Alcohol modulates alveolar macrophage tumor necrosis factor-alpha, superoxide anion, and nitric oxide secretion in the rat

Ethanol Consumption Induces Nonspecific Inflammation and Functional Defects in Alveolar Macrophages

Chronic alcohol drinking is associated with increased susceptibility to viral and bacterial respiratory pathogens. In this study, we use a rhesus macaque model of voluntary ethanol self-administration to study the effects of long-term alcohol drinking on the immunological landscape of the lung. We report a heightened inflammatory state in alveolar macrophages (AMs) obtained from ethanol (EtOH)-drinking animals that is accompanied by increased chromatin accessibility in intergenic regions that regulate inflammatory genes and contain binding motifs for transcription factors AP-1, IRF8, and NFKB p-65. In line with these transcriptional and epigenetic changes at the basal state, AMs from EtOH-drinking animals generate elevated inflammatory mediator responses to lipopolysaccharides and respiratory syncytial virus. However, the transcriptional analysis revealed an inefficient induction of interferon-stimulated genes with EtOH in response to the respiratory syncytial virus, suggesting disruption of antimicrobial defenses. Correspondingly, AMs from EtOH-drinking animals exhibited transcriptional shifts indicative of increased oxidative stress and oxidative phosphorylation, which was coupled with higher cytosolic reactive oxygen species and mitochondrial potential. This heightened oxidative stress state was accompanied by decreased ability to phagocytose bacteria. Bulk RNA and assay for transposase-accessible chromatin sequencing data further revealed reduced expression and chromatin accessibility of loci associated with tissue repair and maintenance with chronic EtOH drinking. Similarly, analysis of single-cell RNA sequencing data revealed shifts in cell states from tissue maintenance to inflammatory responses with EtOH. Collectively, these data provide novel insight into mechanisms by which chronic EtOH drinking increases susceptibility to infection in patients with alcohol use disorders.

Transcriptional and Epigenetic Regulation of Monocyte and Macrophage Dysfunction by Chronic Alcohol Consumption

Drinking alcohol, even in moderation, can affect the immune system. Studies have shown disproportionate effects of alcohol on circulating and tissue-resident myeloid cells (granulocytes, monocytes, macrophages, dendritic cells). These cells orchestrate the body's first line of defense against microbial challenges as well as maintain tissue homeostasis and repair. Alcohol's effects on these cells are dependent on exposure pattern, with acute drinking dampening but chronic drinking enhancing production of inflammatory mediators. Although chronic drinking is associated with heightened systemic inflammation, studies on tissue resident macrophage populations in several organs including the spleen, liver, brain, and lung have also shown compromised functional and metabolic capacities of these cells. Many of these effects are thought to be mediated by oxidative stress caused by alcohol and its metabolites which can directly impact the cellular epigenetic landscapes. In addition, since myeloid cells are relatively short-lived in circulation and are under constant repopulation from the bone marrow compartment, alcohol's effects on bone marrow progenitors and hematopoiesis are important for understanding the impact of alcohol systemically on these myeloid populations. Alcohol-induced disruption of progenitor, circulating, and tissue resident myeloid populations contribute to the increased susceptibility of patients with alcohol use disorders to viral and bacterial infections. In this review, we provide an overview of the impact of chronic alcohol consumption on the function of monocytes and macrophages in host defense, tissue repair and inflammation. We then summarize our current understanding of the mechanisms underlying alcohol-induced disruption and examine changes in transcriptome and epigenome of monocytes and mcrophages. Overall, chronic alcohol consumption leads to hyper-inflammation concomitant with decreased microbial and wound healing responses by monocytes/macrophages due to a rewiring of the epigentic and transcriptional landscape. However, in advanced alcoholic liver disease, myeloid cells become immunosuppressed as a response to the surrounding hyper-inflammatory milieu. Therefore, the effect of chronic alcohol on the inflammatory response depends on disease state and the immune cell population.

Ethanol modulates the effector functions of human monocyte-derived macrophages in response to Paracoccidioides brasiliensis yeast cells

We aimed to investigate the effects of ethanol and its metabolites (β-hydroxybutyrate and sodium acetate) in the effector functions of macrophages in response to Paracoccidioides brasiliensis yeast cells and to determine their influence in the development of the adaptive response. Purified peripheral blood monocytes were differentiated into macrophages and were treated with ethanol, β-hydroxybutyrate, and sodium acetate, and stimulated with P. brasiliensis yeast cells and evaluated for their phenotypic characteristics, functional activity, and capability to induce T cells activation/differentiation. We found that the ethanol treatment diminished the expression of HLA-AB, HLA-DR, CD80, and CD86, modulating the expression of dectin-1, as well as Syk phosphorylation. The ethanol treatment increased the phagocytic activity, expression of CD206, and IL-10 production; however, reduced ROS production, fungicidal activity, caspase-1 cleavage, and IL-1β and IL-6 production. Our data also showed that the presence of ethanol reduced the differentiation of Th1 and Th17 cells and increased the frequency of Th2 cells. Our results indicated that ethanol exposure could suppress effector function of macrophages, possibly leading to the polarization of M2 macrophages. The ethanol modulates the expression of costimulatory and antigen-presentation molecules and interferes with the NLRP3 inflammasome. Altogether, these alterations affect the development of the adaptive response, decreasing the frequency of IL-17, IL-22, and IFN- γ producing cells, and increasing the frequency of IL-4 producing cells. Therefore, exposure to ethanol can impair the capability of macrophages to exert their effector functions and activate the acquired response related to resistance to P. brasiliensis infection.

Dual Substance Use of Electronic Cigarettes and Alcohol

Electronic cigarettes (ECs) are a modern nicotine delivery system that rapidly grew in widespread use, particularly in younger populations. Given the long history of the comorbidity of alcohol and nicotine use, the rising prevalence of ECs raises the question as to their role in the consumption of alcohol. Of the numerous models of ECs available, JUUL is the most popular. This narrative review aims to determine current trends in literature regarding the relationship between EC and alcohol dual use, as well as hypothesize potential pathogenic tissue damage and summarize areas for future study, including second-hand vapor exposure and calling for standardization among studies. In summary, EC users are more likely to participate in hazardous drinking and are at higher risk for alcohol use disorder (AUD). We surmise the pathogenic damage of dual use may exhibit an additive effect, particularly in pathogen clearance from the lungs, increased inflammation and decreased immune response, physical damage to epithelial cells, and exacerbation of chronic obstructive pulmonary disease (COPD)-like illnesses. A better understanding of pathogenic damages is critical to understand the risks placed on dual users when exposed to respiratory pathogens, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Compounding effect of vitamin D3 diet, supplementation, and alcohol exposure on macrophage response to mycobacterium infection

Vitamin D₃ is known to be a key component in the defense against Mycobacterium tuberculosis (Mtb) infection through the regulation of cytokine and effector molecules. Conversely, alcohol exposure has been recognized as an immune dysregulator. Macrophages were extracted from D₃ deficient and sufficient diet mice and supplemented with D₃ or exposed to ethanol during ex vivo infection using M. bovis BCG, as a surrogate for Mtb. Results of our study indicate that while exogenous supplementation or alcohol exposure did alter immune response, in vivo diet was the greatest determinant of cytokine and effector molecule production. Alcohol exposure was found to profoundly dysregulate primary murine macrophages, with ethanol-exposed cells generally characterized as hyper- or hyporesponsive. Exogenous D₃ supplementation had a normative effect for diet deficient host, however supplementation was not sufficient to compensate for the effects of diet deficiency. Vitamin D₃ sufficient diet resulted in reduced cell cytotoxicity for the majority of time points. Results provide insight into the ramifications of both the individual and combined health risks of D₃ deficiency or alcohol exposure. Given the clinical relevance of D₃ deficiency and alcohol use comorbidities, outcomes of this study have implications in therapeutic approaches for the treatment of tuberculosis disease.

Integrative Physiology of Pneumonia

Pneumonia is a type of acute lower respiratory infection that is common and severe. The outcome of lower respiratory infection is determined by the degrees to which immunity is protective and inflammation is damaging. Intercellular and interorgan signaling networks coordinate these actions to fight infection and protect the tissue. Cells residing in the lung initiate and steer these responses, with additional immunity effectors recruited from the bloodstream. Responses of extrapulmonary tissues, including the liver, bone marrow, and others, are essential to resistance and resilience. Responses in the lung and extrapulmonary organs can also be counterproductive and drive acute and chronic comorbidities after respiratory infection. This review discusses cell-specific and organ-specific roles in the integrated physiological response to acute lung infection, and the mechanisms by which intercellular and interorgan signaling contribute to host defense and healthy respiratory physiology or to acute lung injury, chronic pulmonary disease, and adverse extrapulmonary sequelae. Pneumonia should no longer be perceived as simply an acute infection of the lung. Pneumonia susceptibility reflects ongoing and poorly understood chronic conditions, and pneumonia results in diverse and often persistent deleterious consequences for multiple physiological systems.

