The TNF-α (-238 G/A) polymorphism could protect against development of severe sepsis

Primary responses in sepsis-mediated inflammation are regulated by pro-inflammatory cytokines. Variations in the cytokine genes might modify their transcription or expression, plasma cytokines levels and response to sepsis. Activation protein-1 (AP-1) and NF-κB regulate cytokines gene expression in sepsis. A total of 90 severely septic and 91 non-infected patients were prospectively studied. IL-1α (-889 C/T), IL-1β (+3954 C/T), IL-6 (-174 G/C), TNF-α (-238 G/A), TNF-α (-308G/A), IL-8 (-251A/T) and IL-10 (-1082 G/A) SNPs, plasma IL-1β, IL-4, IL-6, IL-8, IL-10, IL-13, IFN-γ, TNF-α and monocyte chemoattractant protein 1 (MCP-1) levels, and AP-1 and NF-κB gene expression by neutrophils were assessed. A allele carriers of TNF-α (-238 G/A) SNP were less frequent among septic patients. IL-6, IL-8, IL-10, TNF-α and MCP-1 levels were higher, and AP-1 and NF-κB gene expressions lower in septic patients. Sepsis was independently associated with higher fibrinogen, neutrophils counts and IL-8 levels, lower prothrombin, absence of the variant A allele of the TNF-α (-238 G/A) SNP, and haemodynamic failure. Death was independently associated with a higher APACHE II score, higher IL-8 levels, and the diagnosis of sepsis. TNF-a (-238 G/A) SNP could protect against sepsis development. Higher IL-8 levels are predictive of sepsis and mortality.

Genetic polymorphisms of innate and adaptive immunity as predictors of outcome in critically ill patients

Sepsis and septic shock frequently cause the admission or complicate the clinical course of critically ill patients admitted in the intensive care units (ICU). Genetic variations disrupting the immune sensing of infectious organisms, could affect the ability of the immune system to respond to infection, and may influence both the genetic predisposition to infection and the diversity of the clinical presentation of sepsis. The aim of this study was to uncover possible associations between common functional immune gene polymorphisms (of both innate and adaptive immunity) and ICU-acquired sepsis and mortality. The TLR4-D299G (rs4986790), TLR4-T399I (rs4986791), C2-c.841_849+19del28 (rs9332736), TACI-C104R (rs34557412), BAFFR-P21R (rs77874543), and BAFFR-H159Y (rs61756766) polymorphisms were detected in a cohort of 215 critically ill patients, admitted in an 8-bed medical/surgical ICU. Interestingly, TLR4-D299G, TLR4-T399I and BAFFR-P21R carriage was associated with a lower risk of ICU-acquired sepsis. This association applied particularly in medical patients, while in trauma and surgical patients no significant associations were observed. Moreover, carriers of TACI-C104R displayed an undiagnosed mild to moderate hypogammaglobulinemia along with a significantly lower survival rate in the ICU, although lethal events were not attributed to sepsis. These findings further elucidate the role that host immune genetic variations may play in the susceptibility to ICU-acquired sepsis and ICU mortality.

Using data-driven rules to predict mortality in severe community acquired pneumonia

Prediction of patient-centered outcomes in hospitals is useful for performance benchmarking, resource allocation, and guidance regarding active treatment and withdrawal of care. Yet, their use by clinicians is limited by the complexity of available tools and amount of data required. We propose to use Disjunctive Normal Forms as a novel approach to predict hospital and 90-day mortality from instance-based patient data, comprising demographic, genetic, and physiologic information in a large cohort of patients admitted with severe community acquired pneumonia. We develop two algorithms to efficiently learn Disjunctive Normal Forms, which yield easy-to-interpret rules that explicitly map data to the outcome of interest. Disjunctive Normal Forms achieve higher prediction performance quality compared to a set of state-of-the-art machine learning models, and unveils insights unavailable with standard methods. Disjunctive Normal Forms constitute an intuitive set of prediction rules that could be easily implemented to predict outcomes and guide criteria-based clinical decision making and clinical trial execution, and thus of greater practical usefulness than currently available prediction tools. The Java implementation of the tool JavaDNF will be publicly available.

