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Significance: Sepsis is a major public health concern, with high mortality and morbidity, especially among patients undergoing trauma. It is characterized by a systemic inflammatory response syndrome (SIRS) occurring in response to infection. Although classically associated with pathogens, many patients with SIRS do not have infection. The variability of the disease course cannot be fully explained by our current understanding of its pathogenesis. Thus, other factors are likely to play key roles in the development and progression of SIRS/sepsis. Recent Advances: Circulating levels of damage-associated molecular patterns (DAMPs) seem to correlate with SIRS/sepsis morbidity and mortality. Of the known DAMPs, those of mitochondrial (mt) origin have been of particular interest, since their DNA (mtDNA) and formyl peptides (mtFPs) resemble bacterial DNA and peptides, and hence, when released, may be recognized as “danger signals.” Critical Issues: mtDAMPs released after tissue injury trigger immune responses similar to those induced by pathogens. Thus, they can result in systemic inflammation and organ damage, similar to that observed in SIRS/sepsis. We will discuss recent findings on the roles of mtDAMPs, particularly regarding the less recognized mtFPs, in the activation of inflammatory responses and development of SIRS/sepsis. Future Directions: There are no established methods to predict the course of SIRS/sepsis, but clinical studies reveal that plasma levels of mtDAMPs may correlate with the outcome of the disease. We propose that non-pathogen-initiated, mtDAMPs-induced SIRS/sepsis events need further studies aimed at early clinical recognition and better treatment of this disease.

Trauma increases susceptibility to secondary bacterial infections. The events suppressing antimicrobial immunity are unclear. Polymorphonuclear neutrophils (PMNs) migrate toward bacteria using chemotaxis, trap them in extracellular neutrophil extracellular traps, and kill them using respiratory burst (RB). We hypothesized that plasma and wound fluids from trauma patients alter PMN function.Volunteer PMNs were incubated in plasma or wound fluids from trauma patients (days 0 and 1, days 2 and 3), and their functions were compared with PMNs incubated in volunteer plasma. Chemotaxis was assessed in transwells. Luminometry assessed total and intracellular RB responses to receptor-dependent and independent stimulants. Neutrophil extracellular trap formation was assessed using elastase assays. The role of tissue necrosis in creating functionally suppressive systemic PMN environments was assessed using a novel pig model where PMNs were incubated in uninjured pig plasma or plasma from pigs undergoing intraperitoneal instillation of liver slurry.Both plasma and wound fluids from trauma patients markedly suppress total PMN RB. Intracellular RB is unchanged, implicating suppression of extracellular RB. Wound fluids are more suppressive than plasma. Biofluids suppressed RB maximally early after injury and their effects decayed with time. Chemotaxis and neutrophil extracellular trap formation were suppressed by biofluids similarly. Lastly, plasma from pigs undergoing abdominal liver slurry instillation suppressed PMN RB, paralleling suppression by human trauma biofluids.Trauma plasma and wound fluids suppress RB and other key PMNs antimicrobial functions. Circulating suppressive signals can be derived from injured or necrotic tissue at wound sites, suggesting a key mechanism by which tissue injuries can put the host at risk for infection.

Background Trauma and sepsis both increase the risk for secondary infections. Injury mobilizes mitochondrial (MT) danger-associated molecular patterns (mtDAMPs) directly from cellular necrosis. It is unknown, however, whether sepsis can cause active MT release and whether mtDAMPs released by sepsis might affect innate immunity. Methods Mitochondrial release from human monocytes (Mo) was studied after LPS stimulation using electron microscopy and using fluorescent video-microscopy of adherent Mo using Mito-Tracker Green (MTG) dye. Release of MTG+ microparticles was studied using flow cytometry after bacterial stimulation by size exclusion chromatography of supernatants with polymerase chain reaction (PCR) for mitochondrial DNA (mtDNA). Human neutrophil (PMN), chemotaxis, and respiratory burst were studied after PMN incubation with mtDNA. Results LPS caused Mo to release mtDAMPs. Electron microscopy showed microparticles containing MT. mtDNA was present both in microvesicles and exosomes as shown by PCR of the relevant size exclusion chromatography bands. In functional studies, PMN incubation with mtDNA suppressed chemotaxis in a dose-dependent manner, which was reversed by chloroquine, suggesting an endosomal, toll-like receptor-9-dependent mechanism. In contrast, PMN respiratory burst was unaffected by mtDNA. Conclusion In addition to passive release of mtDAMPs by traumatic cellular disruption, inflammatory and infectious stimuli cause active mtDAMP release via microparticles. mtDNA thus released can have effects on PMN that may suppress antimicrobial function. mtDAMP-mediated "feed-forward" mechanisms may modulate immune responses and potentially be generalizable to other forms of inflammation. Where they cause immune dysfunction the effects can be mitigated if the pathways by which the mtDAMPs act are defined. In this case, the endosomal inhibitor chloroquine is benign and well tolerated. Thus, it may warrant study as a prophylactic antiinfective after injury or prior sepsis.

Background Trauma causes tissue injury that results in the release of damage associated molecular patterns (DAMPs) and other mediators at the site of injury and systemically. Such mediators disrupt immune system homeostasis and may activate multicellular immune responses with downstream complications such as the development of infections and sepsis. To characterize these alterations, we used time-of-flight mass cytometry to determine how trauma plasma affects normal peripheral blood mononuclear cell (PBMC) activation to gain insights into the kinetics and nature of trauma-induced circulating factors on human immune cell populations. A better understanding of the components that activate cells in trauma may aid in the discovery of therapeutic targets. Methods PBMCs from healthy volunteers were cultured with 5% plasma (healthy, trauma-1day, or trauma-3day) or known DAMPs for 24 h. Samples were stained with a broad immunophenotyping CyTOF antibody panel. Multiplex (Luminex) cytokine assays were used to measure differences in multiple cytokine levels in healthy and trauma plasma samples. Results Plasma from day 1, but not day 3 trauma patients induced the acute expansion of CD11c+ NK cells and CD73+/CCR7+ CD8 T cell subpopulations. Additionally, trauma plasma did not induce CD4+ T cell expansion but did cause a phenotypic shift towards CD38+/CCR7+ expressing CD4+ T cells. Multiplex analysis of cytokines by Luminex showed increased levels of IL-1RA, IL-6 and IL-15 in trauma-1day plasma. Similar to trauma day 1 plasma, PBMC stimulation with known DAMPs showed activation and expansion of CD11c+ NK cells. Conclusions We hypothesized that circulating factors in trauma plasma would induce phenotypic activation of normal human immune cell subsets. Using an unbiased approach, we identified specific changes in immune cell subsets that respond to trauma plasma. Additionally, CD11c+ NK cells expanded in response to DAMPs and LPS, suggesting they may also be responding to similar components in trauma plasma. Collectively, our data demonstrate that the normal PBMC response to trauma plasma involves marked changes in specific subsets of NK and CD8+ T cell populations. Future studies will target the function of these trauma plasma reactive immune cell subsets. These findings have important implications for the field of acute traumatic injuries.

Heme is an iron-protoporphyrin complex with an essential physiologic function for all cells, especially for those in which heme is a key prosthetic group of proteins such as hemoglobin, myoglobin, and cytochromes of the mitochondria. However, it is also known that heme can participate in pro-oxidant and pro-inflammatory responses, leading to cytotoxicity in various tissues and organs such as the kidney, brain, heart, liver, and in immune cells. Indeed, heme, released as a result of tissue damage, can stimulate local and remote inflammatory reactions. These can initiate innate immune responses that, if left uncontrolled, can compound primary injuries and promote organ failure. In contrast, a cadre of heme receptors are arrayed on the plasma membrane that is designed either for heme import into the cell, or for the purpose of activating specific signaling pathways. Thus, free heme can serve either as a deleterious molecule, or one that can traffic and initiate highly specific cellular responses that are teleologically important for survival. Herein, we review heme metabolism and signaling pathways, including heme synthesis, degradation, and scavenging. We will focus on trauma and inflammatory diseases, including traumatic brain injury, trauma-related sepsis, cancer, and cardiovascular diseases where current work suggests that heme may be most important.

The neutrophil NADPH oxidase produces both intracellular and extracellular reactive oxygen species (ROS). Although oxidase activity is essential for microbial killing, and ROS can act as signaling molecules in the inflammatory process, excessive extracellular ROS directly contributes to inflammatory tissue damage, as well as to cancer progression and immune dysregulation in the tumor microenvironment. How specific signaling pathways contribute to ROS localization is unclear. Here we used a systems pharmacology approach to identify the specific Class I PI3-K isoform p110β, and PLD1, but not PLD2, as critical regulators of extracellular, but not intracellular ROS production in primary neutrophils. Combined crystallographic and molecular dynamics analysis of the PX domain of the oxidase component p47phox, which binds the lipid products of PI 3-K and PLD, was used to clarify the membrane-binding mechanism and guide the design of mutant mice whose p47phox is unable to bind 3-phosphorylated inositol phospholipids. Neutrophils from these K43A mutant animals were specifically deficient in extracellular, but not intracellular, ROS production, and showed increased dependency on signaling through the remaining PLD1 arm. These findings identify the PX domain of p47phox as a critical integrator of PLD1 and p110β signaling for extracellular ROS production, and as a potential therapeutic target for modulating tissue damage and extracellular signaling during inflammation.

