Effects of antioxidants and NO on TNF- α-induced adhesion molecule expression in human pulmonary microvascular endothelial cells

Abstract

Pro-inflammatory cytokines initiate the vascular inflammatory response via upregulation of adhesion molecules on the endothelium. Recent observations suggest that reactive oxygen intermediates may play a pivotal role in TNF-alpha signaling and upregulate gene expression. We therefore evaluated the effects of pyrrolidine dithiocarbamate (PDTC; 0.1 mM) and spermine NONOate (Sper-NO; 1 mM) on adhesion molecule expression and nuclear factor kappa B (NF-kappaB) activation induced by TNF-alpha (10 ng/ml) in cultured human pulmonary microvascular endothelial cells (PMVEC). Treatment of cells with TNF-alpha for 4 h significantly induced the surface expression of E-selectin and ICAM-1. Treatment with TNF-alpha for 8 h significantly induced the surface expression of E-selectin, ICAM-1 and VCAM-1. The upregulation of these adhesion molecules was suppressed significantly by pretreatment with PDTC or Sper-NO for 1 h. 8-Bromo-cyclic GMP (1 mM) had no such effect, suggesting that the NO donor's effect was non-cGMP-dependent. The mRNA expression of E-selectin, ICAM-1 and VCAM-1, and activation of NF-kappaB induced by TNF-alpha for 2 h were decreased significantly by the above two pretreatments. N-acetylcysteine (10 mM) and S-nitroso-N-acetylpenicillamine (1 mM) had little inhibitory effects on the cell surface and mRNA expression of these adhesion molecules stimulated by TNF-alpha. Treatment with TNF-alpha for 4 h enhanced HL-60 leukocyte adhesion to human PMVEC, the effect of which was inhibited significantly by pretreatment with PDTC or Sper-NO. These findings indicate that both cell surface and mRNA expression of adhesion molecules in human PMVEC induced by TNF-alpha are inhibited significantly by pretreatment with PDTC or Sper-NO, possibly in part through blocking the activation of NF-kappaB. Although our in vitro results cannot be directly extrapolated to the in vivo situation, they suggest a potential therapeutic approach for intervention in cytokine-mediated inflammatory processes in the human lung.