Contact-free monitoring of circulation and perfusion dynamics based on the analysis of thermal imagery

Acute circulatory disorders are commonly associated with systemic inflammatory response (SIRS) and sepsis. During sepsis, microcirculatory perfusion is compromised leading to tissue hypoperfusion and potentially to multiple organ dysfunction. In the present study, acute lung injury (ALI), one of the major causes leading to SIRS and sepsis, was experimentally induced in six female pigs. To investigate the progress of body temperature distribution, measurements with a long-wave infrared camera were carried out. Temperature centralization was evidenced during ALI owing to impairments of peripheral perfusion. In addition, statistical analysis demonstrated strong correlations between (a) standard deviation of the skin temperature distribution (SD) and shock index (SI) (p<0.0005), (b) SD and mean arterial pressure (MAP) (p<0.0005), (c) ΔT/Δx and SI (p<0.0005), as well as between (d) ΔT/Δx and MAP (p<0.0005). For clarification purposes, ΔT/Δx is a parameter implemented to quantify the spatial temperature gradient. This pioneering study created promising results. It demonstrated the capacity of infrared thermography as well as of the indexes, SD and ΔT/Δx, to detect impairments in both circulation and tissue perfusion.

Has mortality from sepsis improved and what to expect from new treatment modalities: review of current insights

BACKGROUND

The incidence of sepsis is increasing continuously, making mortality rate reduction through improved intensive care unit (ICU) care and new treatment modalities a pressing issue. This study aimed to provide insight into the effects of modern ICU care on mortality trends from severe sepsis and to provide a quantitative review of the relative effectiveness of new treatment modalities in reducing deaths.

METHODS

Mortality data from severe sepsis were extracted from the control arms of several large randomized trials of sepsis treatment published within the last two decades. The effectiveness of recent treatment strategies was expressed as the number of patients it is necessary to treat by that method to save one life (number needed to treat: NNT).

RESULTS

Death from severe sepsis showed a decline from 44% to 35% between 1990 and 2000. The two most effective strategies in critically ill patients are early appropriate antibiotics (NNT 3; 95% confidence interval [CI] 2, 4) and early goal-directed therapy (NNT 6; 95% CI 4, 24). Infusion of recombinant human activated protein C is the most effective anticoagulant therapy (NNT 15; 95% CI 10, 27). Intensive insulin therapy is only moderately effective (NNT 27; 95% CI 15, 124).

CONCLUSIONS

The mortality rate from severe sepsis has decreased significantly with modernization of ICU care. New therapeutic strategies may reduce further the mortality rate. However, focused implementation of these new strategies in accordance with their relative effectiveness is needed before we can expect to see their true effect on mortality rates.

Tumor necrosis factor alpha -C850T polymorphism is significantly associated with endometriosis in Asian Indian women

OBJECTIVE

To establish the association of tumor necrosis factor alpha (TNFA) promoter C850T polymorphism in Asian Indian women with endometriosis.

DESIGN

Case control study, from multiple gynecological centers from Hyderabad, a cosmopolitan city in southern India. The study included 245 women who comprised 110 surgically confirmed cases of endometriosis, 50 ultrasonographically confirmed cases of fibroid tumors, and 85 healthy female volunteers.

SETTING

Academic hospital.

PATIENT(S)

The cases were 245 women, 160 patients and 85 controls.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Tumor necrosis factor alpha -C850T polymorphism may be used as a molecular marker for endometriosis in our population.

RESULT(S)

In this study we have demonstrated an association between TNFA -C850T polymorphism and endometriosis. The T allele is significantly associated with endometriosis when compared to women with fibroids as well as healthy controls. Our data imply that the T allele is associated with endometriosis (OR = 1.9594: 95% CI, 1.3833-2.7753; in our population. The TT genotype increases the risk of endometriosis by fourfold (4.5542: 95% CI, 2.0388-10.1701.

