Fig. 1

MPO-associated mechanisms in ischemic heart disease. MPO is released by azurophilic granules. MPO is linked to heme by three covalent bonds, and its activity is dependent on Asn421, Asn421 promotes Fe³⁺/Fe²⁺ reduction and contributes to the formation of compound I. One of the main MPO-derived oxidants is HOCl, which affects cell homeostasis by many pathways. In addition, MPO can impair ventricular remodeling and function by affecting MMPs, P38, HDL, LDH, or NO-related signaling pathways. Abridgment MPO myeloperoxidase, Cys cysteine, Asn asparagines, NO nitric oxide, H₂O₂ hydrogen peroxide, LDL low-density lipoprotein, eNOS endothelial nitric oxide synthase, HOCl hypochlorous acidm, MMPs matrix metalloproteinases proteins, HDL high-density lipoprotein