Endothelial inflammation refers to the activation and dysfunction of vascular endothelial cells in response to harmful stimuli (e.g., oxidized lipids, cytokines, infectious agents, or mechanical stress), leading to: Increased expression of adhesion molecules (e.g., VCAM-1, ICAM-1, E-selectin) Leukocyte recruitment and infiltration into the vascular wall Proinflammatory cytokine and chemokine release Loss of endothelial barrier function Pro-thrombotic and pro-oxidative state This process is a key early event in the pathogenesis of atherosclerosis, promoting the transition from a healthy vascular endothelium to a chronically inflamed, dysfunctional surface that facilitates plaque development and progression.