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Background: iNKT-cells are innate regulatory lymphocytes capable of directing immune and inflammatory responses to sepsis. Repeat stimulation of iNKT-cells leads to the induction of anergy with the emergence of a hyporesponsive CD3lowiNKT-cell subpopulation. Methods: iNKT-cells were isolated from critical ill surgical patients with sepsis and phenotyped for CD3 expression. This was correlated with degree of severity of illness, as denoted by APACHE-II score. Results: Comparing healthy volunteers to critically ill septic patients, it was noted that increasing severity of sepsis was associated with increasing frequency of circulating CD3low-iNKT-cell populations. Conclusion: The emergence of CD3low -iNKT-cells may serve as a clinically translatable marker of degree of sepsis-induced immune dysfunction. [ABSTRACT FROM AUTHOR]

Every year numerous individuals develop the morbid condition of sepsis. Therefore, novel biomarkers that might better inform clinicians treating such patients are sorely needed. Difficulty in identifying such markers is in part due to the complex heterogeneity of sepsis, resulting from the broad and vague definition of this state/condition based on numerous possible clinical signs and symptoms as well as an incomplete understanding of the underlying pathobiology of this complex condition. This review considers some of the attempts that have been made sofar, looking at both the pro- and anti-inflammatory response to sepsis, as well as genomic analysis, as sources of potential biomarkers. Irrespective, for functional biomarker(s) of sepsis to successfully translate from the laboratory to a clinical setting, the biomarker must be target specific and sensitive as well as easy to implement/interpret, and be cost effective, such that they can be utilized routinely in patient diagnosis and treatment. [ABSTRACT FROM AUTHOR]

Alterations in the apoptotic process in lymphoid tissues is a common condition which is encountered in the severely septic animal and critically ill patient. Here we attempt to delineate the pathological significance of these apoptotic changes and the role of Fas-FasL mediated contribution to this process. [ABSTRACT FROM AUTHOR]

Today, despite the application of contemporary operative/pharmacological approaches in the treatment of the critically ill trauma/surgery patient, we are still faced with a high incidence of patients who develop sepsis and subsequent multiple organ failure. This review attempts to summarize data gathered over the last few years, from both experimental and patient settings, that not only documents the presence of apoptosis, but begins to define its contribution to the pathology of sepsis and shock, which in turn precipitate organ injury/damage. [Copyright &y& Elsevier]

Studies the mechanism of diltiazem's immunomodulatory response after hemorrhage and resuscitation. Splenic microvascular blood flow; ATP levels and cytoplasmic free Ca2+ concentrations; Interleukin and tumor necrosis factor concentrations; Decrease in Ca2+-induced splenocyte injury.

Determines the effects of low dose tumor necrosis factor-alpha (TNF-alpha) on hepatocellular function. Determination of hemodynamic parameters and plasma glucose concentration.

Investigates the role of testosterone in the production of splenocyte immune depression after hemorrhagic trauma. Methodology used in the study; Differences in the cell-mediated immune response of men and women; Results and discussion.

Investigates the role of male sex steroids in the macrophage immune function after trauma-hemorrhage. Cytokine release by peritoneal and splenic macrophages; Interleukin-6 release by Kupffer cells; Plasma testerone levels; Potential of androgen-blocking agents to reverse the immunodepression associated with trauma-hemorrhage.

Reports on a study which investigated the production of splenocyte in immune depression after trauma hemorrhage. Prevention of the depression of cell-mediated immunity; Questioning whether testosterone produces immune depression; Methodology used to conduct the study; Results of the study.

Presents a study which looks at whether androgen depletion before trauma-hemorrhage also has salutary effects on splenic and peritoneal macrophage as well as on Kupffer cell function. Detailed information on the methodology used to conduct the study; Discussion based on the results of the study.

G-protein-coupled receptors (GPCRs) have a central role not only in the competent development of an innate myeloid response to foreign pathogens but, if dysregulated, might contribute to phagocyte-mediated organ injury. Here, recent findings from a study in which neutrophil trafficking is inhibited by using a novel family of GPCR signaling inhibitors, known as pepducins, are discussed. [Copyright &y& Elsevier]

Background: Pre-clinical animal studies precede the majority of clinical trials. While the clinical definitions of sepsis and recommended treatments are regularly updated, a systematic review of pre-clinical models of sepsis has not been done and clear modeling guidelines are lacking.Objective: To address this deficit, a Wiggers-Bernard Conference on pre-clinical sepsis modeling was held in Vienna in May 2017. The goal of the conference was to identify limitations of pre-clinical sepsis models and to propose a set of guidelines, defined as the “Minimum Quality Threshold in Pre-Clinical Sepsis Studies” (MQTiPSS), to enhance translational value of these models.Methods: A total of 31 experts from 13 countries participated and were divided into 6 thematic working groups (WG): (1) study design, (2) humane modeling, (3) infection types, (4) organ failure/dysfunction, (5) fluid resuscitation, and (6) antimicrobial therapy endpoints. As basis for the MQTiPSS discussions, the participants conducted a literature review of the 260 most highly cited scientific articles on sepsis models (2002-2013).Results: Overall, the participants reached consensus on 29 points; 20 at “recommendation” (R) and 9 at “consideration” (C) strength. This executive summary provides a synopsis of the MQTiPSS consensus (Tables 1, 2, and 3). Detailed commentaries to all Rs and Cs are simultaneously published in three separate full-length papers.Conclusions: We believe that these recommendations and considerations will serve to bring a level of standardization to pre-clinical models of sepsis and ultimately improve translation of pre-clinical findings. These guideline points are proposed as “best practices” for animal models of sepsis that should be implemented. In order to encourage its wide dissemination, this article is freely accessible in Shock, Infection and Intensive Care Medicine Experimental. [ABSTRACT FROM AUTHOR]

The article comments on a study by R. Oberbeck and colleagues titled "Dopamine Affects Cellular Immune Functions During Poly-Microbial Sepsis." It mentions the limitations of the study. It also suggests that future studies should be considered in animals which look at the effect of dopamine in presence or absence of genes that play a more direct role in the functions of these immune cells and/or the onset of apoptosis.

COVID-19 has impacted millions of patients across the world. Molecular testing occurring now identifies the presence of the virus at the sampling site: nasopharynx, nares, or oral cavity. RNA sequencing has the potential to establish both the presence of the virus and define the host's response in COVID-19. Single center, prospective study of patients with COVID-19 admitted to the intensive care unit where deep RNA sequencing (> 100 million reads) of peripheral blood with computational biology analysis was done. All patients had positive SARS-CoV-2 PCR. Clinical data was prospectively collected. We enrolled fifteen patients at a single hospital. Patients were critically ill with a mortality of 47% and 67% were on a ventilator. All the patients had the SARS-CoV-2 RNA identified in the blood in addition to RNA from other viruses, bacteria, and archaea. The expression of many immune modulating genes, including PD-L1 and PD-L2, were significantly different in patients who died from COVID-19. Some proteins were influenced by alternative transcription and splicing events, as seen in HLA-C, HLA-E, NRP1 and NRP2. Entropy calculated from alternative RNA splicing and transcription start/end predicted mortality in these patients. Current upper respiratory tract testing for COVID-19 only determines if the virus is present. Deep RNA sequencing with appropriate computational biology may provide important prognostic information and point to therapeutic foci to be precisely targeted in future studies. [ABSTRACT FROM AUTHOR]

