The role of metalloproteinases in the pathogenesis of Obstructive Sleep Apnea Syndrome

Obstructive Sleep Apnea Syndrome (OSAS) is a common sleep-related breathing disorder. Untreated OSAS leads to significant health consequences, disturbed functioning in society, decreased efficiency in a workplace and increased risk of accidents at work and while driving. The main patomechanisms of OSAS development are hypoxia, oxidative stress and inflammatory process. Intermittent hypoxia in OSAS patients is associated with subsequent episodes of reoxygenation with simultaneous increase of reactive oxygen species and reactive nitrogen species that stimulate secretion of extracellular metalloproteinases (MMPs). These compounds belong to a group of endogenous proteolytic enzymes produced by structural cells of extracellular matrix (ECM) and by cells of inflammatory response as well. ECMs are made of collagen proteins and glycoproteins. They form a scaffold for tissues of the soft palate. MMPs break down collagen molecules, which results in flaccidity of tissues, including tissues of the soft palate. The results of scientific studies have shown that expression, secretion, and activeness of MMPs increase during hypoxia. Thus metalloproteinases may be involved in the process of upper airway tissue damage during the intermittent hypoxia in OSAS.