TLR4 and endothelial dysfunction: For instance, lipopolysaccharide (LPS) activates Toll-like receptor 4 (TLR4) in endothelial cells, triggering a series of interactions within signaling pathways, including the nicotinamide adenine dinucleotide phosphate oxidase/reactive oxygen species (ROS)/endothelial nitric oxide synthase pathway, ultimately leading to endothelial dysfunction (Grylls et al., 2021).