[Show abstract][Hide abstract] ABSTRACT: Aims: Ventilator-induced lung injury (VILI) contributes to mortality in patients with acute respiratory distress syndrome, the clinical form of acute lung injury (ALI). Absence of activating transcription factor 3 (ATF3) confers susceptibility to ALI/VILI. To identify cell-specific ATF3-dependent mechanisms of susceptibility to ALI/VILI, we generated ATF3 chimera by adoptive bone marrow transfer and randomized to inhaled saline or lipopolysacharide (LPS) in the presence of mechanical ventilation (MV). Adenovirus vectors to silence or overexpress ATF3 were used in primary human bronchial epithelial cells and murine bone marrow derived macrophages from wild type or ATF3 deficient mice. Results: Absence of ATF3 in myeloid cells caused increased pulmonary cellular infiltration. In contrast, absence of ATF3 in parenchymal cells resulted in loss of alveolar-capillary membrane integrity and increased edema. ATF3-deficient macrophages were unable to limit the expression of pro-inflammatory mediators. Knockdown of ATF3 in resident cells resulted in decreased junctional protein expression and increased leak. ATF3 overexpression abrogated LPS induced membrane permeability. Despite release of ATF3-dependent Nrf2 transcriptional inhibition, mice that lacked ATF3 in resident cells had increased Nrf2 protein degradation. Innovation: In our model, in the absence of ATF3 in parenchymal cells increased Nrf2 degradation is the result of increased Keap-1 expression and loss of DJ-1 (Parkinson disease [autosomal recessive, early onset] 7), previously not known to play a role in lung injury. Conclusion: Results suggest ATF3 confers protection to lung injury by preventing inflammatory cell recruitment and barrier disruption in a cell-specific manner opening novel opportunities for cell specific therapy for ALI/VILI.
[Show abstract][Hide abstract] ABSTRACT: Osteopontin (OPN) is a multifunctional glycoprotein with pro-inflammatory properties. In severe sepsis, levels of plasma OPN are significantly higher in non-survivors than in survivors. We hypothesized that OPN results in greater inflammation and worse outcome through modulation of endogenous glucocorticoid production in sepsis.
[Show abstract][Hide abstract] ABSTRACT: Intratracheal aspiration and sepsis are leading causes of acute lung injury that frequently necessitate mechanical ventilation (MV), which may aggravate lung injury thereby potentially increasing the risk of acute kidney injury (AKI). We compared the effects of ventilation strategies and underlying conditions on the development of AKI.
[Show abstract][Hide abstract] ABSTRACT: Experimental work provides insight into potential lung protective strategies. The objective of this study was to evaluate markers of ventilator-induced lung injury after two different ventilation approaches: (1) a "conventional" lung-protective strategy (volume control (VC) with low tidal volume, positive end-expiratory pressure (PEEP) and paralysis), (2) a physiological approach with spontaneous breathing, permitting synchrony, variability and a liberated airway. For this, we used non-invasive Neurally Adjusted Ventilatory Assist (NIV-NAVA), with the hypothesis that liberation of upper airways and the ventilator's integration with lung protective reflexes would be equally lung protective.
In this controlled and randomized in vivo laboratory study, 25 adult White New Zealand rabbits were studied. There were five non-ventilated control animals. There were 20 with HCl aspiration-induced studied, including five non-ventilated control animals. Twenty animals with aspiration-induced lung injury were randomized lung injury and they were randomized to ventilation with either VC (6 mL/kg, PEEP 5 cmH2O, and paralysis) or NIV-NAVA for six hours (PEEP = zero because of leaks). Markers of lung function, lung injury, vital signs and ventilator parameters were assessed.
At the end of six hours of ventilation (n = 20), there were no significant differences between VC and NIV-NAVA for vital signs, PaO2/FiO2 ratio, lung wet-to-dry ratio and brocho-alveolar Interleukin 8 (Il-8). Plasma IL-8 was higher in VC (P <0.05). Lung injury score was lower for NIV-NAVA (P = 0.03). Dynamic lung compliance recovered after six hours in NIV-NAVA but not in VC (P <0.05). During VC, peak pressures increased from 9.2 +/- 2.4 cm H2O (hour 1) to 12.3 +/- 12.3 cm H2O (hour 6) (P <0.05). During NIV-NAVA, the tracheal end-expiratory pressure was similar to the end-expiratory pressure during VC. Two animals regurgitated during NIV-NAVA, without clinical consequences, and survived the protocol.
In experimental acute lung injury, NIV-NAVA is as lung-protective as VC 6 ml/kg with PEEP.
