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Physiological role of α1AT α1AT is an acute-phase glycoprotein that is mostly synthesized by hepatocytes and to some extent by other cells like macrophages, lung epithelium, and monocytes. It reaches the lungs by diffusion during systemic circulation. It provides more than 90% of the defence against the elastolytic activity in the lower respiratory tract posed by neutrophil-elastase (NE). Human α1AT is a hydrophilic and tissue diffusible, medium-sized (6.7×3.2 nm) circulating glycoprotein. It has a blood half-life of 4-5 days. The human body is capable of producing approximately 34mg kg-1 day-1 of α1AT, resulting in a high plasma concentration of 1-2 gL-1. During acute-phase response, its levels increase up to fourfold. From circulation, …show more content…

[52-54]. Pathologically, lungs of the emphysema patients show the destruction of alveolar-wall, diffuse-inflammation of respiratory-tract and degradation of the lung parenchyma. Investigations point that chronic inflammation and increased oxidative stress contribute to impaired lung maintenance and repair in emphysema. The inflammation triggered emphysema has revealed activation of innate and acquired immune responses. The accumulation of inflammatory effectors of the immune response contributes to lung injury in COPD patients. The recruitment of inflammatory cells to the lungs triggers the release of inflammatory cytokines and proteases. Together, they directly contribute to parenchymal tissue destruction and its remodelling [55]. Ordinarily, all the proteases released during the course of inflammation in the lungs are inhibited by antiproteases released either locally by the lung epithelium or present in the circulation. The chief inhibitors of serine proteases are α1AT in lung parenchyma and airway-epithelium–derived secretory leukoprotease inhibitor. At least three tissue inhibitors of matrix metalloproteinases (called TIMP-1, TIMP-2, and TIMP-3) counteract matrix metalloproteinases. Cigarette smoking may induce increased release of proteases that are counteracted by antiproteases to prevent lung parenchymal

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