Exogenous Nitric Oxide Inhibits VCAM-1 Expression in Human Peritoneal Mesothelial Cells

Abstract

Leukocyte adhesion to mesothelium is an important step during peritonitis, which is mediated by adhesion molecules including vascular cell adhesion molecule-1 (VCAM-1). We investigated the effect of exogenous nitric oxide (NO) on VCAM-1 expression in cultured human peritoneal mesothelial cells and its signal transduction pathway. Mesothelial cells were exposed to tumor necrosis factor-α (TNF-α) in the presence or absence of NO donors, 3-morpholino-sydnonimine (SIN-1) and nitroprusside (NP). VCAM-1 mRNA and protein expression were measured by Northern blot analysis and flow cytometry. Nuclear factor-ĸB (NF-ĸB) binding activity was determined by electrophoretic mobility shift assay. Both SIN-1 and NP inhibited the TNF-α induced VCAM-1 mRNA expression in a dose dependent manner (0.25–2 mM). SIN-1 also suppressed the cell surface expression of VCAM-1 molecule. Furthermore, SIN-1 and NP inhibited the VCAM-1 mRNA expression induced by interleukin-1β or lipopolysaccharide as well. NF-ĸB inhibitor, PDTC dose dependently inhibited the TNF-α induced VCAM-1 mRNA expression. SIN-1 inhibited the TNF-α- induced NF-ĸB binding activity. Analogue of cGMP (8-bromo-cGMP) had no significant effect on TNF-α-induced VCAM-1 mRNA expression and guanylate cyclase inhibitor (ODQ) also had no significant influence on the inhibitory effect of SIN-1. These results suggest that exogenous NO inhibits VCAM-1 expression via suppression of NF-ĸB through a cGMP-independent pathway.