Description
α1-antichymotrypsin (α1-ACT), also called SERPINA3, is an acute phase serum glycoprotein that belongs to a member of the serine protease inhibitor family. α1-ACT inhibits the activity of certain leukocyte-derived proteases, such as cathepsin G that is found in neutrophils, chymases found in mast cells and Prostate-specific Antigen (PSA) by cleaving them into a different shape or conformation. This activity protects some tissues, such as the lower respiratory tract, from damage caused by proteolytic enzymes.
Although α1-ACT is predominantly produced in the liver, it is also synthesized in the brain, mainly by astrocytes. Elevated levels of α1-ACT are found in serum, brain and cerebrospinal fluid of Alzheimer's disease patients, and high levels of α1-ACT in plasma is associated with cognitive decline in elderly subjects.
Earlier studies have shown that α1-ACT enhances amyloid beta fibrillization and accelerated plaque formation in Amyloid precursor protein transgenic mice. Later studies have shown that purified α1-ACT induces tau hyperphosphorylation and degeneration in neurons.
In addition, α1-ACT elevation in tear fluid emerges as a promising biomarker for the diagnosis of multiple sclerosis