Arachidonic acid increases permeability of HBMEC monolayers via increased production of prostaglandin E2

Abstract

The blood‐brain barrier, formed by microvessel endothelial cells, is the restrictive barrier between the brain parenchyma and the circulating blood. Arachidonic acid (AA) is a conditionally essential polyunsaturated fatty acid [20:4(n‐6)] and a major constituent of brain lipids. In this study transport of AA in confluent monolayers of human brain microvessel endothelial cells (HBMEC) was examined. Addition of [3H]AA to the apical compartment of HBMEC confluent monolayers cultured on Transwell® inserts resulted in rapid incorporation of [3H]AA into the basolateral medium. Knock down of FATP‐1 or CD36 did not alter [3H]AA movement into the basolateral medium and this was due to a rapid generation of prostaglandin E2 (PGE2), an eicosanoid known to facilitate opening of the blood‐brain barrier. Disruption of HBMEC monolayers following AA exposure was confirmed by an increased movement of fluorescein‐labeled dextran from the apical to basolateral medium. HBMECs expressed PGE2 synthase, cyclooxygenase‐1 and ‐2, PGE2 receptors, tight junction proteins and prostaglandin transporters. Specific cyclooxygenase‐2 inhibitors attenuated the AA‐mediated increase in membrane permeability. The results indicate that AA increases the permeability of HBMEC monolayers via increased production of PGE2. [Funded by NSERC Canada; GMH is a Canada Research Chair in Molecular Cardiolipin Metabolism]