Progression Of Vascular Remodeling Research Articles

Exosomes enriched by miR-429-3p derived from ITGB1 modified Telocytes alleviates hypoxia-induced pulmonary arterial hypertension through regulating Rac1 expression

BackgroundRecent studies have emphasized the critical role of Telocytes (TCs)-derived exosomes in organ tissue injury and repair. Our previous research showed a significant increase in ITGB1 within TCs. Pulmonary Arterial Hypertension (PAH) is marked by a loss of microvessel regeneration and progressive vascular remodeling. This study aims to investigate whether exosomes derived from ITGB1-modified TCs (ITGB1-Exo) could mitigate PAH.MethodsWe analyzed differentially expressed microRNAs (DEmiRs) in TCs using Affymetrix Genechip miRNA 4.0 arrays. Exosomes isolated from TC culture supernatants were verified through transmission electron microscopy and Nanoparticle Tracking Analysis. The impact of miR-429-3p-enriched exosomes (Exo-ITGB1) on hypoxia-induced pulmonary arterial smooth muscle cells (PASMCs) was evaluated using CCK-8, transwell assay, and inflammatory factor analysis. A four-week hypoxia-induced mouse model of PAH was constructed, and H&E staining, along with Immunofluorescence staining, were employed to assess PAH progression.ResultsForty-five miRNAs exhibited significant differential expression in TCs following ITGB1 knockdown. Mus-miR-429-3p, significantly upregulated in ITGB1-overexpressing TCs and in ITGB1-modified TC-derived exosomes, was selected for further investigation. Exo-ITGB1 notably inhibited the migration, proliferation, and inflammation of PASMCs by targeting Rac1. Overexpressing Rac1 partly counteracted Exo-ITGB1’s effects. In vivo administration of Exo-ITGB1 effectively reduced pulmonary vascular remodeling and inflammation.ConclusionsOur findings reveal that ITGB1-modified TC-derived exosomes exert anti-inflammatory effects and reverse vascular remodeling through the miR-429-3p/Rac1 axis. This provides potential therapeutic strategies for PAH treatment.Graphical 1. Identification of Differentially Expressed microRNAs (DEmiRs) in ITGB1 overexpressed TCs.2. Effects of Exo-ITGB1 or miR-429-3p on Hypoxia-Induced PASMCs in vitro.3. Exo-ITGB1 inhibits the hyper-proliferation and migration of PASMCs through regulating miR-429-3p/Rac1 axis in vitro.4. The therapeutic potential of Exo-ITGB1 in hypoxia-induced PAH model in vivo.

Inhibition of DYRK1A attenuates vascular remodeling in pulmonary arterial hypertension via suppressing STAT3/Pim-1/NFAT pathway

ABSTRACT Pulmonary arterial hypertension (PAH) is characterized by progressive vascular remodeling caused by the excessive proliferation and survival of pulmonary artery smooth muscle cells (PASMCs). Dual-specificity tyrosine regulated kinase 1A (DYRK1A) is a pleiotropic kinase involved in the regulation of multiple biological functions, including cell proliferation and survival. However, the role and underlying mechanisms of DYRK1A in PAH pathogenesis remain unclear. We found that DYRK1A was upregulated in PASMCs in response to hypoxia, both in vivo and in vitro. Inhibition of DYRK1A by harmine significantly attenuated hypoxia-induced pulmonary hypertension and pulmonary artery remodeling. Mechanistically, we found that DYRK1A promoted pulmonary arterial remodeling by enhancing the proliferation and survival of PASMCs through activating the STAT3/Pim-1/NFAT pathway, because STAT3 gain-of-function via adeno-associated virus serotype 2 (AAV2) carrying the constitutively active form of STAT3 (STAT3C) nearly abolished the protective effect of harmine on PAH. Collectively, our results reveal a significant role for DYRK1A in pulmonary arterial remodeling and suggest it as a drug target with translational potential for the treatment of PAH.