Malondialdehyde-Acetaldehyde-Adducted Surfactant Protein Alters Macrophage Functions Through Scavenger Receptor A

BACKGROUND

Reactive aldehydes such as acetaldehyde and malondialdehyde generated as a result of alcohol metabolism and cigarette smoke exposure lead to the formation of malondialdehyde-acetaldehyde-adducted proteins (MAA adducts). These aldehydes can adduct to different proteins such as bovine serum albumin and surfactant protein A or surfactant protein D (SPD). Macrophages play an important role in innate immunity, but the effect of MAA adducts on macrophage function has not yet been examined. Because macrophage scavenger receptor A (SRA; CD204) mediates the uptake of modified proteins, we hypothesized that the effects of MAA-modified proteins on macrophage function are primarily mediated through SRA.

METHODS

We tested this hypothesis by exposing SPD-MAA to macrophages and measuring functions. SPD-MAA treatment significantly stimulated pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α) release in the macrophage cell line, RAW 264.7.

RESULTS

A significant reduction in phagocytosis of zymosan particles was also observed. SPD-MAA stimulated a significant dose-dependent increase in TNF-α and interleukin (IL)-6 release from peritoneal macrophages (PMs) of wild-type (WT) mice. But significantly less TNF-α and IL-6 were released from PMs of SRA-/- mice. We observed a significant reduction in phagocytosis of zymosan particles in PMs from WT mice treated with SPD-MAA. No further SPD-MAA-induced reduction was seen in PMs from SRA-/- mice. SPD-MAA treatment significantly increased SRA mRNA expression, but had no effect on surface receptor protein expression. Protein kinase C alpha inhibitor and NF-κB inhibitor significantly reduced pro-inflammatory cytokine release in response to SPD-MAA.

CONCLUSIONS

In conclusion, our data demonstrate that SRA is important for MAA-adducted protein-mediated effect on macrophage functions.

Alveolar macrophage inflammatory mediator expression is elevated in the setting of alcohol use disorders

Alcohol use disorders (AUDs) are associated with increased susceptibility to pulmonary diseases, including bacterial pneumonia and acute respiratory distress syndrome (ARDS). Alveolar macrophages (AMs) play a vital role in the clearance of pathogens and regulation of inflammation, but these functions may be impaired in the setting of alcohol exposure. We examined the effect of AUDs on profiles of cytokines, chemokines, and growth factors in human AMs isolated from bronchoalveolar lavage (BAL) samples from 19 AUD subjects and 20 age-, sex-, and smoking-matched control subjects. By multiplex bead array, the lysates of AMs from subjects with AUDs had significant elevation in the cytokine tumor necrosis factor α (TNF-α), as well as chemokine (C-X-C motif) ligand 8 (CXCL8), CXCL10, and chemokine (C-C motif) ligand 5 (CCL5) (p < 0.05). Additionally, a 1.8-fold increase in IL-1β, 2.0-fold increase in IL-6, 2.3-fold increase in interferon gamma (IFN-γ), 1.4-fold increase in CCL3, and a 2.3-fold increase in CCL4 was observed in the AUD group as compared to the control group. We also observed compensatory increases in the anti-inflammatory cytokine IL-1RA (p < 0.05). AUD subjects had 5-fold higher levels of CXCL11 mRNA expression (p < 0.05) and a 2.4-fold increase in IL-6 mRNA expression by RT-PCR as well. In these investigations, alcohol use disorders were associated with functional changes in human AMs, suggesting that chronic alcohol exposure portends a chronically pro-inflammatory profile in these cells.

Male adolescent rats display blunted cytokine responses in the CNS after acute ethanol or lipopolysaccharide exposure

Alcohol induces widespread changes in cytokine expression, with recent data from our laboratory having demonstrated that, during acute ethanol intoxication, adult rats exhibit consistent increases in interleukin (IL)-6 mRNA expression in several brain regions, while showing reductions in IL-1 and TNFα expression. Given evidence indicating that adolescence may be an ontogenetic period in which some neuroimmune processes and cells may not yet have fully matured, the purpose of the current experiments was to examine potential age differences in the central cytokine response of adolescent (P31-33days of age) and adult (69-71days of age) rats to either an acute immune (lipopolysaccharide; LPS) or non-immune challenge (ethanol). In Experiment 1, male Sprague-Dawley rats were given an intraperitoneal (i.p.) injection of either sterile saline, LPS (250μg/kg), or ethanol (4-g/kg), and then trunk blood and brain tissue were collected 3h later for measurement of blood ethanol concentrations (BECs), plasma endotoxin, and central mRNA expression of several immune-related gene targets. In Experiment 2, the response to intragastrically (i.g.) administered ethanol was examined and compared to animals given tap water (i.g.). Results showed that LPS stimulated robust increases in expression of IL-1, IL-6, TNFα, and IκBα in the hippocampus, PVN, and amygdala, and that these increases were generally less pronounced in adolescents relative to adults. Following an i.p. ethanol challenge, IL-6 and IκBα expression was significantly increased in both ages in the PVN and amygdala, and adults exhibited even greater increases in IκBα than adolescents. I.g. administration of ethanol also increased IL-6 and IκBα expression in all three brain regions, with hippocampal IL-6 elevated even more so in adults compared to adolescents. Furthermore, assessment of plasma endotoxin concentrations revealed (i) whereas robust increases in plasma endotoxin were observed in adults injected with LPS, no corresponding elevations were seen in adolescents after LPS; and (ii) neither adolescents nor adults demonstrated increases in plasma endotoxin concentrations following i.p. or i.g. ethanol administration. Analysis of BECs indicated that, for both routes of exposure, adolescents exhibited lower BECs than adults. Taken together, these data suggest that categorically different mechanisms are involved in the central cytokine response to antigen exposure versus ethanol administration. Furthermore, these findings confirm once again that acute ethanol intoxication is a potent activator of brain cytokines, and calls for future studies to identify the mechanisms underlying age-related differences in the cytokine response observed during ethanol intoxication.

Zinc insufficiency mediates ethanol-induced alveolar macrophage dysfunction in the pregnant female mouse

AIMS

(a) Establish the minimum number of weeks of chronic ethanol ingestion needed to perturb zinc homeostasis, (b) Examine intracellular zinc status in the alveolar macrophages (AMs) when ethanol ingestion is combined with pregnancy, (c) Investigate whether in vitro zinc treatment reverses the effects of ethanol ingestion on the AM.

METHODS

C57BL/6 female mice were fed a liquid diet (±25% ethanol-derived calories) during preconception and pregnancy. The control group was pair-fed to the ethanol group. In the isolated AMs, we measured intracellular AM zinc levels, zinc transporter expression, alternative activation and phagocytic index. Zinc acetate was added to some cells prior to analysis.

RESULTS

Intracellular zinc levels in the AM decreased within 3 weeks of ethanol ingestion. After ethanol ingestion prior to and during pregnancy, zinc transporter expression and intracellular zinc levels were decreased in the AMs when compared with controls. Bacterial clearance was decreased because the AMs were alternatively activated. In vitro additions of zinc reversed these effects of ethanol.

CONCLUSION

Ethanol ingestion prior to and during pregnancy perturbed AM zinc balance resulting in impaired bacterial clearance, but these effects were ameliorated by in vitro zinc treatments.

Alcoholism: A systemic proinflammatory condition

Excessive ethanol consumption affects virtually any organ, both by indirect and direct mechanisms. Considerable research in the last two decades has widened the knowledge about the paramount importance of proinflammatory cytokines and oxidative damage in the pathogenesis of many of the systemic manifestations of alcoholism. These cytokines derive primarily from activated Kupffer cells exposed to Gram-negative intestinal bacteria, which reach the liver in supra-physiological amounts due to ethanol-mediated increased gut permeability. Reactive oxygen species (ROS) that enhance the inflammatory response are generated both by activation of Kupffer cells and by the direct metabolic effects of ethanol. The effects of this increased cytokine secretion and ROS generation lie far beyond liver damage. In addition to the classic consequences of endotoxemia associated with liver cirrhosis that were described several decades ago, important research in the last ten years has shown that cytokines may also induce damage in remote organs such as brain, bone, muscle, heart, lung, gonads, peripheral nerve, and pancreas. These effects are even seen in alcoholics without significant liver disease. Therefore, alcoholism can be viewed as an inflammatory condition, a concept which opens the possibility of using new therapeutic weapons to treat some of the complications of this devastating and frequent disease. In this review we examine some of the most outstanding consequences of the altered cytokine regulation that occurs in alcoholics in organs other than the liver.

