Koji Kobayashi, Y. Tsubosaka, M. Hori
Mar 1, 2013
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Arteriosclerosis, Thrombosis, and Vascular Biology
Abstract
Objective—Prostaglandin D2 (PGD2) is one of the prostanoids produced during inflammation. Although PGD2 is known to decrease endothelial permeability through D prostanoid (DP) receptor stimulation, the detailed mechanism is unknown. Methods and Results—Treatment with PGD2 (0.1–3 &mgr;mol/L) or the DP receptor agonist, BW245C (0.1–3 &mgr;mol/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 &mgr;mol/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 &mgr;g) 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—PGD2-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.