Abstract 12249: Activation of Prostaglandin E Receptor 4 Ameliorates Perivascular Inflammation and Pulmonary Hypertension in Rats

Introduction: Perivascular inflammation is involved in the progression of vascular remodeling and pulmonary arterial hypertension (PAH). Activation of prostaglandin E receptor 4 (EP 4 ) has recently been reported to reduce inflammation in ulcerative colitis and osteoarthritis, but there are no reports on perivascular inflammation in PAH. Hypothesis: EP 4 agonist ameliorate perivascular inflammation, vascular remodeling and pulmonary hypertension (PH). Methods and Results: We investigated the effects of EP 4 agonist (KAG-308) on hemodynamics and pulmonary artery remodeling in a monocrotaline (MCT)-exposed rat model of PH. Immunohistochemistry detected predominant expression of EP4 proteins in the macrophages and endothelial layer of pulmonary arteries in the lungs of normal and MCT-exposed rats. Compared to normal rats, MCT-exposed rats had increased nuclear factor kappa B (NFκB) activation and significantly higher interleukin 6 ( IL -6) mRNA levels (1.0±0.4 vs 62.3±39.7, p < 0.05) in the lungs, and showed elevated right ventricular systolic pressure (RVSP; 29.7±1.8 vs 81.0±18.5 mmHg, p < 0.0001), total pulmonary vascular resistance index (TPRI; 91.0±12.1 vs 161.4 ± 37.0 mmHg/mL/min/g, p < 0.001) and RV hypertrophy (0.32±0.02 vs 0.57±0.10, p < 0.0001), together with medial wall thickening and perivascular macrophage accumulation on day 21 after MCT injection. Oral administration of EP 4 agonist KAG-308 (1 mg/kg, twice daily, by gavage, day 0 to 21) significantly reduced NFκB activation and interleukin-6 mRNA levels (6.8 ± 2.5, p < 0.05) in the lungs. Furthermore, KAG-308 prevented the elevated RVSP (53.1 ± 9.3 mmHg, p < 0.01), TPRI (112.0 ± 16.6 mmHg/mL/min/g, p < 0.05) and RV hypertrophy (0.47 ± 0.04, p < 0.05) by inhibiting medical wall thickening and macrophage accumulation. Conclusion: EP 4 agonist ameliorated inflammation, vascular remodeling and PH in MCT-exposed rat. The EP 4 agonist KAG-308 is a potential therapeutic agent for the treatment of PAH.

Abstract 19002: Impact of Pulmonary Hypertension on Covid-19 Pneumonia Hospitalizations: Analysis of The National Inpatient Sample 2020

Background: SARS-CoV-2 swept across the globe, overwhelming healthcare systems across the world regardless of borders and socioeconomic factors. COVID pneumonia (CP) can result in ARDS and increased pulmonary artery pressures. Pulmonary hypertension (PHT) is generally a chronic cardiopulmonary disease that is associated with progressive vascular remodeling. We aimed to assess the impact of underlying PHT on CP patients with a large sample size. Methods: We utilized the National Inpatient Sample from 2020 to identify 1,058,815 hospitalized adults with CP. These hospitalizations were further stratified based on the presence of PHT. A multivariate regression model was used to adjust for confounders and analyze the variables. Results: Of those who were admitted for CP, 24,284 (2.3%) had PHT. In-hospital mortality was higher in those with PHT (19.6% vs 10.9%; p<0.001). Figure 1 shows the Forrest plot for multivariate analysis of in-hospital outcomes when adjusted for patient demographics, comorbidities, and hospital characteristics. When adjusted similarly, CP patients with PHT had longer length of stay (LOS) by 1.3 days (p<0.001) and had additional hospital costs (HC) of $23,232 (p<0.001). Conclusions: CP patients who had PHT had significantly worse outcomes in terms of in-hospital mortality, LOS, HC, cardiac arrest, arrhythmias, sepsis, cardiogenic shock, and being intubated. These patients are unable to tolerate the ventilation-perfusion mismatch and the rise in pulmonary arterial pressures seen in ARDS.

Endothelial RIPK1 protects artery bypass graft against arteriosclerosis by regulating SMC growth.

