Immune responses in alcoholic liver disease

A dynamic flux in natural killer cell subsets as a function of the duration of alcohol ingestion

BACKGROUND

Chronic ethanol (EtOH) consumption is associated with a wide variety of immune abnormalities including changes in T cells, B cells, dendritic cells, and natural killer (NK) cells. However, there is conflicting information as to the direction of such immune changes. The hypothesis that was tested in this report is that, for NK cells, the changes can vary as a function of the duration of alcohol ingestion.

METHODS

Using the Meadows-Cook murine model of chronic alcohol ingestion, the changes in NK cell function and subset distribution were examined as a function of the duration of alcohol ingestion.

RESULTS

Acute alcohol ingestion resulted in decreased number and cytotoxic function of NK cells with no effect on intracellular interferon gamma expression. These abnormalities normalized after 12 to 14 days of alcohol ingestion and there was an increase of NK cell number and cytotoxicity after 8 weeks of continued EtOH ingestion. Ten weeks of continued alcohol consumption results in a significant decrease in the Ly49H+ CD11b+ CD27- splenic NK cell subset; this difference continued to be significant at 30 weeks.

CONCLUSIONS

This report may explain some of the conflicting data in the literature that examined NK cell activity in alcoholic patients. It is apparent that various abnormalities can be seen in NK cell activity and subset distribution with the flux being a function of the duration of alcohol ingestion. The demonstration of a decrease in the Ly49H+ subset (which is known to be involved in resisting murine cytomegalovirus infection) may explain the reported increase in susceptibility to some viral infections in chronic alcohol abuse. Another novel finding is that changes of some subsets of NK cells are not evident until at least 10 weeks of continued EtOH consumption.

B-cell studies in chronic ethanol mice

Chronic alcohol abuse leads to multiple defects in the immune system, leading to an increased risk of infectious disease and malignancy. Immune lesions encompass both the innate and adaptive arms and include deficiencies in the B-cell compartment. Long-term alcoholics exhibit loss of B cells in the periphery and diminished ability to generate protective antibodies. To better mimic the chronic alcoholic patient, our group has used an ethanol-in-drinking-water mouse model. Mice consuming alcohol in this manner progressively develop a range of immune abnormalities, including defects in humoral immunity. To document and explore B-cell lesions in ethanol-consuming mice, our laboratory has used a broad panel of technologies. These include protocols to define the physical state of B cells in the bone marrow and periphery, in vitro approaches to test B-cell activation potential and in vivo experiments to document the humoral competence of the host. These key techniques are detailed in the present chapter.

Alcoholic liver disease: new insights into mechanisms and preventative strategies

Alcoholic liver disease has a known aetiology but a complex pathogenesis. It is an extremely common disease with a high mortality, but the reason why only a relatively small proportion of heavy drinkers progress to advanced disease remains elusive. Accumulating evidence points towards an elaborate interplay between metabolism, inflammation and immunity in the development of steatosis, hepatitis and fibrosis. These complex pathways leading to liver injury offer many potential susceptibility loci, as well as sites for potential therapeutic intervention.

Autoimmune responses against oxidant stress and acetaldehyde-derived epitopes in human alcohol consumers

BACKGROUND

Studies in experimental animals have indicated that chronic ethanol ingestion triggers the formation of antibodies directed against proteins modified with reactive metabolites of ethanol and products of lipid peroxidation. However, the nature and prevalence of such antibodies have not been compared previously in alcoholic patients.

METHODS

Autoantibodies against adducts with acetaldehyde- (AA), malondialdehyde- (MDA), and oxidized epitopes (Ox) were examined from sera of 54 alcohol consumers with (n = 28) or without (n = 26) liver disease, and from 20 nondrinking controls.

RESULTS

Anti-AA-adduct IgA and IgG antibodies were elevated in 64% and 31% of patients with biopsy-proven alcoholic liver disease (ALD, n = 28), respectively. The IgA titers were significantly higher than those from nondrinking controls (p < 0.001), or heavy drinkers without significant liver disease (p < 0.001). Anti-MDA adduct titers (IgG) were elevated in 70% of the ALD patients. These titers were significantly higher (p < 0.001) than those from nondrinking controls, or heavy drinkers without liver disease. Antibodies (IgG) against Ox epitopes occurred in 43% of ALD patients, and the titers also were significantly higher (p < 0.05) than those from nondrinking controls. The anti-AA and anti-MDA adduct titers in ALD patients correlated significantly with the combined clinical and laboratory index (CCLI) of liver disease severity (r(s) = 0.449, p < 0.05; r(s) = 0.566, p < 0.01, respectively), the highest prevalences of anti-AA-adducts (73%) and anti-MDA-adducts (76%) occurring in ALD patients with cirrhosis.

CONCLUSIONS

The present results indicated that autoantibodies against several distinct types of protein modifications are generated in ALD patients showing an association with the severity of liver disease.

