Remodeling Of Pulmonary Arterioles Research Articles

Immunotherapy of Endothelin-1 Receptor Type A for Pulmonary Arterial Hypertension

BackgroundPulmonary arterial hypertension (PAH) is a chronic fatal disease. The treatment of PAH is less than ideal and the control is far from satisfactory worldwide. Vaccination provides a promising approach for treatment of PAH. ObjectivesThis study sought to find a vaccine against endothelin-1 (ET-1) receptor type A (ETAR) for treating PAH. MethodsThe ETRQβ-002 vaccine was screened and the specific antibodies against epitope ETR-002 belonging to the second extracellular loop of ETAR (including the polyclonal and monoclonal antibody) were produced. The effect of the antibodies on Ca2+-dependent signal transduction events was investigated. In vivo, ETRQβ-002 vaccine was used to vaccinate monocrotaline (MCT)- and Sugen/hypoxia–induced pulmonary hypertension animals. The monoclonal antibody (mAb) against ETR-002 was also injected into the PAH animals. The effect of ETRQβ-002 vaccine on pulmonary hypertension and remodeling of pulmonary arterioles and right ventricle (RV) was carefully evaluated. Further, the possible immune-mediated damage was detected in normal vaccinated animals. ResultsETR-002 peptide has perfect immunogenicity and ETRQβ-002 vaccine could induce strong antibody production. In vitro, the anti–ETR-002 antibody bound to ETAR and inhibited Ca2+-dependent signal transduction events, including extracellular signal-regulated kinase phosphorylation and elevation of intracellular Ca2+ concentration induced by ET-1. In vivo, both ETRQβ-002 vaccine and the mAb significantly decreased the RV systolic pressure up to 20 mm Hg and 10 mm Hg in MCT-exposed rats and Sugen/hypoxia–exposed mice, respectively. Also, ETRQβ-002 vaccine/mAb obviously ameliorated pathological remodeling of pulmonary arterioles and hypertrophy of the RV in PAH animals. Additionally, no significant immune-mediated damage was detected in vaccinated animals. ConclusionsETRQβ-002 vaccine/mAb attenuated remodeling of pulmonary arterioles and RV in MCT- and Sugen/hypoxia–induced PAH animals and decreased RV systolic pressure effectively through diminishing the pressure response and inhibiting signal transduction initiated by ET-1. ETRQβ-002 vaccine/mAb may provide a novel and promising method for PAH treatment.

Inhibition of miR-495 Improves Both Vascular Remodeling and Angiogenesis in Pulmonary Hypertension

Background and Aims: Pulmonary hypertension (PH) is a chronic progressing vascular disease characterized by pulmonary arteriole remodeling and loss of pulmonary microvasculature. The aim of this study was to investigate a potential role for the miR-495 in PH pathogenesis and to explore its therapeutic potential in PH. Methods: Male C57BL/6J mice were injected with SU5416 weekly during 3 weeks of exposure to 10% oxygen to cause PH. We first tested the effects of adeno-associated virus 9 (AAV9) delivery which was specifically designed to block miR-495 in the lungs of the PH model. Then, the biological function of miR-495 was analyzed in cultured pulmonary arterial endothelial cells (PAECs) under hypoxic condition. Results: The inhibition of miR-495 improves hemodynamics and vascular remodeling in PH. At the same time, these effects were associated with increases in angiogenic transcription factor VEZF1 and marked upregulation of other angiogenic genes such as Angpt-1 and IGF1. In vitro, cultured mouse PAECs were transfected with miR-495 inhibitor or miR-495 mimics. Both the flow cytometry results and CCK8 assay showed that miR-495 inhibitor increased the percentage of cells in the G2/M+S phase, and the wound healing assays indicated that the migration capacity of PAECs transfected with miR-495 inhibitor was increased compared to the inhibitor-NC cells. Conclusions: Our results indicate that AAV9-TuD-miR-495 delivery improves hemodynamic and pulmonary vascular structural changes in PH mice.

Reverse Remodeling of Pulmonary Arterioles After Pulmonary Artery Banding in Patients ≥ 2 Years Old with Severe Pulmonary ArterialHypertension and Congenital Heart Disease.

