Right ventricular outflow tract function in chronic obstructive pulmonary disease

BACKGROUND

It is clinically important to evaluate the severity of right ventricular (RV) overload in patients with chronic obstructive pulmonary disease (COPD), which is often associated with changes in the structure and the function of the right ventricle. Noninvasive and reliable assessment of RV function would be an essential determinant of RV load and a clinically useful factor for assessing cardiovascular risk in COPD patients.

OBJECTIVE

The aim of this study was to investigate the clinical application value of right ventricular outflow tract (RVOT) systolic function measured by transthoracic echocardiography in patients with COPD.

PATIENTS AND METHODS

We prospectively investigated COPD male patients and compared them with healthy controls. In addition to RV conventional echocardiographic parameters, RVOT size and fractional shortening (RVOT-FS) parameters were also assessed.

RESULTS

Fifty-five COPD patients (all men; mean age, 62 ± 9 years) participated in the study, and were compared with a control group consisting of 21male, healthy, nonsmoking subjects with a mean age of 58 ± 11 years. The RVOT-FS was impaired in COPD patients than healthy controls (27.8 ± 15.5 vs. 57.5 ± 8.6, p < 0.001), and was correlated positively with tricuspid annular plane systolic excursion (TAPSE; r = 0.583, p < 0.001) and pulmonary acceleration time (r = 0.666, p < 0.001) and inversely with pulmonary artery systolic pressure (r = 0.605, p < 0.001) and functional capacity(r = - 0.589, p < 0.001). There was a statistically significant difference in RVOT-FS among the COPD subgroups with regard to New York Heart Association functional classification (p < 0.001).

CONCLUSION

The RVOT-FS is a noninvasive easily applicable measure of RV systolic function and is well correlated with functional capacity in COPD patients. Its combination with long-axis measurements via TAPSE and transtricuspid Doppler analysis may provide a comprehensive evaluation of the RV performance in COPD patients.

Activation of RhoA/Rho-kinase pathway accounts for pulmonary endothelial dysfunction in patients with chronic obstructive pulmonary disease

Recent evidence suggests that activation of RhoA/Rho-kinase accounts for systemic and pulmonary endothelial dysfunction in smokers with normal lung function. However, its role in patients with chronic obstructive pulmonary disease (COPD) has not yet been investigated. The aim of this study was to evaluate the regulation of RhoA/Rho-kinase pathway and pulmonary endothelial dysfunction in patients with COPD. Pulmonary arteries were obtained from nonsmokers (control subjects) and patients with nonhypoxemic and hypoxemic COPD (n = 6–7/group). Endothelium-dependent and -independent relaxations were evaluated by acetylcholine and sodium nitroprusside, respectively. Gene and protein expressions of endothelial nitric oxide synthase (eNOS) were measured by RT-PCR, Western blot, and immunohistochemistry. Nitrate, cGMP, and endothelin-1 (ET-1) concentrations, as well as Rho-kinase activity were measured by ELISA. Protein expressions of total RhoA and GTP-RhoA were measured by Western blot and pull-down assay, respectively. Endothelium-dependent relaxation, and nitrate and cGMP levels were significantly reduced in pulmonary arteries of COPD patients as compared with control subjects. Conversely, activity of RhoA/Rho-kinase was increased in pulmonary arteries of COPD patients as compared with control subjects. In patients with COPD, pulmonary endothelial dysfunction was related to the downregulation of eNOS activity and upregulation of RhoA/Rho-kinase activity.

Effects of different pulmonary vasodilators on arterial saturation in a model of pulmonary hypertension

Background

Approved therapies for pulmonary arterial hypertension can induce oxygen desaturation when administered to patients with secondary forms of pulmonary hypertension (PH), probably due to an increase in ventilation/perfusion mismatch. Thus, so far these treatments have largely failed in secondary forms of PH.

Methods

We established an animal model of heterogeneous lung ventilation to evaluate the desaturation potential of mechanistically distinct vasoactive drugs launched or currently in clinical development for the treatment of PH. Single-lung ventilation was induced in five groups (N = 6) of anesthetized minipigs (7 weeks, 4 to 5 kg BW), and their hemodynamic parameters were monitored before and after intravenous injection of control (vehicle only), endothelin antagonist (bosentan; 0.3, 1, 3, 10 mg/kg), phosphodiesterase type 5 inhibitor (sildenafil; 3, 10, 30, 100 µg/kg), and soluble guanylate cyclase stimulators (BAY 41–8543 and riociguat; 1, 3, 10, 30 µg/kg). Cumulative doses were administered before successive unilateral ventilation cycles. The doses were chosen to achieve equal effect on blood pressure by the different pharmacologic principles.

