Carbonic Anhydrase Inhibition Improves Pulmonary Artery Reactivity and Nitric Oxide-Mediated Relaxation in Sugen-Hypoxia Model of Pulmonary Hypertension

2021 ◽  
Author(s):  
Helen Christou ◽  
Zoe Michael ◽  
Fotios Spyropoulos ◽  
Yunfei Chen ◽  
Dan Rong ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Carbonic Anhydrase ◽  
Pulmonary Artery ◽  
Right Ventricular ◽  
Vascular Function ◽  
Systolic Pressure ◽  
Mesenteric Arteries ◽  
Pulmonary Hemodynamics ◽  
Carbonic Anhydrase Inhibition

Pulmonary hypertension (PH) is a serious disease with pulmonary arterial fibrotic remodeling and limited responsiveness to vasodilators. Our data suggest that mild acidosis induced by carbonic anhydrase inhibition could ameliorate PH, but the vascular mechanisms are unclear. We tested the hypothesis that carbonic anhydrase inhibition ameliorates PH by improving pulmonary vascular reactivity and relaxation mechanisms. Male Sprague-Dawley rats were either control normoxic (Nx), or injected with Sugen5416 (20mg/kg, sc) and subjected to hypoxia (9%O2) (Su+Hx), or Su+Hx treated with acetazolamide (ACTZ, 100mg/kg/day, in drinking water). After measuring the hemodynamics, right ventricular hypertrophy was assessed by Fulton's Index; vascular function was measured in pulmonary artery, aorta and mesenteric arteries; and pulmonary arteriolar remodeling was assessed in lung sections. Right ventricular systolic pressure and Fulton's Index were increased in Su+Hx and reduced in Su+Hx+ACTZ rats. Pulmonary artery contraction to KCl and phenylephrine were reduced in Su+Hx and improved in Su+Hx+ACTZ. Acetylcholine (ACh)-induced relaxation and nitrate/nitrite production were reduced in pulmonary artery of Su+Hx and improved in Su+Hx+ACTZ. ACh relaxation was blocked by nitric oxide (NO) synthase and guanylate cyclase inhibitors, supporting a role of NO-cGMP. Sodium nitroprusside (SNP)-induced relaxation was reduced in pulmonary artery of Su+Hx, and ACTZ enhanced relaxation to SNP. Contraction/relaxation were not different in aorta or mesenteric arteries of all groups. Pulmonary arterioles showed wall thickening in Su+Hx that was ameliorated in Su+Hx+ACTZ. Thus, amelioration of pulmonary hemodynamics during carbonic anhydrase inhibition involves improved pulmonary artery reactivity and NO-mediated relaxation, and may enhance responsiveness to vasodilator therapies in PH.

scholarly journals The Endothelial Prolyl-4-Hydroxylase Domain 2/Hypoxia-Inducible Factor 2 Axis Regulates Pulmonary Artery Pressure in Mice

2016 ◽  
Vol 36 (10) ◽  
pp. 1584-1594 ◽  
Author(s):  
Pinelopi P. Kapitsinou ◽  
Ganeshkumar Rajendran ◽  
Lindsay Astleford ◽  
Mark Michael ◽  
Michael P. Schonfeld ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Pulmonary Artery ◽  
Right Ventricular ◽  
Vascular Function ◽  
Oxygen Sensor ◽  
Hypoxia Inducible Factor ◽  
Pulmonary Arteries ◽  
Systolic Pressure ◽  
Ventricular Systolic Pressure ◽  
Apelin Receptor

Hypoxia-inducible factors 1 and 2 (HIF-1 and -2) control oxygen supply to tissues by regulating erythropoiesis, angiogenesis and vascular homeostasis. HIFs are regulated in response to oxygen availability by prolyl-4-hydroxylase domain (PHD) proteins, with PHD2 being the main oxygen sensor that controls HIF activity under normoxia. In this study, we used a genetic approach to investigate the endothelial PHD2/HIF axis in the regulation of vascular function. We found that inactivation ofPhd2in endothelial cells specifically resulted in severe pulmonary hypertension (∼118% increase in right ventricular systolic pressure) but not polycythemia and was associated with abnormal muscularization of peripheral pulmonary arteries and right ventricular hypertrophy. Concurrent inactivation of eitherHif1aorHif2ain endothelial cell-specificPhd2mutants demonstrated that the development of pulmonary hypertension was dependent on HIF-2α but not HIF-1α. Furthermore, endothelial HIF-2α was required for the development of increased pulmonary artery pressures in a model of pulmonary hypertension induced by chronic hypoxia. We propose that these HIF-2-dependent effects are partially due to increased expression of vasoconstrictor molecule endothelin 1 and a concomitant decrease in vasodilatory apelin receptor signaling. Taken together, our data identify endothelial HIF-2 as a key transcription factor in the pathogenesis of pulmonary hypertension.