CONCLUSION(S)

This study suggests that -C850T TNFA gene polymorphism could be used as a relevant molecular marker to identify women with risk of developing endometriosis in our population.

Adiponectin deficiency is associated with severe polymicrobial sepsis, high inflammatory cytokine levels, and high mortality

BACKGROUND

Adiponectin, a key substance in metabolic syndrome, is known to have anti-inflammatory properties. The relationship between adiponectin and sepsis in vivo is unclear. In this study, the possible involvement of adiponectin in polymicrobial sepsis was investigated using adiponectin-knockout (APN-KO) mice that underwent cecal ligation and puncture (CLP) and received the peroxisome proliferator-activated receptor gamma (PPAR-gamma) that increases the plasma adiponectin concentration.

METHODS

APN-KO and wild-type (WT) mice underwent either CLP or a sham operation. The plasma adiponectin, endotoxin, tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) levels were determined before and at 2, 4, 6, 8, 12, 16, and 24 hours after the procedures, and the survival rates were compared. Mice were injected with rosiglitazone, a selective PPAR-gamma agonist, and compared survival rates after CLP with those without rosiglitazone.

RESULTS

After CLP, APN-KO mice had a significantly higher mortality than WT mice. The plasma endotoxin, TNF-alpha, and IL-6 levels in APN-KO mice were significantly higher than those in WT mice 24 hours after CLP. Within 4 hours after CLP, the plasma adiponectin level in WT mice decreased to half of the initial levels. Pre-CLP treatment with PPAR-gamma was shown to increase the plasma adiponectin level and to improve significantly mortality of WT mice during sepsis; mortality among APN-KO mice did not improve.

CONCLUSION

These results suggest that adiponectin deficiency may cause the high mortality and the high inflammatory cytokine levels in mice with polymicrobial sepsis.

[Diagnostic value of assay of brain natriuretic peptide in patients with sepsis of blood-stasis syndrome]

OBJECTIVE

To explore the diagnostic value of brain natriuretic peptide (BNP) level in patients with sepsis of blood-stasis syndrome.

METHODS

The prospective method of clinical diagnostic test and evaluation principles of diagnostic test were applied. One hundred and seventy-four patients with sepsis were divided into two groups: blood-stasis syndrome group and non blood-stasis syndrome group. The levels of serum BNP in two groups were detected.

RESULTS

The level of BNP in sepsis patients was related to blood-stasis syndrome (P<0.01). BNP cut-off level was 150 ng/L, sensitivity was 85.3%, specificity was 81%, the maximum value of Youden index was 0.663, and the area under the receiver operating characteristic curve (ROC) value was (0.886+/-0.025).

CONCLUSION

BNP can be used as an objective index of blood-stasis syndrome diagnosis for sepsis, and BNP with boundary value of 150 ng/L is an optimal biological index.

Review: variability of host-pathogen interaction

The course of every infection is different. The same pathogen can lead to subclinical, mild, severe or lethal infections in individuals. But is this just chance or determined by individual differences--on the side of the host as well as on the side of the pathogen? If so, we might need to consider these variations for treatment decisions. Indeed, we now understand that genetic polymorphisms and health status represent inborn and acquired risk factors. Similarly, pathogens impress with an increasing number of already identified virulence factors and host response modifiers. The emerging, more complex, view of the factors determining course and outcome of infections promises to enable more tailored and thus, hopefully, more effective treatment decisions.

Protein C -1641A/-1654C haplotype is associated with organ dysfunction and the fatal outcome of severe sepsis in Chinese Han population

