Nitric Oxide Inhibits VCAM-1 Expression in Human Peritoneal Mesothelial Cells: Possible Role of Cyclic GMP and NF-kappa B

Kim, Ji Hoon; Yang, Won Seok; Kim, Soon Bae; Park, Su Kil; Lee, Sang Koo; Park, Jung Sik

Abstract

Leukocyte adhesion to mesothelium is an important step during peritonitis, which may be mediated by adhesion molecules including vascular cell adhesion molecule-1(VCAM-1). Nitric oxide(NO) is known to be an endogenous inhibitor of leukocyte adhesion. We investigated the effect of NO on VCAM-1 expression in cultured human peritoneal mesothelial cells and the possible role of cGMP and NF-kappa B. Cells were exposed to tumor necrosis factor-alpha(TNF-alpha) for the indicated periods in the presence or absence of NO donors, 3-morpholino-sydnonimine (SIN-1) or nitroprusside(NP). The expression of VCAM-1 mRNA and cell surface VCAM-1 molecule was measured by Northern blot analysis and flow cytometry. To detect NF-kappa B binding activity, electrophoretic mobility shift assay(EMSA) was performed. To determine the role of guanylate cyclase or cGMP, inhibitor of guanylate cyclase, 1H-[1, 2, 4] oxadiazolo [4, 3-a] quinoxalin-1-one(ODQ) or analogue of cGMP, 8-bromo-cGMP was used. Both SIN-1 and NP inhibited the TNF-alpha-induced VCAM-1 mRNA expression in a dose dependent manner. SIN-1 also inhibited the expression of cell surface VCAM-1 molecule. Furthermore, SIN-1 and NP inhibited the expression of VCAM-1 mRNA induced by interleukin-1(IL-1beta) or lipopolysaccharide(LPS) as well. By EMSA, SIN-1 inhibited the TNF-alpha-induced NF-kappa B activity. The 8-bromo-cGMP had no significant effect on TNF-alpha-induced VCAM-1 mRNA expression and ODQ also had no significant influence on the inhibitory effect of SIN-1. In conclusion, NO may play an important role in mediating the inflammatory process during peritonitis by down-regulating the mesothelial VCAM-1 expression via suppression of NF-kappa B activity through cGMP- independent pathway.