The role of chronic alcohol abuse in the development of acute respiratory distress syndrome in adults

Acute alcohol inhibits TNF-alpha processing in human monocytes by inhibiting TNF/TNF-alpha-converting enzyme interactions in the cell membrane

Alcohol abuse has long been known to adversely affect innate immune responses and predispose to infections. One cellular mechanism responsible for this effect is alcohol-induced suppression of TNF-alpha by mononuclear phagocytes. We undertook experiments to better understand the cellular mechanisms by which alcohol dose-dependently suppresses TNF elaboration by human monocytes. Here we show in human primary monocytes and cell lines that alcohol suppresses LPS-induced TNF secretion post-transcriptionally by inhibiting cellular processing by TNF-alpha-converting enzyme (TACE). Using fluorescent resonance energy transfer microscopy, physiological relevant levels of alcohol resulted in a reversible dose-dependent decrease in fluorescent resonance energy transfer efficiency between TNF and TACE. These data demonstrate that alcohol inhibits interactions between TNF and its converting enzyme, TACE, possibly by affecting membrane fluidity. These data in part explain the cellular mechanisms by which alcohol impairs monocyte function and may identify immunotherapeutic targets aimed at restoring immune function in this at-risk patient population.

Chronic alcohol abuse is associated with an increased incidence of acute respiratory distress syndrome and severity of multiple organ dysfunction in patients with septic shock

OBJECTIVE

Alcohol is one of the most commonly used drugs in the world and causes dysfunction in many vital organs. However, the effects of chronic alcohol abuse on acute lung injury and nonpulmonary organ dysfunction are relatively unexplored. The goal of this study was to determine the effects of chronic alcohol abuse on the incidence and severity of the acute respiratory distress syndrome and multiple organ dysfunction syndrome in patients with septic shock.

DESIGN

Multicenter prospective epidemiologic study.

SETTING

Intensive care units of four university urban hospitals. PATIENTS A total of 220 critically ill patients with septic shock.

MEASUREMENTS AND MAIN FINDINGS

Thirty percent of the patients (66 of 220) were identified as having a history of chronic alcohol abuse based on a positive response to an alcohol screening questionnaire. The incidence of acute respiratory distress syndrome in patients with a positive history of chronic alcohol abuse was 70% (46 of 66), compared with 31% (47 of 154) in individuals without a history of chronic alcohol abuse (p < .001). After adjusting for differences in the source of infection, sex, age, chronic hepatic dysfunction, diabetes, severity of illness, nutritional status, and smoking status, the effects of chronic alcohol abuse on the incidence of acute respiratory distress syndrome remained significant (p < .001; odds ratio, 3.70; 95% confidence interval, 1.83-7.71). The effect of the source of infection (pulmonary vs. nonpulmonary) on the development of acute respiratory distress syndrome also remained significant in this multivariable analysis (p < .001; odds ratio, 3.68; 95% confidence interval, 1.95-7.18). Based on the highest daily Sequential Organ Failure Assessment score, patients with a history of chronic alcohol abuse had more severe nonpulmonary organ dysfunction when compared with nonalcoholics (9.42 +/- 3.89 vs. 8.05 +/- 4.10, p = .01). After adjusting for source of infection, sex, age, nutritional status, history of diabetes, and smoking status, the effects of chronic alcohol abuse on the incidence of nonpulmonary organ dysfunction also remained significant (p = .03; odds ratio, 2.07; 95% confidence interval, 1.09-3.97).

CONCLUSIONS

We conclude that chronic alcohol abuse is an independent risk factor for acute respiratory distress syndrome and increases the severity of nonpulmonary organ dysfunction in patients with septic shock.

Chronic ethanol ingestion increases susceptibility to acute lung injury: role of oxidative stress and tissue remodeling

Clinical studies have demonstrated that chronic alcohol abuse is an independent outcome variable in acute lung injury. The Emory Center for the Study of Acute Lung Injury is determining the mechanisms by which ethanol increases susceptibility to acute lung injury. We developed a rat model of chronic ethanol ingestion and demonstrated that ethanol predisposes rats to edematous lung injury elicited by endotoxemia or sepsis. Chronic ethanol ingestion in rats led to decreased levels of glutathione, an important antioxidant in the lung, and this defect was associated with alterations in epithelial cell permeability, decreased alveolar liquid clearance, decreased cell viability, and decreased surfactant production. Chronic ethanol ingestion also led to the activation of lung tissue remodeling as demonstrated by the increased expression of profibrotic growth factors, matrix components, and metalloproteases. In cultured fibroblasts, the induction of the matrix glycoprotein fibronectin by ethanol was mediated via nicotinic acetylcholine receptor-dependent signal transduction. We speculate that these alterations render the host susceptible to acute lung injury by diminishing the protective mechanisms of the lung and promoting exaggerated inflammatory and tissue repair responses elicited against injurious agents.

