Premium
Afamin is synthesized by cerebrovascular endothelial cells and mediates α‐tocopherol transport across an in vitro model of the blood–brain barrier
Author(s) -
Kratzer Ingrid,
Bernhart Eva,
Wintersperger Andrea,
Hammer Astrid,
Waltl Sabine,
Malle Ernst,
Sperk Günther,
Wietzorrek Georg,
Dieplinger Hans,
Sattler Wolfgang
Publication year - 2009
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2008.05796.x
Subject(s) - blood–brain barrier , in vitro , tocopherol , chemistry , endothelial stem cell , endothelium , biophysics , microbiology and biotechnology , neuroscience , biochemistry , biology , medicine , central nervous system , vitamin e , antioxidant
Abstract α‐Tocopherol (αTocH), a member of the vitamin E family, is essential for normal neurological function. Despite the importance of αTocH transport into the CNS, transfer mechanisms across the blood–brain barrier (BBB) are not entirely clear. We here investigate whether afamin, a known αTocH‐binding protein, contributes to αTocH transport across an in vitro model of the BBB consisting of primary porcine brain capillary endothelial cells (BCEC) and basolaterally cultured astrocytoma cells. Exogenously added afamin had no adverse effects on BCEC viability or barrier function and was transported across BCEC Transwell cultures. Furthermore, αTocH transport across polarized BCEC cultures to astrocytoma cells is facilitated by afamin, though to a lesser extent than by high‐density lipoprotein‐mediated transport, an essential and in vivo operating αTocH import pathway at the cerebrovasculature. We also demonstrate that porcine BCEC endogenously synthesize afamin. In line with these in vitro findings, afamin was detected by immunohistochemistry in porcine, human postmortem, and mouse brain, where prominent staining was observed almost exclusively in the cerebrovasculature. The demonstration of afamin mRNA expression in isolated brain capillaries suggests that afamin might be a new family member of binding/transport proteins contributing to αTocH homeostasis at the BBB in vivo .