MOF, MODS, and SIRS: what is in a name or an acronym?

Is MOF an outcome parameter or a transient, adaptive state in critical illness?

PURPOSE OF REVIEW

The term 'multiorgan failure' (MOF) carries the negative connotation of major homeostatic breakdown and severe malfunction. However, this traditional paradigm may not be necessarily accurate. This review will investigate the rationale for no longer considering MOF to be simply a 'failed' pathophysiological state.

RECENT FINDINGS

Multiorgan failure is characterized by a hypometabolic, immunodepressed state with clinical and biochemical evidence of decreased functioning of the body's organ systems. Notwithstanding these findings, evidence for cell death is scarce and organ recovery is frequently the rule in surviving patients without pre-existing organ disease. Decreased mitochondrial activity appears to play a key role in the processes underlying MOF, both as a victim and a player. Reduced ATP production will compromise normal metabolic functioning. To protect itself from dying, the cell may adapt by decreasing its metabolic rate, and this is clinically manifest as organ dysfunction. Mitochondrial modulation may thus represent an important therapeutic target.

SUMMARY

The concept of MOF could be revisited as a transient state of metabolic shutdown analogous to hibernation. Avoiding the detrimental effects of inappropriate and counter-adaptive iatrogenic interventions is an important cornerstone of therapeutic management.

Metabolic consequences of acute limb ischemia and their clinical implications

Acute limb ischemia is a common medical condition resulting from arterial embolization, in situ thrombosis, trauma, and other causes. The severity of injury is related to the duration of ischemia and the effects of reperfusion. Metabolic consequences of reperfusion injury can be variable, ranging from transient symptoms in the lower extremity to systemic inflammation with multiple organ dysfunction. This article provides an overview of some of the key mediators of reperfusion injury. Additional discussion is focused on the clinical effects of reperfusion in the extremity, as well as the pulmonary, cardiac, and renal organ systems. A better understanding of these processes may result in improved patient outcomes and decreased mortality.

Toll-like receptors in ischemia-reperfusion injury

Ischemia-reperfusion (I/R) injuries are implicated in a large array of pathological conditions such as myocardial infarction, cerebral stroke, and hepatic, renal, and intestinal ischemia, as well as following cardiovascular and transplant surgeries. The hallmark of these pathologies is excessive inflammation. Toll-like receptors (TLRs) are recognized as one of the main contributors to pathogen-induced inflammation and, more recently, injury-induced inflammation. Endogenous ligands such as low-molecular hyaluronic acid, fibronectin, heat shock protein 70, and heparin sulfate were all found to be cleaved in the inflamed tissue and to activate TLR2 and TLR4, initiating an inflammatory response even in the absence of pathogens and infiltrating immune cells. In this review, we discuss the contribution of TLR activation in hepatic, renal, cerebral, intestinal, and myocardial I/R injuries. A greater understanding of the role of TLRs in I/R injuries may aid in the development of specific TLR-targeted therapeutics to treat these conditions.

Intraperitoneal injection of extracted microcystins results in hypovolemia and hypotension in crucian carp (Carassius auratus)

Circulatory responses of crucian carp injected intraperitoneally with extracted microcystins (MCs) were studied at sublethal and lethal doses (150 and 600 microg MC kg(-1) body mass, respectively). Mean arterial blood pressure (MAP), heart rate, hematocrit (Hct), red blood cell (RBC) counts, and circulating blood volume (BV) were assayed at 0, 1, 3, 12, 24, and 48 h post-toxin administration. MAP decreased significantly in a dose-dependent manner over time. Within the 48-h test period, the lethal dose as well as the sublethal dose resulted in a steady decline of MAP without recovery. Heart rate significantly increased within 24 h post-injection as blood pressure significantly dropped, then showed a terminal decline to the control level. The dose-dependent decreases in BV and Hct were directly related to the drop in MAP. Intraperitoneal injection of a lethal dose of MCs led to hepatic and gill hemorrhage. Consequently, crucian carp given MCs suffered from hypovolemic hypotensive shock.

