LDL phagocytosis by macrophages

LDL phagocytosis by macrophages is a multifaceted cellular process characterized by the internalization of low-density lipoprotein (LDL) particles, particularly in their oxidized form (oxLDL), from the sub-endothelial space of arterial walls. This uptake is primarily mediated by scavenger receptors such as CD36 and Scavenger Receptor Class A Member 1 (SR-A1), rather than the classic LDL receptor pathway which is typically downregulated in response to high intracellular cholesterol (Nature Reviews Cardiology, 2021). The excessive accumulation of lipid droplets within the macrophage leads to its transformation into a 'foam cell,' the pathological hallmark of atherosclerotic plaque initiation and progression (Cell, 2018). While macrophages initially internalize these lipids to clear them from the vessel wall, the eventual failure of cholesterol efflux mechanisms triggers a pro-inflammatory cascade and cell death, contributing to plaque instability and clinical events like myocardial infarction (Circulation, 2019). Current therapeutic strategies do not target the phagocytic process directly but instead focus on lowering the concentration of circulating LDL using statins or PCSK9 inhibitors to reduce the substrate available for macrophage uptake (Journal of Biological Chemistry, 2020). Emerging research is investigating the potential of specifically blocking scavenger receptors or enhancing macrophage efferocytosis to stabilize plaques (PubMed: 32421345).

Other names

Macrophage foam cell formationMacrophage LDL uptakeOxidized LDL endocytosisMacrophage-mediated lipid internalization

Drugs typically modulate this process by increasing the expression of hepatic Low-density lipoprotein receptors to lower circulating LDL levels or by reducing the systemic availability of lipid substrates, thereby indirectly limiting macrophage uptake and subsequent foam cell formation.