Role of interleukin-10 in monocyte hyporesponsiveness associated with septic shock

Research Progress on the Mechanism and Management of Septic Cardiomyopathy: A Comprehensive Review

Sepsis is defined as a kind of life-threatening organ dysfunction due to a dysregulated host immune response to infection and is a leading cause of mortality in the intensive care unit. Sepsis-induced myocardial dysfunction, also called septic cardiomyopathy, is a common and serious complication in patients with sepsis, which may indicate a bad prognosis. Although efforts have been made to uncover the pathophysiology of septic cardiomyopathy, a number of uncertainties remain. This article sought to review available literature to summarize the existing knowledge on current diagnostic tools and biomarkers, pathogenesis, and treatments for septic cardiomyopathy.

Identifying Prokineticin2 as a Novel Immunomodulatory Factor in Diagnosis and Treatment of Sepsis

OBJECTIVES

Sepsis remains a highly lethal disease, whereas the precise reasons for death remain poorly understood. Prokineticin2 is a secreted protein that regulates diverse biological processes. Whether prokineticin2 is beneficial or deleterious to sepsis and the underlying mechanisms remain unknown.

DESIGN

Prospective randomized animal investigation and in vitro studies.

SETTING

Research laboratory at a medical university hospital.

SUBJECTS

Prokineticin2 deficiency and wild-type C57BL/6 mice were used for in vivo studies; sepsis patients by Sepsis-3 definitions, patient controls, and healthy controls were used to obtain blood for in vitro studies.

INTERVENTIONS

Prokineticin2 concentrations were measured and analyzed in human septic patients, patient controls, and healthy individuals. The effects of prokineticin2 on sepsis-related survival, bacterial burden, organ injury, and inflammation were assessed in an animal model of cecal ligation and puncture-induced polymicrobial sepsis. In vitro cell models were also used to study the role of prokineticin2 on antibacterial response of macrophages.

MEASUREMENTS AND MAIN RESULTS

Prokineticin2 concentration is dramatically decreased in the patients with sepsis and septic shock compared with those of patient controls and healthy controls. Furthermore, the prokineticin2 concentration in these patients died of sepsis or septic shock is significantly lower than those survival patients with sepsis or septic shock, indicating the potential value of prokineticin2 in the diagnosis of sepsis and septic shock, as well as the potential value in predicting mortality in adult patients with sepsis and septic shock. In animal model, recombinant prokineticin2 administration protected against sepsis-related deaths in both heterozygous prokineticin2 deficient mice and wild-type mice and alleviated sepsis-induced multiple organ damage. In in vitro cell models, prokineticin2 enhanced the phagocytic and bactericidal functions of macrophage through signal transducers and activators of transcription 3 pathway which could be abolished by signal transducers and activators of transcription 3 inhibitors S3I-201. Depletion of macrophages reversed prokineticin2-mediated protection against polymicrobial sepsis.

CONCLUSIONS

This study elucidated a previously unrecognized role of prokineticin2 in clinical diagnosis and treatment of sepsis. The proof-of-concept study determined a central role of prokineticin2 in alleviating sepsis-induced death by regulation of macrophage function, which presents a new strategy for sepsis immunotherapy.

Identification of the robust predictor for sepsis based on clustering analysis

Sepsis is a life-threatening disorder with high incidence and mortality rate. However, the early detection of sepsis is challenging due to lack of specific marker and various etiology. This study aimed to identify robust risk factors for sepsis via cluster analysis. The integrative task of the automatic platform (i.e., electronic medical record) and the expert domain was performed to compile clinical and medical information for 2,490 sepsis patients and 16,916 health check-up participants. The subjects were categorized into 3 and 4 groups based on seven clinical and laboratory markers (Age, WBC, NLR, Hb, PLT, DNI, and MPXI) by K-means clustering. Logistic regression model was performed for all subjects including healthy control and sepsis patients, and cluster-specific cases, separately, to identify sepsis-related features. White blood cell (WBC), well-known parameter for sepsis, exhibited the insignificant association with the sepsis status in old age clusters (K3C3 and K4C3). Besides, NLR and DNI were the robust predictors in all subjects as well as three or four cluster-specific subjects including K3C3 or K4C3. We implemented the cluster-analysis for real-world hospital data to identify the robust predictors for sepsis, which could contribute to screen likely overlooked and potential sepsis patients (e.g., sepsis patients without WBC count elevation).

Monocyte distribution width (MDW): a useful biomarker to improve sepsis management in Emergency Department

OBJECTIVES

Sepsis is a time-dependent and life-threating condition. Despite several biomarkers are available, none of them is completely reliable for the diagnosis. This study aimed to evaluate the diagnostic utility of monocyte distribution width (MDW) to early detect sepsis in adult patients admitted in the Emergency Department (ED) with a five part differential analysis as part of the standard clinical practice.

METHODS

A prospective cohort study was conducted on 985 patients aged from 18 to 96 and included in the study between November 2019 and December 2019. Enrolled subjects were classified into four groups based on sepsis-2 diagnostic criteria: control, Systemic Inflammatory Response Syndrome (SIRS), infection and sepsis. The hematology analyzer DxH 900 (Beckman Coulter Inc.) provides the new reportable parameter MDW, included in the leukocyte 5 part differential analysis, cleared by Food and Drug administration (FDA) and European Community In-Vitro-Diagnostic Medical Device (CE IVD) marked as early sepsis indicator (ESId).

RESULTS

MDW was able to differentiate the sepsis group from all other groups with Area Under the Curve (AUC) of 0.849, sensitivity of 87.3% and specificity of 71.7% at cut-off of 20.1. MDW in combination with white blood cell (WBC) improves the performance for sepsis detection with a sensitivity increased up to 96.8% when at least one of the two biomarkers are abnormal, and a specificity increased up to 94.6% when both biomarkers are abnormal.

CONCLUSIONS

MDW can predict sepsis increasing the clinical value of Leukocyte 5 Part Differential analysis and supporting the clinical decision making in sepsis management at the admission to the ED.

Role of Specialized Pro-Resolving Mediators in Modifying Host Defense and Decreasing Bacterial Virulence

Bacterial infection activates the innate immune system as part of the host’s defense against invading pathogens. Host response to bacterial pathogens includes leukocyte activation, inflammatory mediator release, phagocytosis, and killing of bacteria. An appropriate host response requires resolution. The resolution phase involves attenuation of neutrophil migration, neutrophil apoptosis, macrophage recruitment, increased phagocytosis, efferocytosis of apoptotic neutrophils, and tissue repair. Specialized Pro-resolving Mediators (SPMs) are bioactive fatty acids that were shown to be highly effective in promoting resolution of infectious inflammation and survival in several models of infection. In this review, we provide insight into the role of SPMs in active host defense mechanisms for bacterial clearance including a new mechanism of action in which an SPM acts directly to reduce bacterial virulence.

Characterization of Circulating IL-10-Producing Cells in Septic Shock Patients: A Proof of Concept Study

Sepsis is a worldwide health priority characterized by the occurrence of severe immunosuppression associated with increased risk of death and secondary infections. Interleukin 10 (IL-10) is a potent immunosuppressive cytokine which plasma concentration is increased in septic patients in association with deleterious outcomes. Despite studies evaluating IL-10 production in specific subpopulations of purified cells, the concomitant description of IL-10 production in monocytes and lymphocytes in septic patients' whole blood has never been performed. In this pilot study, we characterized IL-10 producing leukocytes in septic shock patients through whole blood intracellular staining by flow cytometry. Twelve adult septic shock patients and 9 healthy volunteers were included. Intracellular tumor necrosis factor-α (TNFα) and IL-10 productions after lipopolysaccharide stimulation by monocytes and IL-10 production after PMA/Ionomycine stimulation by lymphocytes were evaluated. Standard immunomonitoring (HLA-DR expression on monocytes, CD4+ T lymphocyte count) of patients was also performed. TNFα expression by stimulated monocytes was reduced in patients compared with controls while IL-10 production was increased. This was correlated with a reduced monocyte HLA-DR expression. B cells, CD4+, and CD4- T lymphocytes were the three circulating IL-10 producing lymphocyte subsets in both patients and controls. No difference in IL-10 production between patients and controls was observed for B and CD4- T cells. However, IL-10 production by CD4+ T lymphocytes significantly increased in patients in parallel with reduced CD4+ T cells number. Parameters reflecting altered monocyte (increased IL-10 production, decreased HLA-DR expression and decreased TNFα synthesis) and CD4+ T lymphocyte (increased IL-10 production, decreased circulating number) responses were correlated. Using a novel technique for intracellular cytokine measurement in whole blood, our results identify monocytes and CD4+ T cells as the main IL-10 producers in septic patients' whole blood and illustrate the development of a global immunosuppressive profile in septic shock. Overall, these preliminary results add to our understanding of the global increase in IL-10 production induced by septic shock. Further research is mandatory to determine the pathophysiological mechanisms leading to such increased IL-10 production in monocytes and CD4+ T cells.