Background: Sepsis-related mortality is driven by immune dysfunction. A bidirectional micro-organism-immune cell cross talks exists. Gut Bacteroides fragilis-T-cell crosstalk maintains innate immune cell/pathogen homeostasis. Commensal gut Clostridia spp. suppress inflammation and induce gut tolerance. Probiotics are administered to restore immune microbiome homeostasis. Individual microbial components have an immunomodulatory effect. However, probiotic therapies for sepsis-induced immune disruptions are rarely tailored to specific immune responses. Thus, we ask the question as to how components of the intestinal microbiome, often found in probiotic therapies, affect lymphocyte phenotypic profile? Methods: T-lymphocytes were cultured with either monomicrobial or polymicrobial combinations. Microbes used were Bacteroides fragilis, Clostridium perfringens, or Lactobacillus acidophilus. Cytokines, measured by enzyme-linked immunosorbent assay (ELISA)-included interleukin (IL)-6, IL-10, IL-22, and IL-33. Flow cytometry was used for T-cell phenotyping for program-death receptor-1 (PD-1) and B- and T-lymphocyte attenuator (BTLA). T-cell DNA was extracted to assess global epigenetic changes. For translation, IL-33 was measured from surgical intensive care unit (ICU) patients with sepsis with either monomicrobial or polymicrobial infection. Results:Lactobacillus consistently induced IL-22 and IL-33. Bacteroides fragilis induced IL-33 only under polymicrobial (pB) conditions. Within surgical ICU patients, IL-33 levels were higher in polymicrobial versus monomicrobial patients. PD-1+ expression was lowest with either monomicrobial Bacteroides fragilis or Bacteroides fragilis predominant polymicrobial context. Conversely Bacteroides fragilis exposure induced a distinct PD-1-high subpopulation. B- and T-lymphocyte attenuator-positive expression did not differ after individual microbes. Among polymicrobial conditions, Bacteroides fragilis predominant (pB) and Lactobacillus acidophilus predominant (pL) increased BTLA+ expression. DNA methylation was most increased in response to Clostridium perfringens in monomicrobial and in response to Bacteroides fragilis in polymicrobial conditions. Conclusion: Unique microbe/lymphocyte interactions occur. Bacteroides fragilis induced a T-cell phenotype consistent with potential long-term immune recovery. This work begins to discover how varying microbes may induce unique functional and phenotypic T-lymphocyte responses. [ABSTRACT FROM AUTHOR]

This study sets out to establish the comparative contribution of PD-L1 expression by pulmonary endothelial cells (ECs) and/or epithelial cells (EpiCs) to the development of indirect acute lung injury (iALI) by taking advantage of the observation that treatment with naked siRNA by intratracheal delivery in mice primarily affects lung EpiCs, but not lung ECs, while intravenous delivery of liposomal-encapsulated siRNA largely targets vascular ECs including the lung, but not pulmonary EpiCs. We showed that using a mouse model of iALI [induced by hemorrhagic shock followed by septic challenge (Hem-CLP)], PD-L1 expression on pulmonary ECs or EpiCs was significantly upregulated in the iALI mice at 24 h post-septic insult. After documenting the selective ability of intratracheal versus intravenous delivery of PD-L1 siRNA to inhibit PD-L1 expression on EpiCs versus ECs, respectively, we observed that the iALI-induced elevation of cytokine/chemokine levels (in the bronchoalveolar lavage fluid, lung lysates, or plasma), lung myeloperoxidase and caspase-3 activities could largely only be inhibited by intravenous, but not intratracheal, delivery of PD-L1 siRNA. Moreover, intravenous, but not intratracheal, delivery led to a preservation of normal tissue architecture, lessened pulmonary edema, and reduced neutrophils influx induced by iALI. In addition, in vitro mouse endothelial cell line studies showed that PD-L1 gene knockdown by siRNA or knockout by CRISPR/Cas9-mediated gene manipulation, reduced monolayer permeability, and maintained tight junction protein levels upon recombinant IFN-γ stimulation. Together, these data imply a critical role for pulmonary vascular ECs in mediating PD-1:PD-L1-driven pathological changes resulting from systemic stimuli such as Hem-CLP. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa infections are increasingly multidrug resistant and cause healthcare‐associated pneumonia, a major risk factor for acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Adenosine is a signaling nucleoside with potential opposing effects; adenosine can either protect against acute lung injury via adenosine receptors or cause lung injury via adenosine receptors or equilibrative nucleoside transporter (ENT)‐dependent intracellular adenosine uptake. We hypothesized that blockade of intracellular adenosine uptake by inhibition of ENT1/2 would increase adenosine receptor signaling and protect against P. aeruginosa–induced acute lung injury. We observed that P. aeruginosa (strain: PA103) infection induced acute lung injury in C57BL/6 mice in a dose‐ and time‐dependent manner. Using ENT1/2 pharmacological inhibitor, nitrobenzylthioinosine (NBTI), and ENT1‐null mice, we demonstrated that ENT blockade elevated lung adenosine levels and significantly attenuated P. aeruginosa–induced acute lung injury, as assessed by lung wet‐to‐dry weight ratio, BAL protein levels, BAL inflammatory cell counts, pro‐inflammatory cytokines, and pulmonary function (total lung volume, static lung compliance, tissue damping, and tissue elastance). Using both agonists and antagonists directed against adenosine receptors A2AR and A2BR, we further demonstrated that ENT1/2 blockade protected against P. aeruginosa –induced acute lung injury via activation of A2AR and A2BR. Additionally, ENT1/2 chemical inhibition and ENT1 knockout prevented P. aeruginosa–induced lung NLRP3 inflammasome activation. Finally, inhibition of inflammasome prevented P. aeruginosa–induced acute lung injury. Our results suggest that targeting ENT1/2 and NLRP3 inflammasome may be novel strategies for prevention and treatment of P. aeruginosa–induced pneumonia and subsequent ARDS. [ABSTRACT FROM AUTHOR]

The liver is an organ that, when dysfunctional in a septic patient, is strongly associated with morbidity and mortality. Understanding the pathophysiology of liver failure during sepsis may lead to improved diagnostics and potential therapeutic targets. Historically, programmed cell death receptor (PD) ligand 1 (PD-L1) has been considered the primary ligand for its checkpoint molecule counterpart, PD-1, with PD-L2 rarely in the immunopathological spotlight. PD-1 and PD-L1 contribute to liver dysfunction in a murine cecal ligation and puncture (CLP) model of sepsis, but virtually nothing is known about PD-L2's role in sepsis. Therefore, our central hypothesis was that sepsis-induced changes in hepatic PD-L2 expression contributed to worsened liver function and, subsequently, more pronounced morbidity and mortality. We found that although PD-L1 gene deficiency attenuated the hepatic dysfunction seen in wild-type mice after CLP, the loss of PD-L2 appeared to actually worsen indices of liver function along with a trend toward higher liver tissue vascular permeability. Conversely, some protective effects of PD-L2 gene deletion were noted, such as reduced liver/peritoneal bacterial load and reduced IL-6, IL-10, and macrophage inflammatory protein 2 levels following CLP. These diverse actions, as well as the unique expression pattern of PD-L2, may explain why no overt survival advantage could be witnessed in the septic PD-L2-/- mice. Taken together, these data suggest that although PD-L2 has some selective effects on the hepatic response seen in the septic mouse, these factors are not sufficient to alter septic mortality in this adult murine model. [ABSTRACT FROM AUTHOR]

