Acute alcohol intoxication suppresses the pulmonary ELR-negative CXC chemokine response to lipopolysaccharide

Storage with ethanol attenuates the red blood cell storage lesion

BACKGROUND

Current management of hemorrhagic shock relies on control of surgical bleeding along with resuscitation with packed red blood cells and plasma in a 1-to-1 ratio. Transfusion, however, is not without consequence as red blood cells develop a series of biochemical and physical changes during storage termed "the red blood cell storage lesion." Previous data has suggested that ethanol may stabilize the red blood cell membrane, resulting in improved deformability. We hypothesized that storage of packed red blood cells with ethanol would alter the red blood cell storage lesion.

METHODS

Mice underwent donation and storage of red blood cells with standard storage conditions in AS-3 alone or ethanol at concentrations of 0.07%, 0.14%, and 0.28%. The red blood cell storage lesion parameters of microvesicles, Band-3, free hemoglobin, annexin V, and erythrocyte osmotic fragility were measured and compared. In additional experiments, the mice underwent hemorrhage and resuscitation with stored packed red blood cells to further evaluate the in vivo inflammatory impact.

RESULTS

Red blood cells stored with ethanol demonstrated decreased microvesicle accumulation and Band-3 levels. There were no differences in phosphatidylserine or cell-free hemoglobin levels. After hemorrhage and resuscitation with packed red blood cells stored with 0.07% ethanol, mice demonstrated decreased serum levels of interleukin-6, macrophage inflammatory protein-1α, keratinocyte chemokine, and tumor necrosis factor α compared to those mice receiving packed red blood cells stored with additive solution-3.

CONCLUSION

Storage of murine red blood cells with low-dose ethanol results in decreased red blood cell storage lesion severity. Resuscitation with packed red blood cells stored with 0.07% ethanol also resulted in a decreased systemic inflammatory response in a murine model of hemorrhage.

Cellular Bioenergetics: Experimental Evidence for Alcohol-induced Adaptations

At-risk alcohol use is associated with multisystemic effects and end-organ injury, and significantly contributes to global health burden. Several alcohol-mediated mechanisms have been identified, with bioenergetic maladaptation gaining credence as an underlying pathophysiological mechanism contributing to cellular injury. This evidence-based review focuses on the current knowledge of alcohol-induced bioenergetic adaptations in metabolically active tissues: liver, cardiac and skeletal muscle, pancreas, and brain. Alcohol metabolism itself significantly interferes with bioenergetic pathways in tissues, particularly the liver. Alcohol decreases states of respiration in the electron transport chain, and activity and expression of respiratory complexes, with a net effect to decrease ATP content. In addition, alcohol dysregulates major metabolic pathways, including glycolysis, the tricarboxylic acid cycle, and fatty acid oxidation. These bioenergetic alterations are influenced by alcohol-mediated changes in mitochondrial morphology, biogenesis, and dynamics. The review highlights similarities and differences in bioenergetic adaptations according to tissue type, pattern of (acute vs. chronic) alcohol use, and energy substrate availability. The compromised bioenergetics synergizes with other critical pathophysiological mechanisms, including increased oxidative stress and accelerates cellular dysfunction, promoting senescence, programmed cell death, and end-organ injury.

Ethanol Intoxication Impairs Respiratory Function and Bacterial Clearance and Is Associated With Neutrophil Accumulation in the Lung After Streptococcus pneumoniae Infection