Validation of postinjury multiple organ failure scores

Most multiple organ failure (MOF) scores were developed over a decade ago, but little has been done in terms of validation and to understand the differences between populations identified by each of them. Given the lack of a gold standard, validation must rely on association with objective adverse outcomes. Thus, we propose to (a) validate two widely accepted MOF scores (Denver and Marshall), examining their association with adverse outcomes in a postinjury population; and (b) compare risk factors, characteristics, and outcomes of patients identified by each score. The Denver MOF score grades (from 0-3) four organ dysfunctions (lung, kidney, liver, and heart) and defines MOF as a total score more than 3. The Marshall score grades, in addition, central nervous system and hematologic dysfunction (total of six organs on a 0- to 4-point scale). Using a prospectively collected data set, MOF was scored daily by both scores for 1,389 consecutive trauma patients with Injury Severity Score of more than 15 admitted from 1992 to 2004. Risk factors, clinical outcomes (death, ventilator-free days), and resource utilization outcomes (mechanical ventilation time, length of stay in the intensive care unit) were evaluated. Both scores were associated with areas under the receiver operating characteristic curves of 80 or greater (ideal value = 100), with values for the Denver score being slightly greater (albeit not significantly) regarding prediction of most outcomes. Values of sensitivity and specificity were more than 70% for death and ventilator-free days (with the Denver score showing a consistent trend toward greater specificity), but either sensitivity or specificity was less than 70% for mechanical ventilation time and length of stay in the intensive care unit, suggesting that these scores are appropriately biased toward clinical outcomes as opposed to resource utilization. Both scores performed well, with the Denver MOF score showing greater specificity, which, coupled with its simplicity, makes it an attractive tool for both the research and clinical environments. Basic concepts of each score can probably be combined to produce an improved MOF score.

Estrogen suppresses cardiac IL-6 after trauma-hemorrhage via a hypoxia-inducible factor 1 alpha-mediated pathway

Cardiac dysfunction is a major concern after trauma-hemorrhage, and increased IL-6 is one of the underlying causes for producing the dysfunction. Studies have shown that administration of 17beta-estradiol (estrogen) after trauma-hemorrhage normalized cardiac IL-6 levels and restored cardiac functions under those conditions. Because hypoxia-inducible factor (HIF) 1 alpha is expressed during hypoxia and cellular stress and up-regulates the expression of IL-6, we hypothesized that HIF-1 alpha induces the increased cardiac IL-6 after trauma-hemorrhage and that estrogen suppresses this induction. To examine this, C3H/HeN mice were subjected to trauma-hemorrhage or sham operation. Vehicle, the HIF-alpha inhibitor YC-1 [3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole, a novel activator of platelet guanylate cyclase], or estrogen was administered to trauma-hemorrhage and sham groups during resuscitation. Mice were killed at 2 h after resuscitation, and cardiac IL-6, HIF-1 alpha, and nuclear factor (NF) kappaB activities were measured. IL-6, NF-kappaB, and HIF-1 alpha levels were markedly elevated after trauma-hemorrhage; all of these parameters were normalized by estrogen as well as YC-1 administration after trauma-hemorrhage. Because elevated IL-6 levels after trauma-hemorrhage were decreased with YC-1 treatment, it indicates that IL-6 expression in cardiomyocytes is induced via HIF-1 alpha. In addition, estrogen decreased the elevated HIF-1 alpha, NF-kappaB, and IL-6 levels after trauma-hemorrhage. These results indicate that the beneficial effects of estrogen on cardiac function after trauma-hemorrhage seem to be mediated by the inhibition of HIF-1 alpha expression and activity.

Genomic expression profiling across the pediatric systemic inflammatory response syndrome, sepsis, and septic shock spectrum

OBJECTIVES

To advance our biological understanding of pediatric septic shock, we measured the genome-level expression profiles of critically ill children representing the systemic inflammatory response syndrome (SIRS), sepsis, and septic shock spectrum.

DESIGN

Prospective observational study involving microarray-based bioinformatics.

SETTING

Multiple pediatric intensive care units in the United States.

PATIENTS

Children <or=10 years of age: 18 normal controls, 22 meeting criteria for SIRS, 32 meeting criteria for sepsis, and 67 meeting criteria for septic shock on day 1. The available day 3 samples included 20 patients still meeting sepsis criteria, 39 patients still meeting septic shock criteria, and 24 patients meeting the exclusive day 3 category, SIRS resolved.

INTERVENTIONS

None other than standard care.