Results

Single-lung ventilation resulted in transient increases in mean pulmonary artery pressure (mPAP) and desaturation. In contrast to control, all drugs dose-dependently decreased hypoxic mPAP (a positive treatment effect) and increased area under the arterial hemoglobin saturation curve (unwanted desaturation effect). Riociguat and bosentan reduced hypoxic mPAP to the greatest extent, while the soluble guanylate cyclase stimulators riociguat and BAY 41–8543 lowered arterial oxygen saturation of hemoglobin the least.

Conclusions

Future investigations will be required to confirm these findings in clinical settings.

The interaction of endothelin-1 and TGF-β1 mediates vascular cell remodeling

BACKGROUND

Pulmonary arterial hypertension is characterized by increased thickness of pulmonary vessel walls due to both increased proliferation of pulmonary arterial smooth muscle cell (PASMC) and deposition of extracellular matrix. In patients suffering from pulmonary arterial hypertension, endothelin-1 (ET-1) synthesis is up-regulated and may increase PASMC activity and vessel wall remodeling through transforming growth factor beta-1 (TGF-β1) and connective tissue growth factor.

OBJECTIVE

To assess the signaling pathway leading to ET-1 induced proliferation and extracellular matrix deposition by human PASMC.

METHODS

PASMC were serum starved for 24 hours before stimulation with either ET-1 and/or TGF-β1. ET-1 was inhibited by Bosentan, ERK1/2 mitogen activated protein kinase (MAPK) was inhibited by U0126 and p38 MAPK was inhibited by SB203580.

RESULTS

ET-1 increased PASMC proliferation when combined with serum. This effect involved the mitogen activated protein kinases (MAPK) ERK1/2 MAPK and was abrogated by Bosentan which caused a G1- arrest through activation of p27((Kip)). Regarding the contribution of extracellular matrix deposition in vessel wall remodeling, TGF-β1 increased the deposition of collagen type-I and fibronectin, which was further increased when ET-1 was added mainly through ERK1/2 MAPK. In contrast, collagen type-IV was not affected by ET-1. Bosentan dose-dependently reduced the stimulatory effect of ET-1 on collagen type-I and fibronectin, but had no effect on TGF-β1.

CONCLUSION AND CLINICAL RELEVANCE

ET-1 alone does not induce PASMC proliferation and extracellular matrix deposition. However, ET-1 significantly up-regulates serum induced proliferation and TGF-β1 induced extracellular matrix deposition, specifically of collagen type-I and fibronectin. The synergistic effects of ET-1 on serum and TGF-β1 involve ERK1/2 MAPK and may thus present a novel mode of action in the pathogenesis of pulmonary arterial hypertension.

Pulmonary hypertension in chronic obstructive and interstitial lung diseases

The purpose of the present review is to summarize the current knowledge on PH in relation to COPD and ILD from a clinical perspective with emphasis on diagnosis, biomarkers, prevalence, impact, treatment, and practical implications. PH in COPD and ILD is associated with a poor prognosis, and is considered one of the most frequent types of PH. However, the prevalence of PH among patients with COPD and ILD is not clear. The diagnosis of PH in chronic lung disease is often established by echocardiographic screening, but definitive diagnosis requires right heart catheterization, which is not systematically performed in clinical practice. Given the large number of patients with chronic lung disease, biomarkers to preclude or increase suspicion of PH are needed. NT-proBNP may be used as a rule-out test, but biomarkers with a high specificity for PH are still required. It is not known whether specific treatment with existent drugs effective in pulmonary arterial hypertension (PAH) is beneficial in lung disease related PH. Studies investigating existing PAH drugs in animal models of lung disease related PH have indicated a positive effect, and so have case reports and open label studies. However, treatment with systemically administered pulmonary vasodilators implies the risk of worsening the ventilation-perfusion mismatch in patients with lung disease. Inhaled vasodilators may be better suited for PH in lung disease, but new treatment modalities are also required.

Intermedin modulates hypoxic pulmonary vascular remodeling by inhibiting pulmonary artery smooth muscle cell proliferation

BACKGROUND

Hypoxic pulmonary arterial hypertension (PAH) is a disabling disease with limited treatment options. Hypoxic pulmonary vascular remodeling is a major cause of hypoxic PAH. Pharmacological agents that can inhibit the remodeling process may have great therapeutic value.

OBJECTIVE

To examine the effect of intermedin (IMD), a new calcitonin gene-related peptide family of peptide, on hypoxic pulmonary vascular remodeling.

