Chronic ethanol intake and burn injury: evidence for synergistic alteration in gut and immune integrity

Base editing of haematopoietic stem cells rescues sickle cell disease in mice

Sickle cell disease (SCD) is caused by a mutation in the β-globin gene HBB1. We used a custom adenine base editor (ABE8e-NRCH)2,3 to convert the SCD allele (HBBS) into Makassar β-globin (HBBG), a non-pathogenic variant4,5. Ex vivo delivery of mRNA encoding the base editor with a targeting guide RNA into haematopoietic stem and progenitor cells (HSPCs) from patients with SCD resulted in 80% conversion of HBBS to HBBG. Sixteen weeks after transplantation of edited human HSPCs into immunodeficient mice, the frequency of HBBG was 68% and hypoxia-induced sickling of bone marrow reticulocytes had decreased fivefold, indicating durable gene editing. To assess the physiological effects of HBBS base editing, we delivered ABE8e-NRCH and guide RNA into HSPCs from a humanized SCD mouse6 and then transplanted these cells into irradiated mice. After sixteen weeks, Makassar β-globin represented 79% of β-globin protein in blood, and hypoxia-induced sickling was reduced threefold. Mice that received base-edited HSPCs showed near-normal haematological parameters and reduced splenic pathology compared to mice that received unedited cells. Secondary transplantation of edited bone marrow confirmed that the gene editing was durable in long-term haematopoietic stem cells and showed that HBBS-to-HBBG editing of 20% or more is sufficient for phenotypic rescue. Base editing of human HSPCs avoided the p53 activation and larger deletions that have been observed following Cas9 nuclease treatment. These findings point towards a one-time autologous treatment for SCD that eliminates pathogenic HBBS, generates benign HBBG, and minimizes the undesired consequences of double-strand DNA breaks.

Microbiota and Alcohol Use Disorder: Are Psychobiotics a Novel Therapeutic Strategy?

In recent years, there has been an exciting focus of research attempting to understand neuropsychiatric disorders from a holistic perspective in order to determine the role of gut microbiota in the aetiology and pathogenesis of such disorders. Thus, the possible therapeutic benefits of targeting gut microbiota are being explored for conditions such as stress, depression or schizophrenia. Growing evidence indicates that there is bidirectional communication between gut microbiota and the brain that has an effect on normal CNS functioning and behavioural responses. Alcohol abuse damages the gastrointestinal tract, alters gut microbiota and induces neuroinflammation and cognitive decline. The relationship between alcohol abuse and hypothalamic-pituitary-adrenal axis activation, inflammation and immune regulation has been well documented. In this review, we explore the connection between microbiota, brain function and behaviour, as well as the mechanisms through which alcohol induces microbiota dysbiosis and intestinal barrier dysfunction. Finally, we propose the study of psychobiotics as a novel pharmaceutical strategy to treat alcohol use disorders.

Influence of experimental alcoholism on the repair process of bone defects filled with beta-tricalcium phosphate

This study evaluated the effect of ethanol on the repair in calvaria treated with beta-tricalcium phosphate (β-TCP). Forty rats were distributed into 2 groups: Water group (CG, n = 20) and Alcohol Group (AG, n = 20), which received 25% ethanol ad libitum after an adaptation period of 3 weeks. After 90 days of liquid diet, the rats were submitted to a 5.0 mm bilateral craniotomy in the parietal bones; the left parietal was filled with β-TCP (CG-TCP and AG-TCP) and the contralateral only with blood clot (CG-Clot and AG-Clot). The animals were killed after 10, 20, 40 and 60 days. The groups CG-Clot and AG-Clot showed similar pattern of bone formation with a gradual and significant increase in the amount of bone in CG-Clot (22.17 ± 3.18 and 34.81 ± 5.49) in relation to AG-Clot (9.35 ± 5.98 and 21.65 ± 6.70) in periods of 20-40 days, respectively. However, in the other periods there was no statistically significant difference. Alcohol ingestion had a negative influence on bone formation, even with the use of β-TCP, exhibiting slow resorption and replacement by fibrous tissue, with 16% of bone formation within 60 days in AG-TCP, exhibiting immature bone tissue with predominance of disorganized collagen fibers. Defects in CG-TCP showed bone tissue with predominance of lamellar arrangement filling 39% of the original defect. It can be concluded that chronic ethanol consumption impairs the ability to repair bone defects, even with the use of a β-TCP biomaterial.

Intestine immune homeostasis after alcohol and burn injury

Traumatic injury remains one of the most prevalent reasons for patients to be hospitalized. Burn injury accounts for 40,000 hospitalizations in the United States annually, resulting in a large burden on both the health and economic system and costing millions of dollars every year. The complications associated with postburn care can quickly cause life-threatening conditions including sepsis and multiple organ dysfunction and failure. In addition, alcohol intoxication at the time of burn injury has been shown to exacerbate these problems. One of the biggest reasons for the onset of these complications is the global suppression of the host immune system and increased susceptibility to infection. It has been hypothesized that infections after burn and other traumatic injury may stem from pathogenic bacteria from within the host's gastrointestinal tract. The intestine is the major reservoir of bacteria within the host, and many studies have demonstrated perturbations of the intestinal barrier after burn injury. This article reviews the findings of these studies as they pertain to changes in the intestinal immune system after alcohol and burn injury.

Dietary diallyl disulfide supplementation attenuates ethanol-mediated pulmonary vitamin D speciate depletion in C57Bl/6 mice

Background

Slightly more than 5 % of the United States population heavily consumes ethanol, i.e., more than 14 drinks for men and 7 drinks for women a week. Chronic ethanol consumption can result in increased liver disease, reduced recovery from burn injury, and more frequent and severe respiratory infections. Chronic ethanol over-consumption also leads to vitamin D dysmetabolism and depletion. Vitamin D is a fat-soluble pro-hormone that regulates musculoskeletal health, cellular proliferation/differentiation, and innate and adaptive immune response.

Methods

In this study, C57BL/6 mice were fed 20 % ethanol in their water ad libitum for 7 weeks. Some mice were fed either a standard chow or a modified diet containing 0.15 μg/day of diallyl disulfide (DADS). Whole blood, lung tissue, and bronchial alveolar lavage fluid (BALF) were collected at sacrifice and analyzed for 25(OH) D₃, 1,25 (OH)₂D₃, vitamin D receptor VDR, CYP2E1, and CYP27B1 levels.

Results

Ethanol reduced 25(OH) D₃ and 1,25 (OH)₂D₃ in lung tissue and BALF on average 31 %. The largest ethanol-mediated reduction was in the 1,25 (OH)₂D₃ (42 %) measured in the BALF. Dietary supplementation of DADS restored BALF and lung tissue protein of 25(OH) D₃ and 1,25(OH)₂D₃ to control levels. Chronic ethanol consumption also resulted in tissue increases of vitamin D response (VDR) protein, Cyp2E1, and reductions in vitamin D-activating enzyme CYP27B1. All three of these effects were attenuated by dietary supplementation of DADS.

Conclusions

In conclusion, the pulmonary metabolic disturbances mediated by chronic ethanol consumption as measured by 1,25(OH)₂D₃ protein levels, epithelial lining fluid, and lung tissue can be ameliorated by dietary supplementation of DADS in C57BL/6 mice.

Acute exercises induce disorders of the gastrointestinal integrity in a murine model

PURPOSE

Many endurance athletes complain about gastrointestinal (GI) symptoms. It is assumed that exercise-induced shift of perfusion with consecutive hypoperfusion of the enteral vascular system leads to an increased GI permeability and tissue damage. Therefore, the aim of the study was to investigate permeability, apoptosis, electrogenic ion transport (Isc), and tissue conductance (Gt) of the small intestine in a murine exercise model.

METHODS

After spirometry, male Swiss CD-1 mice were subjected to an intensive treadmill exercise (80% VO2max). Sedentary mice served as controls. The small intestine was removed at several time intervals post-exercise. Apoptotic cells were determined by the TUNEL method, while fluorescein isothiocyanate dextran permeation indicated intestinal permeability. The Gt and Isc measurements were carried out in a modified Ussing chamber.

RESULTS

Apoptosis of epithelial cells increased continuously until 24 h post exercise (0.8 ± 0.42 versus 39.2 ± 26.0%; p < 0.05). Compared with the control group the permeability increased 2 h after exercise (0.47 ± 0.07 versus 0.67 ± 0.14 FU/min; p < 0.05). Isc measurements of the ileum were augmented after 24 h (3.33 ± 0.56 versus 5.77 ± 1.16 μEq/h/cm(2); p < 0.05). At this time the Gt increased as well (28.8 ± 3.37 versus 32.5 ± 2.59 mS/cm(2); p < 0.05).

