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Background Although emphysema destroys alveolar structures progressively and causes death eventually, no drug has been discovered to prevent, intervene, and/or resolve this life-threatening disease. We recently reported that sulfated caffeic acid dehydropolymer CDSO3 is a novel potent triple-action inhibitor of elastolysis, oxidation, and inflammation in vitro, and therefore, a potential anti-emphysema agent. However, the in vivo therapeutic potency, duration and mode of actions, and effective route remain to be demonstrated. Methods Emphysema was induced in rats with human sputum elastase (HSE) combined with cigarette smoke extract (CSE). CDSO3 at 5, 30, or 100 [mu]g/kg was dosed to the lung or injected subcutaneously at 2, 6, or 24 h before or 1 or 24 h or 1 week after the HSE/CSE instillation. At 1 h or 48 h or on day 21-22 or day 28, lungs were examined for airway-to-blood injurious barrier damage; their elastolytic, oxidative, and inflammatory activities; lung luminal leukocytes infiltration; functional treadmill exercise endurance; and/or morphological airspace enlargement. Results CDSO3, when dosed to the lung at 30 or 100 [mu]g/kg, but not via systemic subcutaneous injection, significantly (43-93 %) attenuated HSE/CSE-induced (1) barrier damage measured by luminal hemorrhage and protein leak; (2) elastolytic, oxidative, and inflammatory activities measured with elastase, reduced glutathione, and TNF[alpha] levels, respectively; (3) luminal neutrophil infiltration and tissue myeloperoxidase activity; (4) functional impairment of exercise endurance; and (5) airspace enlargement, in both preventive and interventional dosing protocols. Notably, the effects were shown to last for 24 h at the greater 100-[mu]g/kg dose, and the 1-week-delayed administration was also capable of attenuating the development of emphysema. Conclusions CDSO3 is a novel, potent, long-acting, nonpeptidic macromolecule that inhibits HSE/CSE-induced elastolysis, oxidation, and inflammation in the lung and thereby attenuates the development of emphysema in rats, in both preventive and interventional manners, when administered locally to the lung., Author(s): Bhawana Saluja[sup.1] , Hua Li[sup.1] , Umesh R. Desai[sup.2] , Norbert F. Voelkel[sup.3] , Masahiro Sakagami[sup.1] Author Affiliations: (1) Department of Pharmaceutics, School of Pharmacy, Virginia Commonwealth University, 980533, [...]

Background Although emphysema destroys alveolar structures progressively and causes death eventually, no drug has been discovered to prevent, intervene, and/or resolve this life-threatening disease. We recently reported that sulfated caffeic acid dehydropolymer CDSO3 is a novel potent triple-action inhibitor of elastolysis, oxidation, and inflammation in vitro, and therefore, a potential antiemphysema agent. However, the in vivo therapeutic potency, duration and mode of actions, and effective route remain to be demonstrated. Methods Emphysema was induced in rats with human sputum elastase (HSE) combined with cigarette smoke extract (CSE). CDSO3 at 5, 30, or 100 µg/kg was dosed to the lung or injected subcutaneously at 2, 6, or 24 h before or 1 or 24 h or 1 week after the HSE/CSE instillation. At 1 h or 48 h or on day 21-22 or day 28, lungs were examined for airway-to-blood injurious barrier damage; their elastolytic, oxidative, and inflammatory activities; lung luminal leukocytes infiltration; functional treadmill exercise endurance; and/or morphological airspace enlargement. Results CDSO3,€ when dosed to the lung at 30 or 100 µg/ kg, but not via systemic subcutaneous injection, significantly (43-93 %) attenuated HSE/CSE-induced (1) barrier damage measured by luminal hemorrhage and protein leak; (2) elastolytic, oxidative, and inflammatory activities measured with elastase, reduced glutathione, and TNFα levels, respectively; (3) luminal neutrophil infiltration and tissue myeloperoxidase activity; (4) functional impairment of exercise endurance; and (5) airspace enlargement, in both preventive and interventional dosing protocols. Notably, the effects were shown to last for 24 h at the greater 100-µg/kg dose, and the 1-week-delayed administration was also capable of attenuating the development of emphysema. Conclusions CDSO3 is a novel, potent, long-acting, nonpeptidic macromolecule that inhibits HSE/CSE-induced elastolysis, oxidation, and inflammation in the lung and thereby attenuates the development of emphysema in rats, in both preventive and interventional manners, when administered locally to the lung. Keywords Emphysema * Elastolysis * Inflammation * Oxidation * Caffeic acid * Dehydropolymer, Abbreviations AAALAC Association for assessment and accreditation of laboratory animal care ANOVA Analysis of variance BAL Bronchoalveolar lavage BALF BAL fluid BCA Bicinchoninic assay βNADPH β-Nicotinamide adenine dinucleotide 2' phosphate [...]