Asymmetric dimethylarginine blocks nitric oxide-mediated alcohol-stimulated cilia beating

The airway epithelium is exposed to alcohol during drinking through direct exhalation of volatized ethanol from the bronchial circulation. Alcohol exposure leads to a rapid increase in the cilia beat frequency (CBF) of bronchial epithelial cells followed by a chronic desensitization of cilia stimulatory responses. This effect is governed in part by the nitric oxide regulation of cyclic guanosine and adenosine monophosphate-dependent protein kinases (PKG and PKA) and is not fully understood. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, is implicated in the pathogenesis of several pulmonary disorders. We hypothesized that the inhibition of nitric oxide synthase by ADMA blocks alcohol-stimulated increases in CBF. To test this hypothesis, ciliated primary bovine bronchial epithelial cells (BBEC) were preincubated with ADMA (100 µM) and stimulated with 100 mM ethanol. CBF was measured and PKA assayed. By 1 hr, ethanol activated PKA, resulting in elevated CBF. Both alcohol-induced PKA activation and CBF were inhibited in the presence of ADMA. ADMA alone had no effect on PKA activity or CBF. Using a mouse model overexpressing the ADMA-degrading enzyme, dimethylarginine dimethylaminohydrolase (DDAH), we examined PKA and CBF in precision-cut mouse lung slices. Alcohol-stimulated increases in lung slice PKA and CBF were temporally enhanced in the DDAH mice versus control mice.

Alcoholism causes alveolar macrophage zinc deficiency and immune dysfunction

RATIONALE

Alcohol use disorders cause oxidative stress in the lower airways and increase susceptibility to pneumonia and lung injury. Currently, no therapeutic options exist to mitigate the pulmonary consequences of alcoholism.

OBJECTIVES

We recently determined in an animal model that alcohol ingestion impairs pulmonary zinc metabolism and causes alveolar macrophage immune dysfunction. The objective of this research is to determine the effects of alcoholism on zinc bioavailability and alveolar macrophage function in human subjects.

METHODS

We recruited otherwise healthy alcoholics (n = 17) and matched control subjects (n = 17) who underwent bronchoscopy for isolation of alveolar macrophages, which were analyzed for intracellular zinc, phagocytic function, and surface expression of granulocyte-macrophage colony-stimulating factor receptor; all three of these indices are decreased in experimental models.

MEASUREMENTS AND MAIN RESULTS

Alcoholic subjects had normal serum zinc, but significantly decreased alveolar macrophage intracellular zinc levels (adjusted means [SE], 718 [41] vs. 948 [25] RFU/cell; P < 0.0001); bacterial phagocytosis (adjusted means [SE], 1,027 [48] vs. 1,509 [76] RFU/cell; P < 0.0001); and expression of granulocyte-macrophage colony-stimulating factor receptor β subunit (adjusted means [SE], 1,471 [42] vs. 2,114 [35] RFU/cell; P < 0.0001]. Treating alveolar macrophages with zinc acetate and glutathione in vitro increased intracellular zinc levels and improved their phagocytic function.

CONCLUSIONS

These novel clinical findings provide evidence that alcohol abuse is associated with significant zinc deficiency and immune dysfunction within the alveolar space and suggest that dietary supplementation with zinc and glutathione precursors could enhance airway innate immunity and decrease the risk for pneumonia or lung injury in these vulnerable individuals.

Alcohol-Mediated Zinc Deficiency Within the Alveolar Space: A Potential Fundamental Mechanism Underlying Oxidative Stress and Cellular Dysfunction in the Alcoholic Lung

Zinc is one of the most abundant trace elements in the human body, and its presence is essential for numerous biological processes including enzymatic activity, immune function, protein synthesis, and wound healing. Given these important roles, zinc has a sophisticated transport system to regulate its homeostasis. Determination of zinc status, however, is difficult to determine as serum levels are closely maintained and are not an accurate reflection of total body zinc or metabolism at the organ level. Fortunately, the discovery of zinc-specific fluorescent dyes has allowed for a much better assessment of zinc status in the respiratory system and has revealed that alcoholism perturbs this highly developed zinc metabolism such that its distribution to the lung and alveolar space is significantly decreased. As a result, this pulmonary zinc deficiency impairs function in the alveolar macrophage, which is the primary host immune cell within the lower airway. Experimental models have demonstrated that correction of this zinc deficiency restores immune function to the alveolar macrophage as best reflected by improved bacterial clearance in response to infection. While the precise mechanisms underlying alcohol-induced zinc deficiency are still under investigation, there is experimental evidence of several important connections with granulocyte–macrophage colony-stimulating factor and oxidative stress, suggesting that alteration of zinc homeostasis may be a fundamental mechanism underlying the cellular pathology seen in the alcohol lung phenotype. This chapter reviews zinc homeostasis and offers insight into our understanding of zinc deficiency in the setting of alcoholism and the potential of zinc as a therapeutic modality in the vulnerable alcoholic host.

Chronic alcohol ingestion increases mortality and organ injury in a murine model of septic peritonitis

Background

Patients admitted to the intensive care unit with alcohol use disorders have increased morbidity and mortality. The purpose of this study was to determine how chronic alcohol ingestion alters the host response to sepsis in mice.

Methods

Mice were randomized to receive either alcohol or water for 12 weeks and then subjected to cecal ligation and puncture. Mice were sacrificed 24 hours post-operatively or followed seven days for survival.

Results

Septic alcohol-fed mice had a significantly higher mortality than septic water-fed mice (74% vs. 41%, p = 0.01). This was associated with worsened gut integrity in alcohol-fed mice with elevated intestinal epithelial apoptosis, decreased crypt proliferation and shortened villus length. Further, alcohol-fed mice had higher intestinal permeability with decreased ZO-1 and occludin protein expression in the intestinal tight junction. The frequency of splenic and bone marrow CD4+ T cells was similar between groups; however, splenic CD4+ T cells in septic alcohol-fed mice had a marked increase in both TNF and IFN-γ production following ex vivo stimulation. Neither the frequency nor function of CD8+ T cells differed between alcohol-fed and water-fed septic mice. NK cells were decreased in both the spleen and bone marrow of alcohol-fed septic mice. Pulmonary myeloperoxidase levels and BAL levels of G-CSF and TFG-β were higher in alcohol-fed mice. Pancreatic metabolomics demonstrated increased acetate, adenosine, xanthine, acetoacetate, 3-hydroxybutyrate and betaine in alcohol-fed mice and decreased cytidine, uracil, fumarate, creatine phosphate, creatine, and choline. Serum and peritoneal cytokines were generally similar between alcohol-fed and water-fed mice, and there were no differences in bacteremia, lung wet to dry weight, or pulmonary, liver or splenic histology.

Conclusions

When subjected to the same septic insult, mice with chronic alcohol ingestion have increased mortality. Alterations in intestinal integrity, the host immune response, and pancreatic metabolomics may help explain this differential response.

Effects of chronic ethanol consumption in experimental sepsis

AIMS

To evaluate the effects of chronic ethanol consumption on the development and the pathophysiology of sepsis, using an experimental model of polymicrobial peritonitis by feces i.p. injection.

METHODS

Forty-day-old male Wistar rats were divided into groups for two experiments: A and B. Experiment A was performed for determination of mortality rates, while experiment B was designed for biochemical analysis and measurement of cytokines before and after sepsis. In both the experiments, treated animals were exposed to a 10% ethanol solution as the single drinking source for 4 weeks, while untreated animals were exposed to tap water over the same period. Food was provided ad libitum. After this period, the animals underwent i.p. fecal injection for induction of sepsis.

RESULTS

Experiment A showed that higher doses of ethanol resulted in early mortality from sepsis that was correlated with the alcohol consumption (high dose = 85.7%, low dose = 14.3%, P = 0.027). In experiment B, cytokine analysis demonstrated important changes resulting from sepsis, which were further affected by ethanol exposure. In addition, glucose and creatinine levels decreased and increased, respectively, after sepsis, but a significant change occurred only in the ethanol group (P < 0.003 glucose, P < 0.01 creatinine). The levels of pro-inflammatory cytokines, interleukin-6 and tumor necrosis factor-α, increased after sepsis, but were less evident after ethanol exposure.

