HDL dysfunction in obstructive sleep apnea.
OBJECTIVE
HDL is anti-atherogenic and has antioxidant property. HDL dysfunction has been reported in patients with coronary heart disease and we hypothesize that HDL may also be dysfunctional in obstructive sleep apnea (OSA), a condition associated with increased oxidative stress.


METHODS
128 OSA patients and 82 controls were recruited. HDL dysfunction was determined by evaluating the ability of HDL to inhibit LDL oxidation ex vivo. Plasma HDL was incubated with native LDL in the presence of dichlorofluorescein which fluoresced upon interaction with lipid oxidation products. Plasma levels of oxidized LDL and 8-isoprostane were measured by ELISA and a specific enzyme immunoassay, respectively.


RESULTS
Plasma total 8-isoprostane levels were elevated in OSA subjects (p<0.01). Despite having similar concentrations of plasma lipids and apolipoproteins as controls, OSA subjects had greater degree of HDL dysfunction (p<0.01) and increased oxidized LDL levels (p<0.05). The apnea-hypopnea index was the main determinant of HDL dysfunction in OSA, accounting for 30% of its variance, with oxidized LDL and apolipoprotein AI contributing to 8% and 5% of its variance respectively (p<0.001).


CONCLUSIONS
HDL is dysfunctional in preventing the formation and inactivation of oxidized lipids in OSA subjects and may partly contribute to their increased cardiovascular risk.
Department of Medicine, University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Hong Kong, PR China. kcbtan@hkucc.hku.hk
Kathryn C B
KC
Tan
Wing-Sun
WS
Chow
Jamie C M
JC
Lam
Bing
B
Lam
Wai-Keung
WK
Wong
Sidney
S
Tam
Mary S M
MS
Ip
D000328:Adult; D050197:Atherosclerosis / Q000097:blood / Q000209:etiology; D015415:Biomarkers / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood*; D015237:Dinoprost / Q000031:analogs & derivatives / Q000097:blood; D018450:Disease Progression; D005260:Female; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood* / Q000150:complications; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000097:blood* / Q000150:complications
D015415:Biomarkers; D008076:Cholesterol, HDL; C075750:8-epi-prostaglandin F2alpha; D015237:Dinoprost