Infection is a common complication of major trauma that causes significantly increased morbidity and mortality. The mechanisms, however, linking tissue injury to increased susceptibility to infection remain poorly understood. To study this relationship, we present a potentially novel murine model in which a major liver crush injury is followed by bacterial inoculation into the lung. We find that such tissue trauma both impaired bacterial clearance and was associated with significant elevations in plasma heme levels. While neutrophil (PMN) recruitment to the lung in response to Staphylococcus aureus was unchanged after trauma, PMN cleared bacteria poorly. Moreover, PMN show > 50% less expression of TLR2, which is responsible, in part, for bacterial recognition. Administration of heme effectively substituted for trauma. Finally, day 1 trauma patients (n = 9) showed similar elevations in free heme compared with that seen after murine liver injury, and circulating PMN showed similar TLR2 reduction compared with volunteers (n = 6). These findings correlate to high infection rates.

Significance Septic shock commonly leads to multiorgan injury both directly via tissue inflammation and secondarily via hypoperfusion, but both can result in mitochondrial N-formyl peptide (mtFP) release into the circulation. However, no studies have evaluated the role of circulating mtFPs during septic shock. We found that a relatively high plasma nicotinamide adenine dinucleotide dehydrogenase subunit-6 (the most potent human mtFP) level was independently associated with the development of secondary infection in patients with septic shock and that the increased susceptibility to secondary infection is partly attributed to the suppression of polymorphonuclear leukocyte (PMN) chemotaxis by mtFP occupancy of formyl peptide receptor-1. Incorporation of these findings into therapeutic strategies may improve clinical outcomes in septic shock patients by preventing PMN chemotactic anergy., Secondary infections typically worsen outcomes of patients recovering from septic shock. Neutrophil [polymorphonuclear leukocytes (PMNs)] migration to secondarily inoculated sites may play a key role in inhibiting progression from local bacterial inoculation to secondary infection. Mitochondrial N-formyl peptide (mtFP) occupancy of formyl peptide receptor-1 (FPR1) has been shown to suppress PMN chemotaxis. Therefore, we studied the association between circulating mtFPs and the development of secondary infection in patients with septic shock. We collected clinical data and plasma samples from patients with septic shock admitted to the intensive care unit for longer than 72 h. Impacts of circulating nicotinamide adenine dinucleotide dehydrogenase subunit-6 (ND6) upon clinical outcomes were analyzed. Next, the role of ND6 in PMN chemotaxis was investigated using isolated human PMNs. Studying plasma samples from 97 patients with septic shock, we found that circulating ND6 levels at admission were independently and highly associated with the development of secondary infection (odds ratio = 30.317, 95% CI: 2.904 to 316.407, P = 0.004) and increased 90-d mortality (odds ratio = 1.572, 95% CI: 1.002 to 2.465, P = 0.049). In ex vivo experiments, ND6 pretreatment suppressed FPR1-mediated PMN chemotactic responses to bacterial peptides in the presence of multiple cytokines and chemokines, despite increased nondirectional PMN movements. Circulating mtFPs appear to contribute to the development of secondary infection and increased mortality in patients with septic shock who survive their early hyperinflammatory phase. The increased susceptibility to secondary infection is probably partly mediated by the suppression of FPR1-mediated PMN chemotaxis to secondary infected sites.

Background Trauma induces neutrophil migration toward injury sites, both initiating wound healing and protecting against local bacterial infection. We have previously shown that mitochondrial formyl peptides (mtFPs) released by injured tissues act as chemoattractants by ligating neutrophil (PMN) formyl peptide receptor 1 (FPR1). But this process can also internalize multiple neutrophil chemoattractant receptors and thus might limit neutrophil migration to the lung in response to bacteria. Our objective was to better understand susceptibility to pneumonia after injury and thus find ways to reverse it. Methods and results We modeled the alveolar chemotactic environment in pulmonary infections by incubating Staphylococcus aureus or Escherichia coli with peripheral blood mononuclear cells (PBMC). Survey of the chemotactic mediators in the resultant conditioned media (CM) showed multiple potent chemoattractants. Pretreating PMN with mtFPs to mimic injury potently reduced net migration towards CM and this net effect was mostly reversed by an FPR1 antagonist. Using an established mouse model of injury-dependent lung infection, we then showed simple instillation of exogenous unstimulated human neutrophils into the airway resulted in bacterial clearance from the lung. Conclusion Injury-derived mtFPs suppress global PMN localization into complex chemotactic environments like infected alveoli. Transplantation of naive exogenous human neutrophils into the airway circumvents that pathologic process and prevents development of post-traumatic pneumonia without injury noted to the recipients.

OBJECTIVES Sepsis and sterile both release "danger signals' that induce the systemic inflammatory response syndrome (SIRS). So differentiating infection from SIRS can be challenging. Precision diagnostic assays could limit unnecessary antibiotic use, improving outcomes. METHODS After surveying human leukocyte cytokine production responses to sterile damage-associated molecular patterns (DAMPs), bacterial pathogen-associated molecular patterns, and bacteria we created a multiplex assay for 31 cytokines. We then studied plasma from patients with bacteremia, septic shock, "severe sepsis," or trauma (ISS ≥15 with circulating DAMPs) as well as controls. Infections were adjudicated based on post-hospitalization review. Plasma was studied in infection and injury using univariate and multivariate means to determine how such multiplex assays could best distinguish infective from noninfective SIRS. RESULTS Infected patients had high plasma interleukin (IL)-6, IL-1α, and triggering receptor expressed on myeloid cells-1 (TREM-1) compared to controls [false discovery rates (FDR)

BACKGROUND: Advanced cancer causes necrosis and releases damage-associated molecular patterns (DAMPs). Mitochondrial DAMPs activate neutrophils, including generation of neutrophil extracellular traps (NETs), which are injurious, thrombogenic, and implicated in metastasis. We hypothesised that extracellular mitochondrial DNA (mtDNA) in ascites from patients with epithelial ovarian cancer (EOC) would correlate with worse outcomes. METHODS: Banked ascites supernatants from patients with newly diagnosed advanced EOC were analysed for mtDNA, neutrophil elastase, and activation of healthy donor neutrophils and platelets. TCGA was mined for expression of SELP and ELANE. RESULTS: The highest quartile of ascites mtDNA correlated with reduced progression-free survival (PFS) and a higher likelihood of disease progression within 12-months following primary surgery (n = 68, log-rank, p = 0.0178). NETs were detected in resected tumours. Ascites supernatants chemoattracted neutrophils, induced NETs, and activated platelets. Ascites exposure rendered neutrophils suppressive, based on abrogation of ex vivo stimulated T cell proliferation. Increased SELP mRNA expression correlated with worse overall survival (n = 302, Cox model, p = 0.02). CONCLUSION: In this single-centre retrospective analysis, ascites mtDNA correlated with worse PFS in advanced EOC. Mitochondrial and other DAMPs in ascites may activate neutrophil and platelet responses that facilitate metastasis and obstruct anti-tumour immunity. These pathways are potential prognostic markers and therapeutic targets.

This is a recommended management algorithm from the Western Trauma Association addressing the management of adult patients with abdominal stab wounds. Because there is a paucity of published prospective randomized clinical trials that have generated Class I data, these recommendations are based primarily on published observational studies and expert opinion of Western Trauma Association members. The algorithm and accompanying comments represent a safe and sensible approach that can be followed at most trauma centers. We recognize that there will be patient, personnel, institutional, and situational factors that may warrant or require deviation from the recommended algorithm. We encourage institutions to use this as a guideline to develop their own local protocols.

In all multicellular organisms, immediate host responses to both sterile and infective threat are initiated by very primitive systems now grouped together under the general term 'danger responses'. Danger signals are generated when primitive 'pattern recognition receptors' (PRR) encounter activating 'alarmins'. These molecular species may be of pathogenic infective origin (pathogen-associated molecular patterns) or of sterile endogenous origin (danger-associated molecular patterns). There are many sterile and infective alarmins and there is considerable overlap in their ability to activate PRR, but in all cases the end result is inflammation. It is the overlap between sterile and infective signals acting via a relatively limited number of PRR that generally underlies the great clinical similarity we see between sterile and infective systemic inflammatory responses. Mitochondria (MT) are evolutionarily derived from bacteria, and thus they sit at the crossroads between sterile and infective danger signal pathways. Many of the molecular species in mitochondria are alarmins, and so the release of MT from injured cells results in a wide variety of inflammatory events. This paper discusses the known participation of MT in inflammation and reviews what is known about how the major.