Ethanol impairs intestinal barrier defense by modulation of immunoglobulin A transport

BACKGROUND

Increased epithelial permeability may contribute to septic complications after alcohol intoxication. Prior ethanol (EtOH) exposure leads to structural and functional effects on cytoskeletal components important in maintaining barrier integrity. The cytoskeleton is also important in the transcellular transport of proteins including the polymeric immunoglobulin receptor (pIgR) mediated transport of immunoglobulin A (IgA) to the luminal surface of mucosal tissues. We (1) investigated the effects of acute EtOH exposure on cell monolayer barrier integrity and IgA transport and (2) assessed the importance of microtubule function on these functions in vitro.

METHODS

Confluent Madin-Darby canine kidney (MDCK) epithelial cells transfected with pIgR cDNA were exposed to 1% or 5% EtOH, and transcytosis of dimeric IgA was measured. Paclitaxel was used to pretreat a subset of MDCK cells. Results. EtOH exposure resulted in a concentration and time dependent decrease in IgA transcytosis. This was associated with physical derangements in the integrity of the cell monolayer. Pretreatment with paclitaxel completely abrogated these effects.

CONCLUSIONS

EtOH causes both physical and immune derangement of epithelial cell barrier function. Decreased secretory IgA at mucosal surfaces may initiate septic complications after EtOH intoxication.

Race and gender differences in acute respiratory distress syndrome deaths in the United States: an analysis of multiple-cause mortality data (1979- 1996)

OBJECTIVE

Acute respiratory distress syndrome (ARDS) is a devastating clinical disorder that affects critically ill patients with a wide variety of underlying illnesses. Presently, there is limited population-based information concerning both the impact of ARDS on mortality, and the effects of race and gender on national ARDS mortality rates. In this study, we have attempted to evaluate trends over an 18-yr period in deaths associated with ARDS in the United States.

DESIGN

Case series.

PATIENTS

The Multiple-Cause Mortality Files compiled by the National Center for Health Statistics from 1979-1996 contains information on 38,263,780 decedents. We identified 333,004 decedents who had ARDS.

MEASUREMENTS AND MAIN RESULTS

We calculated age-adjusted annual ARDS mortality rates. The annual age-adjusted mortality rate for ARDS initially increased from 1979 (5.0 deaths per 100,000 individuals) to 1993 (8.1 deaths per 100,000 individuals). From 1993 to 1996, the mortality rate for ARDS decreased significantly to 7.4 deaths per 100,000 individuals. Annual ARDS mortality rates have been continuously higher for men when compared with women and for African-Americans when compared with white decedents and decedents of other racial backgrounds. When decedents were stratified by race and gender, African-American men had the highest ARDS mortality rates in comparison to all other subgroups (mean annual mortality rate of 12.8 deaths per 100,000 African-American men).

CONCLUSIONS

Although the annual ARDS mortality rate is slowly declining in the United States, significant race and gender differences in ARDS mortality exist.

Acute respiratory distress syndrome epidemiology and pathophysiology

Acute respiratory distress syndrome is a devastating syndrome of lung injury following known risk factors, with a persistently high mortality. A consensus conference definition of ARDS has been adopted by clinical researchers, but potential problems remain. ARDS may represent more than one entity, and radiographic and mechanical differences between pulmonary versus extrapulmonary initiated ARDS have been described. There is increasing recognition of inflammatory mediators in the pathophysiology of acute lung injury. Surfactant abnormalities contribute to the associated lung dysfunction. A growing body of evidence supports the presence of VILI and a potential mechanism for developing MOSF, and has led to new management strategies. The importances of apoptosis to the repair process, and mechanisms that may lead to persistent fibrosis, such as the activation of the coagulant pathway with fibrin deposition, are increasingly recognized.