The purpose of this study was to evaluate the pathological changes of the pulmonary arterioles in patients ≥ 2 years of age who first underwent a pulmonary artery banding (PAB) procedure, followed by bidirectional Glenn or Fontan according to their specific conditions. This was a prospective study of 15 children diagnosed and treated with PAB at the Department of Cardiothoracic Surgery of Anzhen Hospital between January 2009 and December 2012. The percentage of media area (%MS) of pulmonary arteriole, the percentage of media thickness (%MT), and pulmonary arterial density (APSC) were calculated from lung tissue sections. Pulmonary artery pressure decreased significantly after PAB surgery (P < 0.01). Postoperative mean pulmonary artery pressure declined significantly (P < 0.01), the cardiothoracic ratio was reduced (P < 0.05), and percutaneous oxygen saturation (inhaled air) decreased to 80-85% (P < 0.01). %MT (from 35.1 ± 5.6% to 26.9 ± 4.3%, P < 0.01), %MS (from 51.4 ± 6.7% to 32.2 ± 7.4%, P < 0.01), and APSC (from 108.3 ± 38.5 to 83.6 ± 19.6, P < 0.01) were decreased significantly after PAB. Five patients underwent the bidirectional Glenn procedure and four underwent Fontan. In conclusion, the results suggest that PAB can reduce pulmonary artery pressure and that pulmonary arterial lesions can be reversed after PAB.

Lung Hydrogel Implantation System to Study the Pathogenesis of Pulmonary Hypertension

Remodeling of distal pulmonary arterioles (PAs) associated with marked accumulation of pulmonary artery smooth muscle cells (PASMCs) represents one of the major pathologic features of pulmonary hypertension (PH). The levels of a transcription factor, Twist1 are upregulated in the lungs of patients with pulmonary arterial hypertension (PAH). However, the mechanism by which endothelial Twist1 stimulates SMC accumulation to distal PAs in PH remains unclear. Here we have found that Twist1 overexpression increases the expression of platelet‐derived growth factor (PDGFB) in cultured human pulmonary arterial endothelial cells (HPAECs). Conditioned media collected from Twist1 overexpressing HPAECs induce SMC migration and growth. Knockdown of Twist1 in ECs attenuates hypoxia‐induced accumulation of alpha‐smooth muscle actin (SMA)‐positive cells to the PAs in mice. To further study the mechanism by which endothelial Twist1 controls vascular remodeling and SMC accumulation in the lung, we implant fibrin gel supplemented with fluorescently labeled HPAECs on the mouse lung. Supplemented HPAECs form vascular structures and hypoxia treatment stimulates accumulation of alpha‐SMA–positive cells to blood vessels and upregulates expression of PDGFB in the gel. Twist1 overexpression in supplemented HPAECs or hypoxia treatment also induces endothelial‐to‐mesenchymal transition (EndMT) in the implanted gel, which also partly contributes to the pathogenesis of PH. Endothelial Twist1 plays a key role in SMC accumulation to PAs through PDGFB signaling and the mouse lung gel implantation system would be a good model system to study the pathogenesis of PH and other lung diseases.Support or Funding InformationAHA18TPA34170129, MCW Research Affair Committee New Investigator AwardThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Activation of Nicotinic Acetylcholine α7 Receptor Attenuates Progression of Monocrotaline-Induced Pulmonary Hypertension in Rats by Downregulating the NLRP3 Inflammasome.

Background: Inflammation and altered immunity contribute to the development of pulmonary arterial hypertension (PH). The alpha 7 nicotinic acetylcholine receptor (α7nAChR) possesses anti-inflammatory activities. The current study was performed to investigate the effects of a selective α7nAChR agonist, PNU-282987, on controlling a monocrotaline (MCT)-induced rat model of PH and explored the underlying mechanisms.Methods: Sprague-Dawley rats were injected with MCT and treated with PNU-282987 at the prevention (starting 1 week before MCT) and treatment (starting 2 weeks after MCT) settings. Four weeks after MCT injection, hemodynamic changes, right ventricular structure, and lung morphological features were assessed. Enzyme-linked immunosorbent assay, Western blot and qRT-PCR were performed to assess levels of inflammatory cytokines and NLRP3 (Nod-like receptor family pyrin domain-containing 3) inflammasome pathway in the rat lung tissues. In addition, the lung macrophage line NR8383 was used to confirm the in vivo data.Results: Monocrotaline injection produced PH in rats and downregulated α7nAChR mRNA and protein expression in rat lung tissues compared to sham controls. Pharmacological activation of α7nAChR by PNU-282987 therapy improved the rat survival rate, attenuated the development of PH as assessed by remodeling of pulmonary arterioles, reduced the right ventricular (RV) systolic pressure, and ameliorated the hypertrophy and fibrosis of the RV in rats with MCT-induced PH. The expression of TNF-α, IL-6, IL-1β, and IL-18 were downregulated in rat lung tissues, which implied that PNU-282987 therapy may help regulate inflammation. These protective effects involved the inhibition of the NLRP3 inflammasome. In vitro assays of cultured rat lung macrophages confirmed that the anti-inflammation effect of PNU-282987 therapy may contribute to the disturbance of NLRP3 inflammasome activation.Conclusion: Targeting α7nAChR with PNU-282987 could effectively prevent and treat PH with benefits for preventing ongoing inflammation in the lungs of rats with MCT-induced PH by inhibiting NLRP3 inflammasome activation.

