Potential role of poly(adenosine 5'-diphosphate-ribose) polymerase activation in the pathogenesis of myocardial contractile dysfunction associated with human septic shock

OBJECTIVE: Sepsis is associated with increased production of superoxide and nitric oxide, with consequent peroxynitrite generation. Cardiodepression is induced in the heart during oxidative stress associated with septic shock. Oxidative and nitrosative stress can lead to activation of the nuclear enzyme poly(adenosine 5'-diphosphate [ADP]-ribose) polymerase (PARP), with subsequent loss of myocardial contractile function. The aim of the study was to investigate whether cardiodepression found in septic patients is associated with plasma markers of myocardial necrosis and with myocardial PARP activation. DESIGN: Prospective and observational study. SETTING: University hospital intensive care unit for clinical and surgical patients. PATIENTS: Twenty-five patients older than 18 yrs presenting with severe sepsis or septic shock. Patients with history of chronic heart failure, cancer, coronary artery disease, diabetes, or acquired immune deficiency syndrome were excluded. INTERVENTIONS: Patients were followed for 28 days, and biochemical and hemodynamic data were collected on days 1, 3, and 6 of sepsis. The groups were survivors and nonsurvivors, defined only after the end of clinical patient evolution. Heart sections from patients who died were analyzed with hematoxylin-eosin and Picro Sirius-Red immunostaining and with electron microscopy. MEASUREMENTS AND MAIN RESULTS: The study population included 25 individuals, of whom 12 (48%) died during the 6 days of follow-up. The initial data of the inflammation marker C-reactive protein and Acute Physiologic and Chronic Health.Evaluation severity were similar in both groups (nonsurvivors, 26 +/- 2; survivors, 24 +/- 5; NS). Overall, an increase in plasma troponin level was related to increased mortality risk. In patients who died, significant myocardial damage was detected, and histologic analysis of heart sections showed inflammatory infiltration, increased collagen deposition, and derangement of mitochondrial cristae. Immunohistochemical staining for poly(ADP-ribose) (PAR), the product of activated PARP, was demonstrated in septic hearts. There was a positive correlation between PAR staining densitometry and troponin I (r(2) = 0.73; p < .05), and the correlation of PAR staining densitometry and left ventricular systolic stroke work index was r(2) = 0.33 (p = .0509). CONCLUSION: There is significant PARP activation in the hearts of septic patients with impaired cardiac function. We hypothesize that PARP activation may be partly responsible for the cardiac depression seen in humans with severe sepsis.     

An unexpected role for the anaphylatoxin C5a receptor in allergic sensitization

The anaphylatoxins complement component 3a and 5a (C3a and C5a, respectively) are classically seen as proinflammatory mediators of allergic asthma that recruit inflammatory cells, induce edema, and cause bronchoconstriction. A few years ago, controversy arose when it was shown that C5-deficient mice were more susceptible to experimental asthma compared with C5-sufficient mice. In a study by K?hl et al. in this issue of the JCI, it is shown in a series of truly "complementary" experiments that C5a receptor (C5aR) blockade promotes Th2 sensitization upon first exposure to inhaled allergen, whereas C5aR blockade during established inflammation suppresses the cardinal features of asthma (see the related article beginning on page 783). Blockade of C5aR alters the function of airway DCs, crucial for inducing and maintaining Th2 responses in the lung. Targeting C5aR as a treatment for established asthma could be beneficial, but might be accompanied by sensitization to novel antigens.     

Inhibition of complement C5a prevents breakdown of the blood-brain barrier and pituitary dysfunction in experimental sepsis

Introduction

Septic encephalopathy secondary to a breakdown of the blood-brain barrier (BBB) is a known complication of sepsis. However, its pathophysiology remains unclear. The present study investigated the effect of complement C5a blockade in preventing BBB damage and pituitary dysfunction during experimental sepsis.

Methods

Using the standardised caecal ligation and puncture (CLP) model, Sprague-Dawley rats were treated with either neutralising anti-C5a antibody or pre-immune immunoglobulin (Ig) G as a placebo. Sham-operated animals served as internal controls.

Results

Placebo-treated septic rats showed severe BBB dysfunction within 24 hours, accompanied by a significant upregulation of pituitary C5a receptor and pro-inflammatory cytokine expression, although gene levels of growth hormone were significantly attenuated. The pathophysiological changes in placebo-treated septic rats were restored by administration of neutralising anti-C5a antibody to the normal levels of BBB and pituitary function seen in the sham-operated group.