METHODS

Rats were exposed to normoxia or hypoxia (∼10% O(2)), or exposed to hypoxia and treated with IMD, administered by an implanted mini-osmotic pump (6.5 μg/rat/day), for 4 weeks. The effects of IMD infusion on the development of hypoxic PAH and right ventricle (RV) hypertrophy, on pulmonary vascular remodeling, on pulmonary artery smooth muscle cell (PASMC) proliferation and apoptosis, and on the activations of l-arginine nitric oxide (NO) pathway and endoplasmic reticulum stress apoptotic pathway were examined.

RESULTS

Rats exposed to hypoxia developed PAH and RV hypertrophy. IMD treatment alleviated PAH and prevented RV hypertrophy. IMD inhibited hypoxic pulmonary vascular remodeling as indicated by reduced wall thickness and increased lumen diameter of pulmonary arterioles, and decreased muscularization of distal pulmonary vasculature in hypoxia-exposed rats. IMD treatment inhibited PASMC proliferation and promoted PASMC apoptosis. IMD treatment increased tissue level of constitutive NO synthase activity and tissue NO content in lungs, and enhanced l-arginine uptake into pulmonary vascular tissues. IMD treatment increased cellular levels of glucose-regulated protein (GRP) 78 and GRP94, two major markers of endoplasmic reticulum (ER) stress, and increased caspase-12 expression, the ER stress-specific caspase, in lungs and cultured PASMCs.

CONCLUSIONS

These results demonstrate that IMD treatment attenuates hypoxic pulmonary vascular remodeling, and thereby hypoxic PAH mainly by inhibiting PASMC proliferation. Promotion of PASMC apoptosis may also contribute to the inhibitory effect of IMD. Activations l-arginine-NO pathway and of ER stress-specific apoptosis pathway could be the mechanisms mediating the anti-proliferative and pro-apoptotic effects of IMD.

Pulmonary artery distensibility in chronic obstructive pulmonary disease

BACKGROUND

Pulmonary hypertension (PH) is an important complication in the natural history of chronic obstructive pulmonary disease (COPD) and is caused by the remodeling of pulmonary arteries impairing the distensibility and stiffness of the major pulmonary arteries.

OBJECTIVES

To evaluate the pulmonary artery distensibility by transthoracic echocardiography in patients with COPD.

METHOD

We prospectively investigated COPD male patients and compared with healthy controls. In addition to right ventricle (RV) conventional echocardiographic parameters, right pulmonary artery fractional shortening(RPA-FS) and new pulmonary artery stiffness (PAS) parameters were compared.

RESULTS

Fifty-four COPD patients participated in the study and compared with a control group consisting of 24, all men, healthy, nonsmoking subjects. Six patients were excluded from study due to poor quality of echocardiographic recordings. The distensibility of PA evaluated by the RPA-FS parameter was found to be significantly lower in patients with COPD than it was in normal subjects (13.3 ± 8.1 vs. 27.6 ± 4.9,P :< 0.001) and correlated positively with tricuspid annular systolic excursion (TAPSE) (r = 0.566, P < 0.001) and pulmonary acceleration time (r = 0.607, P < 0.001) and correlated inversely with pulmonary artery systolic pressure (r = -0.587, P < 0.001), PAS(r = -0.479, P < 0.001) and functional capacity (r = -0.586, P < 0.001). Similar to this, PAS found to be impaired in COPD patients (29.5 ± 13.6 vs. 15.7 ± 4.1, P < 0.001) and correlated inversely RPA-FS (r = -0.479, P < 0.001). There were statistically significant difference for pulmonary artery distensibility (RPA-FS) and PAS parameters among the COPD subgroups with regard to NYHA functional capacity (P < 0.001).

CONCLUSION

In this study, we found that PAS and distensibility were worsened in COPD patients and correlated with decreased functional capacity.

Defective alterations in the collagen network to prostacyclin in COPD lung fibroblasts

BACKGROUND

Prostacyclin analogs are potent vasodilators and possess anti-inflammatory properties. However, the effect of prostacyclin on extracellular matrix (ECM) in COPD is not well known. Collagen fibrils and proteoglycans are essential ECM components in the lung and fibroblasts are key players in regulating the homeostasis of ECM proteins. The aim was to study the synthesis of prostacyclin and its effect on fibroblast activity and ECM production, and in particular collagen I and the collagen-associated proteoglycans biglycan and decorin.

METHODS

Parenchymal lung fibroblasts were isolated from lungs from COPD patients (GOLD stage IV) and from lungs and transbronchial biopsies from control subjects. The prostacyclin analog iloprost was used to study the effect of prostacyclin on ECM protein synthesis, migration, proliferation and contractile capacity of fibroblasts.

