Increased levels and activity of matrix metalloproteinase-9 in obstructive sleep apnea syndrome

Matrix metalloproteinases (MMPs) are involved in the pathogenesis of cardiovascular diseases. We examined serum levels of MMP-9 and its inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), activity of MMP-9, and the effect of nasal continuous positive airway pressure (nCPAP) in patients with obstructive sleep apnea syndrome (OSAS). After polysomnography, venous blood was collected at 5:00 A.M. from 44 patients with OSAS and 18 control subjects who were obese, and serum levels of MMP-9, TIMP-1, and enzymatic activity of MMP-9 were measured. In addition, the effects of 1 month of treatment with nCPAP were studied in patients with moderate to severe OSAS. Although serum levels of MMP-9 (p < 0.03) and MMP-9 activity (p < 0.01) were higher in patients with OSAS than in control subjects who were obese, TIMP-1 levels did not differ significantly. In patients with OSAS, the severity of OSAS was the primary factor influencing levels (p < 0.01) and activity (p < 0.01) of MMP-9. nCPAP significantly decreased serum levels (p < 0.01) and activity (p < 0.001) of MMP-9 but did not affect TIMP-1 levels. Therefore, OSAS may increase risks of cardiovascular morbidity, and nCPAP might be useful for decreasing these risks.