The Plasminogen System and Transforming Growth Factor-β in Subjects With Obstructive Sleep Apnea Syndrome: Effects of CPAP Treatment.

BACKGROUND Obstructive sleep apnea syndrome (OSAS) has emerged as a risk factor for cardiovascular disease. A prothrombotic state may affect coagulation and participate in the atherosclerotic process in subjects with OSAS. These alterations in coagulation seem to involve the plasminogen activation system. We evaluated the imbalances of the plasminogen activation system related to OSAS, and we assessed the effects of CPAP on the plasminogen activation system. METHODS Thirty-nine subjects were submitted to a home-based cardiorespiratory sleep study, and 14 healthy subjects (apnea-hypopnea index < 5) were used as controls. Serum levels of urokinase-type plasminogen activator (uPA), tissue-type plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), and active transforming growth factor-β (TGF-β) were measured. These molecules were reassessed in only 17 of the subjects after 1 month of CPAP. RESULTS PAI-1 and tPA were significantly higher in the subjects with OSAS compared with the controls, whereas TGF-β and uPA levels were lower. PAI-1 showed a significant positive correlation with the apnea-hypopnea index, percentage of time spent at O2 saturation < 90%, and oxygen desaturation index, whereas TGF-β was inversely related to all 3 of these parameters. After the CPAP therapy, PAI-1 significantly decreased, whereas TGF-β showed a significant increase, although the values did not reach those of the controls. uPA and tPA did not show significant differences after the treatment. CONCLUSIONS Our results suggest an imbalance of fibrinolysis related to OSAS and an improvement of the prothrombotic state after the CPAP treatment.