RESULTS

TGF-β1 stimulation significantly increased prostacyclin synthesis in fibroblasts from COPD patients (p < 0.01), but showed no effect on fibroblasts from control subjects. Collagen I synthesis was decreased by iloprost in both control and COPD fibroblasts (p < 0.05). Conversely, iloprost significantly altered biglycan and decorin synthesis in control fibroblasts, but iloprost displayed no effect on these proteoglycans in COPD fibroblasts. Proliferation rate was reduced (p < 0.05) and contractile capacity was increased in COPD fibroblasts (p < 0.05) compared to control fibroblasts. Iloprost decreased proliferative rate in control fibroblasts (p < 0.05), whereas iloprost attenuated contraction capacity in both COPD (p < 0.01) and control fibroblasts (p < 0.05).

CONCLUSIONS

Iloprost reduced collagen I synthesis and fibroblast contractility but did not affect the collagen-associated proteoglycans or proliferation rate in fibroblasts from COPD patients. Enhanced prostacyclin production could lead to improper collagen network fibrillogenesis and a more emphysematous lung structure in severe COPD patients.

Pulmonary hypertension and vascular oxidative damage in cigarette smoke exposed eNOS(-/-) mice and human smokers

CONTEXT

Cigarette smoke is known to be associated with pulmonary hypertension in humans and in animal models. Although the etiology of pulmonary hypertension in smokers is not understood, recent work has suggested a role for inducible nitric oxide synthase (iNOS) in inducing oxidative stress.

OBJECTIVE AND METHODS

To further evaluate this question, we assessed eNOS-/- mice exposed to air or cigarette smoke for the presence of pulmonary hypertension and examined vascular remodeling and expression of nitrotyrosine, a marker of reactive nitrogen species-induced oxidative damage, using immunohistochemistry. To ascertain whether oxidants may play a role in humans, we also examined lung tissue from nonsmokers, and patients with chronic obstructive pulmonary disease (COPD) with and without pulmonary hypertension.

RESULTS

We found that eNOS(-/-) mice developed increased pulmonary arterial pressure after six months cigarette smoke exposure, and this was associated with vascular remodeling and increased vascular nitrotyrosine staining. iNOS gene expression was decreased in the pulmonary arteries of the smoke exposed animals, and no protein was detectable by immunohistochemistry. In humans, vascular nitrotyrosine staining intensity was increased in smokers with COPD compared to nonsmokers, and further increased in smokers with combined COPD and pulmonary hypertension.

CONCLUSIONS

We conclude that cigarette smoke-induced pulmonary hypertension is associated with evidence of oxidative vascular damage by reactive nitrogen species, but that iNOS does not appear to be the major contributor to such damage. Most likely the source of reactive nitrogen species is the cigarette smoke itself.

Phosphodiesterase-4 inhibition improves corticosteroid insensitivity in pulmonary endothelial cells under oxidative stress

BACKGROUND

Several clinical studies have shown that smoking in asthmatics and chronic obstructive pulmonary disease patients is closely associated with corticosteroid refractoriness. In this work, we have analyzed glucocorticoid insensitivity in human pulmonary artery endothelial cells (HPAECs) under cigarette smoke extract (CSE) exposure as well as the possible additive effects of the combination therapy with a phosphodiesterase (PDE)-4 inhibitor.

METHODS

Interleukin (IL)-8 was measured in cell supernatants by ELISA. Histone deacetylase (HDAC), histone acetylase (HAT), and intracellular cAMP levels were measured by colorimetric assays and enzyme immunoassay, respectively. PDE4 isotypes and glucocorticoid receptor (GR)-α and β expression were measured by real-time RT-PCR.

RESULTS

The PDE4 inhibitor rolipram dose dependently inhibited the IL-8 secretion induced by CSE 5%. In contrast, dexamethasone 1 μM did not show inhibitory effect on IL-8 secretion. Combination of subeffective rolipram concentrations at 10 nM increased the inhibitory effect of dexamethasone to ~45% of inhibition. Cigarette smoke extract 5% inhibited HDAC activity and increased HAT activity generating glucocorticoid insensitivity. Rolipram did not modify the HDAC activity, however partially inhibited the increase in HAT activity at 1 μM. PDE4 isotypes were up-regulated by CSE 5% with the consequent cAMP down-regulation. Dexamethasone reduced all PDE4 isotypes expression and showed additive effects with rolipram enhancing cAMP levels. Furthermore, rolipram enhanced GR-α expression and inhibited the increase in GR-β induced by CSE.