Background We postulate that in adults there is an established lung structure maintenance program and that lung alveolar septal cells are undergoing both continuous apoptosis and proliferation. Whereas lung cell apoptosis has been recognized in human emphysema, little is known about cell proliferation. Methods Using a novel rat model of emphysema, induced by intratracheal instillation of cigarette smoke extract (CSE), we investigated the dynamics of emphysematous lung destruction. Emphysematous lung destruction was determined by measuring mean linear intercept and destructive index. Lung injury and repair were assessed by immunohistochemistry and Western blot analysis for active caspase-3 and proliferating cell nuclear antigen (PCNA) after 4, 8, and 12 weeks of CSE instillations. Results The emphysematous lung tissue destruction was present at 4 weeks of CSE treatment and progressed to 8 weeks. Spontaneous repair began at 12 weeks. Treatment with a peroxisome proliferator activated receptor (PPAR)α+γ agonist or granulocyte and macrophage-colony stimulating factor (GM-CSF) for 4 weeks prevented the progression of emphysematous lung destruction and decreased the number of caspase-3-positive cells. Conclusion Apoptosis and cell proliferation occur in this new model of emphysema. Treatment with a PPARα+γ agonist or GM-CSF can inhibit the progression of emphysematous alveolar septal destruction by decreasing alveolar cell apoptosis. Keywords Emphysema * Apoptosis * Cell proliferation * PPARα+γ * GM-CSF, Introduction It has been generally accepted that the adult lung is a terminally differentiated organ and that lung structural cells do not rapidly turnover, as is the case, for example, [...]

Chronic inflammation, imbalance of proteolytic and anti-proteolytic activities, oxidative stress, and apoptosis of lung structural cells contribute to the pathogenesis of COPD. Prostacyclin protects cells against apoptosis, has anti-inflammatory properties, partially prevents cigarette smoke extract (CSE)-induced apoptosis of the pulmonary endothelium, and thus may be relevant in the pathogenesis of emphysema. We determined whether a synthetic stable prostacyclin analog, beraprost sodium (BPS), attenuates the development of CSE-induced emphysema and elucidated the molecular mechanisms involved in its effect. Sprague-Dawley rats were treated with BPS and injected with CSE once a week for 3 wk. We measured the DNA damage of cells, the expression of caspase-3, and the activity of matrix metalloproteinase (MMP)-2 and MMP-9. We also analyzed TNF[alpha] and IL-1[beta] concentrations and the serum antioxidant activity. BPS prevented the development of CSE-induced emphysema, resulting in significant attenuation in alveolar enlargement and pulmonary parenchymal destruction. BPS inhibited pulmonary apoptosis and induction of MMP-2 and MMP-9 activity. Moreover, the protective effect of BPS was associated with a reduction of the expression of proinflammatory cytokines including TNF[alpha] and IL-1[beta] and a normalized biological oxidant activity. BPS introduces all these events, probably by activating cAMP signaling through acting specific prostacyclin receptors. In conclusion, BPS protects against the development of CSE-induced emphysema by attenuating apoptosis, inhibiting proteolytic enzyme activity, reducing inflammatory cytokine levels, and augmenting antioxidant activity. BPS may potentially represent a new therapeutic option in the prevention of emphysema in humans in prospect. apoptosis; inflammation; rat; oxidative stress; matrix metalloproteinase

