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Original Research: Sleep Disorders |

Endothelial Dysfunction in Children With Obstructive Sleep Apnea Is Associated With Epigenetic Changes in the eNOS GeneDNA Methylation amp Endothelial Dysfunction in Apnea

Leila Kheirandish-Gozal, MD; Abdelnaby Khalyfa, PhD; David Gozal, MD, FCCP; Rakesh Bhattacharjee, MD; Yang Wang, MD, PhD
Author and Funding Information

From the Section of Sleep Medicine, Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, IL.

Correspondence to: Yang Wang, MD, PhD, 900 E 57th St, KCBD 4100, Chicago, IL 60637; e-mail: ywang@peds.bsd.uchicago.edu


Funding/Support: Drs Kheirandish-Gozal and Gozal are supported by National Institutes of Health (NIH) [Grant K12 HL-090003 to Dr Kheirandish-Gozal and Grant HL-65270 to Dr Gozal].

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2013;143(4):971-977. doi:10.1378/chest.12-2026
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Background:  Obstructive sleep apnea (OSA) is a highly prevalent disorder that has been associated with an increased risk for cardiovascular morbidity, even in children. However, not all children with OSA manifest alterations in endothelial postocclusive hyperemia, an endothelial nitric oxide synthase (eNOS)-dependent response. Since expression of the eNOS gene is regulated by epigenetic mechanisms and OSA may cause epigenetic modifications such as DNA hypermethylation, we hypothesized that epigenetic modifications in the eNOS gene may underlie the differential vascular phenotypes in pediatric OSA.

Methods:  Age-, sex-, ethnicity-, and BMI-matched prepubertal children with polysomnographically confirmed OSA and either normal (OSAn) or abnormal (OSAab) postocclusive hyperemic responses, assessed as the time to attain peak reperfusion flow (Tmax) by laser Doppler flowmetry, were recruited. Blood genomic DNA was assessed for epigenetic modifications in the eNOS gene using pyrosequencing. Children with no evidence of OSA or endothelial dysfunction served as a control group.

Results:  The study comprised 36 children with OSA (11 with OSAab and 25 with OSAn) and 35 children in the control group. Overall, the mean age was 7.5 ± 2.4 years, 65% were boys, and 30% were obese; mean apnea-hypopnea index was 18 ± 8.6/h of sleep for the children with OSA. Tmax was 66.7 ± 8.8 s in the OSAab group and 30.1 ± 8.3 s in the OSAn group (P < .001). Pyrosequencing of the proximal promoter region of the eNOS gene revealed no significant differences in six of the seven CpG sites. However, a CpG site located at position -171 (relative to transcription start site), approximating important transcriptional elements, displayed significantly higher methylation levels in the OSAab group as compared with the OSAn or control groups (81.5% ± 3.5%, 74.8% ± 1.4%, and 74.5% ± 1.7%, respectively; P < .001). eNOS mRNA expression levels were assessed in a separate group of children and were significantly reduced in the OSAab group in comparison with the OSAn group.

Conclusions:  The presence of abnormal eNOS-dependent vascular responses in children with OSA is associated with epigenetic modifications in the eNOS gene.

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