Effect of biphenyl dimethyl dicarboxylate on the humoral immunosuppression by ethanol

The present study was undertaken to investigate the effect of biphenyl dimethyl dicarboxylate (PMC) on the humoral immunosuppression by ethanol (EtOH) in ICR mice. PMC at a dose of 6 mg/kg was orally administered to mice daily for 28 consecutive days, and the control mice were given vehicle. Mice treated with EtOH were given freely with 20% EtOH instead of water. The results of this study are summarized as follows; a gain of body weight and the relative weights of spleen and liver were significantly increased by combination of PMC and EtOH, as compared with those in mice treated with EtOH alone. Splenic plaque forming cells (PFC) and hemagglutination (HA) titers to sheep red blood cells (SRBC), and the secondary IgG antibody response to bovine serum albumin (BSA) were decreased by the treatment of EtOH alone, then restored to normal level by PMC treatment. The elevations of serum glutamic-pyruvic transaminase (S-GPT) and total protein levels caused by EtOH were reduced to normal level by the combination of PMC and EtOH. In addition, lower serum albumin and A/G ratio were also increased to normal level. These findings indicate that PMC has a protective effect against EtOH-induced humoral immunosuppression.

Detection of circulating antibodies against malondialdehyde-acetaldehyde adducts in patients with alcohol-induced liver disease

Acetaldehyde and malonildialdehyde can form hybrid protein adducts, named MAA adducts that have strong immunogenic properties. The formation of MAA adducts in the liver of chronic alcohol-fed rats is associated with the development of circulating antibodies that specifically recognized these adducts. The aim of this study was to examine whether MAA adducts might participate in the immune response associated with human alcohol-induced liver disease. Circulating antibodies against MAA adducts were evaluated in 50 patients with alcohol-induced hepatitis or cirrhosis, in 40 patients with non-alcohol-induced liver disease, in 15 heavy drinkers without liver damage and in 40 healthy controls by enzyme-linked immunosorbent assays (ELISA). Immunoglobulin G (IgG) reacting with MAA-modified proteins were significantly increased in the patients with alcohol-induced cirrhosis or hepatitis. The individual levels of anti-MAA IgG in those patients were associated with the severity of liver damage. Anti-MAA antibodies were also positively correlated with the levels of IgG recognizing epitopes generated by acetaldehyde and malonildialdehyde. However, competitive inhibition experiments indicated that the anti-MAA antibodies were unrelated to those against acetaldehyde- or malonildialdehyde-derived antigens and mainly recognized a specific, cyclic MAA epitope. Some degree of immune reactivity towards MAA adducts was also observed in patients with non-alcohol-induced liver injury. However, competitive ELISA showed that the antigens recognized by these sera were not the cyclic MAA adducts. Altogether, these results showed the formation of MAA antigens during alcohol-induced liver disease and suggest their possible contribution to the development of immunologic reactions associated with alcohol-related liver damage.

Effect of adrenalectomy on ethanol-associated changes in lymphocyte cell numbers and subpopulations in thymus, spleen, and gut-associated lymphoid tissues

Consumption of ethanol (ETOH) by experimental animals and human beings is associated with elevated serum levels of corticosteroids. One of the most robust findings associated with ETOH consumption is a loss of lymphocytes from thymus and spleen, as well as from peripheral lymphoid organs to include mesenteric lymph nodes and Peyer's patches, which are lymphoid organs associated with the gastrointestinal tract. To study the role of corticosteroids in loss of cells from thymus, spleen, and gut-associated lymphoid organs, adrenalectomized (ADX) or intact C57Bl/6 mice were fed a liquid diet containing ETOH (to supply 36% of calories as ETOH) or an isocaloric control diet with a pair-feeding protocol. Loss of lymphocytes from all lymphoid organs was associated closely with serum corticosterone levels in both ETOH-fed and pair-fed groups. ETOH-fed ADX animals showed much less cell loss than did ETOH-fed intact animals. However, there was still an association between ETOH consumption and cell loss when cell loss in ETOH-fed ADX animals was compared with that in ADX pair-fed and ADX chow-fed groups. In both intact and ADX animals ETOH consumption was associated with a loss of immature (CD4(+) and CD8(+)) cells from the thymus. These data lead to the suggestion that corticosteroids are responsible for most of the cell loss from thymus, spleen, mesenteric lymph nodes, and Peyer's patches in association with ETOH consumption. Some cell loss, however, is independent of corticosteroids. The data presented here also support the suggestion that cell loss from lymphoid organs could be the result of nutritional factors.

Alcohol abuse, alcoholism, and damage to the immune system--a review

Chronic alcohol abuse exacts a major social and medical toll in the United States and other Western countries. One of the least appreciated medical complications of alcohol abuse is altered immune regulation leading to immunodeficiency and autoimmunity. The consequences of the immunodeficiency include increased susceptibility to bacterial pneumonia, tuberculosis, and other infectious diseases. In addition, the chronic alcoholic often has circulating autoantibodies, and recent investigations indicate that the most destructive complications of alcoholism, such as liver disease and liver failure, may have a component of autoimmunity. Current research on altered cytokine balance produced by alcohol is leading to new insights on the regulation of the immune system in the chronic alcoholic. There is also recent development of exciting new techniques designed to improve or restore immune function by manipulation of cytokine balance. Although much remains to be learned, both in the abnormalities produced by alcohol and in the techniques to reverse those abnormalities, current progress reflects a rapidly improving understanding of the basic immune disorders of the alcoholic.