CONCLUSIONS

Combination of rolipram and dexamethasone shows additive properties in HPAECs under glucocorticoid insensitive conditions. These results may be of potential value in future anti-inflammatory therapies using combination of PDE4 inhibitors and glucocorticoids.

Mechanics and Mechanisms of Pulmonary Hypertension — Conference Summary and Translational Perspectives

The imagination has made more discoveries than the eye

To catch an imagination of the future of pulmonary hypertension was exactly the spirit of the 55th ASPEN lung Conference. Basic scientists, pre-clinicians, clinicians and pharma joined together to achieve one goal—to combine creativity and inventiveness in a battle against a deadly disease. Summarizing this conference on “Mechanics and Mechanisms of Pulmonary Hypertension” is challenging in several aspects: To extract key novel findings from 12 state-of-the-art lectures, 25 oral presentations, 56 posters along with the integration of own data on discussed topics, to include hundreds of important questions, answers and discussion raised during the conference, to provide the line of thinking for the next 5–10 years of pulmonary hypertension (PH) research development and to focus equally well on both basic and translational research. Kurt Stenmark and Todd Bull, who chaired the conference, intensified this challenge several-fold by selecting a plethora of topics ranging from development of cardiopulmonary systems to pathogenesis of right ventricular failure, mechanics of right ventricle-pulmonary artery coupling to genomics and from understanding metabolic aspects to developing therapies for PH. With that, need not say, but a special admiration and thanks to the conference chairs for assembling such outstanding state-of-the-art speakers, for clustering the presentations logically and for leading lively and engaging discussions. Although it may look fragmentary, we would like to divide the conference summary into four major conceptual realms: The pulmonary vasculature in PH; right heart in PH; individualized approach- personalized medicine; and beyond PH-vascular abnormalities in COPD.

- Joseph Joubert

Pulmonary arterial lesions in explanted lungs after transplantation correlate with severity of pulmonary hypertension in chronic obstructive pulmonary disease

BACKGROUND

Pulmonary vascular findings are largely unreported in end-stage chronic obstructive pulmonary disease (COPD).

METHODS

Pulmonary vascular lesions in explanted lungs from 70 patients with COPD/emphysema or α-1-antitrypsin deficiency were analyzed retrospectively. Patients were stratified by the presence and severity of pulmonary hypertension (PH) assessed by right-heart catheterization in 3 hemodynamically distinct groups: (1) non-PH (mean pulmonary arterial pressure [mPAP]<25 mm Hg), (2) mild to moderate PH (mPAP, 25-34 mm Hg), and (3) severe PH (mPAP≥35 mm Hg). The control group comprised 18 patients with idiopathic pulmonary arterial hypertension (IPAH). Vascular lesions were graded 1-6 according to a modified Heath and Edwards (HE) scale.

RESULTS

All COPD patients were in New York Heart Association Functional Class III-IV (forced expiratory volume in 1 second, 23%±8%; total lung capacity, 128%±20% of predicted). Non-PH group: 30 patients (60% women) aged 54±6 years; mPAP, 17.2±3.8 mm Hg; median HE Grade 1 (range, 0-3), with medial hypertrophy of muscular pulmonary arteries and muscularization of pulmonary arterioles. Mild-moderate PH group: 30 patients (50% women) aged 53±6 years; mPAP, 28.6±2.8 mm Hg; median HE Grade 3 (range, 1-3), with additional cellular intimal proliferation. Severe PH group: 10 patients (50% women) aged 54±6 years; mPAP, 40.7±5.2 mm Hg; median HE Grade 3 (range, 2-5), with additional intimal fibrosis. IPAH controls: 18 patients (67% women) aged 36±4 years; mPAP,>50 mm Hg; median HE Grade 4 (range 3-6), with generalized arterial dilatation and plexiform lesions.

CONCLUSIONS

The extent of pulmonary vascular lesions in COPD correlate with the severity of PH. Morphologic lesions similar to those characteristic of IPAH can be observed as PH in COPD progresses to levels characteristic of IPAH.

Probable Phaeoacremonium parasiticum as a cause of cavitary native lung nodules after single lung transplantation

Lung nodules after lung transplantation most often represent infection or post-transplant lymphoproliferative disorder in the allograft. Conversely, native lung nodules in single lung transplant recipients are more likely to be bronchogenic carcinoma. We present a patient who developed native lung cavitary nodules. Although malignancy was anticipated, evaluation revealed probable Phaeoacremonium parasiticum infection. Phaeoacremonium parasiticum is a dematiaceous fungus first described as a cause of soft tissue infection in a renal transplant patient. Lung nodules have not been previously described and this is the first case, to our knowledge, of P. parasiticum identified after lung transplantation.

