Endothelin-1 and LOX-1 as Markers of Endothelial Dysfunction in Obstructive Sleep Apnea Patients

Introduction: The search of biochemical markers of endothelial dysfunction: lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1)-involved in atherosclerotic plaques formation-and endothelin-1 (ET-1)-potent vasoconstrictor-might help in detecting obstructive sleep apnea (OSA) patients at high risk of cardiovascular diseases. Material and Methods: In 71 OSA patients (apnoea/hypopnoea index, AHI 28.2 +/- 17.9/hour) and in 21 healthy controls the serum levels of LOX-1 and ET-1 were measured. Results: There were increased levels of ET-1 (1.58 +/- 0.65 vs. 1.09 +/- 0.38 pg/mL; p < 0.001) but not of LOX-1 in OSA patients as compared with healthy controls. In the patients' group ET-1 levels negatively correlated with serum LDL levels. LOX-1 levels positively correlated with fasting glucose levels and were higher in the patients with than without diabetes. Neither ET-1 nor LOX-1 correlated with OSA severity. In mild OSA patients, there was a negative correlation between LOX-1 and mean arterial oxygen saturation during sleep. In severe OSA patients, there was a positive correlation between LOX-1 levels and uric acid. Conclusion: There is endothelial dysfunction in OSA patients as indicated by increased serum levels of ET-1 and possibly endothelial dysfunction in diabetic OSA patients as indicated by increased serum levels of LOX-1 and its correlation with fasting glucose levels.

Automated summary

The study found that OSA patients had increased serum levels of ET-1 but not LOX-1. ET-1 negatively correlated with LDL levels, while LOX-1 positively correlated with fasting glucose levels and was higher in diabetic patients. In mild OSA patients, LOX-1 was negatively correlated with mean arterial oxygen saturation during sleep, while in severe OSA patients, LOX-1 levels were positively correlated with uric acid levels.