Soluble proteins modified with acetaldehyde and malondialdehyde are immunogenic in the absence of adjuvant

Recent studies have shown that the alcohol metabolites malondialdehyde and acetaldehyde can combine to form a stable adduct (MAA) on proteins. This adduct has been detected in the livers of rats chronically consuming ethanol, and serum antibodies to MAA have been observed at significantly higher concentrations in ethanol-fed when compared with pair-fed or chow-fed control rats. More recently, preliminary studies have strongly suggested that the MAA adduct is capable of stimulating antibody responses to soluble proteins in the absence of adjuvants. The antibodies produced recognize either the MAA epitope or the carrier protein itself. Therefore, it was the purpose of this study to examine the potential immunogenicity of MAA-modified exogenous proteins in the absence of adjuvants. Balb/c mice were immunized in the presence or absence of adjuvant with different concentrations of unmodified or MAA-modified proteins. The antibody response to both the MAA epitope and unmodified protein epitopes were determined by ELISA. In the absence of adjuvant, significant antibody responses were induced to both the MAA epitope and nonmodified protein epitopes. Smaller immunizing doses of MAA-protein conjugate favored the production of antibodies to nonmodified proteins, whereas larger doses induced a strong anti-MAA response. In studies to begin determining a mechanism for the specificity of the response in the absence of adjuvants, peritoneal macrophages were found to bind and degrade MAA-adducted proteins through the use of a scavenger receptor. This indicated that MAA-adducted proteins may be specifically taken up and epitopes presented to the humoral immune system in the absence of adjuvants. Importantly, these are the first data showing that an alcohol-related metabolite can induce an antibody response in the absence of adjuvant and suggesting a mechanism by which antibody to the MAA adduct or its carrier (exogenous or endogenous) proteins may be generated in vivo.

Effects of exogenous cytokines on the ethanol-mediated suppression of murine thymocyte proliferation

Although attempts have been made to assess the effect of ethanol on murine thymocyte proliferation, the mechanism which accounts for the immunosuppressive effect of ethanol on the thymocyte proliferation has not been elucidated. Thus, a mouse model was used to determine (1) whether there is a similarity in the effect of ethanol exposure in vitro and in vivo on the proliferative response of thymocytes to phytohemagglutinin (PHA), (2) whether ethanol exposure affects the responsiveness of thymocytes to exogenous interleukin (IL)-1 and IL-2, and (3) whether ethanol affects IL-1 production by peritoneal macrophages. We found that the proliferative response of thymocytes from mice fed on an ethanol-containing diet was significantly inhibited (P < 0.05) compared to that in mice fed on maltose or standard diets. We also observed that low concentrations of ethanol (12.5 mM) appeared to enhance the mitogenic response of thymocytes to PHA, but the response was not significantly greater than that of controls (P > 0.05). Ethanol at higher concentrations (25-100 mM) significantly suppressed the mitogenic response of thymocytes to PHA (P < 0.05) in a dose-dependent manner. Our data also revealed that (1) ethanol did not significantly suppress IL-1 secretion by adherent macrophages stimulated by LPS, and (2) the addition of exogenous IL-1 was insufficient to restore full responsiveness in thymocytes from ethanol-fed mice. Taken together, these results suggest that the suppressive effect of ethanol on thymocyte proliferation is not mediated by insufficient IL-1. Finally, we present novel evidence that addition of exogenous IL-2 completely restores the impaired proliferative response of thymocytes from ethanol-fed mice to control levels. In summary, our results demonstrate that ethanol inhibits thymocyte proliferation in response to PHA, and that the inhibition is not due to insufficient IL-1. We also report that addition of exogenous IL-2 is sufficient to restore full proliferative capacity to thymocytes from ethanol-fed mice.

Alcohol inhibits cell mitosis in G2-M phase in cell cycle in a human lymphocytes in vitro study

Alcohol abuse is associated with the loss of immunocompetence, which leads to decreasing resistance to infections. No single mechanism can be accountable for the detrimental effects of alcohol on the body's defense mechanism. We present data demonstrating that, in cultured lymphocytes, 10-40 mM alcohol in the media caused 18-90% decrease in cell mitosis (p < 0.001). There was a linear decrease in cell mitosis upto 40 mM alcohol; at 100 mM cell mitosis virtually ceased. This study aimed to determine in which phase of the cell cycle did alcohol mediate its effects. The results showed that DNA synthesis was not affected with up to 50 mM alcohol, suggesting that G1-S phase in the cell cycle remained unaffected. At 100 mM alcohol, DNA synthesis decreased significantly (p < 0.01). From the results of this study, we conclude that a subpharmacological dose level of alcohol (10 mM) significantly inhibited cell mitosis and the inhibitory effect of alcohol was mediated in the G2-M phase in the cell cycle. The G1-S phase was unaffected.

Modulation of T-cell adhesion markers, and the CD45R and CD57 antigens in human alcoholics

Direct and indirect evidence indicates that T cells are altered in alcoholics. The most commonly reported changes under direct examination have been consistent with an increased level of activation as reflected by shifts in the ratio of common leukocyte antigen isoforms expressed at the cell surface, by increases in the expression of class II antigen, or by alterations in the expression of various adhesion molecules. Functional evidence for T-cell abnormality includes loss of delayed hypersensitivity and a number of findings attributed to dysregulation of B cells by alcoholic T cells; these include the widely reported distrubances of immunoglobulin production in vivo and a range of abnormal responses when T and B cells are combined in vitro. Detailed flow cytometric examination of T cells from alcoholics with or without active liver disease reveals a significant loss of L-selectin CD8+ T cells, but not usually of CD4+ T cells. There is an inverse increase in the expression of CD11b on the CD8+ cells that have decreased L-selectin+ percentages. Both CD8+ and CD4+ T cells in alcoholics display a significant loss of the CD45RA isoform and a gain of cells exhibiting the CD45RO isoform. Other surface alterations include increased expression of CD57, a marker most commonly associated on T cells with conditions of chronic increased antigenic exposure. It is argued that these and other T-cell alterations in alcoholics are cytokine-driven in part and result in T-cell differentiation states that are functionally inappropriate.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaldehyde-serum protein adducts inhibit interleukin-2 secretion in concanavalin A-stimulated murine splenocytes: a potential common pathway for ethanol-induced immunomodulation