Atrial fibrillation (AF) is the most frequent complication of surgery performed on cardiopulmonary bypass (CPB) and recent work associates CPB with postoperative inflammation. We have shown that all tissue injury releases mitochondrial damage associated molecular patterns (mtDAMPs) including mitochondrial DNA (mtDNA). This can act as a direct, early activator of neutrophils (PMN), eliciting a systemic inflammatory response syndrome (SIRS) while suppressing PMN function. Neutrophil Extracellular Traps (NETs) are crucial to host defence. They carry out NETosis wherein webs of granule proteins and chromatin trap and kill bacteria. We hypothesised that surgery performed on CPB releases mtDAMPs into the circulation. Molecular patterns thus mobilised during CPB might then participate in the pathogenesis of SIRS and predict postoperative complications like AF [1].We prospectively studied 16 patients undergoing elective operations on CPB. Blood was sampled preoperatively, at the end of CPB and on days 1-2 postoperatively. Plasma samples were analysed for mtDNA. Neutrophil IL-6 gene expression was studied to assess induction of SIRS. Neutrophils were also assayed for the presence of neutrophil extracellular traps (NETs/NETosis). These biologic findings were then correlated to clinical data and compared in patients with and without postoperative AF (POAF).Mitochondrial DNA was significantly elevated following CPB (six-fold increase post-CPB, p=0.008 and five-fold increase days 1-2, p=0.02). Patients with POAF showed greater increases in mtDNA post-CPB than those without. Postoperative AF was seen in all patients with a ≥2-fold increase of mtDNA (p=0.037 vs.2-fold). Neutrophil IL-6 gene transcription increased postoperatively demonstrating SIRS that was greatest days 1-2 (p=0.039). Neutrophil extracellular trap (NET) formation was markedly suppressed in the post-CPB state.Mitochondrial DNA is released by CPB surgery and is associated with POAF. IL-6 gene expression increases after CPB, demonstrating the evolution of postoperative SIRS. Lastly, cardiac surgery on CPB also suppressed PMN NETosis. Taken together, our data suggest that mtDNA released during surgery on CPB, may be involved in the pathogenesis of SIRS and related postoperative inflammatory events like POAF and infections. Mitochondrial DNA may therefore prove to be an early biomarker for postoperative complications with the degree of association to be determined in appropriately sized studies. If mtDNA is directly involved in cardiac inflammation, mtDNA-induced toll-like receptor-9 (TLR9) signalling could also be targeted therapeutically.

BACKGROUNDNosocomial pneumonias are common in trauma patients and so interventions to prevent and treat nosocomial pneumonia may improve outcomes. Our prior work strongly suggests that tissue injury predisposes to infections like nosocomial pneumonia because mitochondrial debris originating from inj

Copyright © 2019 by the Society of Critical Care Medicine and Wolters Kluwer Health, Inc. All Rights Reserved. Objectives: Trauma predisposes to systemic sterile inflammation (systemic inflammatory response syndrome) as well as infection, but the mechanisms linking injury to infection are poorly understood. Mitochondrial debris contains formyl peptides. These bind formyl peptide receptor-1, trafficking neutrophils to wounds, initiating systemic inflammatory response syndrome, and wound healing. Bacterial formyl peptides, however, also attract neutrophils via formyl peptide receptor-1. Thus, mitochondrial formyl peptides might suppress neutrophils antimicrobial function. Also, formyl peptide receptor-1 blockade used to mitigate systemic inflammatory response syndrome might predispose to sepsis. We examined how mitochondrial formyl peptides impact neutrophils functions contributing to antimicrobial responses and how formyl peptide receptor-1 antagonists affect those functions. Design: Prospective study of human and murine neutrophils and clinical cohort analysis. Setting: University research laboratory and level 1 trauma center. Patients: Trauma patients, volunteer controls. Animal Subjects: C57Bl/6, formyl peptide receptor-1, and formyl peptide receptor-2 knockout mice. Interventions: Human and murine neutrophils functions were activated with autologous mitochondrial debris, mitochondrial formyl peptides, or bacterial formyl peptides followed by chemokines or leukotrienes. The experiments were repeated using formyl peptide receptor-1 antagonist cyclosporin H, “designer” human formyl peptide receptor-1 antagonists (POL7178 and POL7200), or anti-formyl peptide receptor-1 antibodies. Mouse injury/lung infection model was used to evaluate effect of formyl peptide receptor-1 inhibition. Measurements and Main Results: Human neutrophils cytosolic calcium, chemotaxis, reactive oxygen species production, and phagocytosis were studied before and after exposure to mitochondrial debris, mitochondrial formyl peptides, and bacterial formyl peptides. Mitochondrial formyl peptide and bacterial formyl peptides had similar effects on neutrophils. Responses to chemokines and leukotrienes were suppressed by prior exposure to formyl peptides. POL7200 and POL7178 were specific antagonists of human formyl peptide receptor-1 and more effective than cyclosporin H or anti-formyl peptide receptor-1 antibodies. Formyl peptides inhibited mouse neutrophils responses to chemokines only if formyl peptide receptor-1 was present. Formyl peptide receptor-1 blockade did not inhibit neutrophils bacterial phagocytosis or reactive oxygen species production. Cyclosporin H increased bacterial clearance in lungs after injury. Conclusions: Formyl peptides both activate and desensitize neutrophils. Formyl peptide receptor-1 blockade prevents desensitization, potentially both diminishing systemic inflammatory response syndrome and protecting the host against secondary infection after tissue trauma or primary infection.

Trauma induces a complex immune response, requiring a systems biology approach to capture multicellular changes. Using mass cytometry by time-of-flight (CyTOF), we evaluated time-dependent changes in peripheral blood in trauma patients to identify changes correlated with infection.Total leukocytes were prepared via red blood cell lysis using peripheral blood samples from trauma patients with an Injury Severity Score greater than 20 at Days 1, 3, and 5 after injury, and from age- and sex-matched uninjured controls. Cells were stained using a 33-marker immunophenotyping CyTOF panel. Statistics were calculated using one-way analysis of variance with multiple comparisons.The CyTOF staining demonstrated changes in many cell subsets. The mean expression intensity of CD86 on monocytes decreased significantly at all time points after injury. When the patients were stratified based on development of infection, there was a trend to decreased CD86 expression on monocytes of those patients that developed subsequent infection. Based on stratification, we identified significantly increased expression of CD39 on NK cells only in patients that developed an infection.This study used a systems biology approach to identify novel changes in circulating immune cell subsets in trauma patients correlating with post-traumatic infection. Decreased expression of CD86, a costimulatory molecule, on monocytes demonstrates that trauma affects the innate system's ability to control T-cell immunity. We also found that CD39 expression on NK cells increased significantly in patients with subsequent infection. CD39 is a protein that generates adenosine, which has immunosuppressive effects on several immune cell types including NK cells. In summary, our results point to pathways that may be central to second-hit infections and further study to delineate these pathways could be key to generating clinical biomarkers or targeted immune therapies for trauma patients.Prognostic study, level II.

Trauma is the leading cause of death in young adults. The pathogenetic mechanisms resulting in posttraumatic immunosuppression with increased susceptibility to infection remain unclear. Mitochondria (MT) are released by cells after trauma and can generate danger molecules, such as extracellular ATP (eATP). The vascular and immune cell ectonucleotidase CD39 scavenges eATP to generate immunosuppressive derivatives such as adenosine. Here, we examined the role of eATP generated by exogenous mitochondria in modulating the immune response and provoking immunosuppression in the context of experimental pneumonia models. ATP probes and MitoSOX revealed that liver-derived MT generate ATP and ROS ex vivo. When injected into recipient mice, MT isolated from mouse liver induced upregulation of CD39 and CD73 expression on circulating CD8 T cells and promoted immune cell exhaustion. Next, wild-type mice were injected intraperitoneally with liver MT, followed by intratracheal instillation of pathogenic S. aureus. Mice receiving MT were unable to clear bacteria, as demonstrated by elevated CFU counts in the bronchoalveolar lavage, when compared to mice with bacterial instillation alone. Histological analysis confirmed more pronounced lung injury with infiltration of inflammatory neutrophils in mice administered both MT and bacteria, when compared to mice instilled only with bacteria. Lastly, the MT injection with concomitant bacteria administration resulted in loss of lung-derived CD8 T-cells. Our data indicate that ATP generation by exogenous mitochondria boost CD39 expression in circulating CD8 T-cells and drive dysfunctional immune responses in mice that result in increased susceptibility to bacterial infection of the lungs.

