Johanna Hietala

Immune Responses to Ethanol Metabolites and Cytokine Profiles Differentiate Alcoholics with or without Liver Disease

OBJECTIVES:Excessive alcohol consumption is associated with the generation of antibodies against neoantigens induced by ethanol metabolism. However, the associations between such immune responses, ethanol consumption, and liver injury remain unclear.METHODS:Eight-six male alcoholics with (n = 54) or without (n = 32) liver disease, and 20 male volunteers (6 abstainers, 14 moderate drinkers) underwent clinical, morphological, and biochemical assessments of liver status and ethanol consumption.RESULTS:Antiacetaldehyde adduct IgAs in both groups of alcoholics were significantly higher than those in the controls. Elevated IgGs occurred in patients with liver disease, whereas IgMs were high in the heavy drinkers without apparent liver disease. Liver disease patients had high levels of both proinflammatory (IL-2, IL-6, IL-8, TNF-α) and antiinflammatory (IL-10) cytokines, whereas those without liver disease showed elevated IL-6, IL-8, and IL-10 only. Ethanol consumption correlated significantly with antiadduct IgA and IL-6 levels, which also showed parallel changes upon abstinence.CONCLUSIONS:Alcoholic liver disease is associated with the generation of IgAs and IgGs against acetaldehyde-derived antigens and enhanced levels of both pro- and antiinflammatory cytokines, whereas elevated IgA, IL-6, and IL-10 characterize alcoholics without liver disease. These data suggest that immunological mechanisms may play a role in the sequence of events leading to liver disease in some patients with excessive drinking.

Immune responses against oxidative stress-derived antigens are associated with increased circulating tumor necrosis factor-α in heavy drinkers

Growing evidence indicates that pro-inflammatory cytokines play a key role in alcoholic liver disease (ALD). This study investigates whether immune response toward oxidative stress-derived antigens could be involved in promoting cytokine production in alcohol abusers. Cytokine profile and circulating IgG against human serum albumin modified by malondialdehyde (MDA-HSA) and against oxidized cardiolipin (Ox-CL) were evaluated in 59 heavy drinkers (HD) with (n=30) or without (n=29) ALD and 34 healthy controls. IgG against MDA-HSA and Ox-CL were significantly higher in HD with ALD than in HD without liver injury or healthy controls. The elevation of these antibodies was associated with higher circulating levels of IL-2 (p=0.005) and TNF-alpha (p=0.001), but not of IL-6 or IL-8. The prevalence of abnormal TNF-alpha was 5-fold higher in HD with oxidative stress-induced IgG than in those without. HD with the combined elevation of both TNF-alpha and oxidative stress-induced IgG had 11-fold (OR 10.7; 95%CI 1.2-97.2; p=0.023) greater risk of advanced ALD than those with high TNF-alpha, but no immune responses. Moreover, the combined elevation of TNF-alpha and lipid peroxidation-derived IgG was an independent predictor of ALD in HD. We propose that immune responses towards oxidative stress-derived antigen promote TNF-alpha production and contribute to liver damage in alcohol abusers.

Biomarkers of Liver Status in Heavy Drinkers, Moderate Drinkers and Abstainers

AIMS Although a wide variety of biomarkers reflecting liver status are known to be influenced by excessive ethanol consumption, the dose-response relationships between ethanol intake and marker changes have remained less understood. METHODS Serum gamma-glutamyltransferase (GGT), aspartate aminotransferase (AST), alanine aminotransferase (ALT) activities, and ferritin and albumin protein concentrations were compared in a large population of heavy drinkers (105 men, 28 women), moderate drinkers (781 men, 723 women) and abstainers (252 men, 433 women), who were devoid of apparent liver disease. RESULTS In heavy drinkers, serum GGT, AST, ALT, ferritin and albumin were all significantly higher than in moderate drinkers or abstainers (P < 0.001 for all comparisons). The highest incidences of elevated values were found for GGT (62%) followed by AST (53%), ALT (39%), ferritin (34%) and albumin (20%). Serum GGT (P < 0.001), ALT (P < 0.01) and ferritin (P < 0.05) in moderate drinkers were also higher than the levels observed in abstainers. When the study population was further divided into subgroups according to gender, significant differences between moderate drinkers and abstainers in GGT and ALT were noted in men whereas not in women. CONCLUSIONS The data demonstrate that biomarkers of alcohol abuse and liver function may respond to even rather low levels of ethanol intake in a gender-dependent manner, which should be implicated in studies on the early-phase interactions of ethanol and the liver and in the definition of normal ranges for such biomarkers.

Gender-dependent impacts of body mass index and moderate alcohol consumption on serum uric acid-an index of oxidant stress status?