Cytokines and their relationship with the severity and prognosis of coronavirus disease 2019 (COVID-19): a retrospective cohort study

OBJECTIVE

To delineate the characteristics and clinical significance of plasma inflammatory cytokines altered in COVID-19.

DESIGN

Retrospective, single-centre cohort study.

SETTING

Tongji Hospital in Wuhan, China.

PARTICIPANTS

Among a cohort of 308 patients with a diagnosis of COVID-19, 138 patients died while 170 patients recovered and were discharged from the hospital. The data were collected until 27 February 2020.

PRIMARY AND SECONDARY OUTCOME MEASURES

Clinical characteristics and laboratory findings were obtained from electronic medical records using data collection forms.

RESULTS

The percentage of patients with elevated interleukin 2 receptor (IL-2R), IL-6, IL-8, IL-10 and tumour necrosis factor (TNF) increased with severity of disease (p<0.0001 for all). IL-2R (p<0.0001), IL-6 (p<0.0001), IL-8 (p=0.0001), IL-10 (p<0.0001) and TNF (p<0.0001) were also twofold to 20-fold higher in patients who died compared with those who recovered. Also, IL-6 and IL-10 increased in both the progressive patient groups: moderate (p=0.0026) and severe (p<0.0001). In multivariate analysis, higher levels of IL-2R (OR 1.001, 95% CI 1.000 to 1.002, p=0.031) and IL-6 (OR 1.013, 95% CI 1.003 to 1.024, p=0.015) on admission were associated with increasing odds of in-hospital death, independent of other covariates, including severity of disease and lymphocyte count.

CONCLUSION

Increased proinflammatory and anti-inflammatory cytokines, including IL-2R, IL-6, IL-8, TNF and IL-10, showed an obvious association with both COVID-19 severity and in-hospital mortality. Thus, our study indicates that cytokines are valuable in predicting the severity of COVID-19 and helps in distinguishing critically ill patients from the less affected ones.

Altered cytokine levels and immune responses in patients with SARS-CoV-2 infection and related conditions

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a global pandemic in early 2020. The infection has been associated with a wide range of clinical symptoms. In the severely affected patients, it has caused dysregulation of immune responses including over-secretion of inflammatory cytokines and imbalances in the proportion of naïve helper T cells, memory helper T cells and regulatory T cells. Identification of the underlying mechanism of such aberrant function of immune system would help in the prediction of disease course and selection of susceptible patients for more intensive cares. In the current review, we summarize the results of studies which reported alterations in cytokine levels and immune cell functions in patients affected with SARS-CoV-2 and related viruses.

Sepsis-associated encephalopathy: a vicious cycle of immunosuppression

Sepsis-associated encephalopathy (SAE) is commonly complicated by septic conditions, and is responsible for increased mortality and poor outcomes in septic patients. Uncontrolled neuroinflammation and ischemic injury are major contributors to brain dysfunction, which arises from intractable immune malfunction and the collapse of neuroendocrine immune networks, such as the cholinergic anti-inflammatory pathway, hypothalamic-pituitary-adrenal axis, and sympathetic nervous system. Dysfunction in these neuromodulatory mechanisms compromised by SAE jeopardizes systemic immune responses, including those of neutrophils, macrophages/monocytes, dendritic cells, and T lymphocytes, which ultimately results in a vicious cycle between brain injury and a progressively aberrant immune response. Deep insight into the crosstalk between SAE and peripheral immunity is of great importance in extending the knowledge of the pathogenesis and development of sepsis-induced immunosuppression, as well as in exploring its effective remedies.

Inflammatory cytokines and organ dysfunction associate with the aberrant DNA methylome of monocytes in sepsis

BACKGROUND

Sepsis, a life-threatening organ dysfunction caused by a dysregulated systemic immune response to infection, associates with reduced responsiveness to subsequent infections. How such tolerance is acquired is not well understood but is known to involve epigenetic and transcriptional dysregulation.

METHODS

Bead arrays were used to compare global DNA methylation changes in patients with sepsis, non-infectious systemic inflammatory response syndrome, and healthy controls. Bioinformatic analyses were performed to dissect functional reprogramming and signaling pathways related to the acquisition of these specific DNA methylation alterations. Finally, in vitro experiments using human monocytes were performed to test the induction of similar DNA methylation reprogramming.

RESULTS

Here, we focused on DNA methylation changes associated with sepsis, given their potential role in stabilizing altered phenotypes. Tolerized monocytes from patients with sepsis display changes in their DNA methylomes with respect to those from healthy controls, affecting critical monocyte-related genes. DNA methylation profiles correlate with IL-10 and IL-6 levels, significantly increased in monocytes in sepsis, as well as with the Sequential Organ Failure Assessment score; the observed changes associate with TFs and pathways downstream to toll-like receptors and inflammatory cytokines. In fact, in vitro stimulation of toll-like receptors in monocytes results in similar gains and losses of methylation together with the acquisition of tolerance.

CONCLUSION

We have identified a DNA methylation signature associated with sepsis that is downstream to the response of monocytes to inflammatory signals associated with the acquisition of a tolerized phenotype and organic dysfunction.

Possible cytokine biomarkers in pediatric acute appendicitis

BACKGROUND

Diagnosis of acute appendicitis (AA) and decisions about its treatment remain among the most common dilemmas of pediatric surgical teams. Monitoring of immune response may be of importance for this purpose. Our aim was to measure and analyze serum and peritoneal fluid cytokines, in children who had undergone surgery for suspected AA.

METHODS

Prospective investigation of serum and peritoneal fluid cytokine values was performed in 127 consecutive patients. According to the pathohistological findings, patients were divided into three groups: normal/early, uncomplicated and complicated AA. Determination of cytokine concentrations for 20 different cytokines was done using a commercial flow cytometry kit: Human Inflammation 20 plex BMS 819.

RESULTS

Statistically significant differences in serum cytokine values between pathohistological groups were found for IP-10, MIP-1α and IL-10. Preoperative cut-off values of IP-10, MIP-1α and IL-10 between groups were obtained using ROC curve analysis. Positive correlations between serum and peritoneal concentrations were recorded for most of the analyzed cytokines.

CONCLUSION

IP-10, MIP-1α and IL-10 showed potential in assessment of AA in children. Confirmatory studies with a larger number of patients are required to prove reliability of these biomarkers.

New frontiers in precision medicine for sepsis-induced immunoparalysis

INTRODUCTION

In the last decade, the sepsis research field has shifted focus from targeting hyperinflammation to reversing sepsis-induced immunoparalysis. Sepsis-induced immunoparalysis is very heterogeneous: the magnitude and the nature of the underlying immune defects differ considerably between patients, but also within individuals over time. Therefore, a 'one-treatment-fits-all' strategy for sepsis-induced immunoparalysis is bound to fail, and an individualized 'precision medicine' approach is required. Such a strategy is nevertheless hampered by the unsuitability of the currently available markers to identify the many immune defects that can manifest in individual patients. Areas covered: We describe the currently available markers for sepsis-induced immunoparalysis and limitations pertaining to their use. Furthermore, future prospects and caveats are discussed, focusing on 'omics' approaches: genomics, transcriptomics, epigenomics, and metabolomics. Finally, we present a contemporary overview of adjuvant immunostimulatory therapies. Expert opinion: The integration of multiple omics techniques offers a systems biology approach which can yield biomarker profiles that accurately and comprehensively gauge the extent and nature of sepsis-induced immunoparalysis. We expect this development to be instrumental in facilitating precision medicine for sepsis-induced immunoparalysis, consisting of the application of targeted immunostimulatory therapies and follow-up measurements to monitor the response to treatment and to titrate or adjust medication.

