Synthetic smoke with acrolein but not HCl produces pulmonary edema

The chemical toxins in smoke and not the heat are responsible for the pulmonary edema of smoke inhalation. We developed a synthetic smoke composed of carbon particles (mean diameter of 4.3 microns) to which toxins known to be in smoke, such as HCl or acrolein, could be added one at a time. We delivered synthetic smoke to dogs for 10 min and monitored extravascular lung water (EVLW) accumulation thereafter with a double-indicator thermodilution technique. Final EVLW correlated highly with gravimetric values (r = 0.93, P less than 0.01). HCl in concentrations of 0.1-6 N when added to heated carbon (120 degrees C) and cooled to 39 degrees C produced airway damage but no pulmonary edema. Acrolein, in contrast, produced airway damage but also pulmonary edema, whereas capillary wedge pressures remained stable. Low-dose acrolein smoke (less than 200 ppm) produced edema in two of five animals with a 2- to 4-h delay. Intermediate-dose acrolein smoke (200-300 ppm) always produced edema at an average of 147 +/- 57 min after smoke, whereas high-dose acrolein (greater than 300 ppm) produced edema at 65 +/- 16 min after smoke. Thus acrolein but not HCl, when presented as a synthetic smoke, produced a delayed-onset, noncardiogenic, and peribronchiolar edema in a roughly dose-dependent fashion.     

Ligation of the bronchial artery in sheep attenuates early pulmonary changes following exposure to smoke.

Smoke inhalation can produce acute pulmonary edema. Previous studies have shown that the bronchial arteries are important in acute pulmonary edema occurring after inhalation of a synthetic smoke containing acrolein, a common smoke toxin. We hypothesized that inhalation of smoke from burning cotton, known to contain acrolein, would produce in sheep acute pulmonary edema that was mediated by the bronchial circulation. We reasoned that occluding the bronchial arteries would eliminate smoke-induced pulmonary edema, whereas occlusion of the pulmonary artery would not. Smoke inhalation increased lung lymph flow from baseline from 2.4 +/- 0.7 to 5.6 +/- 1.2 ml/0.5 h at 30 min (P < 0.05) to 9.1 +/- 1 ml/0.5 h at 4 h (P < 0.05). Bronchial artery ligation diminished and delayed the rise in lymph flow with baseline at 2.8 +/- 0.7 ml/0.5 h rising to 3.1 +/- 0. 8 ml/0.5 h at 30 min to 6.5 +/- 1.5 ml/0.5 h at 240 min (P < 0.05). Wet-to-dry ratio was 4.1 +/- 0.2 in control, 5.1 +/- 0.3 in smoke inhalation (P < 0.05), and 4.4 +/- 0.4 in bronchial artery ligation plus smoke-inhalation group. Smoke inhalation after occlusion of the right pulmonary artery resulted in a wet-to-dry ratio after 4 h in the right lung of 5.5 +/- 0.8 (P < 0.05 vs. control) and in the left nonoccluded lung of 5.01 +/- 0.7 (P < 0.05). Thus the bronchial arteries may be major contributors to acute pulmonary and airway edema following smoke inhalation because the edema occurs in the lung with the pulmonary artery occluded but not in the lungs with bronchial arteries ligated.     

