ABSTRACT
Diabetic retinopathy is one of the most important causes of blindness. The underlying mechanisms of this disease include inflammatory changes and remodeling processes of the extracellular-matrix (ECM) leading to pericyte and vascular endothelial cell damage that affects the retinal circulation. In turn, this causes hypoxia leading to release of vascular endothelial growth factor (VEGF) to induce the angiogenesis process. Alpha-1 antitrypsin (AAT) is the most important circulating inhibitor of serine proteases (SERPIN). Its targets include elastase, plasmin, thrombin, trypsin, chymotrypsin, proteinase 3 (PR-3) and plasminogen activator (PAI). AAT modulates the effect of protease-activated receptors (PARs) during inflammatory responses. Plasma levels of AAT can increase 4-fold during acute inflammation then is so-called acute phase protein (APPs). Individuals with low serum levels of AAT could develop disease in lung, liver and pancreas. AAT is involved in extracellular matrix remodeling and inflammation, particularly migration and chemotaxis of neutrophils. It can also suppress nitric oxide (NO) by nitric oxide sintase (NOS) inhibition. AAT binds their targets in an irreversible way resulting in product degradation. The aim of this review is to focus on the points of contact between multiple factors involved in diabetic retinopathy and AAT resembling pleiotropic effects that might be beneficial.
Subject(s)
Humans , Animals , Serine Proteinase Inhibitors/therapeutic use , alpha 1-Antitrypsin/therapeutic use , Diabetic Retinopathy/drug therapy , Cell Hypoxia , Serine Proteinase Inhibitors/metabolism , Cell Movement/physiology , Chemotaxis/physiology , alpha 1-Antitrypsin/metabolism , NF-kappa B/metabolism , Tumor Necrosis Factor-alpha/metabolism , Inflammation Mediators/antagonists & inhibitors , Nitric Oxide Synthase/antagonists & inhibitors , Protective Agents/metabolism , Receptors, Proteinase-Activated/metabolism , Diabetic Retinopathy/physiopathology , Free Radicals , Inflammation/metabolism , Anti-Inflammatory Agents/metabolism , Anti-Inflammatory Agents/therapeutic use , Neutrophils/physiologyABSTRACT
El déficit de alfa-1 antitripsina (a-1 AT), también llamado inhibidor de proteasa, es un defecto genético asociado al desarrollo de enfisema pulmonar precoz y menos frecuentemente a cirrosis hepática. Los fenotipos asociados son PiZZ y PiZNulo, caracterizados por un nivel de a-1 AT plasmático menor de 40 mg/dl. La enfermedad pulmonar se presenta habitualmente antes de los 40 años y su progresón es lenta pero puede ser acelerada marcadamente por el hábito tabáquico. La hipótesis del desbalance elastasa-antielastasa postula que la a-1 AT protege al pulmón del daño elastolítico producido por la elastada del neutrófilo. Su déficit lo dejaría altamente vulnerable a una destrucción progresiva que culmina en el enfisema clínico. Como la terapia de aumentar la producción endógena de a-1 AT o disminuir la elastasa no han tenido éxito, su enfoque actual se ha centrado en aumentar la a-1 AT en forma exógena con infusiones iv mensuales, lo que se está probando en un estudio multicéntrico europeo. La terapia genética se encuentra aún en fase experimental