Advances in the understanding and treatment of sepsis-induced immunosuppression

Sepsis is defined as a life-threatening organ dysfunction that is caused by a dysregulated host response to infection. Sepsis can induce acute kidney injury and multiple organ failures and represents the most common cause of death in the intensive care unit. Sepsis initiates a complex immune response that varies over time, with the concomitant occurrence of both pro-inflammatory and anti-inflammatory mechanisms. As a result, most patients with sepsis rapidly display signs of profound immunosuppression, which is associated with deleterious consequences. Scientific advances have highlighted the role of metabolic failure, epigenetic reprogramming, myeloid-derived suppressor cells, immature suppressive neutrophils and immune alterations in primary lymphoid organs (the thymus and bone marrow) in sepsis. An improved understanding of the mechanisms underlying this immunosuppression as well as of the similarities between sepsis-induced immunosuppression and immune defects in cancer or immunosenescence has led to novel therapeutic strategies aimed at stimulating immune function in patients with sepsis. Trials assessing the therapeutic benefit of IL-7, granulocyte-macrophage colony-stimulating factor (GM-CSF) and antibodies against programmed cell death protein 1 (PD1) and programmed cell death 1 ligand 1 (PDL1) for the treatment of sepsis are in progress. The reappraisal of sepsis pathophysiology has also resulted in a novel approach to the design of clinical trials evaluating sepsis treatments, based on an evaluation of the immune status and biomarker-based stratification of patients.

Host resistance to endotoxic shock requires the neuroendocrine regulation of group 1 innate lymphoid cells

Quatrini et al. demonstrate that neuroendocrine regulation of IFN-γ production by group 1 innate lymphoid cells (ILCs) is required to develop an IL-10–dependent resistance to endotoxin-induced septic shock, revealing a novel strategy of host protection from immunopathology.

Upon infection, the immune system produces inflammatory mediators important for pathogen clearance. However, inflammation can also have deleterious effect on the host and is tightly regulated. Immune system–derived cytokines stimulate the hypothalamic–pituitary–adrenal (HPA) axis, triggering endogenous glucocorticoid production. Through interaction with ubiquitously expressed glucocorticoid receptors (GRs), this steroid hormone has pleiotropic effects on many cell types. Using a genetic mouse model in which the gene encoding the GR is selectively deleted in NKp46⁺ innate lymphoid cells (ILCs), we demonstrated a major role for the HPA pathway in host resistance to endotoxin-induced septic shock. GR expression in group 1 ILCs is required to limit their IFN-γ production, thereby allowing the development of IL-10–dependent tolerance to endotoxin. These findings suggest that neuroendocrine axes are crucial for tolerization of the innate immune system to microbial endotoxin exposure through direct corticosterone-mediated effects on NKp46-expressing innate cells, revealing a novel strategy of host protection from immunopathology.

High Interleukin-10 Expression in Type 2 T Helper Cells in Septic Patients

Interleukin (IL)-10 response is associated with mortality in patients with sepsis. IL-10 is primarily produced by monocytes and type 2 T helper (Th2) cells. The aim of this study was to investigate differences in IL-10 production between monocytes and Th2 cells in patients with sepsis. Forty patients with sepsis and 35 healthy controls were enrolled. Cytokine expressions in peripheral blood mononuclear cells (PBMCs) were measured by flow cytometry. The IL-10 expression in the Th2 cells of the septic patients was higher than in the healthy controls, but the expression of IL-10 in the monocytes of the septic patients was lower than in the healthy controls. After regression analysis, IL-10 expression in Th2 cells was positively associated with sepsis, but IL-10 expression in monocytes was not associated with sepsis or shock. In conclusion, the production of IL-10 in Th2 cells was higher in the patients with sepsis.

Review: Molecular mechanisms of endotoxin tolerance

The phenomenon of endotoxin tolerance has been widely investigated, but to date, the molecular mechanisms of endotoxin tolerance remain to be resolved clearly. The discovery of the Toll-like receptor (TLR) family as the major receptors for lipopolysaccharide (LPS) and other bacterial products has prompted a resurgence of interest in endotoxin tolerance mechanisms. Changes of cell surface molecules, signaling proteins, pro-inflammatory and anti -inflammatory cytokines and other mediators have been examined. During tolerance expression of LPS-binding protein (LBP), CD14, myeloid differentiation protein-2 (MD-2) and TLR2 are unchanged or up-regulated, whereas TLR4 is transiently suppressed or unchanged. Proximal post-receptor signaling proteins that are altered in tolerance include augmented degradation of interleukin-1 receptor-associated kinase (IRAK), and decreased TLR4-myeloid differentiation factor 88 (MyD88) and IRAK-MyD88 association. Tolerance has also been shown to be associated with decreased Gi protein content and activity, decreased protein kinase C (PKC) activity, reduction in mitogen-activated protein kinase (MAP kinase) activity, and reduced activator protein-1 (AP-1) and nuclear factor kappa B (NF-κB) induced gene transactivation. However, not all signaling proteins and pathways are suppressed in tolerance and induction of specific anti-inflammatory proteins and signaling pathways may serve important counter inflammatory functions. The latter include induction of IRAK-M and suppressor of cytokine-signaling-1 (SOCS-1), phosphoinositide-3-kinase (PI3K) signaling, and increased or maintained expression of inhibitor-κB (IκB) isoforms. Also at the nuclear level, increase in the NFκB subunit p50 homodimer expression and increased activation of peroxisome-proliferatoractivated receptors-γ (PPARγ) have been linked to tolerance phenotype. Although there are species and cellular variations in manifestation of the LPS tolerant phenotype, it is clear that the tolerance phenomena have evolved as a complex orchestrated counter regulatory response to inflammation.

The Significance and Challenges of Monocyte Impairment: For the Ill Patient and the Surgeon

BACKGROUND

Trauma, major elective surgery, and overt sepsis can lead to a cascade of immunological change. A subset of these patients will have a degree of immune suppression that leads to hyporesponsive innate defenses, increasing the risk of infective co-morbidity and death. This article is an overview of monocyte impairment in the high-risk surgical patient. Specifically, our primary focus is on observations made pertaining to monocyte function and pathophysiological mechanisms underpinning this impairment. Clinical factors influencing monocyte function are also discussed.

METHODS

A Pubmed search was conducted to review aspects of monocyte impairment in the surgical patient. Search terms included "monocyte impairment," "immunoparalysis," and "endotoxin tolerance" cross-referenced against terms including "trauma," "major surgery," and "sepsis."

RESULTS

Findings revealed a broad variety of monocyte defects reported in surgical patients. They ranged from altered cytokine responses, particularly ex vivo TNF-α production, to impaired antigen presentation such as depressed HLA-DR expression. The latter is the most commonly described marker of secondary infection and death. Studies of underlying mechanisms have commonly utilized a model of endotoxin tolerance with in vitro monocytes, revealing a complex array of dysregulated pathways. For our purposes, endotoxin tolerance and monocyte impairment are sufficiently similar entities to permit further study as a single subject. In the high risk patient, microRNAs (also referred to as miRNA or miR) are emerging as potential biomarkers that may modify such pathways. Creation of a reliable impaired human monocyte model could be important to all such considerations.

CONCLUSION

Impairment of monocyte function continues to be predictive of nosocomial infection, multi-organ failure, and death in some surgical patients. However, the optimal marker that could identify a patient as high risk early enough, and whether it might guide potential therapy, still is yet to be proven.