RIPK1 is crucial in the inflammatory response. The process of vascular graft remodeling is also involved in endothelial inflammation, which can influence the behavior of smooth muscle cells. However, the role of endothelial RIPK1 in arterial bypass grafts remains unknown. Here, we established an arterial isograft mouse model in wild-type and endothelial RIPK1 conditional knockout mice. Progressive vascular remodeling and neointima formation occurred in the graft artery, showing SMC accumulation together with endothelial inflammatory adhesion molecule and cytokine expression. Endothelial RIPK1 knockout exacerbated graft stenosis by increasing secretion of N-Shh. Mechanistically, RIPK1 directly phosphorylated EEF1AKMT3 at Ser26, inhibiting its methyltransferase activity and global protein synthesis, which further attenuated N-Shh translation and secretion. Consistently, treatment with the Hedgehog pathway inhibitor GDC0449 markedly alleviated RIPK1 knockout-induced graft stenosis. Our results demonstrated that endothelial RIPK1 played a protective role in arterial bypass graft vascular remodeling, highlighting that targeting Hedgehog pathway may be an attractive strategy for graft failure in the future.

Single-cell RNA landscape of cell heterogeneity and immune microenvironment in ligation-induced vascular remodeling in rat

Background and aimsVascular remodeling is a common pathological basis for cardiovascular diseases. Although both immune and non-immune cells have been suggested to contribute to this process, the complex cellular heterogeneity and intercellular interactions remain largely uncharacterized. Methods and ResultsIn this study, we simulated early and late vascular remodeling by ligating the rat carotid artery for 1 week and 4 weeks, respectively. Using single-cell RNA-sequencing, we characterized gene expression signatures and driver signals of major cell types involved in vascular remodeling. Focused analysis revealed a novel sub-population of Selenbp1hi smooth muscle cells (SMCs) associated with vascular remodeling. Results of intercellular communication analyses predicted several ligand-receptor pairs between immune cells with SMCs and endothelial cells (ECs), implicating SMCs apoptosis and repair, ECs aging and inflammatory responses. ConclusionsWe present a comprehensive single-cell atlas of vascular cells in early and late stages of ligated rat carotid artery, providing valuable insights into the understanding of the initiation and progression of vascular remodeling.

G9a/GLP Targeting Ameliorates Pulmonary Vascular Remodeling in Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is characterized by progressive vascular remodeling of small pulmonary arteries (PAs) causing sustained elevation of PA pressure, right ventricular failure, and death. Similar to cancer cells, PA smooth muscle cells (PASMCs), which play a key role in pulmonary vascular remodeling, have adopted multiple mechanisms to sustain their survival and proliferation in the presence of stress. The histone methyltransferase G9a and its partner protein GLP (G9a-like protein) have been shown to exert oncogenic effects and to serve as a buffer against an exaggerated transcriptional response. Therefore, we hypothesized that upregulation of G9a and GLP in PAH plays a pivotal role in pulmonary vascular remodeling by maintaining the abnormal phenotype of PAH-PASMCs. We found that G9a is increased in PASMCs from patients with PAH as well as in remodeled PAs from animal models. Pharmacological inhibition of G9a/GLP activity using BIX01294 and UNC0642 significantly reduced the prosurvival and proproliferative potentials of cultured PAH-PASMCs. Using RNA sequencing, further exploration revealed that G9a/GLP promotes extracellular matrix production and affords protection against the negative effects of an overactive stress response. Finally, we found that therapeutic treatment with BIX01294 reduced pulmonary vascular remodeling and lowered mean PA pressure in fawn-hooded rats. Treatment of Sugen/hypoxia-challenged mice with BIX01294 also improved pulmonary hemodynamics and right ventricular function. In conclusion, these findings indicate that G9a/GLP inhibition may represent a new therapeutic approach in PAH.

