title: Plasma interleukin 6 levels are elevated in polycystic ovary syndrome independently of obesity or sleep apnea.
abstract: Premenopausal women with polycystic ovary syndrome (PCOS) are at a much higher risk for excessive daytime sleepiness, fatigue, and insulin resistance than control women. Elevated levels of interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) are presumably part of the pathogenesis of these clinical manifestations. Forty-two obese women with PCOS, 17 body mass index-comparable obese controls, and 15 normal-weight controls free from apnea participated in the study that included one 8-hour nighttime polysomnography, single morning cytokine plasma concentrations, and insulin resistance indices. Women with PCOS exhibited higher plasma concentrations of IL-6 than obese controls, who had intermediate values, or normal-weight controls, who had the lowest values (4.75 +/- 0.5 vs 3.65 +/- 0.4 vs 1.84 +/- 0.3 pg/mL, P < .01). Tumor necrosis factor alpha values were higher in PCOS and obese controls compared with normal-weight controls, but the difference was not statistically significant (4.05 +/- 0.3 vs 3.79 +/- 0.2 vs 3.14 +/- 0.2 pg/mL, P = .103). Based on backward regression analysis, IL-6 levels had a stronger association with the PCOS group than with the obese group, and the sleep or hypoxia variables did not make a significant contribution to either IL-6 or TNF-alpha. Both IL-6 and TNF-alpha correlated positively with body mass index (P < .01) in obese controls but not in women with PCOS. Furthermore, within the PCOS group, IL-6 and TNF-alpha correlated more strongly with indices of insulin resistance than obesity. We conclude that IL-6 levels are elevated in obese women with PCOS independently of obesity or sleep apnea and may represent a pathophysiologic link to insulin resistance.
authors.affiliation: Sleep Research and Treatment Center, Department of Psychiatry H073, Penn State University College of Medicine, Hershey, PA 17033, USA. axv3@psu.edu
authors.forename: Alexandros N
authors.initials: AN
authors.lastname: Vgontzas
authors.forename: Georgia
authors.initials: G
authors.lastname: Trakada
authors.forename: Edward O
authors.initials: EO
authors.lastname: Bixler
authors.forename: Hung-Mo
authors.initials: HM
authors.lastname: Lin
authors.forename: Slobodanka
authors.initials: S
authors.lastname: Pejovic
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Zoumakis
authors.forename: George P
authors.initials: GP
authors.lastname: Chrousos
authors.forename: Richard S
authors.initials: RS
authors.lastname: Legro
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology; D016207:Cytokines / Q000097:blood; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D015850:Interleukin-6 / Q000097:blood*; D009765:Obesity / Q000097:blood*; D011085:Polycystic Ovary Syndrome / Q000097:blood*; D017286:Polysomnography; D012129:Respiratory Function Tests; D012891:Sleep Apnea Syndromes / Q000097:blood*; D013739:Testosterone / Q000097:blood; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D016207:Cytokines; D007328:Insulin; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D013739:Testosterone