Dear Editor, Critically ill patients develop acute respiratory distress syndrome (ARDS) [[1]] and despite the study of genomics of ARDS, there is little progress [[2]]. The objective of this investigation is to utilize RNA sequencing data and analysis to identify novel gene targets in ARDS. In this analysis of RNA sequencing data from deceased patients with ARDS identified by the presence of DAD and a clinically relevant mouse model of ARDS, novel genes were identified. [Extracted from the article]

Indirect acute respiratory distress syndrome (iARDS) is caused by a nonpulmonary inflammatory process resulting from insults such as nonpulmonary sepsis. Neutrophils are thought to play a significant role in mediating ARDS, with the development of iARDS being characterized by dysregulation and recruitment of activated neutrophils into the lung. Recently, a novel mechanism of microbial killing by neutrophils was identified through the formation of neutrophil extracellular traps (NETs). NETs are composed of large webs of decondensed chromatin released from activated neutrophils into the extracellular space; they are regulated by the enzyme peptidylarginine deiminase 4 (PAD4) through mediation of chromatin decondensation via citrullination of target histones. Components of NETs have been implicated in ARDS. However, it is unknown whether there is any pathological significance of NET formation in ARDS caused indirectly by nonpulmonary insult. We subjected PAD4-/- mice and wild-type mice to a "two-hit" model of hypovolemic shock (fixed-pressure hemorrhage [Hem]) followed by septic cecal ligation and puncture (CLP) insult (Hem/ CLP). Mice were hemorrhaged and resuscitated; 24 h after Hem, mice were then subjected to CLP. Overall, PAD4 deletion led to an improved survival as compared with wild-type mice. PAD4-/- mice displayed a marked decrease in neutrophil influx into the lung, as well decreased presence of proinflammatory mediators. PAD4-/- mice were also able to maintain baseline kidney function after Hem/CLP. These data taken together suggest PAD4-mediated NET formation contributes to the mortality associated with shock/sepsis and may play a role in the pathobiology of end organ injury in response to combined hemorrhage plus sepsis. [ABSTRACT FROM AUTHOR]

Epidemiological studies indicate that cigarette smoking (CS) increases the risk and severity of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). The mechanism is not understood, at least in part because of lack of animal models that reproduce the key features of the CS priming process. In this study, using two strains of mice, we characterized a double-hit mouse model of ALI induced by CS priming of injury caused by lipopolysaccharide (LPS). C57BL/6 and AKR mice were preexposed to CS briefly (3 h) or subacutely (3 wk) before intratracheal instillation of LPS and ALI was assessed 18 h after LPS administration by measuring lung static compliance, lung edema, vascular permeability, inflammation, and alveolar apoptosis. We found that as little as 3 h of exposure to CS enhanced LPS-induced ALI in both strains of mice. Similar exacerbating effects were observed after 3 wk of preexposure to CS. However, there was a strain difference in susceptibility to CS priming for ALI, with a greater effect in AKR mice. The key features we observed suggest that 3 wk of CS preexposure of AKR mice is a reproducible, clinically relevant animal model that is useful for studying mechanisms and treatment of CS priming for a second-hitinduced ALI. Our data also support the concept that increased susceptibility to ALI/ARDS is an important adverse health consequence of CS exposure that needs to be taken into consideration when treating critically ill individuals. [ABSTRACT FROM AUTHOR]

Background: Acute respiratory distress syndrome (ARDS) remains a common organ dysfunction in the critically ill patient. Mechanisms for its development have focused on immune mediated causes, aspects of our understanding are not complete, and we lack biomarkers. Design, setting, and subjects: Blood and bronchial alveolar lavage fluid (BAL) from humans (n = 10-13) with ARDS and controls (n = 5-10) as well as a murine model of ARDS (n = 5-6) with controls (n = 6-7) were studied. Methods: ARDS was induced in mice by hemorrhagic shock (day 1) followed by poly-microbial sepsis (day 2). Samples were then collected on the third day after the animals were euthanized. Ex vivo experiments used splenocytes from animals with ARDS cultured with and without soluble programmed death receptor-1 (sPD-1). Results: Levels of sPD-1 are increased in both the serum (11,429.3 pg/mL(SD 2133.3) vs. 8061.4(SD 4187.8), p = 0.036) and bronchial alveolar lavage (BAL) fluid (6,311.1 pg/mL(SD 3758.0) vs. 90.7 pg/mL(SD 202.8), p = 0.002) of humans with ARDS. Similar results are seen in the serum (9396.1 pg/mL(SD 1546.0) vs. 3464.5 pg/mL(SD 2511.8), p = 0.001) and BAL fluid (2891.7 pg/mL(SD 868.1) vs. 1385.9 pg/mL(SD 927.8), p = 0.012) of mice. sPD-1 levels in murine blood (AUC = 1(1-1), p = 0.006), murine BAL fluid (AUC = 0.905(0.717-1.093), p = 0.015), and human BAL (AUC = 1(1-1), p = 0.001) fluid predicted ARDS. To assess the importance of sPD-1 in ARDS, ex vivo experiments were undertaken. BAL fluid from mice with ARDS dampens the TNF-a production compared to cells cultured with BAL lacking sPD-1 (2.7 pg/mL(SD 3.8) vs. 52.38 pg/mL(SD 25.1), p = 0.002). Conclusions: This suggests sPD-1 is elevated in critical illness and may represent a potential biomarker for ARDS. In addition, sPD-1 has an anti-inflammatory mechanism in conditions of marked stress and aids in the resolution of severe inflammation. sPD-1 could be used to not only diagnose ARDS, but may be a potential therapy. [ABSTRACT FROM AUTHOR]

Recent studies suggest that coinhibitory receptors appear to be important in contributing sepsis-induced immunosuppression. Our laboratory reported that mice deficient in programmed cell death receptor (PD)-1 have increased bacterial clearance and improved survival in experimental sepsis induced by cecal ligation and puncture (CLP). In response to infection, the liver clears the blood of bacteria and produces cytokines. Kupffer cells, the resident macrophages in the liver, are strategically situated to perform the above functions. However, it is not known if PD-1 expression on Kupffer cells is altered by septic stimuli, let alone if PD-1 ligation contributes to the altered microbial handling seen. Here we report that PD-1 is significantly upregulated on Kupffer cells during sepsis. PD-1-deficient septic mouse Kupffer cells displayed markedly enhanced phagocytosis and restoration of the expression of major histocompatibility complex II and CD86, but reduced CD80 expression compared with septic wild-type (WT) mouse Kupffer cells. In response to ex vivo LPS stimulation, the cytokine productive capacity of Kupffer cells derived from PD-1-/- CLP mice exhibited a marked, albeit partial, restoration of the release of IL-6, IL-12, IL-1β, monocyte chemoattractant protein-1, and IL-10 compared with septic WT mouse Kupffer cells. In addition, PD-1 gene deficiency decreased LPS-induced apoptosis of septic Kupffer cells, as indicated by decreased levels of cleaved caspase-3 and reduced terminal deoxynucleotidyl transferase dUTP nick end-labeling-positive cells. Exploring the signal pathways involved, we found that, after ex vivo LPS stimulation, septic PD-1-/- mouse Kupffer cells exhibited an increased Akt phosphorylation and a reduced p38 phosphorylation compared with septicWT mouse Kupffer cells. Together, these results indicate that PD-1 appears to play an important role in regulating the development of Kupffer cell dysfunction seen in sepsis. [ABSTRACT FROM AUTHOR]