The effect of bone marrow mesenchymal stem cell transplantation on hypoxic pulmonary hypertension in rats

Objective: To study the influence of bone marrow mesenchymal stem cells (MSCs) transplantation on hypoxic pulmonary hypertension (HPH) in rats. Methods: MSCs in SD rats were separated, cultivated, identified in vitro, and labeled by the green fluorescence protein (GFP) adenovirus. Healthy male SD rats were randomly divided into four groups: normal control group (NC group) and HPH group, with eight rats in each group respectively; HPH + mesenchymal stem cell transplantation group (MSCs group) and HPH + vascular endothelial growth factor + mesenchymal stem cell transplantation group (VEGF + MSCs group), with twenty-four rats in each group respectively. In this experiment, intermittent normobaric hypoxia was employed to establish the pulmonary hypertension rat models, with stem cells transfected and transplanted. The mean pulmonary artery pressure (mPAP) was observed in rats to calculate the right ventricular hypertrophy index (RVHI); the morphological changes of pulmonary arterioles in each group of rats were observed under the microscope; the distribution and manifestation of MSCs fluorescently labeled by adenovirus transfection were observed in pulmonary arterioles under the fluorescence microscope at the set time points of 7 d, 14 d and 28 d after the transplantation of stem cells. Results: For NC group, the mPAP (mmHg) was 15.5 ± 1.5 at 28 d, while the mPAP in HPH, MSCs and VEGF + MSCs groups were 26.1 ± 1.9, 21.6 ± 2.7 and 20.1 ± 2.9 respectively which were apparently higher than that in NC group ( p < .01). Compared with HPH group ( p < .01), the mPAP was obviously decreased in MSCs and VEGF + MSCs groups. There was no significant difference between MSCs and VEGF + MSCs groups. At 28 d, RVHI for NC group was 0.28 ± 0.02, while the RVHI in HPH, MSCs and VEGF + MSCs groups were 0.43 ± 0.07, 0.34 ± 0.03 and 0.35 ± 0.01 respectively which were apparently higher than that in NC group ( p < .01). In comparison with HPH group, RVHI was significantly decreased in MSCs and VEGF + MSCs groups ( p < .05). There was no significant difference between MSCs and VEGF + MSCs groups. For HPH group, at 28 d, pulmonary arterioles were apparently thickened, with luminal stenosis & obliteration and incomplete endothelial cells. Compared with HPH group, pulmonary arterioles in MSCs group became thinning, with the lumen unobstructed and the integrity of endothelial cells improved. The changes in the manifestation of MSCs and VEGF + MSCs groups were not significant. Conclusions: The transplantation of MSCs can improve the remodeling of pulmonary arterioles to partially reverse the progress of HPH; the combined transplantation of VEGF and MSCs doesn’t improve the effect of MSC transplantation.

Tsantan Sumtang Alleviates Chronic Hypoxia-Induced Pulmonary Hypertension by Inhibiting Proliferation of Pulmonary Vascular Cells.

