Endothelial oxidative stress induced by serum from patients with severe trauma hemorrhage

Oxidative Stress and Neonatal Respiratory Extracorporeal Membrane Oxygenation

Oxidative stress is a frequent condition in critically ill patients, especially if exposed to extracorporeal circulation, and it is associated with worse outcomes and increased mortality. The inflammation triggered by the contact of blood with a non-endogenous surface, the use of high volumes of packed red blood cells and platelets transfusion, the risk of hyperoxia and the impairment of antioxidation systems contribute to the increase of reactive oxygen species and the imbalance of the redox system. This is responsible for the increased production of superoxide anion, hydrogen peroxide, hydroxyl radicals, and peroxynitrite resulting in increased lipid peroxidation, protein oxidation, and DNA damage. The understanding of the pathophysiologic mechanisms leading to redox imbalance would pave the way for the future development of preventive approaches. This review provides an overview of the clinical impact of the oxidative stress during neonatal extracorporeal support and concludes with a brief perspective on the current antioxidant strategies, with the aim to focus on the potential oxidative stress-mediated cell damage that has been implicated in both short and long-term outcomes.

Post-translational oxidative modification of fibrinogen is associated with coagulopathy after traumatic injury

Victims of trauma often develop impaired blood clot formation (coagulopathy) that contributes to bleeding and mortality. Fibrin polymerization is one critical component of clot formation that can be impacted by post-translational oxidative modifications of fibrinogen after exposure to oxidants. In vitro evidence suggests that Aα-C domain methionine sulfoxide formation, in particular, can induce conformational changes that prevent lateral aggregation of fibrin protofibrils during polymerization. We used mass spectrometry of plasma from trauma patients to find that fibrinogen Aα-C domain methionine sulfoxide content was selectively-increased in patients with coagulopathy vs. those without coagulopathy. This evidence supports a novel linkage between oxidative stress, coagulopathy, and bleeding after injury.

Therapeutic Effects of Intravenous Infusion of Hyperoxygenated Solution on Acute Haemorrhagic Shock in Rabbits

Tissue anoxia is the main mechanism of the shock reaction. Here, the effect of hyperoxygenated solution (HOS) on acute haemorrhagic shock was studied in rabbits. At 60 min after shock, rabbits were infused intravenously with hyperoxygenated solution at 10 (HOS1 group) or 20 ml/kg (HOS2 group) or with Ringer's solution at 10 ml/kg (RS group). Compared with values before shock, values after shock were lower for mean arterial pressure (MAP), more negative for base excess (BE) and higher for blood lactate (BL) and blood viscosity. After infusion, MAP declined more slowly in the HOS1 and HOS2 groups than in the RS group. At 30 and 60 min after infusion, arterial partial pressure of oxygen (PaO2) and oxygen saturation (SaO2) were higher and BE was less negative in the HOS1 and HOS2 groups than in the RS group, BL was lower in the HOS1 and HOS2 groups than in the RS group, and PaO2 and SaO2 were higher in the HOS2 group than in the HOS1 group. It was concluded that HOS infusion can rectify changes in vital signs more effectively than Ringer's solution after acute haemorrhagic shock in rabbits.

Postresuscitation syndrome: potential role of hydroxyl radical-induced endothelial cell damage

OBJECTIVE

After out of hospital cardiac arrest, it has been reported that endothelium dysfunction may occur during the postresuscitation syndrome. However, the consequences of the reperfusion phase on endothelial reactive oxygen species production and redox homeostasis have not been explored in out of hospital cardiac arrest patients.

DESIGN

Prospective, observational study.

SETTING

Medical intensive care unit in a university hospital.

PATIENTS

Twenty successfully resuscitated out of hospital cardiac arrest patients, seven septic shock patients, and ten healthy volunteers.

INTERVENTION

Plasma was collected from patients at admission and 12, 24, 36, 48, and 72 hrs after cardiac arrest. We studied the production of reactive oxygen species and cell survival during plasma perfusion using perfused endothelial cells (human umbilical vein endothelial cells) as a model. Cell antioxidant response was studied by measuring superoxide dismutase, glutathione peroxidase, and glutathione reductase activities and reduced and oxidized glutathione levels. Mitochondrial respiratory chain activity was assessed by measuring complex I, II, III, and IV activities and anaerobic glycolysis by measuring glucose-6-phosphate dehydrogenase activity.

