Glycated Serum Albumin-Induced Nitric Oxide Production in Vascular Smooth Muscle Cells by Nuclear Factor κB-Dependent Transcriptional Activation of Inducible Nitric Oxide Synthase

Abstract

Glycated proteins, including serum albumin, may be involved in the pathogenesis of diabetic vasculopathy. Recent evidence suggests that expression of inducible nitric oxide synthase (iNOS) in vascular smooth muscle cells (VSMC) may, in part, promote atherosclerosis by increasing local oxidative stress. We therefore investigated whether VSMC exposed to glycated human serum albumin (GHSA) produce nitric oxide (NO) by increasing iNOS expression through transcriptional activation of the iNOS gene and whether this process is dependent on nuclear factor κB (NF-κB) activation. Treatment of VSMC with GHSA causes activation of NF-κB and the iNOS promoter. Induction of NF-κB and the iNOS promoter by GHSA exhibited dose-dependent kinetics at concentrations ranging from 3 to 1000 μg/ml. GHSA alone was a weak inducer of NO production in VSMC as measured by determining nitrite levels, and interferon-γ alone was totally ineffective, whereas the combination of GHSA and interferon-γ was a strong stimulus. This synergy for NO production corresponded to Northern blot analyses of iNOS mRNA expression. Thus, GHSA may promote atherosclerosis in part by activation of NF-κB and upregulation of iNOS, thereby fostering local inflammation and oxidative stress.