MEASUREMENTS AND MAIN RESULTS

Longitudinal analyses were focused on gene expression relative to control samples and patients having paired day 1 and day 3 samples. The longitudinal analysis focused on up-regulated genes revealed common patterns of up-regulated gene expression, primarily corresponding to inflammation and innate immunity, across all patient groups on day 1. These patterns of up-regulated gene expression persisted on day 3 in patients with septic shock, but not to the same degree in the other patient classes. The longitudinal analysis focused on down-regulated genes demonstrated gene repression corresponding to adaptive immunity-specific signaling pathways and was most prominent in patients with septic shock on days 1 and 3. Gene network analyses based on direct comparisons across the SIRS, sepsis, and septic shock spectrum, and all available patients in the database, demonstrated unique repression of gene networks in patients with septic shock corresponding to major histocompatibility complex antigen presentation. Finally, analyses focused on repression of genes corresponding to zinc-related biology demonstrated that this pattern of gene repression is unique to patients with septic shock.

CONCLUSIONS

Although some common patterns of gene expression exist across the pediatric SIRS, sepsis, and septic shock spectrum, septic shock is particularly characterized by repression of genes corresponding to adaptive immunity and zinc-related biology.

Postoperative vasopressin and copeptin levels in noncardiac surgery patients: a prospective controlled trial

Further information on the endogenous arginine vasopressin (AVP) response in patients with postoperative systemic inflammatory response syndrome (SIRS) and vasodilatory shock would provide more insight into the pathophysiology of SIRS-associated cardiovascular failure and help indicate AVP therapy. Patients after uncomplicated abdominal surgery without SIRS (n = 10), critically ill patients after noncardiac surgery with SIRS (n = 9), and patients with SIRS plus vasodilatory shock (n = 22) were included in this prospective trial. Plasma AVP (radioimmunoassay) and copeptin (immunoluminometric assay) concentrations together with clinical parameters were documented daily during the first 7 days postoperative. The AVP response significantly differed between the three groups. Patients without SIRS had lower AVP concentrations than SIRS patients with (P = 0.001) or without shock (P = 0.003). Patients with SIRS and shock had higher AVP levels than patients with SIRS alone (P < 0.001). Arginine vasopressin decreased over time (P = 0.007) in all groups. At day 28, nonsurvivors had higher AVP levels than did survivors (P < 0.001). In SIRS patients without shock, serum osmolarity was indirectly associated with AVP levels, whereas mean arterial blood pressure and serum osmolarity were associated with AVP in SIRS patients with shock. Arginine vasopressin and copeptin correlated significantly with each other (P < 0.001; r = 0.76). In patients without hemofiltration, copeptin levels predicted 28-day mortality with high sensitivity and specificity. The postoperative AVP response in noncardiac surgery patients seems well maintained. The possibility that AVP plays a contributory role in the failure to restore vascular tone in patients with vasodilatory shock cannot be excluded but seems less important than in septic or postcardiotomy shock.

Comparison of the effects of aging and IL-6 on the hepatic inflammatory response in two models of systemic injury: scald injury versus i.p. LPS administration

Regardless of age, a marked elevation in circulating IL-6 levels correlates with increased mortality after injury or an inflammatory challenge. We previously reported that aged IL-6 knockout mice given LPS have improved survival and reduced inflammatory response than LPS-treated aged wild type (WT) mice. Herein, we analyzed the effects of aging and IL-6 on the hepatic inflammatory response in two models of systemic injury: dorsal scald (burn) injury versus intraperitoneal LPS administration. At 24 h after burn injury, circulating alanine aminotransferase and hepatic neutrophil accumulation were comparable regardless of age or IL-6 deficiency. However, at this same time point, these indicators of liver damage, in addition to hepatic levels of KC, a neutrophil chemoattractant, were increased in aged WT mice given LPS relative to young WT mice given LPS. The hepatic injury was drastically reduced in aged IL-6 knockout mice given LPS as compared with LPS-exposed aged WT mice. Our results suggest that the nature of the insult will determine the degree of remote injury in aged animals. In addition, the role of IL-6 as a contributing factor of tissue injury may be insult specific.