Bronchial responsiveness and inflammation in guinea pigs exposed to acrolein

Bronchial hyperresponsiveness can be produced experimentally after inhalation of numerous nonimmunospecific stimuli; our objective was to determine whether acrolein, a component of cigarette smoke, could increase bronchial reactivity to intravenously administered acetylcholine in guinea pigs. Bronchial responsiveness was assessed twice before and 1, 2, 6, and 24 h after exposures to less than or equal to 0.01 (sham), 0.31, 0.67, 0.94, or 1.26 parts per million for 2 h (5-7 guinea pigs/group). To examine the possible relationships of responsiveness to inflammatory mediator release and cellular infiltration, bronchoalveolar lavage was performed in another 30 guinea pigs before (control) and 0, 1, 2, 6, or 24 h after exposures. Pulmonary resistance was increased immediately after exposure (5 min) and returned to control values within 30-60 min. Increased bronchial responsiveness was evident within 1 h and became maximal 2-4 h after exposure. The acetylcholine dose necessary to double resistance decreased from 104.2 +/- 7.3 to 79.6 +/- 15.9 at 1 h and was 32.5 +/- 7.9 at 2 h and 32.8 +/- 7.6 micrograms.kg-1 at 6 h. Increases in two eicosanoids, thromboxane B2 (from 167 +/- 21 to 314 +/- 77 pg/ml) and prostaglandin F2 alpha (from 98 +/- 20 to 285 +/- 62 pg/ml) occurred immediately after exposure, whereas an influx of neutrophils occurred 24 h later (from 2.2 +/- 1.2 to 11.3 +/- 3.6%). These temporal relationships suggest that neutrophil infiltration may be a sufficient but not a necessary condition for the onset of bronchial hyperresponsiveness and that injury to cells normally present in the lung are responsible for the mediators thought to influence bronchial responsiveness.     

Bronchial circulation in pulmonary artery occlusion and reperfusion

Obstruction of pulmonary arterial blood flow results in minimal biochemical and/or morphological changes in the involved lung. If the lung is reperfused, a syndrome of leukopenia and lung edema occurs. We used the radiolabeled microsphere technique to measure the response of the bronchial circulation in rabbits to acute pulmonary artery occlusion (PAO) and to pulmonary artery reperfusion. We found that the bronchial blood flow (Qbr) decreased from a base line of 0.37 +/- 0.10 to 0.09 +/- 0.04 (SE) ml.min-1.g dry lung-1 (P less than or equal to 0.05) after 4 h of PAO. In a separate group of animals, Qbr 24 h after PAO remained low (0.20 +/- 0.07 ml.min-1.g dry lung-1, P = 0.06). Qbr during PAO was inversely correlated with the wet-to-dry ratio after reperfusion (r = -0.68, P = 0.06). Qbr did not change during 4 h of reperfusion. We speculate that a critical level of Qbr may be necessary during PAO to prevent ischemia/reperfusion injury from occurring.     

Vasoactive mediators and pulmonary hypertension after cigarette smoke exposure in the guinea pig.

The pathogenesis of pulmonary hypertension in patients with chronic obstructive pulmonary disease is not understood. We have previously shown increased levels of mediators that control vasoconstriction (endothelin-1), vascular cell proliferation (endothelin-1 and vascular endothelial growth factor), and vasodilation (endothelial nitric oxide synthase) in the intrapulmonary arteries of animals exposed to cigarette smoke. To determine whether these mediators could be implicated in the structural remodeling of the arterial vasculature and increased pulmonary arterial pressure caused by chronic cigarette smoke exposure, guinea pigs were exposed to daily cigarette smoke for 6 mo. Pulmonary arterial pressures were measured. Intrapulmonary artery structure was analyzed by morphometry, artery mediator protein expression by immunohistochemistry, and artery mediator gene expression by laser capture microdissection and real-time RT-PCR. We found that the smoke-exposed animals developed increases in pulmonary arterial pressure and increased muscularization of the small pulmonary arteries. Gene expression and protein levels of all three mediators were increased, and pulmonary arterial pressure correlated both with the levels of mediator production and with the degree of arterial muscularization. We conclude that chronic smoke exposure produces increased vasoactive mediator expression in the small intrapulmonary arteries and that these mediators are associated with vascular remodeling as well as increased pulmonary arterial pressure. These findings support the idea that hypertension in chronic obstructive pulmonary disease is a result of direct cigarette smoke-mediated effects on the vasculature and suggest that interference with endothelin and VEGF production and activity or augmentation of nitric oxide levels may be beneficial.     

