Pulmonary Ischemia-reperfusion Research Articles

Human α1-antitrypsin improves early post-transplant lung function: Pre-clinical studies in a pig lung transplant model

The translation of novel drugs in lung transplantation is challenged by different physiologic conditions between small animals and humans. Large-animal models provide important pre-clinical evidence and the next step that best informs clinical trials. In the present study, we used a pig lung transplant model to determine whether human α1-antitrypsin (A1AT), a medication shown to prevent pulmonary ischemia-reperfusion injury in rats, could attenuate reperfusion injury after prolonged hypothermic preservation in a large-animal lung transplant model. Donor lungs were preserved for 24 hours at 4°C, followed by lung transplantation. In a randomized and blinded fashion, intravenous A1AT (240 mg/kg; n = 5) or human albumin (n = 5) was administered to the recipient before reperfusion. Allograft gas exchange function and lung mechanics were monitored during a 4-hour reperfusion period. Microscopic lung injury, inflammatory response, coagulation activity, and cell death were assessed. Pulmonary gas exchange was significantly better during the 4-hour reperfusion period in the A1AT group. Treatment with A1AT improved static pulmonary compliance and significantly reduced pulmonary edema and lung permeability. A1AT treatment inhibited inflammatory mediators in the circulation, with reduced activation of nuclear factor-κB and inflammasome, reduced formation of thrombin-antithrombin complex in plasma, and reduced apoptosis in the allografts. Administration of human A1AT before reperfusion in recipients improved immediate post-transplant lung function in pigs. A large-animal survival model should be considered to support further advancement toward a clinical trial of A1AT to prevent primary graft dysfunction in lung transplantation.

Effects of sevoflurane on tight junction protein expression and PKC-α translocation after pulmonary ischemia-reperfusion injury.

Pulmonary dysfunction caused by ischemia-reperfusion injury is the leading cause of mortality in lung transplantation. We aimed to investigate the effects of sevoflurane pretreatment on lung permeability, tight junction protein occludin and zona occludens 1 (ZO-1) expression, and translocation of protein kinase C (PKC)-α after ischemia–reperfusion. A lung ischemia-reperfusion injury model was established in 96 male Wistar rats following the modified Eppinger method. The rats were divided into four groups with 24 rats in each group: a control (group C), an ischemia-reperfusion group (IR group), a sevoflurane control group (sev-C group), and a sevoflurane ischemia-reperfusion group (sev–IR group). There were three time points in each group: ischemic occlusion for 45 min, reperfusion for 60 min and reperfusion for 120 min; and there were six rats per time point. For the 120-min reperfusion group, six extra rats underwent bronchoalveolar lavage. Mean arterial pressure (MAP) and pulse oxygen saturation (SpO2) were recorded at each time point. The wet/dry weight ratio and lung permeability index (LPI) were measured. Quantitative RT-PCR and Western blot were used to measure pulmonary occludin and ZO-1, and Western blot was used to measure cytosolic and membranous PKC-α in the lung. Lung permeability was significantly increased after ischemia–reperfusion. Sevoflurane pretreatment promoted pulmonary expression of occludin and ZO-1 after reperfusion and inhibited the translocation of PKC-α. In conclusion, sevoflurane pretreatment alleviated lung permeability by upregulating occludin and ZO-1 after ischemia–reperfusion. Sevoflurane pretreatment inhibited the translocation and activation of PKC-α, which also contributed to the lung-protective effect of sevoflurane.

Human recombinant apyrase therapy protects against canine pulmonary ischemia-reperfusion injury