Increasing evidence demonstrates that interleukin (IL)-32 is a proinflammatory cytokine, inducing IL-1[alpha], IL-1[beta], IL-6, tumor necrosis factor (TNF)-[alpha], and chemokines via nuclear factor (NF)-[kappa]B, p38 mitogen-activated protein kinase (MAPK), and activating protein (AP)-1 activation. Here we report that IL-32 is expressed and is also functional in human vascular endothelial cells (EC) of various origins. Compared with primary blood monocytes, high levels of IL-32 are constitutively produced in human umbilical vein EC (HUVEC), aortic macrovascular EC, and cardiac as well as pulmonary microvascular EC. At concentrations as low as 0.1 ng/ml, IL-1[beta] stimulated IL-32 up to 15-fold over constitutive levels, whereas 10 ng/ml of TNF[alpha] or 100 ng/ml of lipopolysaccharide (LPS) were required to induce similar quantities of IL-32. IL-1[beta]-induced IL-32 was reduced by inhibition of the I[kappa]B kinase-[beta]/NF-[kappa]B and ERK pathways. In addition to IL-1[beta], pro-coagulant concentrations of thrombin or fresh platelets increased IL-32 protein up to 6-fold. IL-1[beta] and thrombin induced an isoformswitch in steady-state mRNA levels from IL-32[alpha]/[gamma] to [beta]/[epsilon]. Adult EC responded in a similar fashion. To prove functionality, we silenced endogenous IL-32 with siRNA, decreasing intracellular IL-32 protein levels by 86%. The knockdown of IL-32 resulted in reduction of constitutive as well as IL-1[beta]-induced intercellular adhesion molecule-1 (ICAM-1) (of 55% ancl 54%, respectively), IL-1[alpha] (of 62% and 43%), IL-6 (of 53% and 43%), and IL-8 (of 46% and 42%). In contrast, the anti-inflammatory/anti-coagulant CD141/thrombomodulin increased markedly when IL-32 was silenced. This study introduces IL-32 as a critical regulator of endothelial function, expanding the properties of this cytokine relevant to coagulation, endothelial inflammation, and atherosclerosis. Atherosclerosis | Coagulation | Inflammation

Emphysema is one manifestation of a group of chronic, obstructive, and frequently progressive destructive lung diseases. Cigarette smoking and air pollution are the main causes of emphysema in humans, and cigarette smoking causes emphysema in rodents. This review examines the concept of a homeostatically active lung structure maintenance program that, when attacked by proteases and oxidants, leads to the loss of alveolar septal cells and airspace enlargement. Inflammatory and noninflammatory mechanisms of disease pathogenesis, as well as the role of the innate and adaptive immune systems, are being explored in genetically altered animals and in exposure models of this disease. These recent scientific advances support a model whereby alveolar destruction resulting from a coalescence of mechanical forces, such as hyperinflation, and more recently recognized cellular and molecular events, including apoptosis, cellular senescence, and failed lung tissue repair, produces the clinically recognized syndrome of emphysema., ... animals have really two environments: a milieu exterieur in which the organism is situated and a milieu interieur in which the tissue elements live.--All the vital mechanisms, varied as [...]

Small airway fibrosis (bronchiolitis obliterans syndrome) is the primary obstacle to long-term survival following lung transplantation. Here, we show the importance of functional microvasculature in the prevention of epithelial loss and fibrosis due to rejection and for the first time, relate allograft microvascular injury and loss of tissue perfusion to immunotherapy-resistant rejection. To explore the role of alloimmune rejection and airway ischemia in the development of fibroproliferation, we used a murine orthotopic tracheal transplant model. We determined that transplants were reperfused by connection of recipient vessels to donor vessels at the surgical anastomosis site. Microcirculation through the newly formed vascular anastomoses appeared partially dependent on VEGFR2 and CXCR2 pathways. In the absence of immunosuppression, the microvasculature in rejecting allografts exhibited vascular complement deposition, diminished endothelial CD31 expression, and absent perfusion prior to the onset of fibroproliferation. Rejecting grafts with extensive endothelial cell injury were refractory to immunotherapy. After early microvascular loss, neovascularization was eventually observed in the membranous trachea, indicating a reestablishment of graft perfusion in established fibrosis. One implication of this study is that bronchial artery revascularization at the time of lung transplantation may decrease the risk of subsequent airway fibrosis., Introduction The major obstacle to survival following lung transplantation is the bronchiolitis obliterans syndrome (BOS) (1), which is clinically defined by a decline in ventilatory function and histologically characterized by [...]