Multiple facets of cAMP signalling and physiological impact: cAMP compartmentalization in the lung

Therapies involving elevation of the endogenous suppressor cyclic AMP (cAMP) are currently used in the treatment of several chronic inflammatory disorders, including chronic obstructive pulmonary disease (COPD). Characteristics of COPD are airway obstruction, airway inflammation and airway remodelling, processes encompassed by increased airway smooth muscle mass, epithelial changes, goblet cell and submucosal gland hyperplasia. In addition to inflammatory cells, airway smooth muscle cells and (myo)fibroblasts, epithelial cells underpin a variety of key responses in the airways such as inflammatory cytokine release, airway remodelling, mucus hypersecretion and airway barrier function. Cigarette smoke, being next to environmental pollution the main cause of COPD, is believed to cause epithelial hyperpermeability by disrupting the barrier function. Here we will focus on the most recent progress on compartmentalized signalling by cAMP. In addition to G protein-coupled receptors, adenylyl cyclases, cAMP-specific phospho-diesterases (PDEs) maintain compartmentalized cAMP signalling. Intriguingly, spatially discrete cAMP-sensing signalling complexes seem also to involve distinct members of the A-kinase anchoring (AKAP) superfamily and IQ motif containing GTPase activating protein (IQGAPs). In this review, we will highlight the interaction between cAMP and the epithelial barrier to retain proper lung function and to alleviate COPD symptoms and focus on the possible molecular mechanisms involved in this process. Future studies should include the development of cAMP-sensing multiprotein complex specific disruptors and/or stabilizers to orchestrate cellular functions. Compartmentalized cAMP signalling regulates important cellular processes in the lung and may serve as a therapeutic target.

Pulmonary Hypertension Secondary to COPD

The development of pulmonary hypertension in COPD adversely affects survival and exercise capacity and is associated with an increased risk of severe acute exacerbations. Unfortunately not all patients with COPD who meet criteria for long term oxygen therapy benefit from it. Even in those who benefit from long term oxygen therapy, such therapy may reverse the elevated pulmonary artery pressure but cannot normalize it. Moreover, the recent discovery of the key roles of endothelial dysfunction and inflammation in the pathogenesis of PH provides the rationale for considering specific pulmonary vasodilators that also possess antiproliferative properties and statins.

Current pathophysiological concepts and management of pulmonary hypertension

Pulmonary hypertension (PH), increasingly recognized as a major health burden, remains underdiagnosed due mainly to the unspecific symptoms. Pulmonary arterial hypertension (PAH) has been extensively investigated. Pathophysiological knowledge derives mostly from experimental models. Paradoxically, common non-PAH PH forms remain largely unexplored. Drugs targeting lung vascular tonus became available during the last two decades, notwithstanding the disease progresses in many patients. The aim of this review is to summarize recent advances in epidemiology, pathophysiology and management with particular focus on associated myocardial and systemic compromise and experimental therapeutic possibilities. PAH, currently viewed as a panvasculopathy, is due to a crosstalk between endothelial and smooth muscle cells, inflammatory activation and altered subcellular pathways. Cardiac cachexia and right ventricular compromise are fundamental determinants of PH prognosis. Combined vasodilator therapy is already mainstay for refractory cases, but drugs directed at these new pathophysiological pathways may constitute a significant advance.

IL-18 induces emphysema and airway and vascular remodeling via IFN-γ, IL-17A, and IL-13

RATIONALE

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation, alveolar destruction, and airway and vascular remodeling. However, the mechanisms that lead to these diverse alterations have not been defined.

OBJECTIVES

We hypothesized that IL-18 plays a central role in the pathogenesis of these lesions.

METHODS

We generated and characterized lung-specific, inducible IL-18 transgenic mice.

MEASUREMENTS AND MAIN RESULTS

Here we demonstrate that the expression of IL-18 in the mature murine lung induces inflammation that is associated with the accumulation of CD4(+), CD8(+), CD19(+), and NK1.1(+) cells; emphysema; mucus metaplasia; airway fibrosis; vascular remodeling; and right ventricle cardiac hypertrophy. We also demonstrate that IL-18 induces type 1, type 2, and type 17 cytokines with IFN-γ-inhibiting macrophage, lymphocyte, and eosinophil accumulation while stimulating alveolar destruction and genes associated with cell cytotoxicity and IL-13 and IL-17A inducing mucus metaplasia, airway fibrosis, and vascular remodeling. We also highlight interactions between these responses with IL-18 inducing IL-13 via an IL-17A-dependent mechanism and the type 1 and type17/type 2 responses counterregulating each another.

