Novel Tryptophan Hydroxylase Inhibitor TPT-001 Reverses PAH, Vascular Remodeling, and Proliferative-Proinflammatory Gene Expression

Ekaterina Legchenko; Philippe Chouvarine; Fatimunnisa Qadri; Edgar Specker; Marc Nazaré; Radoslaw Wesolowski; Susann Matthes; Michael Bader; Georg Hansmann

doi:10.1016/j.jacbts.2024.04.006

Novel Tryptophan Hydroxylase Inhibitor TPT-001 Reverses PAH, Vascular Remodeling, and Proliferative-Proinflammatory Gene Expression

JACC Basic Transl Sci. 2024 Jun 5;9(7):890-902. doi: 10.1016/j.jacbts.2024.04.006. eCollection 2024 Jul.

Authors

Ekaterina Legchenko¹, Philippe Chouvarine¹, Fatimunnisa Qadri², Edgar Specker^{3

4}, Marc Nazaré³, Radoslaw Wesolowski^{2

4}, Susann Matthes², Michael Bader^{2

4

5

6

7}, Georg Hansmann^{1

8}

Affiliations

¹ Department of Pediatric Cardiology and Critical Care, Hannover Medical School, Hannover, Germany.
² Max-Delbrück-Center for Molecular Medicine, Berlin, Germany.
³ Chemical Biology Platform, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin-Buch, Germany.
⁴ Trypto Therapeutics GmbH, Berlin, Germany.
⁵ German Center for Cardiovascular Research, Partner Site Berlin, Berlin, Germany.
⁶ Charité Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany.
⁷ Institute for Biology, University of Lübeck, Lübeck, Germany.
⁸ Department of Pediatric Cardiology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany.

Abstract

The serotonin pathway has long been proposed as a promising target for pulmonary arterial hypertension (PAH)-a progressive and uncurable disease. We developed a highly specific inhibitor of the serotonin synthesizing enzyme tryptophan hydroxylase 1 (TPH1), TPT-001 (TPHi). In this study, the authors sought to treat severe PAH in the Sugen/hypoxia (SuHx) rat model with the oral TPHi TPT-001. Male Sprague Dawley rats were divided into 3 groups: 1) ConNx, control animals; 2) SuHx, injected subcutaneously with SU5416 and exposed to chronic hypoxia for 3 weeks, followed by 6 weeks in room air; and 3) SuHx+TPHi, SuHx animals treated orally with TPHi for 5 weeks. Closed-chest right- and left heart catheterization and echocardiography were performed. Lungs were subject to histologic and mRNA sequencing analyses. Compared with SuHx-exposed rats, which developed severe PAH and right ventricular (RV) dysfunction, TPHi-treated SuHx rats had greatly lowered RV systolic (mean ± SEM: 41 ± 2.3 mm Hg vs 86 ± 6.5 mm Hg; P < 0.001) and end-diastolic (mean ± SEM: 4 ± 0.7 mm Hg vs 14 ± 1.7 mm Hg; P < 0.001) pressures, decreased RV hypertrophy and dilation (all not significantly different from control rats), and reversed pulmonary vascular remodeling. We identified perivascular infiltration of CD3⁺ T cells and proinflammatory F4/80⁺ and CD68⁺ macrophages and proliferating cell nuclear antigen-positive alveolar epithelial cells all suppressed by TPHi treatment. Whole-lung mRNA sequencing in SuHx rats showed distinct gene expression patterns related to pulmonary arterial smooth muscle cell proliferation (Rpph1, Lgals3, Gata4), reactive oxygen species, inflammation (Tnfsrf17, iNOS), and vasodilation (Pde1b, Kng1), which reversed expression with TPHi treatment. Inhibition of TPH1 with a new class of drugs (here, TPT-001) has the potential to attenuate or even reverse severe PAH and associated RV dysfunction in vivo by blocking the serotonin pathway.

Keywords: drug discovery; pulmonary arterial hypertension; serotonin; tryptophan hydroxylase inhibitor.