Systematic analysis of the salutary effect of estrogen on cardiac performance after trauma-hemorrhage

Although 17beta-estradiol (estrogen) and estrogen receptor (ER) agonist administration after trauma-hemorrhage improves cardiac function, it remains unknown what the optimal estrogen or ER agonist dosage is to elicit this beneficial effect. To study this, the dose-dependent effects of estrogen, propylpyrazole triol (ER-alpha agonist), and diarylpropionitrile (DPN; ER-beta agonist) on heart performance (+dP/dt) were determined in sham rats and in experimental animals at the time of maximal bleedout (MBO) or at 2 h after trauma-hemorrhage. The results showed that estrogen and DPN induced dose-dependent increases in the maximal rate of left ventricular pressure increase (+dP/dt) in all groups, whereas propylpyrazole triol was ineffective at all doses. The maximal dose and the 50% effective dose of DPN were approximately 100-fold lower than those of estrogen. The half-life of estrogen in plasma was approximately 25 min in sham and MBO groups. A positive correlation between the estrogen-induced increase in +dP/dt and survival in MBO rats were observed. These results collectively suggest that the salutary effects of estrogen on cardiac performance are dose-dependent and mediated via ER-beta.

Prevention of hemorrhagic shock-induced intestinal tissue injury by glutamine via heme oxygenase-1 induction

Hemorrhagic shock (HS) is an oxidative stress that causes intestinal tissue injury. Heme oxygenase 1 (HO-1) is induced by oxidative stress and is thought to play an important role in the protection of tissues from oxidative injury. We previously reported the ileum to be the most susceptible to HS-induced tissue injury site in the intestine because HO-1 induction is the lowest at this site. We also previously demonstrated that glutamine (GLN) significantly induced HO-1 in the lower intestinal tract. In the present study, we investigated whether GLN pretreatment improves HS-induced intestinal tissue injury in the ileum by HO-1 induction. Treatment of rats with GLN (0.75 g/kg, i.v.) markedly induced functional HO-1 protein in mucosal epithelial cells in the ileum. Glutamine treatment before HS (MAP of 30 mmHg for 60 min) significantly ameliorated HS-induced mucosal inflammation and apoptotic cell death in the ileum, as judged by significant decreases in gene expression of TNF-alpha, iNOS, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1, myeloperoxidase activity, the number of infiltrated neutrophils, DNA fragmentation by in situ oligo ligation assay, and activated caspase-3 expression, and by increases in gene expression of IL-10 and Bcl-2. In contrast, treatment with tin mesoporphyrin, a specific inhibitor of HO activity, abolished the beneficial effect of GLN pretreatment. These findings indicate that GLN pretreatment significantly ameliorated tissue injury in the ileum after HS by inducing HO-1. Glutamine treatment may thus protect mucosal cells from HS-induced oxidative damage via the anti-inflammatory and antiapoptotic properties of HO-1.

Aging and animal models of systemic insult: trauma, burn, and sepsis

In the acute-care setting, it is widely accepted that elderly patients have increased morbidity and mortality compared with young healthy patients. The reasons for this, however, are largely unknown. Although animal modeling has helped improve treatment strategies for young patients, there are a scarce number of studies attempting to understand the mechanisms of systemic insults such as trauma, burn, and sepsis in aged individuals. This review aims to highlight the relevance of using animals to study the pathogenesis of these insults in the aged and, despite the deficiency of information, to summarize what is currently known in this field.

Polymorphisms in innate immunity genes predispose to bacteremia and death in the medical intensive care unit

OBJECTIVE

Critically ill patients are at risk of sepsis, organ failure, and death. Studying the impact of genetic determinants may improve our understanding of the pathophysiology and allow identification of patients who would benefit from specific treatments. Our aim was to study the influence of single nucleotide polymorphisms in selected genes involved in innate immunity on the development of bacteremia or risk of death in patients admitted to a medical intensive care unit.

DESIGN, SETTING, AND PATIENTS

DNA was available from 774 medical intensive care unit patients. We selected 31 single nucleotide polymorphisms in 14 genes involved in host innate immune defense. Serum levels of MASP2 and chemotactic capacity, phagocytosis, and killing capacity of monocytes at admission were quantified. Univariate Kaplan-Meier estimates with log-rank analysis and multivariate logistic regression were performed. Bootstrap resampling technique and ten-fold cross-validation were used to assess replication stability, prognostic importance of the variables, and repeatability of the final regression model.