Alcohol consumption is commonplace in the United States and its prevalence has increased in recent years. Excessive alcohol use is linked to an increased risk of infections including pneumococcal pneumonia, mostly commonly caused by Streptococcus pneumoniae. In addition, pneumonia patients with prior alcohol use often require more intensive treatment and longer hospital stays due to complications of infection. The initial respiratory tract immune response to S. pneumoniae includes the production of pro-inflammatory cytokines and chemokines by resident cells in the upper and lower airways which activate and recruit leukocytes to the site of infection. However, this inflammation must be tightly regulated to avoid accumulation of toxic by-products and subsequent tissue damage. A majority of previous work on alcohol and pneumonia involve animal models utilizing high concentrations of ethanol or chronic exposure and offer conflicting results about how ethanol alters immunity to pathogens. Further, animal models often employ a high bacterial inoculum which may overwhelm the immune system and obscure results, limiting their applicability to the course of human infection. Here, we sought to determine how a more moderate ethanol exposure paradigm affects respiratory function and innate immunity in mice after intranasal infection with 10⁴ colony forming units of S. pneumoniae. Ethanol-exposed mice displayed respiratory dysfunction and impaired bacterial clearance after infection compared to their vehicle-exposed counterparts. This altered response was associated with increased gene expression of neutrophil chemokines Cxcl1 and Cxcl2 in whole lung homogenates, elevated concentrations of circulating granulocyte-colony stimulating factor (G-CSF), and higher neutrophil numbers in the lung 24 hours after infection. Taken together, these findings suggest that even a more moderate ethanol consumption pattern can dramatically modulate the innate immune response to S. pneumoniae after only 3 days of ethanol exposure and provide insight into possible mechanisms related to the compromised respiratory immunity seen in alcohol consumers with pneumonia.

Malondialdehyde-Acetaldehyde Adduct Formation Decreases Immunoglobulin A Transport across Airway Epithelium in Smokers Who Abuse Alcohol

Alcohol misuse and smoking are risk factors for pneumonia, yet the impact of combined cigarette smoke and alcohol on pneumonia remains understudied. Smokers who misuse alcohol form lung malondialdehyde-acetaldehyde (MAA) protein adducts and have decreased levels of anti-MAA secretory IgA (sIgA). Transforming growth factor-β (TGF-β) down-regulates polymeric Ig receptor (pIgR) on mucosal epithelium, resulting in decreased sIgA transcytosis to the mucosa. It is hypothesized that MAA-adducted lung protein increases TGF-β, preventing expression of epithelial cell pIgR and decreasing sIgA. Cigarette smoke and alcohol co-exposure on sIgA and TGF-β in human bronchoalveolar lavage fluid and in mice instilled with MAA-adducted surfactant protein D (SPD-MAA) were studied herein. Human bronchial epithelial cells (HBECs) and mouse tracheal epithelial cells were treated with SPD-MAA and sIgA and TGF-β was measured. Decreased sIgA and increased TGF-β were observed in bronchoalveolar lavage from combined alcohol and smoking groups in humans and mice. CD204 (MAA receptor) knockout mice showed no changes in sIgA. SPD-MAA decreased pIgR in HBECs. Conversely, SPD-MAA stimulated TGF-β release in both HBECs and mouse tracheal epithelial cells, but not in CD204 knockout mice. SPD-MAA stimulated TGF-β in alveolar macrophage cells. These data show that MAA-adducted surfactant protein stimulates lung epithelial cell TGF-β, down-regulates pIgR, and decreases sIgA transcytosis. These data provide a mechanism for the decreased levels of sIgA observed in smokers who misuse alcohol.

Acute Ethanol Exposure Promotes Autophagy-Lysosome Pathway-Dependent ASIC1a Protein Degradation and Protects Against Acidosis-Induced Neurotoxicity

Tissue acidosis is a common feature of brain ischemia which causes neuronal injury. Activation of acid-sensing ion channel 1a (ASIC1a) plays an important role in acidosis-mediated neurotoxicity. Acute ethanol administration has been shown to provide neuroprotective effects during ischemic stroke, but the precise mechanisms have yet to be determined. In this study, we investigated the effect of ethanol on the activity/expression of ASIC1a channels and acidosis-induced neurotoxicity. We showed that acute treatment of neuronal cells with ethanol for more than 3 h could reduce ASIC1a protein expression, ASIC currents, and acid-induced [Ca²⁺]_i elevation. We further demonstrated that ethanol-induced reduction of ASIC1a expression is mediated by autophagy-lysosome pathway (ALP)-dependent protein degradation. Finally, we showed that ethanol protected neuronal cells against acidosis-induced cytotoxicity, which effect was mimicked by autophagy activator rapamycin and abolished by autophagy inhibitor CQ. Together, these results indicate that moderate acute ethanol exposure can promote autophagy-lysosome pathway-dependent ASIC1a protein degradation and protect against acidosis-induced neurotoxicity.