Upregulated Expression of A20 on Monocytes is Associated With Increased Severity of Acute-on-Chronic Hepatitis B Liver Failure: A Case-Control Study

A20 expression is increased in various inflammatory diseases. However, the role of A20 in acute-on-chronic liver failure is unknown. This study was to evaluate A20 expression on monocytes and its associations with the severity of acute-on-chronic hepatitis B liver failure (ACHBLF). Thirty-seven patients with ACHBLF, 20 patients with chronic hepatitis B (CHB), and 15 healthy controls (HC) were enrolled in this case-control study. A20-positive monocytes were identified using flow cytometry. Serum levels of interleukin (IL)-10, IL-12p70, and TNF-α were determined using bead cytometry. A20 and IL-10 expressions were examined in THP-1 cells stimulated by lipopolysaccharide (LPS). The frequency of A20+ monocytes was significantly increased in patients with ACHBLF compared with HC (median [interquartile range, IQR]: 15.7 [22.8]% vs 2.5 [4.7]%, P < 0.001). Increased monocyte A20 expression was detected during the progression phase (including the mild/moderate and severe grades of ACHBLF) compared with patients in the recovery phase (both P < 0.05), and in the ACHBLF worsening group compared with patients in the improvement group (P < 0.001). LPS treatment upregulated A20 and IL-10 expressions in THP-1 cells. A20 expression on monocytes from patients with ACHBLF was positively correlated with total bilirubin (r = 0.60, P = 0.0001), direct bilirubin (r = 0.63, P < 0.0001), and MELD score (r = 0.43, P = 0.008), and inversely with prothrombin activity (r = -0.33, P = 0.046). IL-10 and TLR4 expression levels in monocytes, and serum levels of IL-10, IL-12p70, and TNF-α were increased in patients with ACHBLF compared with patients with CHB and HC. Increased A20 expression on monocytes was associated with the severity of ACHBLF.

Effects of antimicrobial prophylaxis and blood stream infections in patients with acute liver failure: a retrospective cohort study

BACKGROUND & AIMS

We investigated whether antimicrobial prophylaxis alters the incidence of bloodstream infection in patients with acute liver failure (ALF), and whether bloodstream infections affect overall mortality within 21 days after development of ALF.

METHODS

We performed a retrospective cohort analysis of 1551 patients with ALF enrolled by the US Acute Liver Failure Study Group from January 1998 through November 2009. We analyzed data on infections in the first 7 days after admission and the effects of prophylaxis with antimicrobial drugs on the development of bloodstream infections and 21-day mortality.

RESULTS

In our study population, 600 patients (39%) received antimicrobial prophylaxis and 226 patients (14.6%) developed at least 1 bloodstream infection. Exposure to antimicrobial drugs did not affect the proportion of patients who developed bloodstream infections (12.8% in patients with prophylaxis vs 15.7% in nonprophylaxed patients; P = .12), but a greater percentage of patients who received prophylaxis received liver transplants (28% vs 22%; P = .01). After adjusting for confounding factors, overall mortality within 21 days was associated independently with age (odds ratio [OR], 1.014), Model for End-stage Liver Disease score at admission (OR, 1.078), and vasopressor administration at admission (OR, 2.499). Low grade of coma (OR, 0.47) and liver transplantation (OR, 0.101) reduced mortality. Although bloodstream infection was associated significantly with 21-day mortality (P = .004), an interaction between bloodstream infection and etiology was detected: blood stream infection affected mortality to a greater extent in nonacetaminophen ALF patients (OR, 2.03) than in acetaminophen ALF patients (OR, 1.14).

CONCLUSIONS

Based on a large, observational study, antimicrobial prophylaxis does not reduce the incidence of bloodstream infection or mortality within 21 days of ALF. However, bloodstream infections were associated with increased 21-day mortality in patients with ALF-to a greater extent in patients without than with acetaminophen-associated ALF. Our findings do not support the routine use of antimicrobial prophylaxis in patients with ALF.

Effects of antimicrobial prophylaxis and blood stream infections in patients with acute liver failure: a retrospective cohort study

BACKGROUND & AIMS

We investigated whether antimicrobial prophylaxis alters the incidence of bloodstream infection in patients with acute liver failure (ALF), and whether bloodstream infections affect overall mortality within 21 days after development of ALF.

METHODS

We performed a retrospective cohort analysis of 1551 patients with ALF enrolled by the US Acute Liver Failure Study Group from January 1998 through November 2009. We analyzed data on infections in the first 7 days after admission and the effects of prophylaxis with antimicrobial drugs on the development of bloodstream infections and 21-day mortality.

RESULTS

In our study population, 600 patients (39%) received antimicrobial prophylaxis and 226 patients (14.6%) developed at least 1 bloodstream infection. Exposure to antimicrobial drugs did not affect the proportion of patients who developed bloodstream infections (12.8% in patients with prophylaxis vs 15.7% in nonprophylaxed patients; P = .12), but a greater percentage of patients who received prophylaxis received liver transplants (28% vs 22%; P = .01). After adjusting for confounding factors, overall mortality within 21 days was associated independently with age (odds ratio [OR], 1.014), Model for End-stage Liver Disease score at admission (OR, 1.078), and vasopressor administration at admission (OR, 2.499). Low grade of coma (OR, 0.47) and liver transplantation (OR, 0.101) reduced mortality. Although bloodstream infection was associated significantly with 21-day mortality (P = .004), an interaction between bloodstream infection and etiology was detected: blood stream infection affected mortality to a greater extent in nonacetaminophen ALF patients (OR, 2.03) than in acetaminophen ALF patients (OR, 1.14).

CONCLUSIONS

Based on a large, observational study, antimicrobial prophylaxis does not reduce the incidence of bloodstream infection or mortality within 21 days of ALF. However, bloodstream infections were associated with increased 21-day mortality in patients with ALF-to a greater extent in patients without than with acetaminophen-associated ALF. Our findings do not support the routine use of antimicrobial prophylaxis in patients with ALF.

Serial characterisation of monocyte and neutrophil function after lung resection

Objectives

The primary aim of this prospective study was to perform a comprehensive serial characterisation of monocyte and neutrophil function, circulating monocyte subsets, and bronchoalveolar lavage (BAL) fluid after lung resection. A secondary aim was to perform a pilot, hypothesis-generating evaluation of whether innate immune parameters were associated with postoperative pneumonia.

Methods

Forty patients undergoing lung resection were studied in detail. Blood monocytes and neutrophils were isolated preoperatively and at 6, 24 and 48 h postoperatively. BAL was performed preoperatively and immediately postoperatively. Monocyte subsets, monocyte responsiveness to lipopolysaccharide (LPS) and neutrophil phagocytic capacity were quantified at all time points. Differential cell count, protein and cytokine concentrations were measured in BAL. Pneumonia evaluation at 72 h was assessed using predefined criteria.

Results

After surgery, circulating subsets of classical and intermediate monocytes increased significantly. LPS-induced release of proinflammatory cytokines from monocytes increased significantly and by 48 h a more proinflammatory profile was found. Neutrophil phagocytosis demonstrated a small but significant fall. Factors associated with postoperative pneumonia were: increased release of specific proinflammatory and anti-inflammatory cytokines from monocytes; preoperative neutrophilia; and preoperative BAL cell count.

Conclusions

We conclude that postoperative lung inflammation is associated with specific changes in the cellular innate immune response, a better understanding of which may improve patient selection and prediction of complications in the future.

Uncontrolled sepsis: a systematic review of translational immunology studies in intensive care medicine

BACKGROUND

The design of clinical immunology studies in sepsis presents several fundamental challenges to improving the translational understanding of pathologic mechanisms. We undertook a systematic review of bed-to-benchside studies to test the hypothesis that variable clinical design methodologies used to investigate immunologic function in sepsis contribute to apparently conflicting laboratory data, and identify potential alternatives that overcome various obstacles to improve experimental design.

METHODS

We performed a systematic review of the design methodology employed to study neutrophil function (respiratory burst), monocyte endotoxin tolerance and lymphocyte apoptosis in the intensive care setting, over the past 15 years. We specifically focussed on how control samples were defined, taking into account age, gender, ethnicity, concomitant therapies, timing of sample collection and the criteria used to diagnose sepsis.

RESULTS

We identified 57 eligible studies, the majority of which (74%) used case-control methodology. Healthy volunteers represented the control population selected in 83% of studies. Comprehensive demographic data on age, gender and ethnicity were provided in ≤48% of case control studies. Documentation of diseases associated with immunosuppression, malignancy and immunomodulatory therapies was rare. Less than half (44%) of studies undertook independent adjudication for the diagnosis of sepsis while 68% provided microbiological data. The timing of sample collection was defined by highly variable clinical criteria. By contrast, surgical studies avoided many such confounders, although only one study in surgical patients monitored the study group for development of sepsis.

