Combined cupric- and cuprous-binding peptides are effective in preventing IL-8 release from endothelial cells and redox reactions

Abstract

Copper mobilization and subsequent redox reactions have been implicated in the pathogenesis of numerous inflammation-based diseases. Reduction of the cupric ion (Cu 2+) to the cuprous ion (Cu +) is necessary for the production of copper-induced reactive oxygen species (ROS). Peptides, designed to bind both Cu 2+ and Cu + and have the ability to prevent copper redox reactions, were studied. The peptides DAHGMTCA NC and DAHKGMTCA NC were effective at preventing the formation of thiobarbituric acid-reactive species (TBARS) in a copper/ascorbate solution at a 1:1 peptide/Cu ratio. This was observed in the reducing potential of the copper/ascorbate solutions containing these peptides at a 1:1 ratio based on oxidation–reduction potential (ORP) measurements. The peptide DAHGMTCA RC was effective at a 2:1 ratio, but not at a 1:1 ratio in which an increase in the oxidation potential was observed. This suggests that a positively charged amino acid such as arginine (R) in the Cu +-binding motif interferes with metal chelation. All peptides tested were effective at preventing IL-8 release from phorbol 12-myristate 13-acetate (PMA)/copper-stimulated human umbilical vein endothelial cells (HUVEC). The use of Cu +/Cu 2+-binding peptides might be beneficial in the treatment of ROS-related diseases associated with copper.