Studies imply that intestinal barrier dysfunction is a key contributor to morbid events associated with sepsis. Recently, the co-inhibitory molecule programmed death-ligand1 (PD-L1) has been shown to be involved in the regulation of intestinal immune tolerance and/or inflammation. Our previous studies showed that PD-L1 gene deficiency reduced sepsis-induced intestinal injury morphologically. However, it is not known how PD-L1 expression impacts intestinal barrier dysfunction during sepsis. Here we tested the hypothesis that PD-L1 expressed on intestinal epithelial cells (IECs) has a role in sepsis-induced intestinal barrier dysfunction. To address this, C57BL/6 or PD-L1 gene knockout mice were subjected to experimental sepsis and PD-L1 expression, intestinal permeability and tissue cytokine levels were assessed. Subsequently, septic or nonseptic colonic samples (assigned by pathology report) were immunohistochemically stained for PD-L1 in a blinded fashion. Finally, human Caco2 cells were used for in vitro studies. The results demonstrated that PD-L1 was constitutively expressed and sepsis significantly upregulates PD-L1 in IECs from C57BL/6 mice. Concurrently, we observed increased PD-L1 expression in colon tissue samples from septic patients. PD-L1 gene deficiency reduced ileal permeability and tissue levels of IL-6, TNF-α and MCP-1, and prevented ileal tight junction protein loss compared with WT after sepsis. Comparatively, while Caco2 cell monolayers also responded to inflammatory cytokine stimulation with elevated PD-L1 expression, increased monolayer permeability and altered/decreased monolayer tight junction protein morphology/expression, these changes were reversed by PD-L1 blocking antibody. Together these data indicate that ligation of PD-L1 plays a novel role in mediating the pathophysiology of sepsis-induced intestinal barrier dysfunction. [ABSTRACT FROM AUTHOR]

Chimeric antigen receptor-modified T cell (CAR-T) technology, a promising immunotherapeutic tool, has not been applied specifically to treat liver metastases (LM). While CAR-T delivery to LM can be optimized by regional intrahepatic infusion, we propose that liver CD11b+Gr-1+ myeloid-derived suppressor cells (L-MDSC) will inhibit the efficacy of CAR-T in the intrahepatic space. We studied anti-CEA CAR-T in a murine model of CEA+ LM and identified mechanisms through which L-MDSC expand and inhibit CAR-T function. We established CEA+ LM in mice and studied purified L-MDSC and responses to treatment with intrahepatic anti-CEA CAR-T infusions. L-MDSC expanded threefold in response to LM, and their expansion was dependent on GM-CSF, which was produced by tumor cells. L-MDSC utilized PD-L1 to suppress anti-tumor responses through engagement of PD-1 on CAR-T. GM-CSF, in cooperation with STAT3, promoted L-MDSC PD-L1 expression. CAR-T efficacy was rescued when mice received CAR-T in combination with MDSC depletion, GM-CSF neutralization to prevent MDSC expansion, or PD-L1 blockade. As L-MDSC suppressed anti-CEA CAR-T, infusion of anti-CEA CAR-T in tandem with agents targeting L-MDSC is a rational strategy for future clinical trials. [ABSTRACT FROM AUTHOR]

Background. Severe gram-negative bacterial infections and sepsis are major causes of morbidity and mortality. Dysregulated, excessive proinflammatory cytokine expression contributes to the pathogenesis of sepsis. A CD28 mimetic peptide (AB103; previously known as p2TA) that attenuates CD28 signaling and T-helper type 1 cytokine responses was tested for its ability to increase survival in models of polymicrobial infection and gram-negative sepsis.Methods. Mice received AB103, followed by an injection of Escherichia coli 0111:B4 lipopolysaccharide (LPS); underwent induction E. coli 018:K1 peritonitis induction, followed by treatment with AB103; or underwent cecal ligation and puncture (CLP), followed by treatment with AB103. The effects of AB103 on factors associated with and the lethality of challenge infections were analyzed.Results. AB103 strongly attenuated induction of tumor necrosis factor α and interleukin 6 (IL-6) by LPS in human peripheral blood mononuclear cells. Receipt of AB103 following intraperitoneal injection of LPS resulted in survival among 73% of CD1 mice (11 of 15), compared with 20% of controls (3 of 15). Suboptimal doses of antibiotic alone protected 20% of mice (1 of 5) from E. coli peritonitis, whereas 100% (15 of 15) survived when AB103 was added 4 hours following infection. Survival among mice treated with AB103 12 hours after CLP was 100% (8 of 8), compared with 17% among untreated mice (1 of 6). In addition, receipt of AB103 12 hours after CLP attenuated inflammatory cytokine responses and neutrophil influx into tissues and promoted bacterial clearance. Receipt of AB103 24 hours after CLP still protected 63% of mice (5 of 8).Conclusions. Single-dose AB103 reduces mortality in experimental models of polymicrobial and gram-negative bacterial infection and sepsis, warranting further studies of this agent in clinical trials. [ABSTRACT FROM AUTHOR]

Background: The etiology of sepsis is broad. The peritoneal cavity displays compartmentalization with respect to inflammatory responses, so peripheral blood responses to sepsis of abdominal vs. non-abdominal origin are expected to be divergent. Lymphocytes and invariant natural killer T (iNKT) cells play important roles in survival from sepsis, as they dampen the neutrophil and macrophage responses. We assessed whether circulating iNKT cells display distinct phenotypic profiles depending on the presence of abdominal vs. non-abdominal infection with sepsis.Methods: Patients with sepsis, defined as infection confirmed microbiologically with a systemic inflammatory response syndrome (SIRS), were enrolled prospectively. They were categorized as having either exclusively sepsis of abdominal or exclusively non-abdominal origin. The white blood cell (WBC) count was recorded. Whole-blood staining with monoclonal antibodies to CD3, V-alpha-24 (to identify iNKT cells), and CD69 (marker of early activation) was applied.Results: Of the 53 enrolled patients, 18 had abdominal infection. Pneumonia was the most common non-abdominal type. There was no difference in gender, age, Acute Physiology and Chronic Health Evaluation (APACHE) II score, WBC count, or CD3(+) T cells (7.1%±1.6% vs. 6.5%±0.9%; p=0.75) in the two groups. Patients with abdominal infection had a higher proportion of iNKT cells (2.7%±1.1% vs. 0.89%±0.14%; p=0.032). Correcting for WBC count, this translated into a higher absolute number of iNKT cells (3.4±1.8×10(7)/L vs. 0.74±0.15×10(7)/L; p=0.03). Patients with sepsis of abdominal origin had a lower percentage of CD69(+) iNKT cells (9.1%±3.1% vs. 27.2%±5.8%; p=0.028). In patients in shock vs. those who were not, patients with non-abdominal infection exhibited a greater number of iNKT cells (1.47±0.3 v. 0.62±0.1×10(7)/L; p=0.022) and percentage of activated iNKT cells (53±14.5% vs. 17.9±4.8%; p=0.04). Patients with non-abdominal infection who died had a lower absolute number of activated iNKT cells (0.8±1.2×10(7)/L vs. 0.34±0.1×10(7)/L; p=0.023); however, no such shock or death correlation was noted in patients with sepsis of abdominal origin.Conclusions: Divergent sepsis etiologies display distinct blood iNKT cell population changes. In non-abdominal infection, this difference was associated with septic shock and death. Elucidating the importance and basis for these changes relative to the response to sources of infection will help clarify appropriate diagnosis and management of the patient with sepsis. [ABSTRACT FROM AUTHOR]