MAIN RESULTS

Patients with at least one NOD2 variant were shown to have a reduced phagocytosis by monocytes (p = 0.03) and a higher risk of bacteremia than wild-type patients (p = 0.02). The NOD2/TLR4 combination was associated with bacteremia using survival analyses (time to bacteremia development, log-rank p < 0.0001), univariate regression (p = 0.0003), and multivariate regression analysis (odds ratio [OR] 4.26, 95% confidence interval [CI] 1.85-9.81; p = 0.0006). Similarly, the same combination was associated with hospital mortality using survival analysis (log-rank p = 0.03), univariate regression (p = 0.02), and multivariate regression analysis (OR 2.27, 95% CI 1.09-4.74; p = 0.03). Also variants in the MASP2 gene were significantly associated with hospital mortality (survival analysis log-rank-p = 0.003; univariate regression p = 0.02; multivariate regression analysis OR 2.35, 95% CI 1.38-3.99; p = 0.002).

CONCLUSIONS

Functional polymorphisms in genes involved in innate immunity predispose to severe infections and death, and may become part of a risk model, allowing identification of patients at risk, who could benefit from early introduction of specific preventive or therapeutic interventions.

Effect of interleukin-15 on depressed splenic dendritic cell functions following trauma-hemorrhage

Although trauma-hemorrhage (T-H) induces suppressed splenic dendritic cell (DC) maturation and antigen presentation capacity, it remains unclear whether IL-15 modulates splenic DC functions. The aim of this study therefore was to investigate the effect of IL-15 on splenic DC functions after T-H. Male C3H/HeN mice (6-8 wk old) were randomly assigned to T-H or sham operation. T-H was induced by midline laparotomy and approximately 90 min of hemorrhagic shock (blood pressure 35 mmHg), followed by fluid resuscitation (4x the shed blood volume in the form of Ringer lactate). Two hours later, mice were killed, splenic DCs were isolated, and the effects of exogenous IL-15 on their costimulatory factors, major histocompatibility class II expression, ability to produce cytokines, and antigen presentation were measured. The results indicate that IL-15 production capacity of splenic DCs was reduced following T-H. Ex vivo exposure to IL-15 attenuated the suppressed production of TNF-alpha, IL-6, and IFN-gamma from splenic DCs following T-H. In addition, expression of surface antigen studies demonstrate that exogenous IL-15 attenuated T-H-induced downregulation of the activation of DC. The suppressed splenic DC antigen presentation function following T-H was also attenuated by IL-15 treatment. Moreover, IL-15 enhanced IL-12-induced IFN-gamma production and antigen presentation by splenic DCs. These data suggest that ex vivo treatment with IL-15 following T-H provides beneficial effects on splenic DCs. The depression in IL-15 production by splenic DCs could contribute to the host's enhanced susceptibility to infections following T-H.

Early versus late onset of multiple organ failure is associated with differing patterns of plasma cytokine biomarker expression and outcome after severe trauma

Although multiple organ failure (MOF) remains the leading cause of death after trauma, the pathogenic cellular and molecular mechanisms underlying MOF are poorly understood. In addition to proinflammatory and anti-inflammatory mediator cascades, the temporal onset of MOF has generated recent interest because the organ systems involved into MOF seem to deteriorate in a time-dependent fashion after trauma. We therefore investigated the temporal course of MOF in traumatized human patients and evaluated and compared the distribution patterns of cytokine expression, including interleukin (IL) 6, IL-8, IL-10, and the soluble tumor necrosis factor-[alpha] receptors sTNF-R p55 and sTNF-R p75 in early-onset versus late-onset MOF. In addition, we analyzed the predictive value of cytokine biomarkers of MOF and lethal outcome. In a prospective observational cohort study conducted at three trauma centers, all patients (n = 352) admitted to two level 1 trauma centers in Germany were enrolled in the study based on the following inclusion criteria: severe traumatic brain injury (TBI) with a Glasgow Coma Scale (GCS) score of 8 or lower and/or distinct changes in cranial computed tomography and/or multiple injuries (MT) to the body (at least two regions had Abbreviated Injury Scale score of 3 or higher). The incidence of MOF was evaluated using the modified Goris-MOF score. The temporal onset of MOF was divided into early-onset MOF (EMOF, developing on days 0-3), late-onset MOF (LMOF, developing on days 4-10), combined early-onset and late-onset MOF (CMOF), and patients never showing signs of MOF during the observation period. In addition, the levels of the serum cytokine markers IL-6, IL-8, IL-10, sTNF-R p55, and sTNF-R p75 were analyzed at specific posttraumatic time points using established enzyme-linked immunosorbent assay techniques. A total of 352 patients (274 men and 78 women; TBI, 101; TBI + MT, 125; MT, 126) were enrolled into the study. Patients assigned to the EMOF group showed specific disruption of pulmonary and cardiocirculatory function, whereas LMOF was significantly associated with hepatic failure. The patients without signs of MOF and the EMOF patients had the same risk of lethal outcome (8.2% vs. 7.5%); LMOF and CMOF were found to be associated with a 3- to 4-fold increase in mortality (38.5% vs. 30.6%, respectively). Analysis of cytokine serum biomarkers revealed that patients with LMOF showed a biphasic elevation of IL-6 and significantly higher sTNF-R concentrations than did all other subgroups (P < 0.001). In addition, the initial values (days 0-1) of sTNF-R p55 and sTNF-R p75 expression levels had a good predictive capacity for the development of LMOF (p55, 0.75; p75, 0.72); values greater than 0.65 were accepted to have a predictive capacity. These results demonstrate that mortality differs significantly between the development of EMOF and LMOF after traumatic injury. Our results also suggest that serum cytokine measurements may be important early biochemical markers for predicting the development of delayed MOF.