CONCLUSIONS

We found several important and common limitations in the clinical design of translational immunologic studies in human sepsis. Major elective surgery overcame many of these methodological limitations. The failure of adequate clinical design in mechanistic studies may contribute to the lack of translational therapeutic progress in intensive care medicine.

Sepsis-induced immunosuppression: from cellular dysfunctions to immunotherapy

Sepsis - which is a severe life-threatening infection with organ dysfunction - initiates a complex interplay of host pro-inflammatory and anti-inflammatory processes. Sepsis can be considered a race to the death between the pathogens and the host immune system, and it is the proper balance between the often competing pro- and anti-inflammatory pathways that determines the fate of the individual. Although the field of sepsis research has witnessed the failure of many highly touted clinical trials, a better understanding of the pathophysiological basis of the disorder and the mechanisms responsible for the associated pro- and anti-inflammatory responses provides a novel approach for treating this highly lethal condition. Biomarker-guided immunotherapy that is administered to patients at the proper immune phase of sepsis is potentially a major advance in the treatment of sepsis and in the field of infectious disease.

Upregulation of the inhibitory receptor ILT4 in monocytes from septic patients

Sepsis-induced immune dysfunction is a complex phenomenon that involves both innate and adaptive responses. Upregulation of the inhibitor receptor named immunoglobulin like transcript 4 (ILT4) is crucial to the tolerogenic function of monocytes. Here, ILT4 expression, endotoxin-induced IL-12 and IL-10 production and CD86 expression were investigated in circulating monocytes from 16 patients with severe sepsis and 16 age and sex matched controls. We found that monocytes from patients with severe sepsis express significantly higher levels of ILT4 than monocytes from controls. Upregulation of ILT4 expression appeared to be induced by soluble factors present in the serum of septic patients and directly correlated with the degree of organ dysfunction. ILT4(+) monocytes from septic patients also displayed an alteration in the cytokine response to endotoxin stimulation characterized by reduced IL-12 production and increased IL-10 production, and a reduced expression of the costimulatory molecule CD86. In conclusion, the increased ILT4 expression and IL-10 production and the decreased CD86 expression and IL-12 production indicate that during sepsis monocytes undergo substantial modulation of the surface and cytokine phenotype. These phenotypic changes may interfere with the antigen presenting cell activity of monocytes, which may contribute to the impairment of adaptive immune responses that takes place during sepsis.

Early biomarker activity in severe sepsis and septic shock and a contemporary review of immunotherapy trials: not a time to give up, but to give it earlier

Improving time to diagnosis and intervention has positively impacted outcomes in acute myocardial infarction, stroke, and trauma through elucidating the early pathogenesis of those diseases. This insight may partly explain the futility of time-insensitive immunotherapy trials for severe sepsis and septic shock. The aim of this study was to examine the early natural history of circulatory biomarker activity in sepsis, relative to previous animal and human outcome trials. We conducted a literature search using PubMed, MEDLINE, and Google Scholar to identify outcome trials targeting biomarkers with emphasis on the timing of therapy. These findings were compared with the biomarker activity observed over the first 72 h of hospital presentation in a cohort of severe sepsis and septic shock patients. Biomarker levels in animal and human research models are elevated within 30 min after exposure to an inflammatory septic stimulus. Consistent with these findings, the biomarker cascade is activated at the most proximal point of hospital presentation in our patient cohort. These circulatory biomarkers overlap; some have bimodal patterns and generally peak between 3 and 36 h while diminishing over the subsequent 72 h of observation. When this is taken into account, prior outcome immunotherapy trials have generally enrolled patients after peak circulatory biomarker concentrations. In previous immunotherapy sepsis trials, intervention was delayed after the optimal window of peak biomarker activity. As a result, future studies need to recalibrate the timing of enrollment and administration of immunotherapy agents that still may hold great promise for this deadly disease.

Circulating monocytes are not the major source of plasma cytokines in patients with sepsis

In sepsis, large quantities of inflammatory cytokines are released into the bloodstream. The cellular source of these cytokines is unclear, and we have here investigated to what extent circulating cells in blood contributed to this production. We used the enzyme-linked immunospot technique to study the spontaneous as well as the lipopolysaccharide (LPS)-induced secretion of the proinflammatory cytokines interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), granulocyte-macrophage colony-stimulating factor, IL-1β, IL-12p40, and the anti-inflammatory cytokine IL-10 from whole-blood cells. The study comprised 32 septic patients (24 with septic shock) and 30 healthy controls. Despite significantly increased plasma cytokine levels in the septic patients, the number of spontaneous cytokine-secreting cells was small or nonexistent and did not differ between the two groups. Lipopolysaccharide stimulation of cells from the same samples triggered substantially increased numbers of cytokine-producing cells in both patients and controls. However, although the numbers of IL-6- and tumor necrosis factor α-secreting monocytes were very similar in both groups, significantly fewer IL-1β-, IL-10-, IL-12p40-, and granulocyte-macrophage colony-stimulating factor-secreting monocytes were seen in samples from septic patients as compared with healthy controls. The reduced number of cytokine-secreting cells in response to LPS stimulation correlated with disease severity, as expressed by Sequential Organ Failure Assessment score and the stage of sepsis. In summary, circulating leukocytes did not appear to be responsible for the increased plasma levels of cytokines observed in sepsis. A selective sepsis-induced downregulation of cytokine secretion in response to LPS underscores the complexity of cytokine regulation in sepsis.

Optimizing antimicrobial therapy in sepsis and septic shock

Every patient with sepsis and septic shock must be evaluated thoroughly at presentation before the initiation of antibiotic therapy. However, in most situations, an abridged initial assessment focusing on critical diagnostic and management planning elements is sufficient. Intravenous antibiotics should be administered as early as possible, and always within the first hour of recognizing severe sepsis and septic shock. Broad-spectrum antibiotics must be selected with one or more agents active against likely bacterial or fungal pathogens and with good penetration into the presumed source. Antimicrobial therapy should be reevaluated daily to optimize efficacy, prevent resistance, avoid toxicity, and minimize costs. Consider combination therapy in Pseudomonas infections, and combination empiric therapy in neutropenic patients. Combination therapy should be continued for no more than 3 to 5 days and de-escalation should occur following availability of susceptibilities. The duration of antibiotic therapy typically is limited to 7 to 10 days; longer duration is considered if response is slow, if there is inadequate surgical source control, or in the case of immunologic deficiencies. Antimicrobial therapy should be stopped if infection is not considered the etiologic factor for a shock state.

Acute kidney injury: controversies revisited

This paper addresses the epidemiology of AKI specifically in relation to recent changes in AKI classification and revisits the controversies regarding the timing of initiation of dialysis and the use of peritoneal dialysis as a renal replacement therapy for AKI. In summary, the new RIFLE/AKIN classifications of AKI have facilitated more uniform diagnosis of AKI and clinically significant risk stratification. Regardless, the issue of timing of dialysis initiation still remains unanswered and warrants further examination. Furthermore, peritoneal dialysis as a treatment modality for AKI remains underutilised in spite of potential beneficial effects. Future research should be directed at identifying early reliable biomarkers of AKI, which in conjunction with RIFLE/AKIN classifications of AKI could facilitate well-designed large randomised controlled trials of early versus late initiation of dialysis in AKI. In addition, further studies of peritoneal dialysis in AKI addressing dialysis dose and associated complications are required for this therapy to be accepted more widely by clinicians.