Hypoxia-induced pulmonary hypertension (HPH) is a severe condition associated with significant morbidity and mortality in people living at high altitude. Tsantan Sumtang, a traditional Tibetan medicine, has been routinely used for the treatment of cardiopyretic disease, as well as stenocardia. Interestingly, our previous research found that Tsantan Sumtang improved HPH in rats maintaining in a hypobaric chamber. We performed a series of experiments to test the indexes of vasoconstriction and vascular remodeling, the key pathophysiological characteristics of HPH. Our results showed that Tsantan Sumtang relaxed noradrenaline (NE)-precontracted rat pulmonary artery rings in a concentration-dependent manner in vitro. The PGI2-cAMP (prostaglandin I2-cyclic adenosine monophosphate) pathway, NO-cGMP (nitric oxide-cyclic guanosine monophosphate) pathway, and the opening of K+ channels (inward rectifier K+ channels, large conductance Ca2+-activated K+ channels, and voltage-dependent K+ channels) might play major roles in the vasorelaxation effect. In vivo, the administration of Tsantan Sumtang resulted in a substantial decrease in the rat mean pulmonary artery pressure (mPAP) and the right ventricular hypertrophy index (RVHI). The reduction of thickness of small pulmonary arterial wall and the WT% (the ratio of the vascular wall thickness to the vascular diameter) were observed. The smooth muscle muscularization of the arterials was alleviated by Tsantan Sumtang treatment at the same time. Tsantan Sumtang also reduced remodeling of pulmonary arterioles by suppressing the expression of proliferating cell nuclear antigen (PCNA), α-smooth muscle actin (α-SMA), cyclin D1, and cyclin-dependent kinase 4 (CDK4) through inhibition of p27Kip1 degradation. Therefore, Tsantan Sumtang could be applied as a preventative medication for HPH, which would be a new use for this traditional medicine.

5-HT promotes pulmonary arterial smooth muscle cell proliferation through the TRPC channel

Pulmonary arterial hypertension is caused by an imbalance of pulmonary vasoconstriction and vasodilation. Pulmonary arteriolar remodeling is a primary pathological change and proliferation of pulmonary arterial smooth muscle cells (PASMC) is an important pathological basis for pulmonary arteriolar remodeling. Vasoactive substances, such as 5-HT, may play a role in proliferation of PASMC via unknown mechanisms. In vitro experiments with PASMC showed that the TRPC channel inhibitor SKF96365 inhibited the effects 5-HT and DOI on PASMC proliferation and G2M percentage increase, and decreased expression of TRPC1, TRPC6 and calcineurin A/NFATc3 induced by 5-HT and DOI. SKF96365 inhibited binding of NFATc3 and DNA promoted by 5-HT and DOI. Therefore, 5-HT may affect the TRPC channel to promote proliferation of PASMC; upregulate expression of TRPC1, TRPC6, and calcineurin A/NFATc3; and therefore promote NFATc3 nuclear translocation. There may be crosstalk between 5-HT and TRPC, which may contribute to the pathogeneis of pulmonary arterial hypertension and this may be a novel therapeutic target for treating pulmonary arterial hypertension.

Topotecan prevents hypoxia-induced pulmonary arterial hypertension and inhibits hypoxia-inducible factor-1α and TRPC channels.

This study aimed to investigate the effects of topotecan (TPT) on the hypoxia-induced pulmonary arterial hypertension (PAH) in a rat model, and to explore the underlying mechanism. The experiments were carried out in vitro using rat PASMCs and in vivo using a rat model of hypoxia-induced PAH. TPT significantly suppressed the hypoxia-induced upregulation of HIF-1α and TRPC1/4/6 expression both in pulmonary arterial smooth muscle cells (PASMCs) from normal rats and in pulmonary arteries from PAH model rats. Furthermore, TPT effectively inhibited intracellular Ca2+ concentration ([Ca2+]i) change (Ca2+ influx) in PASMCs from both normal rats and PAH model rats. Importantly, TPT treatment significantly inhibited the hypoxia-induced proliferation, migration and a contractile-to-synthetic phenotypic switching of normal rat PASMCs in vitro, where the effect was abrogated by overexpression of TRPC1/4/6. Furthermore, TPT administration potently attenuated the hypoxia-induced PAH-associated pulmonary arteriolar remodeling in PAH model rats, as evidenced by amelioration of elevated hemodynamic parameters, and enhanced right ventricle hypertrophy and wall thickening. TPT ameliorates the hypoxia-induced pulmonary vascular remodeling in PAH, and the mechanism is associated with TPT-mediated inhibition of hypoxia-induced upregulation of HIF-1α and TRPC1/4/6 expression, Ca2+ influx, and PASMCs proliferation.

