Copper induces - and copper chelation by tetrathiomolybdate inhibits - endothelial activation in vitro

Endothelial activation with increased expression of cellular adhesion molecules and chemokines critically contributes to vascular inflammation and atherogenesis. Redox-active transition metal ions play an important role in vascular oxidative stress and inflammation. Therefore, the goal of the present study was to investigate the role of copper in endothelial activation and the potential anti-inflammatory effects of copper chelation by tetrathiomolybdate (TTM) in human aortic endothelial cells (HAECs). Incubating HAECs with cupric sulfate dose-and time-dependently increased mRNA and protein expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and monocyte chemotactic protein-1 (MCP-1). Copper also activated the redox-sensitive transcription factors, nuclear factor kappa B (NF-kappa B) and activator protein-1 (AP-1), which was inhibited by pretreatment of the cells with TTM. Furthermore, TTM dose-dependently inhibited tumor necrosis factor alpha (TNF alpha)-induced activation of NF-kappa B and AP-1, as well as mRNA and protein expression of VCAM-1, ICAM-1, and MCP-1, which was abolished by preincubating the cells with 5 mu M TTM and 15 mu M cupric sulfate. The inhibitory effect of TTM on TNF alpha-induced NF-kappa B activation was associated with decreased phosphorylation and degradation of I kappa B alpha. These data suggest that intracellular copper causes activation of redox-sensitive transcription factors and upregulation of inflammatory mediators in endothelial cells. Copper chelation by TTM may attenuate TNF alpha-induced endothelial activation and, hence, inhibit vascular inflammation and atherosclerosis.