Effects of atorvastatin in suppressing pulmonary vascular remodeling in rats with chronic obstructive pulmonary disease

ObjectiveTo investigate the effects of atorvastatin calcium on pulmonary vascular remodeling, the authors explored the regulatory mechanism of Histone Deacetylation Enzyme-2 (HDAC2) in rats with Chronic Obstructive Pulmonary Disease (COPD), and provided a new direction for drug treatment in the progression of vascular remodeling. MethodsEighteen female SD rats were randomly divided into control (Group S1), COPD (Group S2), and atorvastatin calcium + COPD (Group S3) groups. A COPD rat model was established by passive smoking and intratracheal injection of Lipopolysaccharide (LPS). Haematoxylin and eosin staining and Victoria Blue + Van Gibson staining were used to observe pathological changes in the lung tissue. The pulmonary vascular inflammation score was calculated, and the degree of pulmonary vascular remodeling was evaluated. The ratio of Muscular Arteries in lung tissue (MA%), the ratio of the vessel Wall Area to the vessel total area (WA%), and the ratio of the vessel Wall Thickness to the vascular outer diameter (WT%) were measured using imaging software. The expression of HDAC2 was measured using western blotting, ELISA (Enzyme-Linked Immunosorbent Assay), and qPCR (Real-time PCR). ResultsCompared with the control group, the degree of pulmonary vascular inflammation and pulmonary vascular remodeling increased in rats with COPD. The WT%, WA%, and lung inflammation scores increased significantly; the expression of HDAC2 and HDAC2mRNA in the serum and lung tissue decreased, and the level of Vascular Endothelial Growth Factor (VEGF) in the lung tissues increased (p < 0.05). Compared with the COPD group, the lung tissues from rats in the atorvastatin group had fewer inflammatory cells, and the vascular pathological changes were significantly relieved. The WT%, WA%, and lung inflammation scores decreased significantly; the expression of HDAC2 and HDAC2mRNA in the serum and lung tissues increased, and the level of VEGF in the lung tissues decreased (p < 0.05). ConclusionThe present study revealed that atorvastatin calcium could regulate the contents and expression of HDAC2 in serum and lung tissues and inhibit the production of VEGF, thereby regulating pulmonary vascular remodeling in a rat model with COPD.

Hydroxysafflower Yellow A Inhibits Vascular Adventitial Fibroblast Migration via NLRP3 Inflammasome Inhibition through Autophagy Activation

Inflammation is closely associated with progression of vascular remodeling. The NLRP3 inflammasome is the key molecule that promotes vascular remodeling via activation of vascular adventitia fibroblast (VAF) proliferation and differentiation. VAFs have a vital effect on vascular remodeling that could be improved using hydroxysafflower yellow A (HSYA). However, whether HSYA ameliorates vascular remodeling through inhibition of NLRP3 inflammasome activation has not been explored in detail. Here, we cultured primary VAFs and analyzed the migration of VAFs induced by angiotensin II (ANG II) to determine the potential effects and mechanism of HSYA on VAF migration. The results thereof showed that HSYA remarkably inhibited ANG II-induced VAF migration, NLRP3 inflammasome activation, and the TLR4/NF-κB signaling pathway in a dose-dependent manner. In addition, it is worth noting that LPS promoted ANG II-induced VAF migration and NLRP3 inflammasome assembly, which could be significantly reversed using HSYA. Moreover, HSYA could be used to inhibit NLRP3 inflammasome activation by promoting autophagy. In conclusion, HSYA could inhibit ANG II-induced VAF migration through autophagy activation and inhibition of NLRP3 inflammasome activation through the TLR4/NF-κB signaling pathway.

Single-cell transcriptomics reveals skewed cellular communication and phenotypic shift in pulmonary artery remodeling.

A central feature of progressive vascular remodeling is altered smooth muscle cell (SMC) homeostasis; however, the understanding of how different cell populations contribute to this process is limited. Here, we utilized single-cell RNA sequencing to provide insight into cellular composition changes within isolated pulmonary arteries (PAs) from pulmonary arterial hypertension and donor lungs. Our results revealed that remodeling skewed the balanced communication network between immune and structural cells, in particular SMCs. Comparative analysis with murine PAs showed that human PAs harbored heterogeneous SMC populations with an abundant intermediary cluster displaying a gradient transition between SMCs and adventitial fibroblasts. Transcriptionally distinct SMC populations were enriched in specific biological processes and could be differentiated into 4 major clusters: oxygen sensing (enriched in pericytes), contractile, synthetic, and fibroblast-like. End-stage remodeling was associated with phenotypic shift of preexisting SMC populations and accumulation of synthetic SMCs in neointima. Distinctly regulated genes in clusters built nonredundant regulatory hubs encompassing stress response and differentiation regulators. The current study provides a blueprint of cellular and molecular changes on a single-cell level that are defining the pathological vascular remodeling process.