Proteomic identification of moesin upon exposure to acrolein

Background

Acrolein (allyl Aldehyde) as one of smoke irritant exacerbates chronic airway diseases and increased in sputum of patients with asthma and chronic obstructive lung disease. But underlying mechanism remains unresolved. The aim of study was to identify protein expression in human lung microvascular endothelial cells (HMVEC-L) exposed to acrolein.

Methods

A proteomic approach was used to determine the different expression of proteins at 8 h and 24 h after treatment of acrolein 30 nM and 300 nM to HMVEC-L. Treatment of HMVEC-L with acrolein 30 nM and 300 nM altered 21 protein spots on the two-dimensional gel, and these were then analyzed by MALDI-TOF MS.

Results

These proteins included antioxidant, signal transduction, cytoskeleton, protein transduction, catalytic reduction. The proteins were classified into four groups according to the time course of their expression patterns such as continually increasing, transient increasing, transient decreasing, and continually decreasing. For validation immunohistochemical staining and Western blotting was performed on lung tissues from acrolein exposed mice. Moesin was expressed in endothelium, epithelium, and inflammatory cells and increased in lung tissues of acrolein exposed mice compared with sham treated mice.

Conclusions

These results indicate that some of proteins may be an important role for airway disease exacerbation caused by acrolein exposure.

     

Chronic intrauterine pulmonary hypertension selectively modifies pulmonary artery smooth muscle cell gene expression

Pulmonary artery smooth muscle cell (PASMC) relaxation at birth results from an increase in cytosolic cGMP, cGMP-dependent and kinase-mediated activation of the Ca2+-sensitive K+ channel (KCa), and closure of voltage-operated Ca2+ channels (VOCC). How chronic intrauterine pulmonary hypertension compromises perinatal pulmonary vasodilation remains unknown. We tested the hypothesis that chronic intrauterine pulmonary hypertension selectively modifies gene expression to mitigate perinatal pulmonary vasodilation mediated by the cGMP kinase-KCa-VOCC pathway. PASMC were isolated from late-gestation fetal lambs that had undergone either ligation of the ductus arteriosus (hypertensive) or sham operation (control) at 127 days of gestation and were maintained under either hypoxic (approximately 25 Torr) or normoxic (approximately 120 Torr) conditions in primary culture. We studied mRNA levels for cGMP kinase Ialpha (PKG-1alpha), the alpha-chain of VOCC (Cav1.2), and the alpha-subunit of the KCa channel. Compared with control PASMC, hypertensive PASMC had decreased VOCC, KCa, and PKG-1alpha expression. In response to sustained normoxia, expression of VOCC and KCa channel decreased and expression of PKG-1alpha increased. In contrast, sustained normoxia had no effect on PKG-1alpha levels and an attenuated effect on VOCC and KCa channel expression in hypertensive PASMC. Protein expression of PKG-1alpha was consistent with the mRNA data. We conclude that chronic intrauterine pulmonary hypertension decreases PKG expression and mitigates the genetic effects of sustained normoxia on pulmonary vasodilation, because gene expression remains compromised even after sustained exposure to normoxia.     

Reduced exercise tolerance and pulmonary capillary recruitment with remote secondhand smoke exposure

Rationale

Flight attendants who worked on commercial aircraft before the smoking ban in flights (pre-ban FAs) were exposed to high levels of secondhand smoke (SHS). We previously showed never-smoking pre-ban FAs to have reduced diffusing capacity (Dco) at rest.

Methods

To determine whether pre-ban FAs increase their Dco and pulmonary blood flow () during exercise, we administered a symptom-limited supine-posture progressively increasing cycle exercise test to determine the maximum work (watts) and oxygen uptake () achieved by FAs. After 30 min rest, we then measured Dco and at 20, 40, 60, and 80 percent of maximum observed work.