Conclusions

Collectively, the neutralisation of C5a greatly ameliorated pathophysiological changes associated with septic encephalopathy, implying a further rationale for the concept of pharmacological C5a inhibition in sepsis.     

The role of CXCL10 in the pathogenesis of experimental septic shock

Introduction

The chemokine CXCL10 is produced during infection and inflammation to activate the chemokine receptor CXCR3, an important regulator of lymphocyte trafficking and activation. The goal of this study was to assess the contributions of CXCL10 to the pathogenesis of experimental septic shock in mice.

Methods

Septic shock was induced by cecal ligation and puncture (CLP) in mice resuscitated with lactated Ringer’s solution and, in some cases, the broad spectrum antibiotic Primaxin. Studies were performed in CXCL10 knockout mice and mice treated with anti-CXCL10 immunoglobulin G (IgG). Endpoints included leukocyte trafficking and activation, core body temperature, plasma cytokine concentrations, bacterial clearance and survival.

Results

CXCL10 was present at high concentrations in plasma and peritoneal cavity during CLP-induced septic shock. Survival was significantly improved in CXCL10 knockout (CXCL10KO) mice and mice treated with anti-CXCL10 IgG compared to controls. CXCL10KO mice and mice treated with anti-CXCL10 IgG showed attenuated hypothermia, lower concentrations of interleukin-6 (IL-6) and macrophage inhibitory protein-2 (MIP-2) in plasma and lessened natural killer (NK) cell activation compared to control mice. Compared to control mice, bacterial burden in blood and lungs was lower in CXCL10-deficient mice but not in mice treated with anti-CXCL10 IgG. Treatment of mice with anti-CXCL10 IgG plus fluids and Primaxin at 2 or 6 hours after CLP significantly improved survival compared to mice treated with non-specific IgG under the same conditions.

Conclusions

CXCL10 plays a role in the pathogenesis of CLP-induced septic shock and could serve as a therapeutic target during the acute phase of septic shock.     

脓毒症心功能障碍研究进展

脓毒症在急诊有着高发病率和致死率,临床上发现脓毒症患者发生心功能障碍的程度不同,这可能与不同的免疫状态及基因型相关.目前已证明体内心肌抑制的潜在病理生理学机制,但有心功能障碍的脓毒血症患者的死亡率并没有明显下降.因此,深入研究脓毒血症引起心功能障碍的机制十分重要,本文主要总结目前脓毒症心肌损伤分子机制、临床监测及治疗手段的最新进展,试图对将来临床及基础研究有所启发.     

Nociceptive sensitization by complement C5a and C3a in mouse

Activation of the complement system by injury increases inflammation by producing complement fragments C5a and C3a which are able to recruit and activate immune cells. Complement activation may contribute to pain after inflammation and injury. In this study, we examined whether C5a and C3a elicit nociception when injected into mouse hind paws in vivo, and whether C5a and C3a activate and/or sensitize mechanosensitive nociceptors when applied on peripheral terminals in vitro. We also examined the dorsal root ganglia (DRG) for C5a receptor (C5aR) mRNA and effects of C5a and C3a on intracellular Ca²⁺ concentration ([Ca²⁺]_i) using Ca²⁺ imaging. Heat hyperalgesia was elicited by intraplantar injection of C5a, and mechanical hyperalgesia by C5a and C3a. After exposure to either C5a or C3a, C-nociceptors were sensitized to heat as evidenced by an increased proportion of heat responsive fibers, lowered response threshold to heat and increased action potentials during and after heat stimulation. A-nociceptors were activated by complement. However, no change was observed in mechanical responses of A- and C-nociceptors after C5a and C3a application. The presence of C5aR mRNA was detected in DRG. C5a and C3a application elevated [Ca²⁺]_i and facilitated capsaicin-induced [Ca²⁺]_i responses in DRG neurons. The results suggest a potential role for complement fragments C5a and C3a in nociception by activating and sensitizing cutaneous nociceptors.     

Pexelizumab -- a C5 complement inhibitor for use in both acute myocardial infarction and cardiac surgery with cardiopulmonary bypass

Myocardial injury and dysfunction in acute infarction and during cardiac surgery with cardiopulmonary bypass (CPB) are associated with an undesirable systemic inflammatory response, in which the complement cascade plays a major role. In animal models C5 inhibition has been found to significantly reduce myocardial infarct size and decrease cellular necrosis and apoptosis. Pexelizumab (Alexion Pharmaceuticals, Inc., Cheshire, CT, USA) is a humanized, monoclonal, single-chain antibody fragment that inhibits C5, thereby blocking its cleavage into active forms. Prospective, randomised, double-blind, placebo-controlled trials using pexelizumab during percutaneous coronary intervention following acute myocardial infarction (AMI), or in patients undergoing coronary artery bypass graft (CABG) with CPB, have demonstrated a reduction in morbidity and mortality. Thus, pexelizumab represents a promising therapeutic option with sustained benefit both in AMI and during CABG with CPB.     