HMGB1 increases RAGE expression in vascular smooth muscle cells via ERK and p-38 MAPK-dependent pathways.

The increased expression of receptors for advanced glycation end-product (RAGE) is known as a key player in the progression of vascular remodeling. However, the precise signal pathways regulating RAGE expression in vascular smooth muscle cells (VSMCs) in the injured vasculatures are unclear. Given the importance of mitogen-activated protein kinase (MAPK) signaling in cell proliferation, we investigated the importance of MAPK signaling in high-mobility group box 1 (HMGB1)-induced RAGE expression in VSMCs. In HMGB1 (100 ng/ml)-stimulated human VSMCs, the expression of RAGE mRNA and protein was increased in association with an increase in AGE-induced VSMC proliferation. The HMGB1-induced RAGE expression was attenuated in cells pretreated with inhibitors for ERK (PD98059, 10 μM) and p38 MAPK (SB203580, 10 μM) as well as in cells deficient in ERK and p38 MAPK using siRNAs, but not in cells deficient of JNK signaling. In cells stimulated with HMGB1, the phosphorylation of ERK, JNK, and p38 MAPK was increased. This increase in ERK and p38 MAPK phosphorylation was inhibited by p38 MAPK and ERK inhibitors, respectively, but not by JNK inhibitor. Moreover, AGE-induced VSMC proliferation in HMGB1-stimulated cells was attenuated in cells treated with ERK and p38 MAPK inhibitors. Taken together, our results indicate that ERK and p38 MAPK signaling are involved in RAGE expression in HMGB1-stimulated VSMCs. Thus, the ERK/p38 MAPK-RAGE signaling axis in VSMCs was suggested as a potential therapeutic target for vascular remodeling in the injured vasculatures.

A Novel Protective Role for Matrix Metalloproteinase-8 in the Pulmonary Vasculature.

Rationale: Mechanical signaling through cell-matrix interactions plays a major role in progressive vascular remodeling in pulmonary arterial hypertension (PAH). MMP-8 (matrix metalloproteinase-8) is an interstitial collagenase involved in regulating inflammation and fibrosis of the lung and systemic vasculature, but its role in PAH pathogenesis remains unexplored. Objectives: To evaluate MMP-8 as a modulator of pathogenic mechanical signaling in PAH. Methods: MMP-8 levels were measured in plasma from patients with pulmonary hypertension (PH) and controls by ELISA. MMP-8 vascular expression was examined in lung tissue from patients with PAH and rodent models of PH. MMP-8-/- and MMP-8+/+ mice were exposed to normobaric hypoxia or normoxia for 4-8 weeks. PH severity was evaluated by right ventricular systolic pressure, echocardiography, pulmonary artery morphometry, and immunostaining. Proliferation, migration, matrix component expression, and mechanical signaling were assessed in MMP-8-/- and MMP-8+/+ pulmonary artery smooth muscle cells (PASMCs). Measurements and Main Results: MMP-8 expression was significantly increased in plasma and pulmonary arteries of patients with PH compared with controls and induced in the pulmonary vasculature in rodent PH models. Hypoxia-exposed MMP-8-/- mice had significant mortality, increased right ventricular systolic pressure, severe right ventricular dysfunction, and exaggerated vascular remodeling compared with MMP-8+/+ mice. MMP-8-/- PASMCs demonstrated exaggerated proliferation and migration mediated by altered matrix protein expression, elevated integrin-β3 levels, and induction of FAK (focal adhesion kinase) and downstream YAP (Yes-associated protein)/TAZ (transcriptional coactivator with PDZ-binding motif) activity. Conclusions: MMP-8 is a novel protective factor upregulated in the pulmonary vasculature during PAH pathogenesis. MMP-8 opposes pathologic mechanobiological feedback by altering matrix composition and disrupting integrin-β3/FAK and YAP/TAZ-dependent mechanical signaling in PASMCs.

