Endotoxin-induced Lung Injury Research Articles

Dexamethasone attenuated endotoxin-induced acute lung injury through inhibiting expression of inducible nitric oxide synthase

Application of glucocorticoids in sepsis or severe infection is disputable in clinic. In this experiment, we studied the effect of dexamethasone on nitric oxide synthases and whether dexamethasone could attenuate endotoxin-induced acute lung injury (ALI). SD rats received 5 mg/kg lipopolisaccharide (LPS) injection. Then arterial oxygen partial pressure (PaO2), lung histology, lung tissue nitric oxide (NO) production and expression of nitric oxide synthases (NOS) were detected at 0.5, 1, 2, 3 or 4 h after LPS injection. PaO2 and lung injury deteriorated upon time. Production of NO in lung tissue increased significantly particularly in the first two hours, and this change was mainly due to the over-expression of inducible NOS (iNOS), but not endothelial NOS (eNOS). Furthermore, a tight positive correlation was observed between lung injury score (LIS) and NO production level in lung tissue. Dexamethasone could ameliorate PaO2 and lung damage evidently, which were paralleled by significant decreases in the production of NO and in the expression of iNOS mRNA. In conclusion, dexamethasone could effectively attenuate endotoxin-induced lung injury through inhibiting iNOS expression and activation in the very early stage of ALI.

Inhaled aerosolised recombinant human activated protein C ameliorates endotoxin-induced lung injury in anaesthetised sheep

IntroductionWe recently demonstrated that intravenously infused recombinant human activated protein C (APC) attenuates ovine lipopolysaccharide (LPS)-induced lung injury. In this study, our aim was to find out whether treatment with inhaled aerosolised APC (inhAPC) prevents formation of increased lung densities and oedema and derangement of oxygenation during exposure to LPS.MethodsSheep were anaesthetised during placement of intravascular introducers. After one to four days of recovery from instrumentation, the animals were re-anaesthetised, endotracheally intubated and mechanically ventilated throughout a six-hour experiment where the sheep underwent quantitative lung computed tomography. Sheep were randomly assigned to one of three groups: a sham-operated group (n = 8) receiving inhaled aerosolised saline from two hours after the start of the experiment; a LPS group (n = 8) receiving an intravenous infusion of LPS 20 ng/kg per hour and, after two hours, inhaled aerosolised saline over the next four hours; a LPS+inhAPC group (n = 8) receiving an intravenous infusion of LPS 20 ng/kg per hour and, after two hours, aerosolised APC 48 μg/kg per hour inhaled throughout the experiment. Data were analysed with analysis of variance; P less than 0.05 was regarded as significant.ResultsAn infusion of LPS was associated with a reduction of well-aerated lung volume and a rapid fall in arterial oxygenation that were both significantly antagonised by inhaled APC. Pulmonary vascular pressures and extravascular lung water index increased significantly during exposure to LPS, but inhaled APC had no effect on these changes.ConclusionsInhalation of aerosolised APC attenuates LPS-induced lung injury in sheep by preventing a decline in the volume of aerated lung tissue and improving oxygenation.

Exogenous Surfactant Suppresses Inflammation in Experimental Endotoxin-Induced Lung Injury

Our objective was to evaluate the anti-inflammatory effects of exogenous surfactant and surfactant phospholipids on the lipopolysaccharide (LPS)-induced lung injury. Exogenous surfactant (porcine surfactant) and surfactant phospholipid (dipalmitoyl phospholipid DPPC, hexadecanol, tylaxopol) were instilled intratracheally with LPS in rats. Expression of surfactant apoproteins (SP-A) and the cyclooxygenase enzymes (COX-1 and -2) was studied by immunohistochemistry, and apoptosis was analyzed by in situ terminal dUTP nick end labeling TUNEL assay. The intracellular reactive oxygen species (ROS) was measured in the isolated macrophages by fluorescence measurement with dichlorofluorescein diacetate (DCFH-DA). LPS-induced oxidative burst and apoptosis at 72 hours were reduced by both porcine and synthetic surfactant. SP-A as well as COX-1 and -2 expressions were suppressed with synthetic surfactant treatment, whereas with porcine surfactant (P-SF) the SP-A expression was enhanced in response to LPS administration. These results indicate that exogenous surfactant inhibits LPS-induced inflammation. This anti-inflammatory activity may be an important outcome of surfactant therapy in endotoxin-induced respiratory distress.