Lipopolysaccharide (LPS) induces acute lung injury (ALI) via Toll-like receptor 4 (TLR4)-mediated MAPK activation. The lipid A fraction of LPS is considered to be the active moiety, but whether the lipid A-TLR4 interaction accounts completely for ALI-associated MAPK activation in vivo has not been determined. The lipid A fraction of LPS induces a discrete MAPK activation pattern in murine ALI. Mice (C57BL/6J, C3H/HeJ) were treated with intratracheal instillations of purified lipid A or LPS (10, 30, and 100 [micro]g per mouse) or vehicle. ALI was assessed by histology. Chromogenic myeloperoxidase (MPO) activity was measured in lung homogenates. MAPK expression was quantified by immunoblotting. In vitro ERK inhibitor studies using thioglycollate-elicited macrophages were also performed. MPO increased in a dose- and time-responsive fashion. Notably, MPO was 2.4-fold greater after lipid A compared with LPS and vehicle at 6 h after instillation (lipid A, 0.88 [+ or -] 0.25 vs. LPS, 0.37 [+ or -] 0.21 optical density units*[min.sup.-1]*[mg.sup.-1]; P < 0.05). However, ALI scores were comparable at 6 and 24 h between LPS and lipid A. MPO was also comparable in vehicle-treated or C3H/HeJ mice treated with LPS or lipid A at 6 and 24 h. Phospho-ERK activation was pronounced at 6 and 24 h after lipid A but not LPS treatment. In vitro studies confirmed the relationship between phospho-ERK activation and cytokine expression in macrophage stimulated with either LPS or lipid A. Compared with whole LPS, the lipid A fraction is associated with amplified whole lung MPO and ERK activation 6 h after intratracheal instillation in mice. [Kdo.sub.2]-lipid A; lipopolysaccharide; extracellular signal-regulated kinase p44/42

Proliferation of cyst-lining epithelial cells is an integral part of autosomal dominant polycystic kidney disease (ADPKD) cyst growth. Cytokines and growth factors within cyst fluids are positioned to induce cyst growth. Vascular endothelial growth factor (VEGF) is a pleiotropic growth factor present in ADPKD liver cyst fluids (human 1,128 [+ or -] 78, mouse 2,787 [+ or -] 136 pg/ml) and, to a lesser extent, in ADPKD renal cyst fluids (human 294 [+ or -] 41, mouse 191 [+ or -] 90 pg/ml). Western blotting showed that receptors for VEGF (VEGFR1 and VEGFR2) were present in both normal mouse bile ducts and pkd2(WS25/-) liver cyst epithelial cells. Treatment of pkd2(WS25/-) liver cyst epithelial cells with VEGF (50-50,000 pg/ml) or liver cyst fluid induced a proliferative response. The effect on proliferation of liver cyst fluid was inhibited by SU-5416, a potent VEGF receptor inhibitor. Treatment of pkd2(WS25/-) mice between 4 and 8 mo of age with SU-5416 markedly reduced the cyst volume density of the liver (vehicle 9.9 [+ or -] 4.3%, SU-5416 1.8 [+ or -] 0.7% of liver). SU-5416 treatment between 4 and 12 mo of age markedly protected against increases in liver weight [pkd2(+/+) 4.8 [+ or -] 0.2%, pkd2(WS25/-)-vehicle 10.8 [+ or -] 1.9%, pkd2(WS25/-)-SU-5416 4.8 [+ or -] 0.4% body wt]. The capacity of VEGF signaling to induce in vitro proliferation of pkd2(WS25/-) liver cyst epithelial cells and inhibition of in vivo VEGF signaling to retard liver cyst growth in pkd2(WS25/-) mice indicates that the VEGF signaling pathway is a potentially important therapeutic target in the treatment of ADPKD liver cyst disease. autosomal dominant polycystic kidney disease; SU-5416; growth factors; cytokines doi:10.1152.ajpcell.00038.2007

