. The direct cause and effect relationship between MDA/4HNE and Ito cell stimulation was indicated by the demonstration of Ito cell collagen gene induction by these aldehydes in culture. In primary cultures of rat Kupffer cells (KC), addition of antioxidants such as alpha-tocopherol acetate and succinate suppressed mRNA expression and the release of interleukin (IL)-6 and tumour necrosis factor alpha (TNF alpha). In rats with biliary fibrosis, an increase in the liver MDA level was accompanied by enhanced mRNA expression of procollagen alpha 1(I) and transforming growth factor beta 1 in Ito cells; and that of TNF alpha and IL-6 in KC. Furthermore, the gel shift assay of KC nuclear extracts showed enhanced NF-kB DNA binding activity. These results support the proposal that enhanced oxidative stress constitutes an important signal for activation of Kupffer and Ito cells in experimental liver fibrogenesis.

Experimental liver cirrhosis induced by alcohol and iron

To determine if alcoholic liver fibrogenesis is exacerbated by dietary iron supplementation, carbonyl iron (0.25% wt/vol) was intragastrically infused with or without ethanol to rats for 16 wk. Carbonyl iron had no effect on blood alcohol concentration, hepatic biochemical measurements, or liver histology in control animals. In both ethanol-fed and control rats, the supplementation produced a two- to threefold increase in the mean hepatic non-heme iron concentration but it remained within or near the range found in normal human subjects. As previously shown, the concentrations of liver malondialdehyde (MDA), liver 4-hydroxynonenal (4HNE), and serum aminotransferases (ALT, AST) were significantly elevated by ethanol infusion alone. The addition of iron supplementation to ethanol resulted in a further twofold increment in mean MDA, 4HNE, ALT, and AST. On histological examination, focal fibrosis was found < 30% of the rats fed ethanol alone. In animals given both ethanol and iron, fibrosis was present in all, with a diffuse central-central bridging pattern in 60%, and two animals (17%) developed micronodular cirrhosis. The iron-potentiated alcoholic liver fibrogenesis was closely associated with intense and diffuse immunostaining for MDA and 4HNE adduct epitopes in the livers. Furthermore, in these animals, accentuated increases in procollagen alpha 1(I) and TGF beta 1 mRNA levels were found in both liver tissues and freshly isolated hepatic stellate cells, perisinusoidal cells believed to be a major source of extracellular matrices in liver fibrosis. The dietary iron supplementation to intragastric ethanol infusion exacerbates hepatocyte damage, promotes liver fibrogenesis, and produces evident cirrhosis in some animals. These results provide evidence for a critical role of iron and iron-catalyzed oxidant stress in progression of alcoholic liver disease.

High-activity carbonic anhydrase isoenzyme (CA II) in human gallbladder epithelium

Acidification of bile is one of the factors that prevents calcium precipitation and thereby gallstone formation. Carbonic anhydrase II (CA II) has previously been shown to be one of the key factors in the human alimentary tract that regulates the acid-base balance. We demonstrated CA II expression in the human gallbladder epithelium using immunohistochemical techniques, elucidated the CA II content of the epithelium by digital image analysis of the immunohistochemically stained enzyme in samples from 16 patients undergoing cholecystectomy, and correlated the results with the calcium content of the gallstones. Nine patients had symptomatic gallstone disease and seven an acalculous, histologically normal gallbladder. The patients were classified into two groups on the basis of the calcium content of their gallstones: no gallstones or gallstones containing no calcium (Group 1) and gallstones with 2-87% calcium by weight (Group 2). The immunohistochemical techniques showed distinct epithelial CA II-positive staining in most of the gallbladder samples, but digital image analysis revealed distinct variations in staining intensity among them. The median staining intensity index was significantly higher in Group 1 (0.4463) than in Group 2 (0.2376; p = 0.0262). The results suggest that CA II is abundantly expressed in the normal gallbladder epithelium and that decreased expression may be associated with the formation of calcified gallstones. These findings are relevant to the pathogenesis of gallstone disease.

Characteristics of symptomatic gallbladder disease in patients with either solitary or multiple cholesterol gallstones

Recent studies have indicated that solitary or multiple gallstones may differ with respect to the conditions favoring their formation, such as nucleation time. We examined the clinical, histological and laboratory characteristics of symptomatic gallstone disease in a series of 125 consecutive patients with either solitary (n = 33) or multiple (n = 92) cholesterol gallstones undergoing cholecystectomy. The nature of biliary pain was found to differ in the two groups. Histological diagnoses of acute cholecystitis and gallbladder cancer was more frequent in the patients with multiple stones, and cholesterolosis in those with solitary stones. Furthermore, the stone cholesterol content was higher in the solitary stone group than in the multiple stone group. Morbid complications such as cholangitis and pancreatitis were rare and occurred only in the multiple stone group. The results support the view that gallbladder disease presents histological evidence of biliary complications more often in patients with multiple cholesterol stones than in those with solitary stones.