CONCLUSIONS

These studies define the spectrum of inflammatory, parenchymal, airway, and vascular alterations that are induced by pulmonary IL-18; highlight the similarities between these responses and the lesions in COPD; and define the selective roles that type 1, type 2, and type 17 responses play in the generation of IL-18-induced pathologies.

Dehydroepiandrosterone (DHEA) improves pulmonary hypertension in chronic obstructive pulmonary disease (COPD): a pilot study

OBJECTIVES

It was previously shown that dehydroepiandrosterone (DHEA) reverses chronic hypoxia-induced pulmonary hypertension (PH) in rats, but whether DHEA can improve the clinical and hemodynamic status of patients with PH associated to chronic obstructive pulmonary disease (PH-COPD) has not been studied whereas it is a very severe poorly treated disease.

PATIENTS AND METHODS

Eight patients with PH-COPD were treated with DHEA (200mg daily orally) for 3 months. The primary end-point was the change in the 6-minute walk test (6-MWT) distance. Secondary end-points included pulmonary hemodynamics, lung function tests and tolerance of treatment.

RESULTS

The 6-MWT increased in all cases, from 333m (median [IQR]) (257; 378) to 390m (362; 440) (P<0.05). Mean pulmonary artery pressure decreased from 26mmHg (25; 27) to 21.5mmHg (20; 25) (P<0.05) and pulmonary vascular resistance from 4.2UI (3.5; 4.4) to 2.6UI (2.5; 3.8) (P<0.05). The carbon monoxide diffusing capacity of the lung (DLCO % predicted) increased significantly from 27.4% (20.1; 29.3) to 36.4% (14.6; 39.6) (P<0.05). DHEA treatment did not change respiratory parameters of gas exchange and the 200mg per day of DHEA used was perfectly tolerated with no side effect reported.

CONCLUSION

DHEA treatment significantly improves 6-MWT distance, pulmonary hemodynamics and DLCO of patients with PH-COPD, without worsening gas exchange, as do other pharmacological treatments of PH (trial registration NCT00581087).

Characterization of iodinated adrenomedullin derivatives suitable for lung nuclear medicine

INTRODUCTION

We have recently demonstrated the effectiveness of 99m-technetium adrenomedullin (AM) as a new molecular lung imaging agent that could provide significant advantages for the diagnosis and follow-up of disorders affecting the pulmonary circulation such as pulmonary embolism and pulmonary hypertension. Having the possibility to conjugate the targeting molecule with different radionuclides would offer more flexibility and potential advantages depending on clinical situations. Since various iodine isotopes are currently used in nuclear medicine and in pharmacological studies, we have evaluated which iodination method should be privileged in order to produce a good iodinated AM-derived nuclear medicine agent.

METHODS

Synthetic AM was labeled with iodine through chemical and lactoperoxidase oxidation methods. Position of the iodine atom on the peptide was determined by MALDI-TOF mass spectrometry analysis following cyanogen bromide cleavage and carboxypeptidase Y digestion. Binding affinity of iodinated AM analogues was evaluated by competition and saturation binding experiments on dog lung preparations.

RESULTS

In this study, we demonstrated that, upon lactoperoxidase oxidation, iodination occurred at Tyr(1) and that this radioligand retained higher binding affinity and specificity over preparations obtained through chemical oxidation.

CONCLUSIONS

These results emphasize the fact that even a small chemical modification, i.e. iodination, might deeply modify the pharmacological profile of a compound and support observations that the C-terminal tail of human AM plays an important role in the AM receptor binding process. Consequently, incorporation of a radionuclide to produce an AM-based nuclear medicine agent should privilege the N-terminus of the molecule.

Tobacco-associated pulmonary vascular dysfunction in smokers: role of the ET-1 pathway

Pulmonary vascular remodeling and dysfunction associated to tobacco smoking might pave the way for the subsequent development of pulmonary hypertension. Its prognosis is dreadful and its underlying mechanisms are so far largely unknown in humans. To assess the potential role of endothelin-1 and its receptors in smokers' pulmonary artery vasoactive properties. Endothelium-dependent vasodilation to ACh was assessed in pulmonary vascular rings from 34 smokers and compared with that of 10 nonsmokers. The effects of ET-A (BQ 123) or ET-B (BQ 788) blockers and that of an ET-B activator (sarafotoxin) were evaluated. Endothelin-1 was quantitated by ELISA. Expression of its receptors was quantitated by Western blotting. Smokers exhibited an impaired pulmonary endothelium-dependent vasodilation compared with nonsmokers (P < 0.01). In the former group, 8 of 34 subjects exhibited a marked endothelial dysfunction (ED(+)) whereas 26 (ED(-)) (P < 10(-4)) displayed a vasorelaxation to ACh that was comparable to that of nonsmokers. In ED(+) subjects, ET-A was overexpressed (P < 0.05) and inversely correlated (P < 10(-2)) with the response to ACh. Sarafotoxin significantly improved vasodilation in all subjects (P < 10(-2)). In conclusion, tobacco smoking is associated to an impaired pulmonary vasorelaxation at least partly mediated by an ET-1/ET-A-dependent dysfunction.

