Substance P-induced cyclooxygenase-2 expression in human umbilical vein endothelial cells

Abstract

1 Substance P (SP) is a neuropeptide involved in neurogenic inflammation and an agonist for NK 1, NK 2, and NK 3 receptors. SP induces prostaglandin (PG) production in various cell types, and these eicosanoids are responsible for numerous inflammatory and vascular effects. 2 Cyclooxygenase (COX) are needed to convert arachidonic acid to PGs. The study evaluated the effect of SP on COX expression in human umbilical vein endothelial cells (HUVEC). 3 COX-2 protein expression was upregulated by SP with a peak at 100 nM and at 20 h; in the same experimental conditions COX-1 protein expression was unchanged. A correlation between COX-2 expression and PGI 2 and PGE 2 release was detected. 4 Dexamethasone (DEX) inhibited SP-mediated COX-2 expression. Mitogen-activated protein kinases (MAPK) p38 and p42/44 were activated by SP, whereas SB202190 and PD98059, inhibitors of these kinases, blocked COX-2 expression. 5,5-dimethyl-3-(3-fluorophenyl)-4-(4- methylsulphonyl)phenyl-2(5H)-furanone (DFU), an experimental selective COX-2 inhibitor, blocked SP-induced PG release. 5 By RT-PCR and Western blot analysis, we demonstrated that NK 1 and NK 2 but not NK 3 receptors are present on HUVEC. Selective NK 1 and NK 2 agonists, namely [Sar 9, Met(O 2) 11]SP and [β-Ala 8] NKA(4-10), upregulated COX-2 protein expression and PG production, whereas senktide (Suc-Asp-Phe-MePhe-Gly-Leu-Met-NH 2), a selective NK 3 agonist, was ineffective in this respect. The NK 1 selective antagonist L703,606 ((cis)-2-(diphenylmethyl)-N-((2- iodophenyl)-methyl)-1-azabicyclo(2.2.2)octan-3-amine) and the NK 2 selective antagonist SR 48,968 ((S)-N-methyl-N-(4-(4-acetylamino-4- phenylpiperidino)-2-(3,4 dichlorophenyl)butyl) benzamide) competitively antagonised SP-induced effects. 6 The study shows HUVEC to possess functional NK 1 and NK 2 receptors, which mediate the ability of SP to induce expression of COX-2 in HUVEC, thus showing a previously-undetected effect of SP on endothelial cells. © 2006 Nature Publishing Group All rights reserved.