scholarly journals Aneurysm-type plexiform lesions form in supernumerary arteries in pulmonary arterial hypertension: potential therapeutic implications

2019 ◽  
Vol 317 (6) ◽  
pp. L805-L815 ◽  
Author(s):  
Kaori Oshima ◽  
Edward S. Crockett ◽  
Sachindra R. Joshi ◽  
Jared M. McLendon ◽  
Yuri Matsumoto ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Pulmonary Arterial Hypertension ◽  
Arterial Hypertension ◽  
Late Stage ◽  
Pulmonary Arteries ◽  
Microvascular Endothelial Cells ◽  
Pulmonary Microvascular Endothelial Cells ◽  
Plexiform Lesions ◽  
Pulmonary Arterial ◽  
Anatomical Properties

Histological observations in human pulmonary arterial hypertension (PAH) suggest a link between plexiform lesions and pulmonary supernumerary arteries. Pulmonary microvascular endothelial cells are characterized as hyperproliferative and progenitor-like. This study investigates the hypothesis that aneurysm-type plexiform lesions form in pulmonary supernumerary arteries because of their anatomical properties and endothelial characteristics similar to pulmonary microvascular endothelial cells. To induce PAH, rats were injected with Sugen5416, and exposed to hypoxia (10% O2) for 3 days (early stage) or 3 wk (mid-stage), or 3 wk of hypoxia with an additional 10 wk of normoxia (late-stage PAH). We examined morphology of pulmonary vasculature and vascular remodeling in lung serial sections from PAH and normal rats. Aneurysm-type plexiform lesions formed in small side branches of pulmonary arteries with morphological characteristics similar to supernumerary arteries. Over the course of PAH development, the number of Ki67-positive cells increased in small pulmonary arteries, including supernumerary arteries, whereas the number stayed consistently low in large pulmonary arteries. The increase in Ki67-positive cells was delayed in supernumerary arteries compared with small pulmonary arteries. In late-stage PAH, ~90% of small unconventional side branches that were likely to be supernumerary arteries were nearly closed. These results support our hypothesis that supernumerary arteries are the predominant site for aneurysm-type plexiform lesions in Sugen5416/hypoxia/normoxia-exposed PAH rats partly because of the combination of their unique anatomical properties and the hyperproliferative potential of endothelial cells. We propose that the delayed and extensive occlusive lesion formation in supernumerary arteries could be a preventive therapeutic target in patients with PAH.

scholarly journals Cytoskeletal defects in Bmpr2-associated pulmonary arterial hypertension

2012 ◽  
Vol 302 (5) ◽  
pp. L474-L484 ◽  
Author(s):  
Jennifer A. Johnson ◽  
Anna R. Hemnes ◽  
Daniel S. Perrien ◽  
Manfred Schuster ◽  
Linda J. Robinson ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Pulmonary Arterial Hypertension ◽  
Arterial Hypertension ◽  
Rho Gtpase ◽  
Microvascular Endothelial Cells ◽  
Pulmonary Microvascular Endothelial Cells ◽  
Pulmonary Arterial ◽  
Cytoskeletal Function ◽  
Microvascular Endothelial

The heritable form of pulmonary arterial hypertension (PAH) is typically caused by a mutation in bone morphogenic protein receptor type 2 ( BMPR2), and mice expressing Bmpr2 mutations develop PAH with features similar to human disease. BMPR2 is known to interact with the cytoskeleton, and human array studies in PAH patients confirm alterations in cytoskeletal pathways. The goal of this study was to evaluate cytoskeletal defects in BMPR2-associated PAH. Expression arrays on our Bmpr2 mutant mouse lungs revealed cytoskeletal defects as a prominent molecular consequence of universal expression of a Bmpr2 mutation (Rosa26-Bmpr2R899X). Pulmonary microvascular endothelial cells cultured from these mice have histological and functional cytoskeletal defects. Stable transfection of different BMPR2 mutations into pulmonary microvascular endothelial cells revealed that cytoskeletal defects are common to multiple BMPR2 mutations and are associated with activation of the Rho GTPase, Rac1. Rac1 defects are corrected in cell culture and in vivo through administration of exogenous recombinant human angiotensin-converting enzyme 2 (rhACE2). rhACE2 reverses 77% of gene expression changes in Rosa26-Bmpr2R899X transgenic mice, in particular, correcting defects in cytoskeletal function. Administration of rhACE2 to Rosa26-Bmpr2R899X mice with established PAH normalizes pulmonary pressures. Together, these findings suggest that cytoskeletal function is central to the development of BMPR2-associated PAH and that intervention against cytoskeletal defects may reverse established disease.

scholarly journals Hypoxia-inducible factors in human pulmonary arterial hypertension: a link to the intrinsic myeloid abnormalities