Human Binge Alcohol Intake Inhibits TLR4-MyD88 and TLR4-TRIF Responses but Not the TLR3-TRIF Pathway: HspA1A and PP1 Play Selective Regulatory Roles

Binge/moderate alcohol suppresses TLR4-MyD88 proinflammatory cytokines; however, alcohol's effects on TLR-TRIF signaling, especially after in vivo exposure in humans, are unclear. We performed a comparative analysis of the TLR4-MyD88, TLR4-TRIF, and TLR3-TRIF pathways in human monocytes following binge alcohol exposure. Mechanistic regulation of TLR-TRIF signaling by binge alcohol was evaluated by analyzing IRF3 and TBK1, upstream regulator protein phosphatase 1 (PP1), and immunoregulatory stress proteins HspA1A and XBP-1 in alcohol-treated human and mouse monocytes/macrophages. Two approaches for alcohol exposure were used: in vivo exposure of primary monocytes in binge alcohol-consuming human volunteers or in vitro exposure of human monocytes/murine macrophages to physiological alcohol concentrations (25-50 mM ethanol), followed by LPS (TLR4) or polyinosinic-polycytidylic acid (TLR3) stimulation ex vivo. In vivo and in vitro binge alcohol exposure significantly inhibited the TLR4-MyD88 cytokines TNF-α and IL-6, as well as the TLR4-TRIF cytokines/chemokines IFN-β, IP-10, and RANTES, in human monocytes, but not TLR3-TRIF-induced cytokines/chemokines, as detected by quantitative PCR and ELISA. Mechanistic analyses revealed TBK-1-independent inhibition of the TLR4-TRIF effector IRF3 in alcohol-treated macrophages. Although stress protein XBP-1, which is known to regulate IRF3-mediated IFN-β induction, was not affected by alcohol, HspA1A was induced by in vivo alcohol in human monocytes. Alcohol-induced HspA1A was required for inhibition of TLR4-MyD88 signaling but not TLR4-TRIF cytokines in macrophages. In contrast, inhibition of PP1 prevented alcohol-mediated TLR4-TRIF tolerance in macrophages. Collectively, our results demonstrate that in vivo and in vitro binge alcohol exposure in humans suppresses TLR4-MyD88 and TLR4-TRIF, but not TLR3-TRIF, responses. Whereas alcohol-mediated effects on the PP1-IRF3 axis inhibit the TLR4-TRIF pathway, HspA1A selectively suppresses the TLR4-MyD88 pathway in monocytes/macrophages.

Binge alcohol consumption 18 h after induction of sepsis in a mouse model causes rapid overgrowth of bacteria, a cytokine storm, and decreased survival

