Alveolar-capillary Permeability Research Articles

Evaluation of the pulmonary effects of short-term nose-only cigarette smoke exposure in mice

Much is known about the chronic effects of cigarette smoke (CS) on lung function and inflammation and development of chronic obstructive pulmonary disease. However, the underlying pathophysiological mechanisms related to the short-term exposure to CS are not fully understood. Here, we assessed the effect of CS generated by nine consecutive cigarettes per day for four days in a nose-only exposure system on airway resistance measured using forced oscillation technique, lung inflammation and oxidative stress in BALB/c mice. Control mice were exposed to air. Mice exposed to CS showed a significant increase of neutrophils and lymphocytes numbers in bronchoalveolar lavage (BAL). The total protein and endothelin levels in BAL fluid were significantly augmented suggesting an increase of alveolar-capillary barrier permeability. Similarly, airway resistance was significantly increased in the CS group compared with controls. Furthermore, reactive oxygen species and lipid peroxidation levels in lung tissue were significantly increased. The antioxidant activities of reduced glutathione, glutathione S transferase and superoxide dismutase were all significantly increased following CS exposure, indicating that CS could trigger adaptive responses that counterbalance the potentially damaging activity of oxygen radicals induced by CS exposure. In conclusion, our data indicate that short-term nose-only exposure to CS causes lung inflammation and increase of airway resistance mediated at least partly through the oxidative stress.

The severity of shock is associated with impaired rates of net alveolar fluid clearance in clinical acute lung injury

The rate of alveolar fluid clearance (AFC) is associated with mortality in clinical acute lung injury (ALI). Patients with ALI often develop circulatory shock, but how shock affects the rate of AFC is unknown. To determine the effect of circulatory shock on the rate of AFC in patients with ALI, the rate of net AFC was measured in 116 patients with ALI by serial sampling of pulmonary edema fluid. The primary outcome was the rate of AFC in patients with shock compared with those without shock. We also tested the effects of shock severity and bacteremia. Patients with ALI and shock (n = 86) had significantly slower rates of net AFC compared with those without shock (n = 30, P = 0.03), and AFC decreased significantly as the number of vasopressors increased. Patients with positive blood cultures (n = 21) had slower AFC compared with patients with negative blood cultures (n = 96, P = 0.023). In addition, the edema fluid-to-plasma protein ratio, an index of alveolar-capillary barrier permeability, was highest in patients requiring the most vasopressors (P < 0.05). Patients with ALI complicated by circulatory shock and bacteremia had slower rates of AFC compared with patients without shock or bacteremia. An impaired capacity to reabsorb alveolar edema fluid may contribute to high mortality among patients with sepsis-induced ALI. These findings also suggest that vasopressor use may be a marker of alveolar-capillary barrier permeability in ALI and provide justification for new therapies that enhance alveolar epithelial and endothelial barrier integrity in ALI, particularly in patients with shock.

WNT1-Inducible Signaling Pathway Protein 1 Contributes to Ventilator-Induced Lung Injury

Although strides have been made to reduce ventilator-induced lung injury (VILI), critically ill patients can vary in sensitivity to VILI, suggesting gene-environment interactions could contribute to individual susceptibility. This study sought to uncover candidate genes associated with VILI using a genome-wide approach followed by functional analysis of the leading candidate in mice. Alveolar-capillary permeability after high tidal volume (HTV) ventilation was measured in 23 mouse strains, and haplotype association mapping was performed. A locus was identified on chromosome 15 that contained ArfGAP with SH3 domain, ankyrin repeat and PH domain 1 (Asap1), adenylate cyclase 8 (Adcy8), WNT1-inducible signaling pathway protein 1 (Wisp1), and N-myc downstream regulated 1 (Ndrg1). Information from published studies guided initial assessment to Wisp1. After HTV, lung WISP1 protein increased in sensitive A/J mice, but was unchanged in resistant CBA/J mice. Anti-WISP1 antibody decreased HTV-induced alveolar-capillary permeability in sensitive A/J mice, and recombinant WISP1 protein increased HTV-induced alveolar-capillary permeability in resistant CBA/J mice. HTV-induced WISP1 coimmunoprecipitated with glycosylated Toll-like receptor (TLR) 4 in A/J lung homogenates. After HTV, WISP1 increased in strain-matched control lungs, but was unchanged in TLR4 gene-targeted lungs. In peritoneal macrophages from strain-matched mice, WISP1 augmented LPS-induced TNF release that was inhibited in macrophages from TLR4 or CD14 antigen gene-targeted mice, and was attenuated in macrophages from myeloid differentiation primary response gene 88 gene-targeted or TLR adaptor molecule 1 mutant mice. These findings support a role for WISP1 as an endogenous signal that acts through TLR4 signaling to increase alveolar-capillary permeability in VILI.