Activated Protein C Protection from Lung Inflammation in Endotoxin-Induced Injury

We studied the protection of recombinant human activated protein C (rhAPC) in endotoxin-induced lung inflammation and injury and whether this effect is correlated with modulation of lung matrix metalloproteinase (MMP) activity. We randomly assigned 12 Large White pigs to receive intravenous Escher-ichia coli lipopolysaccharide (LPS; 40 mu g/kg/hr), rhAPC (24 mu g/ kg/hr), or both. We monitored respiratory mechanics and function, cell counts, and cytokine concentrations in bron-choalveolar lavage fluid (BALF). Lung samples were collected for the zymography of MMP-2 and MMP-9 activities and for histology. In septic pigs, rhAPC decreased proMMP-9 release as well as MMP-9 activation, and increased proMMP-2 presence without any evident activation compared with specimens that were given LPS alone. In addition, lung injury in rhAPC-treated animals was significantly attenuated, as shown by higher respiratory compliance, delayed increase in tumor necrosis alfa and interleukin-1beta as well as neutrophil recruitment in the BALF, reduced lung edema, and histologic changes. In conclusion, rhAPC is beneficial in acute lung injury, and the protection may depend, at least in part, on modulation of MMP-2/9 activity.

Hypercapnic Acidosis Attenuates Lung Injury Induced by Established Bacterial Pneumonia

Hypercapnic acidosis protects against lung injury after ischemia-reperfusion, endotoxin-induced and ventilation-induced lung injury. The effects of hypercapnic acidosis in the setting of established pulmonary sepsis are not known. The authors investigated whether hypercapnic acidosis -- induced by adding carbon dioxide to inspired gas -- would be beneficial or deleterious in established Escherichia coli pneumonia in an in vivo model, in the presence and absence of antibiotic therapy. Adult male Sprague-Dawley rats were anesthetized and ventilated. In the first set of experiments, rats were anesthetized, E. coli (5-6.4 x 10(9)/ml colony-forming units) was instilled intratracheally, and the animals were allowed to recover. After 6 h, during which time a severe pneumonia developed, they were reanesthetized and randomly assigned to normocapnia (fraction of inspired carbon dioxide [Fico(2)] = 0.00, n = 10) or hypercapnic acidosis (Fico(2) = 0.05, n = 10). The second set of experiments was performed in a manner identical to that of series 1, but all rats (n = 10 per group) were given intravenous ceftriaxone (30 mg/kg) at randomization. All animals received normocapnia or hypercapnic acidosis for 6 h, and the severity of lung injury was assessed. In the absence of antibiotic therapy, hypercapnic acidosis reduced the pneumonia-induced increase in peak airway pressure and the decrease in static lung compliance compared with control conditions. In the presence of antibiotic therapy, which substantially reduced lung bacterial counts, hypercapnic acidosis significantly attenuated the extent of pneumonia-induced histologic injury. Hypercapnic acidosis reduced the magnitude of the lung injury induced by established E. coli pneumonia.