Cardiovascular protection by alcohol and polyphenols: role of nitric oxide

Cardiovascular disease, and in particular coronary heart disease (CHD), remains the leading cause of death in both men and women in the United States. Much epidemiologic evidence indicates that alcoholic beverages, and in particular red wine, results in a reduction in cardiovascular risk factors and decreases mortality; however, the mechanisms of this cardiovascular protection remains elusive. This review discusses evidence to suggest that *NO plays a critical role in cardiovascular protection and that nitric oxide synthase (NOS) is the responsible cardioprotective protein (see Bolli et al. 1998. Basic Res. Cardiol. 93: 325-338).

Alcohol, host defence and society

Impaired health caused by alcohol abuse has been known throughout recorded history. Over the past century, alcohol abuse has been clearly linked to host susceptibility to infectious disease, particularly bacterial pneumonia. Recently, both acute and chronic alcohol intake have been shown to result in specific defects in innate and adaptive immunity; these could, in principle, be subjected to specific modulation to overcome the immunosuppressive effects of the most commonly abused substance in the Western world.

Changes in (Na + K)-adenosine triphosphatase activity and ultrastructure of lung and kidney associated with oxidative stress induced by acute ethanol intoxication

STUDY AND OBJECTIVES: (Na + K)-adenosine triphosphatase (ATPase) activity, oxidative stress parameters, and morphologic characteristics of the lung and kidney of rats under acute ethanol intoxication were assessed to investigate the pathogenic mechanism of tissue damage.

DESIGN AND INTERVENTIONS

Adult rats were given ethanol (5.5 g/kg) 3 h before performing the biochemical and morphologic studies. Oxidative stress was assessed by measuring the levels of reduced glutathione (GSH) and glutathione disulfide (GSSG), the activities of key antioxidant enzymes (ie, catalase [CAT], superoxide dismutase [SOD], and glutathione peroxidase [GSH-Px]) and malondialdehyde production. (Na + K)-ATPase, a membrane-bound enzyme, also was assayed.

RESULTS

In the lung, ethanol increased MDA production by 60%, decreased GSH levels by 33%, decreased SOD and GSH-Px activity by 10%, and decreased (Na + K)-ATPase activity by 55%, whereas CAT activity was unaltered. Impaired surfactant secretion and cell adhesion of lung epithelial cells were found. In the kidney, ethanol did not influence the activity of (Na + K)-ATPase or lipid peroxidation, despite the reduction of both GSH and the GSH/GSSG ratio. Focally thickened glomerular basement membrane, apoptosis of foot processes, and tubulointerstitial fibrosis were found.

CONCLUSIONS

These data suggest that oxidative stress plays a role in mediating the ethanol-induced down-regulation of lung (Na + K)-ATPase. GSH depletion seems to be a major determinant of this effect. Independent mechanisms seem to account for the morphologic alterations of these organs.

Acute respiratory distress syndrome: pharmacological treatment options in development

The acute respiratory distress syndrome (ARDS) is a clinical syndrome with primarily supportive management options. Despite extensive basic and clinical investigations, multiple pharmacological and nonpharmacological modalities have been unsuccessful in decreasing mortality. Nonetheless, these efforts have substantially heightened our understanding of ARDS pathophysiology. Investigators continue to create new and more complex therapeutic strategies that may have significant clinical impact. Several pharmacological agents for ARDS are in development and have shown either great promise or are at most, under phase II evaluation. The order in which therapeutic options are presented in this review highlights therapeutic options other than the anti-inflammatory approach. In addition to the anti-inflammatory category, vasodilators, surfactant therapy, immunonutrition and partial liquid ventilation are all being evaluated. Within the anti-inflammatory category. new mechanistic approaches include the 'anti-inflammatory nature' of interleukin-10, the inhibitory aspects of lysophosphatidic acid on endothelial cell permeability, and the use of recombinant human anti-coagulant proteins (activated protein C and tissue factor pathway inhibitor) to reduce the inflammatory cycle that contributes to microvascular thrombi. Previous work with surfactant in ARDS had its limitations, however, these trials were of sufficient success to spawn 2 new synthetic compounds. These new synthetic surfactants incorporate mixtures of phosphatidylcholine and phosphatidylglycerol (the key phospholipids within endogenous surfactant) and either recombinant surfactant protein C or an analogue of surfactant protein B. Recently, the ARDS Network's low tidal volume study has broken the cycle of decades of negative ARDS trials and demonstrated an improvement in mortality. Through better mechanistic approach and study design, investigator compliance with exclusion criteria, and better understanding of the complexities of patient management, the next pharmacological ARDS trials will hopefully be successful and lead to further reductions in patient mortality.