Trauma causes inflammation by releasing mitochondria that act as Danger-Associated Molecular Patterns (DAMPs). Trauma also increases susceptibility to infection. Human mitochondria contain 13 N-formyl peptides (mtFPs). We studied whether mtFPs released into plasma by clinical injury induce neutrophil (PMN) inflammatory responses, whether their potency reflects their similarity to bacterial FPs and how their presence at clinically relevant concentration affects PMN function.N-terminal sequences of the 13 mtFPs were synthesized. Changes in human PMN cytosolic Ca concentration ([Ca]i) and chemotactic responses to mtFPs were studied. Sequence similarity of mtFPs to the canonical bacterial peptide f-Met-Leu-Phe (fMLF/fMLP) was studied using the BLOcks SUbstitution Matrix 62 (BLOSUM 62) system. The presence of mtFPs in plasma of trauma patients was assayed by Enzyme-linked immunosorbent assay (ELISA). The effects of the most potent mtFP (ND6) on PMN signaling and function were then studied at ambient clinical concentrations by serial exposure of native PMN to ND6, chemokines and leukotrienes.Five mtFPs (ND6, ND3, ND4, ND5, and Cox 1) induced [Ca]i flux and chemotaxis in descending order of potency. Evolutionary similarity to fMLF predicted [Ca]i flux and chemotactic potency linearly (R = 0.97, R = 0.95). Chemoattractant potency was also linearly related to [Ca]i flux induction (R = 0.92). Active mtFPs appear to circulate in significant amounts immediately after trauma and persist through the first week. The most active mtFP, ND6, suppresses responses to physiologic alveolar chemoattractants (CXCL-1, leukotriene B4) as well as to fMLF where CXCL-1 and leukotriene B4 do not suppress N-formyl peptide receptor (FPR)-1 responses to mtFPs. Prior FPR-1 inhibition rescues PMN from heterologous suppression of CXCR-1 and BLT-1 by mtFPs.The data suggest mtFPs released by injured tissue may attract PMN to trauma sites while suppressing PMN responses to other chemoattractants. Inhibition of mtFP-FPR1 interactions might increase PMN recruitment to lung bacterial inoculation after trauma. These findings suggest new paradigms for preventing infections after trauma.Therapeutic, Level IV.

Background Postoperative pneumonia is a major cause of morbidity and mortality following cardiac surgery. The inflammatory response to cardiac surgery has been widely studied, but specific mechanisms for postoperative pneumonia have not been determined. Tranexamic acid is renowned for its effect on bleeding but can also modulate inflammatory processes. Cardiac surgery is known to release mitochondrial DAMPs (mtDAMPs) and is linked to postoperative inflammation and atrial fibrillation. We speculated that mtDAMPs might be related to postoperative pneumonia and that this might be modulated by tranexamic acid. Methods Forty-one (41) patients from the Aspirin and Tranexamic Acid for Coronary Artery Surgery (ATACAS) trial were studied. Levels of mitochondrial DNA, matrix metallopeptidase 9 (MMP-9) and neutrophil elastase (NE) were determined in plasma preoperatively, at 24 and 72 hours post-surgery and correlated with clinical outcome. Results mtDNA was significantly elevated postoperatively in the placebo and tranexamic acid (TXA) groups. Neutrophil elastase increased immediately postoperatively and at 24 hours. MMP-9 was elevated in the placebo group early postoperatively and in the TXA group at the immediate postoperative time point and after 24 hours. Six (6) of the 41 (14.6%) patients subsequently developed pneumonia. mtDNA levels were significantly increased at the early postoperative period and the 24-hour time point in patients with pneumonia. Conclusions Cardiac surgery releases mtDNA, increases MMP-9 and NE and this was not influenced by TXA. Inflammation postoperatively might be linked to pneumonia since mtDNA was further elevated in these patients. Due to the low number of individuals developing pneumonia, further studies are warranted to clearly identify whether TXA impacts on the inflammatory response in postoperative pneumonia.

Trauma is a leading cause of death worldwide with 5.8 million deaths occurring yearly. Almost 40% of trauma deaths are due to bleeding and occur in the first few hours after injury. Of the remaining severely injured patients up to 25% develop a dysregulated immune response leading to multiple organ dysfunction syndrome (MODS). Despite improvements in trauma care, the morbidity and mortality of this condition remains very high. Massive traumatic injury can overwhelm endogenous homeostatic mechanisms even with prompt treatment. The underlying mechanisms driving MODS are also not fully elucidated. As a result, successful therapies for trauma-related MODS are lacking. Trauma causes tissue damage that releases a large number of endogenous damage-associated molecular patterns (DAMPs). Mitochondrial DAMPs released in trauma, such as mitochondrial DNA (mtDNA), could help to explain part of the immune response in trauma given the structural similarities between mitochondria and bacteria. MtDNA, like bacterial DNA, contains an abundance of highly stimulatory unmethylated CpG DNA motifs that signal through toll-like receptor-9 to produce inflammation. MtDNA has been shown to be highly damaging when injected into healthy animals causing acute organ injury to develop. Elevated circulating levels of mtDNA have been reported in trauma patients but an association with clinically meaningful outcomes has not been established in a large cohort. We aimed to determine whether mtDNA released after clinical trauma hemorrhage is sufficient for the development of MODS. Secondly, we aimed to determine the extent of mtDNA release with varying degrees of tissue injury and hemorrhagic shock in a clinically relevant rodent model. Our final aim was to determine whether neutralizing mtDNA with the nucleic acid scavenging polymer, hexadimethrine bromide (HDMBr), at a clinically relevant time point in vivo would reduce the severity of organ injury in this model. Conclusions: We have shown that the release of mtDNA is sufficient for the development of multiple organ injury. MtDNA concentrations likely peak at different points in the early postinjury phase dependent on the degree of isolated trauma vs combined trauma and hemorrhagic shock. HDMBr scavenging of circulating mtDNA (and nuclear DNA, nDNA) is associated with rescue from severe multiple organ injury in the animal model. This suggests that HDMBr could have utility in rescue from human trauma-induced MODS.

Surgical site infections (SSIs) are important sources of morbidity, prolonged hospital stays, and readmissions, so they have become a major economic burden. We hypothesized that surgical wound assessment by sonography (SWATS) used at the bedside would detect wound fluid collections and that the presence of such collections would predict SSI better than standard clinical examination. If so, SWATS might be used to indicate early intervention that could prevent SSI morbidity.A prospective, single-institution observational study was conducted on adult inpatients following open abdominal surgery for trauma, gastrointestinal pathology, or biliary pathology at high risk (5%) for SSI using traditional wound classifications. After informed consent was obtained, SWATS was performed using a smartphone-based ultrasound system on postoperative Day 2 to 4 and again before discharge or at postoperative Day 30, whichever came first. Primary treating physicians delivered standard wound care and were blinded to SWATS. SSI was diagnosed if treatment was implemented for suspected or documented wound infection by the treating physician. Results were analyzed by χ test and two-sample pooled variance t test where appropriate, with significance set at p0.05.Forty-nine patients were studied. Nineteen patients had peri-incisional fluid collections found by SWATS. Eight of these patients went on to develop an SSI. SSI was significantly associated with the presence of fluid collections on SWATS (p = 0.009). SWATS had a sensitivity of 72.7% (0.43-0.92), a specificity of 71.1% (0.62-0.77), a positive predictive value of 42.1% (0.25-0.53), and a negative predictive value of 90.0% (0.79-0.97).SWATS has a high negative predictive value that may allow it be an effective screening tool for developing SSI in high-risk surgical wounds. SWATS has the potential to be a useful and cost-effective adjunct to the clinician by objectively suggesting need for early therapy. Further study with larger sample sizes and randomized, SWATS-based interventions are required to validate this small study and determine its place in clinical care.Diagnostic study, level IV.