CONCLUSION

These differences may be the result of either early mortality or an increase in the severity of the septic process. Taking into account the high mortality rate and the extreme severity of sepsis after alcohol consumption, often encouraged by advertising, a caution should be given to patients with severe infections and a history of alcohol abuse.

Alcohol abuse, the alveolar macrophage and pneumonia

Alcohol use, and misuse, has been a part of human culture for thousands of years. In the modern medical era, a great deal of attention has been justifiably focused on elucidating the mechanisms underlying the psychological and biological addiction to alcohol. However, a significant percentage, if not the majority, of alcohol-related morbidity and mortality occurs in individuals who do not meet the formal diagnostic criteria for alcohol use disorders. For example, many serious medical consequences of chronic alcohol ingestion can occur in individuals who do not have signs or symptoms of alcohol dependence. There is now clear evidence that even in otherwise healthy-appearing individuals who chronically consume excessive amounts of alcohol, alveolar macrophage immune capacity is impaired and, as a consequence, these individuals are at significantly increased risk of pneumonia. This brief review summarizes some of the key mechanisms underlying this phenomenon and proposes a hypothetical scheme by which alcohol interferes with zinc bioavailability within the alveolar space and thereby dampens macrophage function.

Alcohol abuse and Streptococcus pneumoniae infections: consideration of virulence factors and impaired immune responses

Alcohol is the most frequently abused substance in the world. Both acute and chronic alcohol consumption have diverse and well-documented effects on the human immune system, leading to increased susceptibility to infections like bacterial pneumonia. Streptococcus pneumoniae is the most common bacterial etiology of community-acquired pneumonia worldwide. The frequency and severity of pneumococcal infections in individuals with a history of alcohol abuse is much higher than the general population. Despite this obvious epidemiological relevance, very few experimental studies have focused on the interaction of pneumococci with the immune system of a host acutely or chronically exposed to alcohol. Understanding these host-pathogen interactions is imperative for designing effective prophylactic and therapeutic interventions for such populations. Recent advances in pneumococcal research have greatly improved our understanding of pneumococcal pathogenesis and virulence mechanisms. Additionally, a large body of data is available on the effect of alcohol on the physiology of the lungs and the innate and adaptive immune system of the host. The purpose of this review is to integrate the available knowledge in these diverse areas of for a better understanding of the how the compromised immune system derived from alcohol exposure responds to pneumococcal infections.

Zinc supplementation restores PU.1 and Nrf2 nuclear binding in alveolar macrophages and improves redox balance and bacterial clearance in the lungs of alcohol-fed rats

BACKGROUND

Chronic alcohol abuse causes oxidative stress, impairs alveolar macrophage immune function, and increases the risk of pneumonia and acute lung injury. Recently we determined that chronic alcohol ingestion in rats decreases zinc levels and macrophage function in the alveolar space; provocative findings in that zinc is essential for normal immune and antioxidant defenses. Alveolar macrophage immune function depends on stimulation by granulocyte/monocyte colony-stimulating factor, which signals via the transcription factor PU.1. In parallel, the antioxidant response element signals via the transcription factor Nrf2. However, the role of zinc bioavailability on these signaling pathways within the alveolar space is unknown.

METHODS

To determine the efficacy of dietary zinc supplementation on lung bacterial clearance and oxidative stress, we tested 3 different groups of rats: control-fed, alcohol-fed, and alcohol-fed with zinc supplementation. Rats were then inoculated with intratracheal Klebsiella pneumoniae, and lung bacterial clearance was determined 24 hours later. Isolated alveolar macrophages were isolated from uninfected animals and evaluated for oxidative stress and signaling through PU.1 and Nrf2.

RESULTS

Alcohol-fed rats had a 5-fold decrease in lung bacterial clearance compared to control-fed rats. Dietary zinc supplementation of alcohol-fed rats normalized bacterial clearance and mitigated oxidative stress in the alveolar space, as reflected by the relative balance of the thiol redox pair cysteine and cystine, and increased nuclear binding of both PU.1 and Nrf2 in alveolar macrophages from alcohol-fed rats.

CONCLUSIONS

Dietary zinc supplementation prevents alcohol-induced alveolar macrophage immune dysfunction and oxidative stress in a relevant experimental model, suggesting that such a strategy could decrease the risk of pneumonia and lung injury in individuals with alcohol use disorders.

Alcohol use disorders affect antimicrobial proteins and anti-pneumococcal activity in epithelial lining fluid obtained via bronchoalveolar lavage

AIMS

Our overall objective was to examine whether characteristics of epithelial lining fluid (ELF) from subjects with alcohol use disorders (AUDs) obtained via bronchoalveolar lavage (BAL) contribute to their predisposition to pneumococcal pneumonia. We sought to compare the anti-pneumococcal activity of acellular human BAL from subjects with AUDs to matched controls. Further, differences in BAL lysozyme activity and lactoferrin concentrations between these two groups were examined to determine the effect of AUDs on these antimicrobial proteins.

METHODS

BAL was performed in subjects with AUDs and matched controls. Acellular BAL was used at varying concentrations in an in vitro killing assay of Streptococcus pneumoniae, type 2, and the percent kill of organisms per microgram per milliliter total BAL protein was ascertained. Lysozyme activity and lactoferrin concentrations were measured in BAL from subjects and controls at measured concentrations of BAL protein.

RESULTS

AUD subjects (n = 15) and controls (n = 10) were enrolled in these investigations who were balanced in terms of smoking history. Using a mixed effect model, across the range of BAL protein concentrations, killing of pneumococcus tended to be less potent with BAL fluid from AUD subjects. Additionally, lysozyme activity and lactoferrin concentrations were significantly lower in the AUD group.

CONCLUSIONS

The predisposition for pneumococcal pneumonia among those with AUDs may be in part mediated through effects of alcohol on substances within ELF that include antimicrobial proteins. Clarifying the composition and activity of ELF antimicrobial proteins in the setting of AUDs via investigations with human BAL fluid can help establish their contribution to the susceptibility for pulmonary infections in these individuals.

Ethanol upregulates glucocorticoid-induced leucine zipper expression and modulates cellular inflammatory responses in lung epithelial cells

Alcohol abuse is associated with immunosuppressive and infectious sequelae. Particularly, alcoholics are more susceptible to pulmonary infections. In this report, gene transcriptional profiles of primary human airway epithelial cells exposed to varying doses of alcohol (0, 50, and 100 mM) were obtained. Comparison of gene transcription levels in 0 mM alcohol treatments with those in 50 mM alcohol treatments resulted in 2 genes being upregulated and 16 genes downregulated by at least 2-fold. Moreover, 0 mM and 100 mM alcohol exposure led to the upregulation of 14 genes and downregulation of 157 genes. Among the upregulated genes, glucocorticoid-induced leucine zipper (GILZ) responded to alcohol in a dose-dependent manner. Moreover, GILZ protein levels also correlated with this transcriptional pattern. Lentiviral expression of GILZ small interfering RNA in human airway epithelial cells diminished the alcohol-induced upregulation, confirming that GILZ is indeed an alcohol-responsive gene. Gene silencing of GILZ in A549 cells resulted in secretion of significantly higher amounts of inflammatory cytokines in response to IL-1beta stimulation. The GILZ-silenced cells were more resistant to alcohol-mediated suppression of cytokine secretion. Further data demonstrated that the glucocorticoid receptor is involved in the regulation of GILZ by alcohol. Because GILZ is a key glucocorticoid-responsive factor mediating the anti-inflammatory and immunosuppressive actions of steroids, we propose that similar signaling pathways may play a role in the anti-inflammatory and immunosuppressive effects of alcohol.

Alcohol, signaling, and ECM turnover

Alcohol is recognized as a direct hepatotoxin, but the precise molecular pathways that are important for the initiation and progression of alcohol-induced tissue injury are not completely understood. The current understanding of alcohol toxicity to organs suggests that alcohol initiates injury by generation of oxidative and nonoxidative ethanol metabolites and via translocation of gut-derived endotoxin. These processes lead to cellular injury and stimulation of the inflammatory responses mediated through a variety of molecules. With continuing alcohol abuse, the injury progresses through impairment of tissue regeneration and extracellular matrix (ECM) turnover, leading to fibrogenesis and cirrhosis. Several cell types are involved in this process, the predominant being stellate cells, macrophages, and parenchymal cells. In response to alcohol, growth factors and cytokines activate many signaling cascades that regulate fibrogenesis. This mini-review brings together research focusing on the underlying mechanisms of alcohol-mediated injury in a number of organs. It highlights the various processes and molecules that are likely involved in inflammation, immune modulation, susceptibility to infection, ECM turnover and fibrogenesis in the liver, pancreas, and lung triggered by alcohol abuse.