Alcohol abuse increases vulnerability to infections and infection-related mortality. In previous studies, we found that acute alcohol abuse in a binge-drinking model in mice decreased resistance to bacterial sepsis when alcohol was administered near the time of bacterial challenge. In the present study, we investigated the effects of alcohol administered later in the course of sepsis (18 h after injection of Escherichia coli). Our working hypothesis was that decreased production of cytokines caused by alcohol at this time would actually improve survival, because overproduction of pro-inflammatory mediators is thought to be the proximate cause of mortality in sepsis. Unexpectedly, administration of alcohol late in the course of sepsis led to a rapid increase in the number of viable bacteria in the peritoneal cavity. Significant increases in the concentrations of several cytokines and chemokines coincided with the increased number of bacteria in alcohol-treated mice and decreased survival time. These results demonstrated our working hypothesis to be incorrect, and reiterated the complexity of sepsis. Hypothermia is a consistent feature in this model of sepsis. In control mice (E. coli only), body temperature was near normal by 18 h or 21 h after administration of E. coli, but in mice treated with alcohol 18 h after E. coli, hypothermia was significant 3 h later and ultimately mortality was significantly increased. However, counteracting the hypothermic effect of alcohol by external warming of mice led to earlier mortality, demonstrating that hypothermia was not the major cause of mortality. These results, along with previous results from studies in which alcohol was given before initiation of sepsis, suggest that decreased cytokine and chemokine production may not be the key effect of alcohol that decreases resistance to sepsis. It seems more likely that suppression of mechanisms by which macrophages and neutrophils kill bacteria is critical, and this can occur even in the presence of high levels of cytokines and chemokines.

Alcohol and lung injury and immunity

Annually, excessive alcohol use accounts for more than $220 billion in economic costs and 80,000 deaths, making excessive alcohol use the third leading lifestyle-related cause of death in the US. Patients with an alcohol-use disorder (AUD) also have an increased susceptibility to respiratory pathogens and lung injury, including a 2-4-fold increased risk of acute respiratory distress syndrome (ARDS). This review investigates some of the potential mechanisms by which alcohol causes lung injury and impairs lung immunity. In intoxicated individuals with burn injuries, activation of the gut-liver axis drives pulmonary inflammation, thereby negatively impacting morbidity and mortality. In the lung, the upper airway is the first checkpoint to fail in microbe clearance during alcohol-induced lung immune dysfunction. Brief and prolonged alcohol exposure drive different post-translational modifications of novel proteins that control cilia function. Proteomic approaches are needed to identify novel alcohol targets and post-translational modifications in airway cilia that are involved in alcohol-dependent signal transduction pathways. When the upper airway fails to clear inhaled pathogens, they enter the alveolar space where they are primarily cleared by alveolar macrophages (AM). With chronic alcohol ingestion, oxidative stress pathways in the AMs are stimulated, thereby impairing AM immune capacity and pathogen clearance. The epidemiology of pneumococcal pneumonia and AUDs is well established, as both increased predisposition and illness severity have been reported. AUD subjects have increased susceptibility to pneumococcal pneumonia infections, which may be due to the pro-inflammatory response of AMs, leading to increased oxidative stress.

Gene expression profile analysis of rat cerebellum under acute alcohol intoxication

Acute alcohol intoxication, a common disease causing damage to the central nervous system (CNS) has been primarily studied on the aspects of alcohol addiction and chronic alcohol exposure. The understanding of gene expression change in the CNS during acute alcohol intoxication is still lacking. We established a model for acute alcohol intoxication in SD rats by oral gavage. A rat cDNA microarray was used to profile mRNA expression in the cerebella of alcohol-intoxicated rats (experimental group) and saline-treated rats (control group). A total of 251 differentially expressed genes were identified in response to acute alcohol intoxication, in which 208 of them were up-regulated and 43 were down-regulated. Gene ontology (GO) term enrichment analysis and pathway analysis revealed that the genes involved in the biological processes of immune response and endothelial integrity are among the most severely affected in response to acute alcohol intoxication. We discovered five transcription factors whose consensus binding motifs are overrepresented in the promoter region of differentially expressed genes. Additionally, we identified 20 highly connected hub genes by co-expression analysis, and validated the differential expression of these genes by real-time quantitative PCR. By determining novel biological pathways and transcription factors that have functional implication to acute alcohol intoxication, our study substantially contributes to the understanding of the molecular mechanism underlying the pathology of acute alcoholism.

