Obstructive sleep apnea (OSA) is a chronic condition that is characterized by recurrent pauses in breathing during sleep causing intermittent hypoxia. The main factor responsible for oxygen metabolism homeostasis is hypoxia-inducible factor 1 (HIF-1), comprised of 2 subunits: α (oxygen sensitive) and β. The aim of the study was to investigate the HIF-1 α serum protein level and mRNA HIF-1 α expression in OSA patients and healthy control group, determine their evening-morning variation and association with polysomnography (PSG) parameters.
Eighty-four individuals were enrolled in the study. All patients underwent PSG examination and based on the results were divided into two groups: OSA group (n=60) and control group (n=24). Peripheral blood was collected in the evening before and in the morning after the PSG. HIF-1 α expression was evaluated on protein in blood serum and mRNA level in peripheral blood leucocytes.
HIF-1 α serum protein concentration was higher in OSA patients compared to control group, in both the evening (1490.1 vs. 727.0 pg/ml; p<0.001), and the morning (1368.9 vs. 702.1 pg/ml; p<0.001) samples. There was no difference between evening and morning HIF-1 α serum protein level in either group. No differences were observed in HIF-1 α mRNA expression between the OSA and control group. Additionally, evening and morning HIF-1 α serum protein level correlated with number of desaturations during sleep (r=0.384, p<0.001 and r=0.433, p<0.001, respectively).
Observed differences in HIF-1 α serum protein level between the OSA and the control groups without difference between evening and morning measurements suggest chronic increase in this protein concentration by intermittent nocturnal hypoxia in OSA.
© 2020 American Academy of Sleep Medicine.