Effect of Nasal CPAP on SIRT1 and Endothelial Function in Obstructive Sleep Apnea Syndrome

Background Sirtuin 1 (SIRT1), a histone/protein deacetylase, has been implicated in aging, metabolism, and stress resistance. SIRT1 regulates endothelial nitric oxide (NO) synthase, restores NO availability, and is involved in different aspects of cardiovascular disease. The aim of this study was to evaluate any abnormalities with regard to SIRT1 protein level in the blood, SIRT1 activity, and impaired endothelial function in patients with obstructive sleep apnea syndrome (OSAS). We also investigated whether or not OSAS patients who received nasal continuous positive airway pressure (CPAP) treatment showed improvements in the levels of SIRT1. Methods Thirty-five patients with moderately severe to severe OSAS who requested nasal CPAP treatment and 20 healthy controls were prospectively enrolled. The SIRT1 protein levels in blood and its activity, and the serum levels of nitric oxide derivative (NO x ) were assessed. All subjects participated in sleep studies, which were repeated 3 months after nasal CPAP treatment in the patients with OSAS. Results In the patients with OSAS, the level of SIRT1 in the blood, its activity, and that of NO x was lower than those of normal subjects before nasal CPAP treatment. After nasal CPAP treatment, the level of SIRT1 in the blood and its activity increased from 0.55 ± 0.32 pg/μg of total protein and 3085.53 ± 1071.57 arbitrary fluorescence units (AFUs)/μg of total protein to 1.13 ± 0.43 pg/μg of total protein and 5344.65 ± 1579.71 AFUs/μg of total protein. The serum levels of NO x in the patients with OSAS increased from 16.36 ± 5.78 to 25.94 ± 5.17 µM. Conclusions Successful treatment for OSAS with nasal CPAP can restore blood levels of the SIRT1 protein and its activity and serum levels of NO x .