Response of Differentiated Human Airway Epithelia to Alcohol Exposure and Klebsiella Pneumoniae Challenge

Alcohol abuse has been associated with increased susceptibility to pulmonary infection. It is not fully defined how alcohol contributes to the host defense compromise. Here primary human airway epithelial cells were cultured at an air-liquid interface to form a differentiated and polarized epithelium. This unique culture model allowed us to closely mimic lung infection in the context of alcohol abuse by basolateral alcohol exposure and apical live bacterial challenge. Application of clinically relevant concentrations of alcohol for 24 hours did not significantly alter epithelial integrity or barrier function. When apically challenged with viable Klebsiella pneumoniae, the cultured epithelia had an enhanced tightness which was unaffected by alcohol. Further, alcohol enhanced apical bacterial growth, but not bacterial binding to the cells. The cultured epithelium in the absence of any treatment or stimulation had a base-level IL-6 and IL-8 secretion. Apical bacterial challenge significantly elevated the basolateral secretion of inflammatory cytokines including IL-2, IL-4, IL-6, IL-8, IFN-γ, GM-CSF, and TNF-α. However, alcohol suppressed the observed cytokine burst in response to infection. Addition of adenosine receptor agonists negated the suppression of IL-6 and TNF-α. Thus, acute alcohol alters the epithelial cytokine response to infection, which can be partially mitigated by adenosine receptor agonists.

Role of acute ethanol exposure and TLR4 in early events of sepsis in a mouse model

Sepsis is a major cause of death worldwide. The associated risks and mortality are known to significantly increase on exposure to alcohol (chronic or acute). The underlying mechanisms of the association of acute ethanol ingestion and poor prognosis of sepsis are largely unknown. The study described here was designed to determine in detail the role of ethanol and TLR4 in the pathogenesis of the sepsis syndrome. The effects of acute ethanol exposure and TLR4 on bacterial clearance, spleen cell numbers, peritoneal macrophage numbers, and cytokine production were evaluated using wild-type and TLR4 hyporesponsive mice treated with ethanol and then challenged with a nonpathogenic strain of Escherichia coli. Ethanol-treated mice exhibited a decreased clearance of bacteria and produced lesser amounts of most pro-inflammatory cytokines in both strains of mice at 2h after challenge. Neither ethanol treatment nor a hyporesponsive TLR4 had significant effects on the cell numbers in the peritoneal cavity and spleen 2h postinfection. The suppressive effect of acute ethanol exposure on cytokine and chemokine production was more pronounced in the wild-type mice, but the untreated hyporesponsive mice produced less of most cytokines than untreated wild-type mice. The major conclusion of this study is that acute ethanol exposure suppresses pro-inflammatory cytokine production and that a hyporesponsive TLR4 (in C3H/HeJ mice) decreases pro-inflammatory cytokine levels, but the cytokines and other mediators induced through other receptors are sufficient to ultimately clear the infection but not enough to induce lethal septic shock. In addition, results reported here demonstrate previously unknown effects of acute ethanol exposure on leukemia inhibitory factor and eotaxin, and provide the first evidence that interleukin (IL)-9 is induced through TLR4 in vivo.

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.

Recruited exudative macrophages selectively produce CXCL10 after noninfectious lung injury