Sildenafil therapy for neonatal and childhood pulmonary hypertensive vascular disease

2010 ◽  
Vol 21 (2) ◽  
pp. 187-193 ◽  
Author(s):  
Tilman Humpl ◽  
Janette T. Reyes ◽  
Simon Erickson ◽  
Ruth Armano ◽  
Helen Holtby ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Pulmonary Artery ◽  
Right Ventricular ◽  
Pressure Ratio ◽  
Systolic Pressure ◽  
Resistance Index ◽  
Pulmonary Artery Hypertension ◽  
Inhaled Nitric Oxide ◽  
Drug Study

AbstractObjectivesWe hypothesised that sildenafil would improve hemodynamics in children with pulmonary hypertension and attenuate rebound pulmonary hypertension after inhaled nitric oxide withdrawal.Patients and methodsWe undertook an open-label, single-drug study of sildenafil in patients under 5 years of age with either symptomatic or rebound pulmonary hypertension following inhaled nitric oxide withdrawal.ResultsWe recruited 25 patients (median age 180 days, 10–1790) to receive sildenafil. The median right ventricular to systemic systolic blood pressure ratio before sildenafil therapy was 1.0 (0.5–1.4) and decreased to 0.5 (with a range from 0.3 to 1.3; p = 0.0002). In five patients the baseline pulmonary vascular resistance index was 10 (7.1–13.6) Wood units metre square and decreased to 5.8 (2.7–15.6) Wood units metre square (p = 0.04) at 6 months. Ten patients were treated with sildenafil for a median of 34 days (9–499) until resolution of pulmonary artery hypertension and continue to do well. Six patients continued sildenafil therapy for a median of 1002 days (384–1574) with improvement but without resolution of pulmonary hypertension. There was no change in serum creatinine, urea, liver function tests, or platelet count. In 15 patients sildenafil abolished rebound pulmonary artery hypertension following withdrawal of inhaled nitric oxide. Median right ventricular pressure to systemic systolic pressure ratio decreased from 1.0 (0.8–1.4) during nitric oxide withdrawal to 0.4 (0.3–0.8) p = 0.006 after pre-treatment with sildenafil.ConclusionIn children under 5 years of age with severe pulmonary hypertension, sildenafil therapy resulted in prolonged hemodynamic improvements without adverse effects. Sildenafil attenuated rebound pulmonary hypertension after withdrawal of inhaled nitric oxide.

TSP1-CD47 Signaling Modulates the Severity of Pulmonary Hypertension in a Mouse Model of Sickle Cell Disease

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 898-898
Author(s):  
Enrico M Novelli ◽  
Mingyi Yao ◽  
Xiaojun Huang ◽  
Jeffrey Baust ◽  
Hunter Champion ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Sickle Cell Disease ◽  
Right Ventricle ◽  
Right Ventricular ◽  
Sickle Cell ◽  
Systolic Pressure ◽  
Cell Disease ◽  
C57bl Mice ◽  
No Signaling