Variable immunobiological changes occur with alcohol consumption. Previous studies have shown that acetaldehyde forms stable adducts with serum proteins, including albumin. These adducts are elevated in persons and animals consuming ethanol. We examined the effect of serum protein-acetaldehyde adducts formed with fetal bovine serum (FBS) on concanavalin A-stimulated murine splenocytes. Interleukin-2 (IL-2) secretion and IL-2 receptor (IL-2R) expression were determined as a function of the effect of the acetaldehyde-protein adduct(s). FBS was incubated with acetaldehyde (500, 100, 50, 25, 10, and 0 microM) for 1 hr at 37 degrees C. Excess acetaldehyde was removed by ultrafiltration using a 500 molecular weight cut-off membrane in 3 volumes. Free as well as bound acetaldehyde was quantified using fluorigenic HPLC before and after incubation. Recovered acetaldehyde correlated with the amount added (r2 = 0.996). Splenocytes were cultured for 48 hr in complete medium containing 5% acetaldehyde-treated and 5% untreated FBS with 4 micrograms/ml concanavalin A. Although cell viability was unchanged, acetaldehyde-treated FBS mixed with native FBS decreased IL-2 secretion in a dose-dependent manner. The percentage of cells expressing IL-2R was reduced only at the highest acetaldehyde-FBS dose. Therefore, immunological effects ascribed to ethanol may result in part from the toxic properties of acetaldehyde-protein adducts on IL-2 secretion.

Detection of reduced acetaldehyde protein adducts using a unique monoclonal antibody

Acetaldehyde (AA), the major product of alcohol metabolism, has been shown to bind to proteins in vivo and form chemical adducts. These AA-protein adducts have been shown to alter protein structure and function and may result in tissue damage. Recent reports have shown that polyclonal antibodies can be produced that recognize proteins modified in vitro with AA in the presence of sodium cyanoborohydride (NaCNBH3), a strong reducing (R) agent. Antibodies prepared in this way have been shown to recognize proteins in the livers of rats fed alcohol chronically. Because multiple AA-protein adducts can be recognized by polyclonal antisera, and a variety of adducts may be formed in vitro or in vivo, this study was designed to develop monoclonal antibodies specific for proteins modified by AA. In addition, adducts formed under R conditions are probably chemically different than those formed under nonreducing (NR) conditions, and monoclonal antibodies may provide the specificity required to distinguish these chemical differences. Balb/c mice were immunized with bovine brain tubulin that was modified by treatment with 5 mM AA for 7 days under NR conditions. Sera from immunized animals were tested for antibody activity to the immunogen (protein-NR) and for cross-reactivity to protein-R and unmodified protein. Although the highest serum antibody titers were seen toward the NR adduct, antibodies to the R adduct were also detected. This activity difference was independent of the carrier protein, because NR and R bovine serum albumin, keyhole limpet hemocyanin, and actin also gave similar results when used as the adducted protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-6 and interleukin-8 production by mononuclear cells of chronic alcoholics during treatment

Chronic alcohol consumption has been associated with suppression of a number of immune parameters. This study was designed to investigate the relationship between chronic alcohol ingestion and cessation with respect to release of interleukin-6 (IL-6) and interleukin-8 (IL-8) using highly specific and sensitive ELISA assays, as well as a functional assay, natural killer cell cytotoxic activity. ELISAs were developed to determine the amount of IL-6 and IL-8 release by peripheral blood mononuclear cells (PBMCs). Two groups of subjects were recruited: young (18-22 years old), nonalcoholic users (controls) and long-term alcoholics (35-55 years old). Blood samples were collected at time 0 from all subjects and from alcoholics 28 days after treatment had begun and alcohol use had ceased. Then mitogen-stimulated release of cytokines by peripheral blood cells was determined. The abstaining controls, and the alcoholics, after 30 days of abstinence, tended to produce lower amounts of IL-6 and IL-8, although these differences were not statistically significant. Natural killer cell activity was not statistically different between the young groups, yet appeared to increase once alcohol use discontinued. Some of the cells from the controls (abstainers) were incubated with ethanol (EtOH). Its content in sealed wells was measured after the time of incubation of PBMCs. When EtOH was serially diluted in plates, some well-well diffusion was noted, but the maximum concentration of EtOH never fell below 0.3% from an initial concentration of 0.5%, and at no time was the EtOH concentration gradient completely lost, even after 66 hr of incubation.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired cytosolic free calcium response in splenic T-cells from mice fed with ethanol-containing diet