MEASUREMENTS AND MAIN RESULTS

Using perfused endothelial cells as a model, we demonstrate that plasma from out of hospital cardiac arrest patients induced on naive human umbilical vein endothelial cells a significant and massive cell death compared to plasma from septic shock patients and healthy volunteers. An increase of reactive oxygen species production with a decrease in antioxidant defenses (superoxide dismutase, glutathione peroxidase, and glutathione reductase activities, reduced and oxidized glutathione levels) was observed. The metabolic consequence of plasma exposure showed that mitochondrial respiratory chain activity was significantly impaired and anaerobic glycolysis was significantly increased. Inhibiting hydroxyl radical production significantly decreased cell death, suggesting that plasma from out of hospital cardiac arrest induced significant cell death by triggering the Fenton reaction.

CONCLUSION

Plasma from out of hospital cardiac arrest induces major endothelial toxicity with an acute pro-oxidant state in the cells and impairment of mitochondrial respiratory chain activity. This toxicity could be due to hydroxyl radical production by activation of the Fenton reaction.

Medical pre-hospital management reduces mortality in severe blunt trauma: a prospective epidemiological study

INTRODUCTION

Severe blunt trauma is a leading cause of premature death and handicap. However, the benefit for the patient of pre-hospital management by emergency physicians remains controversial because it may delay admission to hospital. This study aimed to compare the impact of medical pre-hospital management performed by SMUR (Service Mobile d'Urgences et de Réanimation) with non-medical pre-hospital management provided by fire brigades (non-SMUR) on 30-day mortality.

METHODS

The FIRST (French Intensive care Recorded in Severe Trauma) study is a multicenter cohort study on consecutive patients with severe blunt trauma requiring admission to university hospital intensive care units within the first 72 hours. Initial clinical status, pre-hospital life-sustaining treatments and Injury Severity Scores (ISS) were recorded. The main endpoint was 30-day mortality.

RESULTS

Among 2,703 patients, 2,513 received medical pre-hospital management from SMUR, and 190 received basic pre-hospital management provided by fire brigades. SMUR patients presented a poorer initial clinical status and higher ISS and were admitted to hospital after a longer delay than non-SMUR patients. The crude 30-day mortality rate was comparable for SMUR and non-SMUR patients (17% and 15% respectively; P = 0.61). After adjustment for initial clinical status and ISS, SMUR care significantly reduced the risk of 30-day mortality (odds ratio (OR): 0.55, 95% CI: 0.32 to 0.94, P = 0.03). Further adjustments for the delay to hospital admission only marginally affected these results.

CONCLUSIONS

This study suggests that SMUR management is associated with a significant reduction in 30-day mortality. The role of careful medical assessment and intensive pre-hospital life-sustaining treatments needs to be assessed in further studies.

Rons formation under restrictive reperfusion does not affect organ dysfunction early after hemorrhage and trauma

Reactive oxygen species have been implicated in the pathophysiology of early reperfusion. We aimed to determine 1) reactive oxygen and nitrogen species (RONS) formation in organs of rats and 2) its pathophysiological relevance during a phase of restrictive reperfusion after hemorrhagic/traumatic shock (HTS). Fifty-seven male Sprague-Dawley rats were subjected to a clinically relevant HTS model, featuring laparotomy, bleeding, and a phase of restrictive reperfusion. The RONS scavenger 1-hydroxy-3-carboxy-2,2,5,5-tetramethyl-pyrrolidine hydrochloride (continuous i.v. infusion) and electron paramagnetic resonance spectroscopy were applied for RONS (primarily superoxide and peroxynitrite) detection. Compared with sham-operated animals, the organ-specific distribution of RONS changed during restrictive reperfusion after HTS. Reactive oxygen and nitrogen species formation increased during restrictive reperfusion in red blood cells and ileum only but decreased in the kidney and remained unchanged in other organs. Hemorrhagic traumatic shock followed by restrictive reperfusion resulted in metabolic acidosis, dysfunction of liver and kidney, and increased oxidative burst capacity in circulating cells. Plasma RONS correlated with shock severity and organ dysfunction. However, RONS scavenging neither affected organ dysfunction nor oxidative burst capacity nor myeloperoxidase activity in lung when compared with the shock controls. In summary, a phase of restrictive reperfusion does not increase RONS formation in most organs except in intestine and red blood cells. Moreover, scavenging of RONS does not affect the early organ dysfunction manifested at the end of a phase of restrictive reperfusion.