Critical care (London, England) 01/2014; 18(1):R22. · 4.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although bone marrow-derived mesenchymal stem cell (MSC) systemic administration reduces sepsis-associated inflammation, organ injury, and mortality in clinically relevant models of polymicrobial sepsis, the cellular and molecular mechanisms mediating beneficial effects are controversial. This study identifies the molecular mechanisms of MSC-conferred protection in sepsis by interrogating transcriptional responses of target organs to MSC therapy. Sepsis was induced in C57Bl/6J mice by cecal ligation and puncture, followed 6 hours later by an i.v. injection of either MSCs or saline. Total RNA from lungs, hearts, kidneys, livers, and spleens harvested 28 hours after cecal ligation and puncture was hybridized to mouse expression bead arrays. Common transcriptional responses were analyzed using a network knowledge-based approach. A total of 4751 genes were significantly changed between placebo- and MSC-treated mice (adjusted P ≤ 0.05). Transcriptional responses identified three common effects of MSC administration in all five organs examined: i) attenuation of sepsis-induced mitochondrial-related functional derangement, ii down-regulation of endotoxin/Toll-like receptor innate immune proinflammatory transcriptional responses, and iii) coordinated expression of transcriptional programs implicated in the preservation of endothelial/vascular integrity. Transcriptomic analysis indicates that the protective effect of MSC therapy in sepsis is not limited to a single mediator or pathway but involves a range of complementary activities affecting biological networks playing critical roles in the control of host cell metabolism and inflammatory response.
American Journal Of Pathology 11/2012; 181(5):1681-92. · 4.60 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter through activation of GABA receptors. Volatile anesthetics activate type-A (GABA(A)) receptors resulting in inhibition of synaptic transmission. Lung epithelial cells have been recently found to express GABA(A) receptors that exert anti-inflammatory properties. We hypothesized that the volatile anesthetic sevoflurane (SEVO) attenuates lung inflammation through activation of lung epithelial GABA(A) receptors.
Sprague-Dawley rats were anesthetized with SEVO or ketamine/xylazine (KX). Acute lung inflammation was induced by intratracheal instillation of endotoxin, followed by mechanical ventilation for 4 h at a tidal volume of 15 mL/kg without positive end-expiratory pressure (two-hit lung injury model). To examine the specific effects of GABA, healthy human lung epithelial cells (BEAS-2B) were challenged with endotoxin in the presence and absence of GABA with and without addition of the GABA(A) receptor antagonist picrotoxin.
Anesthesia with SEVO improved oxygenation and reduced pulmonary cytokine responses compared to KX. This phenomenon was associated with increased expression of the π subunit of GABA(A) receptors and glutamic acid decarboxylase (GAD). The endotoxin-induced cytokine release from BEAS-2B cells was attenuated by the treatment with GABA, which was reversed by the administration of picrotoxin.
Anesthesia with SEVO suppresses pulmonary inflammation and thus protects the lung from the two-hit injury. The anti-inflammatory effect of SEVO is likely due to activation of pulmonary GABA(A) signaling pathways.
European Journal of Intensive Care Medicine 06/2012; 38(9):1548-55. · 5.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We hypothesized that resveratrol administration would reverse sepsis-dependent downregulation of peroxisome proliferator activated receptor-γ coactivator 1α, preserve mitochondrial integrity, and rescue animals from sepsis-induced myocardial failure.
Teaching hospital research laboratory.
Cecal ligation and puncture in mice was performed to induce sepsis. Mice that underwent cecal ligation and puncture were randomly assigned to receive resveratrol (30 mg/kg or 60 mg/kg) or vehicle 1 mL sodium chloride 0.9% subcutaneously in the scruff of the neck directly after surgery and at 16, 24, and 40 hrs, respectively.
Forty-eight hrs after cecal ligation and puncture, cardiac performance was established using echocardiography. Mitochondrial integrity was evaluated with electron microscopy, and changes in gene expression were evaluated with microarray analysis. Survival at 48 hrs was just under 50% and comparable between groups. Myocardial contractile function significantly improved after resveratrol treatment. Resveratrol-treated mice developed focal areas of edema, whereas vehicle-treated mice developed significant, diffuse myocardial edema. Electron microscopy revealed widespread swollen mitochondria with ruptured outer membranes, autophagosomes, and vacuolation of the internal compartment, which were significantly attenuated in resveratrol-treated animals. Resveratrol treatment significantly increased cardiac expression of peroxisome proliferator-activated receptor-γ coactivator 1a. Microarray analysis revealed that resveratrol treatment resulted in upregulation of the peroxisome proliferator-activated receptor-γ coactivator gene set containing genes known to be regulated by this transcriptional coactivator. Our data strongly suggest that administration of resveratrol modulates bioenergy metabolism, substrate utilization, oxidative stress, and detoxification pathways associated with both mitochondrial and cardiac pathological conditions, but does not alter mortality from sepsis.
