Glial contribution to cyclodextrin-mediated reversal of cholesterol accumulation in murine NPC1-deficient neurons in vivo
Niemann-Pick type C (NPC) disease is a rare and fatal lysosomal storage disorder presenting severe neurovisceral symptoms. Disease-causing mutations in genes encoding either NPC1 or NPC2 protein provoke accumulation of cholesterol and other lipids in specific structures of the endosomal-lysosomal system and degeneration of specific cells, notably neurons in the central nervous system (CNS). 2-hydroxypropyl-beta-cyclodextrin (CD) emerged as potential therapeutic approach based on animal studies and clinical data, but the mechanism of action on neurons has remained unclear. To address this topic in vivo, we took advantage of the retina as highly accessible part of the (CNS) and intravitreal injections as mode of drug administration. We find that CD enters the endosomal-lysosomal system of neurons and enables the release of lipid-laden lamellar inclusions, which are then removed from the extracellular space by specific types of glial cells. Thus, CD triggers a concerted action of neurons and glial cells to restore lipid homeostasis in the central nervous system.