There is accumulating evidence that extracellular adenosine triphosphate (eATP) promotes many of the underlying mechanisms that exacerbate acute lung injury. However, much of these data are from inbred rodent models, indicating the need for further investigation in higher vertebrates to better establish clinical relevance. To this end we evaluated a human recombinant apyrase therapy in a canine warm pulmonary ischemia-reperfusion injury (IRI) model and measured eATP levels in human lung recipients with or without primary lung graft dysfunction (PGD). Warm ischemia was induced for 90 minutes in the left lung of 14 mongrel dogs. Seven minutes after reperfusion, the apyrase APT102 (1 mg/kg, n = 7) or saline vehicle (n = 7) was injected into the pulmonary artery. Arterial blood gases were obtained every 30 minutes up to 180 minutes after reperfusion. Bronchioalveolar lavage fluid (BALF) was analyzed for eATP concentration, cellularity, and inflammatory mediator accumulation. Thirty bilateral human lung transplant recipients were graded for immediate early PGD and assessed for BALF eATP levels. APT102-treated dogs had progressively better lung function and less pulmonary edema during the 3-hour reperfusion period compared with vehicle-treated controls. Protection from IRI was observed, with lower BALF eATP levels, fewer airway leukocytes, and blunted inflammatory mediator expression. Human lung recipients with moderate to severe PGD had significantly higher eATP levels compared with recipients without this injury. Extracellular ATP accumulates in acutely injured canine and human lungs. Strategies that target eATP reduction may help protect lung recipients from IRI.

Poster Sessions

Neutrophils infiltrate lung grafts early after reperfusion and are important mediators of primary graft dysfunction. Immune pathways that regulate neutrophil recruitment to lungs during ischemia reperfusion injury remain poorly understood. The purpose of this study was to examine the role of DAP12, an adaptor molecule that regulates innate immune responses, in mediating ischemia reperfusion injury after lung transplantation. We used a mouse model of orthotopic vascularized lung transplantation. Grafts were assessed functionally (arterial blood gases), immunohistochemically, by quantitative PCR, flow cytometry and intravital two-photon imaging. Chemokine production by macrophages in vitro was assessed by ELISA. We found that macrophages in mouse (qPCR and immunohistochemistry) and human (immunohistochemistry) lungs that have been subjected to cold ischemia express DAP12. Donor, but not recipient deficiency in DAP12 protected against pulmonary ischemia reperfusion injury as evidenced by improved graft function (WTàWT, mean paO2=180.8+/-18.9, n=14, DAP12KOàWT, mean paO2=410.8 +/- 36.9, n=8, WTàDAP12KO mean paO2=217.9 +/-55.9, n=7). Compared to wild-type (WT) B6 cells, DAP12KO bone marrow-derived macrophages produced lower amounts of the neutrophil chemoattractant CXCL2 after in vitro stimulation (17 hours) with lysates derived from syngeneic B6 lung transplants (n=2). Similarly, qPCR of sorted donor macrophages 2 hours after reperfusion in vivo revealed significantly lower expression of CXCL2 when DAP12 was absent (n=4). Intravital two-photon imaging using LysM-GFP neutrophil reporter mice as recipients demonstrated a transendothelial migration defect of neutrophils into DAP12KO lungs at 4 hours after reperfusion (percentage of extravascular neutrophils: WTàLysM-GFP=69.3%, n=3; DAP12KOàLysM-GFP=25.6%, n=3). Neutrophil entry into DAP12-deficient lungs was restored when WT bone-marrow derived macrophages (76.8%, n=3) or recombinant CXCL2 (63.3%, n=3) was administered into the donor bronchus prior to reperfusion. Our study has uncovered a previously unrecognized role for DAP12 expression in tissue-resident macrophages in mediating ischemia reperfusion injury after lung transplantation through regulation of neutrophil trafficking.

Prevention of Lung Injury in Cardiac Surgery: A Review

Inflammatory lung injury is an inevitable consequence of cardiac surgery with cardiopulmonary bypass. The lungs are particularly susceptible to the effects of the systemic inflammatory response to cardiopulmonary bypass. This insult is further exacerbated by a pulmonary ischemia–reperfusion injury after termination of bypass. Older patients and those with pre-existing lung disease will clearly be less tolerant of any lung injury and more likely to develop respiratory failure in the postoperative period. A requirement for prolonged ventilation has implications for morbidity, mortality, and cost of treatment. This review contains a summary of recent interventions and changes of practice that may reduce inflammatory lung injury after cardiac surgery. The review also focuses on a number of general aspects of perioperative management, which may exacerbate such injury, if performed poorly.

