Figure 1.

Initiation and progression of atherosclerosis Monocytes enter the damaged subendothelial under the action of chemokines and adhesion molecules and differentiate into macrophages. Macrophages engulf lipid particles in the endothelium and become foam cells, forming streak, an early lesion of atherosclerosis. Smooth muscle cells acquire macrophage properties and phagocytose lipids, constituting another source of foam cells. Smooth muscle cells produce collagen to form fibrous caps. The toxicity of cholesterol leads to the apoptosis of foam cells, and macrophages remove the apoptotic cells by efferocytosis. Inadequate efferocytosis enlarged lipid cores.