Calcium-dependent signal transduction pathways of T-cell proliferation have been extensively studied in the past years. However, little is known about effects of ethanol on the calcium-dependent signal transduction pathway in T-cell proliferation. Thus, a murine model was used to determine effects of ethanol in vivo on T-cell proliferation and the intracellular free calcium concentration [Ca2+]i in response to Concanavalin A (Con A) and recombinant IL2 (rIL2) in T-cells. Splenic cells from young C57BL/6 mice, that had been fed on 3 different diets (ethanol-, maltose substitute- and standard liquid-diet) for 7-8 weeks were tested for their proliferative responses to Con A and rIL2. Concurrently, measurement was also made of [Ca2+]i in the nylon-wool-enriched resting T-cells induced by Con A and in Con-A-activated blast T-cells induced by rIL2. Our results showed that [Ca2+]i increases were seen in the splenic T-cells from three different groups of mice following Con A, but not rIL2 stimulation. However, this increase was much smaller in the splenic T-cells from ethanol-fed mice as compared to mice on maltose- or standard-diet. Furthermore, we also demonstrated that the impaired [Ca2+]i increase was seen in the T-cells of the same ethanol-fed mice having decreased the proliferative response to Con A. This reduced proliferation did not result from the presence of excessive suppressor T-cell activity. Finally, we also demonstrated that both the number of IL2 binding sites/cell and the Kd values of the low- and high-affinity IL2R on the T-cells from ethanol-fed mice were unaltered. Because evidence indicates that (1) a normal level of [Ca2+]i increase is a prerequisite for the production of IL2 by mitogen-stimulated T-cells, and (2) T-cells from ethanol-fed mice have normal capacities to produce IL2 that is the crucial growth factor controlling T-cells to progress through the cell cycle, these lines of evidence taken together with the results of this study suggest that the impairment in [Ca2+]i increases in T-cells from ethanol-fed mice may not be the primary factor contributing to the diminished T-cell proliferation in the same mice.

The influence of age on blood alcohol levels and ethanol-associated immunosuppression in a murine model of ethanol consumption

Several study findings indicate that with ethanol ingestion a number of changes occur in the immune system. We studied the effects of ethanol consumption on mice at various ages. We used a murine model in which young (age 6-8 weeks), middle-aged (age 12 months), and old (age 24 months) male C57Bl/6 mice were pair-fed either a Leiber-DeCarli liquid diet containing 7% (v/v) ethanol or an isocaloric control diet. Consumption of ethanol diet for 8 days resulted in high blood alcohol levels in young and old mice; low levels were observed in middle-aged mice. Middle-aged mice consumed more ethanol than did either young or old mice and had the lowest percent body weight loss of all three age groups. Proliferation of spleen lymphocytes to T-cell stimuli (concanavalin A and alloantigens) in both young and old mice fed ethanol was diminished. T-cell function was unchanged in middle-aged mice consuming an ethanol diet when compared with that observed in age-matched mice pair-fed control diet. No effect of ethanol on proliferation to lipopolysaccharide was noted in any group. Proliferative response of T cells to soluble anti-CD3 monoclonal antibody was also decreased in middle-aged and old pair-fed control mice when compared with young control mice. The proliferative response to soluble anti-CD3 in all three age groups of mice fed ethanol, however, was not significantly affected by ethanol consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral trauma and alcohol abuse

We report results of clinical examinations, computed tomography, quantitative electroencephalography (QEEG), and cerebral blood flow measurements performed on a series of 56 consecutive brain injury patients including 15 alcohol abusers and 41 non-alcoholic subjects. Greater volumes of intracranial haemorrhage were noted in the alcoholics for a similar severity of injury and local brain atrophy became more pronounced in them during a follow-up of 1 year. After this time, the third ventricle width, distance between frontal horns, the sum of lateral ventricle dimensions and cortical sulci were all markedly larger in the alcoholics. The QEEG results also indicated a weaker improvement in the alcoholics. The cerebral blood flow at the site of the injury was initially slow in the alcoholics when compared to the contralateral region of the other hemisphere, although these differences disappeared during the follow-up. Permanent occupational disability was also found to be associated with pretraumatic alcohol abuse. The findings indicate that ethanol abuse is not only commonly associated with cerebral trauma but is also a risk factor for a more severe brain damage following the injury.

Mucosal immune dysfunction associated with alcoholic IgA nephropathy

We investigated the hypothesis that alcohol-induced changes of the immune system result in IgA nephropathy (IAN). Wistar rats were infused with liquid diet containing alcohol: "alcoholics." Control rats received an isocaloric diet with glucose instead of alcohol. IAN was diagnosed by mesangial IgA deposition. When compared to controls, serum IgA in alcoholic rats with IAN had a fourfold increase and a twofold increase in alcoholics without IAN. The intestinal lamina propria showed overall lymphocyte depletion in alcoholic rats. The decrease was not uniform for all the lymphocyte subgroups: it resulted in a relative increase in IgA-B cells in alcoholic rats with IAN but not in alcoholic rats without IAN. No significant differences were observed between alcoholic and control rats in the percentages of spleen lymphocyte subtypes. We suggest that dysfunction of the mucosal immune system may be related to the induction of IAN in chronic alcohol consumption.

