and does

Phospholipid transport from the periphery to the brain is an understudied topic. When certain lipid species are deficient due to impaired synthesis, though, transfer across the blood-brain barrier is essential for replenishing lipids in the brain. For example, the deficiency in plasmalogens, the most abundant ether lipids in mammals, has detrimental effects on the brain, which is a major issue in inherited peroxisomal disorders but also contributes to more common disorders like Alzheimer’s disease. Oral administration of alkylglycerols like batyl alcohol, which carry a pre-formed ether bond, enables replenishment of ether lipids in various peripheral tissues. However, plasmalogen deficiency in the brain cannot be overcome by this approach. Here, we tried to increase cerebral plasmalogen uptake by modulating the efflux transport across the blood-brain barrier. We hypothesized, based on previous literature, that at least some ether lipid species readily enter endothelial cells of the barrier through the transporter MFSD2A but are re-exported by ATP-binding cassette (ABC) transporters. By crossbreeding Mdr1a -/- /Mdr1b -/- /Bcrp -/- and ether lipid-deficient Gnpat -/- mice as well as pharmacological inhibition with MK-571 to inactivate the major ABC transporters at the blood-brain barrier, we evaluated the potential of combined ABC transporter inhibition and oral batyl alcohol administration for the treatment of plasmalogen deficiency. We found that even in the absence of the most abundant ABC transporters, batyl alcohol supplementation did not restore plasmalogen levels in the brain, despite the presence of a wide spectrum of ether lipid subspecies in the plasma as demonstrated by lipidomic analysis. Surprisingly, batyl alcohol treatment of pregnant Gnpat +/- dams had beneficial effects on the plasmalogen levels of Gnpat -/- offspring with defective ether lipid biosynthesis, independently of ABC transporter status at the placental barrier. Our results underline the autonomy of brain lipid homeostasis and indicate that peripheral supplementation of ether lipids is not sufficient to supply the brain with larger amounts of plasmalogens. Yet, the findings suggest that alkylglycerol treatment during pregnancy may pose a viable option to ameliorate some of the severe developmental defects of inborn ether lipid deficiency. original hypothesis, the data add important information to our understanding of ether lipid supply of the brain and should be considered, when developing treatment approaches aiming at a modulation of brain plasmalogen levels. On the one hand, transfer of peripheral ether lipids to the brain occurs only to a very low extent, even when reverse transport at the blood-brain barrier is prevented. On the other hand, we show that increasing the availability of ether lipids in pregnant dams enables the transmission of limited amounts of these lipids to the developing embryo. Our results may have important implications for the treatment of inborn ether lipid deficiency but also for more common disorders involving alterations of ether lipid levels, like Alzheimer’s disease. Furthermore, they substantiate the importance of brain-autonomous ether lipid biosynthesis and the brain’s independence from exogenous ether lipid supply thus adding an important puzzle piece to our understanding of brain lipid homeostasis. LPC-P, ether-linked lysophosphatidylcholine; lysophosphatidylethanolamine; ether-linked lysophosphatidylethanolamine; ether-linked phosphatidylcholine; ether-linked phosphatidylethanolamine; phosphatidylethanolamine