CONCLUSION

In the murine exercise model there is evidence that after intense endurance exercise repair processes occur in small intestinal epithelial cells, which affect permeability, Gt, and Isc. The formation of lamellipodia to close the "leaky" tight junctions caused by apoptosis might be an underlying mechanism.

Ascorbic acid suppresses endotoxemia and NF-κB signaling cascade in alcoholic liver fibrosis in guinea pigs: a mechanistic approach

Alcohol consumption increases the small intestinal bacterial overgrowth (SIBO) and intestinal permeability of endotoxin. The endotoxin mediated inflammatory signaling plays a major role in alcoholic liver fibrosis. We evaluated the effect of ascorbic acid (AA), silymarin and alcohol abstention on the alcohol induced endotoxemia and NF-κB activation cascade pathway in guinea pigs (Cavia porcellus). Guinea pigs were administered ethanol at a daily dose of 4g/kg b.wt for 90days. After 90days, ethanol administration was stopped. The ethanol treated animals were divided into abstention, silymarin (250mg/kg b.wt) and AA (250mg/kg b.wt) supplemented groups and maintained for 30days. The SIBO, intestinal permeability and endotoxin were significantly increased in the ethanol group. The mRNA expressions of intestinal proteins claudin, occludin and zona occludens-1 were significantly decreased in ethanol group. The mRNA levels of inflammatory receptors, activity of IKKβ and the protein expressions of phospho-IκBα, NF-κB, TNF-α, TGF-β1 and IL-6 were also altered in ethanol group. The expressions of fibrosis markers α-SMA, α1 (I) collagen and sirius red staining in the liver revealed the induction of fibrosis. But the supplementation of AA could induce greater reduction of ethanol induced SIBO, intestinal barrier defects, NF-κB activation and liver fibrosis than silymarin. The possible mechanism may be the inhibitory effect of AA on SIBO, intestinal barrier defect and IKKβ, which decreased the activation of NF-κB and synthesis of cytokines. This might have led to suppression of HSCs activation and liver fibrosis.

Ethanol metabolism and its effects on the intestinal epithelial barrier

Ethanol is widely consumed and is associated with an increasing global health burden. Several reviews have addressed the effects of ethanol and its oxidative metabolite, acetaldehyde, on the gastrointestinal (GI) tract, focusing on carcinogenic effects or alcoholic liver disease. However, both the oxidative and the nonoxidative metabolites of ethanol can affect the epithelial barrier of the small and large intestines, thereby contributing to GI and liver diseases. This review outlines the possible mechanisms of ethanol metabolism as well as the effects of ethanol and its metabolites on the intestinal barrier. Limited studies in humans and supporting in vitro data have indicated that ethanol as well as mainly acetaldehyde can increase small intestinal permeability. Limited evidence also points to increased colon permeability following exposure to ethanol or acetaldehyde. In vitro studies have provided several mechanisms for disruption of the epithelial barrier, including activation of different cell-signaling pathways, oxidative stress, and remodeling of the cytoskeleton. Modulation via intestinal microbiota, however, should also be considered. In conclusion, ethanol and its metabolites may act additively or even synergistically in vivo. Therefore, in vivo studies investigating the effects of ethanol and its byproducts on permeability of the small and large intestines are warranted.

Bacterial translocation and changes in the intestinal microbiome associated with alcoholic liver disease

Alcoholic liver disease progresses through several stages of tissue damage, from simple steatosis to alcoholic hepatitis, fibrosis, or cirrhosis. Alcohol also affects the intestine, increases intestinal permeability and changes the bacterial microflora. Liver disease severity correlates with levels of systemic bacterial products in patients, and experimental alcoholic liver disease is dependent on gut derived bacterial products in mice. Supporting evidence for the importance of bacterial translocation comes from animal studies demonstrating that intestinal decontamination is associated with decreased liver fibrogenesis. In addition, mice with a gene mutation or deletion encoding receptors for either bacterial products or signaling molecules downstream from these receptors, are resistant to alcohol-induced liver disease. Despite this strong association, the exact molecular mechanism of bacterial translocation and of how changes in the intestinal microbiome contribute to liver disease progression remains largely unknown. In this review we will summarize evidence for bacterial translocation and enteric microbial changes in response to alcoholic liver injury and chronic alcoholic liver disease. We will further describe consequences of intestinal dysbiosis on host biology. We finally discuss how therapeutic interventions may modify the gastrointestinal microflora and prevent or reduce alcoholic liver disease progression.

Alteration in intestine tight junction protein phosphorylation and apoptosis is associated with increase in IL-18 levels following alcohol intoxication and burn injury

Intestinal mucosal barrier is the first line of defense against bacteria and their products originating from the intestinal lumen. We have shown a role for IL-18 in impaired gut barrier function following acute alcohol (EtOH) intoxication combined with burn injury. To further delineate the mechanism, this study examined whether IL-18 alters intestine tight junction proteins or induces mucosal apoptosis under these conditions. To accomplish this, rats were gavaged with EtOH (3.2g/kg) prior to ~12.5% total body surface area burn or sham injury. One day after injury, EtOH combined with burn injury resulted in a significant decrease in total occludin protein and its phosphorylation in small intestine compared to either EtOH or burn injury alone. There was no change in claudin-1 protein content but its phosphorylation on tyrosine was decreased following EtOH and burn injury. This was accompanied with an increase in mucosal apoptosis (p<0.05). The treatment of rats with anti-IL-18 antibody at the time of burn injury prevented intestine apoptosis and normalized tight junction proteins following EtOH and burn injury. Altogether, these findings suggest that IL-18 modulates tight junction proteins and cause apoptosis leading to impaired intestinal mucosal integrity following EtOH intoxication combined with burn injury.

Macrophage phagocytosis: effects of environmental pollutants, alcohol, cigarette smoke, and other external factors

The ability of a pathogen to evade host immunity successfully, in contrast to the host's capacity to defend itself against a foreign invader, is a complex struggle, in which eradication of infection is dictated by a robust immunologic response. Often, there are external factors that can alter the outcome by tipping the scale to benefit pathogen establishment rather than resolution by the host's defense system. These external sources, such a cigarettes, alcohol, or environmental pollutants, can negatively influence the effectiveness of the immune system's response to a pathogen. The observed suppression of immune function can be attributed to dysregulated cytokine and chemokine production, the loss of migratory potential, or the inability to phagocytose pathogens by immune cells. This review will focus on the mechanisms involved during the toxin-induced suppression of phagocytosis. The accumulated data support the importance of studying the mechanisms of phagocytosis following exposure to these factors, in that this effect alone cannot only leave the host susceptible to infection but also promote alterations in many other macrophage functions necessary for pathogen clearance and restoration of homeostasis.

Alcohol, burn injury, and the intestine

A significant number of burn and other traumatic injuries are reported to occur under the influence of alcohol (EtOH) intoxication. Despite this overwhelming association between EtOH intoxication and injury, relatively little attention has been paid to determining the role of EtOH in post-injury pathogenesis. This article reviews studies which have evaluated the impact of EtOH on post-burn intestinal immunity and barrier functions. The findings from these studies suggest that while a smaller burn injury by itself may not have an adverse effect on host defense, when combined with prior EtOH intoxication it may become detrimental. Experimental data from our laboratory further supports the notion that EtOH intoxication before burn injury suppresses intestinal immune defense, impairs gut barrier functions, and increases bacterial growth. This results in increased bacterial translocation which may contribute to post injury pathogenesis. Altogether, the studies reviewed in this article suggest that EtOH intoxication at the time of injury is a risk factor, and therefore blood EtOH should be checked in burn/trauma patients at the time of hospital admission.

The association between blood alcohol level and infectious complications among burn patients

Approximately 50% of fatal and 15% of nonfatal burn-injured patients have detectable blood alcohol content (BAC) at the time of admission, and it is hypothesized that alcohol exacerbates burn-related immunosuppression. The purpose of this study was to evaluate the association between BAC and infectious complications in burn patients. The study population consisted of 1161 burn patients admitted to a large academic burn center between January 1998 and June 2007. Patients were categorized into no BAC (0.0 g/100 ml), low/moderate BAC (>0.0 and <0.1 g/100 ml) and high BAC (> or =0.1 g/100 ml) groups based on BAC at time of admission. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated for associations between pneumonia, sepsis, urinary tract infection, line infection, and wound infection and BAC, adjusted for total burn surface area and inhalation injury. Relative to no BAC patients, both low/moderate and high BAC patients had nonsignificantly increased risk for most infectious complications. High BAC patients were at significantly increased risk for any infectious complication (RR 2.06, CI 1.25-3.41) and pneumonia (RR 2.06, CI 1.04-4.09) and a nonsignificantly increased risk of urinary tract infection (RR 2.12, CI 0.0.94-4.78). Results suggest that preinjury alcohol consumption places patients at an increased risk for infectious complications, most notably pneumonia. Further studies examining the relationship between alcohol and pneumonia among burn patients will help elucidate the reason for the increased risk observed in the current study and suggest ways to prevent infection for this particular subgroup of burn patients.

