Iodide modulates protein damage induced by the inflammation-associated heme enzyme myeloperoxidase.

Iodide ions (I) are an essential dietary mineral, and crucial for mental and physical development, fertility and thyroid function. I is also a high affinity substrate for the heme enzyme myeloperoxidase (MPO), which is involved in bacterial cell killing during the immune response, and also host tissue damage during inflammation. In the presence of HO and Cl, MPO generates the powerful oxidant hypochlorous acid (HOCl), with excessive formation of this species linked to multiple inflammatory diseases.

Chlorination and oxidation of the extracellular matrix protein laminin and basement membrane extracts by hypochlorous acid and myeloperoxidase.

Basement membranes are specialized extracellular matrices that underlie arterial wall endothelial cells, with laminin being a key structural and biologically-active component. Hypochlorous acid (HOCl), a potent oxidizing and chlorinating agent, is formed in vivo at sites of inflammation via the enzymatic action of myeloperoxidase (MPO), released by activated leukocytes. Considerable data supports a role for MPO-derived oxidants in cardiovascular disease and particularly atherosclerosis.