Sulfur dioxide attenuates hypoxia-induced pulmonary arteriolar remodeling via Dkk1/Wnt signaling pathway

ObjectiveThis study investigated the impact of SO2 on rats with hypoxic pulmonary vascular structural remodeling and its possible mechanisms. Materials and methodsPulmonary vascular morphological change was examined by HE staining. RNA-based high-throughput sequencing (RNA-seq) was performed to detect differential expression of mRNAs in Normal and Hypoxia–induced Pulmonary hypertension (HPH) rats. The Real-time quantitative RT-PCR (q RT-PCR) was used for validation of wnt7b, sfrp2, cacna1f, DKK1, CaSR and vimentin mRNA expression levels. Protein levels of CaSR, Vimentin, Caspase3, E-cadherin and P-Akt1/2/3 were detected by Western blot and immunohistochemistry. ResultsThis study showed that SO2 significantly attenuated the interstitial thickening and prominent media hypertrophy of pulmonary arteries. SO2 downregulated p-Akt1/2/3 protein level and upregulated E-cadherin protein level in lung tissues, which inhibited the proliferation and epithelial-to-mesenchymal transition (EMT) in HPH rats. RNA-seq and PCR validation results showed that levels of Wnt7b, Sfrp2 and Cacna1f mRNAs decreased and Dkk1 mRNA level increased obviously in HPH rats. Moreover, SO2 attenuated the mRNA and protein level of CaSR, which was activated in HPH rats and resulted in the proliferation of PASMCs. Besides, the mRNA and protein expression of vimentin in PASMCs significantly reduced after SO2 treatment. ConclusionTogether, these findings indicate that SO2 could attenuate hypoxia-induced pulmonary arteriolar remodeling and may suppress the proliferation and migration of PASMCs at least in part through the Dkk1/Wnt signaling pathway.

NOX4 expression and distal arteriolar remodeling correlate with pulmonary hypertension in COPD

BackgroundPulmonary hypertension (PH) in chronic obstructive pulmonary disease (COPD) is suggested as the consequence of emphysematous destruction of vascular bed and hypoxia of pulmonary microenvironment, mechanisms underpinning its pathogenesis however remain elusive. The dysregulated expression of nicotinamide adenine dinucleotide phosphate (NADPH)-oxidases and superoxide generation by pulmonary vasculatures have significant implications in the hypoxia-induced PH.MethodsIn this study, the involvement of NADPH oxidase subunit 4 (NOX4) in pulmonary arteriolar remodeling of PH in COPD was investigated by ascertaining the morphological alteration of pulmonary arteries and pulmonary blood flow using cardiac magnetic resonance imaging (cMRI), and the expression and correlation of NOX4 with pulmonary vascular remodeling and pulmonary functions in COPD lungs.ResultsResults demonstrated that an augmented expression of NOX4 was correlated with the increased volume of pulmonary vascular wall in COPD lung. While the volume of distal pulmonary arteries was inversely correlated with pulmonary functions, despite it was positively associated with the main pulmonary artery distensibility, right ventricular myocardial mass end-systolic and right ventricular myocardial mass end-diastolic in COPD. In addition, an increased malondialdehyde and a decreased superoxide dismutase were observed in sera of COPD patients. Mechanistically, the abundance of NOX4 and production of reactive oxygen species (ROS) in pulmonary artery smooth muscle cells could be dynamically induced by transforming growth factor-beta (TGF-β), which in turn led pulmonary arteriolar remodeling in COPD lungs.ConclusionThese results suggest that the NOX4-derived ROS production may play a key role in the development of PH in COPD by promoting distal pulmonary vascular remodeling.

Pulmonary vascular remodeling is prior to the increase in pulmonary hypertension of chronic obstructive pulmonary disease

