Etrinabdione (VCE-004.8), a B55α activator, promotes angiogenesis and arteriogenesis in critical limb ischemia

Abstract

ABSTRACTBackgroundVasculogenic therapies explored for the treatment of peripheral artery disease (PAD) have encountered minimal success in clinical trials. Addressing this, B55α, an isoform of protein phosphatase 2A (PP2A), emerges as pivotal in vessel remodeling through activation of hypoxia-inducible factor 1α (HIF-1α). This study delves into the pharmacological profile of VCE-004.8 (Etrinabdione) and evaluates its efficacy in a preclinical model of critical limb ischemia, with a focus on its potential as a PP2A/B55α activator to induce angiogenesis and arteriogenesis.MethodsVascular endothelial cells were used forin vitroexperiments. Aorta ring assay was performed to explore sprouting activity. Matrigel plug-in assay was used to assess the angiogenic potential. Critical limb ischemia (CLI) in mice was induced by double ligation in the femoral arteria. Endothelial vascular and fibrotic biomarkers were studied by immunohistochemistry and qPCR. Arteriogenesis was investigated by microvascular casting and micro-CT. Proteomic analysis in vascular tissues was analyzed by LC-MS/MS.Ex-vivoexpression of B55α and biomarkers were investigated in artery samples from PAD patients.ResultsVCE-004.8 exhibited the ability to induce B55α expression and activate the intersecting pathways B55α/AMPK/Sirtuin 1/eNOS and B55α/PHD2/HIF-1α. VCE-004.8 prevented OxLDL and H2O2-induced cytotoxicity, senescence, and inflammation in endothelial cells. Oral VCE-004.8 increased aorta sproutingin vitroand angiogenesisin vivo. In CLI mice VCE-004.8 improved collateral vessel formation and induced endothelial cells proliferation, angiogenic gene expression and prevented fibrosis. The expression of B55α, Caveolin 1 and Sirtuin-1 is reduced in arteries from CLI mice and PAD patient, and the expression of these markers was restored in mice treated with VCE-004.8.ConclusionsThe findings presented in this study indicate that Etrinabdione holds promise in mitigating endothelial cell damage and senescence, while concurrently fostering arteriogenesis and angiogenesis. These observations position Etrinabdione as a compelling candidate for the treatment of PAD, and potentially other cardiovascular disorders.Novelty and SignificanceWhat Is Known?The phosphatase PPA2/B55α stabilizes endothelial cells (ECs) in response to cell stress conditions, thereby protecting ECs from apoptosis and promoting angiogenesis.Etrinabdione (VCE-004.8) functions as a potent activator of PPA2/B55α inducing PHD2 dephosphorylation at ser125 and fostering HIF activation.VCE-004.8 prevents vascular damage in preclinical models of systemic and cardiac fibrosis and alleviates blood-brain barrier disruption in neuroinflammatory conditions.VCE-004.8 is also a dual agonist of PPARγ and CB2receptors and shows antiinflammatory activity.Oral VCE-004.8 has meet the primary endpoints of safety and tolerability in a Phase IIa clinical trial with systemic sclerosis patients (clinicaltrial.gov:NCT03745001).What New Information Does This Article Contribute?Etrinabdione induces HIF-1α expression in endothelial cells through a novel pathway that potentially involves two axes: B55α/PHD2 and B55α/AMPK/Sirt1 signaling that may converge on HIF stabilization.Etrinabdione prevented endothelial cell damage and senescence, while inducing arteriogenesis and angiogenesis in CLI mice.In arteries of patients with PAD and in CLI mouse models, the expression levels of B55α, Caveolin 1, and Sirtuin 1 are diminished. However, treatment with Etrinabdione specifically in CLI mice prompts an increase in the levels of these proteins.Etrinabdione triggers neovascularization and angiogenesis specifically within hypoxic tissue in a critical ischemia model, with no impact on healthy tissue.