Alterations in brain polyribosomal RNA translation and lymphocyte proliferation in prenatal ethanol-exposed rats

The long-term effects of prenatal ethanol exposure on the properties of brain polysomes and the proliferative responses of lymphocytes to mitogenic stimulation in adult offspring were assessed. Female Sprague-Dawley rats either ingested the control or 6.6% ethanol-containing Lieber-DeCarli liquid diet during the 3rd trimester of pregnancy. Controls were age-matched and pair-fed. At 42 to 72 days of age, ethanol effects were evaluated on the (1) polysomal properties in the cerebral hemispheres, cerebellum, and hippocampal regions of the brain after translation in a messenger RNA (mRNA)-dependent rabbit reticulocyte lysate system and (2) immunologic functions of lymphocytes cultured from spleen cells by measuring their responses to mitogenic stimulation. Results showed long-term adverse effects of in utero ethanol exposure on the polysomal RNA translation in each of the three brain regions tested with free polysomal mRNAs affected more than the bound polysomal mRNAs. Of these, the hippocampal region appeared to sustain the most injurious effects. In addition, a suppression of the mitogen-induced lymphocyte proliferative responses were present under these conditions. The degree of suppression varied with the specific mitogen used. Data suggest that the ethanol effects on the CNS and lymphocyte proliferation are most possibly irreversible, and in the case of the CNS, a post-translational modification by ethanol is indicated. The reduced lymphocyte responses are suggestive of a possible interference by ethanol of the synthesis of interleukin-2 (IL-2) and/or a reduced binding of IL-2 with its receptor (IL-2 receptors).

[The relationship between paracoccidioidomycosis and alcoholism]

The relationship between alcoholism and paracoccidioidomycosis was evaluated by the case-control method. The alcohol consumption of 4 groups of patients was compared: 50 patients with chronic paracoccidioidomycosis, 20 patients with the acute or subacute form of this mycosis and their respective control groups of hospitalized patients, each case matched by sex and age. Between September 1986 and July 1988 the cases and their controls were interviewed by one and the same investigator using a questionnaire on drinking habits: quantity and type of beverage consumed, time of onset and frequency of use and whether they had manifested symptoms of inebriation or of alcohol dependence previously. As compared with control patients, the mean daily ingestion of alcohol in excess of 60 ml was more frequent in the chronic paracoccidioidomycosis group (50.0% x 30.0%). These patients also preferred to drink sugar cane brandy more frequently (89.4% x 68.3%). When the average daily consumption of ethyl alcohol exceeded 100 ml, most patients presented a recurrence of infection during or after antifungal therapy. In the acute-subacute paracoccidioidomycosis group, 64.3% of the patients reported inebriation on one or more occasions, versus 17.6% in the respective control group. The results suggest that alcoholism can be a predisposing factor to paracoccidioidomycosis and, probably, accounts for a worse prognosis for this infection.

Cellular intermediate filament networks and their derangement in alcoholic hepatitis

Intermediate filaments are major components of most eukaryotic cells that form from the polymerization of protein subunits that are expressed in tissue and development specific fashions. The interactions of intermediate filaments with a myriad of other cellular proteins and structures give rise to a complex overall cellular architecture that is likely responsible for cellular well-being. The mature 10-nm filaments are relatively stable cellular structures, but the intermediate filaments undergo major morphological and biochemical changes, especially during mitosis, differentiation, and in response to certain drugs. Evidence exists that hepatocyte intermediate filaments (keratin filaments) are deranged in alcoholic hepatitis, an inflammatory liver disease of alcoholics and heavy spree drinkers. The classical and characteristic pathological hepatocyte inclusion bodies of alcoholic hepatitis, Mallory bodies, are composed in part of normal keratins that likely derive from the pre-existing hepatocyte intermediate filament network. It is unclear if intermediate filament network derangement in alcoholic hepatitis is directly caused by the actions of ethanol or its metabolites on intermediate filaments or their associated structures, or whether alcohol causes a cellular insult or injury elsewhere and a subsequent response (e.g., immune) causes intermediate filament network derangement. The precise mechanisms responsible for intermediate filament derangement remain to be elucidated; however, experimental data exist that support and refute several hypotheses. Hopefully, further studies will help determine a better overall understanding of the abnormalities of intermediate filaments and their relationship to the pathophysiology of alcoholic hepatitis and other diseases.

The generation of cytotoxic T lymphocytes against acetaldehyde-modified syngeneic cells

The major metabolic product of ethanol is acetaldehyde. It is highly reactive with proteins. In situ this modification is significant enough to generate an antibody response. Whether an effector cellular immune response can be generated against these acetaldehyde modified adducts on syngeneic cells is not known. In this paper we have demonstrated in the murine system that acetaldehyde modified splenic cells can generate cytotoxic T lymphocytes (CTL). These CTL are specific for the acetaldehyde modified syngeneic cells, and not acetaldehyde modified allogeneic cells. The ability of the CTL to lyse-specific targets is dependent on the formation of stable acetaldehyde adducts. Cold target inhibition studies reveal that modified syngeneic cells can inhibit lysis as effectively as unmodified cells. Therefore, the present study lends support to the hypothesis that acetaldehyde modified cells can generate a cellular immune response and may do so in pathologic states.