Acute ethanol exposure attenuates pattern recognition receptor activated macrophage functions

Both clinical and experimental data have linked acute ethanol exposure to increased susceptibility to infection as well as increased morbidity and mortality after injury. Macrophages play an integral role in the innate immune system and are important in priming the adaptive immune system. In this study, we investigated the effect of a single in vivo exposure of macrophages to physiologically relevant levels of ethanol (1.2 and 2.9 g/kg) followed by ex vivo stimulation with lipopolysaccharide (LPS) or bacteria. Our study confirms the work of others showing that a single administration of ethanol suppresses the production of tumor necrosis factor-alpha(TNF-alpha), interleukin-6 (IL-6), and IL-12 in response to LPS. There was no effect of ethanol on LPS induction of cytokine production at 30 min after treatment. In contrast, at 3 h, both doses of ethanol exposure decreased ex vivo TNF-alpha production by splenic and alveolar macrophages. Interestingly, the higher dose of ethanol resulted in sustained suppression of LPS-induced TNF-alpha production at 3 and 6 h after ethanol administration, as well as decreased IL-6 and IL-12 production after 6 h, as compared to control (saline-treated groups). Alveolar macrophages behaved similarly at 3 h after ethanol treatment. LPS-stimulated production of TNF-alpha and IL-6 was reduced at 3 h after ethanol administration, when compared with the saline-treated animals. Alveolar macrophages stimulated for 3 h with bacteria also showed decreased TNF-alpha and IL-6 production after harvested from mice given 2.9 g/kg ethanol for 3 h. This time point and high dose of ethanol also resulted in decreased Pseudomonas aeruginosa phagocytosis by alveolar macrophages. Taken together, we conclude that the effects of physiological levels of ethanol are dose dependent, have effects that last after ethanol is cleared from the circulation, and can affect multiple macrophage functions.

Antigen-presenting cells under the influence of alcohol

The negative influence of alcohol (ethanol) and its metabolites on innate and adaptive immunity is well-recognized. Much attention has recently been focused on the impact of acute and chronic alcohol exposure on antigen-presenting cells (APC). In particular, insights have been gained into how the properties of human blood monocytes and rodent macrophages are influenced by alcohol in vitro and in vivo. Here, we review the impact of alcohol on various aspects of APC function and the underlying mechanisms, including its effects on intracellular signaling events. We also discuss new information regarding the influence of alcohol on various APC populations in the liver, a primary site of alcohol metabolism.

The association between alcohol consumption and risk of COPD exacerbation in a veteran population

BACKGROUND

Alcohol has been associated with COPD-related mortality but has not yet been demonstrated to be an independent risk factor for COPD exacerbation. Our objective was to evaluate the association between alcohol consumption and the subsequent risk of COPD exacerbation.

METHODS

A prospective cohort study of general medicine outpatients seen at one of seven Veterans Affairs (VA) medical centers who returned health screening questionnaires. Three screening questionnaires, AUDIT-C (0 to 12 points), CAGE (0 to 4 points), and a single item about the frequency of drinking six or more drinks on an occasion (binge drinking), were used to classify alcohol consumption. The main outcome, COPD exacerbation, was based on primary VA discharge diagnosis (International Classification of Diseases, Ninth Revision) or outpatient diagnosis of COPD accompanied by prescriptions for either antibiotics or prednisone within 2 days.

RESULTS

Among the 30,503 patients followed up for a median of 3.35 years, those patients with AUDIT-C scores > or = 6, CAGE scores > or = 2, or who reported binge drinking at least weekly were at an increased risk of COPD exacerbation in age-adjusted analysis. Adjusted hazard ratios were 1.4 (95% confidence interval [CI], 1.1 to 1.7) for AUDIT-C score > or = 6, 1.4 (95% CI, 1.3 to 1.5) for CAGE score > or = 2, and 1.6 (95% CI, 1.2 to 2.2) for those who reported binge drinking daily or almost daily. However, with adjustment for measures of tobacco use, the association between alcohol consumption and increased risk of COPD exacerbation was no longer evident.

CONCLUSIONS

Alcohol consumption, whether quantified by AUDIT-C, CAGE score, or binge drinking, was not associated with an increased risk of COPD exacerbation independent of tobacco use.

Dendritic cells in chronic in vivo ethanol exposure models

Dendritic cells (DCs) play a key role in the initiation of effective immune responses against infectious agents because they are unique in their ability to provide antigen-specific activation of naïve T cells. To do this, they must acquire antigen and migrate to spleen or lymph node to present the antigen to T cells in association with costimulatory molecules and cytokines. Murine models of chronic EtOH exposure have been developed for dissecting the mechanisms by which EtOH alters immune cell functions. This chapter details methods for assessing DC functions in such models. Methods are presented for 1) the identification and isolation of various DC subsets from spleen, epidermis, and lung, 2) measurement of LC migration out of epidermis and DC migration into peripheral and peribronchial lymph nodes, and 3) measurement of alloantigen presentation in vitro as well as transgenic T-cell activation in vitro and in vivo.

Acute alcohol intake impairs lung inflammation by changing pro- and anti-inflammatory mediator balance

Previous studies have shown that alcohol (ethanol [EtOH]) intoxication impairs lung immunity by affecting cytokines pivotal to the inflammatory process. The objective of this study was to test the hypothesis that acute alcohol intoxication impairs lung innate immunity by downregulating the expression of proinflammatory mediators while simultaneously upregulating anti-inflammatory mediators. EtOH was administered to the mice 0.5h prior to an intratracheal injection of Escherichia coli lipopolysaccharide (LPS). The animals were killed either 4 or 24h after LPS to recover plasma, lungs, and bronchoalveolar lavage fluid. Lung inflammatory cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1beta), IL-6, macrophage inhibitory factor (MIF), IL-10, TGF-beta, and receptors for TNF-alpha, IL-1beta, IL-6, and TGF-beta as well as glycoprotein (gp)130 and corticosterone (CS) levels were evaluated at mRNA and protein level. While the mRNA expression and the soluble TNF-Rp55 levels were significantly upregulated by EtOH, LPS-induced TNF-alpha activity, TNF-Rp55 mRNA expression, and soluble TNF-Rp55 levels were significantly suppressed. The LPS-induced expression of IL-1beta, IL-6, MIF, gp130, and receptors IL-1RI, IL-1RII, and IL-6Ralpha were also significantly impaired by EtOH. EtOH increased significantly the basal IL-10 activity at 3h, which continued to remain elevated even at 24h. The EtOH effect on IL-10 activity persisted even in LPS-challenged mice. EtOH and LPS augmented lung CS levels independently of each other. EtOH suppressed upregulation of TGF-beta1 mRNA expression by LPS and blocked completely LPS-induced TGF-beta1 secretion. In conclusion, the data suggest that the suppression of acute lung inflammation by EtOH intoxication is largely due to impairment by EtOH of proinflammatory cytokine signaling at the levels of cytokine expression and secretion as well as receptor expression and soluble receptor activity. The augmentation by EtOH of anti-inflammatory mediators' secretion most likely shifts the cytokine balance in the anti-inflammatory direction.

Increased fibronectin expression in lung in the setting of chronic alcohol abuse

RATIONALE

The incidence and severity of the acute respiratory distress syndrome (ARDS) is increased in individuals who abuse alcohol. One possible mechanism by which alcohol increases susceptibility to acute lung injury is through alterations in alveolar macrophage function and induction of tissue remodeling activity. Our objective was to determine whether alcohol abuse, independent of other comorbidities, alters fibronectin and metalloproteinase gene expression in alveolar macrophages and in epithelial lining fluid (ELF) of the lung.

METHODS

Otherwise healthy subjects with alcohol abuse (n=21) and smoking-matched controls (n=17) underwent bronchoalveolar lavage. Alveolar macrophage fibronectin and matrix metalloproteinase (MMP) mRNA expression were measured via reverse transcription-polymerase chain reaction. The supernatant from cultured alveolar macrophages and lung ELF were tested for their ability to induce fibronectin and MMP-9 gene transcription in cell-based assays.

