Disrupted PI3K subunit p110α signaling protects against pulmonary hypertension and reverses established disease in rodents
Eva M. Berghausen, … , Ralph T. Schermuly, Stephan Rosenkranz
Eva M. Berghausen, … , Ralph T. Schermuly, Stephan Rosenkranz
Published October 1, 2021
Citation Information: J Clin Invest. 2021;131(19):e136939. https://doi.org/10.1172/JCI136939.
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Research Article Cell biology Vascular biology

Disrupted PI3K subunit p110α signaling protects against pulmonary hypertension and reverses established disease in rodents

Abstract

Enhanced signaling via RTKs in pulmonary hypertension (PH) impedes current treatment options because it perpetuates proliferation and apoptosis resistance of pulmonary arterial smooth muscle cells (PASMCs). Here, we demonstrated hyperphosphorylation of multiple RTKs in diseased human vessels and increased activation of their common downstream effector phosphatidylinositol 3′-kinase (PI3K), which thus emerged as an attractive therapeutic target. Systematic characterization of class IA catalytic PI3K isoforms identified p110α as the key regulator of pathogenic signaling pathways and PASMC responses (proliferation, migration, survival) downstream of multiple RTKs. Smooth muscle cell–specific genetic ablation or pharmacological inhibition of p110α prevented onset and progression of pulmonary hypertension (PH) as well as right heart hypertrophy in vivo and even reversed established vascular remodeling and PH in various animal models. These effects were attributable to both inhibition of vascular proliferation and induction of apoptosis. Since this pathway is abundantly activated in human disease, p110α represents a central target in PH.

Authors

Eva M. Berghausen, Wiebke Janssen, Marius Vantler, Leoni L. Gnatzy-Feik, Max Krause, Arnica Behringer, Christine Joseph, Mario Zierden, Henrik ten Freyhaus, Anna Klinke, Stephan Baldus, Miguel A. Alcazar, Rajkumar Savai, Soni Savai Pullamsetti, Dickson W.L. Wong, Peter Boor, Jean J. Zhao, Ralph T. Schermuly, Stephan Rosenkranz

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Figure 6

Therapeutic inhibition of p110α reverses Su/Hx-induced pulmonary hypertension.

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Therapeutic inhibition of p110α reverses Su/Hx-induced pulmonary hyperte...
(A) Schematic diagram illustrating the treatment protocol in the Su/Hx model. (B) Double-immunostaining for vWF (brown) and α-smooth muscle actin (purple) demonstrating the muscularization (left panel) of peripheral pulmonary arteries or Van Gieson staining demonstrating medial wall thickness (right panel) in control animals versus untreated or PIK75-treated Su/Hx-induced pulmonary hypertension. Shown are representative images of lung sections. Scale bar: 100 μm. (C) Impact of p110α inhibition with PIK75 on vascular muscularization of small pulmonary arteries (<50 μm) from animals as indicated. Shown is the percentage of fully (M), partially (P), and nonmuscularized (N) vessels (at least 80 were analyzed per animal), n = 5, 6, 6. (D) Medial wall thickness of less than 50 μm pulmonary arteries, n = 5, 6, 6; (E) RVSP (mmHg), n = 5, 5, 6; (F) RV hypertrophy expressed as RV/LV + S ratio, n = 5, 6, 6. (G) Representative immunofluorescence photo-micrographs of PCNA (red) and DAPI (blue) in small pulmonary vessels from rats (scale bar: 20 μm, arrowheads indicate PCNA-positive cells) (left panel) and quantification of proliferating cells (right panel). Shown are PCNA-positive cells per total cells from 10 representative vessels, randomized to 200 cells, n = 9, 6, 6. (H) Immunofluorescence staining of TUNEL (green) and DAPI (blue) in small pulmonary vessels (scale bar: 20 μm, arrowheads indicate TUNEL-positive cells) (left panel) and quantification of apoptotic cells (right panel). Shown are TUNEL-positive cells per total cells from 10 representative vessels, randomized to 100 cells, n = 5, 6, 6. All data represent mean ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001 as assessed by ANOVA followed by a Newman-Keuls post hoc test.