Solid-phase radioimmunoassay of human complement fragment C5a

In this competitive RIA for determining concentrations of human C5a in biological fluids and in buffers, labeled C5a and sample are allowed to compete for binding to a limited amount of goat antibody to human C5a in solution. Free and bound tracer are then separated by a second antibody (rabbit anti-goat IgG) immobilized on paramagnetic particles. Total incubation time for this assay is 70 min. Sensitivity, precision, and analytical recovery of this assay compare well with those of a reference method.     

A myocardial cytotoxic process is involved in the cardiac dysfunction of meningococcal septic shock

OBJECTIVE: Myocardial dysfunction is a characteristic component of meningococcal septic shock and contributes to the persisting high mortality from the disease. Specific treatment of the myocardial failure has been hampered by the lack of understanding of its pathophysiology. We were interested to determine whether myocardial cell death was occurring in the presence of meningococcal septicemia and whether it correlated with the degree of left ventricular dysfunction and disease severity. We therefore investigated the release of cardiac troponin I (cTnI), a sensitive and specific marker of myocardial cell death, and related this to the severity of disease and cardiac dysfunction. DESIGN: Prospective study SETTING: Pediatric intensive care unit SUBJECTS: Patients admitted to the pediatric intensive care unit with a diagnosis of meningococcal septicemia. INTERVENTIONS: Serum concentrations of cTnI were determined at admission to intensive care in 101 children with meningococcal septicemia and serially in 37 children. Changes in cTnI were related to disease severity as measured by the Pediatric Risk of Mortality score and two markers of cardiac dysfunction. MEASUREMENTS AND MAIN RESULTS: Serum concentrations of cTnI were elevated above the range for healthy children in 24% of children with meningococcal septicemia at admission and in 62% of patients within 48 hrs. The peak concentrations occurred between 12 and 36 hrs after admission. There were significant correlations between cTnI levels and disease severity and between cTnI levels and the degree of myocardial depression measured by quantitative transthoracic echocardiography and peak inotrope requirements. CONCLUSIONS: The elevated serum concentrations of cTnI indicate that myocardial cell death is occurring in meningococcal septicemia. The relationship between cTnI and markers of myocardial function suggest that the cell death may have a role in the pathogenesis of myocardial dysfunction in meningococcal septicemia. Elucidation of the mechanism responsible for myocardial injury may lead to the development of therapeutic interventions to prevent or limit this cardiac damage.     

白细胞在创伤后心功能不全中的作用

目的　探讨创伤后心肌组织是否存在着白细胞浸润 ,并研究白细胞在心脏功能不全中的作用。方法　麻醉后的雄性小鼠被随机分为创伤组和对照组 (2 5只 /组 ) ,在创伤后 6h测定两组小鼠平均动脉压(MAP)、心脏功能指标和心肌组织髓过氧化物酶 (MPO)活性。结果　创伤组小鼠出现了明显的低血压和心脏功能不全 [创伤组平均动脉压 (MAP)、等容收缩期室内压最大变化速率 (+dp dtmax) ,心脏指数(CI)分别为 (70± 9)mmHg ,(3492± 2 76 )mmHg/s ,(6 2± 6 )ml/min/ 10 0g ;对照组分别为 (90± 8)mmHg ,(474 5± 2 19)mmHg/s,(72± 7)ml/min/ 10 0g ,P <0 0 5 ];创伤组小鼠心肌组织MPO活性明显增高 [创伤组为 (8 4 6± 1 70 )U/ 10 0mg ,对照组为 (4 5 2± 0 94 )U/ 10 0mg,P <0 0 5 ],且MPO活性与心脏功能呈明显负相关。结论　创伤后心肌组织的炎症反应是导致创伤后心功能不全的一个重要因素 ,提示抗炎治疗对于改善创伤后心功能不全具有潜在的治疗价值     

The role of endothelial dysfunction in the pathogenesis of combined cardiopulmonary diseases

The aim of the study was to evaluate the endothelial function in patients with coronary heart disease and an exacerbation of chronic obstructive pulmonary disease (COPD), and the role of endothelial dysfunction (ED) in the pathogenesis of reciprocal exacerbation syndrome in cases of combined cardiovascular pathology. The subjects were 366 patients with single or combined cardiovascular diseases, in whom non-invasive evaluation of the endothelial regulation of the vascular tone was performed, and serum levels of NO were measured. The study revealed the biggest number of cases with an altered endothelium-dependent vasodilatation, and the most prominent decrease in NO level in patients with CHD and COPD. All the patients were followed up during two years in order to compare clinical manifestations of single and combined cardiovascular pathology. The results show that ED may be considered a predictor of complicated clinical course of COPD in patients with CHD.     