Protective Effect of Ginsenoside Rb1 Mixing with Several Lung Flush Solutions on Pulmonary Ischemia-Reperfusion Injury

Objective: To evaluate the protective effects of ginsenoside Rb1 mixed with LPD compared to mixed with several other lung flush solutions on ischemia-reperfusion injury. Method: Three group of rabbit lungs were perfused with three kinds of mixtures of ginsenoside Rb1 with blood, Euro-Collins solution(EC) or low-potassium-dextran solution(LPD) respectively, then lung dry/wet weight ratio and malondiadehyde(MAD) were examined and histological changes were observed. Result: Lung dry/wet weight ratio of LPD and Rb1 group was higher than that of EC and Rb1 and blood and Rb1 groups, whereas MAD of LPD and Rb1 group was significantly less than that of EC and Rb1 and blood and Rb1 groups（P<0.05）. Histological findings showed less damage in LPD and Rb1 group. Conclusion: Ginsenoside Rb1 mixed with LPD shows a better protective effect on pulmonary ischemia-reperfusion injury compared with other mixtures.

Postperfusion lung syndrome: physiopathology and therapeutic options.

Postperfusion lung syndrome is rare but can be lethal. The underlying mechanism remains uncertain but triggering inflammatory cascades have become an accepted etiology. A better understanding of the pathophysiology and the roles of inflammatory mediators in the development of the syndrome is imperative in the determination of therapeutic options and promotion of patients' prognosis and survival. Postperfusion lung syndrome is similar to adult respiratory distress syndrome in clinical features, diagnostic approaches and management strategies. However, the etiologies and predisposing risk factors may differ between each other. The prognosis of the postperfusion lung syndrome can be poorer in comparison to acute respiratory distress syndrome due to the secondary multiple organ failure and triple acid-base imbalance. Current management strategies are focusing on attenuating inflammatory responses and preventing from pulmonary ischemia-reperfusion injury. Choices of cardiopulmonary bypass circuit and apparatus, innovative cardiopulmonary bypass techniques, modified surgical maneuvers and several pharmaceutical agents can be potential preventive strategies for acute lung injury during cardiopulmonary bypass.

Temporal determination of lung NO system and COX-2 upregulation following ischemia–reperfusion injury

ABSTRACTBackground: Pulmonary ischemia–reperfusion (IR) is a biopathological event detectable in several clinical conditions, including lung transplantation, cardiopulmonary bypass, resuscitation, and pulmonary embolism. The understanding behind the activation of various inflammatory mediators regulating the apoptotic pathways remains largely unknown. We investigated the temporal expression of endothelial nitric oxide (eNOS), inducible (iNOS), and cyclooxygenase-2 (COX-2) proteins following lung-IR injury. Methods: Lung IR was induced in anesthetized rats. One hour ischemia was performed by clamping the left hilum. eNOS, iNOS, and COX-2 levels in the bronchoalveolar lavage (BAL) were measured at different time points after restoring lung perfusion in conjunction with histological changes and cellular apoptosis. Results: BAL-eNOS levels were increased as early as 3 hours post IR, attaining the highest values (5.5 U/mL) at 3 hours, compared to non-IR values (2.8 U/mL). BAL-iNOS increased at 3-hour post-IR (3 U/mL). iNOS reached the highest levels at 24 hours (4.5 U/mL) as compared to nonischemic lungs (1.8 U/mL). COX-2 peaked at 12 hours (.025 U/mL) compared to 3, 24, and 48 hours. Highest apoptotic rates were detected at 12 and 48 hours following IR. Conclusions: The time-associated involvement of eNOS, iNOS, and COX-2 enzymes during the evolution of IR injury may point to an early reaction of the NOSs system versus the COX-2. Similar patterns of enzymatic activity were previously shown in the context of lung IR injury. This temporal activation may indicate an involvement of eNOS in an early reparative response, and possibly the late-pathological response, mediated by the coinduction of iNOS–COX-2.

α1-Antitrypsin inhibits ischemia reperfusion-induced lung injury by reducing inflammatory response and cell death