Alcohol, intestinal bacterial growth, intestinal permeability to endotoxin, and medical consequences: summary of a symposium

This report is a summary of the symposium on Alcohol, Intestinal Bacterial Growth, Intestinal Permeability to Endotoxin, and Medical Consequences, organized by National Institute on Alcohol Abuse and Alcoholism, Office of Dietary Supplements, and National Institute of Diabetes and Digestive and Kidney Diseases of National Institutes of Health in Rockville, Maryland, October 11, 2006. Alcohol exposure can promote the growth of Gram-negative bacteria in the intestine, which may result in accumulation of endotoxin. In addition, alcohol metabolism by Gram-negative bacteria and intestinal epithelial cells can result in accumulation of acetaldehyde, which in turn can increase intestinal permeability to endotoxin by increasing tyrosine phosphorylation of tight junction and adherens junction proteins. Alcohol-induced generation of nitric oxide may also contribute to increased permeability to endotoxin by reacting with tubulin, which may cause damage to microtubule cytoskeleton and subsequent disruption of intestinal barrier function. Increased intestinal permeability can lead to increased transfer of endotoxin from the intestine to the liver and general circulation where endotoxin may trigger inflammatory changes in the liver and other organs. Alcohol may also increase intestinal permeability to peptidoglycan, which can initiate inflammatory response in liver and other organs. In addition, acute alcohol exposure may potentiate the effect of burn injury on intestinal bacterial growth and permeability. Decreasing the number of Gram-negative bacteria in the intestine can result in decreased production of endotoxin as well as acetaldehyde which is expected to decrease intestinal permeability to endotoxin. In addition, intestinal permeability may be preserved by administering epidermal growth factor, l-glutamine, oats supplementation, or zinc, thereby preventing the transfer of endotoxin to the general circulation. Thus reducing the number of intestinal Gram-negative bacteria and preserving intestinal permeability to endotoxin may attenuate alcoholic liver and other organ injuries.

Heme oxygenase-1 protects against neutrophil-mediated intestinal damage by down-regulation of neutrophil p47phox and p67phox activity and O2- production in a two-hit model of alcohol intoxication and burn injury

Heme oxygenase-1 (HO-1) has been demonstrated to protect against tissue injury. Furthermore, HO-1 is also shown to be antioxidant. Our recent findings indicate that acute alcohol (EtOH) intoxication exacerbates postburn intestinal and lung tissue damage, and this was found to be neutrophil dependent. Because neutrophil-mediated tissue injury involves the release of superoxide anions (O(2)(-)), the present study examined the role of HO-1 in neutrophil O(2)(-) production following EtOH and burn injury. Furthermore, we investigated whether HO-1 antioxidant properties are mediated via modulation of p47(phox) and/or p67(phox) proteins. Male rats (approximately 250 g) were gavaged with EtOH to achieve a blood EtOH level of approximately 100 mg/dL before burn or sham injury (approximately 12.5% total body surface area). Some rats were treated with HO-1 activator cobalt protoporphyrin IX chloride (Copp; 25 mg/kg body weight) at the time of injury. On day 1 after injury, we found that EtOH combined with burn injury significantly increased neutrophil O(2)(-) production and p47(phox) and p67(phox) activation and decreased caspase-3 activity and apoptosis. This was accompanied with a decrease in neutrophil HO-1 levels. The treatment of animals with HO-1 activator Copp normalized neutrophil HO-1, O(2)(-), p47(phox), and p67(phox) following EtOH and burn injury. The expression of caspase-3, however, was further decreased in Copp-treated sham and EtOH plus burn groups. Moreover, Copp treatment also prevented the increase in intestinal edema and permeability following EtOH and burn injury. Altogether, these findings provide a new insight into the mechanism by which HO-1 regulates neutrophil O(2)(-) production and protect the intestine from damage following EtOH and burn injury.

Inhibition of protein tyrosine phosphatases prevents mesenteric lymph node T-cell suppression following alcohol intoxication and burn injury

Previously, we have shown that acute alcohol (EtOH) intoxication before burn injury potentiates the suppression of mesenteric lymph node T-cell effector responses. Moreover, the suppression in T-cell was accompanied with a decrease in p-38 and extracellular-signal-regulated kinase (ERK) activation. This study examined the role of protein tyrosine phosphatases (PTP) in suppressed T-cell p-38, ERK, and cytokine production after EtOH intoxication and burn injury. A blood EtOH level of approximately 100 mg/dl in male rats (approximately 250 g) was achieved by gavaging animals with 5 ml of 20% EtOH suspension 4 hours before burn or sham injury (approximately 12.5% or 25% total body surface area [TBSA]). One day after injury, rats were killed and mesenteric lymph node T-cell cytokine (IL-2/IFN-gamma) production, p-38, and ERK activation were measured. As compared with shams, there was a significant decrease in T-cell cytokine production after 25% and not 12.5% TBSA burn injury. However, T-cell IL-2/IFN-gamma levels were significantly decreased in rats receiving a combined insult of EtOH and burn injury regardless of the percentage of burn area. Furthermore, we found a significant decrease in p-38 and ERK-1/2 phosphorylation in T-cells of rats receiving a combined insult of EtOH and 12.5% TBSA burn compared with shams. Treatment of cells with PTP inhibitor pervanadate (10 muM) prevented T-cell p-38/ERK suppression. The suppression in IL-2/IFN-gamma production was also attenuated in T-cells cultured in the presence of pervanadate. These findings suggest that an increase in PTP activity may contribute to T-cell suppression after EtOH intoxication and burn injury.

Organ-specific inflammation following acute ethanol and burn injury

Clinical and experimental evidence demonstrates that ethanol exposure prior to injury alters local and systemic inflammatory responses, increasing morbidity and mortality. Moreover, the aberrant inflammatory responses can directly and indirectly lead to the poor prognosis after injury by altering leukocyte infiltration into the wound site and remote organs and by suppressing immunity leading to increased susceptibility to opportunistic infections. Recent studies from our laboratory have focused on inflammatory responses at the wound site and in other distal organs after exposure to acute ethanol and burn injury. This combined insult leads to increased mortality after dermal or intratracheal pseudomonas infection, relative to infected mice given ethanol or burn injury alone. The increased mortality in mice given ethanol and burn injury parallels elevated serum levels of proinflammatory cytokines, IL-6 and TNF-alpha, marked infiltration of leukocytes into the lung and gut, as well as immunosuppression at the sites of infection. Bacterial translocation from the gut is likely to be responsible, in part, for the aberrant accumulation of leukocytes in the lungs of ethanol-exposed, burn-injured mice. Additionally, other factors, such as expression of adhesion molecules, increased chemokine production, and leakiness of the vascular endothelium, may also be involved.

Sex differences and estrogen modulation of the cellular immune response after injury

Cell-mediated immunity is extremely important for resolution of infection and for proper healing from injury. However, the cellular immune response is dysregulated following injuries such as burn and hemorrhage. Sex hormones are known to regulate immunity, and a well-documented dichotomy exists in the immune response to injury between the sexes. This disparity is caused by differences in immune cell activation, infiltration, and cytokine production during and after injury. Estrogen and testosterone can positively or negatively regulate the cellular immune response either by aiding in resolution or by compounding the morbidity and mortality. It is apparent that the hormonal dysregulation is dependent not only on the type of injury sustained but also the amount of circulating hormones. Therefore, it may be possible to design sex-specific therapies to improve immunological function and patient outcome.

A role for corticosterone in impaired intestinal immunity and barrier function in a rodent model of acute alcohol intoxication and burn injury

Alcohol (EtOH) intoxication and burn injury independently activate hypothalamic-pituitary-adrenal (HPA) axis, and glucocorticoids, the end product of the HPA axis, play a role in shaping the immune response under those conditions. By utilizing a rat model of acute EtOH intoxication and burn injury, studies in our laboratory have investigated the role of corticosterone (i.e., glucocorticoids in rodents) in altered intestinal immunity and barrier function following a combined insult of EtOH and burn injury. Results from these studies suggest that EtOH intoxication prior to burn injury augments corticosterone release, which in turn suppresses intestinal T cell function by inhibiting mitogen-activated protein kinase (i.e., p38 and ERK) pathway. Furthermore, we found that corticosterone does not directly alter the intestinal barrier function; rather, it up-regulates interleukin-18, which then directly or indirectly contributes to impaired intestinal barrier function. The loss of intestinal immunity/barrier function may result in increased bacterial translocation and thereby contribute to postinjury pathogenesis, leading to sepsis and organ dysfunction in burn patients as well as in patients with a history of EtOH intoxication.