ETANERCEPT REDUCES ACUTE TISSUE INJURY AND MORTALITY ASSOCIATED TO ZYMOSAN-INDUCED MULTIPLE ORGAN DYSFUNCTION SYNDROME

It has been well demonstrated that TNF-alpha is integral to the pathogenesis of multiple organ dysfunction syndrome (MODS). In this study, we investigate the effects of etanercept (10 mg/kg, s.c.), a specific TNF-alpha-soluble inhibitor, on the acute phase and late mortality in a murine model of MODS of nonseptic origin induced by zymosan (500 mg/kg, suspended in saline solution, i.p.). Etanercept was administered 1 h after the injection of zymosan. Animals were killed after 18 h. In another set of experiments, mice were monitored for systemic toxicity, loss of body weight, and mortality for 12 days. Sham-treated and TNF receptor 1 (TNFR1)-deficient animals were used as control. Treatment of mice with Etanercept and TNFR1 gene deletion decreased the peritoneal exudation and the migration of neutrophils caused by zymosan. In addition, pharmacological and genetic neutralization of TNF-alpha attenuated pancreas and ileum injury (histology), the increase in myeloperoxidase activity in the ileum and in the lung, and the formation of TNF-alpha and IL-1beta. Immunohistochemical analysis for TNF-alpha, transforming growth factor beta, and vascular endothelial growth factor revealed a positive staining in pancreas and ileum sections. The degree of immunostaining was markedly reduced after etanercept treatment and in TNFR1 knockout mice. Furthermore, TNF-alpha neutralization decreased the potent apoptotic stimulus induced by zymosan. All of these findings ultimately led to an amelioration of organ functions at 18 h and to a better survival rate at 12 days. Therefore, we demonstrate that etanercept reduces acute tissue injury and mortality associated to MODS of nonseptic origin in mice.

Trauma-hemorrhage inhibits splenic dendritic cell proinflammatory cytokine production via a mitogen-activated protein kinase process

Although splenic dendritic cell (DC) functions are markedly altered following trauma-hemorrhage, the mechanism(s) responsible for the altered DC functions remains unknown. We hypothesized that trauma-hemorrhage inhibits DC function via suppressing toll-like receptor 4 (TLR4) expression and mitogen-activated protein kinases (MAPKs). To examine this, male C3H/HeN (6–8 wk) mice were randomly assigned to sham operation or trauma-hemorrhage. Trauma-hemorrhage was induced by midline laparotomy and ∼90 min of hypotension [blood pressure (BP) 35 mmHg], followed by fluid resuscitation (4× the shed blood volume in the form of Ringer lactate). Two hours later, mice were euthanized, splenic DCs were isolated, and the changes in their MAPK activation, TLR4-MD-2 expression, and ability to produce cytokines were measured. The results indicate that trauma-hemorrhage downregulated the lipopolysaccharide (LPS)-induced MAPK activation in splenic DCs. In addition to the decrease in MAPK activation, surface expression of TLR4-MD-2 was suppressed following trauma-hemorrhage. Furthermore, LPS-induced cytokine production from splenic DCs was also suppressed following trauma-hemorrhage. These findings thus suggest that the decrease in TLR4-MD-2 and MAPK activation may contribute to the LPS hyporesponsiveness of splenic DCs following trauma-hemorrhage. Hyporesponsiveness of splenic DCs was also found after stimulation with the TLR2 agonist zymosan. Our results may thus explain the profound immunosuppression that is known to occur under those conditions.