The chemokine, CXCL10, and its cognate receptor, CXCR3, are important mediators of the pathobiology of lung fibrosis. Macrophages are a known source of CXCL10, but their specific source in the lung is poorly defined due to incomplete characterization of macrophage subpopulations. We recently developed a novel flow cytometric approach that discriminates resident alveolar macrophages from recruited exudative macrophages (ExMacs) after infectious lung injury. We hypothesized that ExMacs are present after noninfectious lung injury with bleomycin, and are a source of CXCL10. We found that ExMacs are recruited to the lung after injury, peaking at Day 7, then maintained through Day 28. ExMac recruitment was significantly reduced, but not abolished, in CCR2 null mice. ExMacs, but not alveolar macrophages, produce CXCL10, both constitutively and after stimulation with hyaluronan (HA) fragments. Interestingly, ExMac stimulation with LPS resulted in complete suppression of CXCL10. In contrast, ExMacs produced TNF-α and CXCL2/MIP-2 (Macrophage Inflammatory Protein-2) after stimulation with both HA and LPS. ExMacs were present in CXCR3 null mice after bleomycin, but produced minimal CXCL10. This impairment was overcome by administration of exogenous IFN-γ or IFN-γ with HA. Collectively, these data suggest that ExMacs are recruited and maintained in the lung after noninfectious lung injury, are a source of a variety of cytokines, but importantly, are essential for the production of antifibrotic CXCL10. Understanding the contribution of ExMacs to the pathobiology of lung injury and repair could lead to new treatment options for fibrosing lung diseases.

Cellular and mitochondrial effects of alcohol consumption

Alcohol dependence is correlated with a wide spectrum of medical, psychological, behavioral, and social problems. Acute alcohol abuse causes damage to and functional impairment of several organs affecting protein, carbohydrate, and fat metabolism. Mitochondria participate with the conversion of acetaldehyde into acetate and the generation of increased amounts of NADH. Prenatal exposure to ethanol during fetal development induces a wide spectrum of adverse effects in offspring, such as neurologic abnormalities and pre- and post-natal growth retardation. Antioxidant effects have been described due to that alcoholic beverages contain different compounds, such as polyphenols as well as resveratrol. This review analyzes diverse topics on the alcohol consumption effects in several human organs and demonstrates the direct participation of mitochondria as potential target of compounds that can be used to prevent therapies for alcohol abusers.

Alcohol-use disorders in the critically ill patient

Alcohol abuse and dependence, referred to as alcohol-use disorders (AUDs), affect 76.3 million people worldwide and account for 1.8 million deaths per year. AUDs affect 18.3 million Americans (7.3% of the population), and up to 40% of hospitalized patients have AUDs. This review discusses the development and progression of critical illness in patients with AUDs. In contrast to acute intoxication, AUDs have been linked to increased severity of illness in a number of studies. In particular, surgical patients with AUDs experience higher rates of postoperative hemorrhage, cardiac complications, sepsis, and need for repeat surgery. Outcomes from trauma are worse for patients with chronic alcohol abuse, whereas burn patients who are acutely intoxicated may not have worse outcomes. AUDs are linked to not only a higher likelihood of community-acquired pneumonia and sepsis but also a higher severity of illness and higher rates of nosocomial pneumonia and sepsis. The management of sedation in patients with AUDs may be particularly challenging because of the increased need for sedatives and opioids and the difficulty in diagnosing withdrawal syndrome. The health-care provider also must be watchful for the development of dangerous agitation and violence, as these problems are not uncommonly seen in hospital ICUs. Despite studies showing that up to 40% of hospitalized patients have AUDs, relatively few guidelines exist on the specific management of the critically ill patient with AUDs. AUDs are underdiagnosed, and a first step to improving patient outcomes may lie in systematically and accurately identifying AUDs.

Cerebritis: an unusual complication of Klebsiella pneumoniae

Cerebritis is part of a continuum of brain infection and is difficult to diagnose. Cerebritis caused by Klebsiella in immunocompetent adults without predisposing factors such as neurosurgery or penetrating brain injury has not been reported before. We report a case of Klebsiella cerebritis in an adult patient with a proven extracranial focus of infection. We suggest considering cerebritis as a differential diagnosis for altered level of consciousness in patients of severe sepsis, even if an extracranial source of infection is proven.