Chronic ethanol ingestion potentiates TNF-alpha-mediated oxidative stress and apoptosis in rat type II cells

In septic patients, chronic alcohol abuse increases the incidence of the acute respiratory distress syndrome (ARDS). Because alveolar type II cell viability is critical for epithelial repair, our objective was to determine if chronic ethanol ingestion increased the sensitivity of type II cells to the inflammatory mediators upregulated during sepsis. In rats chronically fed ethanol, type II cell mitochondrial GSH was depleted, and tumor necrosis factor-alpha (TNF-alpha)-induced generation of mitochondrial reactive oxygen species (ROS) and apoptosis were potentiated. When added to the ethanol diet, the GSH precursor (-)-2-oxo-4-thiazolidinecarboxylic acid (Procysteine; Pro) but not N-acetylcysteine (NAC) normalized type II cell mitochondrial GSH. Likewise, Pro but not NAC normalized TNF-alpha-induced mitochondrial ROS and apoptosis. This suggested that chronic ethanol ingestion potentiated TNF-alpha-induced apoptosis in type II cells via mitochondrial GSH depletion. This may be particularly relevant in ARDS when type II cell viability is critical to repair of the damaged alveolar epithelium and may have important ramifications for the treatment of ARDS patients with a history of alcohol abuse.

Risk factors for ARDS in the United States: analysis of the 1993 National Mortality Followback Study

OBJECTIVE

To identify specific comorbid factors that are present in US decedents with ARDS.

DESIGN

We searched the 1993 National Mortality Followback Study for all decedents who had a code for ARDS mentioned on their death certificate. We also searched for comorbid conditions both on the death certificates (sepsis, medical or surgical misadventures, cirrhosis) and in the study database (current or former smoking, use of alcohol at least 3 d/wk, race, gender, and age). We calculated proportional mortality ratios (PMRs) for these risk factors.

RESULTS

Of the 19,003 decedents for whom data were available, 252 decedents, representing an estimated 19,460 US decedents, had ARDS listed on their death certificate. PMRs among decedents with ARDS were significantly increased for medical or surgical misadventures (PMR, 11.8; 95% confidence interval [CI], 3.8 to 36.7), sepsis (PMR, 5.6; 95% CI, 2.0 to 16.0), nonwhite race (PMR, 2.6; 95% CI, 1.4 to 5.0), and cirrhosis (PMR, 2.2; 95% CI, 1.1 to 4.6). PMRs were increased but not statistically significant for current smokers (PMR, 1.2; 95% CI, 0.5 to 3.0) or former smokers (PMR, 1.8; 95% CI, 0.7 to 4.3) compared to never smokers, and drinking alcohol on > or = 3 d/wk in the year prior to death, when compared to drinking alcohol less than < 3 d/wk (PMR, 1.8; 95% CI, 0.6 to 4.9).

CONCLUSIONS

The results of this study confirm the positive associations between ARDS mortality and the presence of sepsis and cirrhosis, and suggest possible new relationships between ARDS mortality and nonwhite individuals and patients with medical or surgical misadventures.

Selection bias in HMOs: a review of the evidence

Early reviews found that health maintenance organizations (HMOs) attracted healthier beneficiaries in the Medicare program and healthier employees in the market for employer-based insurance. This review finds that HMOs still attract healthier Medicare beneficiaries, that HMOs no longer attract healthier employees, and that HMOs attract healthier Medicaid recipients. This review also found conflicting evidence about whether Medicare HMOs are overpaid, no evidence that HMOs are overpaid in the market for employer-based insurance, and evidence that concerns about overpaying Medicaid HMOs have diminished because many states are adopting mandatory programs.