Role of Soluble Receptor for Advanced Glycation End Products on Endotoxin-induced Lung Injury

The interaction of receptor for advanced glycation end products (RAGE) and its ligands often leads to inflammatory processes or tissue injury, although the effect of the blockade of RAGE signaling on lung injury remains to be investigated. Using a murine model of lung injury induced by intratracheal lipopolysaccharide (LPS), we evaluated RAGE expression in the airspace and the effect of recombinant soluble RAGE (sRAGE) on LPS-induced lung injury. First, the expression of sRAGE in bronchoalveolar lavage (BAL) fluid was determined at 24 hours after intratracheal instillation of LPS or phosphate-buffered saline. Next, to evaluate the effect of sRAGE, BAL fluid was collected for cell counting and measurements of lung permeability and cytokine concentrations 24 hours after intratracheal LPS in the mice with or without intraperitoneal administration of sRAGE 1 hour after the instillation. In another series, lungs were sampled for histopathology and detection of apoptotic cells. The activation of nuclear factor (NF)-kappaB was analyzed 4 hours after LPS instillation. In response to LPS challenge, a RAGE isoform of 48 kD was detected in the BAL fluid. Treatment with sRAGE significantly attenuated the increases in neutrophil infiltration, lung permeability, production of inflammatory cytokines, NF-kappaB activation, and apoptotic cells in the lung as well as development of pathologic changes after LPS instillation. RAGE plays an important role in the pathogenesis of LPS-induced lung injury in mice. It was suggested that sRAGE should be tested as a treatment modality in other models of acute lung injury.

Oxidation of Plasma Cysteine/Cystine Redox State in Endotoxin-Induced Lung Injury

Several lines of evidence indicate that perturbations in the extracellular thiol/disulfide redox environment correlate with the progression and severity of acute lung injury (ALI). Cysteine (Cys) and its disulfide Cystine (CySS) constitute the most abundant, low-molecular-weight thiol/disulfide redox couple in the plasma, and Cys homeostasis is adversely affected during the inflammatory response to infection and injury. While much emphasis has been placed on glutathione (GSH) and glutathione disulfide (GSSG), little is known about the regulation of the Cys/CySS couple in ALI. The purpose of the present study was to determine whether endotoxin administration causes a decrease in Cys and/or an oxidation of the plasma Cys/CySS redox state (E(h) Cys/CySS), and to determine whether these changes were associated with changes in plasma E(h) GSH/GSSG. Mice received endotoxin intraperitoneally, and GSH and Cys redox states were measured at time points known to correlate with the progression of endotoxin-induced lung injury. E(h) in mV was calculated using Cys, CySS, GSH, and GSSG values by high-performance liquid chromatography and the Nernst equation. We observed distinct effects of endotoxin on the GSH and Cys redox systems during the acute phase; plasma E(h) Cys/CySS was selectively oxidized early in response to endotoxin, while E(h) GSH/GSSG remained unchanged. Unexpectedly, subsequent oxidation of E(h) GSH/GSSG and E(h) Cys/CySS occurred as a consequence of endotoxin-induced anorexia. Taken together, the results indicate that enhanced oxidation of Cys, altered transport of Cys and CySS, and decreased food intake each contribute to the oxidation of plasma Cys/CySS redox state in endotoxemia.

Hypertonic saline reduces inflammation and enhances the resolution of oleic acid induced acute lung injury

BackgroundHypertonic saline (HTS) reduces the severity of lung injury in ischemia-reperfusion, endotoxin-induced and ventilation-induced lung injury. However, the potential for HTS to modulate the resolution of lung injury is not known. We investigated the potential for hypertonic saline to modulate the evolution and resolution of oleic acid induced lung injury.MethodsAdult male Sprague Dawley rats were used in all experiments. Series 1 examined the potential for HTS to reduce the severity of evolving oleic acid (OA) induced acute lung injury. Following intravenous OA administration, animals were randomized to receive isotonic (Control, n = 12) or hypertonic saline (HTS, n = 12), and the extent of lung injury assessed after 6 hours. Series 2 examined the potential for HTS to enhance the resolution of oleic acid (OA) induced acute lung injury. Following intravenous OA administration, animals were randomized to receive isotonic (Control, n = 6) or hypertonic saline (HTS, n = 6), and the extent of lung injury assessed after 6 hours.ResultsIn Series I, HTS significantly reduced bronchoalveolar lavage (BAL) neutrophil count compared to Control [61.5 ± 9.08 versus 102.6 ± 11.89 × 103 cells.ml-1]. However, there were no between group differences with regard to: A-a O2 gradient [11.9 ± 0.5 vs. 12.0 ± 0.5 KPa]; arterial PO2; static lung compliance, or histologic injury. In contrast, in Series 2, hypertonic saline significantly reduced histologic injury and reduced BAL neutrophil count [24.5 ± 5.9 versus 46.8 ± 4.4 × 103 cells.ml-1], and interleukin-6 levels [681.9 ± 190.4 versus 1365.7 ± 246.8 pg.ml-1].ConclusionThese findings demonstrate, for the first time, the potential for HTS to reduce pulmonary inflammation and enhance the resolution of oleic acid induced lung injury.