Epidemiology of sepsis: race, sex, and chronic alcohol abuse

The annual incidences of severe sepsis in several industrialized nations have recently been reported to be 50-100 cases per 100,000 persons. These numbers exceed the estimated rates for other diseases that hold a heightened public awareness, including breast cancer and acquired immune deficiency syndrome. There are also sex and race differences in the incidence of sepsis. Men are more likely than women to develop sepsis, with a mean annual relative risk of 1.28. Nonwhites are nearly twice as likely to develop sepsis as whites. These race and sex disparities in the incidence of sepsis are likely explained by differences in a variety of factors, including the presence of comorbid conditions. For example, chronic alcohol abuse is associated with a persistent fever, delayed resolution of symptoms, increased rates of bacteremia, increased use of intensive care, prolonged duration of hospital stay, and increased cost of hospitalization for infected patients.

Protective effect of ethyl pyruvate on msP rat leukocytes damaged by alcohol intake

Alcohol consumption for long periods negatively influences physiological functions of many cells, and leads to organ damage. Reactive oxygen and nitrogen species produced by ethanol metabolism cause adverse effects that might be alleviated by simultaneous treatment with various antioxidants. Here, the ability of ethyl pyruvate (EP) to reduce ethanol-induced oxidative stress was evaluated. Chemiluminescence studies show that EP has a higher capacity than pyruvate to scavenge hydrogen peroxide and superoxide anions. In order to evaluate whether EP can exert a protective effect against ethanol, rats were offered 10% ethanol in drinking burettes, containing or not different concentrations of EP (0.3%, 1% and 3%). The comet assay was employed to quantify the alcohol-induced DNA damage in rat lymphocytes. This test is a promising tool for the estimation of DNA damage at the single cell level. A significant protective effect of EP was observed in rat groups treated with this antioxidant, compared with those drinking only ethanol. Since EP has been shown to decrease the expression of numerous pro-inflammatory mediators, the monocyte respiratory burst was evaluated. The activation of monocyte NADPH oxidase by phorbol esters (PMA) showed that superoxide anion production was higher in the ethanol group than in the control group. The presence of EP considerably reduced superoxide anion production. In conclusion, hypotheses on possible mechanisms of action of EP on rat white blood cells are proposed.

Chronic alcohol consumption results in higher simian immunodeficiency virus replication in mucosally inoculated rhesus macaques

The influence of alcohol consumption on HIV pathogenesis is not well understood. In this study we used the SIV/macaque model of HIV infection to study the influence of chronic binge alcohol consumption on simian immunodeficiency virus (SIV) infection. Rhesus macaques were fed alcohol or isocaloric amounts of sucrose via indwelling intragastric catheters and then inoculated with SIVmac251 by the rectal route. Real-time RTPCR for SIV gag mRNA showed significantly higher plasma viral copies in alcohol-consuming macaques at 4 and 6 weeks pi, compared with sucrose controls. The viral copies were 1 to 2 logs higher in these animals. The percentage of CD8+ lymphocytes in the duodenum of alcohol-consuming macaques was significantly lower than in sucrose-consuming macaques both before infection as well as at different time points postinfection. Also, the percentage of CD4+CD3+ lymphocytes in the intestines was significantly higher in alcohol-consuming macaques before infection. These findings suggest that a higher percentage of SIV target cells (CD4) in the gut coupled with lower percentages of CD8 cells, which could be important in controlling virus replication, may be responsible for the higher SIV loads observed in alcohol-consuming macaques.

A role of PP1/PP2A in mesenteric lymph node T cell suppression in a two-hit rodent model of alcohol intoxication and injury

This study examined the role of protein phosphatase type-1 (PP1), type-2A (PP2A), and mitogen-activated protein kinase phosphatase-1 (MKP-1) in altered mesenteric lymph node (MLN) T cell function in a two-hit model of alcohol (EtOH) intoxication and burn injury. Male rats (250 g) were gavaged with EtOH to achieve a blood EtOH level of approximately 100 mg/dL prior to burn or sham injury (25% total body surface area). MLN T cells harvested 24 h after injury show a significant decrease in p38 and extracellular signal-regulated kinase (ERK)-1/2 phosphorylation in T cells from rats receiving a combined insult of EtOH intoxication and burn injury compared with rats receiving EtOH intoxication or burn injury alone. Treatment of cells with inhibitors of PP1/PP2A [calyculin A (CA) and okadaic acid (OA)] prevented the suppression in T cells p38 and ERK-1/2 activation. In addition, the suppression in interleukin-2 and interferon-gamma production was attenuated in T cells cultured in the presence of CA and OA. MKP-1 inhibitor triptolide did not prevent the suppression in T cells p38/ERK-1/2 and cytokine production. Furthermore, there was a significant decrease in PP1alpha phosphorylation (Thr320) and an increase in PP2A (Tyr307) phosphorylation in T cells following a combined insult of EtOH intoxication and burn injury. As phosphorylation of PP1 at Thr320 and PP2A at Tyr307 led to an inhibition of their enzymatic activities, the decrease in the PP1alpha phosphorylation correlates with an increase in its enzyme activity. Thus, these results suggest that activation of PP1 is likely to play a predominant role in T cell suppression following a combined insult of EtOH intoxication and burn injury.

Chronic alcohol consumption results in higher simian immunodeficiency virus replication in mucosally inoculated rhesus macaques

The influence of alcohol consumption on HIV pathogenesis is not well understood. In this study we used the simian immunodeficiency virus (SIV)/macaque model of HIV infection to study the influence of chronic binge alcohol consumption on SIV infection. Rhesus macaques were fed alcohol or isocaloric amounts of sucrose via indwelling intragastric catheters and then inoculated with SIVmac251 by the rectal route. Real-time RT-PCR for SIV gag mRNA showed significantly higher plasma viral copies in alcohol-consuming macaques at 4 and 6 weeks pi, compared with sucrose controls. The viral copies were 1 to 2 logs higher in these animals. The percentage of CD8+ lymphocytes in the duodenum of alcohol-consuming macaques was significantly lower than in sucrose-consuming macaques both before infection as well as at different time points postinfection. Also, the percentage of CD4(+)CD3+ lymphocytes in the intestines was significantly higher in alcohol-consuming macaques before infection. These findings suggest that a higher percentage of SIV target cells (CD4) in the gut coupled with lower percentages of CD8 cells, which could be important in controlling virus replication, may be responsible for the higher SIV loads observed in alcohol-consuming macaques.

Role of the gastrointestinal tract in burn sepsis

During the last 50 years, our understanding of the role of the gastrointestinal tract as a first-line defense against the development of postburn sepsis has increased dramatically. Starting with the concept of that gut-derived bacteria cause distant injury, investigators have delineated a complex series of physical changes in the barrier of the gastrointestinal tract. Along with an understanding of these physical changes has come an appreciation of the role of the immune system in modulating postburn organ failure. Importantly, recent investigations into the role of mesenteric lymph have fundamentally changed the paradigm of organ failure and have implicated the gut as a cytokine-secreting organ. This article traces the development of key concepts in the study of burn sepsis and their clinical implications.

Inhibition of IL-18 reduces myeloperoxidase activity and prevents edema in intestine following alcohol and burn injury

Previous studies have shown that alcohol (EtOH) ingestion before burn injury impaired intestinal barrier and immune function. This study determined whether EtOH and burn injury up-regulate interleukin (IL)-18 and whether IL-18 up-regulation following EtOH and burn injury is a cause for neutrophil recruitment and increased intestinal edema. Rats (250 g) were gavaged with EtOH to achieve a blood EtOH level in the range of 100 mg/dL prior to burn or sham injury (25% total body surface area). A group of rats was treated with Ac-YVAD-CHO (5 mg/kg), an inhibitor of caspase-1 (an enzyme that converts pro-IL-18, an inactive form of IL-18, to mature IL-18), at the time of injury. One day after injury, rats were killed. IL-18 production was determined in circulation and in the supernatants harvested from spleen, mesenteric lymph nodes, and Peyer's patch cell cultures as well as in intestinal tissue homogenates. Neutrophil accumulation in intestine was determined by measuring myeloperoxidase (MPO) activity. We found a significant increase in IL-18 levels in the lymphoid cell supernatants and intestinal tissue homogenates obtained from EtOH and burn-injured rats compared with the rats receiving burn or sham injury. This was accompanied by an increase in intestinal MPO and edema. No demonstrable change in intestinal morphology was observed in any group. Treatment of rats with caspase-1 inhibitor significantly attenuated the increase in IL-18 levels and intestinal MPO activity in EtOH and burn-injured rats. Inhibition of IL-18 also prevented an increase in intestinal tissue water content. As MPO is considered an index of neutrophil infiltration, results presented in this manuscript collectively suggest that IL-18 up-regulation is likely to contribute to the increased neutrophil infiltration and edema in intestinal tissue observed following EtOH and burn injury.