Blood ◽  
2011 ◽  
Vol 117 (13) ◽  
pp. 3485-3493 ◽  
Author(s):  
Samar Farha ◽  
Kewal Asosingh ◽  
Weiling Xu ◽  
Jacqueline Sharp ◽  
Deepa George ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Endothelial Cells ◽  
Pulmonary Arterial Hypertension ◽  
Arterial Hypertension ◽  
Hypoxia Inducible Factor ◽  
Pulmonary Arteries ◽  
Disease Process ◽  
Pulmonary Vasculature ◽  
Normal Numbers ◽  
Pulmonary Arterial

AbstractPulmonary arterial hypertension (PAH) is a proliferative vasculopathy characterized by high circulating CD34+CD133+ proangiogenic progenitors, and endothelial cells that have pathologic expression of hypoxia-inducible factor 1 α (HIF-1α). Here, CD34+CD133+ progenitor cell numbers are shown to be higher in PAH bone marrow, blood, and pulmonary arteries than in healthy controls. The HIF-inducible myeloid-activating factors erythropoietin, stem cell factor (SCF), and hepatocyte growth factor (HGF) are also present at higher than normal levels in PAH blood, and related to disease severity. Primary endothelial cells harvested from human PAH lungs produce greater HGF and progenitor recruitment factor stromal-derived factor 1 α (SDF-1α) than control lung endothelial cells, and thus may contribute to bone marrow activation. Even though PAH patients had normal numbers of circulating blood elements, hematopoietic alterations in myeloid and erythroid lineages and reticulin fibrosis identified a subclinical myeloproliferative process. Unexpectedly, evaluation of bone marrow progenitors and reticulin in nonaffected family members of patients with familial PAH revealed similar myeloid abnormalities. Altogether, the results show that PAH is linked to myeloid abnormalities, some of which may be related to increased production of HIF-inducible factors by diseased pulmonary vasculature, but findings in nonaffected family suggest myeloid abnormalities may be intrinsic to the disease process.

scholarly journals Regulation of mitochondrial fragmentation in microvascular endothelial cells isolated from the SU5416/hypoxia model of pulmonary arterial hypertension

2019 ◽  
Vol 317 (5) ◽  
pp. L639-L652 ◽  
Author(s):  
Karthik Suresh ◽  
Laura Servinsky ◽  
Haiyang Jiang ◽  
Zahna Bigham ◽  
Joel Zaldumbide ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Pulmonary Arterial Hypertension ◽  
Arterial Hypertension ◽  
Microvascular Endothelial Cells ◽  
Pulmonary Vasculature ◽  
Mitochondrial Morphology ◽  
Transient Receptor Potential Vanilloid ◽  
Mitochondrial Fragmentation ◽  
Pulmonary Arterial ◽  
Microvascular Endothelial

Pulmonary arterial hypertension (PAH) is a morbid disease characterized by progressive right ventricle (RV) failure due to elevated pulmonary artery pressures (PAP). In PAH, histologically complex vaso-occlusive lesions in the pulmonary vasculature contribute to elevated PAP. However, the mechanisms underlying dysfunction of the microvascular endothelial cells (MVECs) that comprise a significant portion of these lesions are not well understood. We recently showed that MVECs isolated from the Sugen/hypoxia (SuHx) rat experimental model of PAH (SuHx-MVECs) exhibit increases in migration/proliferation, mitochondrial reactive oxygen species (ROS; mtROS) production, intracellular calcium levels ([Ca2+]i), and mitochondrial fragmentation. Furthermore, quenching mtROS with the targeted antioxidant MitoQ attenuated basal [Ca2+]i, migration and proliferation; however, whether increased mtROS-induced [Ca2+]i entry affected mitochondrial morphology was not clear. In this study, we sought to better understand the relationship between increased ROS, [Ca2+]i, and mitochondrial morphology in SuHx-MVECs. We measured changes in mitochondrial morphology at baseline and following inhibition of mtROS, with the targeted antioxidant MitoQ, or transient receptor potential vanilloid-4 (TRPV4) channels, which we previously showed were responsible for mtROS-induced increases in [Ca2+]i in SuHx-MVECs. Quenching mtROS or inhibiting TRPV4 attenuated fragmentation in SuHx-MVECs. Conversely, inducing mtROS production in MVECs from normoxic rats (N-MVECs) increased fragmentation. Ca2+ entry induced by the TRPV4 agonist GSK1017920A was significantly increased in SuHx-MVECs and was attenuated with MitoQ treatment, indicating that mtROS contributes to increased TRPV4 activity in SuHx-MVECs. Basal and maximal respiration were depressed in SuHx-MVECs, and inhibiting mtROS, but not TRPV4, improved respiration in these cells. Collectively, our data show that, in SuHx-MVECs, mtROS production promotes TRPV4-mediated increases in [Ca2+]i, mitochondrial fission, and decreased mitochondrial respiration. These results suggest an important role for mtROS in driving MVEC dysfunction in PAH.

scholarly journals Distinct Types of Plexiform Lesions Identified by Synchrotron-Based Phase Contrast Micro-CT