Recombinant human activated protein C attenuates endotoxin-induced lung injury in awake sheep

IntroductionAcute lung injury often complicates severe sepsis. In Gram-negative sepsis, bacterial endotoxin activates both coagulation and inflammation. Enhanced lung vascular pressures and permeability, increased extravascular lung water content and deteriorated gas exchange characterize ovine endotoxin-induced lung injury, a frequently used model of acute lung injury. Recombinant human activated protein C (rhAPC), with its anticoagulant, anti-inflammatory, fibrinolytic and antiapoptotic effects, reportedly reduces the respirator-dependent days and the mortality of patients with severe sepsis. We speculate whether rhAPC antagonizes endotoxin-induced lung injury in sheep.MethodsTwo groups of sheep were exposed to Escherichia coli endotoxin (lipopolysaccharide) 15 ng/kg/minute intravenously from 0 to 24 hours; one group received only lipopolysaccharide throughout (n = 8), and the other group received lipopolysaccharide in combination with rhAPC 24 μg/kg/hour from 4 to 24 hours (n = 9). In addition, one group received rhAPC as above as the only intervention (n = 4), and four sham-operated sheep were used for determination of the α and ε isoforms of protein kinase C in pulmonary tissue. Data were assessed by one-way analysis of variance for repeated measurements. Biochemical data were analyzed using Student's t test, or using the Mann–Whitney U test when appropriate.ResultsInfusion of endotoxin caused lung injury, manifested by increments in pulmonary artery pressure, in pulmonary micro-occlusion pressure, in pulmonary vascular downstream resistance, in pulmonary vascular permeability index, in extravascular lung water index and in deterioration of oxygenation that were all attenuated by infusion of rhAPC. Endotoxemia led to changes in inflammation and coagulation, including pulmonary neutrophil accumulation paralleled by increased TNFα and decreased protein C and fibrinogen in animal plasma, which all improved following infusion of rhAPC. Moreover, rhAPC prevented the translocation of protein kinase C α and ε isoforms from the cytosolic fraction of lung tissue extracts.ConclusionIn awake sheep, rhAPC alleviates endotoxin-induced lung injury – as characterized by improvements of oxygenation, coagulation and inflammation, as well as by reversal of pulmonary hemodynamic and volumetric changes.

Association between inflammatory mediators and response to inhaled nitric oxide in a model of endotoxin-induced lung injury

