Endogenous prostaglandin D2 synthesis decreases vascular cell adhesion molecule-1 expression in human umbilical vein endothelial cells

We examined the role of prostaglandin D2 (PGD2) in the expression of vascular cell adhesion molecule-1 (VCAM)-1 following interleukin-1β (IL-1) stimulation in human umbilical vein endothelial cells (HUVEC) transfected with lipocaline-type PGD2 synthase (L-PGDS) genes. HUVEC were isolated from human umbilical vein and incubated with 20 U/ml IL-1 and various concentrations of authentic PGD2. The isolated HUVEC were also transfected with L-PGDS genes by electroporation. The L-PGDS-transfected HUVEC were used to investigate the role of endogenous PGD2 in IL-1-stimulated VCAM-1 biosynthesis. We also used an anti-PGD2 antibody to examine whether an intracrine mechanism was involved in VCAM-1 production. PGD2 and VCAM-1 levels were determined by radio- and cell surface enzyme-immunoassay, respectively. VCAM-1 mRNA was assessed by RT-PCR. IL-1-stimulated VCAM-1 expression by HUVEC was dose-dependently inhibited by authentic PGD2. L-PGDS gene-transfected HUVEC produced more PGD2 than HUVEC transfected with the reporter gene alone. IL-1 induced increases in VCAM-1 expression in HUVEC transfected with reporter genes alone. However, this effect was significantly attenuated in the case of IL-1 stimulation of HUVEC transfected with L-PGDS genes, and accompanied by an apparent suppression of VCAM-1 mRNA expression. Neutralization of extracellular PGD2 by anti-PGD2-specific antibody influenced neither VCAM-1 mRNA expression nor VCAM-1 biosynthesis. In conclusion, HUVEC transfected with L-PGDS genes showed increased PGD2 synthesis. This increase was associated with attenuation of both VCAM-1 expression and VCAM-1 mRNA expression. The results suggest that endogenous PGD2 decreases VCAM-1 expression and VCAM-1 mRNA expression, probably through an intracrine mechanism.