C5a-mediated neutrophil dysfunction is RhoA-dependent and predicts infection in critically ill patients

Critically ill patients are at heightened risk for nosocomial infections. The anaphylatoxin C5a impairs phagocytosis by neutrophils. However, the mechanisms by which this occurs and the relevance for acquisition of nosocomial infection remain undetermined. We aimed to characterize mechanisms by which C5a inhibits phagocytosis in vitro and in critically ill patients, and to define the relationship between C5a-mediated dysfunction and acquisition of nosocomial infection. In healthy human neutrophils, C5a significantly inhibited RhoA activation, preventing actin polymerization and phagocytosis. RhoA inhibition was mediated by PI3Kδ. The effects on RhoA, actin, and phagocytosis were fully reversed by GM-CSF. Parallel observations were made in neutrophils from critically ill patients, that is, impaired phagocytosis was associated with inhibition of RhoA and actin polymerization, and reversed by GM-CSF. Among a cohort of 60 critically ill patients, C5a-mediated neutrophil dysfunction (as determined by reduced CD88 expression) was a strong predictor for subsequent acquisition of nosocomial infection (relative risk, 5.8; 95% confidence interval, 1.5-22; P = .0007), and remained independent of time effects as assessed by survival analysis (hazard ratio, 5.0; 95% confidence interval, 1.3-8.3; P = .01). In conclusion, this study provides new insight into the mechanisms underlying immunocompromise in critical illness and suggests novel avenues for therapy and prevention of nosocomial infection.

Immunosuppression following surgical and traumatic injury

Severe sepsis and organ failure are still the major causes of postoperative morbidity and mortality after major hepatobiliary pancreatic surgery. Despite recent progress in understanding the immune conditions of abdominal sepsis, the postoperative incidence of septic complications after major visceral surgery remains high. This review focuses on the clinical and immunological parameters that determine the risk of the development and lethal outcome of postoperative septic complication following major surgery and trauma. A review of the literature indicates that surgical and traumatic injury profoundly affects the innate and adaptive immune responses, and that a marked suppression in cell-mediated immunity following an excessive inflammatory response appears to be responsible for the increased susceptibility to subsequent sepsis. The innate and adaptive immune responses are initiated and modulated by pathogen-associated molecular-pattern molecules and by damage-associated molecular-pattern molecules through the pattern-recognition receptors. Suppression of cell-mediated immunity may be caused by multifaceted cytokine/inhibitor profiles in the circulation and other compartments of the host, excessive activation and dysregulated recruitment of polymorphonuclear neutrophils, induction of alternatively activated or regulatory macrophages that have anti-inflammatory properties, a shift in the T-helper (Th)1/Th2 balance toward Th2, appearance of regulatory T cells, which are potent suppressors of the innate and adaptive immune system, and lymphocyte apoptosis in patients with sepsis. Recent basic and clinical studies have elucidated the functional effects of surgical and traumatic injury on the immune system. The research studies of interest may in future aid in the selection of appropriate therapeutic protocols.

Optimizing antimicrobial therapy in sepsis and septic shock

This article reviews principles in the rational use of antibiotics in sepsis and septic shock and presents evidence-based recommendations for optimal antibiotic therapy. Every patient with sepsis and septic shock must be evaluated at presentation before the initiation of antibiotic therapy. However, in most situations, an abridged initial assessment focusing on critical diagnostic and management planning elements is sufficient. Intravenous antibiotics should be administered as early as possible, and always within the first hour of recognizing severe sepsis and septic shock. Broad-spectrum antibiotics must be selected with one or more agents active against likely bacterial or fungal pathogens and with good penetration into the presumed source. Antimicrobial therapy should be reevaluated daily to optimize efficacy, prevent resistance, avoid toxicity, and minimize costs. Consider combination therapy in Pseudomonas infections, and combination empiric therapy in neutropenic patients. Combination therapy should be continued for no more than 3 to 5 days and deescalation should occur following availability of susceptibilities. The duration of antibiotic therapy typically is limited to 7 to 10 days; longer duration is considered if response is slow, if there is inadequate surgical source control, or in the case of immunologic deficiencies. Antimicrobial therapy should be stopped if infection is not considered the etiologic factor for a shock state.

Induction of IL-10+ CD4+ CD25+ regulatory T cells with decreased NF-κB expression during immunotherapy

MyD88 is a major toll-like receptor (TLR) adaptor to activate NF-κB, which acts as a mater switch for allergic inflammation disease. Sterile hust dust extracts have been reported with TLR-dependent immunostimulatory activities. The aim of this study was to evaluate whether Dermatophagoides pteronyssinus (Der p) immunotherapy may increase IL-10+ CD4+ CD25+ T cells with modulating MyD88 signaling proteins, to decrease NF-κB expression. Peripheral blood mononuclear cells were isolated from patients before and after 1 yr of Der p immunotherapy, and also from matched control subjects. After 2 days of Der p-2 stimulation, intracellular IL-10 and Foxp3 expression of CD4(+) CD25(+) T cells were measured by flow-cytometry. The expression of IL-1 receptor-associated kinase (IRAK)-1 in cytoplasm and IFN-regulator factor-3 (IRF-3) with NF-κB/p65 in nuclei was determined by Western-blot analysis. Patients undergoing immunotherapy produced more soluble CD14, IL-10, and TGF-β that correlated with FEV(1) improvement (p < 0.05). In the immunotherapy group, the number of Foxp3+ CD4+ Treg cells increased more than the baseline status (25.06 ± 4.19 vs. 16.08 ± 3.54, p < 0.05). Additionally, increased IL-10 production with decreased IRAK-1 and NF-κB/p65 nuclear translocation was observed in sorted-purified Treg cells. IL-10(+) CD4(+) CD25(+) Treg cells may respond to Der p-2 and down-regulate NF-κB/p65 expression to maintain immune tolerance during immunotherapy.

Differential cytokine gene expression according to outcome in a hamster model of leptospirosis

Background

Parameters predicting the evolution of leptospirosis would be useful for clinicians, as well as to better understand severe leptospirosis, but are scarce and rarely validated. Because severe leptospirosis includes septic shock, similarities with predictors evidenced for sepsis and septic shock were studied in a hamster model.

Methodology/Principal Findings

Using an LD50 model of leptospirosis in hamsters, we first determined that 3 days post-infection was a time-point that allowed studying the regulation of immune gene expression and represented the onset of the clinical signs of the disease. In the absence of tools to assess serum concentrations of immune effectors in hamsters, we determined mRNA levels of various immune genes, especially cytokines, together with leptospiraemia at this particular time-point. We found differential expression of both pro- and anti-inflammatory mediators, with significantly higher expression levels of tumor necrosis factor α, interleukin 1α, cyclo-oxygenase 2 and interleukin 10 genes in nonsurvivors compared to survivors. Higher leptospiraemia was also observed in nonsurvivors. Lastly, we demonstrated the relevance of these results by comparing their respective expression levels using a LD100 model or an isogenic high-passage nonvirulent variant.

Conclusions/Significance

Up-regulated gene expression of both pro- and anti-inflammatory immune effectors in hamsters with fatal outcome in an LD50 model of leptospirosis, together with a higher Leptospira burden, suggest that these gene expression levels could be predictors of adverse outcome in leptospirosis.

Leptospirosis is a widespread bacterial infection that is transmitted by soil or water contaminated by the urine of infected animals, or directly from these animals. It has highly diverse clinical presentations, making its differential diagnosis difficult. Though most cases are minor and self-resolving, there are also severe forms that include a sepsis pattern and multiple organ failure, and have possible fatal outcomes. Predictors of disease evolution and outcome are scarce, yet they would be very valuable to clinicians as well as to better decipher disease pathogenesis. In this study, we used a hamster model of leptospirosis to evaluate if immune genes were differentially expressed between individuals and if their expression levels could help forecast the outcome of the disease. We found that hamsters that later died from leptospirosis had significantly higher expression levels of both pro- and anti-inflammatory mediators compared to survivors. These results suggest that expression levels of these immune effectors might be helpful predictors of outcome in leptospirosis and that septic shock contributes to fatal leptospirosis.

Endotoxin tolerance: new mechanisms, molecules and clinical significance

Prior exposure of innate immune cells like monocytes/macrophages to minute amounts of endotoxin cause them to become refractory to subsequent endotoxin challenge, a phenomenon called "endotoxin tolerance". Clinically, this state is associated with monocytes/macrophages in sepsis patients where they contribute to "immunosuppression" and mortality. The molecular mechanisms underlying endotoxin tolerance remain elusive. The recent appreciation of inflammation as a self-regulating process, the relative contribution of MyD88 versus TRIF signaling pathways in inducing activation or tolerance, plasticity of NF-kappaB function and the role of chromatin modification and microRNAs in LPS-induced gene reprogramming urges a re-evaluation of endotoxin tolerance. This review integrates these new findings into an up-to-date account of endotoxin tolerance, its molecular basis and clinical implications in different pathologies.