Mast cells mediate Pseudomonas aeruginosa lipopolysaccharide-induced lung inflammation in rat

Activated mast cells have been demonstrated to play a pivotal role in Pseudomonas aeruginosa lung infections. However, there is no report about the involvement of mast cells in P. aeruginosa lipopolysaccharide (LPS)-induced lung inflammation. This study aimed at evaluating the role of mast cells in P. aeruginosa LPS-induced lung inflammation in rats. Mast cells stabilization was carried out by intraperitoneal injections of cromolyn. Lung inflammation was induced by the intratracheal instillation of P. aeruginosa LPS (5 μg/kg bw) and inflammatory status was evaluated 4 h post-LPS instillation. We found that activated mast cells could constitute a pivotal source of several inflammatory cytokines, including TNF-α, IL-1β, and IL-6. These cells might regulate polymorphonuclear neutrophil (PMN) recruitment and be implicated in the alteration of alveolar-capillary permeability via the release of TNF-α and IL-1β. We also detected that activated mast cells could be involved in the alteration of the expression of two epithelial tight junction proteins (claudin-1 and occludin) during the acute phase of inflammation. Our results suggest that activated mast cells might play a critical role in P. aeruginosa LPS-induced lung inflammation. Therefore, mast cell stabilization may be a potential novel approach for the prevention and treatment of P. aeruginosa-induced lung infections.

Metformin attenuates ventilator-induced lung injury.

IntroductionDiabetic patients may develop acute lung injury less often than non-diabetics; a fact that could be partially ascribed to the usage of antidiabetic drugs, including metformin. Metformin exhibits pleiotropic properties which make it potentially beneficial against lung injury. We hypothesized that pretreatment with metformin preserves alveolar capillary permeability and, thus, prevents ventilator-induced lung injury.MethodsTwenty-four rabbits were randomly assigned to pretreatment with metformin (250 mg/Kg body weight/day per os) or no medication for two days. Explanted lungs were perfused at constant flow rate (300 mL/min) and ventilated with injurious (peak airway pressure 23 cmH2O, tidal volume ≈17 mL/Kg) or protective (peak airway pressure 11 cmH2O, tidal volume ≈7 mL/Kg) settings for 1 hour. Alveolar capillary permeability was assessed by ultrafiltration coefficient, total protein concentration in bronchoalveolar lavage fluid (BALF) and angiotensin-converting enzyme (ACE) activity in BALF.ResultsHigh-pressure ventilation of the ex-vivo lung preparation resulted in increased microvascular permeability, edema formation and microhemorrhage compared to protective ventilation. Compared to no medication, pretreatment with metformin was associated with a 2.9-fold reduction in ultrafiltration coefficient, a 2.5-fold reduction in pulmonary edema formation, lower protein concentration in BALF, lower ACE activity in BALF, and fewer histological lesions upon challenge of the lung preparation with injurious ventilation. In contrast, no differences regarding pulmonary artery pressure and BALF total cell number were noted. Administration of metformin did not impact on outcomes of lungs subjected to protective ventilation.ConclusionsPretreatment with metformin preserves alveolar capillary permeability and, thus, decreases the severity of ventilator-induced lung injury in this model.