Background: The etiology of sepsis is broad. The peritoneal cavity displays compartmentalization with respect to inflammatory responses, so peripheral blood responses to sepsis of abdominal vs. non-abdominal origin are expected to be divergent. Lymphocytes and invariant natural killer T ( iNKT) cells play important roles in survival from sepsis, as they dampen the neutrophil and macrophage responses. We assessed whether circulating iNKT cells display distinct phenotypic profiles depending on the presence of abdominal vs. non-abdominal infection with sepsis. Methods: Patients with sepsis, defined as infection confirmed microbiologically with a systemic inflammatory response syndrome (SIRS), were enrolled prospectively. They were categorized as having either exclusively sepsis of abdominal or exclusively non-abdominal origin. The white blood cell (WBC) count was recorded. Whole-blood staining with monoclonal antibodies to CD3, V-alpha-24 (to identify iNKT cells), and CD69 (marker of early activation) was applied. Results: Of the 53 enrolled patients, 18 had abdominal infection. Pneumonia was the most common non-abdominal type. There was no difference in gender, age, Acute Physiology and Chronic Health Evaluation (APACHE) II score, WBC count, or CD3+ T cells (7.1%±1.6% vs. 6.5%±0.9%; p=0.75) in the two groups. Patients with abdominal infection had a higher proportion of iNKT cells (2.7%±1.1% vs. 0.89%±0.14%; p=0.032). Correcting for WBC count, this translated into a higher absolute number of iNKT cells (3.4±1.8×107/L vs. 0.74±0.15×107/L; p=0.03). Patients with sepsis of abdominal origin had a lower percentage of CD69+ iNKT cells (9.1%±3.1% vs. 27.2%±5.8%; p=0.028). In patients in shock vs. those who were not, patients with non-abdominal infection exhibited a greater number of iNKT cells (1.47±0.3 v. 0.62±0.1×107/L; p=0.022) and percentage of activated iNKT cells (53±14.5% vs. 17.9±4.8%; p=0.04). Patients with non-abdominal infection who died had a lower absolute number of activated iNKT cells (0.8±1.2×107/L vs. 0.34±0.1×107/L; p=0.023); however, no such shock or death correlation was noted in patients with sepsis of abdominal origin. Conclusions: Divergent sepsis etiologies display distinct blood iNKT cell population changes. In non-abdominal infection, this difference was associated with septic shock and death. Elucidating the importance and basis for these changes relative to the response to sources of infection will help clarify appropriate diagnosis and management of the patient with sepsis. [ABSTRACT FROM AUTHOR]

Respiratory burst function of neutrophils is thought to play a pivotal role in the development of pathologies such as indirect (extra-pulmonary) acute lung injury (iALI), as well as sepsis. The current study was conducted to determine the effect of an HIV transactivator of transcription (TAT)-fusion protein containing a soluble N-ethylmaleimide-sensitive factor attachment protein receptor domain from synaptosome-associated protein-23 (SNAP-23) on the shock/sepsis- and sepsis-enhanced neutrophil burst capacity using the clinical relevant two-hit iALI mouse model and the classical cecal ligation and puncture (CLP) septic model. TAT-SNAP-23 significantly decreased the blood neutrophil respiratory burst in vitro, and also in vivo in CLP and hemorrhaged mice. We found that the neutrophil influx to the lung tissue, as measured by myeloperoxidase levels and neutrophil-specific esterase+ cells, was also decreased in the TAT-SNAP-23-treated group. Consistent with this, treatment of TAT-SNAP-23 significantly reduced the disruption of lung tissue architecture and protein concentration of bronchoalveolar lavage fluid in iALI mice compared with vehicle-treated iALI mice. In addition, although TAT-SNAP-23 did not alter the extent of local cytokine/chemokine expression, the in vitro migration capacity of neutrophils was blunted from septic and hemorrhagic mice. These data support our hypothesis that TAT-SNAP-23 reduces neutrophil dysfunction in iALI and sepsis by inhibiting neutrophil respiratory burst. [ABSTRACT FROM AUTHOR]

Background: Inflammatory responses to trauma, especially if exaggerated, drive mortality and morbidities including infectious complications. Geriatric patients are particularly susceptible to profound inflammation. Age-related declines in inflammatory and immune systems are known to occur. Geriatric patients display dampened inflammatory responses to non-critical disease processes. Specific inflammatory responses in critically ill geriatric trauma patients, and how the inflammatory profile associated with subsequent infections or mortality, remain unknown. Methods: Geriatric (≥65 y) and young (18-50 y old) critically ill blunt trauma intensive care unit (ICU) patients were enrolled prospectively. Blood was drawn within 36 h of presentation to measure circulating cytokines including interleukin (IL)-6 (pg/mL), IL-10 (pg/mL), and tumor necrosis factor (TNF)-α (pg/mL) levels. Age, gender, Acute Physiology and Chronic Health Evaluation (APACHE II) score and outcomes were reviewed. Results: Twenty-one young and 29 geriatric critically ill patients were recruited. Groups were comparable in male gender and age-adjusted APACHE II score, but geriatric patients had higher mortality (38% versus 9.5%; p=0.04). Within geriatric trauma patients, the development of a secondary infection was associated with significantly lower presenting IL-6 and IL-10 levels and no difference in TNF-α levels. Furthermore, geriatric patients who died had elevated IL-6 and IL-10 and decreased TNF-α levels compared with geriatric patients who lived. Compared with the young cohort, IL-6 and IL-10 levels were similar between geriatric patients who died and young patients who lived. However, geriatric patients who lived, compared with young patients who lived, had significantly lower IL-6 and IL-10. There was no such relation noted with TNF-α. Conclusions: A lowered inflammatory response in geriatric patients is associated with the development of a subsequent infection. However, geriatric patients exhibiting inflammatory responses as robust as their younger counterparts have increased mortality. Redefining our understanding of an appropriate geriatric inflammatory response to trauma will help future therapy, thereby improving morbidity and mortality. [ABSTRACT FROM AUTHOR]

Highlights: [•] Sepsis is the leading cause of death in critically ill patients and novel therapies are necessary. [•] Immune suppression is frequently associated with sepsis-related deaths. [•] Therapies or immunomodulatory agents that enhance the immune response should be considered. [•] Cytokines and co-inhibitory receptors represent potential immunomodulatory agents. [ABSTRACT FROM AUTHOR]