Pulmonary ischemia-reperfusion (IR)-induced lung injury is a severe complication that increases the likelihood of primary graft dysfunction and early death after lung transplantation. Inflammatory cytokine release and cell death play a critical role in the development of IR-induced lung injury. α1-Antitrypsin (A1AT) is a protease inhibitor clinically used for the treatment of A1AT-deficiency emphysema. On the basis of a literature review, we hypothesize that A1AT may have the potential to reduce IR-induced lung injury through its anti-inflammatory and anti-apoptotic effects. A human pulmonary cell culture model was used to simulate IR processes in lung transplantation. Effects of A1AT on cell death and cytokine production were examined. A rat pulmonary IR model, in which the left pulmonary hilum was clamped for 90 minutes, followed by reperfusion for 2 hours, was used to determine the effects of A1AT on acute lung injury, function, cell death, and inflammatory response. A1AT significantly inhibited cell death and inflammatory cytokine release dose-dependently in vitro and significantly improved lung oxygenation and lung mechanics and reduced pulmonary edema in vivo. Moreover, A1AT inhibited neutrophil infiltration in the lung and reduced cell death and significantly reduced IR-induced inflammatory mediators in plasma, including interleukin (IL)-1α, IL-4, IL-12p70, monocyte chemotactic protein 1, and tumor necrosis factor-α. Considering its current clinical use, our findings indicate that administration of A1AT may be an effective and safe therapy for the treatment of IR injury in human lung transplantation.

High-Mobility Group Box-1 as a Novel Therapeutic Target for Reducing Pulmonary Ischemia-Reperfusion Injury in CLAWN Miniature Swine

Purpose: Strategies that reduce ischemia-reperfusion injury (IRI) have the potential to expand the use of extended-criteria or donation after cardiac donors and improve both the short and long-term outcomes of transplantation. Because high-mobility group box 1 (HMGB1) has been reported to be a mediator of inflammation and cell injury, blocking of HMGB1 might represent a novel therapeutic strategy against IRI. However, there is limited data to characterize the role of HMGB1 on pulmonary IRI especially in large animals. The aim of this study was to determine the role of HMGB1 on IRI and to evaluate the cytoprotective effects of anti-HMGB1 antibodies as a translational research using our established, in situ porcine lung warm IRI model. Methods: Warm ischemia was induced in 12 CLAWN miniature swine by clamping the left main bronchus, pulmonary artery and veins for 90 minutes. In the control group (n=5), the animals were followed without any additional treatment. In the HMGB1 Ab group (n=4), 1mg/kg of anti-HMGB1 Ab was intravenously injected just before reperfusion. In the isotype Ab group (n=3), control IgY Ab was injected as the same fashion as the HMGB1 Ab group. Lung function and structure were serially accessed via lung biopsy, chest X-ray and blood gas analysis. Serum cytokine levels such as IL-1β and HMGB1 were measured in order to characterize the inflammatory response to IRI and evaluate the effect of the treatment on that response. Results: Serum levels of HMGB1 increased after IRI, peaking 2 days after reperfusion (14 ± 6 ng/ml) in the control group. Anti-HMGB1 Ab treatment resulted in significant reduction of HMGB1 (0.9 ± 0.5 ng/ml). Two hours after reperfusion, the PaO2 of the HMGB1 Ab group was 551 ± 19 mmHg, more than double of the control group (266 ± 60 mmHg). Lung biopsy in the control group showed significant damage to alveolar endothelial cells with intra-alveolar edema, hemorrhage, and fibrin exudates at POD2. In contrast, treatment with anti-HMGB1 Ab resulted in marked improvement of histological findings and less PCNA-positive infiltrating cells and TUNEL-positive apoptotic cells. Systemic IL-1β levels increased after IRI in both the control and HMGB1 groups, peaking 1 day after reperfusion, though there was no difference in the concentration between two groups (control vs. HMGB1 Ab group; 63 ± 26 vs. 62 ± 14 pg/ml). Furthermore, treatment of isotype control IgY Ab showed no effect on improving gas oxygenation or inhibiting lung damage after IRI. Conclusions: In this study, we demonstrated that HMGB1 played a major role in the progression of lung IRI and that reducing systemic HMGB1 by anti-HMGB1 Ab alone could reduce IRI independently of systemic IL-1β concentration using a clinically relevant large animal model. Targeting HMGB1 might represent a novel therapeutic strategy in clinical IRI associated with lung transplantation.

