Elizabeth G. King

Pathophysiologic mechanisms in septic shock

The systemic inflammatory response that occurs in the septic patient as a result of an infectious insult affects multiple organs and systems, causing numerous physiological derangements. Alterations in phagocytic, lymphocytic and endothelial cell function and immune regulation are evident, leading to heterogeneity in a host’s response to a septic challenge. In addition, the normal hemostatic balance shifts toward a procoagulant state through alterations in tissue factor, antithrombin, protein C and the inhibition of fibinolysis, which can result in thrombus formation and paradoxical hemostatic failure. In an effort to diagnose sepsis and predict outcomes, biomarkers such as C-reactive protein, pro-calcitonin, pro- and anti-inflammatory cytokines have been investigated with varying results. Targeted therapies for sepsis, most notably Xigris (recombinant human activated protein C), have proven unsuccessful and treatment continues to remain reliant on source control, antibiotics and supportive interventions, specifically early goal-directed therapy. This brief review gives an overview of the immunopathologic and coagulopathic alterations that occur in sepsis, soluble inflammatory mediators as potential diagnostic and prognostic biomarkers, and the clinical management of the septic patient.

Location, location, location: cytokine concentrations are dependent on blood sampling site.

ABSTRACT Objective: Considerable breakthroughs in the field of sepsis have been made using animal models. Sepsis exhibits a wide array of derangements that may be evaluated in the blood, including the release of proinflammatory and anti-inflammatory cytokines. The Shock journal adheres to the ARRIVE guidelines regarding reporting in vivo results to allow reproducibility of data findings. It is generally assumed that blood cytokine concentrations collected from typical sampling sites will be similar, but there are no data validating that this is true. The main purpose of the present study was to determine if the location of blood sampling results in cytokine concentration differences following inflammatory insults. Methods: Two different models of acute inflammation were studied. Adult, female ICR (Institute of Cancer Research) mice were injected with Escherichia coli lipopolysaccharide (n = 28) or subjected to cecal ligation and puncture (n = 16). They were killed at early time points following these inflammatory challenges for the collection of blood from the facial vein, retro-orbital sinus, and heart. Additional samples were collected in EDTA and heparin. Plasma cytokines from the same mouse were collected from each sampling site and evaluated by enzyme-linked immunosorbent assay. Clinical chemical parameters including plasma blood urea nitrogen and total protein were also analyzed. Results: Regardless of model, time of collection, or cytokine measured, cytokine values from heart blood were higher than facial vein values from the same mouse. Interleukin (IL-6) collected from the heart relative to the facial vein demonstrated elevated concentrations following injection of lipopolysaccharide. In a similar manner, higher concentrations of IL-6, macrophage inflammatory protein 2, IL-10, and IL-1 receptor antagonist were found in cardiac puncture samples compared with other sampling sites 24 h after sepsis induced by cecal ligation and puncture. Similar differences were not seen when comparing blood urea nitrogen and total protein values from the two different sites. Using plasma IL-6 collected from the heart would incorrectly stratify predicted-to-live mice into the predicted-to-die category. Therefore, a simple linear regression model was developed to correctly restratify mice to their predicted fate. These data demonstrate that proinflammatory and anti-inflammatory cytokine concentrations are dramatically elevated when drawn centrally from the heart compared with collection from peripheral locations such as the facial vein. It is critical for publications to document the sampling location when evaluating plasma cytokines and attempting to compare studies.

Valproic acid mitigates the inflammatory response and prevents acute respiratory distress syndrome in a murine model of Escherichia coli pneumonia at the expense of bacterial clearance.

BACKGROUND Histone deacetylase inhibitors (HDACI) are members of a family of epigenetic modifying agents with broad anti-inflammatory properties. These anti-inflammatory properties may have important therapeutic implications in acute respiratory distress syndrome (ARDS). However, administration of HDACI may create an immunosuppressive environment conducive to bacterial growth. Accordingly, the aim of the current study is to investigate the effect of HDACI valproic acid (VPA) on host inflammatory response and bacterial burden in a murine model of Escherichia coli pneumonia-induced ARDS. METHODS ARDS was induced in male C57BL6 mice (n = 24) by endotracheal instillation of 3 × 106 E. coli. VPA (250 mg/kg) was administered 30 minutes after E. coli instillation in the intervention group. Blood samples were collected at 3 and 6 hours, and animals were sacrificed at 6 hours. Bronchoalveolar lavage (BAL) was performed, and tissue specimens were harvested. Cytokine levels were measured in blood and BAL, and so was transalveolar protein transit. Cell counts and colony forming units were quantified in BAL fluid. RESULTS VPA reduced neutrophil influx into the lungs and local tissue destruction through decreased myeloperoxidase activity. It also ameliorated the pulmonary and systemic inflammatory response. This led to greater bacterial proliferation in the pulmonary parenchyma. CONCLUSION Administration of VPA in a clinically relevant bacterial model of murine ARDS mitigates the host inflammatory response, essentially preventing ARDS, but creates an immunosuppressive environment that favors bacterial overgrowth.

