Cystathionine-γ-lyase expression is associated with mitochondrial respiration during sepsis-induced acute kidney injury in swine with atherosclerosis

Sepsis is associated with disturbed glucose metabolism and reduced mitochondrial activity and biogenesis, ultimately leading to multiple organ dysfunction, e.g., acute kidney injury (AKI). Cystathionine-γ-lyase (CSE), the major cardiovascular source of endogenous H2S release, is implicated in the regulation of glucose metabolism and mitochondrial activity through a PGC1α-dependent mechanism, and critical for kidney function. Atherosclerosis is associated with mitochondrial dysfunction and reduced CSE expression. Thus, the aim of this post hoc study was to test the hypothesis whether there is an interplay between CSE expression and kidney dysfunction, mitochondrial activity, and oxidative/nitrosative stress in porcine septic AKI with underlying coronary artery disease.Methods: This study is a post hoc analysis of material from anesthetized and instrumented swine with a high fat diet-induced hypercholesterolemia and atherosclerosis undergoing faecal peritonitis-induced septic shock or sham procedure and intensive care (comprising fluid resuscitation and continuous i.v. noradrenaline (NoA) infusion) for 24 h. Glucose metabolism was quantified from blood 13C6-glucose and expiratory 13CO2/12CO2 isotope enrichment during 13C6-glucose infusion. Mitochondrial activity was determined by high- resolution respirometry. CSE and PGC1α expression, as well as nitrotyrosine formation and albumin extravasation, were quantified by immunohistochemistry of formalin-fixed kidney paraffin sections.Results: Sepsis was associated with lactic acidosis (p = 0.004) and AKI (50% fall of creatinine clearance (CrCl), p = 0.019). While both whole-body glucose production (p = 0.004) and oxidation (p = 0.006) were increased, kidney tissue mitochondrial respiration was reduced (p = 0.028), coinciding with decreased CSE (p = 0.003) and PGC1α (p = 0.003) expression. Albumin extravasation (p = 0.011) and nitrotyrosine formation (p = 0.008) were increased in septic kidneys.Conclusions: Sepsis-induced AKI is associated with disturbed mitochondrial respiration and biogenesis, which may be aggravated by oxidative and nitrosative stress. Our results confirm previous data in murine septic shock and porcine hemorrhage and resuscitation on the crucial role of CSE for barrier integrity and kidney functio

Effects of commonly used antiviral vaccines on human plasmacytoid dendritic cells

Human plasmacytoid dendritic cells (pDCs) represent a special subset of immune cells that play an important role in antiviral immunity by stimulating T cell responses and linking the innate and adaptive immune system. Despite their well-recognised antiviral role, little is known about the contribution of pDCs to vaccine-induced immunity. Beside their immunogenic functions, pDCs are also capable to suppress T cell proliferation e.g. by secretion of granzyme B (GrB). However, the regulation of pDC-derived GrB has rarely been investigated so far. This study analysed the effects of commonly used antiviral vaccines against polio, measles, yellow fever, rubella and tick-borne encephalitis on pDCs with a special focus on GrB. Expression and secretion of GrB by pDCs decreased upon stimulation with all tested vaccines. Furthermore, tick-borne encephalitis vaccine (TBEV) as one of the strongest suppressors of GrB inhibited transfer of GrB to T cells. In contrast to the general influence of the vaccines on pDC-derived GrB, only TBEV induced substantial secretion of interferon-alpha (IFN-alpha) and the expression of the costimulatory surface molecule cluster of differentiation (CD)86. Despite the immunostimulatory effects of the vaccines, the potential of pDCs to stimulate T cell proliferation was only weakly modulated. The immunogenic influence of the vaccines on pDCs demonstrated in the present study argues for a direct contribution of pDCs to vaccine-induced immune responses. Hence, these vaccines might be used as clinically available, activating agents for pDCs and other dendritic cells in the context of immunotherapeutic approaches, e.g. anticancer vaccines. The inhibitory effect of the vaccines on immunosuppressive pDC-derived GrB suggests a novel mechanism of how commonly used antiviral vaccines influence the immune system and suggests the evaluation of novel GrB inhibitors as vaccine adjuvants

Automated mechanical cardiopulmonary resuscitation devices versus manual chest compressions in the treatment of cardiac arrest: protocol of a systematic review and meta-analysis comparing machine to human

Introduction Cardiac arrest is a leading cause of death in industrialised countries. Cardiopulmonary resuscitation (CPR) guidelines follow the principles of closed chest compression as described for the first time in 1960. Mechanical CPR devices are designed to improve chest compression quality, thus considering the improvement of resuscitation outcomes. This protocol outlines a systematic review and meta-analysis methodology to assess trials investigating the therapeutic effect of automated mechanical CPR devices at the rate of return of spontaneous circulation, neurological state and secondary endpoints (including short-term and long-term survival, injuries and surrogate parameters for CPR quality) in comparison with manual chest compressions in adults with cardiac arrest.Methods and analysis A sensitive search strategy will be employed in established bibliographic databases from inception until the date of search, followed by forward and backward reference searching. We will include randomised and quasi-randomised trials in qualitative analysis thus comparing mechanical to manual CPR. Studies reporting survival outcomes will be included in quantitative analysis. Two reviewers will assess independently publications using a predefined data collection form. Standardised tools will be used for data extraction, risks of bias and quality of evidence. If enough studies are identified for meta-analysis, the measures of association will be calculated by dint of bivariate random-effects models. Statistical heterogeneity will be evaluated by I2-statistics and explored through sensitivity analysis. By comprehensive subgroup analysis we intend to identify subpopulations who may benefit from mechanical or manual CPR techniques. The reporting follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.Ethics and dissemination No ethical approval will be needed because data from previous studies will be retrieved and analysed. Most resuscitation studies are conducted under an emergency exception for informed consent. This publication contains data deriving from a dissertation project. We will disseminate the results through publication in a peer-reviewed journal and at scientific conferences.PROSPERO registration number CRD42017051633

Complement C5a Alters the Membrane Potential of Neutrophils during Hemorrhagic Shock

Background. Polymorphonuclear granulocytes (PMN) play a crucial role in host defense. Physiologically, exposure of PMN to the complement activation product C5a results in a protective response against pathogens, whereas in the case of systemic inflammation, excessive C5a substantially impairs neutrophil functions. To further elucidate the inability of PMN to properly respond to C5a, this study investigates the role of the cellular membrane potential of PMN in response to C5a. Methods. Electrophysiological changes in cellular and mitochondrial membrane potential and intracellular pH of PMN from human healthy volunteers were determined by flow cytometry after exposure to C5a. Furthermore, PMN from male Bretoncelles-Meishan-Willebrand cross-bred pigs before and three hours after severe hemorrhagic shock were analyzed for their electrophysiological response. Results. PMN showed a significant dose- and time-dependent depolarization in response to C5a with a strong response after one minute. The chemotactic peptide fMLP also evoked a significant shift in the membrane potential of PMN. Acidification of the cellular microenvironment significantly enhanced depolarization of PMN. In a clinically relevant model of porcine hemorrhagic shock, the C5a-induced changes in membrane potential of PMN were markedly diminished compared to healthy littermates. Overall, these membrane potential changes may contribute to PMN dysfunction in an inflammatory environment