RESULTS

Alveolar macrophages from subjects with alcohol abuse demonstrated increased fibronectin mRNA expression (p<0.001), and their ELF also elicited more fibronectin gene transcription in lung fibroblasts compared with controls (p<0.001). In contrast, alveolar macrophages from subjects with alcohol abuse had decreased MMP-9 and MMP-2 mRNA expression (p<0.03 and p<0.005, respectively). Similarly, the supernatant (p<0.001) and ELF (p<0.01) from these subjects induced less MMP-9 gene transcription in THP-1 cells.

DISCUSSION

Alcohol abuse is associated with increased fibronectin mRNA expression in alveolar macrophages and increased fibronectin-inducing activity in the ELF. This appears to be a specific effect as other tissue remodeling genes, such as MMPs, were not equally affected. These findings suggest activation of tissue remodeling that may contribute to the increased susceptibility for the ARDS observed in alcoholism.

The alcoholic lung: epidemiology, pathophysiology, and potential therapies

Epidemiological evidence gathered only in the past decade reveals that alcohol abuse independently increases the risk of developing the acute respiratory distress syndrome by as much as three- to fourfold. Experimental models and clinical studies are beginning to elucidate the mechanisms underlying this previously unrecognized association and are revealing for the first time that chronic alcohol abuse causes discrete changes, particularly within the alveolar epithelium, that render the lung susceptible to acute edematous injury in response to sepsis, trauma, and other inflammatory insults. Recent studies in relevant animal models as well as in human subjects are identifying common mechanisms by which alcohol abuse targets both the alveolar epithelium and the alveolar macrophage, such that the risks for acute lung injury and pulmonary infections are inextricably linked. Specifically, chronic alcohol ingestion decreases the levels of the antioxidant glutathione within the alveolar space by as much as 80-90%, and, as a consequence, impairs alveolar epithelial surfactant production and barrier integrity, decreases alveolar macrophage function, and renders the lung susceptible to oxidant-mediated injury. These changes are often subclinical and may not manifest as detectable lung impairment until challenged by an acute insult such as sepsis or trauma. However, even otherwise healthy alcoholics have evidence of severe oxidant stress in the alveolar space that correlates with alveolar epithelial and macrophage dysfunction. This review focuses on the epidemiology and the pathophysiology of alcohol-induced lung dysfunction and discusses potential new treatments suggested by recent experimental findings.

Glutathione availability modulates alveolar macrophage function in the chronic ethanol-fed rat

We have previously demonstrated that chronic alcohol exposure decreases glutathione in the alveolar space. Although alcohol use is associated with decreased alveolar macrophage function, the mechanism by which alcohol impairs macrophage phagocytosis is unknown. In the current study, we examined the possibility that ethanol-induced alveolar macrophage dysfunction was secondary to decreased glutathione and subsequent chronic oxidative stress in the alveolar space. After 6 wk of ethanol ingestion, oxidant stress in the alveolar macrophages was evidenced by a 30-mV oxidation of the GSH/GSSG redox potential (P <or= 0.05). For control macrophages, approximately 80% internalized fluorescent Staphylococcus aureus were added in vitro. In contrast, only 20% of the macrophages from the ethanol-fed rats were able to bind and internalize fluorescent S. aureus. This ethanol-induced decreased capacity for phagocytosis was paralleled by increased apoptosis. When added to the ethanol diet, the glutathione precursors procysteine or N-acetyl cysteine normalized glutathione and oxidant stress in the epithelial lining fluid as well as the alveolar macrophages to control values. This attenuation of oxidant stress was associated with normalization of macrophage phagocytosis and viability. These results suggested that decreased glutathione availability in the alcoholic lung contribute to alveolar macrophage dysfunction via oxidative stress, resulting in not only decreased function but decreased viability.

The effects of alcohol on immunity and bacterial infection in the lung

When faced with invading pathogens that can lead to infection, patients must mount an effective and appropriate immune response. Altered immune function in patients who abuse alcohol has long been described in the medical literature. The alcohol-consuming host is particularly prone to infections in the lung, including bacterial pneumonia and tuberculosis. Over the last several decades, there has been increased interest in the immune mechanisms that underlie the increased risk of infection observed in this population. This article will review the basic immunology involved in the host response to an infection and then describe how alcohol disrupts many of these immune mechanisms. It will further provide an overview of lung infections which have been linked to alcohol abuse, and finally, it will address the evolving therapeutic approaches of the immune system that are being advanced to assist in caring for immunosuppressed hosts.

Temporal differences in the ability of ethanol to modulate endotoxin-induced increases in inflammatory cytokines in muscle under in vivo conditions

BACKGROUND

Acute alcohol (EtOH) intoxication may both antagonize and potentiate the ability of monocytes/macrophages to respond to endotoxin (lipopolysaccharide [LPS]). The suppressive effects of EtOH predominate when the duration between EtOH and LPS administration is relatively short, whereas sensitization is observed under conditions when there is a relatively longer delay between EtOH and LPS exposure. Striated muscle is now recognized to possess components of both the afferent and efferent limbs of the innate immune system. The aim of the present study was to determine whether the interval between EtOH and LPS administration differentially affects the mRNA content for selected elements of the innate immune response in skeletal and cardiac muscle and to compare such changes with those occurring in liver and spleen.

METHODS

The content of mRNA for interleukin (IL)-6, IL-1beta, tumor necrosis factor (TNF)-alpha, and high-mobility group box (HMGB)-1, as well as toll-like receptors (TLRs)-2 and -4, were measured in gastrocnemius, heart, liver and spleen from rats orally gavaged with EtOH and then injected with LPS either two or 24 hr thereafter.

RESULTS

EtOH intoxication two hr before LPS acutely suppressed the increased IL-6 mRNA in all tissues and antagonized the increase in plasma and tissue IL-6 protein concentration. Similarly, EtOH blunted the LPS-induced increase in tissue mRNA expression of TNF-alpha and IL-1beta. In contrast, when LPS was given 24 hr after EtOH, the increased IL-6 in striated muscle, but not in liver or spleen, was selectively potentiated. An enhanced LPS responsiveness was also observed for the late-phase cytokine HMGB1 in all tissues; however, the increased tissue expression of TNF-alpha and IL-1beta induced by LPS was not augmented. TLR4 mRNA was decreased in both heart and spleen (but unaltered in skeletal muscle and liver) of rats injected with LPS, and this change was prevented by pretreatment with EtOH. In contrast, EtOH alone increased TLR-2 mRNA content of heart, liver, and spleen but not muscle. LPS also markedly increased TLR2 mRNA in the same three tissues under control conditions, but this increase was attenuated by EtOH administered either two or 24 hr before LPS.

CONCLUSIONS

Under in vivo conditions, the interval between EtOH exposure and LPS differentially affected the synthesis of various cytokines. In this regard, EtOH administered within two hr of LPS generally suppressed IL-6, IL-1beta, and TNF-alpha mRNAs in muscle, heart, liver, and spleen. Delaying the exposure of animals to LPS for 24 hr after EtOH, however, accentuated the increase in IL-6 and HMGB1, and for IL-6, this increased sensitivity appeared localized to striated muscle.

Chronic ethanol ingestion in rats decreases granulocyte-macrophage colony-stimulating factor receptor expression and downstream signaling in the alveolar macrophage

Although it is well recognized that alcohol abuse impairs alveolar macrophage immune function and renders patients susceptible to pneumonia, the mechanisms are incompletely understood. Alveolar macrophage maturation and function requires priming by GM-CSF, which is produced and secreted into the alveolar space by the alveolar epithelium. In this study, we determined that although chronic ethanol ingestion (6 wk) in rats had no effect on GM-CSF expression within the alveolar space, it significantly decreased membrane expression of the GM-CSF receptor in alveolar macrophages. In parallel, ethanol ingestion decreased cellular expression and nuclear binding of PU.1, the master transcription factor that activates GM-CSF-dependent macrophage functions. Furthermore, treatment of ethanol-fed rats in vivo with rGM-CSF via the upper airway restored GM-CSF receptor membrane expression as well as PU.1 protein expression and nuclear binding in alveolar macrophages. Importantly, GM-CSF treatment also restored alveolar macrophage function in ethanol-fed rats, as reflected by endotoxin-stimulated release of TNF-alpha and bacterial phagocytosis. We conclude that ethanol ingestion dampens alveolar macrophage immune function by decreasing GM-CSF receptor expression and downstream PU.1 nuclear binding and that these chronic defects can be reversed relatively quickly with rGM-CSF treatment in vivo.