Activation of protein C plays an important role in modulating coagulation as well as inflammation during severe sepsis. The baseline of activated protein C level in patients with severe sepsis showed interindividual variability between survivors and nonsurvivors, and the decreased level of protein C correlated with organ dysfunction and poor outcome. However, there are limited data concerning the genetic predisposition of individuals carrying two functional polymorphisms -1641A>G and -1654C>T within protein C gene to sepsis. Here we investigated the impact of these two variations on the development of severe sepsis in 240 patients with severe sepsis and 323 healthy controls using direct sequencing. After Bonferroni correction for multiple comparisons, -1641A/-1654C haplotype was significantly associated with the fatal outcome of severe sepsis (P = 0.008, OR 1.739, 95% CI 1.165-2.595), which was confirmed by multiple logistic regression analysis (P = 0.024, OR 2.090, 95% CI 1.101-3.967). Compared to patients without carrying -1641A/-1654C haplotype, the -1641A/-1654C haplotype carriers showed higher SOFAmax scores (10.3 +/- 5.2 vs. 9.0 +/- 4.5; P = 0.014) and more hepatic dysfunction (P = 0.004, OR 2.270, 95% CI 1.312-3.930). These findings suggest that protein C haplotype -1641A/-1654C is associated with organ dysfunction and is an independent risk factor for the fatal outcome of severe sepsis in Chinese Han population.

Sepsis: from bench to bedside

Sepsis is a syndrome related to severe infections. It is defined as the systemic host response to microorganisms in previously sterile tissues and is characterized by end-organ dysfunction away from the primary site of infection. The normal host response to infection is complex and aims to identify and control pathogen invasion, as well as to start immediate tissue repair. Both the cellular and humoral immune systems are activated, giving rise to both anti-inflammatory and proinflammatory responses. The chain of events that leads to sepsis is derived from the exacerbation of these mechanisms, promoting massive liberation of mediators and the progression of multiple organ dysfunction. Despite increasing knowledge about the pathophysiological pathways and processes involved in sepsis, morbidity and mortality remain unacceptably high. A large number of immunomodulatory agents have been studied in experimental and clinical settings in an attempt to find an efficacious anti-inflammatory drug that reduces mortality. Even though preclinical results had been promising, the vast majority of these trials actually showed little success in reducing the overwhelmingly high mortality rate of septic shock patients as compared with that of other critically ill intensive care unit patients. Clinical management usually begins with prompt recognition, determination of the probable infection site, early administration of antibiotics, and resuscitation protocols based on "early-goal" directed therapy. In this review, we address the research efforts that have been targeting risk factor identification, including genetics, pathophysiological mechanisms and strategies to recognize and treat these patients as early as possible.

Sepsis

Sepsis results from the host response to infection. While a localized and controlled inflammatory reaction helps to control infection, a dysregulated response may lead to multiple organ failure and determines the course and prognosis of the septic patient. Despite intensive care, mortality remains as high as 54% for severe sepsis and septic shock. As the mechanisms are becoming better defined, interventions aiming to interfere with the host response have been undertaken, largely with disappointing results. Thus, many evidence-based recommendations suggest waiving of resource-consuming interventions. Nevertheless, several seminal studies have indicated that early and systematic supportive therapy according to pathophysiological principles, most notably early goal-directed therapy, low-dose hydrocortisone and activated protein C, can disrupt dysfunctional cascades and can favourably influence the course of the disease. In parallel, efforts to better define nationwide epidemiology and treatment habits for severe sepsis by the German competence network "SepNet" indicate that therapy of severe sepsis is generally in poor compliance with guidelines, while the personal perception of physicians in charge would suggest high rates of adherence. Thus, strategies of change management, such as implementation of sepsis bundles are warranted to achieve a better standard of care toward the aim of the "surviving sepsis campaign", i.e. a reduction of mortality by 25% within the next 5 years.

Management of sepsis in neutropenia: guidelines of the infectious diseases working party (AGIHO) of the German Society of Hematology and Oncology (DGHO)

These guidelines from the infectious diseases working party (AGIHO) of the German Society of Hematology and Oncology (DGHO) give recommendations for the management of adults with neutropenia and the diagnosis of sepsis. The guidelines are written for clinicians and focus on pathophysiology, diagnosis, and treatment of sepsis. The manuscript contains evidence-based recommendations for the assessment of the quality and strength of the data.