Abstract Abstract 898 In sickle cell disease (SCD), mutant hemoglobin S polymerizes when deoxygenated, driving red blood cell (RBC)-dependent vaso-occlusion and hemolysis. These processes lead to platelet and hemostatic activation, pulmonary hypertension (PH) and vascular disease. Transgenic-knockout sickle (BERK) mice that express exclusively human α- and βS-globins mimic SCD in humans by displaying reduced nitric oxide (NO) bioavailability, impaired NO-mediated vascular reactivity and PH. Recently, the platelet α-granule protein thrombospondin-1 (TSP1) was found to be elevated in the plasma of patients with SCD and to potently inhibit physiologic NO signaling, via binding to the cell surface receptor CD47. We hypothesized that blocking the TSP1-CD47 interaction may restore NO signaling and prevent PH in BERK mice. To test this hypothesis we conducted a transplantation experiment to explore the repopulating potential of BERK bone marrow (BM) in lethally myeloablated CD47KO recipients and the impact of the CD47 null milieu on the PH phenotype. We harvested the BM from 5–6 months old BERK mice and transplanted it into irradiated (10 Gy) 8–9 weeks old CD47KO mice (n=9). All recipients survived transplantation and were terminally evaluated 4 months post transplantation. Mice underwent blood sampling for determination of engraftment by hemoglobin electrophoresis, evaluation of endothelial dependent arterial vasodilation by myography, full pulmonary hemodynamic assessment and measurement of right ventricular hypertrophy (RVH) using the Fulton Index (ratio of ventricular weights (right ventricle/left ventricle including septum). The chimeras had 98.3% (SD 0.6%) hemoglobin S, thereby demonstrating full donor chimerism. Segments of thoracic aortas from the chimeras were mounted on a myograph system and exposed to acetylcholine, a physiologic vasodilator that stimulates endothelial nitric oxide synthase (eNOS) activation. Concentration-response curves showed that the arterial segments from chimeras that lacked tissue CD47 had improved endothelial-dependent vasodilation, as evaluated by % relaxation in response to acetylcholine, as compared to arterial segments from BERK mice (P < 0.05). Hemodynamic data showed that the tissue CD47KO chimeras had lower right ventricular end systolic pressure (RV ESP) as compared to BERK mice (22 vs. 31 mm Hg, p<0.05). Conversely, their RV ESP did not significantly differ from historical control C57BL/6 mice (22 vs. 20 mm Hg, NS, panel A). Measurement of RVH (Fulton Index) similarly revealed that the chimeras were protected from RVH (p<0.05, panel B). Thus, despite the presence of sickle RBC, the absence of the TSP1-CD47 signaling axis improved endothelial-eNOS-NO signaling and reduced pulmonary pressures and RVH responses. These data demonstrate that BM from BERK mice successfully engrafts CD47KO mice, and that in the absence of the TSP1-CD47 axis endothelial and vascular function improves and PH is ameliorated. We now plan to validate these results in controlled experiments where BM from BERK mice is transplanted in CD47KO and C57BL mice as controls. We expect that unlike C57BL mice transplanted with BERK BM, CD47KO mice will be protected from the vascular complications of SCD, including PH.Figurelegend: CD47KO mice transplanted with BERK BM (chimeras) show improved hemodynamics (Panel A) and less right ventricular (RV) hypertrophy as measured by the Fulton Index as compared to BERK mice (Panel B). * = statistically significant, NS = non significant, RV ESP = right ventricle end systolic pressure.Figure. legend: CD47KO mice transplanted with BERK BM (chimeras) show improved hemodynamics (Panel A) and less right ventricular (RV) hypertrophy as measured by the Fulton Index as compared to BERK mice (Panel B). * = statistically significant, NS = non significant, RV ESP = right ventricle end systolic pressure. Disclosures: Isenberg: Vasculox, Inc.: Equity Ownership.

scholarly journals Novel Pyrazolo[3,4-b] Pyridine Derivative (HLQ2g) Attenuates Hypoxic Pulmonary Hypertension via Restoring cGKI Expression and BMP Signaling Pathway

2021 ◽  
Vol 12 ◽  
Author(s):  
Lijun Li ◽  
Minghui Yin ◽  
Liqing Hu ◽  
Xiaoting Tian ◽  
Xiangrong He ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Pulmonary Artery ◽  
Right Ventricular ◽  
Signaling Pathway ◽  
Systolic Pressure ◽  
Bmp Signaling ◽  
Pyridine Derivative ◽  
Type I ◽  
And Migration ◽  
Proliferation And Migration