IntroductionInhaled nitric oxide (INO) allows selective pulmonary vasodilation in acute respiratory distress syndrome and improves PaO2 by redistribution of pulmonary blood flow towards better ventilated parenchyma. One-third of patients are nonresponders to INO, however, and it is difficult to predict who will respond. The aim of the present study was to identify, within a panel of inflammatory mediators released during endotoxin-induced lung injury, specific mediators that are associated with a PaO2 response to INO.MethodsAfter animal ethics committee approval, pigs were anesthetized and exposed to 2 hours of endotoxin infusion. Levels of cytokines, prostanoid, leucotriene and endothelin-1 (ET-1) were sampled prior to endotoxin exposure and hourly thereafter. All animals were exposed to 40 ppm INO: 28 animals were exposed at either 4 hours or 6 hours and a subgroup of nine animals was exposed both at 4 hours and 6 hours after onset of endotoxin infusion.ResultsBased on the response to INO, the animals were retrospectively placed into a responder group (increase in PaO2 ≥ 20%) or a nonresponder group. All mediators increased with endotoxin infusion although no significant differences were seen between responders and nonresponders. There was a mean difference in ET-1, however, with lower levels in the nonresponder group than in the responder group, 0.1 pg/ml versus 3.0 pg/ml. Moreover, five animals in the group exposed twice to INO switched from responder to nonresponder and had decreased ET-1 levels (3.0 (2.5 to 7.5) pg/ml versus 0.1 (0.1 to 2.1) pg/ml, P < 0.05). The pulmonary artery pressure and ET-1 level were higher in future responders to INO.ConclusionsET-1 may therefore be involved in mediating the response to INO.

Role of platelet activating factor in pathogenesis of acute respiratory distress syndrome

Role of platelet activating factor in pathogenesis of acute respiratory distress syndrome

Prevention of endotoxin-induced systemic response by bone marrow-derived mesenchymal stem cells in mice

Bone marrow-derived mesenchymal stem cells (BMDMSCs) appear to be important in repair of the chronic lung injury caused by bleomycin in mice. To determine effects of these BMDMSCs on an acute inflammatory response, we injected C57BL/6 mice intraperitoneally with 1 mg/kg endotoxin followed either by intravenous infusion of 5 x 10(5) BMDMSCs, the same number of lung fibroblasts, or an equal volume of normal saline solution. Lungs harvested 6, 24, and 48 h and 14 days after endotoxin showed that BMDMSC administration prevented endotoxin-induced lung inflammation, injury, and edema. Although we were able to detect donor cells in the lungs at 1 day after endotoxin, by 14 days no donor cells were detected. BMDMSC administration suppressed the endotoxin-induced increase in circulating proinflammatory cytokines without decreasing circulating levels of anti-inflammatory mediators. Ex vivo cocultures of BMDMSC and lung cells from endotoxemic animals demonstrated a bilateral conversation in which lung cells stimulated proliferation and migration of stem cells and suppressed proinflammatory cytokine production by lung cells. We conclude that BMDMSCs decrease both the systemic and local inflammatory responses induced by endotoxin. These effects do not require either lung engraftment or differentiation of the stem cells and are due at least in part to the production of stem cell chemoattractants by the lungs and to humoral and physical interactions between stem cells and lung cells. We speculate that mobilization of this population of BMDMSCs may be a general mechanism for modulating an acute inflammatory response.

The Immunomodulatory Effect of Sevoflurane in Endotoxin-Injured Alveolar Epithelial Cells

Endotoxin-induced lung injury is a useful experimental system for the characterization of immunopathologic mechanisms in acute lung injury. Although alveolar epithelial cells (AEC) are directly exposed to volatile anesthetics, there is limited information about the effect of anesthetics on these cells. In this study we investigated the effect of pretreatment with the inhaled anesthetic sevoflurane on lipopolysaccharide (LPS)-injured AEC. AEC were incubated with 1.1 vol % sevoflurane for 0.5 h, followed by LPS stimulation for 5 h. Expression of monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1beta (MIP-1beta), macrophage inflammatory protein-2 (MIP-2), cytokine-induced neutrophil chemoattractant-1 (CINC-1), and intercellular adhesion molecule-1 (ICAM-1) was analyzed. In addition, functional tests were performed through chemotaxis and adherence assays to underline the biological relevance of the findings. Exposure of AEC to sevoflurane resulted in a 50% downregulation of MCP-1 protein in the sevoflurane-LPS group when compared with non-sevoflurane- LPS cells (P < 0.05). MIP-1beta concentration in LPS-stimulated cells decreased by 32% with sevoflurane (P < 0.05), MIP-2 by 29% (P < 0.05), and CINC-1 by 20% (P < 0.05). ICAM-1 protein expression was attenuated by 36% (P < 0.05). This inhibition caused substantial changes in the inflammatory response of neutrophils. 33% less chemotactic activity was seen in sevoflurane-treated LPS cells (P < 0.001) as well as 47% decreased adhesion of neutrophils to AEC (P < 0.001). This study shows that sevoflurane alters the LPS-induced inflammatory response, not only with respect to the expression pattern of inflammatory mediators, but also regarding the biological consequences with less accumulation of effector cells such as neutrophils.