No known biologic mechanisms link tissue injury with pneumonia (PNA). Neutrophils (PMNs) are innate immune cells that clear bacteria from the lung by migration toward chemoattractants and killing bacteria in neutrophil extracellular traps (NETs). We predicted that tissue injury would suppress PMN antimicrobial function in the lung. We have also shown that mitochondria-derived damage-associated molecular pattern molecules from the bone can alter PMN phenotype and so hypothesized that formyl peptides (FPs) from fractures predispose to PNA by suppressing PMN activity in the lung.Animal studies involved the following. (1) Rats were divided into three groups (10 per condition) as follows: (a) saline injection in the thigh (b) Staphylococcus aureus (SA, 3 × 10) injected intratracheally, or (c) pseudofracture (PsFx; bone supernatant injected in the thigh) plus intratracheally injected SA. (2) Rats were divided into four groups as follows: (a) control, (b) pulmonary contusion (PC), (c) PsFx, and (d) PC + PsFx. Bronchoalveolar lavage was performed 16 hours later. Clinical studies involved the following. (3) Human bone supernatant was assayed for its FP-receptor (FPR) stimulation. (4) Trauma patients' PMN (n = 32; mean ± SE Injury Severity Score [ISS], 27 ± 10) were assayed for chemotaxis (CTX) or treated with Phorbol 12-myristate 13-acetate (PMA, Phorbol ester) and analyzed for NET formation.In the animal studies, (1) SA was rapidly cleared by the uninjured mice and PsFx markedly suppressed lung bacterial clearance (p0.01). (2a) PC induces PMN traffic to the lung, but PsFx decreases PC-induced PMN traffic (p0.01). (2b) SA increased bronchoalveolar lavage PMN, and PsFx decreased that influx (p0.01). In the clinical studies, (3) bone supernatant activates PMN both via FPR-1 and FPR-2. (4) Trauma decreases PMN CTX to multiple chemokines. Circulating PMNs show NETs spontaneously after trauma, but maximal NET formation is markedly attenuated.Fractures may decrease lung bacterial clearance because FP suppresses PMN CTX to other chemoattractants via FPR-1/2. Trauma activates NETosis but suppresses maximal NETosis. Fractures decrease lung bacterial clearance by multiple mechanisms. PNA after fractures may reflect damage-associated molecular pattern-mediated suppression of PMN antimicrobial function in the lung.

Trauma is the sixth leading cause of death worldwide, and is a serious public health problem with major social and economic costs. Local injury initiates an inflammatory cascade leading to local inflammation. More extensive injury can lead to systemic inflammation. Simultaneously though, immune-suppression develops and enhances the risk of infection in severely injured patients (1). Thus trauma patients are at high risk of infection both because physical barriers to tissue inoculation are disrupted and because of impaired host defense against bacterial inoculation (2,3) Thus infection is a leading cause of death after trauma. (2) Blunt chest trauma is common and is an important contributor to 10% to 30% of adult trauma deaths. (4) Chest trauma is commonly accompanied by injury to other organ systems. Abdominal trauma is frequently associated with chest trauma, and is an important factor affecting mortality. (5) Pneumonia is the most common infection complicating chest trauma and is highly related to mortality. (6) Furthermore, pneumonia is the most common infectious complication in multiple trauma patients as a whole with an incidence reaching 30% after severe trauma. (7) Despite the critical association between chest trauma and chest infections in the trauma population, no basic biologic mechanisms have been advanced to explain the association of injury with pneumonia or the high morbidity and mortality of pneumonia after major trauma. Rather, associated findings like ‘splinting’ and ‘failure to breathe deeply’ have been causally implicated without rigorous scientific support. Our previous studies have shown that cellular disruption by trauma releases mitochondrial debris (MTD) into the circulation that is rich in damage associated molecular patterns (DAMPs). These mitochondrial DAMPs show evolutionarily conserved similarities to bacterial Pathogen Associated Molecular Patterns (PAMPs). Thus they can initiate inflammation by signaling through innate immune pathways that create a sepsis-like state. (8–10) Sepsis however, does not necessarily lead directly to lung injury. (11) Another important phenomena we have observed is that is that MTD released by injured tissues attracts neutrophils. This is mediated at least in part by formyl peptides (FP) that act on formyl peptide receptors like FPR1. (10,12) Formyl peptides are typical of bacteria, but are also found in mitochondria. In addition to being neutrophil chemoattractants FP activate mononuclear cells releasing further chemokines and lipid chemoattractants. (13) We hypothesized that MTD released by injured tissue could suppress pulmonary immune responses by diverting neutrophils from the lung and or altering PMN function, thus potentially leaving the lung susceptible to infection

Trauma is currently the leading cause of death in young adults, in some cases due to infection as a consequence of acquired immune suppression. The pathogenesis for this is poorly understood. Extracellular ATP released from cells during injury serves as a danger molecule, but is rapidly converted to AMP by the ectonucleotidase CD39; AMP is then hydrolyzed to immunosuppressive adenosine by CD73 ecto-5’-nucleotidase. Here, we studied the impact of purinergic signaling in trauma patients over time (day 0/1 after trauma (D1) vs day 2 after trauma (D2) vs controls undergoing elective surgery). We noted higher expression of Adenosine A2A- and A2B- receptor mRNA levels in blood PBMCs on D2 and later, when compared to D1 trauma patients and control samples. Analyses of BAL-derived mononuclear cells revealed decreases in CD39 activity in D1 trauma patients and marked decreases in CD73 activity in D2 trauma patients, when compared to controls. Notably, there was increased CD39 and CD73 expression in PBMC-derived CD8 T-cells of trauma patients, suggesting these cells as the prominent subset involved in the purinergic signaling during trauma. Importantly, CD39+CD8+cells from trauma patients displayed features of “immune exhaustion” phenotype (i.e. high PD-1 and Tim-3 levels) and exhibited less cytotoxicity. We conclude that the early phase after trauma is initially characterized by heightened systemic inflammation with boosted ATP-mediated signaling, linked with loss of CD39 activity. This is followed by an immunosuppressive phase characterized by enhanced adenosinergic signaling and by increase in exhausted CD39+CD8+cells, which might impair the innate immune responses and lead to increased susceptibility to infections in trauma patients.

Background: Phlegmonous gastritis is a rare and highly lethal primary bacterial infection of the stomach. The pathogenesis of this disease is understood poorly and no detailed description of its associated findings on computed tomography has been reported. Methods: Case report and literature review. Case Report: The authors describe an 84-year-old male with phlegmonous gastritis presenting as an abdominal catastrophe with portal venous pneumatosis observed on computed tomography. Conclusion: The association of portal venous air and related computed tomographic findings suggesting compromise of the gastric wall should be regarded with suspicion, and the possibility of phlegmonous gastritis should be entertained. Broad-spectrum antibiotic coverage should be instituted. Gram stain of the tissues of the stomach wall may help direct antibiotic therapy toward streptococcal infections as opposed to polymicrobial processes.

Recruitment of neutrophils and release of reactive oxygen species are considered to be major pathogenic components driving acute lung injury (ALI). However, NADPH oxidase, the major source of reactive oxygen species in activated phagocytes, can paradoxically limit inflammation and injury. We hypothesized that NADPH oxidase protects against ALI by limiting neutrophilic inflammation and activating Nrf2, a transcriptional factor that induces antioxidative and cytoprotective pathways. Our objective was to delineate the roles of NADPH oxidase and Nrf2 in modulating acute lung inflammation and injury in clinically relevant models of acute gastric aspiration injury, a major cause of ALI. Acid aspiration caused increased ALI (as assessed by bronchoalveolar lavage fluid albumin concentration) in both NADPH oxidase–deficient mice and Nrf2−/− mice compared with wild-type mice. NADPH oxidase reduced airway neutrophil accumulation, but Nrf2 decreased ALI without affecting neutrophil recovery. Acid injury resulted in a 120-fold increase in mitochondrial DNA, a proinflammatory and injurious product of cellular necrosis, in cell-free bronchoalveolar lavage fluid. Pharmacologic activation of Nrf2 by the triterpenoid 1-[2-cyano-3-,12-dioxooleana-1,9 (11)-dien-28-oyl]imidazole limited aspiration-induced ALI in wild-type mice and reduced endothelial cell injury caused by mitochondrial extract–primed human neutrophils, leading to the conclusion that NADPH oxidase and Nrf2 have coordinated, but distinct, functions in modulating inflammation and injury. These results also point to Nrf2 as a therapeutic target to limit ALI by attenuating neutrophil-induced cellular injury.

Trauma remains the main cause of death for both civilians and those in uniform. Trauma-associated coagulopathy is a complex process involving inflammation, coagulation, and platelet dysfunction. It is unknown whether activation of complement, which occurs invariably in trauma patients, is involved in the expression of trauma-associated coagulopathy. We designed a prospective study in which we enrolled 40 trauma patients and 30 healthy donors upon arrival to the emergency department of BIDMC. Platelets from healthy individuals were incubated with sera from trauma patients and their responsiveness to a thrombin receptor-activating peptide was measured using aggregometry. Complement deposition on platelets from trauma patients was measured by flow cytometry. Normal platelets displayed hypoactivity after incubation with trauma sera even though exposure to trauma sera resulted in increased agonist-induced calcium flux. Depletion of complement from sera further blocked activation of hypoactive platelets. Conversely, complement activation increased aggregation of platelets. Platelets from trauma patients were found to have significantly higher amounts of C3a and C4d on their surface compared with platelets from controls. Depletion of complement (C4d, C3a) reversed the ability of trauma sera to augment agonist-induced calcium flux in donor platelets. Our data indicate that complement enhances platelet aggregation. Despite its complement content, trauma sera render platelets hypoactive and complement depletion further blocks activation of hypoactive platelets. The defect in platelet activation induced by trauma sera is distal to receptor activation since agonist-induced Ca2+ flux is elevated in the presence of trauma sera owing to complement deposition.