Objective: To explore the remodeling of pulmonary arterioles in chronic obstructive pulmonary disease (COPD), and its effect on hemorheology of proximal pulmonary arteries, right ventricular structure and function , and the potential mechanisms. Method: A total of 34 patients undergoing surgical treatment for lung tumors admitted to the General Hospital of Ningxia Medical University were included in the study. According to the preoperative lung function, there were 15 patients with COPD complicated with lung tumor (COPD group) and 19 patients with normal pulmonary function with lung tumor (control group). All patients underwent cardiac nuclear magnetic resonance (CMR) before surgery, and the hemorheology of the proximal pulmonary arteries, right ventricular structure and function were obtained by CMR. The normal lung tissues distal to the tumor lesion were taken during the operation, and the morphological changes of the pulmonary arterioles were observed by hematoxylin-eosin staining and Weigert-van Gieson. Immunohistochemistry was used to detect the location and expression of α-smooth muscle actin(SMA) and proliferating cell nuclear antigen(PCNA) in pulmonary arterioles, and the expression of protein and mRNA of α-SMA in lung tissue was detected by Western-blotting and real-time quantitative PCR. Results: The results of CMR showed that mPAP was not statistically different between COPD group and control group (24.0±3.7 vs 22.8±1.6, P>0.05). The main pulmonary artery distensibility (mPAD%), right ventricular myocardial mass end-diastolic (RVMED), right ventricular myocardial mass end-systolic (RVMES), average negative flow(ANF) and regurgitant fraction(RF%) were statistically different between COPD group and control group (P<0.05). The wall thickness (WT), WT% and WA% were significantly higher in COPD group [(37±18) μm, (65±19)% and (55±23)%, respectively] than in control group [(19±3 )μm, (29±5)% and (40±7)%, respectively]. The number of pulmonary arterial smooth muscle cells per unit area and smooth muscle cell proliferation rate were significantly higher in COPD group than in the control group(P<0.01). The expression of α-SMA protein and mRNA in COPD group was higher than that in control group(P<0.05). WA% and WT% were correlated inversely with mPAD%, but positively with RVMES, RVMED and RF%. Conclusions: Pulmonary vascular remodeling and rheological changes, even right heart myocardial structural changes, were observed in COPD patients without pulmonary arterial hypertension. Pulmonary arteriolar remodeling can affect the main pulmonary arterial hemorheology in COPD patients and further affect the myocardial structure of right heart. Pulmonary arterial remodeling may be a new direction for the clinical treatment of COPD.

Cystamine slows but not inverses the progression of monocrotaline-induced pulmonary arterial hypertension in rats.

Tissue transglutaminase (TG2) plays an important role in pulmonary arterial hypertension (PAH). Previous research indicate that TG2 and protein serotonylation catalyzed by TG2 are upregulated in PAH. Serotonin transporter inhibitor fluoxetine ameliorates PAH via inhibition of protein serotonylation. It is still unknown whether PAH is inhibited through direct inhibition of TG2. Therefore, the present study aimed to investigate the effects of TG2 inhibitor cystamine on monocrotaline-induced PAH in rats. Rats were treated with monocrotaline (60 mg·kg-1, i.p.) in combination with or without cystamine (20, 40 mg·kg-1·day-1, p.o.). The results showed that compared with monocrotaline alone, combination of monocrotaline with cystamine (40 mg·kg-1·day-1, p.o.) relieved right ventricle hypertrophy, inhibited pulmonary arteriolar remodeling, and downregulated protein expression of TG2, phosphorylated protein kinase B (Akt), and extracellular regulated protein kinase (ERK) at day 21. However, except for TG2 expression, these changes were not significantly inhibited by cystamine at day 35. In addition, cystamine dose-dependently enhanced the survival rate of rats injected with monocrotaline at day 35. The findings suggest that cystamine slows but not reverses monocrotaline-induced PAH in rats, which was largely associated with the inhibition of TG2 protein expression and Akt and ERK activation.

Exome Sequencing in Children With Pulmonary Arterial Hypertension Demonstrates Differences Compared With Adults

Pulmonary arterial hypertension (PAH) is a rare disease characterized by pulmonary arteriole remodeling, elevated arterial pressure and resistance, and subsequent heart failure. Compared with adult-onset disease, pediatric-onset PAH is more heterogeneous and often associated with worse prognosis. Although BMPR2 mutations underlie ≈70% of adult familial PAH (FPAH) cases, the genetic basis of PAH in children is less understood. We performed genetic analysis of 155 pediatric- and 257 adult-onset PAH patients, including both FPAH and sporadic, idiopathic PAH (IPAH). After screening for 2 common PAH risk genes, mutation-negative FPAH and all IPAH cases were evaluated by exome sequencing. We observed similar frequencies of rare, deleterious BMPR2 mutations in pediatric- and adult-onset patients: ≈55% in FPAH and 10% in IPAH patients in both age groups. However, there was significant enrichment of TBX4 mutations in pediatric- compared with adult-onset patients (IPAH: 10/130 pediatric versus 0/178 adult-onset), and TBX4 carriers had younger mean age-of-onset compared with BMPR2 carriers. Mutations in other known PAH risk genes were infrequent in both age groups. Notably, among pediatric IPAH patients without mutations in known risk genes, exome sequencing revealed a 2-fold enrichment of de novo likely gene-damaging and predicted deleterious missense variants. Mutations in known PAH risk genes accounted for ≈70% to 80% of FPAH in both age groups, 21% of pediatric-onset IPAH, and 11% of adult-onset IPAH. Rare, predicted deleterious variants in TBX4 are enriched in pediatric patients and de novo variants in novel genes may explain ≈19% of pediatric-onset IPAH cases.