Interleukin-10-1082 promoter polymorphism in association with cytokine production and sepsis susceptibility

OBJECTIVE

To investigate the -1082 (A/G) polymorphism in the promoter of the IL-10 gene in terms of IL-10 production from stimulated peripheral blood mononuclear cells (PBMC) and to evaluate the relationship of this polymorphism with susceptibility to severe sepsis and the outcome of the disease.

DESIGN

Case-control study.

SETTING

Research laboratory of Molecular Biology and Immunology and University Hospital ICU, Faculty of Medicine, Trakia University.

PATIENTS

A total of 53 healthy volunteers and 33 patients in ICU meeting the criteria for severe sepsis were included.

MEASUREMENTS AND RESULTS

The amplification refractory mutation system PCR was used for IL-10-1082 polymorphism detection. Isolated PBMC were stimulated with either C3-binding glycoprotein (C3bgp), lipopolysaccharide (LPS), phytohemagglutinin (PHA),or pokeweed mitogen (PWM). IL-10 production was measured in culture supernatants. The AA genotype was associated with lower IL-10 production in LPS-, PHA- or PWM-stimulated healthy PBMC. Patients with severe sepsis had significant elevation of A allele, compared with healthy controls (74.2% vs 52.8%; p=0.0062). Carriage of at least one copy of IL-10-1082 G allele in sepsis patients and in healthy controls resulted in a statistically significant increase in IL-10 production from stimulated PBMC. Surviving sepsis patients had a significant decrease of IL-10-1082 allele G frequency, compared with controls (17% vs 47.2%; p=0.012). An association between increased IL-10 production and poor outcome from sepsis was observed.

CONCLUSION

The A allele of the -1082 polymorphism in the interleukin-10 gene promoter is associated with sepsis susceptibility, whereas G allele is associated with higher stimulated interleukin-10 production and increased mortality in severe sepsis.

Genetic variability in the immune-inflammatory response after major burn injury

Thermal injury induces immune dysfunction and alters numerous physiological parameters. Studies have proposed that genetics influence the outcome after traumatic injury and/or sepsis, however, the contribution of genetics to the immune-inflammatory response postburn has not been investigated. In this study, mice of three distinct genetic backgrounds (C57BL/6NCrlBR, BALB/cAnNCrlBR, and 129S6/SvEvTac) were subjected to thermal injury or a sham procedure, and 3 days later, blood and splenic immune cells (splenocytes and macrophages) were isolated for analysis. Splenocytes from the C57BL/6NCrlBR strain displayed suppressed splenic T cell proliferation postinjury, whereas the other strains were unaffected. Burn injury also induced a shift toward a Th2-type T-cell response (suppressed IFN-gamma production) in the C57BL/6NCrlBR strain, but not in the other strains. Macrophages from C57BL/6NCrlBR and 129S6/SvEvTac mice were highly proinflammatory with elevated productive capacity for TNF-alpha and nitric oxide, whereas no such changes were observed in macrophages for BALB/cNCrlBR mice. C57BL/6NCRLBR macrophages produced increased IL-10 levels postburn, and BALB/cNCrlBR macrophages had suppressed IL-10 production postinjury. No differences in fasting blood glucose and insulin were observed after thermal injury. However, significant postburn weight loss was observed in the BALB/cNCrlBR and 129S6/SvEvTac strains, but not in the C57BL/6NCrlBR strain. In summary, these findings support the concept that the immune-inflammatory response postburn is influenced by genetic make-up. Further elucidation of the influence of genetics under such conditions is likely to contribute to the improvement in existing, and development of new, therapeutic regimes for burn patients.

In silico design of clinical trials: A method coming of age

OBJECTIVE

To determine the feasibility and potential usefulness of mathematical models in evaluating immunomodulatory strategies in clinical trials of severe sepsis.

DESIGN

Mathematical modeling of immunomodulation in simulated patients.

SETTING

Computer laboratory.