MLCK210 gene knockout or kinase inhibition preserves lung function following endotoxin-induced lung injury in mice

Barrier dysfunction, involving the endothelium or epithelium, is implicated in the pathophysiology of many disease states, including acute and ventilator-associated lung injury. Evidence from cell culture, in vivo and clinical studies, has identified myosin light chain kinase as a drug discovery target for such diseases. Here, we measured disease-relevant end points to test the hypothesis that inhibition of myosin light chain kinase is a potential therapeutic target for treatment of barrier dysfunction resulting from acute lung injury. We used a combined gene knockout and chemical biology approach with an in vivo intact lung injury model. We showed that inhibition of myosin light chain kinase protects lung function, preserves oxygenation, prevents acidosis, and enhances survival after endotoxin exposure with subsequent mechanical ventilation. This protective effect provided by the small molecule inhibitor of myosin light chain kinase is present when the inhibitor is administered during a clinically relevant injury paradigm after endotoxin exposure. Treatment with inhibitor confers additional protection against acute lung injury to that provided by a standard protective mode of ventilation. These results support the hypothesis that myosin light chain kinase is a potential therapeutic target for acute lung injury and provide clinical end points of arterial blood gases and pulmonary compliance that facilitate the direct extrapolation of these studies to measures used in critical care medicine.

Protective Effects of Isoflurane Pretreatment in Endotoxin-induced Lung Injury

Protective Effects of Isoflurane Pretreatment in Endotoxin-induced Lung Injury

Ropivacaine Decreases Inflammation in Experimental Endotoxin induced Lung Injury

Ropivacaine Decreases Inflammation in Experimental Endotoxin induced Lung Injury

Influence of Fructose-1,6-Diphosphate on Endotoxin-Induced Lung Injuries in Sheep

Fructose-1,6-diphosphate (FDP) is reported to have a salutary effect in endotoxin shock and sepsis. This investigation describes the effect of FDP on pulmonary and systemic hemodynamics, lung lymph protein clearance, and leukocyte count in sheep infused with Escherichia coli endotoxin. Anesthetized sheep (n = 18), some of which underwent thoracotomy to cannulate lymphatic nodes, were used in this study. After stabilization, all sheep received E. coli endotoxin, 5 microg/kg i.v. infusion over 30 min. Concomitant with the endotoxin infusion, half of the animals were randomly selected to receive an i.v. bolus of FDP (10%), 50 mg/kg, followed by a continuous infusion of 5 mg.kg(-1).min(-1) for 4 h; the rest were treated in the same manner with glucose (10%) in 0.9% NaCl. Pulmonary artery pressure (PAP) and resistance in the glucose group increased from 20.8 +/- 1.6 to 36.7 +/- 3.2 mmHg (P < 0.007) and from 531 +/- 114 to 1137 +/- 80 dyn.s(-1).cm(-5), respectively (P < 0.005). Despite an increase during endotoxin infusion, these parameters in the FDP group returned to control values. There were no differences in left ventricular pressures, cardiac output, heart rate, and arterial oxygen tension between the groups. In the glucose group, lymph protein clearance was higher (P < 0.01) and blood leukocyte count was lower (P < 0.02). The wet/dry lung weight ratio (g/g) for the glucose group was 5.57 +/- 0.04 and for the FDP-treated group 4.76 +/- 0.06 (P < 0.0005). FDP treatment attenuated significantly the characteristic pulmonary hypertension, lung lymph protein clearance, and pulmonary vascular leakage seen in sheep infused with endotoxin.