Antioxidant supplementation in sepsis and systemic inflammatory response syndrome

OBJECTIVE

Summarize the current knowledge about oxidative stress-related organ dysfunction in inflammatory and septic conditions, and its potential prevention and treatment by antioxidants in critically ill patients, focusing on naturally occurring antioxidants and clinical trials.

STUDY SELECTION

PubMed, MEDLINE, and personal database search.

SYNTHESIS

Plasma concentrations of antioxidant micronutrients are depressed during critical illness and especially during sepsis. The causes of these low levels include losses with biological fluids, low intakes, dilution by resuscitation fluids, as well as systemic inflammatory response syndrome-mediated redistribution of micronutrients from plasma to tissues. Numerous clinical trials have been conducted, many of which have shown beneficial effects of supplementation. Interestingly, among the candidates, glutamine, glutathione, and selenium are linked with the potent glutathione peroxidase enzyme family at some stage of their synthesis and metabolism.

CONCLUSIONS

Three antioxidant nutrients have demonstrated clinical benefits and reached level A evidence: a) selenium improves clinical outcome (infections, organ failure); b) glutamine reduces infectious complication in large-sized trials; and c) the association of eicosapentaenoic acid and micronutrients has significant anti-inflammatory effects. Other antioxidants are still on the clinical benchmark level, awaiting well-designed clinical trials.

Comparison of longitudinal leukocyte gene expression after burn injury or trauma-hemorrhage in mice

A primary objective of the large collaborative project entitled "Inflammation and the Host Response to Injury" was to identify leukocyte genes that are differentially expressed after two different types of injury in mouse models and to test the hypothesis that both forms of injury would induce similar changes in gene expression. We report here the genes that are expressed in white blood cells (WBCs) and in splenocytes at 2 h, 1 day, 3 days, and 7 days after burn and sham injury or trauma-hemorrhage (T-H) and sham T-H. Affymetrix Mouse Genome 430 2.0 GeneChips were used to profile gene expression, and the results were analyzed by dCHIP, BRB Array Tools, and Ingenuity Pathway Analysis (IPA) software. We found that the highest number of genes differentially expressed following burn injury were at day 1 for both WBCs (4,989) and for splenocytes (4,715) and at day 1 for WBCs (1,167) and at day 3 for splenocytes (1,117) following T-H. The maximum overlap of genes that were expressed after both forms of injury were at day 1 in WBCs (136 genes) and at day 7 in splenocytes (433 genes). IPA revealed that the cell-to-cell signaling, cell death, immune response, antiapoptosis, and cell cycle control pathways were affected most significantly. In summary, this report provides a database of genes that are modulated in WBCs and splenocytes at sequential time points after burn or T-H in mice and reveals that relatively few leukocyte genes are expressed in common after these two forms of injury.

17beta-Estradiol's salutary effects on splenic dendritic cell functions following trauma-hemorrhage are mediated via estrogen receptor-alpha

Although 17beta-estradiol administration following trauma-hemorrhage attenuates Kupffer cell, splenic and peritoneal macrophage functions, it remains unknown whether 17beta-estradiol has any salutary effects on splenic dendritic cell (DC) functions and if so, whether such effects are mediated via the estrogen receptors (ER). We hypothesized that 17beta-estradiol administration following trauma-hemorrhage has salutary effects on splenic DC functions. Male C3H/HeN (6-8 weeks) mice were randomly assigned to sham operation or trauma-hemorrhage. Trauma-hemorrhage was induced by midline laparotomy and approximately 90 min of hemorrhagic shock (blood pressure [BP] 35 mmHg), followed by fluid resuscitation (4x the shed blood volume in the form of Ringer's lactate). Estrogen receptor (ER)-alpha agonist propyl pyrazole triol (PPT; 5microg/kg), ER-beta agonist diarylpropionitrile (DPN; 5microg/kg), 17beta-estradiol (50microg/kg), or vehicle (10% DMSO) was injected subcutaneously during resuscitation. Two hours later, the mice were sacrificed, splenic DCs were isolated and the changes in their apoptosis, co-stimulating factors and MHC class II expression, ability to produce cytokines, and antigen presentation capacity were measured. Apoptosis of splenic DC increased following trauma-hemorrhage; however, 17beta-estradiol administration after trauma-hemorrhage normalized the rate of apoptosis. Moreover, splenic DC cytokines production, co-stimulating factors and MHC class II expression, and antigen presentation capacity were significantly decreased following trauma-hemorrhage; however, 17beta-estradiol as well as PPT also prevented these depressions. In contrast, DPN did not attenuate splenic DC functions following trauma-hemorrhage. Since PPT administration following trauma-hemorrhage was more effective in normalizing splenic DC functions than DPN, the salutary effects of 17beta-estradiol on splenic DC functions are mediated predominantly via ER-alpha.