Corticosterone suppresses mesenteric lymph node T cells by inhibiting p38/ERK pathway and promotes bacterial translocation after alcohol and burn injury

Previous studies showed that alcohol (EtOH) intoxication before burn injury suppresses mesenteric lymph node (MLN) T cell functions and increases gut bacterial translocation. In this study, we examined whether corticosterone (Cort) plays any role in suppressing MLN T cell function and bacterial accumulation after EtOH intoxication and burn injury. Rats were gavaged with EtOH to achieve a blood EtOH level of approximately 100 mg/dl before receiving 25% total body surface area burn or sham injury. A group of rats was treated with the Cort synthesis inhibitor metyrapone (25 mg/kg) at the time of injury and on day 1 after injury. Two days after injury, a significant increase in blood Cort levels and suppression of MLN T cell proliferation and IL-2 production was observed in rats receiving combined insult of EtOH intoxication and burn injury compared with rats receiving EtOH intoxication or burn injury alone. There was no change in T cell apoptosis after combined insult of EtOH and burn injury. Furthermore, T cell suppression was accompanied by a significant decrease in p38 and ERK1/2 activation (phosphorylation). There was no difference in JNK activation after EtOH and burn injury. Treatment of rats with metyrapone prevented the suppression of MLN T cell proliferation, IL-2 production, and p38 and ERK1/2 phosphorylation. Restoration of T cell function in metyrapone-treated animals was also associated with the decrease in bacterial accumulation in MLN. These findings suggest that EtOH intoxication before burn injury augments Cort release, which suppresses MLN T cell function by inhibiting p38 and ERK1/2 activation and promotes bacterial accumulation in MLN after EtOH and burn injury.

Effect of acute alcohol ingestion prior to burn injury on intestinal bacterial growth and barrier function

Previous studies from our laboratory have shown that acute alcohol (EtOH) ingestion prior to burn injury enhances intestinal bacterial translocation. This study tested if increased intestinal bacterial translocation in alcohol and burn injured rats is due to an overgrowth in intestinal bacteria. We determined if the translocation was accompanied with alterations in intestinal permeability and immune cell population. Rats (225-250 g) were gavaged with alcohol to achieve a blood EtOH level in the range of 100 mg/dl prior to burn or sham injury (25% total body surface area). Two days after injury, we found that acute alcohol ingestions prior to burn injury results in a significant increase in bacterial counts in small intestine. The increase in intestinal bacterial counts accompanied a significant increase in intestinal permeability. Finally, immunohistochemical analysis revealed a substantial (p<0.05) loss of both T cell and dendritic cells in intestine of alcohol and burn injured rats compared with intestine of rats receiving either burn or sham injury. Altogether, results presented in this manuscript suggest that increase in intestinal bacterial growth along with alterations in intestinal permeability and immune status contribute to the increase in bacterial translocation observed in alcohol and burn injured rats.

Alcohol ingestion before burn injury decreases splanchnic blood flow and oxygen delivery

Recent studies from our laboratory have shown that alcohol and burn injury impair intestinal barrier and immune functions. Although multiple factors can contribute to impaired intestinal barrier function, such an alteration could result from a decrease in intestinal blood flow (BF) and oxygen delivery (DO2). Therefore, in this study, we tested the hypothesis that alcohol ingestion before burn injury reduces splanchnic blood flow and oxygen delivery. Rats (250 g) were gavaged with alcohol to achieve a blood ethanol level in the range of 100 mg/dl before burn or sham injury (25% total body surface area). Day 1 after injury, animals were anesthetized with methoxyflurane. Blood pressure, cardiac output (CO), +/-dP/dt, organ BF (in ml.min(-1).100 g(-1)), and DO2 (in mg.ml(-1).100 g(-1)) were determined. CO and organ BF were determined using a radioactive microsphere technique. Our results indicate that blood pressure, CO, and +dP/dt were decreased in rats receiving a combined insult of alcohol and burn injury compared with rats receiving either burn injury or alcohol alone. This is accompanied by a decrease in BF and DO2 to the liver and intestine. No significant change in BF to the coronary arteries (heart), brain, lung, skin, and muscles was observed after alcohol and burn injury. In conclusion, the results presented here suggest that alcohol ingestion before burn injury reduces splanchnic BF and DO2. Such decreases in BF and DO2 may cause hypoxic insult to the intestine and liver. Although a hypoxic insult to the liver would result in a release of proinflammatory mediators, a similar insult to the intestine will likely perturb both intestinal immune cell and barrier functions, as observed in our previous study.

Combined alcohol and burn injury differentially regulate p-38 and ERK activation in mesenteric lymph node T cell

Recent studies from our laboratory have suggested that acute alcohol ingestion prior to burn injury enhances gut bacterial translocation by suppressing T cell-mediated intestinal immune defense. To determine the mechanism responsible for suppressed T cell function, we examined the activation of mitogen-activated protein kinases (MAPK) members p-38 and ERK-1/2. Both p-38 and ERK-1/2 are known to play a significant role in the T cell proliferation and their cytokine production. Rats were gavaged with ethanol to achieve a blood alcohol level of approximately 100 mg/dl, before they were subjected to a 25% total body surface area burn injury. Two days after injury, rats were sacrificed and mesenteric lymph node (MLN) T cells were isolated and their ability to proliferate in response to anti-CD3 was determined. For p-38 and ERK-1/2 determination, T cells were divided into two groups. Cells in one group were stimulated with anti-CD3 for 3 min and lysed. The cells in the second group were cultured for approximately 18 h in the presence of anti-CD3 and lysed. MAPK status in 18-h cultured cells allowed us to determine whether or not the changes in p-38 and ERK-1/2 are transient or persist in the proliferating cells. Two days after injury, anti-CD3-mediated MLN T cell proliferation was more suppressed in rats gavaged with alcohol prior to burn injury compared to rats receiving either burn injury alone or sham-injured rats regardless of their exposure. Western blot analyses showed significant inhibition of ERK-1/2 phosphorylation in both freshly isolated and 18-h cultured T cells from alcohol and burn-injured rats compared to the sham rat T cells. The inhibition of p-38 phosphorylation in T cells derived from alcohol and burn-injured rats was found to be transient as no significant difference in p-38 phosphorylation was noted between the 18 h incubated MLN T cells of sham and alcohol and burn-injured rats. Taken together, our findings suggest that low levels of ERK-1/2 activation is likely to play a significant role in MLN T cell proliferative suppression in alcohol and burn-injured rats.

Alteration of intestinal intraepithelial lymphocytes and increased bacterial translocation in a murine model of cirrhosis

Alterations in immunological defense in the gut may lead to the bacterial infection that is frequently associated with cirrhosis of the liver. The aim of this study was to investigate the changes in distribution and function of intestinal intraepithelial lymphocytes (IELs) in relation to intestinal barrier dysfunction in experimental cirrhosis. Cirrhosis was induced in mice by treatment with carbon tetrachloride (CCl4) intraperitoneally with 5% alcohol in drinking water for 12 weeks. Bacterial translocation was assessed in mesenteric lymph nodes (MLNs) by the transport of fluorescence-labeled latex beads and by bacteriological cultures. The lymphocyte subpopulation was compared in three groups (cirrhosis, alcohol alone and controls). IFN-gamma production from isolated IELs was determined by ELISA after stimulation with anti-CD3 or IL-12/IL-18. The total number of IELs significantly increased in the cirrhosis and alcohol groups. There was a preferential increase in TCRgammadelta+CD8+ population in the alcohol group, but no change in cirrhosis. Bacterial translocation was negative in the control group, and a small number was noted in the alcohol group, whereas it was significantly noted in the cirrhosis group. Although the number of IEL was significantly increased in the cirrhosis group, their proliferative response was decreased, and IFN-gamma production from each IEL was markedly diminished in either stimulation by anti-CD3 or IL-12/IL-18. These changes were more remarkable in the cirrhosis group than in the alcohol group. In conclusion, bacterial translocation due to intestinal barrier dysfunction in cirrhosis may be closely correlated with the alteration of the immune function in IELs.

