The association between enhanced MPO expression and increased levels of free iron is characteristic of many inflammatory disorders including cardiovascular diseases such atherosclerosis, pulmonary diseases such as cystic fibrosis, neurodegenerative diseases such as Alzheimer’s disease as well as arthritis, diabetes, and has been found to be a risk factor for various cancers [28, 29, 31, 70–75]. Here, MPO is linked to arthritic joint disease.