Levosimendan Ameliorates Adverse Pulmonary Vascular Remodeling in Group-2 Pulmonary Hypertension.

AimsPulmonary hypertension (PH) due to left heart disease (Group-2PH) is the most common form of PH and comprises two distinct subtypes: isolated post-capillary-PH (IpcPH) and combined post-and pre-capillary-PH (CpcPH). Despite its high prevalence and poor prognosis, no targeted therapies are currently approved, largely due to the absence of reliable preclinical models that recapitulate these human hemodynamic phenotypes. Levosimendan, a calcium sensitizer with inotropic and vasodilatory properties, has shown promise in early clinical trials for Group-2PH, but its mechanisms of action remain unclear. This study aimed to develop and validate experimental models of IpcPH and CpcPH and to assess the therapeutic effects of levosimendan on pulmonary vascular remodeling, inflammation, and cardiac function to support ongoing clinical translation. Methods and ResultsIn a multicentre preclinical study, we established two rodent models that faithfully replicate the human IpcPH and CpcPH hemodynamic profiles. CpcPH animals exhibited severe pulmonary vascular remodeling, inflammatory cell infiltration, and a distinct pro-proliferative transcriptomic signature, whereas IpcPH animals showed minimal pulmonary vascular involvement. Levosimendan (3 mg/kg/day, 3 weeks) improved biventricular function and pulmonary hemodynamics in both models. In CpcPH, levosimendan additionally reduced pulmonary vascular remodeling, attenuated inflammation, and partially reversed disease-associated transcriptomic reprogramming. Transcription factor enrichment analysis identified NF-{kappa}B as a key upstream regulator inhibited by treatment. In a translational extension, nine circulating inflammation-related-proteins differentiated CpcPH from IpcPH patients; among them, TNF, IL-12B, 4E-BP1, NT-3, NGF, FGF21, and FGF23 predicted poor survival. IL-18 and 4E-BP1 were elevated in CpcPH lungs and decreased following levosimendan treatment. ConclusionsInflammation is a major contributor to adverse pulmonary vascular remodeling in CpcPH. Levosimendan improves cardiac performance and mitigates pulmonary vascular inflammation and remodeling, supporting its potential as a dual-action therapeutic agent in Group-2PH. These findings validate novel preclinical models and provide mechanistic evidence reinforcing ongoing clinical evaluation of levosimendan in this condition. Translational perspectiveGroup-2 PH lacks targeted therapies, partly due to the absence of validated preclinical models. We validated models recapitulating human IpcPH and CpcPH and identified inflammation as a key driver of pulmonary vascular remodeling in CpcPH. Levosimendan improved biventricular function and reduced vascular remodeling and inflammation through NF-{kappa}B inhibition. Circulating IL-18 and 4E-BP1 reflected disease severity and treatment response. These findings establish robust translational models, reveal inflammatory mechanisms underlying CpcPH, and provide mechanistic evidence supporting ongoing clinical trials of levosimendan as a dual-action therapeutic strategy in Group-2 PH.