Ethanol and burn injury: estrogen modulation of immunity

A good deal of clinical evidence supports the idea that ethanol exposure is a causative factor in the occurrence of burn or other traumatic injury. In addition, more recent evidence reveals that individuals who sustain injury while under the influence of ethanol suffer from increased morbidity and mortality compared with those with comparable injuries who did not consume ethanol. Many of the complications seen in ethanol-exposed, burn-injured subjects result from depressed immune responses, which render the host unable to fight off infectious organisms. Both injury and ethanol exposure independently affect cellular immune responses, including delayed-type hypersensitivity and splenocyte proliferative responses, and the combined insult of ethanol exposure and injury acts in conjunction to increase further the magnitude and duration of immunosuppression. It is interesting that these immune responses can be restored experimentally in male, but not in female, mice by administration of low, proestrous levels of estrogen. The complexity of the responses after injury in ethanol-exposed subjects is multiplied when the sex of the subjects is added to the equation. This is due, in part, to the effect of the combined insult of injury and ethanol on the production of gonadal steroid hormones in males and females and the direct effects of those hormones on cytokine gene expression in sensitive cell types such as the macrophage. Evidence seems to indicate that cellular immune responses after ethanol exposure and burn injury differ in kinetics and magnitude for male and female subjects, and, hence, the therapeutic interventions to treat burn-injured patients should take into account both sex and ethanol exposure.

Impaired intestinal immunity and barrier function: a cause for enhanced bacterial translocation in alcohol intoxication and burn injury

Alcohol intoxication is being recognized increasingly as the major factor in pathogenesis after burn injury. Findings from multiple studies support the suggestion that, in comparison with burn-injured patients who sustained injury in the absence of alcohol intoxication, burn-injured patients who sustained injury under the influence of alcohol exhibit higher rates of infection and are more likely to die. Thus, infection becomes the primary cause of death in burn-injured patients. Because the intestine is considered to be a major source of bacteria, studies in experimental animals have been designed to examine whether alcohol intoxication before burn injury enhances bacterial translocation from the intestine. Results of these studies have shown a several-fold increase in bacterial translocation from the intestine in the group of animals receiving combined insult of alcohol intoxication and burn injury compared with findings for the groups receiving either insult alone. Alcohol intoxication and burn injury independent of each other have also been shown to cause an increase in bacterial translocation. The gastrointestinal tract normally maintains a physical mucosal and immunologic barrier that provides an effective defense in keeping bacteria within the intestinal lumen. However, in injury conditions these defense mechanisms are impaired. Intestinal bacteria consequently gain access to extraintestinal sites. Intestine-derived bacteria are implicated in causing systemic infection and in subsequent multiple organ dysfunction in both immunocompromised patients and patients with injury, such as burn and trauma. In this article, we discuss three potential mechanisms that are likely to contribute to the increase in bacterial translocation in alcohol intoxication and burn injury: (1) increase in bacterial growth in the intestine, (2) physical disruption of mucosal barrier of the intestine, and (3) suppression of the immune defense in the intestine.

Ethyl pyruvate ameliorates acute alcohol-induced liver injury and inflammation in mice

Ethyl pyruvate dissolved in a calcium-containing balanced salt solution--Ringer's ethyl pyruvate solution (REPS)--ameliorates ileal mucosal hyperpermeability and decreases the expression of several proinflammatory genes when it is used instead of Ringer's lactate solution (RLS) to resuscitate mice from hemorrhagic shock. Herein, we sought to determine whether delayed treatment with REPS would be beneficial in a murine model of acute alcoholic liver injury associated with binge drinking. Mice were gavaged with 3 doses of ethanol (5 g/kg each dose) over a 12-hour period and then randomized to treatment with 3 intraperitoneal doses of REPS or RLS over 12 hours. Compared with sham-treated controls not subjected to alcohol intoxication, RLS-treated mice demonstrated histologic evidence of fatty change and piecemeal necrosis of hepatocytes in the liver, as well as a significant increase in the plasma concentration of alanine aminotransferase. Biochemical changes induced by alcohol administration included increased hepatic lipid peroxidation, nuclear factor-kappaB activation, and tumor necrosis factor-alpha messenger RNA expression. All of these alcohol-induced effects were ameliorated by treatment with REPS instead of RLS. These data support the view that treatment with REPS ameliorates the hepatic inflammatory response and decreases hepatocellular injury in mice subjected to acute alcohol intoxication.

Effect of acute ethanol exposure on the dermal inflammatory response after burn injury

BACKGROUND

More than 100,000 people each year are admitted to U.S. hospitals for severe burn injury. Strikingly, ethanol use prior to injury is apparent in nearly 50% of burn patients, rendering them six times more likely to die from infection than patients not exposed to ethanol. We previously reported that the kinetics and magnitude of neutrophil chemokine production and subsequent accumulation of neutrophils in the lung was dramatically altered when ethanol exposure preceded injury. Here, we tested whether burn injury and ethanol exposure combined, altered susceptibility to infection, neutrophil chemoattractant production, and neutrophil accumulation at the site of the burn wound.

METHODS

Male B(6)D(2)F1 mice were administered a dose of ethanol designed to achieve 90-100 mg/dl circulating levels and 30 min later subjected to a 15% total body surface area dorsal scald injury. Susceptibility to topically applied Pseudomonas aeruginosa was examined. At various times after injury, burn wound and normal tissues were collected for assessments of neutrophil counts, myeloperoxidase quantitation, and neutrophil chemoattractant (KC and MIP-2) production.

RESULTS

Ethanol exposure prior to burn injury enhanced susceptibility to infection after burn and was associated with significantly elevated production of KC, but not MIP-2, at the wound site. Despite the enhanced elevation of KC, neutrophil accumulation in the wounds of ethanol exposed, burn injured mice did not differ from those that received burn injury alone. TNFalpha (a potent activator of neutrophils), however, was found to be significantly elevated in the wounds of mice that received only burn injury, but not in those that received injury in combination with prior ethanol exposure.

CONCLUSION

In the presence of ethanol, neutrophils are adequately recruited to the site of burn injury, but their host defense functions are impaired, perhaps due to the lack of proinflammatory cytokines such as TNFalpha.

Effects of ethanol on gut-associated lymphoid tissues in a model of bacterial translocation: a possible role of apoptosis

Chronic ethanol intake has been shown to be associated with immune suppression and impairment of epithelial barrier function. We investigated the effects of ethanol on intestinal immunity and its relation to bacterial translocation (BT). Male Wistar rats were assigned to one of three groups and received respective diets for 28 days. The ethanol-fed group [(EG); n=11] received a liquid diet containing 5% [volume/volume (vol./vol.)] ethanol; a pair-fed group [(PFG); n=11] received an isocaloric diet without ethanol; and a third (control) group [(CG); n=11] received water and chow ad libitum. On experimental day 29, animals in the EG and the PFG underwent distal ileum ligature and small intestine inoculation of a tetracycline-resistant Escherichia coli strain (TcR E. coli R6), by means of gastric intubation, followed by duodenal ligature. One hour after inoculation, mesenteric lymph nodes, right lobe of liver, spleen, and left kidney were excised for bacterial studies. Sections of jejunum and colon were immunostained, with the use of antibodies against immunoglobulin (Ig) A, T cells, macrophages, and proliferating cell nuclear antigen (PCNA). Apoptosis was determined by the terminal deoxynucleotidyltransferase TdT-mediated dUDP-biotin nick end labeling (TUNEL) method. Bacterial translocation rates were greater in the PFG compared with findings for the EG. Lamina propria of the jejunum of the EG showed a reduction in the densities of IgA+ cells and T cells compared with findings for the PFG and the CG. Colonic lamina propria of the EG showed reduced densities of IgA+ cells and macrophages compared with findings for the PFG and the CG. Apoptotic index was increased in the EG compared with findings for the PFG and the CG, in both jejunum and colon. Proliferation index was not significantly different among groups. Results of the current study show that chronic ethanol ingestion led to a reduction of cellular and humoral components of the intestinal mucosa, possibly by cell loss as a result of ethanol-induced apoptosis. The reduced rates of BT observed after chronic ethanol intake seem to indicate that factors irrespective of immune function might be involved in BT inhibition.

Alcohol, injury, and cellular immunity

It is widely accepted that alcohol exposure is a causative factor in the occurrence of burn or other traumatic injury. It is less well known that individuals who have consumed alcohol before sustaining an injury suffer from increased morbidity and mortality compared with the morbidity and mortality of non-alcohol-consuming subjects with similar injuries. Complications due to bacterial infection are the most common burn sequelae in injured patients and are frequently associated with depressed immunity. Independently, alcohol exposure and injury have been shown to influence cellular immunity negatively. These changes in immunity are closely linked to injury- or alcohol-induced alterations in the cytokine milieu in both clinical studies and animal models. Not surprisingly, the combination of insult of alcohol exposure and burn injury results in immune suppression that is greater in magnitude and duration compared with either insult alone. The combined effects of alcohol and injury on immunity have been examined in a limited number of studies. However, results of these studies support the suggestion that altered cytokine production is an integral part of the immune dysregulation and increased mortality that is observed. In particular, the increased presence of macrophage-derived mediators observed after burn or alcohol exposure alone seems to be synergistically increased in a combined injury model. Although more research is needed, it is likely that therapeutic modalities that include manipulation of cytokine networks to boost cellular immunity may improve outcome for patients who sustain injuries subsequent to consuming alcohol.

