The Plasminogen System and TGF-b in OSAS subjects: Effects of CPAP treatment

Introduction 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 OSAS subjects. These alterations in coagulation seem to involve the Plasminogen Activation (PA) system. We evaluated the imbalances of the PA system related to OSAS, and we assessed the effects of continuous positive airway pressure (CPAP) on the PA system. Methods Thirty-nine subjects were submitted to home based cardio-respiratory sleep study, and 14 healthy subjects (AHI<5) were used as the controls. Serum levels of urokinase-type PA (uPA), tissue-type PA (tPA), PA inhibitor-1 (PAI-1) and active transforming growth factor-β (TGF-β) were measured. These molecules were reassessed in only 17 of the patients after one month of CPAP. Results PAI-1 and tPA were significantly higher in the OSAS subjects compared to the controls, while TGF-b and uPA levels were lower. PAI-1 showed a significant positive correlation with the apnea hypopnea index (AHI), percentage of time spent at O2 saturation below 90% (T < 90%), and oxygen desaturation index (ODI), while TGF-b was inversely related to all three of these parameters. After the CPAP therapy, PAI-1 significantly decreased, while TGF-b showed a significant increase, even though the values did not reach those of the controls. Urokinase-PA 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.