Fructose-1,6-bisphosphate (FBP), a glycolytic intermediate, has neuroprotective effects in various brain injury models. However, its effects on blood-brain barrier (BBB) are largely unknown. In this study, we investigated the effects of FBP on lipopolysaccharide (LPS)-induced BBB dysfunction in in vitro BBB model comprising co-culture of mouse brain endothelial cell line, bEnd.3 and mouse primary astrocyte and explored its action mechanism therein involved. LPS induced the impairment of endothelial permeability and transendothelial electrical resistance (TEER). The functional changes were confirmed by alterations in immunostaining for junctional proteins occludin, ZO-1 and VE-cadherin, such as the loss of cortical staining pattern and appearance of intercellular gaps in endothelial cells. Co-administration of FBP alleviated the deleterious effects of LPS on BBB permeability and TEER in a dose dependent manner. And also FBP inhibited the LPS-induced changes in the distribution of endothelial junctional proteins, resulting in the better preservation of monolayer integrity. FBP suppressed the production of reactive oxygen species (ROS) but did not affect cyclooxygenase-2 expression and prostaglandin E₂ production in endothelial cells stimulated with LPS. Taken together, these data suggest that FBP could ameliorate LPS-induced BBB dysfunction through the maintenance of junctional integrity, which might be mediated by downregulation of ROS production.

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Increased leukocyte adhesion and infiltration under various pathological conditions is accompanied by increased expression of endothelial ICAM‐1 and the blockade of ICAM‐1 ligation limits leukocyte infiltration and brain damage. PGE2 is known to be the principal pro‐inflammatory prostanoid and play important roles in brain diseases through binding to EP1‐4 receptors. However, there have been contradictory reports on its actions during inflammation processes, especially in vascular endothelial cells. In this study, we investigated the roles of PGE2 in the expression of ICAM‐1 in bEnd.3 cells and therein involved signaling pathways. We investigated that elevation of cAMP is necessary for PGE2‐induced ICAM‐1 expression in bEnd.3 cells. We determined effect of PGE2 on Epac activation using Rap1‐GTP pull down assay and effect of Epac on PI3K/Akt activation as well as ICAM‐1 expression. Next, we showed that loss of Akt activity results in inhibition of PGE2‐induced NF‐κB activation. On the other hand, interestingly enough, PKA inhibitor stimulated Akt phosphorylation and ICAM‐1 expression and specific activator inhibited PGE2‐induced ICAM‐1 expression and Akt phosphorylation. Taken together, these data suggest that this antagonism between PKA and Epac signaling is importantly involved in the regulation of PI3K/Akt signaling axis, and thereby ICAM‐1 expression in cerebrovascular endothelial cells.This study was supported by grants from Ajou University School of Medicine and Gyunggi‐do through CCRB‐GRRC