Drug abuse, innate immunity and hepatitis C virus

Since its discovery in 1989, hepatitis C virus (HCV) has become a major public health problem. HCV chronically infects an estimated 170 million people worldwide. The seroprevalence of anti-HCV antibody in the United States has been estimated at 1.8%, which corresponds to approximately 4 million people. HCV is the most common chronic blood borne infection in the United States, and the leading cause of liver transplantation in developed countries. Injection drug use is the dominant mode of HCV transmission and accounts for up to 90% of current infections. Opiates and other drug abuse, such as alcohol, have been implicated as cofactors in the pathogenesis of HCV disease. Injection drug use has been the most common risk factor identified in alcoholics with HCV infection. Both opiates and alcohol contribute significantly to morbidity and mortality from HCV disease. These drugs most likely act synergistically to promote the development and progression of HCV disease. However, there is limited information available concerning the interaction of the drug abuse with the host cell innate immunity against HCV infection, which is a major barrier to fundamental understanding of the immunopathogenesis of HCV disease. Therefore, defining the role of the drug abuse in the development of chronic HCV infection is of crucial importance and should provide practical guidance toward the reduction of risk factors that interfere with therapeutic approaches for HCV infection and disease. This review paper focuses on the interplay between drug abuse (opiates and alcohol), innate immunity and HCV in the context of the development of HCV disease.

Effects of ethanol on lipids and atherosclerosis

Moderate alcohol consumption is associated with an increase in plasma high density lipoprotein (HDL) cholesterol concentration and a decrease in low density lipoprotein (LDL) cholesterol concentration. Changes in the concentration and composition of lipoproteins are estimated to account for more than half of alcohol's protective effect for coronary heart disease. Alcohol intake also affects plasma proteins involved in lipoprotein metabolism: cholesteryl ester transfer protein, phospholipid transfer protein, lecithin:cholesterol acyltransferase, lipoprotein lipase, hepatic lipase, and phospholipases. In addition, alcohol intake may result in acetaldehyde modification of apolipoproteins. Furthermore, "abnormal" lipids, phosphatidylethanol and fatty acid ethyl esters are formed in the presence of ethanol and are associated with lipoproteins in plasma. Ethanol and ethanol-induced modifications of lipids may modulate the effects of lipoproteins on the cells in the arterial wall. The molecular mechanisms involved in these processes are complex, requiring further study to better understand the specific effects of ethanol in the pathogenesis of atherosclerosis. This review discusses the effects of ethanol on lipoproteins and lipoprotein metabolism, as well as the novel effects of lipoproteins on vascular wall cells.

Interaction Between Alcohol and Exercise

Alcohol use, particularly excessive alcohol consumption is one of the most serious health risks in the world. A relationship between sport, exercise and alcohol consumption is clear and long-standing. Alcohol continues to be the most frequently consumed drug among athletes and habitual exercisers and alcohol-related problems appear to be more common in these individuals. Alcohol use is directly linked to the rate of injury sustained in sport events and appears to evoke detrimental effects on exercise performance capacity. The model of alcohol consumption in human experimental studies has either been acute (single dose) or chronic (repeated doses over a period). These studies suggested that alcohol consumption decreases the use of glucose and amino acids by skeletal muscles, adversely affects energy supply and impairs the metabolic process during exercise. In addition, chronic alcohol use is associated with increased citrate synthase activity and decreased cross-sectional area of type I, IIa and IIb fibres. There is evidence to suggest that exercise may attenuate the ethanol-induced decline in hepatic mitochondria and accelerates ethanol metabolism by the liver. Exercise training seems to reduce the extent of the oxidative damage caused by ethanol. Evidence generated from in vitro experiments and animal studies have also suggested that ethanol administration decreased skeletal muscle capillarity and increased pyruvate kinase and lactate dehydrogenase activities. Substantial epidemiological evidence has been accrued showing that moderate ingestion of alcohol may reduce the incidence of cardiovascular diseases. Although the existing evidence is often confusing and disparate, one of the mechanisms by which alcohol may reduce the incidence of mortality of cardiovascular diseases is through raising levels of high-density lipoprotein cholesterol. Available evidence suggests that exercise and moderate alcohol consumption may have favourable effects on blood coagulation and fibrinolysis; however, compelling experimental evidence is lacking to endorse this notion. Occasional and chronic alcohol consumption is usually linked with unfavourable alterations in platelet aggregation and function and may be associated with platelet-related thrombus formation. Although the effects of alcohol consumption on the rheological properties of the blood are not known, recent experimental evidence suggests that alcohol use following exercise is associated with unfavourable changes in the main determinants of blood viscosity. It is well documented that alcohol use modulates the immune system and impairs host defence. Compelling evidence is also mounting to suggest that chronic alcohol use is linked with adverse effects on the body systems and organs including the brain, the cardiovascular system and the liver.

Altered immune parameters in chronic alcoholic patients at the onset of infection and of septic shock

INTRODUCTION

Chronic alcoholic patients have a threefold to fourfold increased risk for developing a severe infection or septic shock after surgery, which might be due to altered immune response. The aim of this outcome matched study was to investigate proinflammatory and anti-inflammatory immune parameters during the course of infection and subsequent septic shock in chronic alcoholic patients, and to compare these parameters with those in nonalcoholic patients.

METHODS

Twenty-eight patients from a cohort of fifty-six with either pneumonia or peritonitis and subsequent septic shock were selected. Fourteen patients were chronic alcoholics whereas fourteen were nonalcoholic patients. Chronic alcoholic patients met criteria (Diagnostic and Statistical Manual of Mental Disorders IV, of the American Psychiatric Association) for alcohol abuse or dependence. Measurements were performed during the onset of infection (within 24 hours after the onset of infection), in early septic shock (within 12 hours after onset of septic shock) and in late septic shock (72 hours after the onset). Blood measurements included proinflammatory and anti-inflammatory cytokines.

RESULTS

Chronic alcoholic patients exhibited significantly lower plasma levels of IL-8 (P < 0.010) during the onset of infection than did matched nonalcoholic patients. In early septic shock, chronic alcoholic patients had significantly decreased levels of IL-1beta (P < 0.015), IL-6 (P < 0.016) and IL-8 (P < 0.010). The anti-inflammatory parameters IL-10 and tumour necrosis factor receptors I and II did not differ between alcoholic and nonalcoholic patients.

CONCLUSION

At the onset of infection and during early septic shock, chronic alcoholic patients had lower levels of proinflammatory immune parameters than did nonalcoholic patients. Therefore, immunomodulatory therapy administered early may be considered in chronic alcoholic patients at the onset of an infection because of their altered proinflammatory immune response.

Alcohol potentiates HIV-1 infection of human blood mononuclear phagocytes

BACKGROUND

Acute and chronic alcohol abuse impairs various functions of the immune system and thus has been implicated as a cofactor in HIV infection. The mechanisms by which alcohol affects the function of human immune cells that are the targets for HIV are unknown.

METHODS

Human blood monocyte-derived macrophages (MDM) were incubated with or without alcohol (10-40 mM) for 24 hr and then infected with HIV for 24 hr. Culture supernatants were harvested for HIV reverse transcription assay. HIV entry receptor (CCR5, CD4, and CXCR4) expression was determined by reverse transcription-polymerase chain reaction and flow cytometry assays. Beta-chemokines were analyzed using enzyme-linked immunosorbent assay. Different HIV strains (Bal, SF-162, 89.6, and UG024) were used for infection experiments. In addition, ADA (macrophage-tropic strain) and murine leukemia virus envelope-pseudotyped HIV infection was carried out.

RESULTS

Although alcohol had little effect on HIV T-lymphocyte-tropic strain infection, it significantly enhanced HIV R5 strain infection in MDM. The enhancing effect of alcohol on the HIV R5 strain was further evidenced by the observation that the R5 (ADA) strain envelope-pseudotyped HIV infection is markedly increased by alcohol, whereas murine leukemia virus envelope-pseudotyped HIV infection was not affected. Alcohol significantly up-regulated CCR5 receptor expression and inhibited the endogenous production of beta-chemokines by MDM.

CONCLUSION

Alcohol, through the down-regulation of beta-chemokine production and the up-regulation of CCR5 receptor expression, enhances HIV R5 strain infection of MDM and may have an important role as a cofactor in the progression of HIV disease.