Ethanol ingestion via glutathione depletion impairs alveolar epithelial barrier function in rats

We determined that rats fed a liquid diet containing ethanol (36% of calories) for 6 wk had decreased (P < 0.05) net vectorial fluid transport and increased (P < 0.05) bidirectional protein permeability across the alveolar epithelium in vivo compared with rats fed a control diet. However, both groups increased (P < 0.05) fluid transport in response to epinephrine (10(-5) M) stimulation, indicating that transcellular sodium transport was intact. In parallel, type II cells isolated from ethanol-fed rats and cultured for 8 days formed a more permeable monolayer as reflected by increased (P < 0.05) leak of [(14)C]inulin. However, type II cells from ethanol-fed rats had more sodium-permeant channels in their apical membranes than type II cells isolated from control-fed rats, consistent with the preserved response to epinephrine in vivo. Finally, the alveolar epithelium of ethanol-fed rats supplemented with L-2-oxothiaxolidine-4-carboxylate (Procysteine), a glutathione precursor, had the same (P < 0.05) net vectorial fluid transport and bidirectional protein permeability in vivo and permeability to [(14)C]inulin in vitro as control-fed rats. We conclude that chronic ethanol ingestion via glutathione deficiency increases alveolar epithelial intercellular permeability and, despite preserved or even enhanced transcellular sodium transport, renders the alveolar epithelium susceptible to acute edematous injury.

Diabetic patients have a decreased incidence of acute respiratory distress syndrome

OBJECTIVE

Our ability to predict which critically ill patients will develop acute respiratory distress syndrome (ARDS) is imprecise. Based on the effects of diabetes mellitus on the inflammatory cascade, we hypothesized that a history of diabetes might alter the incidence of ARDS.

DESIGN

A prospective multicenter study.

SETTING

Intensive care units at four university medical centers.

PATIENTS

One hundred thirteen consecutive patients with septic shock.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All patients were prospectively followed during their intensive care course for the development of ARDS. A history of diabetes was identified in 28% (32/113) of the patients. In this study, nondiabetics were more likely to develop septic shock from a pulmonary source (48%, 39/81) compared with diabetics (25%, 8/32) (p = .02). Forty-one percent (46/113) of the patients with septic shock developed ARDS. Forty-seven percent of the nondiabetic patients developed ARDS compared with only 25% of those with diabetes (p = .03, relative risk = 0.53, 95% confidence interval = 0.28-0.98). In a multivariate logistic regression analysis, when we adjusted for several variables including source of infection, the effect of diabetes on the incidence of ARDS remained significant (p = .03, odds ratio = 0.33, 95% confidence interval = 0.12-0.90).

CONCLUSIONS

In patients with septic shock, a history of diabetes is associated with a lower risk of developing ARDS compared with nondiabetics.

Acute lung injury and acute respiratory distress syndrome in sepsis and septic shock

Sepsis remains the leading cause of ARDS, and ARDS is still an often fatal condition. With our expanding knowledge of the pathobiologic mechanisms and the relationship between these two entities, early recognition, treatment, and prevention of sepsis may prevent or hasten recovery from ARDS. Understanding the biologic markers involved in the complex inflammatory response of sepsis and acute lung injury offers the possibility of future investigations to target treatment based on these mediators.

The effects of chronic alcohol abuse on pulmonary glutathione homeostasis

The incidence and severity of the acute respiratory distress syndrome (ARDS) is increased in critically ill patients with a prior history of chronic alcohol abuse; however, the specific mechanisms responsible for this association are unknown. Recently, we determined that chronic ethanol ingestion in rats decreased the alveolar epithelial lining fluid (ELF) concentration of the antioxidant glutathione (GSH), which is a characteristic finding in patients with ARDS. However, the effects of chronic alcohol abuse on the human alveolar epithelium are essentially unknown. Therefore, as a first step we asked if chronic alcohol abuse, independent of other comorbid conditions, decreases the concentration of GSH in the human lung. We determined that otherwise healthy chronic alcoholics had significantly decreased ELF concentrations of GSH compared with nonalcoholic control subjects (79 micromol [48 to 118 micromol] versus 576 micromol [493 to 728 mmol], p < 0.001). Furthermore, the percentage of GSH in the oxidized form was higher in the chronic alcoholics (9.8% [2.2 to 14.8%] versus 2.8% [0.4 to 4.0%] p = 0.05), indicative of increased utilization of GSH. This is the first report that chronic alcohol abuse alters GSH homeostasis in the human lung, and suggests a potential mechanism by which chronic alcohol abuse predisposes susceptible patients to develop ARDS.

