Disrupted PI3K subunit p110α signaling protects against pulmonary hypertension and reverses established disease in rodents
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
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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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 1

Multiple growth factors contribute to PAH and hPASMC proliferation.

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Multiple growth factors contribute to PAH and hPASMC proliferation. (A) ...
(A) Representative immunohistochemical staining showing phosphorylation of the indicated RTKs in lung tissue from healthy donors and patients with idiopathic PAH (n = 4 each). Scale bar: 50 μm. (B) Immunofluorescent staining demonstrating phosphorylation of PDGFβ receptor in the media of pulmonary arteries/arterioles from patients with PAH (n = 4; for control staining, see Supplemental Figure 1). Scale bar: 50 μm. (C–F) Proliferative response (BrdU incorporation) of hPASMCs to various growth factors and inhibition by the tyrosine kinase inhibitor imatinib. Quiescent cells were stimulated with either PDGF-BB (C), various growth factors as indicated (D), smooth muscle basal medium (SmBm: FGF [2 ng/mL], EGF [0.5 ng/mL], insulin [0.5 μg/mL], FCS [5%]) alone or with PDGF-BB (30 ng/mL), subsequently referred to as growth factor mixture (GFM) (E), and GFM (F), as indicated. In C and F, cells were preincubated with the indicated concentrations of imatinib for 30 minutes. Data were normalized to starved controls and represent mean ± SEM. *P < 0.05; ****P < 0.0001 as assessed by 1-way ANOVA with Dunnett’s test (n = 7–10 in each group).