Elderly falls are associated with long hospital stays, major morbidity, and mortality. We sought to examine the fate of patients ≥75 years of age admitted after falls.We reviewed all fall admissions in 2008. Causes, comorbidities, injuries, procedures, mortality, readmission, and costs were analyzed.Seven hundred eight patients ≥75 years old were admitted after a fall, with 89% being simple falls. Short-term mortality was 6%. Male sex, atrial fibrillation, acute myocardial infarction, congestive heart failure (CHF), intracranial hemorrhage, hospital-acquired pneumonia, trigger events, Clostridium difficile, and intubation were predictors of death (P.05). Thirty-day readmission occurred in 14%; CHF, craniotomy, and acute renal failure were predictive. The median cost of hospitalization was $11,000 with cardiac disease, anemia, major orthopedic and neurosurgical procedures, pneumonia, and intubation as predictive.Simple falls in the elderly have high morbidity, mortality, and costs. Methodologies for prevention are warranted and should be studied intensively.

Medical technology has benefited many types of patients, but trauma care has arguably benefited more from technologic development than almost any other field.A literature review to identify key technological advances in the care of trauma patients was performed.The advances in trauma care are in great measure due to the integration of many different systems. Medical technology impacts care in the field at the site of the trauma, in the transport to trauma facilities, and care at the trauma center itself. Once at the hospital, technology has impacted care in the trauma bay, intensive care units, the operating room, and in postoperative and long-term care settings. The integration of advancements, however, needs to be examined in a careful systematic fashion to insure that patients will actually derive benefit.

Atrial fibrillation prophylaxis with warfarin and strong antiplatelet agent use in cardiovascular diseases has increased the incidence of anticoagulation in the elderly. We studied traumatic intracranial hemorrhage (TICH) in patients ≥55 years of age on anticoagulation and antiplatelet agents in a stable population.We used a Level 1 Trauma Center registry study comparing TICH in patients on anticoagulation drugs during the index periods 1999 to 2000 (T1) and 2007 to 2008 (T2).A total of 526 TICH patients were seen in T1 and T2 (age, 77.6 vs 77.5 years; not significant [NS]), with the rate doubling from 6.2% to 12.3% of all trauma activations (P.01). There was no increase in atrial fibrillation, warfarin use, or CHADS(2) scores in atrial fibrillation patients on anticoagulation therapy. TICH in patients taking antiplatelet agents increased 5-fold (2.2 % vs 10.3%; P .01). Overall TICH mortality rate was the same (12.4% vs 12.2%, NS). TICH mortality among patients on therapeutic warfarin was greater in T1 (26%; P.05), but mortality was similar to TICH in patients not on anticoagulants in T2 (19% vs 12.2%, NS), suggesting treatment improved. Prevalence and mortality of TICH in patients on antiplatelet agents were similar to TICH in patients on warfarin.TICH in patients on anticoagulants is epidemic in patients ≥55 years of age. Despite national trends, our well-served population has not seen an increase in warfarin use for atrial fibrillation. Instead, use of antiplatelet agents has increased and is associated with an increased incidence of TICH.

Hypothesis: Fractures and femoral reaming are associated with lung injury. The mechanisms linking fractures and inflammation are unclear, but tissue disruption might release mitochondria. Mitochondria are evolutionarily derived from bacteria and contain "damage associated molecular patterns" like formylated peptides that can activate immunocytes. We therefore studied whether fracture reaming releases mitochondrial damage associated molecular patterns (MTD) and how MTD act on immune cells. Methods: Femur fracture reamings (FFx) from 10 patients were spun to remove bone particulates. Supernatants were assayed for mitochondrial DNA. Mitochondria were isolated from the residual reaming slurry, sonicated, and spun at 12,000 g. The resultant MTD were assayed for their ability to cause neutrophil (PMN) Ca 2+ transient production, p44/42 MAPK phosphorylation, interleukin-8 release, and matrix metalloproteinase-9 release with and without formyl peptide receptor-1 blockade. Rats were injected with MTD and whole lung assayed for p44/42 activation. Results: Mitochondrial DNA appears at many thousand-fold normal plasma levels in FFx and at intermediate levels in patients' plasma, suggesting release from fracture to plasma. FFx MTD caused brisk PMN Ca 2+ flux, activated PMN p44/42 MAPK, and caused PMN release of interleukin-8 and matrix metalloproteinase-9. Responses to MTD were inhibited by formyl peptide receptor-1 blockade using cyclosporine H or anti-formyl peptide receptor-1. MTD injection caused P44/42 phosphorylation in rat lung. Conclusions: FFx reaming releases mitochondria into the wound and circulation. MTD then activates PMN. Release of damage signals like MTD from FFx may underlie activation of the cytokine cascades known to be associated with fracture fixation and lung injury.

Background: Tissue injury from mechanical trauma modulates innate immunity. The resultant systemic inflammatory response syndrome (SIRS) closely mimics clinical sepsis, and bacterial n-formyl peptides are septic mediators. Similar formyl peptides exist in mitochondria but little is known about their actions on human neutrophils (PMN). Methods: Mitochondria were isolated from rat heptocytes and disrupted. Soluble mitochondrial degradation products (MDP) were used to stimulate human PMN. Cytosolic calcium ([Ca 2+ ] i ) responses to MDP were assayed with and without antibody blockade of formyl peptide receptor 1 (FPR-1) or formyl peptide receptor like-1 (FPRL-1). Chemotaxis toward MDP was assessed in trans-wells. Oxidative burst to MDP was assessed using carboxy-carboxy-2', 7'-dichlorodihydrofluorescein diacetate. Results: MDP caused [Ca 2+ ] i responses similar to those caused by formyl-Met-Leu-Phe. [Ca 2+ ] i responses were completely blocked by anti-FPR-1 antibodies, showing activation occurred via the high-affinity, G-protein-coupled FPR-1 receptor. MDP acted on FPR-1 to give chemotactic responses similar to 10 nM formyl-Met-Leu-Phe. MDP also caused dose-dependent oxidative burst. Conclusion: Formylated mitochondrial proteins are potent immune activators. Acting through the FPR-1 receptor on professional phagocytes, MDP elicits [Ca 2+ ] i release responses and Ca 2+ entry via G-protein-coupled pathways. MDP activates chemotaxis and respiratory burst. Our findings suggest a novel paradigm wherein one root cause of SIRS after trauma may be the release of mitochondrial fragments from mechanically damaged tissues. In this paradigm, mitochondrial debris "alarmins" alter host PMN phenotype, activating or suppressing immunity, predisposing to SIRS, sepsis or organ failure.

Muscle wasting in various catabolic conditions is at least in part regulated by glucocorticoids. Increased calcium levels have been reported in atrophying muscle. Mechanisms regulating calcium homeostasis in muscle wasting, in particular the role of glucocorticoids, are poorly understood. Here we tested the hypothesis that glucocorticoids increase intracellular calcium concentrations in skeletal muscle and stimulate store-operated calcium entry (SOCE) and that these effects of glucocorticoids may at least in part be responsible for glucocorticoid-induced protein degradation. Treatment of cultured myotubes with dexamethasone, a frequently used in vitro model of muscle wasting, resulted in increased intracellular calcium concentrations determined by fura-2 AM fluorescence measurements. When SOCE was measured by using calcium “add-back” to muscle cells after depletion of intracellular calcium stores, results showed that SOCE was increased 15–25% by dexamethasone and that this response to dexamethasone was inhibited by the store-operated calcium channel blocker BTP2. Dexamethasone treatment stimulated the activity of calcium-independent phospholipase A2(iPLA2), and dexamethasone-induced increase in SOCE was reduced by the iPLA2inhibitor bromoenol lactone (BEL). In additional experiments, treatment of myotubes with the store-operated calcium channel inhibitor gadolinium ion or BEL reduced dexamethasone-induced increase in protein degradation. Taken together, the results suggest that glucocorticoids increase calcium concentrations in myocytes and stimulate iPLA2-dependent SOCE and that glucocorticoid-induced muscle protein degradation may at least in part be regulated by increased iPLA2activity, SOCE, and cellular calcium levels.