Cigarette smoking, alcohol consumption, and risk of ARDS: a 15-year cohort study in a managed care setting

STUDY OBJECTIVE

To examine the association of cigarette smoking and alcohol consumption with hospital presentation of ARDS in a well-defined, multiethnic population.

DESIGN

Retrospective cohort study.

SETTING

Health maintenance organization in Northern California.

PARTICIPANTS

A total of 121,012 health plan subscribers (54.2% women), aged 25 to 89 years.

OUTCOME MEASURE

Hospital presentation of ARDS (validated by medical chart review) from baseline in 1979 to 1985 through the end of 1993 (median, 9.9 years).

RESULTS

There were 56 cases of ARDS (33 in men, 23 in women). The case fatality rate was 39% in both genders. ARDS was independently related to increasing age (rate ratio of 10 years, 1.38; 95% confidence interval [CI], 1.12 to 1.71), to current smoking of < 20 cigarettes/d (rate ratio vs never cigarette smokers, 2.85; 95% CI, 1. 23 to 6.60), and to current cigarette smoking of > or = 20 cigarettes/d (rate ratio vs never smokers, 4.59; 95% CI, 2.13 to 9.88). No association was observed between alcohol consumption and ARDS.

CONCLUSIONS

The results of this study suggest a relationship (with evidence of dose-response effect) between cigarette smoking and ARDS. Assuming a causal relationship, approximately 50% of ARDS cases were attributable to cigarette smoking.

Consensus conference definitions for sepsis, septic shock, acute lung injury, and acute respiratory distress syndrome: time for a reevaluation

Definitions for sepsis, septic shock, acute lung injury (ALI), and acute respiratory distress syndrome (ARDS) were developed by consensus conferences with the goal of achieving standardization of terminology and improved homogeneity of patient populations in clinical studies. Although such definitions have been useful in epidemiologic investigations, the criteria specified by the consensus conferences are broad and insufficiently specific to address the problem of heterogeneous mechanisms leading to clinical syndromes. An important challenge is to progress from clinical syndromes, as presently defined, to more specific entities that are delineated by alterations in specific immunologic or biochemical pathways. Such mechanistic definitions will provide more homogeneous groups of patients who can be identified at early stages of their clinical course. This approach encourages focused investigation of pathways leading to organ system dysfunction and death and, also, provides an efficient framework for the development of new therapies useful in critically ill patients.

Ethanol ingestion increases activation of matrix metalloproteinases in rat lungs during acute endotoxemia

Previously we reported that alcohol abuse increases the incidence of the acute respiratory distress syndrome (ARDS) in septic patients, and that chronic ethanol ingestion in rats depletes alveolar epithelial glutathione and increases endotoxin-mediated lung edema. In this study we examined a potential mechanism by which ethanol-induced glutathione depletion could predispose to acute lung injury. We hypothesized that glutathione depletion activates matrix metalloproteinases (MMPs), thereby increasing degradation of the alveolar extracellular matrix (ECM) during sepsis. Ethanol-fed rats (20% vol/vol in water for 6 wk) were given endotoxin (2 mg/kg, intraperitoneally) followed 2 h later by lung isolation and ex vivo perfusion with n-formyl-methionyl-leucyl-phenylalanine (fMLP) (10(-)(7) M). Ethanol ingestion increased (p < 0.05) MMP-9 and MMP-2 activity, as determined by zymography, in the lung tissue and lavage fluid compared with control-fed rats, and increased (p < 0.05) levels of the 7S fragment of type IV collagen in the lung lavage fluid. Ethanol ingestion increased activation, but not production, of the MMP-9 and MMP-2 zymogens. Finally, although concomitant ingestion of N-acetylcysteine had no effect (p > 0.05) on MMP production, it increased (p > 0.05) lung glutathione levels, blocked (p < 0.05) MMP-9 and MMP-2 activation, and decreased (p < 0.05) levels of the 7S fragment of type IV collagen. We conclude that chronic ethanol ingestion, via glutathione depletion, activates MMPs during sepsis, thereby increasing degradation of the alveolar epithelial ECM. Lois M, Brown LAS, Moss IM, Roman J, Guidot DM. Ethanol ingestion increases activation of matrix metalloproteinases in rat lungs during acute endotoxemia.