The Role of the Model of End-Stage Liver Disease Score in Predicting Outcomes of Carotid Endarterectomy.

Objectives: The Model of End-Stage Liver Disease (MELD) score has been traditionally utilized to prioritize for liver transplantation; however, recent literature has shown its value in predicting surgical outcomes for patients with hepatic dysfunction. The benefit of carotid endarterectomy in asymptomatic patients is dependent on low perioperative morbidity. Our objective was to use MELD score to predict outcomes in asymptomatic patients undergoing carotid endarterectomy. Methods: Patients undergoing carotid endarterectomy were identified in the National Surgical Quality Improvement Program data sets from 2005 to 2012. The Model of End-Stage Liver Disease score was calculated using serum bilirubin, creatinine, and the international normalized ratio (INR). Patients were grouped into low (<9), moderate (9-14), and high (15+) MELD classifications. The effect of the MELD score on postoperative morbidity and mortality was assessed by multivariable logistic and gamma regressions and propensity matching. Results: There were 7966 patients with asymptomatic carotid endarterectomy identified. The majority 5556 (70%) had a low MELD score, 1952 (25%) had a moderate MELD score, and 458 (5%) had a high MELD score. High MELD score was independently predictive of postoperative death, increased length of stay, need for transfusion, pulmonary complications, and a statistical trend toward increased cardiac arrest/myocardial infarction. The Model of End-Stage Liver Disease score did not affect postoperative stroke, wound complications, or operative time. Conclusion: High MELD score places asymptomatic patients undergoing carotid endarterectomy at a higher risk of adverse outcomes in the 30 days following surgery. This provides further empirical evidence for risk stratification when considering treatment for these patients. Outcomes of medical management or carotid stenting should be investigated in high-risk patients.

Identification of Preoperative Risk Factors for Protracted Length of Stay after Elective EVAR

INTRODUCTION: We showed that in ischemicmuscle, short-term use of chloroquine (CQ), a common drug that inhibits autophagosome fusion with lysosomes, decreases early markers of autophagy, a stressinduced protective mechanism to recycle organelles. We hypothesized that prolonged chloroquine treatment will produce marked inflammation,poor regeneration, anddisrupted angiogenesis aftermuscle ischemia.

Mo1787 Valproic Acid (VPA), a Histone Deacetylase Inhibitor That Reduces Intraabdominal Adhesions Modulates Peritoneal Plasma Extravasation and Genes That Regulate Fibrin Deposition and Stability

Class III PI3K, also known as hVps34, along with its associated regulatory subunit, hVps15 kinase, are critical components of nutrient sensing, and act as upstream factors required for activation of S6K1, a downstream effector of mTOR complex 1 (mTORC1). The hVps34/ hVps15 complex regulates a variety of cellular functions such as intracellular vesicle trafficking. In addition, AMPK regulates the hVps34-containing complex in response to changes in energy state. Neurotensin (NT), a gut hormone produced and stored in N cells of the distal small bowel, has multiple physiologic effects, including facilitation of fatty acid translocation from the intestinal lumen, coordination of gut motility and stimulation of pancreaticobiliary secretion. Since we have previously found that AMPK and mTORC1 positively and negatively regulate NT release, respectively, the purpose of the present study was to investigate whether hVps34 and hVps15 are required in AMPK or mTORC1-mediated secretion. METHODS. i) The human endocrine cell line, BON, was used for all experiments. BON cells synthesize and secrete NT peptide and process the NT peptide in a manner analogous to that of N cells in the small bowel, thus serving as a useful model for enteroendocrine cell secretion. AMPK activation was induced by Aicar or 2-DG, and NT secretion measured using an NT EIA kit. ii) To determine the involvement of hVps34 and hVps15 in AMPK-mediated effects on NT secretion, endogenous expression of hVps34 and hVps15 was inhibited by siRNA-mediated knockdown. Stable BON cell lines overexpressing either the control vector or hVps34/hVps15 (hVps34 and hVps15 are expressed in one vector but regulated by individual promoters) were established. iii) The physical association of hVps34 with AMPK was evaluated by co-immunoprecipitation (co-IP). RESULTS. NT secretion (induced by Aicar or 2-DG) was attenuated in BON cells transfected with siRNAs targeting hVps34 and hVps15 compared to non-targeting control (NTC) siRNA. Overexpression of hVps34/hVps15 increased both basal and Aicarand 2-DG-stimulated NT secretion. Moreover, we detected the physical association of hVps34 with AMPK by co-IP. hVps34 was detected in both AMPKα1and α2-precipitated complexes with increased hVps34 bound in the AMPKα2 complex. CONCLUSIONS. These results identify a novel regulatory mechanism for the hVps34/hVps15 complex in NT peptide secretion, providing a direct connection between AMPK and hVps34 which is independent of mTORC1/S6K1 signaling.