The salutary effects of resveratrol on cecal ligation and puncture-induced myocardial dysfunction are associated with increased peroxisome proliferator-activated receptor-γ coactivator 1a abundance and function. Preservation of myocardial energy production capacity, prevention of secondary injury, mitigation of inflammation, and reversal of sepsis-induced myocardial remodeling are likely to underlie its beneficial effects. This however, does not result in improved survival.
Critical care medicine 06/2012; 40(6):1896-907. · 6.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mechanical ventilation exaggerates pneumonia-associated pulmonary coagulopathy and inflammation. We hypothesized that the administration of plasma-derived human antithrombin (AT), one of the natural inhibitors of coagulation, prevents ventilator-induced pulmonary coagulopathy, inflammation and bacterial outgrowth in a Streptococcus pneumoniae pneumonia model in rats.
Forty-eight hours after induction of S. pneumoniae pneumonia rats were subjected to mechanical ventilation (tidal volume 12 mL kg(-1), positive end-expiratory pressure 0 cmH(2)O and inspired oxygen fraction 40%). Rats were randomized to systemic treatment with AT (250 IU administered intravenously (i.v.) before the start of mechanical ventilation) or placebo (saline). Non-ventilated, non-infected rats and non-ventilated rats with pneumonia served as controls. The primary endpoints were pulmonary coagulation and inflammation in bronchoalveolar lavage fluid (BALF).
Pneumonia was characterized by local activation of coagulation and inhibition of fibrinolysis, resulting in increased levels of fibrin degradation products and fibrin deposition in the lung. Mechanical ventilation exaggerated pulmonary coagulopathy and inflammation. Systemic administration of AT led to supra-normal BALF levels of AT and decreased ventilator-associated activation of coagulation. AT neither affected pulmonary inflammation nor bacterial outgrowth from the lungs or blood.
Plasma-derived human AT attenuates ventilator-induced coagulopathy, but not inflammation and bacterial outgrowth in a S. pneumoniae pneumonia model in rats.
Journal of Thrombosis and Haemostasis 03/2012; 10(3):399-410. · 6.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To perform a meta-analysis of gene expression microarray data from animal studies of lung injury, and to identify an injury-specific gene expression signature capable of predicting the development of lung injury in humans.
We performed a microarray meta-analysis using 77 microarray chips across six platforms, two species and different animal lung injury models exposed to lung injury with or/and without mechanical ventilation. Individual gene chips were classified and grouped based on the strategy used to induce lung injury. Effect size (change in gene expression) was calculated between non-injurious and injurious conditions comparing two main strategies to pool chips: (1) one-hit and (2) two-hit lung injury models. A random effects model was used to integrate individual effect sizes calculated from each experiment. Classification models were built using the gene expression signatures generated by the meta-analysis to predict the development of lung injury in human lung transplant recipients.
Two injury-specific lists of differentially expressed genes generated from our meta-analysis of lung injury models were validated using external data sets and prospective data from animal models of ventilator-induced lung injury (VILI). Pathway analysis of gene sets revealed that both new and previously implicated VILI-related pathways are enriched with differentially regulated genes. Classification model based on gene expression signatures identified in animal models of lung injury predicted development of primary graft failure (PGF) in lung transplant recipients with larger than 80% accuracy based upon injury profiles from transplant donors. We also found that better classifier performance can be achieved by using meta-analysis to identify differentially-expressed genes than using single study-based differential analysis.
Taken together, our data suggests that microarray analysis of gene expression data allows for the detection of "injury" gene predictors that can classify lung injury samples and identify patients at risk for clinically relevant lung injury complications.
PLoS ONE 01/2012; 7(10):e45506. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To examine whether acute lung injury from direct and indirect origins differ in susceptibility to ventilator-induced lung injury (VILI) and resultant systemic inflammatory responses.
Rats were challenged by acid instillation or 24 h of sepsis induced by cecal ligation and puncture, followed by mechanical ventilation (MV) with either a low tidal volume (Vt) of 6 mL/kg and 5 cm H2O positive end-expiratory pressure (PEEP; LVt acid, LVt sepsis) or with a high Vt of 15 mL/kg and no PEEP (HVt acid, HVt sepsis). Rats sacrificed immediately after acid instillation and non-ventilated septic animals served as controls. Hemodynamic and respiratory variables were monitored. After 4 h, lung wet to dry (W/D) weight ratios, histological lung injury and plasma mediator concentrations were measured.