Improvement of monocyte function and immune homeostasis by high volume continuous venovenous hemofiltration in patients with severe acute pancreatitis

BACKGROUND

Continuous renal replacement therapy (CRRT) showed promising results in the management of critically ill patients with systemic inflammatory response syndrome (SIRS)/sepsis. However, the underlying mechanism is still not very clear. A change of immune homeostasis in critically ill patients during CRRT was observed only to a smaller degree.

OBJECTIVE

The purpose of this study was to test the hypothesis that high-volume continuous venovenous hemofiltration (HV-CVVH) treatment could improve monocyte function and restore immune homeostasis in patients with severe acute pancreatitis (SAP).

METHODS

This was a prospective clinical trial in the surgical intensive care unit of a teaching hospital. Subjects were 16 patients with severe acute pancreatitis: sepsis group (n=7): positive culture result and in the late phase of disease (from onset of SAP to receiving CVVH therapy: more than 3 days); and nonseptic group (n=9): negative culture result and early phase of disease (less than 3 days). Patients received 72 hours of HV-CVVH. We measured the change in mean arterial pressure, APACHE II score, monocyte functions (including antigen-presenting and cytokine production ability), and plasma cytokines.

RESULTS

Mean arterial pressure were stable accompanied with APACHE II score improvements. HLA-DR expression on monocytes (antigen-presenting ability) were markedly decreased (p<0.0001) in all patients. Lipopolysaccharide (LPS)-induced TNF-alpha, interleukin-6 (IL-6), and IL-10 production from patients' monocytes markedly decreased in septic patients, but significantly increased in nonseptic patients. During HV-CVVH treatment, HLA-DR expression was markedly increased in nonseptic patients in 24 hours (p<0.05), and in septic patients in 72 hours (p<0.05). LPS-induced cytokine production was decreased in nonseptic patients, but not significantly changed in septic patients. The change of plasma cytokines showed the same trend.

CONCLUSIONS

In patients with SAP, HV-CVVH was associated with improved hemodynamics. HV-CVVH restores monocytes functions, especially in patients in the early phase of the disease and without sepsis. These findings suggest a potential role for HV-CVVH in the treatment of SAP.

Endotoxin tolerance in sepsis: concentration-dependent augmentation or inhibition of LPS-stimulated macrophage TNF secretion by LPS pretreatment

BACKGROUND

We previously showed that macrophages (MPhi) pretreated with bacterial endotoxin (lipopolysaccharide [LPS]) develop an altered state of LPS-responsiveness--"LPS tolerance": LPS tolerance was associated with inhibition of tumor necrosis factor (TNF) release and decreased extracellular signal-regulated kinase and p38 kinase activation when MPhi were restimulated with LPS. However, the concentration of LPS used for pretreatment (most frequently 10 ng/mL) may be much higher than LPS concentrations observed in patients. Therefore, in the current study we examined the effect of lower and higher pretreatment LPS concentrations on subsequent LPS-stimulated MPhi responses.

METHODS

RAW 264.7 MPhi-like cells were pretreated in vitro (PreRx) for 24 hours in medium or a range of LPS concentrations (0 ng/mL, 1 ng/mL, 10 ng/mL, or 100 ng/mL of E. coli 0111B4 LPS). Culture medium was discarded after 24 hours and MPhi were restimulated with LPS (0 ng/mL, 1 ng/mL, 10 ng/mL or 100 ng/mL). Three different lots of LPS (Sigma) were used. Supernatant TNF secretion at 3 hour was measured using enzyme-linked immunosorbent assay (pg/mL +/- SEM). Statistics by Chi-square and student's t test.

RESULTS

Pretreatment with 100 ng/mL of LPS profoundly inhibited TNF release at all LPS restimulation concentrations (p < 0.05 vs. Medium PreRx). In contrast, very low dose LPS pretreatment (1 ng/mL) significantly augmented TNF release versus medium (p < 0.05). There was no further augmentation observed when even lower doses of LPS (0.1 ng/mL) were used for pretreatment. Similar results were obtained with three different lots E. coli 0111B4 LPS or using LPS from E. coli 0127B8.

CONCLUSION

Prior exposure of MPhi to bacterial ligands alters MPhi cytokine production in response to subsequent LPS-stimulated activation. This modulated MPhi response is critically dependent on the concentration of LPS pretreatment.

The importance of immune dysfunction in determining outcome in acute liver failure

Acute liver failure (ALF) shares striking similarities with septic shock with regard to the features of systemic inflammation, progression to multiple organ dysfunction and functional immunoparesis. While the existence of opposing systemic pro- and anti-inflammatory profiles resulting in organ failure and immune dysfunction are well recognised in septic shock, characterization of these processes in ALF has only recently been described. This review explores the evolution of the systemic inflammation in acute liver failure, its relation to disease progression, exacerbation of liver injury and development of innate immune dysfunction and extra-hepatic organ failure as sequelae. Defects in innate immunity are described in hepatic and extra-hepatic compartments. Clinical studies measuring levels of pro- and anti-inflammatory cytokines and expression of the antigen presentation molecule HLA-DR on monocytes, in combination with ex-vivo experiments, demonstrate that the persistence of a compensatory anti-inflammatory response syndrome, leading to functional monocyte deactivation, is a central event in the evolution of systemic immune dysfunction. Accurate immune profiling in ALF may permit the development of immunomodulatory strategies in order to improve outcome in this condition.

Downregulation of CD40 ligand response in monocytes from sepsis patients

It has been suggested that a defective adaptive immune response contributes to septic immunosuppression. Here, the response of monocytes to CD40 ligand (CD40L) for patients with sepsis due to infection with gram-negative organisms has been analyzed. Compared to cells from controls, monocytes from septic patients showed significantly reduced production of tumor necrosis factor alpha, interleukin-1beta (IL-1beta), and IL-12 and were unable to acquire high levels of CD80 and CD86 molecules. These alterations were observed at the onset of sepsis and persisted at day 7. However, the ability of monocytes to respond to CD40L stimulation was partially but significantly restored in cells from patients who recovered from sepsis. In addition, costimulation of autologous CD4+ T lymphocytes by CD40L-activated monocytes from septic patients failed to induce cell proliferation and gamma interferon production. Finally, the ability of CD40L to rescue monocytes from apoptosis was severely impaired. We conclude that downregulation of the CD40L response may be an appropriate model for the monocyte alteration observed during septic immunosuppression and may help in the development of novel therapeutic strategies.

Monitoring immune dysfunctions in the septic patient: a new skin for the old ceremony

Septic syndromes represent a major although largely underrecognized healthcare problem worldwide, accounting for thousands of deaths every year. It is now agreed that sepsis deeply perturbs immune homeostasis by inducing an initial tremendous systemic inflammatory response which is accompanied by an antiinflammatory process, acting as negative feedback. This compensatory inhibitory response secondly becomes deleterious as nearly all immune functions are compromised. These alterations might be directly responsible for worsening outcome, as they may play a major role in the decreased resistance to nosocomial infections in patients who survived initial resuscitation. Consequently, immunostimulatory therapies may now be assessed for the treatment of sepsis. This review focuses on immune dysfunctions described in septic patients and on their potential use as markers on a routine standardized basis for prediction of adverse outcome or of occurrence of secondary nosocomial infections. This constitutes a prerequisite to a staging system for individualized treatment for these hitherto deadly syndromes.

Maternal and neonatal lipopolysaccharide and Fas responses are altered by antenatal risk factors for sepsis

The diagnosis of neonatal sepsis is difficult, resulting in unnecessary treatment to minimize morbidity and mortality. We hypothesized that exposure to antenatal risk factors for sepsis alters the perinatal neutrophil phenotype. The study setting was a tertiary referral university-affiliated maternity and neonatal hospital. Neutrophils from adults, normal neonates, neonates with antenatal sepsis risk factors and their respective maternal samples were incubated alone, with agonistic Fas antibody or with lipopolysaccharide (LPS). Surface receptor CD11b expression and the percentage apoptosis (persistent inflammatory response) were assessed using flow cytometry. Both mothers and asymptomatic neonates exposed to maternal sepsis risk factors had increased spontaneous neutrophil apoptosis compared to their respective controls. Infants with sepsis were LPS and Fas hyporesponsive. Maternal neutrophils had a delay in apoptosis in all groups with enhanced LPS and Fas responses associated with neonatal sepsis. CD11b expression was not altered significantly between groups. Maternal neutrophil function is altered in neonatal sepsis and may have a diagnostic role. Neonatal sepsis was associated with LPS hyporesponsiveness, potentially increasing susceptibility to infection.