2021 ◽  
Author(s):  
Christian Westöö ◽  
Christian Carl Norvik ◽  
Niccolò Peruzzi ◽  
Oscar van der Have ◽  
Goran Lovric ◽  
...  
Keyword(s):  
Pulmonary Arterial Hypertension ◽  
Arterial Hypertension ◽  
Phase Contrast ◽  
Pulmonary Veins ◽  
Pulmonary Arteries ◽  
Vasa Vasorum ◽  
Dimensional Structure ◽  
Micro Ct ◽  
Plexiform Lesions ◽  
Pulmonary Arterial

In pulmonary arterial hypertension, plexiform lesions are associated with severe arterial obstruction and right ventricular failure. Exploring their structure and position is crucial for understanding the interplay between hemodynamics and vascular remodeling. The aim of this research was to use synchrotron-based phase contrast micro-CT to study the three-dimensional structure of plexiform lesions. Archived paraffin-embedded tissue-samples from 14 patients with pulmonary arterial hypertension (13 idiopathic, 1 with known BMPR2-mutation) were imaged. Clinical data showed high median PVR (12,5 WU) and mPAP (68 mmHg). Vascular lesions with more than one lumen were defined as plexiform. Prior radiopaque dye injection in some samples facilitated 3D-rendering. Four distinct types of plexiform lesions were identified: (1) localized within or derived from monopodial branches (supernumerary arteries), often with connection to the vasa vasorum; (2) localized between pulmonary arteries and larger airways as a tortuous transformation of intrapulmonary bronchopulmonary anastomoses; (3) as spherical structures at unexpected abrupt ends of distal pulmonary arteries; and (4) as occluded pulmonary arteries with re-canalization. By appearance and localization, types 1-2 potentially relieve pressure via the bronchial circulation, as pulmonary arteries in these patients were almost invariably occluded distally. In addition, types 1-3 were often surrounded by dilated thin-walled vessels, often connected to pulmonary veins, peri-bronchial vessels or the vasa vasorum. Collaterals, by-passing completely occluded pulmonary arteries, were also observed to originate within plexiform lesions. In conclusion, synchrotron-based imaging revealed significant plexiform lesion heterogeneity, resulting in a novel classification. The four types likely have different effects on hemodynamics and disease progression.

Abstract 2618: Bone Morphogenic Protein-9 Stimulates Endothelin-1 Synthesis by Human Pulmonary Microvascular Endothelial Cells: A Possible Contributor to the Pathogenesis of Pulmonary Arterial Hypertension

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Greg P Star ◽  
Michele Giovinazzo ◽  
David Langleben
Keyword(s):  
Endothelial Cells ◽  
Pulmonary Arterial Hypertension ◽  
Arterial Hypertension ◽  
Microvascular Endothelial Cells ◽  
Tgf Beta ◽  
Endothelin 1 ◽  
Endothelial Proliferation ◽  
Pulmonary Arterial ◽  
Microvascular Endothelial ◽  
Alk 5

Pulmonary arterial hypertension (PAH) is thought to be related to progressive obliteration of the pulmonary microvasculature. Endothelial proliferation and dysfunction is a central process, and increased levels of the potent endothelial-derived vasoconstrictor and mitogen, endothelin-1 (ET-1) have been described. It is not known what triggers these increased ET-1 levels. With the description of mutations in receptors for bone morphogenic proteins (BMP) and other members of the TGF-beta family of proteins as causative events in hereditary forms of PAH, we hypothesized that BMPs might modulate ET-1 synthesis. Recently, BMP-9, which acts via the type-1 TGF-beta receptor activin-like kinase 1 (ALK-1), has been identified as a potent regulator of endothelial proliferation and migration. We therefore studied the effects of BMP-9 on ET-1 in-vitro production by human lung microvascular endothelial cells (HLMVEC), the cell implicated in the pathogenesis of PAH. HLMVEC were cultured to confluence in EGM-2MV medium and then BMP-9 (0 –100 ng/ml) was added to the medium for 24 and 48 hours. All concentrations increased ET-1 production at both time points, with 10 ng/ml resulting in a 99% increase versus controls at 24 hours and 104% at 48 hours (all p<0.001). Addition of SB-431542 (10 uM) a specific inhibitor of the kinase activity of ALK-5 significantly reduced the 48 hour ET-1 synthesis provoked by BMP-9, with a 41% decrease for 1 ng/ml BMP-9 but only a 9% reduction for 10 and 100ng/ml BMP-9. In conclusion, this is the first identification of BMP-9 as a potent stimulator of ET-1 production by HLMVEC. Although the actions of BMP-9 are thought to be through ALK-1, there may be a component of interaction with ALK-5, or ALK-5 may have cross-talk with ALK-1. ALK-5 inhibitors such as SB-431542 can reduce BMP-9 mediated ET-1 production and might ultimately have therapeutic benefit for PAH.

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