T regulatory lymphocytes and endothelial function in pediatric obstructive sleep apnea.
BACKGROUND
Obstructive sleep apnea (OSA) is a low-grade inflammatory disease affecting the cardiovascular and metabolic systems. Increasing OSA severity reduces T-regulatory lymphocytes (Tregs) in OSA children. Since Tregs modulate endothelial activation, and attenuate insulin resistance, we hypothesized that Tregs are associated with endothelial and metabolic dysfunction in pediatric OSA.


METHODS
50 consecutively recruited children (ages 4.8-12 years) underwent overnight polysomnography and fasting homeostatic model (HOMA) of insulin resistance was assessed. Percentage of Tregs using flow cytometry, and endothelial function, expressed as the time to peak occlusive hyperemia (Tmax), were examined. In a subgroup of children (n = 21), in vitro Treg suppression tests were performed.


RESULTS
Circulating Tregs were not significantly associated with either BMI z score or HOMA. However, a significant inverse correlation between percentage of Tregs and Tmax emerged (p<0.0001, r = -0.56). A significant negative correlation between Tregs suppression and the sleep pressure score (SPS), a surrogate measure of sleep fragmentation emerged (p = 0.02, r = -0.51) emerged, but was not present with AHI.


CONCLUSIONS
Endothelial function, but not insulin resistance, in OSA children is strongly associated with circulating Tregs and their suppressive function, and appears to correlate with sleep fragmentation. Thus, alterations in T cell lymphocytes may contribute to cardiovascular morbidity in pediatric OSA.
Section of Pediatric Sleep Medicine, Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, Illinois, USA.
Hui-Leng
HL
Tan
David
D
Gozal
Arash
A
Samiei
Rakesh
R
Bhattacharjee
Yang
Y
Wang
Helena Molero
HM
Ramirez
Hari P R
HP
Bandla
Richa
R
Kulkarni
Leila
L
Kheirandish-Gozal
D015992:Body Mass Index; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004730:Endothelium, Vascular / Q000378:metabolism*; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D018655:Lymphocyte Count; D008297:Male; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000276:immunology* / Q000378:metabolism* / Q000503:physiopathology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*