Gut-associated lymphoid T cell suppression enhances bacterial translocation in alcohol and burn injury

The mechanism of alcohol-mediated increased infection in burn patients remains unknown. With the use of a rat model of acute alcohol and burn injury, the present study ascertained whether acute alcohol exposure before thermal injury enhances gut bacterial translocation. On day 2 postinjury, we found a severalfold increase in gut bacterial translocation in rats receiving both alcohol and burn injury compared with the animals receiving either injury alone. Whereas there were no demonstrable changes in intestinal morphology in any group of animals, a significant increase in intestinal permeability was observed in ethanol- and burn-injured rats compared with the rats receiving either injury alone. We further examined the role of intestinal immune defense by determining the gut-associated lymphoid (Peyer's patches and mesenteric lymph nodes) T cell effector responses 2 days after alcohol and burn injury. Although there was a decrease in the proliferation and interferon-gamma by gut lymphoid T cells after burn injury alone; the suppression was maximum in the group of rats receiving both alcohol and burn injuries. Furthermore, the depletion of CD3(+) cells in healthy rats resulted in bacterial accumulation in mesenteric lymph nodes; such CD3(+) cell depletion in alcohol- and burn-injured rats furthered the spread of bacteria to spleen and circulation. In conclusion, our data suggest that the increased intestinal permeability and a suppression of intestinal immune defense in rats receiving alcohol and burn injury may cause an increase in bacterial translocation and their spread to extraintestinal sites.

Cellular immunity after ethanol exposure and burn injury: dose and time dependence

Acute ethanol exposure prior to burn injury increases the immune dysfunction seen with burn alone, which has been partially attributed to increased circulating and splenic macrophage production of interleukin-6 (IL-6). The current studies examined the effect dose and timing of ethanol exposure prior to burn on cellular immunity. Mice with high (300 mg/dl) circulating levels of ethanol at the time of burn demonstrated further suppression of the delayed type hypersensitivity (DTH) and splenocyte proliferative responses in comparison to mice with moderate (100 mg/dl) ethanol levels. Interestingly, the increase in macrophage IL-6 secretion seen at the moderate dose was not augmented at the high dose; however, the circulating IL-6 levels did reveal a further increase at the high ethanol dose. There were no alterations in splenocyte subset populations and/or apoptosis at the moderate vs. the high ethanol dose. Moderate ethanol exposure 24 h, in comparison to 30 min, before injury resulted in similar decreases in the DTH. These results suggest that the dose-dependent effects of ethanol on immunity following burn injury are not the result of splenic macrophage IL-6 production as shown at the moderate dose and that the immune suppressive effects of ethanol in this model persist after it is cleared from the circulation.

Ethanol exacerbates T cell dysfunction after thermal injury

To understand the mechanism of suppressed immunity following alcohol consumption and thermal injury, we analyzed T cell functions in a mouse model of acute alcohol exposure and burn injury. Mice with blood alcohol levels at approximately 100 mg/dl were given a 15% scald or sham injury. Mice were sacrificed 48 h after injury. Our data demonstrated a 20-25% decrease in Con A-mediated splenic T cell proliferation (p<0.01) and 45-50% decrease in interleukin-2 (IL-2) production (p<0.01) following burn injury compared to the T cells from sham animals. A further decrease in the proliferation (25-30%) and IL-2 production (40-45%) was detected in T cells derived from burned animals receiving alcohol as compared to burn alone. No significant change in the proliferation and IL-2 production was observed in splenic T cells derived from sham-injured mice regardless of alcohol exposure. Additionally, there was no demonstrable difference in splenocyte apoptosis in any treatment group. These results suggest that alcohol consumption prior to burn injury causes a greater decrease in T cell proliferation and IL-2 production compared to either burn or alcohol injury alone that may further attenuate the cell-mediated immunity and thus enhance susceptibility to infection.

Elevation in pulmonary neutrophils and prolonged production of pulmonary macrophage inflammatory protein-2 after burn injury with prior alcohol exposure

Various studies have shown that alcohol exposure before thermal injury leads to increased morbidity and mortality. Pulmonary failure is a major complication seen in these patients. This study examines the effects of prior alcohol exposure on lung pathology after burn injury. There is a marked increase in neutrophil recruitment in the lung after thermal injury, and herein we show that this appears to be significantly elevated in animals given alcohol before burn injury. Consequently, we chose to determine whether there is a difference in pulmonary production of macrophage inflammatory protein (MIP)-2, a potent neutrophil chemoattractant, in mice subjected to a 15% total body surface area scald (or sham) injury with or without prior ethanol treatment. Lung tissue was obtained at various time points after injury and homogenates were assayed for MIP-2 by enzyme-linked immunosorbent assay. At 2 h after injury, peak levels of the chemokine were produced in both burn and burn + alcohol-treated mice. This represents a 7-fold increase above baseline. In mice exposed to burn injury alone, the level of MIP-2 returned to baseline within 8 h. In contrast, mice given alcohol before burn injury continued to show elevated levels of the chemokine at 8 h, after which MIP-2 decreased. This study may provide a basis for understanding the mechanism responsible for the increased neutrophil presence in the lung after thermal injury in individuals who have consumed alcohol. Subsequently, this may lead to the enhanced neutrophil-mediated pulmonary damage observed in these patients.

Femur fracture induces site-specific changes in T-cell immunity

BACKGROUND

Trauma is associated with altered host defense and susceptibility to infection, in part due to cytokine dysregulation and altered T-cell immunity. The gut-associated lymphoid tissue (GALT) provides a defense against infection and contributes to the process of mucosal healing by T-cell activation and cytokine production.

OBJECTIVE

To determine whether femur fracture induces alterations in Peyer's patch and splenic T-cell phenotype, proliferative response, and cytokine expression following traumatic injury.

METHODS

Mice underwent femur fracture or sham procedure and, 48 h later, lymphocytes were isolated from spleen and Peyer's patches. Lymphocytes were cultured, and lipopolysaccharide (10 microg/ml) was added in some cultures. Cells and supernatant were harvested at 48 h. Proliferation was analyzed by [3H]thymidine, and interleukin-10 (IL-10) protein was measured by ELISA in the culture supernatant. T-cell phenotype was determined by flow cytometry.

RESULTS

Femur fracture induced a significant increase in proliferative response in Peyer's patch immunocytes. In contrast, no significant differences were identified in splenocyte proliferative response 48 h after femur fracture injury. Femur fracture induced a significant decrease in IL-10 protein expression of both splenocytes and Peyer's patches. Femur fracture also induced a significant increase in the fraction of CD3(+), CD4(+), and T-cell receptor-alpha beta Peyer's patch immunocytes, whereas splenocytes demonstrated no significant phenotypic change.

CONCLUSION

Femur fracture is associated with significant alterations in Peyer's patch but not splenic T-cell phenotype and proliferative response early (48 h) after injury. Changes in the GALT immune response may contribute to intestinal mucosal dysfunction and increased susceptibility to gut-derived sepsis after traumatic injury.

Effect of alcohol on bacterial translocation in rats

Bacterial translocation has been proposed to be important in the pathophysiology of sepsis, as well as to be a consequence of sepsis. To study the effect of alcohol on bacterial translocation from the gut, normal Sprague-Dawley rats were administered alcohol by gavage by two regimens: Acute (3.7 g/kg, one dose) or Subacute (1 of 2 doses, 2.4 or 3.7 g/kg/day once daily for 14 days). Mesenteric lymph node cultures were performed, and portal venous blood was assayed for endotoxin. Ileal and cecal permeability studies were performed in the Acute and Subacute groups using fluorescein isothiocyanate-labeled dextrans of either 4,000 or 70,000 kDa size. As an index of the effect of systemic endotoxin, tissues from mesenteric lymph nodes, liver, and intestinal Peyer's patches were assayed for the presence of mRNA for tumor necrosis factor. Additionally, because extrapulmonary sepsis has been shown to suppress pulmonary antibacterial defenses, animals in the Subacute group were challenged by aerosol inoculation with Pseudomonas aeruginosa to determine bacterial clearance and alveolar cellular responses. The results show that neither of the alcohol regimens resulted in bacterial growth from mesenteric lymph nodes or portal blood. Animals in the Subacute group had more endotoxin present in portal blood than did the Control group (92.9 pg/ml vs. 40.2 pg/ml; p < 0.02). None of the animals had demonstrable mRNA for tumor necrosis factor in any of the tissues assayed. There were no demonstrable increases in ileal or cecal permeability for either the small or large molecular weight dextran in either alcohol group. Furthermore, there was no delay in the clearance of P. aeruginosa from the lung in the Subacute group, but these animals recruited fewer neutrophils into the airspaces in response to this challenge than did the Control animals. Thus, alcohol intoxication does not result in bacterial translocation from the gut in this model. Despite higher levels of portal venous endotoxin in the animals in the Subacute alcohol group, no adverse systemic consequences of this phenomenon could be demonstrated.

