Interaction between lipid droplets and endoplasmic reticulum in human atherosclerotic plaques

Lipid droplets (LDs) are intracellular organelles that are found in nearly all cell types, where they serve fundamental roles in lipid metabolism and energy homeostasis. Traditionally considered as simple lipid storage deposits, these dynamic and remarkable organelles have recently been implicated in a number of other cellular functions, ranging from protein storage and degradation to virus replication. Intracellular accumulation of LDs is also a hallmark feature of diverse human diseases including diabetes type II, obesity, hepatosteatosis, cancer, and atherosclerosis. LDs are highly motile and possess the capability to interact with a variety of cell organelles, such as the endoplasmic reticulum membranes, mitochondria, endosomes, and peroxisomes. To date, however, much remains to be learned regarding the existence and structure of these interactions in the cardiovascular system. The results presented herein demonstrate that in the foam cells of human atherosclerotic plaques, LDs are preferentially associated with ER membranes probably to form a lipid-buffer system that allows the storage of free fatty acids and reduces the risk of lipotoxicity.