Prostaglandin D 2 -DP Signaling Promotes Endothelial Barrier Function via the cAMP/PKA/Tiam1/Rac1 Pathway

Abstract

Objective— Prostaglandin D 2 (PGD 2 ) is one of the prostanoids produced during inflammation. Although PGD 2 is known to decrease endothelial permeability through D prostanoid (DP) receptor stimulation, the detailed mechanism is unknown. Methods and Results— Treatment with PGD 2 (0.1–3 μmol/L) or the DP receptor agonist, BW245C (0.1–3 μmol/L), dose-dependently increased transendothelial electrical resistance and decreased the FITC-dextran permeability of human umbilical vein endothelial cells. Both indicated decreased endothelial permeability. These phenomena were accompanied by Tiam1/Rac1-dependent cytoskeletal rearrangement. BW245C (0.3 μmol/L) increased the intracellular cAMP level and subsequent protein kinase A (PKA) activity. Pretreatment with PKA inhibitory peptide, but not gene depletion of exchange protein directly activated by cAMP 1 (Epac1), attenuated BW245C-induced Rac1 activation and transendothelial electric resistance increase. In vivo, application of 2.5% croton oil or histamine (100 μg) caused vascular leakage indexed by dye extravasation. Pretreatment with BW245C (1 mg/kg) attenuated the dye extravasation. Gene deficiency of DP abolished, or inhibition of PKA significantly reduced, the DP-mediated barrier enhancement. Conclusion— PGD 2 -DP signaling reduces vascular permeability both in vivo and in vitro. This phenomenon is mediated by cAMP/PKA/Tiam1-dependent Epac1–independent Rac1 activation and subsequent enhancement of adherens junction in endothelial cell.