Cholestatic liver injury increases circulating TNF-alpha and IL-6 and mortality after Escherichia coli endotoxemia

We employed a bile duct ligation (BDL) model of cholestatic liver injury to test the hypothesis that this form of preexisting hepatic dysfunction alters the kinetics of circulating TNF-alpha and IL-6 after Escherichia coli endotoxemia, thereby augmenting mortality and lung injury by a TNF-alpha:leukotriene (LT) axis of inflammation. Male rats were catheterized 13 d after BDL or sham surgery and studied while awake 18 to 24 h later. Cholestasis after BDL was confirmed by baseline serum bilirubin (BDL = 7.34 +/- 0.72 mg/dl, mean +/- SEM, n = 17 versus Sham = 0.25 +/- 0.07, n = 20; p < 0.005) and histopathology. Sham and BDL animals received E. coli lipopolysaccharide serotype O55:B5 (LPS, 5 mg/kg i.v.) or 0.9% NaCl (NS) ending at t = 0 and were monitored over 24 h for vital signs and hemodynamics. In parallel studies, lipoxygenase inhibition was performed using diethylcarbamazine or the 5-lipoxygenase activating-protein inhibitor MK-886. Blood was collected at baseline and at t = 1.5, 3.5, and 24 h for formed elements and for serum endotoxin, TNF-alpha, IL-6, bilirubin, and alanine aminotransferase (ALT). Organs were evaluated at 24 h for histopathology, including neutrophil (PMN) densities and wet/dry weight (W/D) ratios. Cholestasis reduced survival after otherwise nonlethal endotoxemia, with seven of 11 BDL + LPS rats dying within 24 h versus no deaths in BDL + NS (n = 6), Sham + LPS (n = 14), or Sham + NS (n = 6) animals (p < 0.01). Despite equivalent serum endotoxin between groups, circulating TNF-alpha was 8-fold higher in BDL + LPS than in Sham + LPS rats at 1.5 and 3.5 h (p < 0.001), whereas serum TNF-alpha did not differ between BDL + NS and Sham + NS rats. IL-6 likewise was increased differentially by 1.5 h in BDL + LPS animals (11.98 +/- 2.42 ng/ml) versus Sham + LPS rats (3.05 +/- 0.58 ng/ml, p < 0.05). Hypothermia, bradycardic hypotension, and leukopenia were most severe and prolonged in BDL + LPS rats, which also had significantly higher ALT values, W/D ratios, and organ PMN counts. LT inhibition failed to reduce BDL-related differences in serum cytokines or survival after endotoxemia. Thus, cholestasis augments inflammatory responses to gram-negative endotoxemia, sensitizing the host to enhanced fluid flux in multiple organs and to mortality by a LT-independent mechanism.

Substance abuse and bone marrow transplant

The purpose of this retrospective study is to test the hypothesis that lifetime substance abuse has an adverse impact on survival after bone marrow transplant (BMT). This study included 17 of 468 patients admitted to the Bone Marrow Transplant Unit at the Brigham and Women's Hospital in Boston, Massachusetts who were identified to have lifetime substance abuse (SA). Seventeen comparison subjects were selected from the admissions roster if they matched for disease and stage, type of transplant, pretransplant conditioning regimen, and age, but did not have SA. The medical records of all 34 patients were then reviewed by expert substance abuse clinicians for confirmation of SA and course of transplant. Survival time was calculated from the date of BMT admission to the date of last contact. Survival data were analyzed through Kaplan Meier survival curves and log rank tests for association of survival time with lifetime SA, both before and after stratification for history of cigarette smoking and type of transplant. The patients with and without SA were well matched for all clinical factors. Substance abuse or dependence was confirmed in all 17 patients, with alcohol (71%), marijuana (30%), and opiates (30%) identified as the principal substances of abuse. Survival analysis demonstrated reduced survival times for patients with SA, p = .0022. This difference persisted after stratifying for type of transplant and cigarette smoking. Trends in different survival times by type of transplant (p = .054) and by history of cigarette smoking (p = .07) were also identified. Lifetime substance abuse or dependence appears to have an adverse association with survival after bone marrow transplant when other clinical factors are equal.