Effect of Lactobacillus plantarum enteral feeding on the gut permeability and septic complications in the patients with acute pancreatitis

OBJECTIVE

To study the effect of the Lactobacillus plantarum (LP) enteral feeding on the gut permeability and sepsis in the patients with acute pancreatitis.

SUBJECTS

Seventy-six subjects who stayed over 1 week in the hospital completed the study. Subjects were not treated with any lactobacillus supplement before the intervention.

METHODS

Seventy-six patients with acute pancreatitis were randomly divided into two groups, parenteral nutrition (PN) group (n=38) and ecoimmunonutrition (EIN) group supplied by LP enteral feeding (n=36). The acute physiology and chronic health evaluation score, Balthazar CT score, CRP, fecal bacterial species and DNA fingerprint profiles as well as the potentially pathologenic organisms in nasogastric aspirate were determined on the day of admission and on the 8 day. The intestinal permeability was assessed by measurement of the ratio of lactulose/rhamnose on the day of admission and on days 5 and 8. The rate of organ failure, septic complications and death cases were evaluated at the 8 day.

RESULTS

Following 7 days treatment, 38.9% patients in the EIN group were colonized with multiple organisms compared to 73.7% in the PN group (P<0.01), and 30.6% patients in the EIN grew potentially pathogenic organisms compared to 50% patients in PN group (P<0.05). The fecal bacterial DNA fingerprint profiles were less, the amount of lactobacteria and bifidobacteria decreased, and the amount of enterococci increased in PN group as compared with EIN group, P<0.05. By day 8, the lactulose/rhamnose ratio in EIN group were lower than that in PN group at days 5 and 8, P<0.05. The patients with LP got a better clinical outcomes as compared with the patients with PN.

CONCLUSION

EIN enteral feeding can attenuate disease severity, improve the intestinal permeability and clinical outcomes.

Local and systemic impacts of pleural oxygen exposure in thoracotomy

The pleural cavity is normally in a state of negative pressure and low oxygen tension. It is exposed to the atmosphere during thoracic surgery. However, no reports of pathophysiological investigation of the effects of pleural oxygen exposure involved in thoracotomy are available. In this study, the effects of pleural oxygen exposure on systemic and pleural inflammation were investigated. Male Wistar rats (9 weeks old) were placed on mechanical ventilation and underwent thoracotomy with lipopolysaccharide (LPS) administration, which simulates latent inflammatory condition. The pleural cavity was exposed to nitrogen (N(2) thoracotomy group), air (20% oxygen, air thoracotomy group), or 100% oxygen (O(2) thoracotomy group) under mechanical ventilation for 2 h. Animals were sacrificed 2 h or 8 h after LPS administration, and inflammatory indices (plasma tumor necrosis factor-alpha and interleukin-6, histology) were examined. For examination of inflammatory mediators, pleural effusion was added to cultured RAW264 cells, a murine macrophage cell line, and tumor necrosis factor-alpha levels in supernatant were measured. The capacity of pleural superoxide generation was investigated without LPS administration. Results showed increases in plasma interleukin-6 concentration and lung injury in the air and O(2) thoracotomy groups. Pleural oxygen exposure stimulated pleural superoxide generation, and increased pleural 4-hydroxy-2-nonenal and lung lipid peroxide concentrations. Tumor necrosis factor-alpha levels in cell culture supernatants were increased by the addition of pleural effusion from the air and O(2) thoracotomy groups. In conclusion, pleural oxygen exposure induced pleural oxidative injury and aggravated latent systemic inflammatory response.