Abstract: Background: Sepsis is associated with severe immunosuppression, evidenced by loss and dysfunction of CD3+ lymphocytes and γδ-TCR+ T-cells. There is limited data addressing changes in the invariant natural killer T-(iNKT) cell population with sepsis, and whether such changes correlate with clinical outcomes. Specifically, septic geriatric patients have marked mortality. How γδ-TCR+ T-cells and iNKT-cells are altered in the settings of sepsis and advanced age, and how these changes correlate with mortality are unknown. Methods: 49 young (18–50years) and 55 geriatric (>65years) ICU patients with confirmed sepsis were enrolled. Blood was stained with antibodies to detect the percentage and absolute number of CD3+ (T-cells), γδ-TCR+ T-cell, TCR-Vα-24+ (iNKT-cells), and CD69+ (marker of cell activation). Blood from 10 healthy controls was also collected. Results: Septic patients displayed marked leukocytosis, decreased CD3+ lymphocytes, and γδ-TCR+ T-cells, and increased percentage and number of iNKT-cells. Young and geriatric patients had similar degree of leukocytosis, along with percentage, number, and %CD69+ CD3+ T-cell and γδ-TCR+ T-cells; however, percentage, number, and %CD69+ iNKT-cells were most markedly elevated in geriatric patients. Geriatric non-survivors had higher percentage and number of, but decreased %CD69+, iNKT-cells vs survivors. Conclusions: iNKT-cells are increased in sepsis, suggesting that they typify an evolving morbid state. This is most pronounced in geriatric non-survivors, a group demonstrating dysfunctional regulatory iNKT-cell phenotype. [Copyright &y& Elsevier]

Identifying relevant mediators responsible for the pathogenesis during sepsis may lead to finding novel diagnostic and therapeutic targets. Recent studies indicate programmed cell death receptor (PD)-l plays a significant role in the development of immune suppression associated with sepsis. In this study, we determine whether B7-H1, the primary ligand of PD-1, contributes to the pathogenesis of sepsis. We report that B7-H1 is upregulated extensively on various immune cells during sepsis and B7-H1 gene deficiency protects mice from the lethality of sepsis. In terms of the histological development of multiple organ damage and inflammatory cytokine levels in circulation or at infectious site, B7-H 1-deficient mice showed a remarkable reduction in these indices when compared with wild-type mice. However, B7-HI gene-deficient mice did not exhibit a lower bacterial burden when compared with wild-type mice, although they recruited more macrophages and neutrophils into infectious site. In addition, we found that, during sepsis, whereas there were no marked differences affecting ex vivo macrophage cytokine productive capacity between PD-1 and B7-H1 gene-deficient mice, preservation of ex vivo macrophage phagocytic function was only seen in septic PD-1 knockout mouse cells. Finally, higher percentage B7-H1+ neutrophils in peripheral blood correlated not only with higher levels of pro- and antiinflammatory cytokines/chemokines (CCL2, IL-6, CXCL2, KC, TNF-α, and IL-10), but with lethal outcome as well. Together, these results indicate B7-H1 contributes to septic morbidity in fashion distinct from PD-1 and suggest B7-H1 expression on neutrophils could be used as a biomarker of septic severity. [ABSTRACT FROM AUTHOR]

The pathogenesis of acute lung injury and acute respiratory distress syndrome is characterized by sequestration of leukocytes in lung tissue, disruption of capillary integrity, and pulmonary edema. PKCδ plays a critical role in RhoA-mediated endothelial barrier function and inflammatory responses. We used mice with genetic deletion of PKCδ (PKCδ-/-) to assess the role of PKCδ in susceptibility to LPS-induced lung injury and pulmonary edema. Under baseline conditions or in settings of increased capillary hydrostatic pressures, no differences were noted in the filtration coefficients (kf) or wet-to-dry weight ratios between PKCδ-/- and PKCδ-/- mice. However, at 24 h after exposure to LPS, the kf values were significantly higher in lungs isolated from PKCδ-/- than PKCδ-/- mice. In addition, bronchoalveolar lavage fluid obtained from LPS-exposed PKCδ-/- mice displayed increased protein and cell content compared with LPS-exposed PKCδ-/- mice, but similar changes in inflammatory cytokines were measured. Histology indicated elevated LPS-induced cellularity and inflammation within PKCδ-/- mouse lung parenchyma relative to PKCδ-/- mouse lungs. Transient overexpression of catalytically inactive PKCδ cDNA in the endothelium significantly attenuated LPS-induced endothelial barrier dysfunction in vitro and increased kf lung values in PKCδ-/- mice. However, transient overexpression of wild-type PKCδ cDNA in PKCδ-/- mouse lung vasculature did not alter the protective effects of PKCδ deficiency against LPS-induced acute lung injury. We conclude that PKCδ plays a role in the pathological progression of endotoxin-induced lung injury, likely mediated through modulation of inflammatory signaling and pulmonary vascular barrier function. [ABSTRACT FROM AUTHOR]

In TNF-treated cells, TNFR1, TNFR-associated death domain protein (TRADD), Fas-associated death domain protein, and receptor-interacting protein kinase proteins form the signaling complex via modular interaction within their C-terminal death domains. In this paper, we report that the death domain SXXE/D motifs (i.e., S381DHE motif of TNFR1-death domain as well as S215LKD and S296LAE motifs of TRADD-death domain) are phosphorylated, and this is required for stable TNFR1-TRADD complex formation and subsequent activation of NF-κB. Phospho-S215LKD and phospho-S296LAE motifs are also critical to TRADD for recruiting Fas-associated death domain protein and receptor-interacting protein kinase. I?B kinase β plays a critical role in TNFR1 phosphorylation of S381, which leads to subsequent T cell migration and accumulation. Consistently, we observed in inflammatory bowel disease specimens that TNFR1 was constitutively phosphorylated on S381 in those inflammatory T cells, which had accumulated in high numbers in the inflamed mucosa. Therefore, SXXE/D motifs found in the cytoplasmic domains of many TNFR family members and their adaptor proteins may serve to function as a specific interaction module for the α-helical death domain signal transduction. [ABSTRACT FROM AUTHOR]

The article presents a study which determines the therapeutic accessibility of caspase-mediated cell death as key pathomechanism in indirect acute lung injury. It reveals that the single intratracheal instillation of capcase-three small interfering RNA (siRNA) weakened lung apoptosis and inflammation. It suggests that apoptosis of lung epithelial cells is a relevant pathomechanism in the development of hemmorhage-induced indirect septic acute lung injury.

Lymphocytes help determine whether gut epithelial cells proliferate or differentiate but are not known to affect whether they live or die. Here, we report that lymphocytes play a controlling role in mediating gut epithelial apoptosis in sepsis but not under basal conditions. Gut epithelial apoptosis is similar in unmanipulated Rag-1-/- and wild-type (WT) mice. However, Rag-1-/- animals have a 5-fold augmentation in gut epithelial apoptosis following cecal ligation and puncture (CLP) compared to septic WT mice. Reconstitution of lymphocytes in Rag-1-/- mice via adoptive transfer decreases intestinal apoptosis to levels seen in WT animals. Subset analysis indicates that CD4+ but not CD8+, γδ, or B cells are responsible for the antiapoptotic effect of lymphocytes on the gut epithelium. Gut-specific overexpression of Bcl-2 in transgenic mice decreases mortality following CLP. This survival benefit is lymphocyte dependent since gut-specific overexpression of Bcl-2 fails to alter survival when the transgene is overexpressed in Rag-1-/- mice. Further, adoptively transferring lymphocytes to Rag-1-/- mice that simultaneously overexpress gut-specific Bcl-2 results in improved mortality following sepsis. Thus, sepsis unmasks CD4+ lymphocyte control of gut apoptosis that is not present under homeostatic conditions, which acts as a key determinant of both cellular survival and host mortality. [ABSTRACT FROM AUTHOR]