Results

The FAs with abnormal resting Dco achieved a lower level of maximum predicted work and compared to those with normal resting Dco (mean±SEM; 88.7±2.9 vs. 102.5±3.1%predicted ; p = 0.001). Exercise limitation was associated with the FAs'' FEV₁ (r = 0.33; p = 0.003). The Dco increased less with exercise in those with abnormal resting Dco (mean±SEM: 1.36±0.16 vs. 1.90±0.16 ml/min/mmHg per 20% increase in predicted watts; p = 0.020), and amongst all FAs, the increase with exercise seemed to be incrementally lower in those with lower resting Dco. Exercise-induced increase in was not different in the two groups. However, the FAs with abnormal resting Dco had less augmentation of their Dco with increase in during exercise (mean±SEM: 0.93±0.06 vs. 1.47±0.09 ml/min/mmHg per L/min; p<0.0001). The Dco during exercise was inversely associated with years of exposure to SHS in those FAs with ≥10 years of pre-ban experience (r = −0.32; p = 0.032).

Conclusions

This cohort of never-smoking FAs with SHS exposure showed exercise limitation based on their resting Dco. Those with lower resting Dco had reduced pulmonary capillary recruitment. Exposure to SHS in the aircraft cabin seemed to be a predictor for lower Dco during exercise.     

Renal artery stent implantation in a patient with bilateral renal artery stenoses presenting with flash pulmonary edema

We describe a patient with a clinical presentation of moderate renal dysfunction, recurrent hospitalizations for congestive heart failure, and an episode of abrupt-onset pulmonary edema (flash pulmonary edema). Diagnostic angiography revealed triple-vessel coronary artery disease (CAD) and bilateral severe renal artery stenosis. This patient underwent successful bilateral renal artery stent implantation with marked improvement in his functional class without further recurrence of pulmonary edema.     

Depletion of pulmonary EC-SOD after exposure to hyperoxia

Extracellular superoxide dismutase (EC-SOD) is highly expressed in lung tissue. EC-SOD contains a heparin-binding domain that is sensitive to proteolysis. This heparin-binding domain is important in allowing EC-SOD to exist in relatively high concentrations in specific regions of the extracellular matrix and on cell surfaces. EC-SOD has been shown to protect the lung against hyperoxia in transgenic and knockout studies. This study tests the hypothesis that proteolytic clearance of EC-SOD from the lung during hyperoxia contributes to the oxidant-antioxidant imbalance that is associated with this injury. Exposure to 100% oxygen for 72 h resulted in a significant decrease in EC-SOD levels in the lungs and bronchoalveolar lavage fluid of mice. This correlated with a significant depletion of EC-SOD from the alveolar parenchyma as determined by immunofluorescence and immunohistochemistry. EC-SOD mRNA was unaffected by hyperoxia; however, there was an increase in the ratio of proteolyzed to uncut EC-SOD after hyperoxia, which suggests that hyperoxia depletes EC-SOD from the alveolar parenchyma by cutting the heparin-binding domain. This may enhance hyperoxic pulmonary injury by altering the oxidant-antioxidant balance in alveolar spaces.     

Redistribution of pulmonary EC-SOD after exposure to asbestos.

Inhalation of asbestos fibers leads to interstitial lung disease (asbestosis) characterized by inflammation and fibrosis. The pathogenesis of asbestosis is not fully understood, but reactive oxygen species are thought to play a central role. Extracellular superoxide dismutase (EC-SOD) is an antioxidant enzyme that protects the lung in a bleomycin-induced pulmonary fibrosis model, but its role has not been studied in asbestos-mediated disease. EC-SOD is found in high levels in the extracellular matrix of lung alveoli because of its positively charged heparin-binding domain. Proteolytic removal of this domain results in clearance of EC-SOD from the matrix of tissues. We treated wild-type C57BL/6 mice with 0.1 mg of crocidolite asbestos by intratracheal instillation and euthanized them 24 h later. Compared with saline- or titanium dioxide-treated control mice, bronchoalveolar lavage fluid (BALF) from asbestos-treated mice contained significantly higher total protein levels and increased numbers of inflammatory cells, predominantly neutrophils, indicating acute lung injury in response to asbestos. Decreased EC-SOD protein and activity were found in the lungs of asbestos-treated mice, whereas more EC-SOD was found in the BALF of these mice. The EC-SOD in the BALF was predominantly in the proteolyzed form, which lacks the heparin-binding domain. This redistribution of EC-SOD correlated with development of fibrosis 14 days after asbestos exposure. These data suggest that asbestos injury leads to enhanced proteolysis and clearance of EC-SOD from lung parenchyma into the air spaces. The depletion of EC-SOD from the extracellular matrix may increase susceptibility of the lung to oxidative stress during asbestos-mediated lung injury.     