Eplerenone attenuates pathological pulmonary vascular rather than right ventricular remodeling in pulmonary arterial hypertension

BackgroundAldosterone is a mineralocorticoid hormone critically involved in arterial blood pressure regulation. Although pharmacological aldosterone antagonism reduces mortality and morbidity among patients with severe left-sided heart failure, the contribution of aldosterone to the pathobiology of pulmonary arterial hypertension (PAH) and right ventricular (RV) heart failure is not fully understood.MethodsThe effects of Eplerenone (0.1% Inspra® mixed in chow) on pulmonary vascular and RV remodeling were evaluated in mice with pulmonary hypertension (PH) caused by Sugen5416 injection with concomitant chronic hypoxia (SuHx) and in a second animal model with established RV dysfunction independent from lung remodeling through surgical pulmonary artery banding.ResultsPreventive Eplerenone administration attenuated the development of PH and pathological remodeling of pulmonary arterioles. Therapeutic aldosterone antagonism – starting when RV dysfunction was established - normalized mineralocorticoid receptor gene expression in the right ventricle without direct effects on either RV structure (Cardiomyocyte hypertrophy, Fibrosis) or function (assessed by non-invasive echocardiography along with intra-cardiac pressure volume measurements), but significantly lowered systemic blood pressure.ConclusionsOur data indicate that aldosterone antagonism with Eplerenone attenuates pulmonary vascular rather than RV remodeling in PAH.

Therapeutic benefits of intravenous cardiosphere-derived cell therapy in rats with pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is a progressive condition characterized by occlusive pulmonary arteriopathy, in which survival remains poor despite pharmacologic advances. The aim of this study was to evaluate the ability of cardiosphere-derived cells (CDCs), cardiac progenitor cells with potent anti-inflammatory and immunomodulatory properties, to attenuate hemodynamic and morphometric remodeling of the right ventricle (RV) and pulmonary arterioles in rats with established monocrotaline (MCT)-induced PAH. Animals were divided into 3 groups: 1) Control (CTL), 2) PAH in which CDCs were centrally infused (CDC) and 3) PAH in which saline was given (Sham). Significant increments in RV systolic pressure (RVSP) and RV hypertrophy were noted in Sham animals compared to CTL. In CDC rats at day 35, RSVP fell (- 38%; p< 0.001) and RV hypertrophy decreased (-26%; p< 0.01). TAPSE and cardiac output were preserved in all 3 groups at day 35. Pulmonary arteriolar wall thickness was greater in Sham rats compared to CTL, and reduced in CDC animals for vessels 20–50 μm (P<0.01; back to CTL levels) and 50–80μm (P<0.01) in diameter. The macrophage population was increased in Sham animals compared to CTL (P< 0.001), but markedly reduced in CDC rats. In conclusion, infusion of CDCs markedly attenuated several key pathophysiologic features of PAH. As adjunctive therapy to PAH-specific agents, CDCs have the potential to impact on the pathobiology of adverse pulmonary arteriolar remodeling, by acting on multiple mechanisms simultaneously.

Statins ameliorate pulmonary hypertension secondary to left ventricular dysfunction through the Rho-kinase pathway and NADPH oxidase.

Pulmonary hypertension (PH) is a devastating disorder, for which no therapy is curative. It has been reported that pulmonary vascular remodeling, associated with increasing mean pulmonary arterial pressure and upregulated expression of endothelial nitric oxide synthase (eNOS), endothelin-1 (ET-1), RhoA/RhoH-kinase results in the development of PH. Oxidative stress and the RhoA/Rho-kinase pathway are also thought to be involved in the pathophysiology of PH. Statins are 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (HMG-CoA reductase inhibitors) with pleiotropic effects and are potential agents for the treatment of PH. In this study, we investigated the beneficial effects of simvastatin on the development of PH secondary to left ventricular dysfunction. A PH secondary to left ventricular dysfunction model was established in 6-week-old aortic-banded rats. The pulmonary expression of Rho kinase, ET-1, eNOS, p-eNOS, nitrite/nitrate (NOx), cGMP, p47Phox , and p67Phox were investigated in the early-treatment group, to which was administered simvastatin (30 mg/kg/day) from days 1 to 42 or the late-treatment group, to which was administered simvastatin (30 mg/kg/day) from days 29 to 42. Simvastatin attenuated the mean pulmonary artery pressure, pulmonary arteriolar remodeling, plasma brain natriuretic peptide, ET-1, reactive oxygen species, and the NADPH oxidase 2 regulatory subunits, p47Phox and p67Phox , and upregulated pulmonary p-eNOS, NOx, and cGMP in both the early- and late-treated groups. Inhibiting HMG-CoA reductase may have therapeutic potential for preventing and attenuating the development of PH in left ventricular dysfunction through the Rho-kinase pathway and NADPH oxidase. A translational study in humans is needed to substantiate these findings. Pediatr Pulmonol. 2017;52:443-457. © 2016 Wiley Periodicals, Inc.