Pulmonary vascular permeability index should not be called extravascular lung water pulmonary blood volume ratio

In their recent paper, Michelle Chew and colleagues [1] evaluated the performance accuracy of three extra vascular lung water (EVLW) ratios in patients with shock at risk for or with acute lung injury (ALI). Th ey indexed EVLW to actual body weight (ABW), predicted body weight (PBW) and pulmonary blood volume (PBV), and confi rmed that all EVLW ratios were higher in patients with ALI and in non-survivors and correlated with respiratory parameters. Although these fi ndings are interesting, they deserve some comments. First, whereas indexing EVLW to PBW may reduce the number of patients with acute respiratory distress syndrome (ARDS) with normal EVLW, in this population, the EVLW/ABW index performed best [2]. Furthermore, the absence of a link between EVLW and PaO 2 /FiO 2 (calculated r2 of 0.14 to 0.23) could explain that these indices identifi ed only 33% of ALI and 38% of ARDS cases. Second, the EVLW/PBV terminology appears very unusual. Th e transpulmonary thermodilution technique determines cardiac output, intrathoracic thermal volume (ITTV), pulmonary thermal volume (PTV) and global end-diastolic volume (Global end-diastolic volume (GEDV) = ITTV - PTV). Th e estimated blood volume of the chest (Intra thoracic blood volume (ITBV) = GEDV + PBV) permits the calculation of PBV (ITBV = 1.25 × GEDV - 28.4 ml) [3]. Importantly, the PiCCO monitor automatically provides, at each calibration, an estimation of the pulmonary vascular permeability index (PVPI), based on the ratio of EVLW to PBV, which refl ects alveolar-capillary barrier permeability and is of importance for the mechanisms of pulmonary edema [4,5]. Th us, I believe that it would be more pertinent to use the PVPI instead of the EVLW/PBV ratio and that it is time to promote an international consensus on this. Abbreviations ABW, actual body weight; ALI, acute lung injury; ARDS, acute respiratory distress syndrome; EVLW, extravascular lung water; GEDV, global end-diastolic volume; ITBV, intrathoracic blood volume; ITTV, intrathoracic thermal volume; PBV, pulmonary blood volume; PBW, predicted body weight; PVPI, pulmonary vascular permeability index. Competing interests The author declares that they have no competing interests.

S73 Macrophages as vehicles for delivering cell therapy to injured lung

IntroductionInjury to the alveolar epithelium underlies a number of important lung diseases, exemplified by the syndromes of acute lung injury and acute respiratory distress syndrome, which currently have a poor...

Modulation of Pseudomonas aeruginosa lipopolysaccharide-induced lung inflammation by chronic iron overload in rat

Iron constitutes a critical nutrient source for bacterial growth, so iron overload is a risk factor for bacterial infections. This study aimed at investigating the role of iron overload in modulating bacterial endotoxin-induced lung inflammation. Weaning male Wistar rats were intraperitoneally injected with saline or iron sucrose [15 mg kg(-1) body weight (bw), 3 times per week, 4 weeks]. They were then intratracheally injected with Pseudomonas aeruginosa lipopolysaccharide (LPS) (5 μg kg(-1) bw) or saline. Inflammatory indices were evaluated 4 or 18 h post-LPS/saline injection. At 4 h, LPS-treated groups revealed significant increases in the majority of inflammatory parameters (LPS-binding protein (LBP), immune cell recruitment, inflammatory cytokine synthesis, myeloperoxidase activity, and alteration of alveolar-capillary permeability), as compared with control groups. At 18 h, these parameters reduced strongly with the exception for LBP content and interleukin (IL)-10. In parallel, iron acted as a modulator of immune cell recruitment; LBP, tumor necrosis factor-α, cytokine-induced neutrophil chemoattractant 3, and IL-10 synthesis; and alveolar-capillary permeability. Therefore, P. aeruginosa LPS may only act as an acute lung inflammatory molecule, and iron overload may modulate lung inflammation by enhancing different inflammatory parameters. Thus, therapy for iron overload may be a novel and efficacious approach for the prevention and treatment of bacterial lung inflammations.

