Endothelial gateways for brain lipid uptake and metabolism.

Lipids, which constitute half of the brain's solid matter, are essential for forming specialized membranes of neural cells, providing energy sources, and facilitating cell-to-cell communication. Although the blood-brain barrier restricts lipid movement between peripheral circulation and the brain, multiple mechanisms supply the building blocks necessary to synthesize the diverse lipid species present in the central nervous system (CNS). In this issue of the JCI, Song et al. characterize specialized microvascular niches that metabolize circulating triglyceride-rich lipoproteins (TRLs) to deliver fatty acids into the brain. They located GPIHBP1, an essential chaperone for lipoprotein lipase (LPL) in the fenestrated endothelial cells of the choroid plexus (ChP) and circumventricular organs (CVOs), demonstrating lipolytic processing of peripheral TRLs and brain uptake of fatty acids. This advance implicates the GPIHBP1/LPL lipid metabolic hub in supporting the roles of the ChP and CVO in cerebrospinal fluid composition, immunity, satiety, thirst, and metabolic homeostasis.