Cigarette smoke exposure up-regulates endothelin receptor B in human pulmonary artery endothelial cells: molecular and functional consequences

BACKGROUND AND PURPOSE

Pulmonary arteries from smokers and chronic obstructive pulmonary disease patients show abnormal endothelium-dependent vascular reactivity. We studied the effect of cigarette smoke extract (CSE) on endothelin receptor B (ET(B) ) expression in human pulmonary artery endothelial cells (HPAECs) and its role in endothelial dysfunction.

EXPERIMENTAL APPROACH

ET(B) receptor expression was measured by real time RT-PCR, Western blot and immunofluorescence. Cell contraction, intracellular Ca(2+) , F/G-actin, RhoA activity, myosin light chain phosphorylation, ET, NO, thromboxane (Tx)A(2) and reactive oxygen species (ROS) were measured by traction microscopy, fluorescence microscopy, phalloidin fluorescence, colorimetric assay, Western blot, elisa and DCFDA fluorescence respectively.

KEY RESULTS

Cigarette smoke extract dose-dependently increased ET(B) receptor expression in HPAECs after 24h incubation. CSE-induced ET(B) expression was attenuated by bosentan, the ET(B) receptor antagonist BQ788, the Rho kinase antagonist Y27632 and the antioxidant N-acetylcysteine. A monoclonal antibody to ET-1 prevented CSE-induced ET(B) receptor overexpression. Twenty-four hour exposure to ET-1 dose-dependently increased ET(B) receptor expression, mimicking the effect of CSE. CSE-induced ET(B) receptor overexpression caused greater cell contraction; increased intracellular Ca(2+) ; increased F/G-actin and RhoA activity; increased myosin light chain phosphorylation; augmented TxA(2) and ROS production; and decreased NO after acute ET-1 (10nM). These effects were attenuated by bosentan, BQ788, Y27632 and N-acetylcysteine.

CONCLUSIONS AND IMPLICATION

Cigarette smoke extract induced ET(B) receptor overexpression by a feed forward mechanism mediated partly by ET release, promoting HPAEC dysfunction and attenuated by ET(B) receptor blockade, Rho kinase and ROS inhibition. These results provide support for the use of bosentan in CS-related endothelial dysfunction.

Subcellular and cellular locations of nitric oxide synthase isoforms as determinants of health and disease

The effects of nitric oxide in biological systems depend on its steady-state concentration and where it is being produced. The organ where nitric oxide is produced is relevant, and within the organ, which types of cells are actually contributing to this production seem to play a major determinant of its effect. Subcellular compartmentalization of specific nitric oxide synthase enzymes has been shown to play a major role in health and disease. Pathophysiological conditions affect the cellular expression and localization of nitric oxide synthases, which in turn alter organ cross talk. In this study, we describe the compartmentalization of nitric oxide in organs, cells, and subcellular organelles and how its localization relates to several relevant clinical conditions. Understanding the complexity of the compartmentalization of nitric oxide production and the implications of this compartmentalization in terms of cellular targets and downstream effects will eventually contribute toward the development of better strategies for treating or preventing pathological events associated with the increase, inhibition, or mislocalization of nitric oxide production.

High altitude, a natural research laboratory for the study of cardiovascular physiology and pathophysiology

High altitude constitutes an exciting natural laboratory for medical research. Although initially, the aim of high-altitude research was to understand the adaption of the organism to hypoxia and find treatments for altitude-related diseases, during the past decade or so, the scope of this research has broadened considerably. Two important observations led the foundation for the broadening of the scientific scope of high-altitude research. First, high-altitude pulmonary edema represents a unique model that allows studying fundamental mechanisms of pulmonary hypertension and lung edema in humans. Second, the ambient hypoxia associated with high-altitude exposure facilitates the detection of pulmonary and systemic vascular dysfunction at an early stage. Here, we will review studies that, by capitalizing on these observations, have led to the description of novel mechanisms underpinning lung edema and pulmonary hypertension and to the first direct demonstration of fetal programming of vascular dysfunction in humans.