MEASUREMENTS AND MAIN RESULTS

We introduce and evaluate the concept of conducting a randomized clinical trial in silico based on simulated patients generated from a mechanistic mathematical model of bacterial infection, the acute inflammatory response, global tissue dysfunction, and a therapeutic intervention. Trial populations are constructed to reflect heterogeneity in bacterial load and virulence as well as propensity to mount and modulate an inflammatory response. We constructed a cohort of 1,000 trial patients submitted to therapy with one of three different doses of a neutralizing antibody directed against tumor necrosis factor (anti-TNF) for 6, 24, or 48 hrs. We present cytokine profiles over time and expected outcome for each cohort. We identify subgroups with high propensity for being helped or harmed by the proposed intervention and identify early serum markers for each of those subgroups. The mathematical simulation confirms the inability of simple markers to predict outcome of sepsis. The simulation clearly separates cases with favorable and unfavorable outcome on the basis of global tissue dysfunction. Control survival was 62.9% at 1 wk. Depending on dose and duration of treatment, survival ranged from 57.1% to 80.8%. Higher doses of anti-TNF, although effective, also result in considerable harm to patients. A statistical analysis based on a simulated cohort identified markers of favorable or adverse response to anti-TNF treatment.

CONCLUSIONS

A mathematical simulation of anti-TNF therapy identified clear windows of opportunity for this intervention as well as populations that can be harmed by anti-TNF therapy. The construction of an in silico clinical trial could provide profound insight into the design of clinical trials of immunomodulatory therapies, ranging from optimal patient selection to individualized dosage and duration of proposed therapeutic interventions.

The role of molecular genetics in the pathogenesis and diagnosis of neonatal sepsis

Polymorphisms within genes encoding endogenous mediators of inflammation are good candidates for the individual differences in systemic inflammatory responses of neonates to infection. Ina similar manner, polymorphisms in the genes encoding drug metabolizing enzymes, drug transporters, and drug receptors can influence a neonate's risk of an adverse drug reaction or can alter the efficacy of drug treatment. Additionally, molecular tools are proving valuable in the diagnosis of neonatal infection. This article gives an overview of the genetic susceptibility to sepsis, discusses the use of molecular genetics in diagnostic tests for infection, and reviews the potential for more effective and specific therapies for sepsis based on genetic variability.

Molecular diagnostics of injury and repair responses in critical illness: what is the future of "monitoring" in the intensive care unit?

OBJECTIVE

To identify potential future means of monitoring injury and repair in critical illness.

DESIGN

Review of the literature.

RESULTS

Critically ill patients are monitored extensively and intensively by such means as hemodynamics, laboratory values, and radiologic studies. In general, however, the goal of monitoring has been to measure the degree of injury and to prevent further injury, rather than to measure repair. Measures of repair have been limited to phenotypic end points such as return of organ function, as measured by blood chemistry. In this article, I examine how it may be possible in the future to monitor the progress of repair using genomic and proteomic biomarkers. These types of monitors would enable clinicians to control the healing environment using real time, rapid biomarkers, and sophisticated techniques to target therapy to the patient's current inflammatory state, taking into account the genetic makeup of the patient and his or her likely response to a given drug.

CONCLUSIONS

The rapidly evolving sciences of genomics, proteomics, computational biology, and complex system theory can be used a) to model critical illness; b) to model adaptive and maladaptive responses to critical illness; c) to tailor treatments to create an ideal inflammatory environment for repair and regeneration, taking into account the individual genetic contribution; and d) to monitor the progress of repair. The major obstacles to reaching these goals are technological, and experience suggests that they will be overcome.

The immunopathogenesis of sepsis

Sepsis is a condition that results from a harmful or damaging host response to infection. Many of the components of the innate immune response that are normally concerned with host defences against infection can, under some circumstances, cause cell and tissue damage and hence multiple organ failure, the clinical hallmark of sepsis. Because of the high mortality of sepsis in the face of standard treatment, many efforts have been made to improve understanding of the dysregulation of the host response in sepsis. As a result, much has been learnt of the basic principles governing bacterial-host interactions, and new opportunities for therapeutic intervention have been revealed.

Interferon-gamma gene polymorphisms and the development of sepsis in patients with trauma

BACKGROUND

The outcome of patients with trauma does not always correlate with injury severity or premorbid health status. This study evaluates the relationship between polymorphisms in the first intron of the interferon-gamma gene and the development of sepsis after trauma.