Histamine-induced pulmonary edema distal to pulmonary arterial occlusion

Histological studies provide evidence that the bronchial veins are a site of leakage in histamine-induced pulmonary edema, but the physiological importance of this finding is not known. To determine if a lung perfused by only the bronchial arteries could develop pulmonary edema, we infused histamine for 2 h in anesthetized sheep with no pulmonary arterial blood flow to the right lung. In control sheep the postmortem extravascular lung water volume (EVLW) in both the right (occluded) and left (perfused) lung was 3.7 +/- 0.4 ml X g dry lung wt-1. Following histamine infusion, EVLW increased to 4.4 +/- 0.7 ml X g dry lung wt-1 in the right (occluded) lung (P less than 0.01) and to 5.3 +/- 1.0 ml X g dry wt-1 in the left (perfused) lung (P less than 0.01). Biopsies from the right (occluded) lungs scored for the presence of edema showed a significantly higher score in the lungs that received histamine (P less than 0.02). Some leakage from the pulmonary circulation of the right lung, perfused via anastomoses from the bronchial circulation, cannot be excluded but should be modest considering the low pressures in the pulmonary circulation following occlusion of the right pulmonary artery. These data show that perfusion via the pulmonary arteries is not a requirement for the production of histamine-induced pulmonary edema.     

Chronic oral exposure to the aldehyde pollutant acrolein induces dilated cardiomyopathy

Environmental triggers of dilated cardiomyopathy are poorly understood. Acute exposure to acrolein, a ubiquitous aldehyde pollutant, impairs cardiac function and cardioprotective responses in mice. Here, we tested the hypothesis that chronic oral exposure to acrolein induces inflammation and cardiomyopathy. C57BL/6 mice were gavage-fed acrolein (1 mg/kg) or water (vehicle) daily for 48 days. The dose was chosen based on estimates of human daily unsaturated aldehyde consumption. Compared with vehicle-fed mice, acrolein-fed mice exhibited significant (P < 0.05) left ventricular (LV) dilatation (LV end-diastolic volume 36 ± 8 vs. 17 ± 5 μl), contractile dysfunction (dP/dt(max) 4,697 ± 1,498 vs. 7,016 ± 1,757 mmHg/s), and impaired relaxation (tau 15.4 ± 4.3 vs. 10.4 ± 2.2 ms). Histological and biochemical evaluation revealed myocardial oxidative stress (membrane-localized protein-4-hydroxy-trans-2-nonenal adducts) and nitrative stress (increased protein-nitrotyrosine) and varying degrees of plasma and myocardial protein-acrolein adduct formation indicative of physical translocation of ingested acrolein to the heart. Acrolein also induced myocyte hypertrophy (~2.2-fold increased myocyte area, P < 0.05), increased apoptosis (~7.5-fold), and disrupted endothelial nitric oxide synthase in the heart. DNA binding studies, immunohistochemistry, and PCR revealed significant (P < 0.05) activation of nuclear factor-κB in acrolein-exposed hearts, along with upregulated gene expression of proinflammatory cytokines tumor necrosis factor-α and interleukin-1β. Long-term oral exposure to acrolein, at an amount within the range of human unsaturated aldehyde intake, induces a phenotype of dilated cardiomyopathy in the mouse. Human exposure to acrolein may have analogous effects and raise consideration of an environmental, aldehyde-mediated basis for heart failure.