Circulating Survivin Levels in Obstructive Sleep Apnoea

Abstract

INTRODUCTION: Obstructive sleep apnoea (OSA) is characterised by a low-grade systemic and airway inflammation; however, the regulatory mechanisms of inflammation are poorly explored. Survivin (Birc5) is an anti-apoptotic protein which inhibits Type 1 inflammation; however, this molecule has not been investigated in OSA. METHODS: Forty-five patients with OSA and 31 non-OSA control subjects were involved. Venous blood was collected for plasma survivin measurements before and after diagnostic overnight polysomnography. Plasma survivin levels were compared between the two groups and correlated to OSA severity and comorbidities. RESULTS: Plasma survivin levels were lower in OSA in the evening (27.6 +/- 89.9 vs. 108.3 +/- 161.2 pg/ml, p < 0.01) and in the morning (17.4 +/- 48.6 vs. 36.4 +/- 69.2 pg/ml, p = 0.02) compared to the control group. This OSA-related decrease was also present when only the non-obese patients were analysed. Significant indirect relationships were observed between plasma survivin levels and measures of OSA severity such as the apnoea-hypopnoea index (r = - 0.45) or oxygen desaturation index (r = - 0.40, both p < 0.01); however, when adjusting to BMI, these became insignificant (p > 0.05). Low plasma survivin concentrations were associated with high BMI (r = - 0.35), high CRP (r = - 0.31), low HDL cholesterol (r = 0.24) and high triglyceride levels (r = - 0.24, all p < 0.05). CONCLUSION: Plasma survivin levels are reduced in OSA, relate to disease severity, and are associated with high CRP levels. This suggests an impaired immunoregulation in this disorder which needs to be studied in further detail.