Pulmonary hypertension (PH) is an extremely serious cardiopulmonary disease, finally leading to progressive right ventricular failure and death. Our previous studies have nominated HLQ2g, a pyrazolo[3,4-b] pyridine derivative stimulating soluble guanylate cyclase (sGC), as a new candidate for the treatment of PH, but the specific mechanism is still not clear. The PH model induced by hypoxia was established in rats. Right ventricular systolic pressure (RVSP) was assessed by jugular vein catheterization. RV weight was the index to evaluate RV hypertrophy. The protein levels of cGMP-dependent protein kinase type I (cGKI), bone morphogenetic protein receptor 2 (BMPR2), phosphorylated Smad1/5/8 (p-Smad1/5/8), and inhibitor of differention 1 (Id1) in pulmonary artery and human pulmonary artery smooth muscle cells (HPASMCs) were determined by western blotting. Cell proliferation and migration were evaluated. In the whole experiment, the first clinically available sGC stimulator Riociguat was used as the reference. In hypoxic PH rat model, elevated RVSP and RV hypertrophy were significantly reduced by HLQ2g treatment. Both Riociguat and HLQ2g attenuated vascular remodeling accompanied with up-regulated cGKI expression and BMP signaling pathway, which was characterized by elevated expression of BMPR2, p-Smad1/5/8, and Id1 in HPH rats. In addition, HLQ2g inhibited proliferation and migration of HPASMCs induced by hypoxia and platelet-derived growth factor (PDGF), restored BMPR2 signaling, which was recalled by Rp-8-Br-PET-cGMPS, the inhibitor of cGKI. In summary, the novel pyrazolo[3,4-b] pyridine derivative HLQ2g can alleviate HPH progression by up-regulating cGKI protein and BMP signaling pathway.

scholarly journals Right ventricular myocardial oxygen tension is reduced in monocrotaline-induced pulmonary hypertension in the rat and restored by myo-inositol trispyrophosphate

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marta Oknińska ◽  
Zuzanna Zambrowska ◽  
Karolina Zajda ◽  
Aleksandra Paterek ◽  
Klaudia Brodaczewska ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Pulmonary Artery ◽  
Right Ventricular ◽  
Oxygen Tension ◽  
Systolic Pressure ◽  
Wall Stress ◽  
Saline Control ◽  
Oxygen Balance ◽  
Important Target ◽  
Oxygen Dissociation

AbstractPulmonary hypertension (PH) initially results in compensatory right ventricular (RV) hypertrophy, but eventually in RV failure. This transition is poorly understood, but may be triggered by hypoxia. Measurements of RV oxygen tension (pO2) in PH are lacking. We hypothesized that RV hypoxia occurs in monocrotaline-induced PH in rats and that myo-inositol trispyrophosphate (ITPP), facilitating oxygen dissociation from hemoglobin, can relieve it. Rats received monocrotaline (PH) or saline (control) and 24 days later echocardiograms, pressure–volume loops were obtained and myocardial pO2 was measured using a fluorescent probe. In PH mean pulmonary artery pressure more than doubled (35 ± 5 vs. 15 ± 2 in control), RV was hypertrophied, though its contractility was augmented. RV and LV pO2 was 32 ± 5 and 15 ± 8 mmHg, respectively, in control rats. In PH RV pO2 was reduced to 18 ± 9 mmHg, while LV pO2 was unchanged. RV pO2 correlated with RV diastolic wall stress (negatively) and LV systolic pressure (positively). Acute ITPP administration did not affect RV or LV pO2 in control animals, but increased RV pO2 to 26 ± 5 mmHg without affecting LV pO2 in PH. RV oxygen balance is impaired in PH and as such can be an important target for PH therapy. ITPP may be one of such potential therapies.

scholarly journals PKG-1α leucine zipper domain defect increases pulmonary vascular tone: implications in hypoxic pulmonary hypertension

2014 ◽  
Vol 307 (7) ◽  
pp. L537-L544 ◽  
Author(s):  
Ramaswamy Ramchandran ◽  
Aarti Raghavan ◽  
David Geenen ◽  
Miranda Sun ◽  
Laura Bach ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Right Ventricular ◽  
Vascular Tone ◽  
Leucine Zipper ◽  
Ventricular Remodeling ◽  
Systolic Pressure ◽  
Progressive Increase ◽  
Leucine Zipper Domain ◽  
Phosphodiesterase 5