Severe pulmonary hypertension (SPH) is characterized by precapillary arteriolar lumen obliteration, dramatic right ventricular hypertrophy, and pericardial effusion. Our recently published rat model of SPH recapitulates major components of the human disease. We used this model to develop new treatment strategies for SPH. SPH in rats was induced using VEGF receptor blockade in combination with chronic hypoxia. A large variety of drugs used in this study, including anticancer drugs (cyclophosphamide and paclitaxel), the angiotensin-converting enzyme inhibitor lisinopril, the antiangiogenic agent thalidomide, and the peroxisome proliferator-actived receptor-[gamma]-agonist PGJ2, failed to decrease mean pulmonary artery pressure (PAP) or right ventricular hypertrophy. In contrast, treatment of rats with established SPH with simvastatin markedly reduced mean PAP and right ventricular hypertrophy, and this reduction was associated with caspase-3 activation and pulmonary microvascular endothelial cell apoptosis. Simvastatin partially restored caveolin-1, caveolin-2, and phospho-caveolin expression in vessel walls. In rat primary pulmonary microvascular endothelial cells, simvastatin induced caspase 3 activation and Rac 1 expression while suppressing Rho A and attenuated levels of Akt and ERK phosphorylation. We conclude that simvastatin is effective in inducing apoptosis in hyperproliferative pulmonary vascular lesions and could be considered as a potential drug for treatment of human SPH. statins

We have previously hypothesized that the development of severe angio-proliferative pulmonary hypertension is associated with not only initial endothelial cell (EC) apoptosis followed by the emergence of apoptosis-resistant proliferating EC but also with proliferation of vascular smooth muscle cells (VSMC). We have demonstrated that EC death results in the selection of an apoptosis-resistant, proliferating, and phenotypically altered EC phenotype. We postulate here that the initial apoptosis of EC induces the release of mediators that cause VSMC proliferation. We cultured EC in an artificial capillary Cell-Max system designed to simulate the highly efficient functions of the human capillary system. We induced apoptosis of microvascular EC using shear stress and the combined VEGF receptor (VEGFR-1 and -2) inhibitor SU-5416. Flow cytometry for the proliferation marker bromodeoxyuridine showed that serum-free medium conditioned by apoptosed EC induced proliferation of VSMC, whereas serum-free medium conditioned by nonapoptosed EC did not. We also show that medium conditioned by apoptosed EC is characterized by increased concentrations of transforming growth factor (TGF)-[beta]1 and VEGF compared with medium conditioned by nonapoptosed EC and that TGF-[beta]1 blockade prevented the proliferation of cultured VSMC. In conclusion, EC death induced by high shear stress and VEGFR blockade leads to the production of factors, in particular TGF-[beta]1, that activate VSMC proliferation. shear stress; vascular endothelial growth factor receptor; blockade; pulmonary microvascular endothelial cells doi: 10.1152/ajplung.00111.2005

Vascular endothelial growth factor (VEGF) is a pluripotent growth and permeability factor that has a broad impact on endothelial cell function. The lung tissue is very rich in this protein; many different lung cells produce VEGF and also respond to VEGF. VEGF is critical for the development of the lung and serves as a maintenance factor during adult life. In addition to the physiological functions of this protein, there is increasing evidence that VEGF also plays a role in several acute and chronic lung diseases, such as acute lung injury, severe pulmonary hypertension, and emphysema. Here we provide a comprehensive overview of the rapidly expanding literature.

Human herpesvirus-8 (HHV-8) may be responsible for causing pulmonary hypertension in some people, according to a study of 30 patients. Lung tissue biopsy samples from 10 of the 16 patients with primary pulmonary hypertension tested positive for HHV-8. Pathological analysis of the samples revealed similarities with Kaposi's sarcoma tumors on the skin of HIV patients. Kaposi's sarcoma is also linked to HHV-8 infection.

To determine whether disruption of vascular endothelial growth factor (VEGF)-VEGF receptor (VEGFR) signaling in the newborn has long-term effects on lung structure and function, we injected 1-day-old newborn rat pups with a single dose of Su-5416, a VEGFR inhibitor, or vehicle (controls). Lungs from infant (3-wk-old) and adult (3- to 4-mo-old) rats treated with Su-5416 as newborns showed reductions in arterial density (82 and 31%, respectively) and alveolar counts (45 and 29%) compared with controls. Neonatal treatment with Su-5416 increased right ventricle weight to body wt ratios (4.2-fold and 2.0-fold) and pulmonary arterial wall thickness measurements (2.7-fold and 1.6-fold) in infant and adult rats, respectively, indicating marked pulmonary hypertension. We conclude that treatment of newborn rats with the VEGFR inhibitor Su-5416 impaired pulmonary vascular growth and postnatal alveolarization and caused pulmonary hypertension and that these effects were long term, persisting well into adulthood. angiogenesis; postnatal lung development; alveogenesis; bronchopulmonary dysplasia; pulmonary vascular development; vascular endothelial growth factor

BQ-123 is a novel endothelin type A receptor antagonist that protects the lungs from edematous lung injury caused by leukotoxin 9,10-epoxy-12-octadecenoate (Lx). Injection of BQ-123 into rat pulmonary rat artery reduces Lx-induced increases in lung weight, pulmonary capillary filtration coefficient, lactic dehydrogenase activity and endothelin levels. It also attenuated the effect of endothelin 1.

