TY - JOUR
T1 - Ether lipid transfer across the blood-brain and placental barriers does not improve by inactivation of the most abundant ABC transporters
AU - Dorninger, Fabian
AU - Vaz, Frédéric M.
AU - Waterham, Hans R.
AU - Klinken, Jan B. van
AU - Zeitler, Gerhard
AU - Forss-Petter, Sonja
AU - Berger, Johannes
AU - Wiesinger, Christoph
N1 - Funding Information: The authors thank Martina Rothe for excellent technical support. This study was conducted in the framework of the ERA-Net for Research Programmes on Rare Diseases (E-Rare; project acronym “PERescue”) and was funded by grants from the Austrian Science Fund (FWF; P24843-B24 , I2738-B26 , P31082-B21 and P34723 ). The authors sincerely thank RhizoKids International for additional support. Publisher Copyright: © 2022 The Authors
PY - 2022/10/15
Y1 - 2022/10/15
N2 - 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.
AB - 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.
KW - ATP-binding cassette transporter
KW - Alzheimer's disease
KW - Blood-brain barrier
KW - Peroxisome
KW - Plasmalogen
KW - Precursor supplementation
UR - http://www.scopus.com/inward/record.url?scp=85136537453&partnerID=8YFLogxK
U2 - https://doi.org/10.1016/j.brainresbull.2022.08.006
DO - https://doi.org/10.1016/j.brainresbull.2022.08.006
M3 - Article
C2 - 35981629
SN - 0361-9230
VL - 189
SP - 69
EP - 79
JO - Brain research bulletin
JF - Brain research bulletin
ER -