Pulmonary hypertension (PH) is a chronic disease characterized by a progressive increase in vasomotor tone, narrowing of the vasculature with structural remodeling, and increase in pulmonary vascular resistance. Current treatment strategies include nitric oxide therapy and methods to increase cGMP-mediated vasodilatation. cGMP-dependent protein kinases (PKG) are known mediators of nitric oxide- and cGMP-induced vasodilatation. Deletion of PKG-1 in mice has been shown to induce PH, however, the exact mechanisms by which loss of PKG-1 function leads to PH is not known. In a mouse model with a selective mutation in the NH2-terminus leucine zipper protein interaction domain of PKG-1α [leucine zipper mutant (LZM)], we found a progressive increase in right ventricular systolic pressure and right heart hypertrophy compared with wild-type (WT) mice and increased RhoA-GTPase activity in the lungs. When exposed to chronic hypoxia, LZM mice developed modestly enhanced right ventricular remodeling compared with WT mice. Tadalafil, a phosphodiesterase-5 inhibitor that increases cGMP levels, significantly attenuated hypoxia-induced cardiopulmonary remodeling in WT mice but had no effect in LZM mice. We conclude that a functional leucine zipper domain in PKG-1α is essential for maintenance of a low pulmonary vascular tone in normoxia and for cGMP-mediated beneficial effects of phosphodiesterase-5 inhibition in hypoxic cardiopulmonary remodeling.

scholarly journals Maternal omega-3 PUFA supplementation prevents hyperoxia-induced pulmonary hypertension in the offspring

2018 ◽  
Vol 315 (1) ◽  
pp. L116-L132 ◽  
Author(s):  
Ying Zhong ◽  
Daniel Catheline ◽  
Ali Houeijeh ◽  
Dyuti Sharma ◽  
Lizhong Du ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Right Ventricular ◽  
Lung Tissue ◽  
Vascular Remodeling ◽  
Systolic Pressure ◽  
Vascular Density ◽  
Vegf Receptor ◽  
Omega 3 ◽  
Pufa Supplementation

Pulmonary hypertension (PH) and right ventricular hypertrophy (RVH) affect 16–25% of premature infants with bronchopulmonary dysplasia (BPD), contributing significantly to perinatal morbidity and mortality. Omega-3 polyunsaturated fatty acids (PUFA ω-3) can improve vascular remodeling, angiogenesis, and inflammation under pathophysiological conditions. However, the effects of PUFA ω-3 supplementation in BPD-associated PH are unknown. The present study aimed to evaluate the effects of PUFA ω-3 on pulmonary vascular remodeling, angiogenesis, and inflammatory response in a hyperoxia-induced rat model of PH. From embryonic day 15, pregnant Sprague-Dawley rats were supplemented daily with PUFA ω-3, PUFA ω-6, or normal saline (0.2 ml/day). After birth, pups were pooled, assigned as 12 per litter, randomly assigned to either air or continuous oxygen exposure (fraction of inspired oxygen = 85%) for 20 days, and then euthanized for pulmonary hemodynamic and morphometric analysis. We found that PUFA ω-3 supplementation improved survival, decreased right ventricular systolic pressure and RVH caused by hyperoxia, and significantly improved alveolarization, vascular remodeling, and vascular density. PUFA ω-3 supplementation produced a higher level of total ω-3 in lung tissue and breast milk and was found to reverse the reduced levels of VEGFA, VEGF receptor 2, angiopoietin-1 (ANGPT1), endothelial TEK tyrosine kinase, endothelial nitric oxide synthase, and nitric oxide concentrations in lung tissue and the increased ANGPT2 levels in hyperoxia-exposed rats. The beneficial effects of PUFA ω-3 in improving lung injuries were also associated with an inhibition of leukocyte infiltration and reduced expression of the proinflammatory cytokines IL-1β, IL-6, and TNF-α. These data indicate that maternal PUFA ω-3 supplementation strategies could effectively protect against infant PH induced by hyperoxia.

scholarly journals Parathyroid hormone affects right heart hemodynamics and exacerbates pulmonary hypertension