Effect of alcohol on lipids and lipoproteins in relation to atherosclerosis

Several studies indicate that light-to-moderate alcohol consumption is associated with a low prevalence of coronary heart disease. An increase in high-density lipoprotein (HDL) cholesterol is associated with alcohol intake and appears to account for approximately half of alcohol's cardioprotective effect. In addition to changes in the concentration and composition of lipoproteins, alcohol consumption may alter the activities of plasma proteins and enzymes involved in lipoprotein metabolism: cholesteryl ester transfer protein, phospholipid transfer protein, lecithin:cholesterol acyltransferase, lipoprotein lipase, hepatic lipase, paraoxonase-1 and phospholipases. Alcohol intake also results in modifications of lipoprotein particles: low sialic acid content in apolipoprotein components of lipoprotein particles (e.g., HDL apo E and apo J) and acetaldehyde modification of apolipoproteins. In addition, "abnormal" lipids, phosphatidylethanol, and fatty acid ethyl esters formed in the presence of ethanol are associated with lipoproteins in plasma. The effects of lipoproteins on the vascular wall cells (endothelial cells, smooth muscle cells, and monocyte/macrophages) may be modulated by ethanol and the alterations further enhanced by modified lipids. The present review discusses the effects of alcohol on lipoproteins in cholesterol transport, as well as the novel effects of lipoproteins on vascular wall cells.

Ethanol metabolism is not required for inhibition of LPS-stimulated transcription of inducible nitric oxide synthase

We examined the effect of inhibition of ethanol metabolism on ethanol-mediated suppression of Escherichia coli endotoxin (LPS-induced upregulation of transcription and release of inducible nitric oxide synthase (iNOS) and tumor necrosis factor alpha (TNFalpha) from rat alveolar macrophages (AM) in vivo. Ethanol (3.45 and 5.5 g/kg/IP) and t-butanol (3.7 g/kg, IP), given 30 min before intratracheal administration of LPS (1.0 mg/kg), inhibited the upregulation of iNOS mRNA and protein, determined by competitor equalized RT-PCR and Western immunoblot, respectively, but not TNFalpha mRNA in AM obtained 2 h after LPS administration by bronchoalveolar lavage (BAL). However, ethanol and t-butanol inhibited LPS-stimulated nitrate and nitrite (RNI) and TNFalpha protein in BAL fluid. Pretreatment of rats with 4-methylpyrazole (100 mg/kg, IP) 2 h before, or disulfiram 30 min before, administration of ethanol (3.45 g/kg, IP) failed to attenuate the inhibitory effect on iNOS mRNA or protein. t-Butyl hydroperoxide (100 mg/kg, IP) given to rats 30 min before administration of LPS enhanced LPS-mediated upregulation of iNOS mRNA and TNFalpha protein in AM and BAL fluid. The inhibitory effect of ethanol on iNOS mRNA was not mediated by an interaction with elevated levels of circulating corticosterone because pretreatment of rats with RU-38486 (100 mg/kg, IM), which inhibited prednisolone (50 mg/kg, IM), induced suppression of LPS-stimulated iNOS mRNA, and failed to attenuate ethanol-mediated inhibition of LPS-stimulated iNOS mRNA in AM. We conclude that metabolism of ethanol to acetaldehyde via alcohol dehydrogenase is not required for ethanol-mediated suppression of LPS-induced iNOS transcription and TNFalpha synthesis/release in AM. Moreover, an interaction of ethanol or acetaldehyde with circulating corticosterone is not involved in ethanol-mediated attenuation of LPS-stimulated iNOS mRNA or protein or TNFalpha protein in the lung. Speculatively, because oxidation of t-butanol to t-butylhydroperoxide results in activation, rather than inhibition, of iNOS and TNF-alpha, the reported ethanol-mediated enhancement of iNOS mRNA may result from the action of the hydroxyethyl radical.

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.

Binding of fatty acid ethyl esters to albumin for transport to cells in culture

Fatty acid ethyl esters (FAEE) are non-oxidative products of ethanol metabolism that have been proposed to mediate pathological changes in various organs and tissues resulting from excessive ethanol consumption. Evidence supporting this proposal is scant, however, mainly because of the lack of adequate methods with which to solubilize the highly hydrophobic FAEE in aqueous medium for testing under physiological conditions. In this report we describe a simple and practical method for solubilizing FAEE in aqueous medium by binding them to albumin. We also report that the albumin-bound FAEE are readily taken up by rat alveolar macrophages in culture. The availability of FAEE bound to albumin, their main physiological carrier in vivo, will facilitate the investigation of the role that these metabolites may have in mediating pathological changes associated with excess ethanol consumption.

Alcohol intoxication and withdrawal: the role of nitric oxide

Nitric oxide is an important messenger in the central nervous system and several types of evidence suggest that it mediates various alcohol effects. Treatment with a nitric oxide synthase inhibitor enhances the acute central depressant or anesthetic effect of alcohol and decreases some stimulatory effects of alcohol withdrawal after chronic alcohol treatment. Conversely, treatment with a nitric oxide donor inhibits the anesthetic effect of alcohol, blocks the effect of the nitric oxide synthase inhibitor on alcohol anesthesia, and enhances the severity of some alcohol withdrawal signs. These results indicate that changes in nitric oxide synthesis mediate some aspects of alcohol intoxication and withdrawal and that nitric oxide systems represent an important therapeutic target for the development of agents to treat alcoholism and alcohol intoxication.

Tumor necrosis factor-alpha internalization and degradation by isolated hepatocytes of rats exposed to ethanol

Internalization and degradation of human recombinant [125I]TNF-alpha was studied in hepatocytes isolated from rats exposed to ethanol (EtOH) either acutely (i.p. injection, 2.2 g kg(-1) b.wt.) or chronically (14-16 weeks of EtOH feeding in liquid diet). Both acute and chronic EtOH exposure diminished cytokine binding to the cell-surface receptors. In the acute group, EtOH increased internalization of the cytokine, accelerated its disappearance from the cell surface, and markedly reduced its conversion into acid-soluble 125I-containing compounds. In the chronic group, EtOH did not markedly affect these parameters. Internalization and degradation of the cytokine in the chronic group was much lower than in the acute group. It is concluded that EtOH interferes not only with the cytokine binding to the cell-surface receptors, as demonstrated in previous studies, but also with postbinding events, such as internalization and intracellular degradation of TNF-alpha. Possible mechanisms of action of EtOH are discussed.

Alveolar macrophage release of tumor necrosis factor-alpha in chronic alcoholics without liver disease

Alcohol is an immunosuppressive drug, and chronic abuse has been associated with increased susceptibility to a variety of infections, including bacterial pneumonia and tuberculosis. Alveolar macrophages are the resident phagocytes of the lung and play a central role in lung host defenses against infection ranging from direct antibacterial activity to the release of proinflammatory cytokines such as tumor necrosis factor-alpha (TNFalpha). TNFalpha, in particular, plays a key role in the development of the early inflammatory response. In this study, we investigated the effects of chronic alcohol consumption on alveolar macrophage release of TNFalpha in vitro. We prospectively studied lipopolysaccharide (LPS)-stimulated release of TNFalpha from alveolar macrophages obtained from bronchoalveolar lavage fluid (BALF) in 22 alcoholic (18 smokers, 4 nonsmokers) and 7 nondrinking healthy volunteers (3 smokers, 4 nonsmokers). The total number of cells recovered by bronchoalveolar lavage (BAL) and their differential distribution were not significantly different in alcoholics versus controls (43 +/- 8 x 10(6) and 39 +/- 13 x 10(6), respectively). However, the total number of cells recovered from BALF was significantly higher in smokers (51 +/- 8 x 10(6)) than in nonsmokers (19 +/- 5 x 10(6)). Spontaneous (basal) release of TNFalpha by alveolar macrophages was the same in alcoholics and controls. In contrast, LPS-stimulated release of TNFalpha was significantly suppressed in alcoholics compared with that of controls (1343 +/- 271 vs. 3806 +/- 926 U TNF/ml/10(6) cells, respectively, p < 0.015). When controlled for smoking, LPS-stimulated TNFalpha production was suppressed in alcoholic nonsmokers (563 +/- 413 U TNF/ml/10(6)) compared with control nonsmokers (5113 +/- 1264 U TNF/ml/10(6)). LPS-stimulated TNFalpha production was also less in control smokers (2063 +/- 386 U TNF/ml/10(6) cells) than in control nonsmokers (5113 +/- 1264 U TNF/ml/10(6) cells). There was no difference in TNFalpha production between smoking alcoholics and smoking control subjects. We conclude that chronic alcohol consumption significantly suppresses LPS-stimulated alveolar macrophage production of TNFalpha. This effect is obscured if the subject also smokes. Because TNFalpha production is an important element in host defense, this may explain, in part, the susceptibility of chronic alcohol abusers to a variety of infections.