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

1 Substance P (SP) is a neuropeptide involved in neurogenic inflammation and an agonist for NK1, NK2, and NK3 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 NK1 and NK2 but not NK3 receptors are present on HUVEC. Selective NK1 and NK2 agonists, namely [Sar(9), Met(O-2)(11)] SP and [beta-Ala(8)] NKA(4 - 10), upregulated COX-2 protein expression and PG production, whereas senktide (Suc - Asp - Phe - MePhe - Gly - Leu - Met - NH2), a selective NK3 agonist, was ineffective in this respect. The NK1 selective antagonist L703,606 ((cis)-2-(diphenylmethyl)-N-((2-iodophenyl)- methyl)-1-azabicyclo( 2.2.2) octan-3-amine) and the NK2 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 NK1 and NK2 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.