The Mechanobiology of Vascular Remodeling in the Aging Lung.

Aging is accompanied by declining lung function and increasing susceptibility to lung diseases. The role of endothelial dysfunction and vascular remodeling in these changes is supported by growing evidence, but underlying mechanisms remain elusive. In this review we summarize functional, structural, and molecular changes in the aging pulmonary vasculature and explore how interacting aging and mechanobiological cues may drive progressive vascular remodeling in the lungs.

Apelin receptor upregulation in spontaneously hypertensive rat contributes to the enhanced vascular smooth muscle cell proliferation by activating autophagy.

BackgroundProliferation of vascular smooth muscle cells (VSMCs) plays a vital role in the progression of vascular remodeling and hypertension. Apelin-13 promotes VSMC proliferation of normal rats. This study was designed to investigate the roles of apelin receptor (APJ) and apelin-13 in VSMC proliferation of hypertension rats and underlying mechanisms.MethodsPrimary VSMCs were obtained from aorta of Wistar-Kyoto rat (WKY) and spontaneously hypertensive rat (SHR). The expressions of apelin and APJ were detected by Western bolt and PCR, as well as immunohistochemistry. VSMC proliferation was evaluated with CCK-8 kit, PCNA protein expression and percentage of EdU-positive cells. Autophagy was determined by the ratio of LC3BII to LC3BI, ATG5 and p62 protein expressions, as well as LC3B immunofluorescence.ResultsAPJ expression was increased while apelin expression was reduced in aorta and VSMCs of SHR compared with those of WKY. Exogenous apelin-13 promoted VSMC proliferation and autophagy of both WKY and SHR, which were prevented by APJ antagonist F13A. Blockade of APJ had no significant effects on VSMC proliferation and autophagy of WKY, but attenuated VSMC proliferation and autophagy of SHR. Administration of autophagy inhibitor 3-methyladenine (3-MA) not only attenuated VSMC proliferation of SHR, but prevented apelin-13-induced VSMC proliferation of both WKY and SHR.ConclusionsApelin-13 stimulates VSMC proliferation via APJ-mediated enhancement in autophagy. APJ upregulation in SHR contributes to the enhanced VSMC proliferation.

Novel Advances in Modifying BMPR2 Signaling in PAH.

Pulmonary Arterial Hypertension (PAH) is a disease of the pulmonary arteries, that is characterized by progressive narrowing of the pulmonary arterial lumen and increased pulmonary vascular resistance, ultimately leading to right ventricular dysfunction, heart failure and premature death. Current treatments mainly target pulmonary vasodilation and leave the progressive vascular remodeling unchecked resulting in persistent high morbidity and mortality in PAH even with treatment. Therefore, novel therapeutic strategies are urgently needed. Loss of function mutations of the Bone Morphogenetic Protein Receptor 2 (BMPR2) are the most common genetic factor in hereditary forms of PAH, suggesting that the BMPR2 pathway is fundamentally important in the pathogenesis. Dysfunctional BMPR2 signaling recapitulates the cellular abnormalities in PAH as well as the pathobiology in experimental pulmonary hypertension (PH). Approaches to restore BMPR2 signaling by increasing the expression of BMPR2 or its downstream signaling targets are currently actively explored as novel ways to prevent and improve experimental PH as well as PAH in patients. Here, we summarize existing as well as novel potential treatment strategies for PAH that activate the BMPR2 receptor pharmaceutically or genetically, increase the receptor availability at the cell surface, or reconstitute downstream BMPR2 signaling.