Role of a Reduction of Cytokine Levels in Isoflurane-mediated Protection from Endotoxin-induced Lung Injury

Institute of Child Health, University of Liverpool, Liverpool, United Kingdom. michael_eisenhut@yahoo.comReutershan et al. 1reported on the finding of reduced endotoxin-induced acute lung injury in mice pretreated with isoflurane. In their investigation of the underlying cause of this phenomenon, the authors focused on neutrophil recruitment and chemokine concentrations. They found a reduction of neutrophil recruitment and CXCL1 and CXCL2/3 chemokine concentrations in the lungs of isoflurane-treated mice. Previous studies have not established a causal link between chemokine levels or the associated neutrophil accumulation and endotoxin-induced lung injury. There is, however, evidence that the cytokines tumor necrosis factor and interleukin 1 are involved in a reduction of alveolar ion and the associated fluid transport and hence pulmonary edema clearance.2,3Particularly tumor necrosis factor has been strongly implicated in the pathogenesis of pulmonary edema, and its effect is mediated by nitric oxide.2,4Tumor necrosis factor–induced nitric oxide leads thereby to a reduction of the activity of the alveolar epithelial sodium channel and the basolateral sodium potassium adenosine triphosphatase, which are essential for alveolar sodium and fluid transport.2Isoflurane has been shown to reduce plasma interleukin 1β and tumor necrosis factor levels significantly in endotoxemic rats.5The underlying cause for this effect has been investigated and found to be an inhibition of nuclear transcription factor KB.6The reduction in chemokine levels and subsequently neutrophil accumulation may be only a reflection of this inhibition of nuclear transcription factor KB rather than causally related to lung injury reduction, because chemokine genes are part of the array of genes regulated by this transcriptional factor.7Future studies on the protective effect of isoflurane against lung injury must correlate its effect on tumor necrosis factor and interleukin-1 levels with measures of pulmonary edema clearance.Institute of Child Health, University of Liverpool, Liverpool, United Kingdom. michael_eisenhut@yahoo.com

Role of a Reduction of Cytokine Levels in Isoflurane-mediated Protection from Endotoxin-induced Lung Injury

Role of a Reduction of Cytokine Levels in Isoflurane-mediated Protection from Endotoxin-induced Lung Injury

Mechanical ventilation affects alveolar fibrinolysis in LPS-induced lung injury

The aim of the present study was to determine the effects of mechanical ventilation on alveolar fibrin turnover in lipopolysaccharide (LPS)-induced lung injury. In a randomised controlled trial, Sprague-Dawley rats (n = 61) were allocated to three ventilation groups after intratracheal LPS (Salmonella enteritidis) instillations. Group I animals were subjected to 16 cmH(2)O positive inspiratory pressure (PIP) and 5 cmH(2)O positive end-expiratory pressure (PEEP); group II animals to 26 cmH(2)O PIP and 5 cmH(2)O PEEP; and group III animals to 35 cmH(2)O PIP and 5 cmH(2)O PEEP. Control rats (not mechanically ventilated) received LPS. Healthy rats served as a reference group. Levels of thrombin-antithrombin complex (TATc), D-dimer, plasminogen activator inhibitor (PAI) activity and PAI-1 antigen in bronchoalveolar lavage fluid were measured. LPS-induced lung injury increased TATc, D-dimer and PAI activity and PAI-1 antigen levels versus healthy animals. High pressure-amplitude ventilation increased TATc concentrations. D-dimer concentrations were not significantly raised. Instead, PAI activity increased with the amplitude of the pressure, from 0.7 U.mL(-1) in group I to 3.4 U.mL(-1) in group II and 5.0 U.mL(-1) in group III. There was no change in PAI-1 antigen levels. In conclusion, mechanical ventilation creates an alveolar/pulmonary anti-fibrinolytic milieu in endotoxin-induced lung injury which, at least in part, might be due to an increase in plasminogen activator inhibitor activity.