Ischemic postconditioning downregulates Egr-1 expression and attenuates postischemic pulmonary inflammatory cytokine release and tissue injury in rats

BackgroundThe early growth response-1 (Egr-1) gene is upregulated after an ischemia–reperfusion (IR) challenge and upregulates target genes, such as proinflammatory cytokines. Ischemic postconditioning (IPostC) attenuates lung IR injury and reduces the systemic inflammatory response by activating heme oxygenase-1 (HO-1). However, the role of Egr-1 in IPostC protection against lung IR injury and inflammation and its interplay with HO-1 in IPostC protection is unknown. Materials and methodsSprague-Dawley rats or cultured A549 cells were subjected to IR or hypoxia/reoxygenation with or without IPostC or hypoxic postconditioning in the presence or absence of Egr-1 inhibition using Egr-1 antisense oligodeoxyrinonucleotide or Egr-1 small interfering RNA transfection. Lung injury was assessed by measuring the lung wet/dry weight ratio, histologic change, and malondialdehyde content. The amount of lactate dehydrogenase release in culture medium was detected to evaluate cell injury. The protein expression of Egr-1, interleukin (IL)-1β, and HO-1 was assessed by Western blot. ResultsInhibition of Egr-1 significantly attenuated lung IR injury and the inflammation response caused by IR or hypoxia/reoxygenation, as shown by the alleviated lung pathologic changes, decreased pulmonary malondialdehyde content, wet/dry ratio, reduced release of the cytokines tumor necrosis factor-α, IL-6, and IL-8 in the bronchoalveolar lavage, and reduced Egr-1, IL-1β, and HO-1 protein expression and HO-1 activity. IPostC or hypoxic postconditioning reduced the postischemic Egr-1 expression and conferred similar protection against lung IR injury as Egr-1 inhibition. ConclusionsEgr-1 plays an important role in regulating the HO-1 production induced by IR or hypoxia/reoxygenation. Thus, downregulation of Egr-1 expression might represent one of the major mechanisms whereby IPostC confers protection against pulmonary IR insult.

228 Therapeutic Effect of Surfactant Inhalation on Lungs Donated after Cardiac Death in a Canine Lung Transplantation Model

In lung transplantation, donation after cardiac death (DCD) has been introduced worldwide. To date, several programs have reported acceptable outcomes; however, the number of patients on waiting lists is indeed much more than that of the donated organs. Therefore, we considered the effective use of marginal donor grafts from uncontrolled DCD donors by investigating the effect of surfactant inhalation against pulmonary ischemia-reperfusion injury in canine lungs from DCD donors.

Glycine preconditioning to ameliorate pulmonary ischemia reperfusion injury in rats

This study examines the impact of glycine (Gly) preconditioning on ischemia reperfusion (IR)-induced pulmonary mitochondrial injury to research the previously, in pig lungs, demonstrated Gly-dependent amelioration of pulmonary IR injury. IR injury was induced in rat lungs by 30 min pulmonary hilum clamping followed by 60 min reperfusion time. Rats were subjected to controls, shams and two study groups (IR30/60, Gly-IR30/60) receiving 37.5 mg Gly i.v. or not before IR induction. The wet/dry-weight ratio, mitochondria viability (MV), membrane integrity (MI), respiratory chain complex (RCC) activities, mitochondrial membrane potential (ΔΨm) and cytochrome C (Cyt C) content were analysed. In IR30/60, RCC and MV were impaired; Cyt C loss and MI combined with matrix metalloproteinase-9 (MMP-9) activation and ΔΨm alteration were observed when compared with controls. In Gly-IR30/60, complex II function and mitochondrial viability were protected during IR, and MMP-9 activation combined with tissue-water content accumulation and ΔΨm alteration were ameliorated. Cyt C loss, mitochondrial membranes damage, tissue GSH oxidation or neutrophil sequestration was not extenuated in Gly-IR30/60. Gly ameliorates IR-associated mitochondrial dysfunction and decay of viability and normalizes ΔΨm but does not protect from Cyt C liberation and mitochondrial membrane damage. Our data suggest that the previously described effect of Gly preconditioning results at least partially from mitochondrial protection. A dose-finding study is necessary to improve results of Gly preconditioning.