Alcohol withdrawal syndrome--an auto-immune disease? A neuroimmunologic model for pathogenesis of alcohol withdrawal symptoms

A neuroimmunologic model of alcohol withdrawal symptoms is developed according to which these may be considered as an idiopathic auto-immune disease. During the alcohol abuse period of non-addicts, homeostasis may alter pathologically by gradual adaptation of the organism: auto-sensitisation develops and finally leads to the breakdown of auto-immune tolerance of the structural modifications set by alcohol withdrawal. The immunosystem regards the existing assimilation of alcohol as self, the withdrawal of alcohol as non-self. Alcohol withdrawal may be considered as an acknowledged physical stressor, and physical stressors as potential triggers of auto-immune diseases. Some so-called alcohol-induced diseases may originate in the pathogenic effects of preceding auto-immune responses to repeated alcohol withdrawals. Neuroimmunologic preconditions of potential auto-immune diseases exactly fit the alcohol withdrawal situation. Neuroimmunologic diseases themselves show close analogies respectively to alcohol withdrawal symptoms as well as to some alcohol-induced diseases. The myelin basis protein is assumed to be a potential auto-allergen. Finally withdrawal symptoms being the expression of physical dependence on alcohol, the model may highlight the very nature of physical dependence.

Immunotoxicity of alcohol in young and old mice. I. In vitro suppressive effects of ethanol on the activities of T and B immune cells of aging mice

A murine aging model was employed to assess effects of ethanol exposure on the T-cell proliferative response to mitogenic stimulation and on the T cell-dependent primary antibody response to sheep red blood cells (RBC) in vitro. Splenic cells from young (3-5 months) and old (28-32 months) BALB/c mice were first assessed for their ability to produce interleukin (IL) 2 and proliferate in response to mitogenic stimulation in the presence of various doses of ethanol. Then, splenic T blast cells from young and old mice, generated by Con A-activation, were assessed for their IL2-dependent proliferative capacity in the presence of various doses of ethanol. Finally, splenic cells of young and old mice were assessed for their ability to generate plaque-forming cells (PFC) in response to sheep RBC in the presence of various doses of ethanol. The results revealed that ethanol has a much greater suppressive effect on old than young splenic T cells (10-15 times), as judged by their ability to proliferate in response to mitogenic stimulation. However, the magnitude of the difference in the suppressive effect is less when the cells are cycling (2 times). Furthermore, ethanol had only a minimal suppressive effect on IL2 production by T cells of both young and old mice, even at the concentration of 100 mM. These findings would suggest that the ethanol-mediated suppression of T cell proliferation of both young and old mice is more likely due to an impairment of metabolic event(s) associated with or subsequent to the interaction of IL2 and IL2 receptor leading to cellular replication.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of ethanol in vitro on some parameters of the immune response

The action of ethanol (ETH) on murine lymphocyte subpopulations and on human peripheral blood mononuclear cells (PBMC) stimulated in vitro by mitogens was studied. ETH caused a concentration-dependent decrease in DNA synthesis in the different murine cell types. ETH was more immunosuppressive for T lymphocytes than for B lymphocytes. An enhancement of the blastogenic response was observed for B cells at 0.5% ETH. Interleukin 2 synthesis by murine splenocytes was inhibited by ETH in a concentration-related manner; the lowest concentrations of ETH caused an increase in interleukin 2 synthesis. The highest concentrations of ETH tested decreased the size of the cell clusters formed in cultures of mitogen-stimulated lymphocytes, whereas an increase in PBMC cluster size was observed in the presence of 0.5 and 1% ETH.

Hematological complications of alcoholism

Numerous clinical observations support the notion that ethanol has multiple pathologic effects on hematopoietic tissue. The effects of alcohol on blood are diverse. The long-term ingestion of large quantities of ethanol has been shown to alter a substantial number of physiologic and biochemical variables. Abnormalities involving leukocytes, platelets, and erythrocytes may occur singly or in various combinations. Due to the frequent concomitant presence of alcohol-related hepatic disease, nutritional deficiencies, infection, and other chronic diseases, it is often difficult to distinguish the specific hematologic toxicities of alcohol ingestion from the hematologic toxicities of associated morbid conditions. Depressed hematopoietic cell formation (Table 2), increased destruction, and alterations in morphology and function of hematopoietic cells have been described.

Interferon-associated lymphocyte 2',5'-oligoadenylate synthetase in acute and chronic viral hepatitis

Basal levels of the interferon-associated enzyme 2',5'-oligoadenylate synthetase were studied in lymphocytes of 46 patients with acute viral hepatitis and in 46 patients with chronic hepatitis B. Measurement of in vitro production of 2',5'-oligoadenylate synthetase following overnight incubation of lymphocytes with exogenous interferon was used to assess functional capacity of the lymphocyte interferon system. In acute hepatitis patients, an early but transient elevation of 2',5'-oligoadenylate synthetase was observed; the mean level at 1 week was significantly greater than the mean level at 4 weeks after the onset of their illness (p less than 0.01). Serial 2',5'-oligoadenylate synthetase levels did not identify those patients who were to progress to chronic hepatitis. Patients with chronic hepatitis B infection, regardless of background liver histology, generally had normal basal lymphocyte 2',5'-oligoadenylate synthetase levels. In both acute viral hepatitis and chronic hepatitis B, there was an inverse correlation between basal 2',5'-oligoadenylate synthetase level and 2',5'-oligoadenylate synthetase response to overnight incubation with interferon, a finding that suggested a transient down-regulation of interferon responsiveness. These findings provided no support for the hypothesis that there is an inherent or persistently induced deficiency in the interferon system in acute or chronic hepatitis B.

