myeloperoxidase

MPO (myeloperoxidase) is a peroxidase enzyme secreted by activated leukocytes that plays a pathogenic role in cardiovascular disease, mainly by initiating endothelial dysfunction. Myeloperoxidase (MPO) is an important enzyme, which is one of the components of the antibacterial system in neutrophils and monocytes. MPO participates in the inflammatory response in multiple locations in the body, including the mammary glands. Myeloperoxidase (MPO), a specific polymorphonuclear leukocyte enzyme, has been used previously to quantify the number of neutrophils in tissue. MPO activity was found to be linearly related to the number of neutrophil cells. The MPO system plays an important role in the control of infections and the deletion of malignant cells. Nevertheless, alternations in the MPO system can lead to DNA damage and carcinogenesis. Polymorphisms in the MPO gene have been associated with an increased expression of MPO and a higher risk for the development of cancer. Myeloperoxidase (MPO) is one of the major target antigens of antineutrophil cytoplasmic autoantibodies (ANCA) found in patients with small-vessel vasculitis and Pauci-immune necrotizing glomerulonephritis. Myeloperoxidase-anti-neutrophil cytoplasmic antibody (MPO-ANCA) is an autoantibody that is frequently found in patients with vasculitides.

Myeloperoxidase (MPO) is a hemecontaining enzyme belonging to the XPO subfamily of peroxidases. It is an abundant neutrophil and monocyte glycoprotein that catalyzes the hydrogen peroxidedependent conversion of chloride, bromide, and iodide to multiple reactive species. MPO activity results in protein nitrosylation and the formation of 3-chlorotyrosine and dityrosine crosslinks. Modification of ApoB100, as well as the lipid and cholesterol components of LDL and HDL, promotes the development of atherosclerosis. MPO is also associated with a variety of other diseases, and inhibits vasodilation in inflammation by depleting the levels of NO. Serum albumin functions as a carrier protein during MPO movement to the basolateral side of epithelial cells. MPO is stored in neutrophil azurophilic granules. Upon cellular activation, it is deposited into pathogencontaining phagosomes. While mice lacking MPO are impaired in clearing select microbial infections,MPO deficiency in humans does not necessarily result in heightened susceptibility to infections.