ERK and not p38 pathway is required for IL-12 restoration of T cell IL-2 and IFN-gamma in a rodent model of alcohol intoxication and burn injury

Previous studies from our laboratory have shown that acute alcohol/ethanol (EtOH) intoxication combined with burn injury suppresses T cell IL-2 and IFN-gamma production by inhibiting p38 and ERK activation. Because IL-12 plays a major role in Th1 differentiation and IFN-gamma production, we examined whether diminished IL-2 and IFN-gamma production after EtOH plus burn injury resulted from a decrease in IL-12. Furthermore, we investigated whether IL-12 utilizes the p38/ERK pathway to modulate T cell IL-2 and IFN-gamma production after EtOH and burn injury. Male rats ( approximately 250 g) were gavaged with 5 ml of 20% EtOH 4 h before approximately 12.5% total body surface area burn or sham injury. Rats were sacrificed on day 1 after injury, and mesenteric lymph node T cells were isolated. T cells were stimulated with anti-CD3 in the absence or presence of rIL-12 (10 ng/ml) for 5 min and lysed. Lysates were analyzed for p38/ERK protein and phosphorylation levels using specific Abs and Western blot. In some experiments, T cells were cultured for 48 h with or without the inhibitors of p38 (10 microM SB203580/SB202190) or ERK (50 microM PD98059) to delineate the role of p38 and ERK in IL-12-mediated restoration of IL-2 and IFN-gamma. Our findings indicate that IL-12 normalizes both p38 and ERK activation in T cells, but the results obtained using p38 and ERK inhibitors indicate that the restoration of ERK plays a predominant role in IL-12-mediated restoration of T cell IL-2 and IFN-gamma production after EtOH and burn injury.

In vitro and in vivo models of acute alcohol exposure

Alcohol abuse is a global problem due to the financial burden on society and the healthcare system. While the harmful health effects of chronic alcohol abuse are well established, more recent data suggest that acute alcohol consumption also affects human wellbeing. Thus, there is a need for research models in order to fully understand the effect of acute alcohol abuse on different body systems and organs. The present manuscript summarizes the interdisciplinary advantages and disadvantages of currently available human and non-human models of acute alcohol abuse, and identifies their suitability for biomedical research.

A recent perspective on alcohol, immunity, and host defense

BACKGROUND

Multiple line of clinical and experimental evidence demonstrates that both acute, moderate, and chronic, excessive alcohol use result in various abnormalities in the functions of the immune system.

METHODS

Medline and PubMed databases were used to identify published reports with particular interest in the period of 2000-2008 in the subject of alcohol use, infection, inflammation, innate, and adaptive immunity.

RESULTS

This review article summarizes recent findings relevant to acute or chronic alcohol use-induced immunomodulation and its consequences on host defense against microbial pathogens and tissue injury. Studies with in vivo and in vitro alcohol administration are both discussed. The effects of alcohol on lung infections, trauma and burn injury, liver, pancreas, and cardiovascular diseases are evaluated with respect to the role of immune cells. Specific changes in innate immune response and abnormalities in adaptive immunity caused by alcohol intake are detailed.

CONCLUSION

Altered inflammatory cell and adaptive immune responses after alcohol consumption result in increased incidence and poor outcome of infections and other organ-specific immune-mediated effects.

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.

Ethanol exposure impairs LPS-induced pulmonary LIX expression: alveolar epithelial cell dysfunction as a consequence of acute intoxication

BACKGROUND

Alcohol intoxication impairs innate immune responses to bacterial pneumonia, including neutrophil influx. Lipopolysaccharide (LPS)-induced chemokine (LIX or CXCL5) is a recently described chemokine produced by type-II alveolar epithelial (AE2) cells which facilitates neutrophil recruitment. The effect of acute alcohol intoxication on AE2 cell expression of LIX is unknown.

METHODS

C57BL/6 mice were given an intraperitoneal (i.p.) injection of ethanol (4 g/kg) or saline 30 minutes prior to intratracheal (i.t.) injection with 10 mug Escherichia coli LPS. In vitro stimulation of primary AE2 cells or murine AE2 cell line MLE-12 was performed with LPS and tumor necrosis factor-alpha (TNF-alpha).