Sepsis, a leading cause of death worldwide, involves concomitant expression of an overzealous inflammatory response and inefficient bacterial clearance. Macrophage function is pivotal to the development of these two aspects during sepsis; however, the mechanisms underlying these changes remain unclear. Here we report that the PD-1 :PD-L pathway appears to be a determining factor of the outcome of sepsis, regulating the delicate balance between effectiveness and damage by the antimicrobial immune response. To this end we observed that PD-1[sup-/-] mice were markedly, protected from the lethality of sepsis, accompanied by a decreased bacterial burden and suppressed inflammatory cytokine response. To the extent that this is a macrophage-specific aspect of the effects of PD-i, we found the following: first, peritoneal macrophages.expressed significantly higher levels of PD-i during sepsis, which was associated with their development of cellular dysfunction; second, when peritoneal macrophages were depleted (using clodronate liposomes) from PD-1[sup-/-] mice, the animals' bactericidal capacity was lowered, their inflammatory cytokine levels were elevated, and protection from septic lethality was diminished; and third, blood monocytes from both septic mice and patients with septic shock shared markedly increased PD-1 levels. Together, these data suggest that PD-1 may not only be a dysfunctional marker/effector of macrophages/moriocytes, but may also be a potential, therapeutic target for designing measures to modulate the innate immune response, thereby preventing the detrimental effects of sepsis. [ABSTRACT FROM AUTHOR]

Sepsis syndrome represents the leading cause of death in intensive care unit. Patients present features consistent with a decline in immune responsiveness potentially contributing to mortality. We investigated whether CD4+CD25+ regulatory T cells (Treg) participate in the induction of lymphocyte anergy after sepsis. Observational study in septic shock patients and experimental study in mice. We took advantage of the recently described flow cytometric gating strategy using the measurement of CD25 and CD127 expressions for monitoring Treg (CD4+CD25+CD127−Foxp3+). In patients the increased circulating Treg percentage significantly correlated with a decreased lympho-proliferative response. In a murine model of sepsis mimicking these observations, the ex vivo downregulation of Foxp3 expression using siRNA was associated with a restoration of this response. The relative increase in circulating Treg might play a role in lymphocyte anergy described after septic shock and represent a standardizable surrogate marker of declining proliferative capacity after sepsis. [ABSTRACT FROM AUTHOR]

In spite of protective ventilatory strategies, Acute Lung Injury (ALI) remains associated with high morbidity and mortality. One reason for the lack of therapeutic options might be that ALI is a co-morbid event associated with a diverse family of diseases and, thus, may be the result of distinct pathological processes. Among them, activated neutrophil- (PMN-) induced tissue injury and epithelial cell apoptosis mediated lung damage represent two potentially important candidate pathomechanisms that have been put forward. Several approaches have been undertaken to test these hypotheses, with substantial success in the treatment of experimental forms of ALI. With this in mind, we will summarize these two current hypotheses of ALI briefly, emphasizing the role of apoptosis in regulating PMN and/or lung epithelial cell responses. In addition, the contribution that Fas-mediated inflammation may play as a potential biological link between lung cell apoptosis and PMN recruitment will be considered, as well as the in vivo application of small interfering RNA (siRNA) as a novel approach to the inhibition of ALI and its therapeutic implications. [ABSTRACT FROM AUTHOR]

Background: Neutrophils are thought to play pivotal roles in eliminating pathogens, and they have also been implicated in end organ dysfunction associated with systemic inflammatory response syndrome (SIRS). Because modulating neutrophil survival and function has been proposed as a therapy for sepsis, it remains critical to determine under which circumstances modulating neutrophil function is efficacious. The aim of this study was to investigate whether sustaining the presence of neutrophils activated by hemorrhagic shock (HEM) would be disadvantageous during subsequent sepsis, ie, inflammation plus infection, or systemic inflammation without infection. Study Design: Transgenic mice, overexpressing the antiapoptotic protein Bcl-2 in a myeloid restricted fashion (Bcl-2my), and controls (C57) were subjected to HEM, followed 24 hours thereafter either by cecal ligation and puncture to induce sepsis, or by intraperitoneal injection of lipopolysaccharide to induce SIRS. Lung injury was assessed by bronchoalveolar lavage fluid protein and histology. Lung, plasma, and liver cytokines were quantified through CBA or ELISA. Results: In sepsis, Bcl-2my had increased lung neutrophil and lower lung bacteria counts compared with C57. This translated into a marked early survival benefit for Bcl-2my. There were no differences between Bcl-2my and C57 with respect to the degree of lung injury or lung and plasma cytokines. In contrast, in SIRS, Bcl-2my exhibited markedly increased acute lung injury and lung and plasma cytokines when compared with C57. Bcl-2my also had a profound survival disadvantage. Conclusions: Whether effects of prolonged survival of hemorrhage-primed neutrophils are beneficial or detrimental is determined by the nature of the second insult. During sepsis, prolonging neutrophil survival is beneficial, enhancing antimicrobial activity. Alternatively, during inflammation without infection, increased organ damage by long-lived neutrophils is detrimental. [Copyright &y& Elsevier]

Reports on cyclooxygenase 2-mediated suppression of macrophage interleukin-12 production after thermal injury. Suppression of postagladin production by cyclooxygenase-2 inhibitor, NS-398; Prevention of the suppression in plasma interleukin-12 level due to NS-398 level.

Studies have indicated that γδ T lymphocytes play an important role in the regulation of immune function and the clearance of intracellular pathogens. We have recently reported that intraepithelial lymphocytes (IEL). which are rich in γδ T cells, within the small intestine illustrated a significant increase in apoptosis and immune dysfunction in mice subjected to sepsis. However, the contribution of γδ T cells to the host response to polymicrobial sepsis remains unclear. In this study. we initially observed that after sepsis induced by cecal ligation and puncture (CLP). there was an increase in small intestinal IEL CD8+ γδ+ T cells in control γδ+/+ mice. Importantly, we subsequently found an increased early mortality in mice lacking γδ T cells (γδ-/- mice) alter sepsis. This was associated with decreases in plasma TNF-α. lL-6, and IL-12 levels in γδ-/- mice compared with γδ+/+ mice after sepsis. In addition, even though in vitro LPS-stimulated peritoneal macrophages showed a reduction in IL-6 and IL-12 release after CLP, these cytokines were less suppressed in macrophages isolated from γδ-/- mice. Alternatively, IL-10 release was not different between septicγδ+/+ and γδ-/- mice. Whereas T helper (Th)1 cytokine release by anti-CD3-stimulated splenocytes was significantly depressed in septic γδ+/+ mice, there was no such depression in γδ-/- mice. However, γδ T cell deficiency had no effect on Th2 cytokine release. These findings suggest that γδ T cells may play a critical role in regulating the host immune response and survival to sepsis, in part by alteration of the level of IEL CD8+γδ+ T cells and through the development of the Th1 response. [ABSTRACT FROM AUTHOR]