Abstract 15227: Egln1 Deficiency Induce Alveolar Macrophages Accumulation and Polarize Lung Interstitial Macrophages to a Pro-pah State Mediating Obliterative Pulmonary Vascular Remodeling and Severe PAH

Introduction: Previously we identified a mouse model (Tie2Cre-mediated disruption of Egln1 ) of Pulmonary arterial hypertension (PAH) with progressive obliterative vascular remodeling including vascular occlusion and plexiform-like lesions and right heart failure. Tie2Cre-meidated disruption of Egln1 in bone marrow contributes to the severity of PAH indicating the importance of the immune cells in the pathogenesis of PH. Hypothesis: Macrophage accumulation and polarization due to Egln1 deficiency contributes to obliterative pulmonary vascular remodeling and severe PAH in Egln1 Tie2Cre mice. Methods: Egln1 Tie2Cre mice with macrophage Fas-Induced apoptosis (MaFIA) transgene were generated (Egln1 Tie2Cre /MaFIA) and received AP20187 treatment to deplete the macrophages during the development of PAH afterwards the RVSP and RV/(LV+S) ratio were measured as the indicator of diseases severity. Flowcytometry and immunostaining were used to quantify different types of macrophages. Bulk RNA-seq and single cell RNA-seq were used to identify PAH-related pathway changes and population changes of lung macrophages in Egln1 Tie2Cre mice. BrdU staining was used to measure the smooth muscle cell (SMC) proliferation co-culturing with macrophages isolated from Egln1 Tie2Cre mice. Results: We observed that CD206+ Alternative Activated Macrophages (AAMs) are accumulated in the pulmonary vessel adventitia of IPAH patients as well as Egln1 Tie2Cre mice. These macrophages are Egln1 deficient and express elevated level of pro-PAH factors and thus promote SMC proliferation in vitro . Moreover, genetic depletion of total macrophages using the Egln1 Tie2Cre /MaFIA mouse model markedly inhibited obliterative pulmonary vascular remodeling and PAH. Single cell RNA-seq revealed that lung resident alveolar macrophages (Siglec-F+/Cd11c+) accumulated due to hyper-proliferation while recruited lung interstitial (Cx3cr1+/Aif1+) macrophages polarize to a pro-PAH state in Egln1 Tie2Cre mice. Conclusions: Egln1 deficiency in the HCs induced proliferation/accumulation of alveolar macrophages and polarized the recruited interstitial macrophages to AAM state which contributes to the vascular remodeling by secreting pro-PAH factors.

Endothelial Basement Membrane Components and Their Products, Matrikines: Active Drivers of Pulmonary Hypertension?

Pulmonary arterial hypertension (PAH) is a vascular disease that is characterized by elevated pulmonary arterial pressure (PAP) due to progressive vascular remodeling. Extracellular matrix (ECM) deposition in pulmonary arteries (PA) is one of the key features of vascular remodeling. Emerging evidence indicates that the basement membrane (BM), a specialized cluster of ECM proteins underlying the endothelium, may be actively involved in the progression of vascular remodeling. The BM and its steady turnover are pivotal for maintaining appropriate vascular functions. However, the pathologically elevated turnover of BM components leads to an increased release of biologically active short fragments, which are called matrikines. Both BM components and their matrikines can interfere with pivotal biological processes, such as survival, proliferation, adhesion, and migration and thus may actively contribute to endothelial dysfunction. Therefore, in this review, we summarize the emerging role of the BM and its matrikines on the vascular endothelium and further discuss its implications on lung vascular remodeling in pulmonary hypertension.