Lung-specific loss of the laminin α3 subunit confers resistance to mechanical injury

Laminins are heterotrimeric glycoproteins of the extracellular matrix that are secreted by epithelial cells and which are crucial for the normal structure and function of the basement membrane. We have generated a mouse harboring a conditional knockout of α3 laminin (Lama3(fl/fl)), one of the main laminin subunits in the lung basement membrane. At 60 days after intratracheal treatment of adult Lama3(fl/fl) mice with an adenovirus encoding Cre recombinase (Ad-Cre), the protein abundance of α3 laminin in whole lung homogenates was more than 50% lower than that in control-treated mice, suggesting a relatively long half-life for the protein in the lung. Upon exposure to an injurious ventilation strategy (tidal volume of 35 ml per kg of body weight for 2 hours), the mice with a knockdown of the α3 laminin subunit had less severe injury, as shown by lung mechanics, histology, alveolar capillary permeability and survival when compared with Ad-Null-treated mice. Knockdown of the α3 laminin subunit resulted in evidence of lung inflammation. However, this did not account for their resistance to mechanical ventilation. Rather, the loss of α3 laminin was associated with a significant increase in the collagen content of the lungs. We conclude that the loss of α3 laminin in the alveolar epithelium results in an increase in lung collagen, which confers resistance to mechanical injury.

Lung-specific loss of the laminin α3 subunit confers resistance to mechanical injury

Laminins are heterotrimeric glycoproteins of the extracellular matrix that are secreted by epithelial cells and which are crucial for the normal structure and function of the basement membrane. We have generated a mouse harboring a conditional knockout of α3 laminin (Lama3fl/fl), one of the main laminin subunits in the lung basement membrane. At 60 days after intratracheal treatment of adult Lama3fl/fl mice with an adenovirus encoding Cre recombinase (Ad-Cre), the protein abundance of α3 laminin in whole lung homogenates was more than 50% lower than that in control-treated mice, suggesting a relatively long half-life for the protein in the lung. Upon exposure to an injurious ventilation strategy (tidal volume of 35 ml per kg of body weight for 2 hours), the mice with a knockdown of the α3 laminin subunit had less severe injury, as shown by lung mechanics, histology, alveolar capillary permeability and survival when compared with Ad-Null-treated mice. Knockdown of the α3 laminin subunit resulted in evidence of lung inflammation. However, this did not account for their resistance to mechanical ventilation. Rather, the loss of α3 laminin was associated with a significant increase in the collagen content of the lungs. We conclude that the loss of α3 laminin in the alveolar epithelium results in an increase in lung collagen, which confers resistance to mechanical injury.

Biomarkers of Oxidative Stress Study IV: Ozone exposure of rats and its effect on antioxidants in plasma and bronchoalveolar lavage fluid

The objective of this study was to determine whether acutely exposing rats to ozone would result in the loss of antioxidants from plasma and bronchoalveolar lavage fluid (BALF). Additional goals were to compare analyses of the same antioxidant concentration between different laboratories, to investigate which methods have the sensitivity to detect decreased levels of antioxidants, and to identify a reliable measure of oxidative stress in ozone-exposed rats. Male Fisher rats were exposed to either 2.0 or 5.0ppm ozone inhalation for 2h. Blood plasma and BALF samples were collected 2, 7, and 16h after the exposure. It was found that ascorbic acid in plasma collected from rats after the higher dose of ozone was lower at 2h, but not later. BALF concentrations of ascorbic acid were decreased at both 2 and 7h postexposure. Tocopherols (α, δ, γ), 5-nitro-γ-tocopherol, tocol, glutathione (GSH/GSSG), and cysteine (Cys/CySS) were not decreased, regardless of the dose or postexposure time point used for sample collection. Uric acid was significantly increased by the low dose at 2h and the high dose at the 7h point, probably because of the accumulation of blood plasma in the lung from ozone-increased alveolar capillary permeability. We conclude that measurements of antioxidants in plasma are not sensitive biomarkers for oxidative damage induced by ozone and are not a useful choice for the assessment of oxidative damage by ozone in vivo.