Oxygenation and lung compliance decreased after acid instillation as compared to sepsis. Additionally, W/D weight ratios and histological lung injury scores increased after acid instillation as compared to sepsis. MV increased W/D weight ratio and lung injury score, however this effect was mainly attributable to HVt ventilation after acid instillation. Similarly, effects of HVt on oxygenation were only observed after acid instillation. HVt during sepsis did not further affect oxygenation, compliance, W/D weight ratio or lung injury score. Plasma interleukin-6 and tumour necrosis factor-α concentrations were increased after acid instillation as compared to sepsis, but plasma intercellular adhesion molecule-1 concentration increased during sepsis only. In contrast to lung injury parameters, no additional effects of HVt MV after acid instillation on plasma mediator concentrations were observed.
During MV more severe lung injury develops after acid instillation as compared to sepsis. HVt causes VILI after acid instillation, but not during sepsis. However, this differential effect was not observed in the systemic release of mediators.
[Show abstract][Hide abstract] ABSTRACT: Ventilator-induced lung injury (VILI) contributes to the mortality in patients with acute lung injury by increasing inflammation. Recent evidence suggests that stimulation of the cholinergic antiinflammatory pathway may be an attractive way to attenuate inflammatory injury.
To determine the role of vagus nerve signaling in VILI and establish whether stimulation of the vagus reflex can mitigate VILI.
We performed bilateral vagotomy in a mouse model of high-tidal volume-induced lung injury. We performed pharmacological and electrical vagus nerve stimulation in a rat model of VILI following ischemia/reperfusion injury. To determine the contribution of the alpha 7 acetylcholine nicotinic receptor to pulmonary cell injury, we exposed human bronchial epithelial cells to cyclic stretch in the presence of specific agonist or antagonist of the alpha 7 receptor.
Vagotomy exacerbates lung injury from VILI in mice as demonstrated by increased wet-to-dry ratio, infiltration of neutrophils, and increased IL-6. Vagal stimulation attenuates lung injury in rats after ischemia/reperfusion injury ventilated with high-volume strategies. Treatment of both mice and rats with the vagus mimetic drug semapimod resulted in decreased lung injury. Vagotomy also increased pulmonary apoptosis, whereas vagus stimulation (electrical and pharmacological) attenuated VILI-induced apoptosis. In vitro studies suggest that vagus-dependent effects on inflammation and apoptosis are mediated via the α7 nicotinc acetylcholine receptor-dependent effects on cyclic stretch-dependent signaling pathways c-jun N-terminal kinase and tumor necrosis factor receptor superfamily, member 6.
Stimulation of the cholinergic antiinflammatory reflex may represent a promising alternative for the treatment of VILI.
American Journal of Respiratory and Critical Care Medicine 02/2011; 183(4):471-82. · 11.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: It has become clear from experimental data that prolonged mechanical ventilation can induce diaphragm dysfunction, also known as ventilator-induced diaphragm dysfunction. In this article we will discuss most recent understanding on ventilator-induced diaphragm dysfunction and data on diaphragm dysfunction in patients.
Over the last year several studies confirmed the existence of diaphragm dysfunction in patients. Known atrophy pathways are activated in patients undergoing prolonged conventional ventilation resulting in muscle proteolysis and a decrease in myofiber content. The loss of diaphragm force is time-dependent, but current data do not distinguish between the role played by other factors involved in diaphragm dysfunction.
Diaphragm dysfunction occurs in patients, especially when ventilated with controlled modes of ventilation that minimize diaphragm activity. Time on the ventilator seems to be one of the biggest risk factors resulting in difficulties in weaning patients and prolonging time on the ventilator. Future trials should investigate whether improved patient-ventilator synchrony can reduce ventilator-induced diaphragm dysfunction and decrease weaning failure.
Current opinion in anaesthesiology 02/2011; 24(2):214-8.
[Show abstract][Hide abstract] ABSTRACT: Long pentraxin PTX3 is an inflammatory mediator and a component of the humoral arm of innate immunity. PTX3 expression is increased in animals with acute lung injury (ALI) and in patients with sepsis or acute respiratory distress syndrome and is considered to be a potential biomarker for these diseases. However, the role of PTX3 in the pathogenesis of ALI is not fully understood. We hypothesized that PTX3, as an important immune modulator, may determine the severity of ALI.