Covalent protein adducts in the liver as a result of ethanol metabolism and lipid peroxidation

BACKGROUND

The primary mechanisms of ethanol-induced tissue damage have been suggested to include aldehyde-derived protein modifications resulting from ethanol metabolism and lipid peroxidation. Conjugation of reactive aldehydes to a variety of target proteins and cellular constituents have been recently reported. This research was undertaken in order to examine the presence of covalent chemical addition products (adducts) of proteins and acetaldehyde, the first metabolite of ethanol, and those with malondialdehyde, a product of lipid peroxidation, as formed in vivo.

EXPERIMENTAL DESIGN

Specific antibodies recognizing acetaldehyde- and malondialdehyde-modified epitopes in proteins were used in immunoperoxidase and double immunofluorescence stainings of liver specimens obtained from ethanol-fed rats and micropigs and from human alcoholics.

RESULTS

The centrilobular region of the liver contained the protein modifications both in alcohol-consuming humans and in animals fed ethanol before any apparent histologic damage. With inflammation and fibrosis, such protein modifications were more widespread, and the positive staining for the malondialdehyde-derived modification became more dominant. The presence of the adducts colocalized with the areas of fatty infiltration, focal necrosis and fibrosis. In addition, the erythrocytes of alcohol consumers were found to contain such modifications.

CONCLUSIONS

The studies support the view that covalent damage to proteins and cellular constituents induced by aldehyde-derived modifications in vivo may play a role in the sequence of events leading to liver disease in alcohol consumers. Species and dietary differences may be important in the relative contribution of lipid peroxidation to alcohol-induced tissue damage.

Spontaneous intraabdominal haemorrhage caused by segmental mediolytic arteritis in a patient with systemic lupus erythematosus--an underestimated entity of autoimmune origin?

We describe the sixth known case of segmental mediolytic arteritis and the third in a survivor. A 70-year-old woman had intraabdominal bleeding due to a ruptured aneurysm of the omental artery. Interestingly, this patient also had a systemic lupus erythematosus. This report gives further support to the role of immune abnormalities underlying segmental mediolytic arteritis.

Segmental mediolytic arteritis--electronmicroscopic and immunohistochemical study

We examined specimens of human gastroepiploic artery aneurysm from a patient having several visceral aneurysms using electronmicroscopic and immunohistochemical techniques. The histopathological and ultrastructural findings confirmed the diagnosis of segmental mediolytic arteritis. Arterial smooth muscle cells from the gastroepiploic artery contained cytoplasmic vacuoles, media was thin and the internal elastic membrane showed distortion. X-ray microanalysis revealed calcium deposits in the medial extracellular space. Antigenic determinants of human immunoglobulins, fibrinogen, complement C3a and factor VIII were demonstrated in the injured artery wall, suggesting that immunocomplexes deposited in the artery wall may be associated with local injury. These findings support the role of autoimmune disorders in the pathogenesis of segmental mediolytic arteritis.

Centrilobular distribution of acetaldehyde and collagen in the ethanol-fed micropig

We established a new animal model of alcoholic liver disease in the micropig, a species that consumes ethanol voluntarily in the diet. Ten micropigs were pair-fed diets containing 40% of calories as ethanol or cornstarch with identical amounts of fat, protein and micronutrients for 12 mo. Liver histopathology in the ethanol-fed pigs included steatonecrosis in all five and interstitial and perivenous fibrosis in three. Electron microscopy showed Ito-cell transformation with perisinusoidal collagen accumulation. Acetaldehyde adducts were found by immunofluorescence in the centrilobular region and were focused in perivenous zone 3 of all ethanol-fed animals. Protein and triglyceride levels were increased, whereas vitamin A and iron levels were decreased in liver homogenates from ethanol-fed animals. Thus, in this new animal model of alcoholism, ethanol feeding produced the features of alcoholic liver disease concurrent with hepatic deficiency of selected nutrients. Histological and immunofluorescent studies provide in vivo evidence that perivenous collagen deposition is linked to ethanol metabolism and acetaldehyde production.