Oxidant alterations in CD16 expression are cytoskeletal induced

Oxidative stress during reperfusion of ischemia is associated with a phenotypic change in circulating monocytes from CD14++CD16- to a proinflammatory CD14+CD16+ subpopulation resulting in altered immunity and development of organ failure. However, the mechanism responsible remains unknown. We hypothesize that this phenotypic change, modeled by hydrogen peroxide exposure in vitro, is due to oxidative-induced intracellular calcium flux and distinct cytoskeletal and lipid raft changes. Peripheral blood monocytes obtained from healthy volunteers underwent 100 mM H2O2 exposure for 0 to 24 h. Selected cells were pretreated with 2 microM cytochalasin D, 1 microM lactrunculin A, or 30 microM 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid for 30 min. Cells underwent fluorescence-activated cell sorter for CD14, CD16, and cytokine expression. Cellular and lipid raft CD16 expression was determined by immunoblot and confocal microscopy. H2O2 exposed monocytes underwent a rapid time-dependent increase in the surface expression of CD16 from 12.81% +/- 3.53% to 37.12% +/- 7.61% at 24 h (P = 0.001). Total cellular CD16 was not changed by H2O2, but an increase in lipid raft and decrease in intracellular CD16 expression were seen after H2O2 exposure. This increase in CD16 expression was associated with a 27% increase in intracellular TNF-alpha, an alteration in actin polymerization, and the formation of raft macrodomains. These changes induced by H2O2 were inhibited by inhibition of actin polymerization (cytochalasin D and lactrunculin A) and intracellular calcium flux [1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid]. This study provides the first evidence that phenotypic alterations induced by oxidative stress during reperfusion may occur as a result of changes in cytoskeletal architecture due to calcium flux that result in lipid raft alterations rather than solely from demargination and/or production of bone marrow-derived CD16+ monocytes.

Plasma-induced endothelial oxidative stress is related to the severity of septic shock*

OBJECTIVE

To estimate the capacity of plasma from septic shock patients to induce in vitro reactive oxygen species (ROS) production by endothelial cells and to analyze whether ROS production is related to the severity of the septic shock.

DESIGN

Prospective, observational study.

SETTING

Medical intensive care unit in a university hospital.

PATIENTS

Twenty-one patients with septic shock.

INTERVENTIONS

The in vitro capacity of plasma from septic shock patients to induce ROS production by naive human umbilical vein endothelial cells (HUVEC) was quantified by using a fluorescent probe (2',7'-dichlorodihydrofluorescein diacetate).

MEASUREMENTS AND MAIN RESULTS

Blood samples were collected on day 1, day 3, and day 5 from 21 consecutive septic shock adult patients and from ten healthy volunteers. Patients mean age was 58 yrs old, mean Sequential Organ Failure Assessment (SOFA) score at admission was 12, mean severity illness assessed by Simplified Acute Physiology Score (SAPS) II was 53, and the mortality rate was 47%. In addition to assessment of in vitro ROS generation by HUVEC, oxidative stress in blood was evaluated by measuring lipid peroxidation products and enzymatic and nonenzymatic antioxidants. Septic shock was associated with oxidative stress and an imbalance in antioxidant status. As compared with controls, plasma-induced ROS production by naive HUVEC was significantly higher in septic shock. Moreover ROS production was significantly correlated with SAPS II (p = .028) and SOFA values (p = .0012) and was higher in nonsurvivors than in survivors. In contrast, no correlation was found between the severity of the septic shock and any of the levels of lipid peroxidation products or enzymatic and nonenzymatic antioxidants.

CONCLUSION

Plasma from septic shock patients induces ROS formation by naive HUVEC, and the extent of ROS formation correlates with mortality and with criteria of the severity of septic shock as SOFA score and SAPS II.