Differences in acute lung response to elastase instillation in two rodent species may determine differences in severity of emphysema development

Elastase intratracheal instillation induces early emphysema in rodents. However, Syrian Golden hamsters develop more severe emphysema than Sprague-Dawley rats. We have reported species differences in oxidant/antioxidant balance modulating antiprotease function early after instillation. We now hypothesize that other components of the initial lung response to elastase might also be species-dependent. Sprague-Dawley rats and Syrian Golden hamsters received a single dose of pancreatic elastase (0.55 U/100 g body wt) to study acute lung injury biomarkers. Using serum, lung, and bronchoalveolar lavage fluid (BALF) samples, we evaluated changes in alveolar-capillary permeability, alpha 1-antitrypsin (α(1)-AT) concentration and activity, glutathione content, and proinflammatory cytokines. Rats showed a large increase in alveolar-capillary permeability and few hemorrhagic changes, whereas hamsters exhibited large hemorrhagic changes (P < 0.01) and mild transendothelial passage of proteins. Western blots showed a 30-fold increase in BALF α(1)-AT concentration in rats and only a 7-fold increase in hamsters (P < 0.001), with [α(1)-AT-elastase] complexes only in rats, suggesting differences in antiprotease function. This was confirmed by the α(1)-AT bioassay showing 20-fold increase in α(1)-AT activity in rats and only twofold increase in hamsters (P < 0.001). In rats, results were preceded by a 3-, 60-, and 20-fold increase in IL-6, IL-1β, and TNF-α respectively (P < 0.001). In hamsters, only IL-1β and TNF-α showed mild increases. All parameters studied were back to baseline by 4 days. In conclusion, several components of the initial lung response showed species differences. Cytokine release pattern and functional inhibition of α(1)-AT were the most significant components differing among species and could account for differences in susceptibility to elastase.

NUCLEAR EVALUATION OF ALVEOLAR CAPILLARY PERMEABILITY FOR DIFFERENTIAL DIAGNOSIS OF PULMONARY INFILTRATES

Summary. Ventilation scintigraphy of the lungs with analysis of alveolar-capillary permeability (ACP) was performed in patients with confirmed diagnoses of community-acquired pneumonia (CAP, n = 40), infiltrative pulmonary tuberculosis (IPT, n = 20), distal pulmonary embolism (DPE, n = 11),peripheral lung carcinoma (PLC, n = 17), and in 22 healthy volunteers. ACP values were higher in affected and intact lungs in patients with CAP at 10 and 30 min of the investigation vs those with DPE and were higher at 30 min in the affected lung in patients with CAP compared to patients with IPT. Comparison of ACPs in DPE and IPT patients revealed the ACP reduction in affected and intact lungs of DPE patients at 30 min of the investigation. PLC patients demonstrated the ACP reduction in affected lung compared to contralateral lung. Therefore, ACP gave additional information for differential diagnosis of CAP, IPT, DPE and PLC

Ascorbate and Deferoxamine Administration after Chlorine Exposure Decrease Mortality and Lung Injury in Mice

Chlorine (Cl(2)) gas exposure poses an environmental and occupational hazard that frequently results in acute lung injury. There is no effective treatment. We assessed the efficacy of antioxidants, administered after exposure, in decreasing mortality and lung injury in C57BL/6 mice exposed to 600 ppm of Cl(2) for 45 minutes and returned to room air. Ascorbate and deferoxamine were administered intramuscularly every 12 hours and by nose-only inhalation every 24 hours for 3 days starting after 1 hour after exposure. Control mice were exposed to Cl(2) and treated with vehicle (saline or water). Mortality was reduced fourfold in the treatment group compared with the control group (22 versus 78%; P = 0.007). Surviving animals in the treatment group had significantly lower protein concentrations, cell counts, and epithelial cells in their bronchoalveolar lavage (BAL). Lung tissue ascorbate correlated inversely with BAL protein as well as with the number of neutrophils and epithelial cells. In addition, lipid peroxidation was reduced threefold in the BAL of mice treated with ascorbate and deferoxamine when compared with the control group. Administration of ascorbate and deferoxamine reduces mortality and decreases lung injury through reduction of alveolar-capillary permeability, inflammation, and epithelial sloughing and lipid peroxidation.

P252 A physiological characterisation of injury, inflammation and resolution in murine aspiration pneumonitis

Introduction and ObjectivesAspiration pneumonitis is an important risk factor for acute lung injury/acute respiratory distress syndrome (ALI/ARDS).1 Animals models of ALI should ideally mimic the human situation, although to date...