The urinary ratio of 5-hydroxytryptophol to 5-hydroxyindole-3-acetic acid in surgical patients with chronic alcohol misuse

The urinary ratio of 5-hydroxytryptophol to 5-hydroxyindole-3-acetic acid was reported to be elevated for a period of up to 22 h following acute alcohol ingestion. Therefore, the ratio could detect continuous alcohol consumption, in what was considered to be a high-risk surgical group, on the evening prior to surgery. The aim of this study was to determine the preoperative ratio of 5-hydroxytryptophol to 5-hydroxyindole-3-acetic acid in patients with continuous preoperative alcohol misuse. Forty-two patients participated in this institutionally approved study, once their written informed consent had been obtained. Chronic alcoholics were defined by meeting the criteria of the Diagnostic and Statistical Manual of Mental Disorders criteria and an ethanol consumption > or =60 g/day. The urine samples were taken preoperatively and determined by means of gas chromatography-mass spectrometry and high performance liquid chromatography. The urinary ratio of 5-hydroxytryptophol to 5-hydroxyindole-3-acetic acid was significantly increased in chronic alcoholics. The ICU stay of these patients was significantly prolonged due to an increased incidence of pneumonia and sepsis. Five chronic alcoholics died, whereas no deaths occurred in the nonalcoholic group (p = 0.05). As the measurement of the urinary ratio of 5-hydroxy-tryptophol to 5-hydroxyindole-3-acetic acid could detect alcohol consumption immediately prior to operation, this marker could assist the carbohydrate-deficient transferrin in screening for patients with high-level dependency; these patients were considered to be at a high risk of developing intercurrent complications.

Hepatic haemodynamics and reticuloendothelial function in the rat in response to chronic ethanol administration

This study investigated the effects of chronic ethanol intake on hepatic haemodynamics and reticuloendothelial system function in the rat. Comparisons were also made with blood flow to pancreas, kidney, spleen, lung and skin. Male Wistar rats, approximately 0.15 kg initial body weight, were fed a diet containing 35% of the total calories as ethanol. Controls were pair-fed identical amounts of the same diet in which ethanol was replaced by isocaloric glucose. The hepatic perfusion index and reticuloendothelial function was determined with [(99m) Tc]-labelled sulphur colloid [(99m) Tc]-SC) and blood flow with radiolabelled microspheres under anaesthesia. After 4-5 weeks the weights of liver and skin of alcohol fed rats decreased by 10% (p= 0.040) and 23% (p= 0.024), respectively, compared to controls and there was a small increase in kidney weight (15%, p = 0.001). Blood flow to liver, pancreas, kidney, spleen, lung and skin was not altered significantly by chronic alcohol administration, irrespective of whether the data were expressed as a percentage of cardiac output, blood flow per minute per organ or blood flow per minute per g tissue weight (p > 0.113 in all instances). However, there was a significant increase in splenic reticuloendothelial system activity (+ 121%, p = 0.018). Hepatic reticuloendothelial system activity was also increased (+ 22%, p = 0.061). Chronic alcohol administration resulted in significant increases in portal pressure (+ 55%, p = 0.042) and portal venous resistance (+ 66%, p = 0.001), but portal venous inflow and hepatic perfusion index were not altered compared to controls The results of this study indicated that chronic alcohol administration did not alter visceral blood flow significantly, but did increase portal pressure, portal vascular resistance and reticuloendothelial system activity.

Effect of running intensity on intestinal permeability

Enhanced intestinal permeability has been associated with gastrointestinal disorders in long-distance runners. The primary purpose of this study was to evaluate the effect of running intensity on small intestinal permeability by using the lactulose and rhamnose differential urinary excretion test. Secondary purposes included assessing the relationship between small intestinal permeability and gastrointestinal symptoms and evaluating gastric damage by using sucrose as a probe. Six healthy volunteers [5 men, 1 woman; age = 30 +/- 2 yr; peak O2 uptake (VO2peak) = 57.7 +/- 2.1 ml.kg-1.min-1] rested or performed treadmill exercise at 40, 60, or 80% VO2peak for 60 min in a moderate environment (22 degrees C, 50% relative humidity). At 30 min into rest or exercise, the permeability test solution (5 g sucrose, 5 g lactulose, 2 g rhamnose in 50 ml water, approximately 800 mosM) was ingested. Urinary excretion rates (6 h) of the lactulose-to-rhamnose ratio were used to assess small intestinal permeability, and concentrations of each probe were determined by using high-performance liquid chromatography. Running at 80% VO2peak increased (P < 0.05) small intestinal permeability compared with rest, 40, and 60% VO2peak with mean values expressed as percent recovery of ingested dose of 0.107 +/- 0.021 (SE), 0.048 +/- 0.009, 0.056 +/- 0.005, and 0.064 +/- 0.010%, respectively. Increases in small intestinal permeability did not result in a higher prevalence of gastrointestinal symptoms, and urinary recovery of sucrose did not reflect increased gastric permeability. The significance and mechanisms involved in increased small intestinal permeability after high-intensity running merit further investigation.

Actions of acute ethanol intoxication on cardiopulmonary function after an endotoxin challenge

BACKGROUND

This study examined whether acute ethanol (EtOH) intoxication could alter the systemic inflammatory response evoked by endotoxin (lipopolysaccharide, LPS).

METHODS

Anesthetized (fentanyl) and mechanically ventilated mongrel pigs were administered 20% EtOH (3 gm/kg) or its vehicle (VEH) by means of gastric lavage. After 60 minutes of equilibration, blood levels were 110 to 130 mg/dl, and LPS (1 microgram/kg per 30 minutes) was infused intravenously to mimic the type of sepsis that might be encountered after a penetrating abdominal injury.

RESULTS

LPS caused initial pulmonary vasoconstriction followed by cardiovascular collapse in 7 of 14 pigs with EtOH versus 0 of 14 pigs with VEH (p = 0.0058); survival time averaged 2.4 +/- 0.5 hours for EtOH versus 4.5 +/- 0.3 hours for VEH (p = 0.002). At 3 to 5 hours after LPS infusion the survivors were acidotic (base excess, -5.1 +/- 1.5 versus 0.4 +/- 1.1 mEq/L; p = 0.007) and vasodilated (systemic vascular resistance, 54% +/- 9% versus 111% +/- 9% baseline; p = 0.005). Systemic arterial pressure and cardiac filling pressures were maintained with fluid resuscitation, but more was required for EtOH versus VEH (80 +/- 11 versus 42 +/- 5 ml/kg/hr; p = 0.0034). A diffuse capillary leak was detected with gamma scintigraphy and regional uptake of technetium 99m albumin. With EtOH versus VEH microvascular permeability was higher in abdomen (p = 0.01) and liver (p = 0.06) but not in lung (p = 0.29). These changes were probably mediated in part by leukosequestration: neutrophil counts were initially reduced more than 80% in both groups, but they then rebounded with VEH (p < 0.05) but not EtOH. The early versus late deaths within the EtOH group were distinguished by higher baseline levels of cortisol (1.4 +/- 0.3 versus 0.9 +/- 0.2 micrograms/dl; p = 0.075) and by a 50% decrease evoked by EtOH (p = 0.0042) versus no change in the late death subgroup. After LPS infusion cortisol peaked sooner and then recovered with VEH (p < 0.05), whereas the peak occurred later and there was no decay with EtOH. In addition, at 60 and 90 minutes after LPS infusion tumor necrosis factor was 119 +/- 27 and 240 +/- 40 pg/ml with VEH versus 62 +/- 15 and 95 +/- 23 pg/ml with EtOH (p = 0.041 and p = 0.0030).

CONCLUSIONS

By means of a leukocyte-mediated mechanism in the splanchnic circulation, acute EtOH impaired host defense, which exacerbated LPS-evoked systemic inflammatory response. In context with our earlier experimental study and two large clinical trials, it appears that acute EtOH can have opposite effects on the vulnerability to posttrauma sepsis, depending on the timing of the septic insult and on the immune status at the time of septic challenge.