TLR9 and familial hypercholesterolemia: Macrophages containing elevated levels of cholesterol, e.g., in abca1 knockdown cells or in hypercholesterolemia not only contain higher levels of TLR4 and TLR9, but are also hyper-responsive to lipopolysaccharide as well as to TLR2, TLR7, and TLR9 agonists (Tall and Yvan-Charvet, 2015).