Toll-like Receptor 4-Myeloid Differentiation Factor 88 Signaling Contributes to Ventilator-induced Lung Injury in Mice

The mechanisms of ventilator-induced lung injury, an iatrogenic inflammatory condition induced by mechanical ventilation, are not completely understood. Toll-like receptor 4 (TLR4) signaling via the adaptor protein myeloid differentiation factor 88 (MyD88) is proinflammatory and plays a critical role in host immune response to invading pathogen and noninfectious tissue injury. The role of TLR4-MyD88 signaling in ventilator-induced lung injury remains incompletely understood. Mice were ventilated with low or high tidal volume (HTV), 7 or 20 ml/kg, after tracheotomy for 4 h. Control mice were tracheotomized without ventilation. Lung injury was assessed by: alveolar capillary permeability to Evans blue albumin, wet/dry ratio, bronchoalveolar lavage analysis for cell counts, total proteins and cytokines, results of histopathological examination of the lung, and plasma cytokine levels. Wild-type mice subjected to HTV had increased pulmonary permeability, inflammatory cell infiltration/lung edema, and interleukin-6/macrophage-inflammatory protein-2 in the lavage compared with control mice. In HTV, levels of inhibitor of kappaB alpha decreased, whereas phosphorylated extracellular signal-regulated kinases increased. TLR4 mutant and MyD88 mice showed markedly attenuated response to HTV, including less lung inflammation, pulmonary edema, cell number, protein content, and the cytokines in the lavage. Furthermore, compared with wild-type mice, both TLR4 mutant and MyD88 mice had significantly higher levels of inhibitor of kappaB alpha and reduced extracellular signal-regulated kinase phosphorylation after HTV. TLR4-MyD88 signaling plays an important role in the development of ventilator-induced lung injury in mice, possibly through mechanisms involving nuclear factor-kappaB and mitogen-activated protein kinase pathways.

Propofol Prevents Lung Injury Following Intestinal Ischemia-Reperfusion

The antioxidant properties of propofol have been shown to improve ischemia/reperfusion injury. We investigated whether anesthesia with propofol can ameliorate remote lung injury induced by intestinal ischemia-reperfusion (IIR). Thirty male Wistar rats were randomly allocated in three groups (n = 10 each): animals in group Sham were anesthetized with ketamine and xylazine and then laparotomy and sham IIR followed. Animals in group IIR received ketamine and xylazine and were then subjected to clamping of the superior mesenteric artery for 45 min and reperfusion for 4 h. Group IIR+P received anesthesia with propofol and then IIR was induced, as in group IIR. Blood samples for blood gases and malondialdehyde measurements were drawn at the end of reperfusion. Bronchoalveolar lavage fluid (BALF) was obtained to measure cell counts, total protein, and phospholipids levels. Induction of IIR resulted in deteriorated oxygenation, acidemia, and inflammatory cells sequestration, along with increased BALF protein content and increased proportions of small surfactant aggregates. Anesthesia with propofol alleviated intestinal injury and efficiently prevented lipid oxidation. In group IIR+P inflammatory cell infiltration and pulmonary histologic changes were significantly limited. The increase in BALF total protein and the changes in surfactant aggregates were prevented, leading to normal systemic oxygenation. Using propofol to induce and maintain anesthesia efficiently prevented IIR-induced lung injury. Systemic antioxidant protection, improvement of intestinal injury, inhibition of the inflammatory response, and preservation of the alveolar-capillary permeability seem to be crucial mediating mechanisms for this simple and clinically relevant intervention.

A label-free differential proteomic analysis of mouse bronchoalveolar lavage fluid exposed to ultrafine carbon black

Ultrafine carbon black (ufCB) is a potential hazard to the lung. It causes changes in protein expression and it increases alveolar–capillary permeability in the lung. Label-free quantitative proteomic methods allow a sensitive and accurate analytical method for identifying and quantifying proteins in a protein mixture without chemically modifying the proteins. We used a label-free quantitative proteomic approach that combined and aligned LC–MS and LC–MS/MS spectra to analyze mouse bronchoalveolar lavage fluid (BALF) protein changes associated with exposure to ufCB. We developed a simple normalization method for quantification without spiking the internal standard. The intensities of unchanged peptides were used as normalization factors based on a statistical method to avoid the influence of peptides changed because of ufCB. LC–MS/MS spectra and then database searching were used to identify proteins. The relative abundances of the aligned peptides of identified proteins were determined using LC–MS spectra. We identified 132 proteins, of which 77 are reported for the first time. In addition, the expression of 15 inflammatory proteins and surfactant-associated proteins was regulated (i.e., 7 upregulated and 8 downregulated) compared with the controls. Several proteins not previously reported provide complementary information on the proteins present in mouse BALF, and they are potential biomarkers for the understanding of mechanisms involved in ufCB-induced lung disorders hypothesize that using the label-free quantitative proteomic approach introduced here is well suited for more rigorous, large-scale quantitative analysis of biological samples. We hypothesize that this label-free quantitative proteomic approach will be suited for a large-scale quantitative analysis of biological samples.