Uric acid seems to be causally involved in a variety of medical disorders involving oxidative stress. Although alcohol abuse and obesity are known to increase serum uric acid, the interactions between moderate drinking, adiposity, and uric acid metabolism have remained poorly understood. We examined serum uric acid concentrations from 2062 apparently healthy volunteers (970 men, 1092 women) reporting either no alcohol (abstainers) or <40 g of ethanol consumption per day (moderate drinkers). The study population was further classified according to BMI as follows: <19 (underweight), 19-25 (normal weight), 25-30 (overweight), and >30 (obese). Serum uric acid concentrations in male moderate drinkers were significantly higher, and in females they were lower, than in the corresponding groups of abstainers. In the BMI-based subgroups, the highest concentrations were found in those who were overweight or obese. Significant two-factor interactions occurred between gender and drinking status (p<0.001) and between gender and BMI (p<0.02). Serum uric acid also correlated with indices of hepatocellular health (GGT, ALT, AST). The data indicate distinct gender-dependent impacts of alcohol consumption and BMI on serum uric acid. These findings should be applicable to the assessment of oxidative stress status and associated morbidity in alcohol consumers and individuals with excess body weight.

An inverse relationship between markers of fibrogenesis and collagen degradation in patients with or without alcoholic liver disease.

OBJECTIVES:Excessive deposition of collagen leading to cirrhosis is a major complication of alcohol abuse. However, the mechanisms behind the accumulation of the extracellular matrix proteins are poorly understood.METHODS:We measured serum markers of collagen degradation (β-CTx), fibrogenesis (PINP, PIIINP), and pro- and anti-inflammatory cytokines from 84 male heavy drinkers, who were either with (N = 52) or without (N = 32) clinical or histological signs of alcoholic liver disease (ALD), and from 20 healthy nonalcoholic controls.RESULTS:Serum β-CTx levels in ALD patients were significantly lower than in healthy controls or in the alcoholics without liver disease, while PINP and PIIINP, reflecting type I and type III collagen synthesis, respectively, were significantly increased. The alcoholics without liver disease showed values, that were not significantly different from those of healthy controls. Serum β-CTx correlated negatively with serum PIIINP and proinflammatory cytokines (IL-2, IL-6, IL-8, TNF-α), and positively with anti-inflammatory cytokines (IL-1, TGF-β), whereas serum PIIINP correlated positively with these proinflammatory cytokines and negatively with the anti-inflammatory cytokines. Calculation of PIIINP/β-CTx ratio was found to yield an excellent sensitivity (94%) and specificity (98%) in differentiating the alcoholics with liver disease.CONCLUSION:The present findings indicate a positive relationship between markers of collagen biosynthesis and proinflammatory cytokines, and a negative relationship between these markers and a marker of collagen degradation and anti-inflammatory cytokines, suggesting that a disturbed balance in these cellular responses may facilitate fibrogenesis and play a pivotal role in the pathogenesis of ALD. These findings should also be implicated in the development of noninvasive tools for discriminating individuals at risk for fibrogenesis.

Co-Occurrence of IgA Antibodies Against Ethanol Metabolites and Tissue Transglutaminase in Alcohol Consumers: Correlation with Proinflammatory Cytokines and Markers of Fibrogenesis

IgA antibodies to tissue transglutaminase have been suggested to be specific indicators of celiac disease. However, no studies have addressed the relationships between such antibodies and alcohol abuse, which is also a common cause of IgA-isotype immune responses and tissue injury in the gastrointestinal tract and liver. Here, measurements of specific IgAs against tissue transglutaminase and proteins modified by acetaldehyde, the first metabolite of ethanol, showed significantly higher levels of both antibodies in alcoholic liver disease patients than in healthy controls or heavy drinkers without liver disease. These antibodies also significantly co-occurred in heavy drinkers without liver disease, moderate drinkers, and abstainers, and correlated with biomarkers of alcohol consumption, proinflammatory cytokines and markers of fibrogenesis. The data suggests a link between such immune responses, perturbations in cytokine profiles and fibrogenesis, which should be implicated in studies on the pathogenesis and diagnosis of ethanol-induced tissue injury and celiac disease.

Obesity and the clinical use of serum GGT activity as a marker of heavy drinking

Objective. Gamma‐glutamyl transferase (GGT) is a widely used clinical marker of alcohol abuse. However, although obesity may also elevate serum GGT activities, the effects of overweight on the interpretation of GGT testing have remained poorly defined. Material and methods. GGT activities from 1147 moderate drinkers and 449 abstainers who were classified according to body mass index (BMI) were compared with those of 208 heavy drinkers admitted for detoxification. Results. GGT upper normal limits, defined based on normal weight abstainers (men 53 U/L; women 45 U/L) were lower than those based on moderate drinkers (men 68 U/L; women 50 U/L). The relative increases in GGT activities in male moderate drinkers with overweight (54%) or obesity (125%) exceeded the corresponding changes found in women (25% and 75%, respectively). The BMI‐dependent variation on the sensitivity of GGT for correctly classifying heavy drinkers ranged from 29% to 67%. The rates of false‐positive values in the subgroups from low to high BMI varied from 0% to 27%, respectively. Conclusions. The data indicate that the diagnostic value of serum GGT testing could be improved by using reference data derived from databases of abstainers with normal weight or BMI‐based categorization of reference ranges.