Src tyrosine kinase inhibition prevents pulmonary ischemia–reperfusion-induced acute lung injury

Pulmonary ischemia-reperfusion is a pathological process seen in several clinical conditions, including lung transplantation, cardiopulmonary bypass, resuscitation for circulatory arrest, atherosclerosis, and pulmonary embolism. A better understanding of its molecular mechanisms is very important. Rat left lung underwent in situ ischemia for 60min, followed by 2h of reperfusion. The gene expression profiles and Src protein tyrosine kinase (PTK) phosphorylation were studied over time, and PP2, an Src PTK inhibitor, was intravenously administered 10min before lung ischemia to determine the role of Src PTK in lung injury. Reperfusion following ischemia significantly changed the expression of 169 genes, with Mmp8, Mmp9, S100a9, and S100a8 being the most upregulated genes. Ischemia alone only affected expression of 9 genes in the lung. However, Src PTK phosphorylation (activation) was increased in the ischemic lung, mainly on the alveolar wall. Src PTK inhibitor pretreatment decreased phosphorylation of Src PTKs, total protein tyrosine phosphorylation, and STAT3 phosphorylation. It increased phosphorylation of the p85α subunit of PI3 kinase, a signal pathway that can inhibit coagulation and inflammation. PP2 reduced leukocyte infiltration in the lung, apoptotic cell death, fibrin deposition, and severity of acute lung injury after reperfusion. Src inhibition also significantly reduced CXCL1 (GRO/KI) and CCL2 (MCP-1) chemokine levels in the serum. During pulmonary ischemia, Src PTK activation, rather than alteration in gene expression, may play a critical role in reperfusion-induced lung injury. Src PTK inhibition presents a new prophylactic treatment for pulmonary ischemia-reperfusion-induced acute lung injury.

Dimethylsulfoxide-preconditioning ameliorates pulmonary ischemia-reperfusion injury in rats

Dimethylsulfoxide-preconditioning ameliorates pulmonary ischemia-reperfusion injury in rats

Adenosine A 2A Agonist Improves Lung Function During Ex Vivo Lung Perfusion

Ex vivo lung perfusion (EVLP) is a novel technique than can be used to assess and potentially repair marginal lungs that may otherwise be rejected for transplantation. Adenosine has been shown to protect against pulmonary ischemia-reperfusion (IR) injury through its A(2A) receptor. We hypothesized that combining EVLP with adenosine A(2A) receptor agonist treatment would enhance lung functional quality and increase donor lung use. Eight bilateral pig lungs were harvested and flushed with cold Perfadex (Vitrolife, Englewood, CO). After 14 hours of storage at 4°C, EVLP was performed for 5 hours on 2 explanted lung groups: (1) control group lungs (n = 4) were perfused with Steen Solution (Vitrolife) and dimethyl sulfoxide and (2) treated group lungs (n = 4) received 10 μM CGS21680, a selective A(2A) receptor agonist, in a Steen solution-primed circuit. Lung histologic features, tissue cytokines, gas analysis, and pulmonary function were compared between groups. Treated lungs demonstrated significantly less edema as reflected by wet-dry weight ratio (6.6 versus 5.2; p < 0.03) and confirmed by histologic examination. In addition, treated lung demonstrated significantly lower levels of interferon-γ (IFN- γ) (45.1 versus 88.5; p < 0.05). Other measured tissue cytokine levels (interleukin [IL]-1β, IL-6, and IL-8) were lower in the treatment group, but values failed to reach statistical significance. The oxygenation index was improved in the treated group (1.5 versus 2.3; p < 0.01) as was mean airway pressure (10.3 versus 13; p < 0.009). Combined use of adenosine A(2A) agonist and EVLP significantly attenuates the inflammatory response in acutely injured lungs after IR and enhances pulmonary function. This combination may improve donor lung quality and could increase the donor lung pool for transplantation.

Resveratrol Ameliorates Mitochondrial and Tissue Damage in Pulmonary Ischemia Reperfusion Injur

PURPOSE: We have demonstrated impaired mitochondrial viability and function during pulmonary ischemia reperfusion injury(IR). Resveratrol(Res) has demonstrated to ameliorate the IR of various organs. This study analyzes the impact of Res-preconditioning on pulmonary IR-induced mitochondrial dysfunction and tissue damage.

