By comparing bone marrow-derived macrophages (BMDM) of wild-type (WT) and LDL receptor knockout (LDLr−/−) mice, we observed hypercholesterolemia increased the number of contact sites at mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs), enhanced mitochondrial hydrogen peroxide release, altered the gene expression of inflammatory markers, and increased oxidized LDL (ox-LDL) uptake and phagocytic activity. This evidence concerns the gene LDLR and familial hypercholesterolemia.