Role for MyD88-independent, TRIF pathway in lipid A/TLR4-induced endotoxin tolerance

Repeated exposure to low doses of endotoxin results in progressive hyporesponsiveness to subsequent endotoxin challenge, a phenomenon known as endotoxin tolerance. In spite of its clinical significance in sepsis and characterization of the TLR4 signaling pathway as the principal endotoxin detection mechanism, the molecular determinants that induce tolerance remain obscure. We investigated the role of the TRIF/IFN-beta pathway in TLR4-induced endotoxin tolerance. Lipid A-induced homotolerance was characterized by the down-regulation of MyD88-dependent proinflammatory cytokines TNF-alpha and CCL3, but up-regulation of TRIF-dependent cytokine IFN-beta. This correlated with a molecular phenotype of defective NF-kappaB activation but a functional TRIF-dependent STAT1 signaling. Tolerance-induced suppression of TNF-alpha and CCL3 expression was significantly relieved by TRIF and IFN regulatory factor 3 deficiency, suggesting the involvement of the TRIF pathway in tolerance. Alternatively, selective activation of TRIF by poly(I:C)-induced tolerance to lipid A. Furthermore, pretreatment with rIFN-beta also induced tolerance, whereas addition of IFN-beta-neutralizing Ab during the tolerization partially alleviated tolerance to lipid A but not TLR2-induced endotoxin homo- or heterotolerance. Furthermore, IFNAR1-/- murine embryonal fibroblast and bone-marrow derived macrophages failed to induce tolerance. Together, these observations constitute evidence for a role of the TRIF/IFN-beta pathway in the regulation of lipid A/TLR4-mediated endotoxin homotolerance.

Etoposide attenuates zymosan-induced shock in mice

Zymosan-induced generalized inflammation is a convenient model to study the process of acute and chronic inflammatory processes resulting in multiple organ dysfunction syndrome. Macrophages as a source of many pro-inflammatory mediators are the major players in shock and further organ failure. Etoposide is a cytostatic drug known to reduce macrophages and monocytes in blood circulation. In the present study we have investigated whether the ability of etoposide to diminish macrophage number would have an impact on the course of zymosan-induced shock. The drug injected at a dose of 10 mg/kg 1 day before zymosan, significantly reduced the mortality and decreased the organ toxicity in Balb/c mice. Simultaneously, an inhibition of TNF-alpha production by alveolar and peritoneal macrophages was observed. Etoposide administered into mice with severe combined immunodeficiency (SCID) did not change the survival rate and had a little influence on organ toxicity. Our findings suggest that the beneficial action of etoposide might be attributed to the reduction of macrophages and alteration of their functions. Its effect depends on the presence of functional T and B lymphocytes. The results deserve further investigation of etoposide as a perspective therapeutic tool for inhibiting the excessive inflammatory response and to be helpful for revealing mechanisms of shock development.

Inflammatory responses associated with acute coronary syndrome up-regulate IRAK-M and induce endotoxin tolerance in circulating monocytes

Acute coronary syndrome (ACS) groups different cardiac diseases whose development is associated with inflammation. Here we have analyzed the levels of inflammatory cytokines and of members of the TLR/IRAK pathway including IRAK-M in monocytes from ACS patients classified as either UA (unstable angina), STEMI (ST-elevation myocardial infarction) or NSTEMI (non-ST-elevation myocardial infarction). Circulating monocytes from all patients, but not from healthy individuals, showed high levels of pro-inflammatory cytokines, TNF-alpha and IL-6, as well as of IRAK-M and IL-10. TLR4 was also up-regulated, but IRAK-1, IRAK-4 and MyD88 levels were similar in patients and controls. Further, we investigated the consequences of cytokines/IRAK-M expression on the innate immune response to endotoxin. Ex vivo responses to LPS were markedly attenuated in patient monocytes compared to controls. Control monocytes cultured for 6 h in supplemented medium (10% serum from ACS patients) expressed IRAK-M, and LPS stimulation failed to induce TNF-alpha and IL-6 in these cultures. Pre-incubation of the serum with a blocking anti-TNF-alpha antibody reduced this endotoxin tolerance effect, suggesting that TNF-alpha controls this phenomenon, at least partially. We show for the first time that inflammatory responses associated with ACS induce an unresponsiveness state to endotoxin challenge in circulating monocytes, which correlates with expression of IRAK-M, TLR4 and IL-10. The magnitude of this response varies according to the clinical condition (UA, STEMI or NSTEMI), and is regulated by TNF-alpha.

Cytokine production and hospital mortality in patients with sepsis-induced stress hyperglycemia

OBJECTIVES

To investigate whether stress hyperglycemia affects the production of the main pro- and anti-inflammatory cytokines and the 28-day hospital mortality in patients with severe sepsis.

METHODS

The study included 62 patients with severe sepsis, divided in three groups according to their glycemic profile within 24h after admission: patients with stress hyperglycemia (group SH, n=16), diabetes mellitus type II (group DM, n=27), and normal glucose levels (group NG, n=19). The serum levels of the cytokines TNF-alpha, IL-6, IL-10 and TGFbeta-1 were measured within 24h after admission.

RESULTS

A higher percentage of septic patients with stress hyperglycemia died compared to diabetic patients (43.7 vs. 14.8%) and group NG (43.7 vs. 5.2%). Group SH had higher SOFA score and levels of IL-6 and IL-10 than group DM and group NG. It also had higher levels of TNF-alpha than group DM but not group NG. There was no difference in the levels of TGFbeta-1 among the three groups. Non-survivors had higher levels of IL-10, no difference was detected for IL-6, TNF-alpha, IL-10/TNF-alpha ratio and TGFbeta-1. Interleukin-10 values, mean fasting glucose values and age were found as prognostic factors associated with outcome.

CONCLUSIONS

Stress hyperglycemia is associated with increased cytokine production and an adverse clinical outcome in patients with severe sepsis.

Repeat organic dust exposure-induced monocyte inflammation is associated with protein kinase C activity

BACKGROUND

Organic dust exposure results in an inflammatory response that attenuates over time, but repetitive exposures can result in chronic respiratory diseases. Mechanisms underlying this modulated response are not clear.

OBJECTIVE

This study investigated the effects of repeat versus single organic dust exposure-induced inflammatory mediators and protein kinase C (PKC) activity in monocytes.

METHODS

Settled organic dust was obtained from swine confinement facilities. Promonocytic THP-1 cells and human peripheral blood monocytes were pretreated with or without dust extract and then restimulated. Culture supernatants were evaluated for TNF-alpha, IL-6, CXCL8, and IL-10. Responses were compared with endotoxin-depleted dust, LPS, and peptidoglycan. PKC isoform (alpha, delta, epsilon, zeta) activation was evaluated by direct kinase activity. PKC isoform inhibitors' effects on TNF-alpha secretion were studied.

RESULTS

Single exposure to organic dust stimulated monocyte secretion of TNF-alpha, IL-6, CXCL8, and IL-10 compared with unstimulated cells. TNF-alpha and IL-6 were diminished in pretreated cells restimulated with dust. Secretion of CXCL8 and IL-10 remained persistently elevated. TNF-alpha responses were retained after marked depletion of endotoxin. Dust exposure induced significant PKC alpha, delta, epsilon, and zeta activation, peaking at 30 to 60 minutes. PKC isoform activation was attenuated in repeat exposed cells. Inhibition of PKCalpha and PKCepsilon reduced dust-induced TNF-alpha secretion.

CONCLUSION

Repeat organic dust exposure modulated inflammatory mediator production in monocytes independent of endotoxin. The inability of PKC to be reactivated may account for this observation.

CLINICAL IMPLICATIONS

Targeting PKC and specific mediators associated with repetitive organic dust exposure may result in novel therapeutic strategies.