Alcohol, cancer, and immunomodulation

There is a great deal of epidemiological evidence indicating that chronic, excessive alcohol consumption is a major risk factor for cancers in humans. However, the experimental basis for the increased cancer risk associated with alcohol intake is not clear. Since it appears that ethanol alone is not carcinogenic, ethanol effects must be explained in terms of its modifying the actions of other causal agents. Current studies indicate that ethanol and its congeners may act as tumor promoters, thereby enhancing the effect of initiating carcinogens from the environment. Available evidence also shows that ethanol is immunosuppressive. Clearly, cirrhosis due to high, prolonged alcohol intake is an indicator of the immunosuppressive effects of ethanol. It is less clear that more moderate intakes of alcohol could have as profound an effect on immune systems. However, changes do occur yielding alterations in lymphocyte sensitivity to alcohol in vitro and in cell development, as shown by increased NK cell function at low concentrations. Since other conditions, such as cytotoxic drugs which suppress cellular immune functions, are clearly associated with increased cancer risk. It is intriguing to think that prolonged exposure to ethanol-induced immunosuppression may be a cofactor in the promotion of cancer. The tumor promotion may take place via a variety of mechanisms as discussed in this paper, including reduced host defenses by direct effects of ethanol, its metabolites, and/or malnutrition. It may be beneficial to test methods for immunostimulation in prolonged alcohol abusers, where cessation of use is unsuccessful or residual immunosuppression remains, to reduce the risk of development or growth of initiated tumors.

Functional and numerical alterations induced by ethanol in the cellular immune system

Ethanol was found to alter functioning and numbers of lymphoid cells of the cellular immune system in humans and rats. In in-vitro studies on human lymphocytes, a higher than 0.1% concentration of ethanol and acetaldehyde and acetic acid, the metabolites of ethanol, caused a decrease in the formation of E-rosettes. Methanol and propanol also resulted in a decrease in E-rosette formation. The natural killer (NK) cells varied in their ability to lyse tumor cells. In vitro, the NK-cell activity declined at higher than 0.2% concentration of ethanol. The NK activity in cells isolated from spleen and thymus of rats fed 1 g/dl or 7 g/dl ethanol did not differ significantly from the controls. Sprague Dawley rats fed 1 g/dl or 7 g/dl ethanol for 12 weeks had a significantly smaller thymus compared to the controls. Alveolar macrophages isolated from the rats exhibited impaired phagocytic activity. In agreement with other investigators, ethanol was found to result in a loss of T-cell population in the spleens of rats fed ethanol for 13 months. On the other hand, the T-helper cells and the proportion of T-helper to T-suppressor cells were found to increase in the splenocytes from these rats. This latter occurrence, apparently, is to compensate for the general loss of T-cell population observed in the body that occurs with ethanol ingestion. It is hypothesized that immunosuppression and the transient imbalances in the components of the cellular immunity induced by ethanol lead to an increased risk of pathogenesis associated with alcohol consumption.

Imparied lymphocyte proliferative response to mitogen in alcoholic patients. Absence of a relation to liver disease activity

Concanavalin A-induced lymphocyte proliferation was studied in 25 patients with alcoholic hepatitis or compensated alcoholic cirrhosis. Nine alcoholics without evidence of liver disease were also evaluated. A nonlinear correlation equation, which was natural logarithmic, was applied to individual dose-response proliferation curves and permitted comparisons between patient groups and controls. The proliferative response in all patient groups was significantly lower when compared to healthy controls and was independent of the presence or absence of liver disease. This suggests that some changes in immune function observed in alcoholics may be linked to the direct effects of alcohol on the immune system rather than to the associated liver disease.

Antibodies against acetaldehyde-modified protein epitopes in human alcoholics

Acetaldehyde, the primary metabolite of ethanol, binds covalently to proteins forming condensation products which have been recently shown to be immunogenic. To assess whether an antibody response against acetaldehyde-modified protein epitopes is associated with alcoholic liver disease, the serum immunoreactivity against proteins modified in vitro by acetaldehyde and against the corresponding unmodified proteins was measured by an enzyme-linked immunosorbent assay in 58 alcoholics with varying degrees of liver damage. Alcoholics showed significantly higher titers against protein-acetaldehyde conjugates than against the unmodified protein, independent of the nature of the carrier protein. The highest titers occurred in alcoholic hepatitis patients. Sera of patients with chronic hepatitis of nonalcoholic origin and of healthy controls also reacted with acetaldehyde conjugates, but their titers were significantly lower than those in alcoholic hepatitis patients. Our data support the idea that binding of acetaldehyde to proteins in humans generates antigenic determinants which trigger a corresponding immune response against such epitopes and suggest that this humoral immune response may be implicated in autoantibody formation and liver damage associated with excessive alcohol consumption.

Sensitivity of human lymphocytes to acetaldehyde: comparison between alcoholic and control subjects

The action of acetaldehyde (ACH), the first metabolite of ethanol, was studied on human lymphocytes stimulated in vitro by phytohemagglutinin (PHA) or Concanavalin A (Con A). ACH caused a dose-dependent decrease of [3H]thymidine uptake in lymphocytes from both alcoholic and control subjects. The area under the curve of [3H]thymidine incorporation as a function of ACH concentration was determined for each subject and referred to as the lymphocyte sensitivity index. Indexes for alcoholic subjects were found to be higher than those for controls, indicating a lower sensitivity to ACH of lymphocytes from alcoholics. We also found a wide range of sensitivity indexes within the same group. These results are consistent with the current hypothesis that not everybody is at equal risk to develop alcohol related disorders.