Abstract
We examined the role of prostaglandin D2 (PGD2) in the formation of E-selectin following inter-leukin-1 (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 E-selectin biosynthesis. We also used an anti-PGD2 antibody to examine whether an intracrine mechanism was involved in E-selectin production. PGD2 and E-selectin levels were determined by radio-immunoassay and enzyme- immunoassay, respectively. E-selectin mRNA was assessed by real-time RT-PCR. IL-1-stimulated E-selectin production by HUVEC was dose-dependently inhibited by authentic PGD2 at concentrations greater than 10–6 mol/L. L-PGDS gene-transfected HUVEC produced more PGD2 than HUVEC transfected with the reporter gene alone. IL-1 induced increases in E-selectin production in HUVEC transfected with the reporter genes alone. However, this effect was significantly attenuated in the case of IL-1 stimulation of HUVEC trans-fected with L-PGDS genes, and accompanied by an apparent suppression of E-selectin mRNA expression. Neutralization of extracellular PGD2 by anti-PGD2- specific antibody influenced neither E-selectin mRNA expression nor E-selectin biosynthesis. HUVEC transfected with L-PGDS genes showed increased PGD2 synthesis. This increase was associated with attenuation of both E-selectin generation and E-selectin mRNA expression. The results suggest that endogenous PGD2 decreases E-selectin synthesis and E-selectin mRNA expression, probably through an intracrine mechanism.
Highlights
Adhesion molecules play an important role in the development and progression of atherosclerosis
In order to test our hypothesis that lipocaline-type PGD2 synthase (L-PGDS)/ prostaglandin D2 (PGD2) protects the vascular wall against immune-related vascular injury, we examined the relationship between endogenous PGD2 and E-selectin expression by endothelial cells and attempted to reveal its intracellular mechanism mediated by PGD2 using L-PGDS genetransfected endothelial cells in culture
In order to assess the role of PGD2 receptor-mediated signal transduction in E-selectin expression, we studied changes in cyclic AMP (cAMP), a second messenger of PGD2 signal transduction in human umbilical vein endothelial cells (HUVEC) transfected with transporter gene alone
Summary
Adhesion molecules play an important role in the development and progression of atherosclerosis. PGD2 is synthesized in vascular components of atheromatous lesions including endothelial cells, macrophages, platelets, and mast cells [8] and lipocalin-type PGD2 synthase (L-PGDS) is demonstrated to occur in atheromatous lesions in the cardiovascular system [9]. These data strongly suggest that L-PGDS/PGD2 is upregulated in response to immune-related vascular lesions and in turn, the increase of L-PGDS/PGD2 is exerted to attenuate the progression of the arterial remodeling. We proposed the hypothesis that PGD2 regulates E-selectin expression in endothelial cells, thereby contributing to leukocyte adhesion, an integral component of the development of vascular injury. We examined whether the increases in intracellular PGD2 synthesis influenced E-selectin mRNA expression and E-selectin biosynthesis observed following interleukin-1b (IL-1) stimulation
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