The proinflammatory mediators C3a and C5a are essential for liver regeneration

Complement has been implicated in liver repair after toxic injury. Here, we demonstrate that complement components are essential for liver regeneration, and mediate their effect by interacting with key signaling networks that promote hepatocyte proliferation. C3- or C5-deficient mice exhibited high mortality, parenchymal damage, and impaired liver regeneration after partial hepatectomy. Mice with dual C3 and C5 deficiency had a more exacerbated phenotype that was reversed by combined C3a and C5a reconstitution. Interception of C5a receptor signaling resulted in suppression of IL-6/TNFalpha induction and lack of C3 and C5a receptor stimulation attenuated nuclear factor-kappaB/STAT-3 activation after hepatectomy. These data indicate that C3a and C5a, two potent inflammatory mediators of the innate immune response, contribute essentially to the early priming stages of hepatocyte regeneration.     

Evaluation of complement system proteins C3a,C5a and C6 in patients of endometriosis

BackgroundEndometriosis is a disease that shows auto-immune and chronic characteristics, suggesting a role for proteins mediating immune interactions in its pathophysiology. The aim was to evaluate C3a and C5a for their role in inflammatory responses and C6 as the down-stream interactor following our previous findings on C5 mRNA expression changes in endometriosis [1].MethodsSera from 71 endometriosis patients and 77 women without endometriosis were taken. While the samples were taken only once from the controls, the patient samples were taken before, in 1st and in 7th days after laparoscopy. Levels of complement proteins C3a, C5a and C6 were measured with ELISA assays. MPV (Mean Platelet Volume), CRP (C-Reactive Protein) and NLR (Neutrophil-to-Leukocyte Ratio) were also analyzed from the retrospective data.ResultsC6 levels of early-stage patients at postoperative 1st day were significantly higher than controls. Patients with high MPV measurements had significantly higher C3a (p < 0.0001) and C6 (p < 0.05) levels than controls at all times of measurement.ConclusionsC6, an integral component of the membrane attack complex (MAC), could play a role at early disease-stage. The changes in levels of complement proteins and their relation to high MPV levels suggest a broader area of interplay for immune interactors in endometriosis. Although a bigger and longitudinal study design is needed to obtain more accurate results to evaluate these proteins as potential biomarkers, an important role of complement system within the pathophysiology of endometriosis is apparent.     

The role of gut mucosal hypoperfusion in the pathogenesis of post-operative organ dysfunction

Conclusion In the quest for an absolute monitor of tissue oxygen utilisation the tonometer is, unfortunately, not the Holy Grail. However, the tonometer is commercially available and a practical monitor of gut mucosal perfusion for use in the peri-operative period. As the tonometer is not yet in general use we are faced with an ideal opportunity to audit its introduction, something we have failed to do for other clinical monitors.     

Left ventricular systolic dysfunction during septic shock: the role of loading conditions

Purpose

The clinical significance of septic myocardial dysfunction is controversial, a fact that may be explained by the influence of loading conditions. Many indices may be useful to characterize cardiac function during septic shock, but their feasibility and physiological coherence in the clinical setting are unknown.

Methods

Hemodynamic and echocardiographic data with tissue Doppler and speckle tracking were prospectively recorded on the first 3 days of human septic shock. Hypokinesia, normokinesia, and hyperkinesia were defined as a left ventricular ejection fraction (LVEF) of <45, 45–60, and >60%, respectively. Twelve hemodynamic indices exploring contractility and loading conditions were assessed and analyzed.

Results

Two hundred and ninety-seven echocardiographies were performed in 132 patients. During the first 24 h (H_1–24), 48 (36.4%) patients were hyperkinetic, 55 (41.7%) were normokinetic, and 29 (22.0%) patients were hypokinetic. Thirteen patients had a secondary hypokinesia absent at H_1–24 but present at H_25–48 or H_49–72, for an overall incidence of 42 (31.8%) during the first 3 days. Despite a limited feasibility (<50%), global LV longitudinal peak systolic strain was impaired in a majority (>70%) of the patients assessed, including all those with depressed LVEF, and declined early in patients whose LVEF secondarily deteriorated. Most contractility indices were inversely correlated with afterload indices. Hyperkinetic patients exhibited the worst reduction in afterload indices. Hospital mortality was significantly higher in patients with LV hyperkinesia than in their counterparts: 30 (62.5%) vs. 35 (41.7%), p = 0.02.