Lipopolysaccharide (LPS) was intra-tracheally administrated to PTX3 knock-out (PTX3-KO) and wild-type (WT) mice. Lung injury, neutrophil infiltration, cell death, fibrin deposition, and tissue factor expression in the lung were determined. Local and systemic inflammatory responses were assessed by measuring cytokines in the lung and plasma.
LPS instillation induced ALI in both PTX3-KO and WT mice. Interestingly, PTX3 deficiency significantly increased the magnitude/extent of lung injury compared to that in WT mice. The severe lung injury was accompanied by elevated neutrophil infiltration, cell death, and fibrin deposition in the lung. PTX3 deficiency also enhanced LPS-induced tissue factor expression/activation in the lung and increased tumor necrosis factor-alpha and monocyte chemoattractant protein-1 levels in the plasma.
Our data suggest that the endogenously expressed PTX3 plays a protective role in the pathogenesis of ALI and that a lack of PTX3 may enhance neutrophil recruitment, cell death, activation of coagulation cascades, and inflammatory responses in the lung.
European Journal of Intensive Care Medicine 11/2010; 37(2):334-42. · 5.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Sepsis refers to the clinical syndrome of severe systemic inflammation precipitated by infection. Despite appropriate antimicrobial therapy, sepsis-related morbidity and mortality remain intractable problems in critically ill patients. Moreover, there is no specific treatment strategy for the syndrome of sepsis-induced multiple organ dysfunction.
We hypothesized that mesenchymal stem cells (MSCs), which have been shown to have immunomodulatory properties, would reduce sepsis-induced inflammation and improve survival in a polymicrobial model of sepsis.
Sepsis was induced in C57Bl/6J mice by cecal ligation and puncture (CLP), followed 6 hours later by an intravenous injection of MSCs or saline. Twenty-eight hours after CLP, plasma, bronchoalveolar lavage fluid and tissues were collected for analyses. Longer-term studies were performed with antibiotic coadministration to assess the effect of MSCs on survival.
MSC treatment significantly reduced mortality in septic mice receiving appropriate antimicrobial therapy. MSCs alone reduced systemic and pulmonary cytokine levels in mice with CLP-induced sepsis, preventing acute lung injury and organ dysfunction, despite the low levels of cell persistence. Microarray data highlighted an overall down-regulation of inflammation and inflammation-related genes (such as IL-10, IL-6) and a shift toward up-regulation of genes involved in promoting phagocytosis and bacterial killing. Finally, bacterial clearance was significantly greater in MSC-treated mice, in part due to enhanced phagocytotic activity of the host immune cells.
These data demonstrate that MSCs have beneficial effects on experimental sepsis, possibly by paracrine mechanisms, and suggest that immunomodulatory cell therapy may be an effective adjunctive treatment to reduce sepsis-related morbidity and mortality.
American Journal of Respiratory and Critical Care Medicine 10/2010; 182(8):1047-57. · 11.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Ventilator-induced lung injury (VILI) significantly contributes to mortality in patients with acute respiratory distress syndrome, the most severe form of acute lung injury. Understanding the molecular basis for response to cyclic stretch (CS) and its derangement during high-volume ventilation is of high priority.
To identify specific molecular regulators involved in the development of VILI.
We undertook a comparative examination of cis-regulatory sequences involved in the coordinated expression of CS-responsive genes using microarray analysis. Analysis of stretched versus nonstretched cells identified significant enrichment for genes containing putative binding sites for the transcription factor activating transcription factor 3 (ATF3). To determine the role of ATF3 in vivo, we compared the response of ATF3 gene-deficient mice to wild-type mice in an in vivo model of VILI.
ATF3 protein expression and nuclear translocation is increased in the lung after mechanical ventilation in wild-type mice. ATF3-deficient mice have greater sensitivity to mechanical ventilation alone or in conjunction with inhaled endotoxin, as demonstrated by increased cell infiltration and proinflammatory cytokines in the lung and bronchoalveolar lavage, and increased pulmonary edema and indices of tissue injury. The expression of stretch-responsive genes containing putative ATF3 cis-regulatory regions was significantly altered in ATF3-deficient mice.
ATF3 deficiency confers increased sensitivity to mechanical ventilation alone or in combination with inhaled endotoxin. We propose ATF3 acts to counterbalance CS and high volume-induced inflammation, dampening its ability to cause injury and consequently protecting animals from injurious CS.
American Journal of Respiratory and Critical Care Medicine 04/2010; 182(4):489-500. · 11.04 Impact Factor