Targeting the Notch Signaling Pathway to Treat Atherosclerosis

Atherosclerosis remains the principal underlying cause of myocardial infarction, ischemic stroke and peripheral artery disease, and its progression reflects a complex interplay between lipid accumulation, endothelial dysfunction, chronic vascular inflammation and maladaptive remodeling of the arterial wall. The Notch signaling pathway, an evolutionarily conserved juxtacrine communication system, has emerged as a central regulator of every cell type implicated in atherogenesis, including endothelial cells, vascular smooth muscle cells, monocytes/macrophages and T lymphocytes. Depending on the receptor-ligand pairing, the hemodynamic context and the cellular compartment involved, Notch signaling can be either atheroprotective or atherogenic, a duality that has complicated efforts to translate mechanistic insight into therapy. This review summarizes current knowledge of the molecular architecture of the Notch pathway in the vasculature, dissects its cell type-specific and stage-specific contributions to atherosclerotic plaque initiation, progression, calcification and destabilization, and critically appraises pharmacological strategies designed to modulate Notch activity, including γ-secretase inhibitors, ligand- and receptor-directed monoclonal antibodies, soluble decoy receptors, microRNA-based approaches and drug repurposing strategies such as statins. Particular attention is paid to the cardiovascular toxicities that have emerged from oncology trials of Notch pathway inhibitors, which illustrate both the pharmacological tractability and the narrow therapeutic window of this pathway. We conclude that Notch-directed therapy for atherosclerosis is mechanistically well justified but will require cell type-selective and context-selective delivery strategies to be clinically viable.