Autologous Transplantation of Adipose-Derived Mesenchymal Stem Cells Markedly Reduced Acute Ischemia-Reperfusion Lung Injury in a Rodent Model

BackgroundThis study tested the hypothesis that autologous transplantation of adipose-derived mesenchymal stem cells (ADMSCs) can effectively attenuate acute pulmonary ischemia-reperfusion (IR) injury.MethodsAdult male Sprague-Dawley (SD) rats (n = 24) were equally randomized into group 1 (sham control), group 2 (IR plus culture medium only), and group 3 (IR plus intravenous transplantation of 1.5 × 106 autologous ADMSCs at 1h, 6h, and 24h following IR injury). The duration of ischemia was 30 minutes, followed by 72 hours of reperfusion prior to sacrificing the animals. Blood samples were collected and lungs were harvested for analysis.ResultsBlood gas analysis showed that oxygen saturation (%) was remarkably lower, whereas right ventricular systolic pressure was notably higher in group 2 than in group 3 (all p < 0.03). Histological scoring of lung parenchymal damage was notably higher in group 2 than in group 3 (all p < 0.001). Real time-PCR demonstrated remarkably higher expressions of oxidative stress, as well as inflammatory and apoptotic biomarkers in group 2 compared with group 3 (all p < 0.005). Western blot showed that vascular cell adhesion molecule (VCAM)-1, intercellular adhesion molecule (ICAM)-1, oxidative stress, tumor necrosis factor-α and nuclear factor-κB were remarkably higher, whereas NAD(P)H quinone oxidoreductase 1 and heme oxygenase-1 activities were lower in group 2 compared to those in group 3 (all p < 0.004). Immunofluorescent staining demonstrated notably higher number of CD68+ cells, but significantly fewer CD31+ and vWF+ cells in group 2 than in group 3.ConclusionADMSC therapy minimized lung damage after IR injury in a rodent model through suppressing oxidative stress and inflammatory reaction.

Glutathione preconditioning ameliorates mitochondria dysfunction during warm pulmonary ischemia–reperfusion injury

Reduced glutathione (GSH) has been shown to improve pulmonary graft preservation. Mitochondrial dysfunction is regarded to be the motor of ischemia-reperfusion injury (IR) in solid organs. We have shown previously that IR induces pulmonary mitochondrial damage. This study elucidates the impact of GSH preconditioning on the integrity and function of pulmonary mitochondria in the setting of warm pulmonary IR. Wistar rats were subjected to control, sham, and to two-study-group conditions (IR30/60 and GSH-IR30/60) receiving IR with or without GSH preconditioning. Rats were anesthetized and received mechanical ventilation. Pulmonary in situ clamping followed by reperfusion generated IR. Mitochondria were isolated from pulmonary tissue. Respiratory chain complexes activities (I-IV) were analyzed by polarography. Mitochondrial viability (Ca2+-induced swelling) and membrane integrity (citrate synthase assay) were determined. Subcellular-fractional cytochrome C-content (Cyt C) was quantified by enzyme-linked immunosorbent assay (ELISA). Mitochondrial membrane potential (ΔΨm) was analyzed by fluorescence-activated cell sorting (FACS) after energizing and uncoupling. Inflammatory activation was determined by myeloperoxidase activity (MPO), matrix-metalloproteinase 9 (MMP-9) activity by gel zymography. Pulmonary IR significantly reduced mitochondrial viability in combination with ΔΨm hyper-polarization. GSH preconditioning improved mitochondrial viability and normalized ΔΨm. Cyt C was reduced after IR; GSH protected from Cyt C liberation. Respiratory chain complex activities (I, II, III) declined during IR; GSH protected complex II function. GSH also protected from MMP-9 and neutrophil sequestration (P>.05). GSH preconditioning is effective to prevent mitochondrial death and improves complex II function during IR, but not mitochondrial membrane stability. GSH-mediated amelioration of ΔΨm hyper-polarization appears to be the key factor of mitochondrial protection.

Therapeutic strategy for acute respiratory distress syndrome: recent understanding of the pathophysiology of the disease

Acute respiratory distress syndrome (ARDS) features acute onset, severe hypoxemia, bilateral infiltrates documented by chest radiograph, and the absence of left atrial hypertension. Factors that lead to this syndrome vary from direct lung damage, including respiratory infection, aspiration, inhalation of chemical or poisonous gas, pulmonary contusion, and pulmonary ischemia–reperfusion, to indirect causes including sepsis, acute pancreatitis, severe trauma, cardiopulmonary bypass, and transfusion. Epidemiology of ARDS