METHODS

DNA was extracted from peripheral leukocytes of patients with trauma and an injury severity score of 16 or greater. Data collected included demographics, injury mechanism, injuries sustained, development of sepsis, and outcome. A previously identified cytosine/adenine repeated polymorphism was amplified, alleles/genotypes identified, and the results correlated with patient outcome.

RESULTS

Sixty-one patients were evaluated. Thirty patients (49%) became septic. The injury severity score, race, age, and gender distribution was similar for both the septic and nonseptic groups. Six alleles and 10 genotypes were identified. Alleles C (34%) and D (52%) were the most common. Patients who were septic had a 62% chance of having a D allele (P =.06), whereas they had only a 29% chance of having a C allele. Homozygotes for allele D (DD) were the most likely to become septic (65%).

CONCLUSIONS

Homozygotes for the D allele (DD) of the interferon-gamma gene have an increased chance of developing sepsis after traumatic injury compared with other allelic combinations. This supports the hypothesis that genetic composition plays a role in patient outcome.

Infection in the chronically critically ill: unique risk profile in a newly defined population

Although CCI is defined as prolonged ventilatory failure with tracheotomy stemming from preceding critical illness, the contention that multisystem debilities impact on most CCI patients' care and recovery is a central thesis of this volume. Perhaps reflecting the combined debilities inherent in CCI, infectious complications take their toll in morbidity, mortality, and persistent ventilatory insufficiency. Enhanced susceptibility to infection results from a potent admixture of barrier breakdown, exposure to virulent and resistant nosocomial pathogens, and postulated "immune exhaustion" that stems from the combined impact of comorbidities and the sequellae of critical illness. Strategies to improve outcome in CCI-related infection include standard measures of support especially nutrition, reducing environmental inoculum through pulmonary hygiene measures, skin care, and limiting barrier breaches, and appropriate antimicrobials directed at likely pathogens. Future stratification of patient risk on the basis of immune phenotype or genotype and potential immunomodulatory prophylaxis may be around the corner, as new prospects in the pharmaceutical armamentarium are presently undergoing testing.

Megalin and cubilin: multifunctional endocytic receptors

The ability to take up substances from the surrounding environment not only provides cells with vital nutrients, but also enables the selective transport of substances from one compartment to another. Megalin and cubilin are two structurally different endocytic receptors that interact to serve such functions. Evidence has accumulated in recent years to indicate that these receptors have important functions in both normal physiology and pathology.

Differential expression and tissue compartmentalization of the inflammatory response following thermal injury

Studies have shown that both animal tissue-fixed immune cells and human peripheral blood mononuclear cell (PBMC) functions are altered after burn injury. Additional studies suggest that the burn injury-induced alterations in these divergent cell populations from different species are similar. It remains unknown, however, whether the observed changes in animal tissue-fixed immune cell function following thermal injury also occurs to a similar extent in the PBMC population. The aim of our study was to compare PBMC and tissue-fixed immune cell functions from the same animal using a murine burn model. At 7 days post-burn, mice were more susceptible to sepsis and delayed type hypersensitivity responses were suppressed. Splenocytes isolated from injured mice displayed suppressed proliferation and increased IL-10 production. In contrast, PBMC from injured mice displayed suppressed proliferation, IL-2 and IFN-gamma production. Splenic macrophage nitric oxide, PGE(2), TNF-alpha, IL-6 and IL-10 production was enhanced post-burn and IL-12 production was suppressed. PBMC from such animals displayed enhanced PGE(2) production and suppressed IL-6 and IL-12 production. These results indicate that while an immunosuppressive Th(2) phenotype (increased IL-10 and/or suppressed IL-2, IFN-gamma) was induced in both the splenic and PBMC compartments post-injury, differential expression and dimorphism in the response also exists. Thus, the assessment of only PBMC function in burn patients may not accurately reflect the patient's actual immune status at the tissue level.