Exploring the Role of Hypusine Signaling in Vascular Smooth Muscle Cells for Mitigating Restenosis in Coronary Artery Disease

BACKGROUND: Post-surgical restenosis in patients with coronary artery disease (CAD) is a pathological vascular remodeling process characterized by neointimal hyperplasia, which is mainly driven by phenotypic switching of vascular smooth muscle cells toward a synthetic and proliferative state. This study investigated a novel signaling pathway to promote the proproliferative phenotype of vascular smooth muscle cells and contribute to the neointimal hyperplasia development. METHODS: Using comparative proteomic analysis and Western blotting, expression of hypusine signaling components was evaluated in human primary cultures of coronary artery smooth muscle cells isolated from controls and patients with CAD, as well as in 3 preclinical animal models of restenosis: rat carotid injury, mouse carotid ligation, and canine coronary artery bypass graft. CAD-coronary artery smooth muscle cell proliferation was assessed by Western blot and immunofluorescence with pharmacological (N1-guanyl-1,7-diaminoheptane) and molecular (shRNA) inhibitors of DHPS (deoxyhypusine synthase). The contribution of hypusine signaling to neointimal hyperplasia was investigated using both pharmacological and genetic approaches. In addition, human saphenous vein and human coronary artery tissue cultures were used to explore the translational potential of targeting hypusine signaling to prevent neointimal hyperplasia. RESULTS: All components of the hypusine pathway (eIF5A (eukaryotic translation initiation factor 5A), DOHH (deoxyhypusine hydroxylase), and DHPS were significantly overexpressed in CAD-coronary artery smooth muscle cells and in preclinical animal models of restenosis. Pharmacological and molecular inhibition of DHPS reduced eIF5A hypusination, vascular smooth muscle cell proliferation, and expression of ECM (extracellular matrix) proteins. Proteomic and KEGG (Kyoto Encyclopedia of Genes and Genomes) analyses demonstrated disruption of cell-cycle and DNA replication pathways, including a downregulation of TTK (threonine tyrosine kinase). Our findings suggest that TTK acts as a downstream effector of hypusine signaling, which partly mediates the proliferative effects observed in CAD-coronary artery smooth muscle cells. In vivo, pharmacological and smooth muscle cell-targeted inactivation of DHPS significantly reduced neointimal hyperplasia without adverse effects. Finally, ex vivo human tissue culture confirmed that N1-guanyl-1,7-diaminoheptane mitigates growth factor-induced vascular remodeling. CONCLUSIONS: Hypusine signaling is a critical regulator of vascular smooth muscle cell proliferation for neointimal hyperplasia. Inhibiting DHPS reduces vascular remodeling, making it a promising target for preventing restenosis after coronary interventions.