Inflammation and microvascular thrombosis are interrelated causes of acute lung injury in the systemic inflammatory response syndrome. Neutrophils (polymorphonuclear neutrophil [PMN]) and endothelial cells (EC) activated by systemic inflammatory response syndrome interact to increase pulmonary vascular permeability, but the interactions between PMN and EC are difficult to study. Recently, we reported that sphingosine 1-phosphate is a second messenger eliciting store-operated calcium entry (SOCE) in response to inflammatory agonists in both PMN and EC. Store-operated calcium entry is therefore a target mechanism for the therapeutic modulation of inflammatory PMN-EC interactions. Here, we isolated, modeled, and studied the effects of pharmacologic SOCE inhibition using real-time systems to monitor EC permeability after exposure to activated PMN. We created systems to continuously assess permeability of human pulmonary artery endothelial cells and human microvascular endothelial cells from lung. Endothelial cells show increased permeability after challenge by activated PMN. Such permeability increases can be attenuated by exposure of the cocultures to sphingosine kinase (SK) inhibitors (SKI-2, N,N-dimethylsphingosine [DMS]) or Ca2+ entry inhibitors (Gd3+, MRS-1845). Human microvascular endothelial cells from lung pretreated with SKI-2 or DMS showed decreased permeability when later exposed to activated PMN. Likewise, when PMNs were activated with thapsigargin (TG) in the presence of SKI-2, DMS, Gd, or MRS-1845, their ability to cause EC permeability subsequently was reduced. SKI-2 also inhibited the activation of human pulmonary artery ECs by thrombin. These studies will provide a firm mechanistic foundation for understanding how systemic SOCE inhibition may be used to prevent acute lung injury in vivo.

Organ failure is a common cause of morbidity and mortality in patients sustaining major trauma, and hence, the pathophysiology of trauma-induced organ injury and dysfunction has been an important line of research.1 Based on these trauma studies, it is clear that shock-induced changes and trauma-induced changes in neutrophil activation are involved in the pathogenesis of the adult respiratory distress syndrome and contribute to the development of the multiple organ dysfunction syndrome.1 Likewise, recent work suggests that impaired red blood cell (RBC) deformability, which occurs in sepsis, after trauma, and during shock states,2–4 contributes to the development of multiple organ dysfunction syndrome by impairing tissue microvascular blood flow.5 Consequently, understanding the factors that modulate the magnitude and extent of neutrophil activation and RBC deformability might provide important insights into ways to limit post-trauma organ dysfunction.1 Because gender and sex hormones have been shown to modulate the development of organ injury as well as the immune system in preclinical models of trauma-hemorrhagic shock (T/HS)6–10 and in some but not all clinical studies,11 we have been interested in investigating the effects of gender and sex hormones on T/HS-induced changes in neutrophil and RBC function. Our earlier studies documented that neutrophil activation12 and RBC rigidification13 were reduced in female as opposed to male rats subjected to T/HS and that estrogen played a protective role in these studies. Because the beneficial effects of estrogen (17β-estradiol) seem to occur through high-affinity estrogen receptors (ER), the major goal of this study was to investigate the relative role that each of the two principal ERs (ER-α and -β) played in protecting against trauma-shock-induced RBC dysfunction, as measured by RBC deformability and neutrophil activation. To accomplish this goal, we administered either the ER-α agonist propyl pyrazole triol (PPT) or the ER-β agonist diarylpropiolnitrile (DPN) to ovariectomized (OVX) rats. These agents were chosen as PPT has a 410-fold higher binding affinity preference for ER-α over ER-β,14 whereas DPN exhibits a 70-fold higher binding affinity to ER-β than ER-α.15

Injury causes a systemic inflammatory response syndrome (SIRS) that is clinically much like sepsis. Microbial pathogen-associated molecular patterns (PAMPs) activate innate immunocytes through pattern recognition receptors. Similarly, cellular injury can release endogenous 'damage'-associated molecular patterns (DAMPs) that activate innate immunity. Mitochondria are evolutionary endosymbionts that were derived from bacteria and so might bear bacterial molecular motifs. Here we show that injury releases mitochondrial DAMPs (MTDs) into the circulation with functionally important immune consequences. MTDs include formyl peptides and mitochondrial DNA. These activate human polymorphonuclear neutrophils (PMNs) through formyl peptide receptor-1 and Toll-like receptor (TLR) 9, respectively. MTDs promote PMN Ca(2+) flux and phosphorylation of mitogen-activated protein (MAP) kinases, thus leading to PMN migration and degranulation in vitro and in vivo. Circulating MTDs can elicit neutrophil-mediated organ injury. Cellular disruption by trauma releases mitochondrial DAMPs with evolutionarily conserved similarities to bacterial PAMPs into the circulation. These signal through innate immune pathways identical to those activated in sepsis to create a sepsis-like state. The release of such mitochondrial 'enemies within' by cellular injury is a key link between trauma, inflammation and SIRS.

Background: The development of coagulopathy associated with trauma is a complex process that involves a combination of many factors. It is important to be able to model experimental trauma-related coagulopathy to explore preventative and therapeutic strategies, and numerous models of traumatic coagulopathy have been explored. This systematic review assessed the primary question What are relevant experimental models with which to study early traumatic coagulopathy? and secondary questions on mechanisms. Methods: The author group reviewed 695 abstracts that resulted in 36 articles being fully reviewed by the group. The group identified 12 key studies (grade A) addressing the primary question. A further 10 articles were thought to be relevant but less important (grade B). Eight articles were considered worthwhile publications but not as relevant to the query (grade C), and six articles were considered not relevant after detailed review (grade D). Results: This structured literature review demonstrated a lack of relevant models for human traumatic coagulopathy. We identify challenges in modeling traumatic coagulopathy and limitations to current experimental models and include a proposal for features of an ideal model of traumatic coagulopathy, but recognize that this involves major challenges. Conclusions: Models of traumatic coagulopathy need to more closely resemble human physiology and real-life conditions if they are to influence clinical practice.

Background: Central venous catheter placement is a common procedure in the intensive care unit. However, these devices are not without complications. We describe the first reported case of descending necrotizing mediastinitis secondary to central venous catheterization without evidence of associated vascular perforation. Methods: Case report and literature review. Results: A 24-year-old man developed descending necrotizing mediastinitis after exploratory laparotomy for a gunshot wound. A central venous catheter was presumed to be the source because blood, intraoperative, and catheter tip cultures grew the same Klebsiella organism, and there was no evidence of venous perforation at the initial operation. Conclusions: Prompt recognition, adequate operative drainage, and appropriate antibiotics remain the best treatment for descending necrotizing mediastinitis.

Ca2+ signaling plays an important role in endothelial cell (EC) functions including the regulation of barrier integrity. Recently, the endogenous lipid derivative, sphingosine-1-phosphate (S1P), has emerged as an important modulator of EC barrier function. We investigated the role of endogenously generated S1P in Ca2+ metabolism and barrier function in human umbilical endothelial cells (HUVECs) stimulated by thrombin, histamine, or other agonists. Barrier function was assessed by dextran diffusion through HUVEC monolayers, and Ca2+ transients were measured using a fluoroprobe. Thrombin or histamine increased Ca2+ release from the endoplasmic reticulum (ER) and Ca2+ entry through store-operated channels (SOCs) that was accompanied by increased EC permeability. Inhibition of S1P synthesis by a specific sphingosine kinase inhibitor (SKI) decreased thrombin or histamine-induced increased permeability and decreased Ca2+ entry via SOC in a concentration-dependent fashion. SKI had minuscule effects on thrombin or histamine-induced Ca2+ release from ER. SKI also inhibited thapsigargin or ionomycin-induced Ca2+ entry via SOC without affecting Ca2+ release from the ER. In contrast to the effects of endogenously generated S1P, when S1P was administered externally, it initiated Ca2+ release from ER similar to thrombin and histamine while decreasing EC permeability. These observations indicate that after agonist-induced conditions, endogenously generated S1P functions as a positive modulator of Ca2+ entry via SOC and a mediator of increased cell permeability. In contrast, extracellular exposure to S1P has different signaling mechanisms and effects. Thus, the potential dual roles of endogenous and exogenous S1P on EC function need to be considered in pharmacological studies targeting sphingosine metabolism.