N-acetylcysteine attenuates TNF-alpha-induced human vascular endothelial cell apoptosis and restores eNOS expression

The circulatory inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) is increased in pathological conditions, such as diabetes, which initiate or exacerbate vascular endothelial injury. Both nitric oxide (NO) and reactive oxygen species may play a dual role (i.e., inhibiting or promoting) in TNF-alpha-induced endothelial cell apoptosis. We investigated the effects of the antioxidant N-acetylcysteine on TNF-alpha-induced apoptosis in human vascular endothelial cell (cell line ECV304) apoptosis, NO production and lipid peroxidation. Cultured vascular endothelial cell (ECV304) were either not treated (control), or treated with TNF-alpha (40 ng/ml) alone or TNF-alpha in the presence of N-acetylcysteine at 30 mmol/l or 1 mmol/l, respectively, for 24 h. Cell viability was measured by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. Cell apoptosis was assessed by flow cytometry. TNF-alpha-induced endothelial cell apoptosis was associated with increased inducible NO synthase but reduced endothelial NO synthase (eNOS) protein expression. NO production and the levels of the lipid peroxidation product malondialdehyde were concomitantly increased. Treatment with NAC at 30 mmol/l restored eNOS expression and further increased NO production as compared to TNF-alpha alone, resulting in improved cell viability and reduced apoptosis. This was accompanied by increased superoxide dismutase activity, increased glutathione peroxidase production and reduced malondialdehyde levels. N-acetylcysteine at 1 mmol/l, however, did not have significant effects on TNF-alpha-induced endothelial cell apoptosis and cell viability despite it slightly enhanced glutathione peroxidase production. N-acetylcysteine attenuation of TNF-alpha-induced human vascular endothelial cell apoptosis is associated with the restoration of eNOS expression.

Protective effects of PARP inhibition on liver microcirculation and function after haemorrhagic shock and resuscitation in male rats

OBJECTIVE

The aim of this study was to investigate the impact of the water-soluble poly-(ADP)-ribose-polymerase (PARP) inhibitor 5-aminoisoquinolinone (5-AIQ) on liver microcirculation and function after haemorrhagic shock and resuscitation.

DESIGN

Controlled, randomized animal study.

SETTING

University animal care facility and research laboratory.

SUBJECT

Male Sprague-Dawley rats were subjected to haemorrhagic shock for 1 h, followed by resuscitation with shed blood and crystalloid solution for a total of 5 h.

INTERVENTIONS

The PARP inhibitor 5-AIQ (3 mg/kg; n=7) or vehicle (n=7) was administered 5 min prior to resuscitation. Sham-operated animals without induction of shock served as controls (n=7).

MEASUREMENTS AND RESULTS

Using intravital fluorescence microscopy hepatic microcirculation was assessed at baseline, end of shock phase as well as 1 h and 5 h after resuscitation. Systemic arterial blood pressure and bile flow were continuously monitored. 5-AIQ treatment attenuated shock/resuscitation-induced increase of intrahepatic leukocyte-endothelial cell interaction with a marked reduction of both sinusoidal leukostasis and venular leukocyte adherence. Moreover, nutritive perfusion was found improved, guaranteeing sufficient oxygen supply to tissue, as indicated by low NADH autofluorescence, which was not different to that in controls. Most notably, excretory liver function reached baseline level over 5 h of reperfusion in 5-AIQ-treated animals.

CONCLUSIONS

In the present setting of shock/resuscitation in male rats the PARP inhibitor 5-AIQ proved to be very effective in ameliorating compromised liver microcirculation and function. Further research has to confirm that PARP inhibition is a suitable tool in the acute treatment of patients suffering from reduced circulating blood volume and thus microcirculatory organ dysfunction.

Post-injury treatment with a new antioxidant compound H-290/51 attenuates spinal cord trauma-induced c-fos expression, motor dysfunction, edema formation, and cell injury in the rat

The neuroprotective efficacy of post-injury treatment with the antioxidant compound H-290/51 (10, 30, and 60 minutes after trauma) on immediate early gene expression (c-fos), blood-spinal cord barrier (BSCB) permeability, edema formation, and motor dysfunction was examined in a rat model of spinal cord injury (SCI). SCI was produced by a longitudinal incision into the right dorsal horn of the T10-11 segment under Equithesin anesthesia. Focal SCI in control rats resulted in profound up-regulation of c-fos expression, BSCB dysfunction, edema formation, and cell damage in the adjacent T9 and T12 segments at 5 hours. Pronounced motor dysfunction was present at this time as assessed using the Tarlov scale and the inclined plane test. Treatment with H-290/51 (50 mg/kg, p.o.) 10 and 30 minutes after SCI (but not after 60 minutes) markedly attenuated c-fos expression and motor dysfunction. In these groups, BSCB permeability, edema formation, and cell injuries were mildly but significantly reduced. These observations suggest that (i) antioxidants are capable of attenuating cellular and molecular events following trauma, and (ii) have the capacity to induce neuroprotection and improve motor function if administered during the early phase of SCI, a novel finding.