Conclusions

Speckle tracking-derived strain was reduced in the majority of patients with septic shock, revealing covert septic myocardial dysfunction, but had poor feasibility. We found an inverse correlation between most of the contractility and afterload indices. Precise evaluation of afterload is crucial for adequate interpretation of LV systolic function in this setting.

     

全心舒张末期容积指数对心功能不全并脓毒性休克患者液体复苏的应用价值

目的探讨全心舒张末期容积指数（GEDI）指导心功能不全并脓毒性休克患者液体复苏的临床价值。 方法选择2016年1月至2018年1月收住杭州师范大学附属医院重症医学科的心功能不全并脓毒性休克患者共41例,分为中心静脉压组（CVP组）和GEDI组,其中CVP组21例,GEDI组20例。CVP组按照脓毒症指南进行常规早期目标导向治疗;GEDI组进行脉搏指示连续心输出量监测,根据GEDI指导液体复苏,使GEDI达到680 ~ 800 mL / m²,余复苏目标（平均动脉压、中心静脉血氧饱和度、尿量）同常规EGDT方案。观察两组患者达到复苏目标所需液体总量、24 h血管外肺水指数（EVLWI）、6 h及24 h脑尿钠肽、乳酸清除率、去甲肾上腺素用量。 结果GEDI组达到复苏目标时所需液体总量少于CVP组[（2 572 ± 1 108）mL vs.（3 327 ± 925）mL,t = 2.375,P = 0.023）]。GEDI组24 h EVLWI[7.3（5.5,8.8）mL / kg vs. 9.6（8.9,9.8）mL / kg]、6 h脑尿钠肽[889.0（340.3,1 270.0）ng / L vs. 1 746.0（634.0,2 160.0）ng / L]与24 h脑尿钠肽[684.5（192.5,749.9）ng / L vs. 1 120.0（400.5,2 480.0）ng / L]均低于CVP组（Z = 86.500、120.000、124.000,P = 0.001、0.020、0.026）。GEDI组6 h乳酸清除率[34.21（15.64,45.87）% vs. 20.00（0.00,33.19）%,Z = 129.5,P = 0.037]优于CVP组,且能减少去甲肾上腺素用量[（0.9 ± 0.6）mg / kg vs. （1.9 ± 1.5）mg / kg,t’ = 2.817,P = 0.009]。 结论心功能不全患者合并脓毒性休克时以GEDI指导的液体复苏能达到更有效的早期液体复苏目标,所需复苏液体总量及血管活性药物相对较少,肺水增加较轻且不明显加重心功能损害。     

In vivo clearance and tissue distribution of C5a and C5a des arginine complement fragments in rabbits.

We have previously shown a marked difference in the inflammatory response to human C5a or C5a des arginine (Arg) instilled in rabbit lungs. These studies raised the question of where C5a and C5a des Arg are processes in vivo and what role neutrophils may play in the tissue distribution of these two mediators. After intravenous injection of purified, biologically active 125I-C5a or 125I-C5a des Arg, adult rabbits were serially bled and then killed at various time intervals. Although greater than 50% of the injected radioactivity was cleared from the circulation within 2 min for both mediators, C5a des Arg persisted in the circulation longer than C5a. C5a instillation caused an acute neutropenia, whereas C5a des Arg caused a less severe and more prolonged neutropenia, preceding a neutrophilic response observed with both mediators. Clearance of the mediators was primarily seen in the highly vascularized organs: the lung, spleen, liver, and kidney. A time-dependent accumulation was seen initially in the lung, followed by the spleen, liver, and kidney. Histologic examination showed a marked increase in the number of neutrophils within the lung and spleen. Depletion of circulating neutrophils by nitrogen mustard pretreatment of rabbits showed no change in the amount of labeled mediator bound in the lung, whereas splenic accumulation was dependent on the presence of neutrophils. These results indicate that C5a and C5a des Arg are rapidly removed from the circulation by specific accumulation in vascularized tissues. Clearance by the lung was not affected by neutrophil depletion, whereas clearance by the spleen was dependent on neutrophils. These experiments further suggest there are neutrophil-dependent and neutrophil-independent mechanisms involved in the removal of C5a and C5a des Arg from the circulation and that binding of C5 fragments in the pulmonary vasculature may precede and then induce neutrophil sequestration.