A2M and Alzheimer disease: As an example, it may help to explain the paradoxical involvement of many seemingly odd proteins in AD pathogenesis, such as C-reactive protein [149], plasmin/plasminogen system [150, 151], complement proteins [152, 153], alpha-2-macroglobulin [152], ferritin [154, 155], fibrinogen [156], ceruloplasmin [157], haptoglobin [158], hepcidin [159], mannose-binding lectin [160], and serpins (e.g., SERPINF2/alpha-2-antiplasmin, neuroserpin and alpha(1)-antichymotrypsin) [151, 161].