Progression of vascular remodeling in pulmonary vein obstruction

ObjectivesPulmonary vein obstruction (PVO) frequently occurs after repair of total anomalous pulmonary vein connection with progression of intimal hyperplasia from the anastomotic site toward upstream pulmonary veins (PVs). However, the understanding of mechanism in PVO progression is constrained by lack of data derived from a physiological model of the disease, and no prophylaxis has been established. We developed a new PVO animal model, investigated the mechanisms of PVO progression, and examined a new prophylactic strategy. MethodsWe developed a chronic PVO model using infant domestic pigs by cutting and resuturing the left lower PV followed by weekly hemodynamic parameter measurement and angiographic assessment of the anastomosed PV. Subsequently, we tested a novel therapeutic strategy with external application of rapamycin-eluting film to the anastomotic site. ResultsWe found the pig PVO model mimicked human PVO hemodynamically and histopathologically. This model exhibited increased expression levels of Ki-67 and phospho-mammalian target of rapamycin in smooth muscle-like cells at the anastomotic neointima. In addition, contractile to synthetic phenotypic transition; that is, dedifferentiation of smooth muscle cells and mammalian target of rapamycin pathway activation in the neointima of upstream PVs were observed. Rapamycin-eluting films externally applied around the anastomotic site inhibited the activation of mammalian target of rapamycin in the smooth muscle-like cells of neointima, and delayed PV anastomotic stenosis. ConclusionsWe demonstrate the evidence on dedifferentiation of smooth muscle-like cells and mammalian target of rapamycin pathway activation in the pathogenesis of PVO progression. Delivery of rapamycin to the anastomotic site from the external side delayed PV anastomotic stenosis, implicating a new therapeutic strategy to prevent PVO progression.

Combination therapy improves vascular volume in female rats with pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is a female predominant disease in which progressive vascular remodeling and vasoconstriction result in right ventricular (RV) failure and death. Most PAH patients utilize multiple therapies. In contrast, the majority of preclinical therapeutic studies are performed in male rats with a single novel drug often markedly reversing disease in the model. We sought to differentiate single drug therapy from combination therapy in female rats with severe disease. One week after left pneumonectomy, we induced PH in young female Sprague-Dawley rats with an injection of monocrotaline (45 mg/kg). Female rats were then randomized to receive combination therapy (ambrisentan plus tadalafil), ambrisentan monotherapy, tadalafil monotherapy, or vehicle. We measured RV size and function on two serial echocardiograms during the development of disease. We measured RV systolic pressure (RVSP) invasively at day 28 after monocrotaline before analyzing the vascular volume with microcomputed tomography (microCT) of the right middle lobe. RVSP was significantly lower in female rats treated with combination therapy, and combination therapy resulted in increased small vessel volume density measured by microCT compared with untreated rats. Combination-treated rats had the smallest RV end-diastolic diameter on echocardiogram as compared with the other groups. In summary, we report a female model of pulmonary hypertension that can distinguish between one and two drug therapies; this model may facilitate better preclinical drug testing for novel compounds.

Inhibition of CHK 1 (Checkpoint Kinase 1) Elicits Therapeutic Effects in Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is a debilitating disease associated with progressive vascular remodeling of distal pulmonary arteries leading to elevation of pulmonary artery pressure, right ventricular hypertrophy, and death. Although presenting high levels of DNA damage that normally jeopardize their viability, pulmonary artery smooth muscle cells (PASMCs) from patients with PAH exhibit a cancer-like proproliferative and apoptosis-resistant phenotype accounting for vascular lumen obliteration. In cancer cells, overexpression of the serine/threonine-protein kinase CHK1 (checkpoint kinase 1) is exploited to counteract the excess of DNA damage insults they are exposed to. This study aimed to determine whether PAH-PASMCs have developed an orchestrated response mediated by CHK1 to overcome DNA damage, allowing cell survival and proliferation. Approach and Results: We demonstrated that CHK1 expression is markedly increased in isolated PASMCs and distal PAs from patients with PAH compared with controls, as well as in multiple complementary animal models recapitulating the disease, including monocrotaline rats and the simian immunodeficiency virus-infected macaques. Using a pharmacological and molecular loss of function approach, we showed that CHK1 promotes PAH-PASMCs proliferation and resistance to apoptosis. In addition, we found that inhibition of CHK1 induces downregulation of the DNA repair protein RAD 51 and severe DNA damage. In vivo, we provided evidence that pharmacological inhibition of CHK1 significantly reduces vascular remodeling and improves hemodynamic parameters in 2 experimental rat models of PAH. Our results show that CHK1 exerts a proproliferative function in PAH-PASMCs by mitigating DNA damage and suggest that CHK1 inhibition may, therefore, represent an attractive therapeutic option for patients with PAH.