title: Macrophage migratory inhibitory factor (MIF) may be a key factor in inflammation in obstructive sleep apnea.
abstract: OBJECTIVE
  This study investigated the 24-hour variation of macrophage migratory inhibitory factor (MIF), a cytokine which induces insensitivity to the anti-inflammatory effects of glucocorticoids, in patients with untreated obstructive sleep apnea (OSA) as compared to healthy adults with no OSA.
  
  
  METHODS
  Fifty-three men and women with OSA (mean apnea/hypopnea index [AHI] = 39.5) and 24 healthy adults (Non-OSA, AHI = 5.1).
  
  
  METHODS
  Over a 24-h period, blood was collected every 2 h for MIF and cortisol determination. The following night, sleep was monitored with polysomnography.
  
  
  RESULTS
  MIF showed a strong 24-h variation, with a peak at 04:00 and a nadir at 22:00. Patients with OSA showed 25% higher MIF levels (area under the curve) over 24 h than healthy controls. Furthermore, MIF levels were significantly associated with AHI and total arousal index (ArI), even after adjusting for BMI. Cortisol showed the expected 24-h variation (peaking at 06:00), but no cortisol differences were observed between OSA and Non-OSA groups.
  
  
  CONCLUSIONS
  MIF is elevated in patients with OSA and is related to OSA severity, while there was no difference in cortisol levels. MIF is a pro-inflammatory cytokine which additionally inhibits the anti-inflammatory effects of glucocorticoids. Thus, elevated MIF levels in OSA may contribute to elevated inflammation.
authors.affiliation: Department of Psychiatry, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA. kmedwards@ucsd.edu
authors.forename: Kate M
authors.initials: KM
authors.lastname: Edwards
authors.forename: Lianne M
authors.initials: LM
authors.lastname: Tomfohr
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Mills
authors.forename: Jos A
authors.initials: JA
authors.lastname: Bosch
authors.forename: Sonia
authors.initials: S
authors.lastname: Ancoli-Israel
authors.forename: Jose S
authors.initials: JS
authors.lastname: Loredo
authors.forename: Joel
authors.initials: J
authors.lastname: Dimsdale
mesh_terms: D000704:Analysis of Variance; D019540:Area Under Curve; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007249:Inflammation / Q000097:blood* / Q000150:complications; D008263:Macrophage Migration-Inhibitory Factors / Q000097:blood*; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000097:blood* / Q000150:complications
chemical_list: D008263:Macrophage Migration-Inhibitory Factors; D006854:Hydrocortisone