Nitric oxide inhibits intracellular adhesion molecule-1 expression in rat mesangial cells

This study tested whether nitric oxide modulates the expression of intercellular adhesion molecule-1 (ICAM-1) expression in glomerular mesangial cells. In an enzyme-linked immunosorbent assay, interleukin 1 beta (IL-1 beta; 10 ng/mL) increased ICAM-1 molecule expression on cultured rat mesangial cell surface in a time-dependent manner. Addition of the nitric oxide donors 3-morpholino-sydnonimine (SIN-1) or sodium nitroprusside significantly suppressed IL-1 beta-induced ICAM-1 molecule expression in a dose-dependent manner. The inhibitory effect of SIN-1 was abolished in the presence of a nitric oxide scavenger hemoglobin, but not in the presence of superoxide dismutase or pyrrolidine dithiocarbamate. Addition of 8-bromo-cyclic GMP showed no significant effect on IL-1 beta-induced ICAM-1 expression. In Northern blot analysis, the expression of ICAM-1 mRNA was barely detected in unstimulated cells, whereas ICAM-1 gene transcripts were clearly expressed after exposure to IL-1 beta for 3 h, and addition of SIN-1 decreased IL-1 beta-induced ICAM-1 mRNA accumulation. These results suggest that nitric oxide suppresses ICAM-1 expression in IL-1 beta-stimulated mesangial cells, independent of cGMP formation.