The cyclooxygenase (COX)-2 enzyme is an isoform of COX that mediates hypoxia-induced pulmonary hypertension and pulmonary vascular remodeling. In perfused rat lungs, acute hypoxia increased COX-2 in the lung. A nitric oxide (NO) synthase inhibitor attenuated hypoxia-induced COX-2 expression, but this effect was suppressed by inhibitors of protein kinase A and C. In contrast, chronic hypoxia had no effect on COX-2 expression. These data indicate that hypoxia induces COX-2 production.

Endotoxin increases bovine RBC adhesion to bovine pulmonary artery endothelial cells (BPAEC) monolayers in a concentration-dependent manner requiring divalent cations. Phosphatidylserine decreases RBC adhesion to endothelium cells while antioxidants enhance RBC adhesion. Neutrophils and monocytes, important in intravascular inflammation, cling to the vascular endothelium to release mediators like tumor necrosis factor-alpha (TNF-alpha), interlukin-1beta, and reactive oxygen species.

Leukotoxin, 9,10-epoxy-12-octadecenoate (Lx), causes lung edema through activation of vascular nitric oxide synthetase and oxidant stress. Lung weight increases in a dose-dependent manner but weight gain does not increase the pulmonary artery pressure. A lower dose of Lx produces a change in lung vascular permeability without raising microvascular pressure. Pretreatment of tissue with Ng-monomethyl-L-arginine, superoxide dimutase, and human oxyhemoglobin inhibited Lx-produced lung edema.

Leukotoxin (Lx), 9,10-epoxy-12-octadecenoate, induces vasodilation in rat lungs, with the vasodilatory component being dependent on the relaxation factor derived from endothelium. A biphasic response prior to vasodilation occurs in rats infused with Lx, having enhanced pulmonary vascular tone. Lx increases the pressor response to angiotensin II and the magnitude of hypoxic contraction of pulmonary arterial rings.

Inhibition of angiogenesis decreases alveolarization in the developing rat lung. Am J Physiol Lung Cell Mol Physiol 279: L600-L607, 2000.--To determine whether angiogenesis is necessary for normal alveolarization, we studied the effects of two antiangiogenic agents, thalidomide and fumagillin, on alveolarization during a critical period of lung growth in infant rats. Newborn rats were treated with daily injections of fumagillin, thalidomide, or vehicle during the first 2 wk of life. Compared with control treatment, fumagillin and thalidomide treatment reduced lung weight-to-body weight ratio and pulmonary arterial density by 20 and 36%, respectively, and reduced alveolarization by 22%. Because these drugs potentially have nonspecific effects on lung growth, we also studied the effects of Su-5416, an inhibitor of the vascular endothelial growth factor receptor known as kinase insert domain-containing receptor/fetal liver kinase (KDR/flk)-1. As observed with the other antiangiogenic agents, Su-5416 treatment decreased alveolarization and arterial density. We conclude that treatment with three different antiangiogenic agents attenuated lung vascular growth and reduced alveolarization in the infant rat. We speculate that angiogenesis is necessary for alveolarization during normal lung development and that injury to the developing pulmonary circulation during a critical period of lung growth can contribute to lung hypoplasia. bronchopulmonary dysplasia; congenital diaphragmatic hernia; fumagillin; lung growth; lung hypoplasia; pulmonary circulation; pulmonary hypertension; thalidomide; vascular endothelial growth factor

Pulmonary edema is a major cause of sickness and death in mountain climbers. It occurs when fluid collects in the lungs. A study published in 2002 showed that the beta agonist drug salmeterol can reduce the risk of pulmonary edema if inhaled before the climb.

Smooth Muscle--Mediated Connective Tissue Remodeling in Pulmonary Hypertension PERSISTENT PULMONARY HYPERTENsionin infancy leads to severe lung vascular changes that include marked hypertrophy, extension of vascular smooth muscle to small vessels, [...]