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
Y J Joki ◽  
H K Konishi ◽  
K T Takasu ◽  
T M Minamino
Keyword(s):  
Pulmonary Hypertension ◽  
Parathyroid Hormone ◽  
Pulmonary Artery ◽  
Right Ventricular ◽  
Pulmonary Artery Pressure ◽  
Ventricular Hypertrophy ◽  
Right Ventricular Hypertrophy ◽  
Right Heart ◽  
Pulmonary Hemodynamics ◽  
Artery Pressure

Abstract Background Pulmonary hypertension (PH) is characterized by increased pulmonary artery pressure and develops right heart failure. Parathyroid hormone (PTH) is secreted from parathyroid gland and regulates a calcium homeostasis. Recent studies have suggested that PTH also acts on the cardiovascular system and affects cardiovascular prognosis. We hypothesized that PTH would play a role in the pathogenesis of PH. Purpose This study aimed to investigate the effect of PTH on pulmonary hemodynamics. Method We measured serum PTH levels in patients who were suspected of PH and underwent right heart catheter examination. We used two types of PH animal models, hypoxia (Hx)-induced PH mouse model and Sugen/hypoxia (SuHx)-induced PH rat model. Hx mice were administered PTH daily for 3 weeks. SuHx rats underwent parathyroidectomy, after which they received SuHx treatment for 10weeks. We measured physical data and right ventricular systolic pressure (RVSP) in these models. We cultured pulmonary artery smooth muscle cell (PASMC) treated with PTH to analyze cell signaling, proliferation and migration. Result We enrolled 20 participants. PTH concentration was significantly correlated with mean pulmonary artery pressure (r=0.58, p=0.006) as well as with pulmonary vascular resistance (r=0.61, p=0.04). Receiver operating characteristic curve displayed a cut-off PTH level of 48.0pg/ml that offered optimal differentiation between patients with and without PH (100% sensitivity, 73% specificity). PTH treatment exacerbated right ventricular hypertrophy and increased RVSP (33.6mmHg vs. 48.2mmHg) in Hx mice compared with non-treated Hx mice (Figure 1). Conversely, parathyroidectomy significantly attenuated right ventricular hypertrophy and reduced RVSP (54.2mmHg vs. 29.3mmHg) in SuHx rats compared with sham-operated SuHx rats. PTH promoted migration and proliferation through ERK signaling in PASMC. Conclusion Our clinical and experimental data demonstrated a critical role of PTH in the development of PH and suggested that PTH would be a novel therapeutic target for PH treatment. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Grant-in-Aid for Young Scientists Figure 1. PTH treatment exacerbated RVSP

scholarly journals CREB depletion in smooth muscle cells promotes medial thickening, adventitial fibrosis and elicits pulmonary hypertension

2020 ◽  
Vol 10 (2) ◽  
pp. 204589401989837 ◽  
Author(s):  
Chrystelle V. Garat ◽  
Susan M. Majka ◽  
Timothy M. Sullivan ◽  
Joseph T. Crossno ◽  
Jane E.B. Reusch ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Smooth Muscle ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Right Ventricular ◽  
Chronic Hypoxia ◽  
Pulmonary Arteries ◽  
Systolic Pressure ◽  
Muscle Cells

Levels of the cAMP-responsive transcription factor, CREB, are reduced in medial smooth muscle cells in remodeled pulmonary arteries from hypertensive calves and rats with chronic hypoxia-induced pulmonary hypertension. Here, we show that chronic hypoxia fails to promote CREB depletion in pulmonary artery smooth muscle cells or elicit significant remodeling of the pulmonary arteries in mice, suggesting that sustained CREB expression prevents hypoxia-induced pulmonary artery remodeling. This hypothesis was tested by generating mice, in which CREB was ablated in smooth muscle cells. Loss of CREB in smooth muscle cells stimulated pulmonary artery thickening, right ventricular hypertrophy, profound adventitial collagen deposition, recruitment of myeloid cells to the adventitia, and elevated right ventricular systolic pressure without exposure to chronic hypoxia. Isolated murine CREB-null smooth muscle cells exhibited serum-independent proliferation and hypertrophy in vitro and medium conditioned by CREB-null smooth muscle cells stimulated proliferation and expression of extracellular matrix proteins by adventitial fibroblasts. We conclude that CREB governs the pathologic switch from homeostatic, quiescent smooth muscle cells to proliferative, synthetic cells that drive arterial remodeling contributing to the development or pulmonary hypertension.

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