RESULTS

LIX protein is readily detectable in the lung but not in plasma following LPS administration, demonstrating "compartmentalization" of this chemokine during pulmonary challenge. In contrast to the CXC chemokines keratinocyte-derived chemokine and macrophage inflammatory protein-2, which are abundantly expressed in both lung tissue and alveolar macrophages, LIX expression is largely confined to the lung parenchyma. Compared to controls, intoxicated animals show a decrease in LIX and neutrophil number in bronchoalveolar lavage fluid following LPS challenge. Ethanol inhibits LIX at the transcriptional level. In vitro studies show that LPS and TNF-alpha are synergistic in inducing LIX by either primary AE2 or MLE-12 cells. Acute ethanol exposure potently and dose-dependently inhibits LIX expression by AE2 cells. Activation of nuclear factor-kappaB is critical to LIX expression in MLE-12 cells, and acute ethanol treatment interferes with early activation of this pathway as evidenced by impairing phosphorylation of p65 (RelA). Inhibition of p38 mitogen-activated protein kinase signaling, but not ERK1/2 activity, in MLE-12 cells by acute alcohol is likely an important cause of decreased LIX expression during challenge.

CONCLUSIONS

These data demonstrate direct suppression of AE2 cell innate immune function by ethanol and add to our understanding of the mechanisms by which acute intoxication impairs the lung's response to microbial challenge.

Acute alcohol intake induces SOCS1 and SOCS3 and inhibits cytokine-induced STAT1 and STAT3 signaling in human monocytes

BACKGROUND

Acute alcohol consumption is associated with induction of immuno-inhibitory cytokines and down-regulation of pro-inflammatory responses to various pathogens. We previously reported that alcohol activates janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling leading to IL-10 induction. The JAK-STAT pathway also activates its own negative regulators, suppressors of cytokine signaling (SOCS) 1 and SOCS3. SOCS proteins are inducible inhibitors that negatively regulate STAT3/STAT1 signaling pathways induced by cytokines, IL-6 or IFNs. Here we aimed to explore the effect of acute alcohol on induction of SOCS1/SOCS3 and regulation of STAT3/STAT1 pathways induced by IL-6 or IFNs in human monocytes.

METHODS

Blood samples from normal volunteers were collected before and 24 hours after consumption of 2 ml vodka/kg body weight. For in vitro experiments human monocytes were pretreated with ethanol (EtOH) followed by stimulation with cytokines; proteins were analyzed by Western blot, nuclear protein binding to DNA by EMSA, and RNA by real time PCR.

RESULTS

Acute in vivo or in vitro alcohol treatment increased both SOCS1 and SOCS3 RNA expression in monocytes. Alcohol treatment resulted in increased STAT3 and STAT1 DNA binding capacity. Activation of both STAT1 and STAT3 has been shown to induce SOCS1/3. We hypothesized that induction of SOCS proteins by alcohol in turn may lead to modulation of cytokine signaling through STAT1 and STAT3. Indeed, we observed significant down-regulation of IL-6-, IFNalpha- and IFNgamma-induced STAT1 DNA binding as well as inhibition of IL-6- and IFNgamma-induced STAT3 when alcohol was added to monocytes 3 hours prior to the cytokine stimulation. Consistent with inhibition of IL-6-induced STAT3 DNA binding in alcohol-pretreated cells, the levels of IL-6-dependent genes, MCP-1 and ICAM-1, was reduced after IL-6 stimulation. Similar to EtOH alone, combined EtOH+IL-6 simulation resulted in increased expression of both SOCS3 and SOCS1 genes.

CONCLUSION

While acute alcohol treatment alone activates STAT1/3 signaling pathways and induces SOCS3 and SOCS1 levels in monocytes, alcohol also leads to down-regulation of IL-6-, IFNalpha-, and IFNgamma-induced signaling via STAT1/STAT3 pathways, likely through excessive SOCS activation.