RESVERATROL TREATMENT RESCUES EXAGGERATED RESPONSE TO CHRONIC HYPOXIA IN SIRTUIN-1 MUTANT MICE

Pulmonary Hypertension (PH) is caused by vasoconstriction and remodelling of pulmonary arterioles leading to increased pulmonary vascular resistance, right ventricle hypertrophy and eventually failure. Sirtuin-1 (Sirt1) is an NAD+-dependent deacetylase strongly implicated in maintenance of endothelium homeostasis. Resveratrol is a natural phenol that has been proposed to play a protective role in the vasculature by activation of Sirt1.

Inhibition of heat shock protein 90 improves pulmonary arteriole remodeling in pulmonary arterial hypertension

While the molecular chaperone heat shock protein 90 (HSP90) is involved in a multitude of physiological and pathological processes, its role relating to pulmonary arterial hypertension (PAH) remains unclear. In the present study, we investigated the effect in which HSP90 improves pulmonary arteriole remodeling, and explored the therapeutic utility of targeting HSP90 as therapeutic drug for PAH. By Elisa and immunohistochemistry, HSP90 was found to be increased in both plasma and membrane walls of pulmonary arterioles from PAH patients. Moreover, plasma HSP90 levels positively correlated with mean pulmonary arterial pressure and C-reactive protein. In a monocrotaline-induced rat model of PH, we found that 17-AAG, a HSP90-inhibitor, alleviated the progress of PH, demonstrated by lower pulmonary arterial pressure and absence of right ventricular hypertrophy. Immunohistochemical staining demonstrated that 17-AAG improved pulmonary arteriole remodeling on the basis of reduced wall thickness and wall area. The inflammatory response attributed to PH could be attenuated by 17-AAG through reduction of NF-κB signaling. Moreover, 17-AAG was found to suppress PDGF-stimulated proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) through induction of cell cycle arrest in the G1 phase. In conclusion, HSP90 inhibitor 17-AAG could improve pulmonary arteriole remodeling via inhibiting the excessive proliferation of PASMCs, and inhibition of HSP90 may represent a therapeutic avenue for the treatment of PAH.

Baicalin Attenuates Hypoxia-Induced Pulmonary Arterial Hypertension to Improve Hypoxic Cor Pulmonale by Reducing the Activity of the p38 MAPK Signaling Pathway and MMP-9.

Baicalin has a protective effect on hypoxia-induced pulmonary hypertension in rats, but the mechanism of this effect remains unclear. Thus, investigating the potential mechanism of this effect was the aim of the present study. Model rats that display hypoxic pulmonary hypertension and cor pulmonale under control conditions were successfully generated. We measured a series of indicators to observe the levels of pulmonary arterial hypertension, pulmonary arteriole remodeling, and right ventricular remodeling. We assessed the activation of p38 mitogen-activated protein kinase (MAPK) in the pulmonary arteriole walls and pulmonary tissue homogenates using immunohistochemistry and western blot analyses, respectively. The matrix metalloproteinase- (MMP-) 9 protein and mRNA levels in the pulmonary arteriole walls were measured using immunohistochemistry and in situ hybridization. Our results demonstrated that baicalin not only reduced p38 MAPK activation in both the pulmonary arteriole walls and tissue homogenates but also downregulated the protein and mRNA expression levels of MMP-9 in the pulmonary arteriole walls. This downregulation was accompanied by the attenuation of pulmonary hypertension, arteriole remodeling, and right ventricular remodeling. These results suggest that baicalin may attenuate pulmonary hypertension and cor pulmonale, which are induced by chronic hypoxia, by downregulating the p38 MAPK/MMP-9 pathway.