Pretreatment with atorvastatin attenuates lung injury caused by high-stretch mechanical ventilation in an isolated rabbit lung model

We hypothesized that pretreatment with atorvastatin improves alveolar capillary permeability and hemodynamics and, thus, confers protection against lung injury caused by high-stretch mechanical ventilation. Twenty-four isolated sets of normal rabbit lungs were utilized. Treated animals received atorvastatin (20 mg/kg body weight/day by mouth) for 3 days before surgery. Lungs were perfused constantly (300 mL/min) and ventilated for 1 hr with pressure-control ventilation at either 23 (high pressure; resulting in tidal volume approximately 22 mL/kg) or 11 (low pressure; tidal volume approximately 10 mL/kg) cm H2O peak inspiratory pressure and positive end-expiratory pressure of 3 cm H2O. Four groups were examined: high pressure-no statin, high pressure-statin pretreatment, low pressure-no statin, and low pressure-statin pretreatment. The high-pressure-no statin group sustained more damage than the low-pressure groups. In high-pressure groups, lungs of statin-pretreated vs. no statin-pretreated animals sustained a significantly lower increase in ultrafiltration coefficient (an accurate marker of alveolar capillary permeability; high-pressure-statin pretreatment vs. high-pressure-no statin, -0.013 +/- 0.017 g/min/mm Hg/100g vs. 1.723 +/- 0.495 g/min/mm Hg/100g; p < .001), lower weight gain (i.e., less edema formation; 4.62 +/- 1.50 grams vs. 17.75 +/- 4.71 grams; p = .005), improved hemodynamics (i.e., lower increase in mean pulmonary artery pressure; 0.56 +/- 0.51 mm Hg vs. 5.62 +/- 1.52 mm Hg; p = .04), lower protein concentration in bronchoalveolar lavage fluid (p < .001), and fewer histologic lesions (p = .013). Apoptosis of lung parenchyma cells was not different (p = .97). There was no difference between low-pressure-statin pretreatment and low-pressure-no statin groups regarding these outcomes. In this model, atorvastatin improves alveolar capillary permeability and hemodynamics and, thus, attenuates lung injury caused by high-stretch mechanical ventilation.

Novel Role for Aldose Reductase in Mediating Acute Inflammatory Responses in the Lung

Exaggerated inflammatory responses and the resultant increases in alveolar-capillary permeability underlie the pathogenesis of acute lung injury during sepsis. This study examined the functions of aldose reductase (AR) in mediating acute lung inflammation. Transgenic mice expressing human AR (ARTg) were used to study the functions of AR since mice have low intrinsic AR activity. In a mild cecal ligation and puncture model, ARTg mice demonstrated an enhanced AR activity and a greater inflammatory response as evaluated by circulating cytokine levels, neutrophil accumulation in the lungs, and activation of Rho kinase in lung endothelial cells (ECs). Compared with WT lung cells, ARTg lung cells produced more IL-6 and showed augmented JNK activation in response to LPS stimulation ex vivo. In human neutrophils, AR activity was required for fMLP-included CD11b activation and up-regulation, respiratory burst, and shape changes. In human pulmonary microvascular ECs, AR activity was required for TNF-alpha-induced activation of the Rho kinase/MKK4/JNK pathway and IL-6 production, but not p38 activation or ICAM-1 expression. Importantly, AR activity in both human neutrophils and ECs was required for neutrophil adhesion to TNF-alpha-stimulated ECs. These data demonstrate a novel role for AR in regulating the signaling pathways leading to neutrophil-EC adhesion during acute lung inflammation.