Recent studies associate cholesterol excess and atherosclerosis with inflammation. The link between these processes is not understood, but cholesterol is an important component of lipid rafts. Rafts are thought to concentrate membrane signaling molecules and thus regulate cell signaling through G protein-coupled pathways. We used methyl β-cyclodextrin to deplete cholesterol from polymorphonuclear neutrophil (PMN) rafts and thus study the effects of raft disruption on G protein-coupled Ca2+ mobilization. Methyl β-cyclodextrin had no effect on Ca2+ store depletion by the G protein-coupled agonists platelet-activating factor or fMLP, but abolished agonist-stimulated Ca2+ entry. Free cholesterol at very low concentrations regulated Ca2+ entry into PMN via nonspecific Ca2+ channels in a biphasic fashion. The specificity of cholesterol regulation for Ca2+ entry was confirmed using thapsigargin studies. Responses to cholesterol appear physiologic because they regulate respiratory burst in a proportional biphasic fashion. Investigating further, we found that free cholesterol accumulated in PMN lipid raft fractions, promoting formation and polarization of membrane rafts. Finally, the transient receptor potential calcium channel protein TRPC1 redistributed to raft fractions in response to cholesterol. The uniformly biphasic relationships between cholesterol availability, Ca2+ signaling and respiratory burst suggest that Ca2+ influx and PMN activation are regulated by the quantitative relationships between cholesterol and other environmental lipid raft components. The association between symptomatic cholesterol excess and inflammation may therefore in part reflect free cholesterol- dependent changes in lipid raft structure that regulate immune cell Ca2+ entry. Ca2+ entry-dependent responses in other cell types may also reflect cholesterol bioavailability and lipid incorporation into rafts.

Bone marrow (BM) dysfunction after trauma and hemorrhagic shock (T/HS) results in a decrease in clonogenic growth of BM progenitors through a plasma-mediated process. Although sex hormones have been shown to modulate some end-organ injury after shock, post-T/HS BM dysfunction has only been studied in male animals. Therefore, the present study examines the effects of sex hormones on post-T/HS BM dysfunction by measuring clonogenic growth of BM progenitors in castrated male rats and in ovariectomized and proestrus female rats.Laboratory experiment.University surgical research laboratory.Castrated and noncastrated male and ovariectomized and proestrus female Sprague-Dawley rats.All rats were subjected to either T/HS or sham shock with laparotomy (n = 3-5 per group). At 3 hrs after resuscitation, the rats were killed and plasma and BM mononuclear cells from bilateral femurs were harvested.BM mononuclear cells were cultured for erythroid burst-forming unit and granulocyte-macrophage colony-forming unit colonies to assess the extent of progenitor BM dysfunction. BM from noncastrated male rats subjected to T/HS demonstrated a significant decrease in granulocyte-macrophage colony-forming unit and erythroid burst-forming unit colony formation compared with BM of all the sham shock groups and with the castrated male and both female rat groups subjected to T/HS. In addition, plasma from noncastrated shocked male rats incubated in vitro with BM cells from unmanipulated male rats caused a significant suppression of BM granulocyte-macrophage colony-forming unit and erythroid burst-forming unit colonies compared with plasma from castrated rats subjected to either sham shock with laparotomy or T/HS.The profound BM dysfunction observed in noncastrated male rats after T/HS is not observed in proestrus female rats and castrated male rats. In addition, the in vitro plasma-mediated BM suppression present in male rats after T/HS is also lost in castrated male rats. Sex hormones seem to play a significant role in BM dysfunction after T/HS.

Post-injury multiple organ failure results from an inappropriate, overwhelming immune response to injury. During trauma and hemorrhagic shock (T/HS), mesenteric ischemia causes gut mucosal breakdown with disruption of the intestinal barrier. It has been proposed that this releases the gut microbiota systemically via post-shock mesenteric lymph, engendering infectious complications. Despite extensive investigation, no clear evidence has been presented for gut bacterial translocation after resuscitation from T/HS. However, such previous studies were limited by available technologies. More sensitive methods, such as quantitative polymerase chain reaction (PCR), have since emerged for detection of bacterial presence and danger-associated molecular patterns (DAMPs). Quantitative PCR was applied to post-shock mesenteric lymph (PSML) derived from a rat model of T/HS. No bacterial presence was detected in a series of 12 samples, whereas multiple lymph samples showed presence of DAMPs after T/HS. Thus, we confirmed that bacterial translocation does not exist in PSML following resuscitation from T/HS-associated mesenteric ischemia. However, T/HS does increase the presence of mitochondrial DAMPs in PSML. These results support our current position that PSML elaborates remote organ injury by multiple inflammatory mechanisms, including lipid-mediated pro-inflammatory stimuli, and by contribution from gut-derived DAMPS.

Appropriate control of redox mechanisms are critical for and effective innate immune response, which employs multiple cell types, receptors and molecules that recognize danger signals when they reach the host. Recognition of pathogen-associated pattern molecules (PAMPs) is a fundamental host survival mechanism for efficient elimination of invading pathogens and resolution of the infection and inflammation. In addition to PAMPs, eukaryotic cells contain a plethora of intracellular molecules that are normally secured within the confines of the plasma membrane, but if liberated and encountered in the extracellular milieu can provoke rapid cell activation. These are known as Alarmins or Danger-Associated Molecular Patterns (DAMPs) and can be released actively by cells or passively as a result of sterile cellular injury after trauma, ischemia, or toxin-induced cell rupture. Both PAMPs and DAMPs are recognized by a series of cognate receptors that increase the generation of free radicals and activate specific signaling pathways that result in regulation of a variety of stress response, redox sensitive genes. Multiple mediators released, as cells die include, but are not limited to ATP, hydrogen peroxide, heme, formyl peptides, DNA or mitochondria provide the second signal to amplify immune responses. In this review, we will focus on how sterile and infective stimuli activate the stress response gene heme oxygenase-1 (Hmox1, HO-1), a master gene critical to an appropriate host response that is now recognized as one with enormous therapeutic potential. HO-1 gene expression is regulated in large part by redox-sensitive proteins including but not limited to nrf2. Both PAMPs and DAMPs increase the activation of nrf2 and HO-1. Heme is a powerful pro-oxidant and as such should be qualified as a DAMP. With its degradation by HO-1a molecule of carbon monoxide (CO) is generated that in turn serves as a bioactive signaling molecule. PAMPs such as bacterial endotoxin activate HO-1, and the CO that is generated diffuses into the extracellular milieu where it interacts with bacteria, altering their behavior to increase production of ATP, which then functions as a second signal danger molecule. This two-hit cycle scenario results in efficient and effective activation of host leukocytes to attack and clear bacteria in part via enhanced reactive oxygen species generation. We discuss this intimate communication that occurs between host and bacteria and how these molecules serve as critical regulators of the acute inflammatory response, the overall redox status of the cell, and survival of the host.

Background: Prolonged courses of broad-spectrum antibiotics are often cited as the standard of care for prevention of infective complications of open fractures. The origins of these recommendations are obscure, however, and multi-drug-resistant systemic infections attributable to antibiotic overuse are common life-threatening problems in current intensive care unit practice. Objective: To review systematically the effects of prophylactic antibiotic administration on the incidence of infections complicating open fractures. Data Sources: Computerized bibliographic search of published research and citation review of relevant articles. Study Selection: All published clinical trials claiming to evaluate, or cited elsewhere as being authoritative regarding, the role of antibiotics in open fracture management were identified and then evaluated according to published guidelines for evidence-based medicine. Only small studies (

Bone marrow (BM) suppression occurs following trauma/hemorrhagic shock (T/HS) in experimental animals as well as following severe injury in humans. Although the pathophysiology of BM suppression remains poorly understood, mesenteric lymph is thought to play an important role in T/HS-induced BM suppression; however, the direct effect of mesenteric lymph on BM in vitro has never been studied. In addition, recent studies in rats have also shown that female and castrated male rats are protected against T/HS-induced BM failure. We therefore hypothesized that mesenteric lymph is a source of factor(s) causing direct BM suppression and that the effects of mesenteric lymph are gender dependent. To test this hypothesis, we subjected noncastrated (NC) and castrated (C) male and proestrus female rats to T/HS or trauma sham shock (T/SS). Mesenteric lymph collected 3 h postshock was plated (4% v/v) with BM cells collected from unmanipulated male or female rats for granulocyte-macrophage colony-forming units (CFU-GM) and erythroid burst-forming units (BFU-E) colony growth. The T/HS lymph collected from NC-male rats but not from female rats caused a 50% inhibition of CFU-GM and BFU-E colony growth compared with cells cultured without lymph (P < 0.05 versus all other groups (ANOVA + Tukey). T/HS lymph collected from C-male rats also caused no significant inhibition of CFU-GM and BFU-E colony growth compared with cells cultured without lymph. Female and male BM progenitor cells had a similar response to mesenteric lymph from all groups tested. These results show that mesenteric lymph from NC-male rats suppresses CFU-GM and BFU-E progenitor growth in vitro, whereas the lymph from C-male and female rats did not. The effects of mesenteric lymph were the same regardless of whether the target BM was from male or female rats. The results therefore indicate that BM failure in male rats is directly mediated by factors present within the mesenteric lymph that appear to be modulated by castration, and protection against BM failure in female rats occurs at a systemic rather than a local level. Further studies are needed to elucidate potential therapeutic effects of lymph manipulation in hematopoiesis after injury.