Acute lung injury (ALI) is identified with the targeting/sequestration of polymorphonuclear leukocytes (PMN) to the lung. Instrumental to PMN targeting are chemokines [e.g., macrophage inflammatory protein-2 (MIP-2), keratinocyte-derived chemokine (KC), etc.] produced by macrophage, PMN, and other resident pulmonary cells. However, the relative contribution of resident pulmonary macrophages as opposed to PMN in inducing ALI is poorly understood, We therefore hypothesize that depletion of peripheral blood PMN and/or the oblation of a macrophage-mediated PMN chemokine signal (via macrophage deficiency) will reduce the inflammation and ALI observed in mice following hemorrhage (Hem) and subsequent sepsis (CLP) in our murine model of ALI. To examine this we pretreated mice with either 500 µg anti-mouse Gr1 antibody/animal (to deplete PMN) or subjected mice deficient in mature macrophage (B6C3Fe-a/a-CsF1op) to Hem (90 mm at 35 ± 5 mmHg) followed by resuscitation. Twenty-four hours post-Hem, mice were subjected to CLP and killed 24 h later, and lung tissue samples were collected. Our data showed that in the absence of either peripheral blood PMN or mature tissue macrophages there was a suppression of IL-6, KC, and MIP-2 levels in lung tissue from Hem/CLP mice as well as a reduction in PMN influx to the lung and lung injury (bronchoalveolar lavage fluid protein). In contrast, lung tissue IL-10 and TNF-α levels were suppressed in the macrophage-deficient Hem/CLP mice compared with PMN-depleted Hem/CLP mice. Together, these data suggest that both the PMN and the macrophage are required to induce inflammation seen here, however, macrophage not PMN regulate the release of IL-10, independent of local changes in TNF. [ABSTRACT FROM AUTHOR]

Today, sepsis continues to be a growing problem in the critically ill patient population. A number of laboratories have been interested in understanding how changes in immune cell apoptosis during sepsis appear to contribute to septic morbidity. Consistently, it has been found that immune cell apoptosis is altered in a variety of tissue sites and cell populations both in experimental animals and humans. While divergent mediators, such as steroids and TNF, contribute to some of these apoptotic changes, their effects are tissue and cell population selective. Inhibition of FasL–Fas signaling (by either FasL gene deficiency, in vivo gene silencing [siRNA] or with FasL binding protein) protects septic mice from the onset of marked apoptosis and the morbidity/mortality seen in sepsis. Further, this extrinsic apoptosis response appears to utilize aspects of the Bid-induced mitochondrial pathway. This is in keeping with the findings that pan-specific caspase inhibition or the overexpression of Bcl-2 also protect these animals from the sequellae of sepsis. [ABSTRACT FROM AUTHOR]

Objective: The role of signal transducer and activator of transduction (STAT) 4 vs. 6 has been assessed thus far only in a model of high mortality strongly driven by proinflammation alone. Their role in a low-mortality (LD25) model of sepsis remains unclear.Design and Setting: Prospective controlled animal study in a research laboratory.Subjects: STAT4 and STAT6 knockout mice.Interventions: We induced sepsis by cecal ligation and puncture (CLP) or sham CLP in three groups of mice: (a) STAT4-/-, (b) STAT6-/-, (c) BALB/c. Splenic T cells or macrophages were then harvested 24 h after CLP, and their ability to produce cytokines was assessed.Results: Following CLP T-cells from BALB/c mice were suppressed in the ability to release the Th1 cytokines interleukin (IL) 2 and interferon gamma. The release of Th2 cytokine IL-10 was increased. The Th1 response of STAT4-deficient animals was not only markedly lower in shams but was further suppressed by CLP. The Th2 cytokine response was elevated even more than that of the septic BALB/c. This was associated with lower survival than in the BALB/c. STAT6 deficiency resulted in a stronger Th1 response and a suppressed Th2 response to CLP. A similar difference between IL-12 and IL-10 release was seen in macrophages from these mice. Interestingly, while this resulted in improved survival, compared to STAT4-/- mice, the STAT6-/- animals still had a higher mortality than the BALB/c.Conclusions: These data suggest that contributions from both STAT4 driven processes as well as STAT6 responses are needed in a balanced fashion to maximize the animals' ability to survive septic challenge. [ABSTRACT FROM AUTHOR]

Abstract: Neutrophil associated lung injury is identified with a variety of local and systemic priming insults. In vitro studies have shown that TNF-α mediated suppression of neutrophil apoptosis is due to the secretion of interleukin-8 (IL-8), a human chemokine shown to alter neutrophil chemotaxis. Our initial in vitro antibody neutralization studies with neutrophil chemotactic proteins, keratinocyte-derived chemokine (KC) and macrophage inflammatory protein-2α (MIP-2α), mouse IL-8 homologues, indicate that MIP-2α but not KC appears to mediate TNF-α suppression of mouse neutrophil apoptosis. Therefore, we hypothesized that in vivo neutralization of KC or MIP-2α during an initial priming insult would produce differential effects on the extent of lung injury by restoring normal neutrophil apoptotic function. To assess this, mice were hemorrhaged followed with septic challenge at 24h. Antibody against KC or MIP-2α or a nonspecific IgG was given during resuscitation immediately following hemorrhage. Anti-MIP-2α treatment resulted in a significant reduction in lung tissue IL-6 and myeloperoxidase levels. Percentage of neutrophil apoptosis increased significantly in the anti-KC group. Tissue and plasma KC and MIP-2α were reduced in their respective treatment groups. These data suggest that KC and MIP-2α differ in their mediation of neutrophil function (apoptosis and chemotaxis) and contribution to the pathogenesis of lung injury following hemorrhage subsequent to sepsis. [Copyright &y& Elsevier]

Objective and Design: Pulmonary contusion is frequently followed by acute respiratory distress syndrome, pneumonia, and sepsis. However, immunologic alterations of circulating and resident immune cell populations contributing to the posttraumatic immunosuppression are poorly understood. We therefore characterized the influence of pulmonary contusion on peripheral blood mononuclear cells, peritoneal macrophages, splenocytes, and splenic macrophages. To address the significance of the immunosuppression associated with lung contusion, we investigated how the consecutive addition of moderate or severe sepsis affected survival after blunt chest trauma.Subjects: Male C3H/HeN mice (n = 10 per group) were anesthetized and subjected to chest trauma or sham procedure.Measurements: The cytokine release of cultured peripheral blood mononuclear cells, peritoneal macrophages, splenocytes, and splenic macrophages and plasma levels of tumor necrosis factor-alpha and interleukin-6 from those animals were quantified. Sepsis was induced via cecal ligation and puncture 24 hrs after lung contusion.Main Results: Two hours after blunt chest trauma, plasma tumor necrosis factor-alpha and interleukin-6 were markedly increased, as was peripheral blood mononuclear cell cytokine production, lung myeloperoxidase activity, and lung chemokine concentrations. At 24 hrs and, in part, already at 2 hrs, cytokine release from peritoneal macrophages, splenic macrophages, and splenocytes was significantly suppressed. Furthermore, pulmonary contusion when followed by moderate sepsis significantly diminished survival rate when compared with chest trauma or moderate sepsis alone.Conclusions: These results indicate that pulmonary contusion causes severe immunodysfunction of splenocytes, macrophages, and monocytes in different local compartments and systemically. Moreover, this immunosuppression is associated with an increased susceptibility to infectious complications, which results in a decreased survival rate if blunt chest trauma is followed by a septic insult. [ABSTRACT FROM AUTHOR]