Plasma lactoferrin level as a predictor to endothelial dysfunction in patients with obstructive sleep apnea

Abstract

Background Obstructive sleep apnea (OSA) syndrome is associated with cardiovascular complications attributed to endothelial dysfunction. There are contradictory reports on whether lactoferrin is protective or injurious to the blood vessels. Objectives To determine circulating plasma lactoferrin level in OSA patients in relation to endothelial dysfunction and to assess its relation to other criteria of OSA. Patients and methods In a cross-sectional study, 40 OSA patients were recruited after an established diagnosis in the sleep laboratory of the pulmonary medicine department. Doppler flow-mediated dilatation percentage (FMD%) was tested as an indicator of endothelial function. Anthropometric measurements, systolic and diastolic blood pressure, lipid profile, plasma lactoferrin level, fasting, and 2 h postprandial plasma glucose (PPG) were estimated in the patients and the control groups. Moreover, the apnea-hypopnea index, and the mean and nadir nocturnal oxygen saturation of OSA patients were determined. Results OSA patients were found to have significantly higher BMI, waist circumference (WC), neck circumference, fasting plasma glucose (FPG), 2 h PPG, low-density lipoprotein-cholesterol, and lower plasma lactoferrin, FMD%, and high-density lipoprotein (HDL)-cholesterol compared with the control group. There was a significant direct correlation between FMD%, as an indicator of endothelial function, and plasma lactoferrin level as well as HDL-cholesterol, and an inverse correlation between FMD% and BMI, WC, FPG, 2 h PPG, and basal brachial artery diameter. Multiple regression analysis showed that lactoferrin was the only independent predictor for FMD% among OSA patients. However, plasma lactoferrin level was inversely correlated with BMI, WC, FPG, and 2 h PPG, and was directly correlated with HDL-cholesterol and FMD%. Multiple regression analysis selected BMI and FMD% as the independent predictors for lactoferrin level. Conclusion The present study showed that low circulating plasma lactoferrin levels in OSA patients independently predict endothelial dysfunction as assessed by FMD%. High BMI in OSA patients negatively influences plasma lactoferrin levels unrelated to other OSA severity predictors.

Keywords

• endothelial dysfunction, flow-mediated dilatation, lactoferrin, obstructive sleep apnea