title: The effect of acute intermittent hypercapnic hypoxia treatment on IL-6, TNF-alpha, and CRP levels in piglets.
abstract: OBJECTIVE
  Obstructive sleep apnea (OSA) is characterized by repeated episodes of upper-airway obstruction during sleep leading to significant hypercapnic hypoxic conditions. These conditions are associated with increased levels of proinflammatory cytokines (including interleukin [IL]-6, tumor necrosis factor [TNF]-alpha, and C-reactive protein [CRP]) and subsequent increased cardiovascular risk. It is unclear whether hypercapnic hypoxia itself causes inflammatory perturbations.
  
  
  METHODS
  We evaluated circulating IL-6, TNF- a and CRP in a piglet model of infant OSA, following exposure to acute intermittent hypercapnic hypoxia (IHH). Study groups comprised of treatment (n = 8) and control (n = 8) groups. Treatment was two 90-minute sessions of IHH with arterial blood sampled before and after each IHH session.
  
  
  RESULTS
  IL-6, TNF-alpha and CRP levels were measured before and after IHH treatment sessions. Results showed an increase in IL-6 following the first session of IHH that was neither sustained, nor repeated, during a subsequent exposure. Using mixed-modelling, TNF-alpha changed between time points and groups. There were no changes in CRP over the duration of the study.
  
  
  CONCLUSIONS
  These results suggest that acute hypoxia causes a transient increase in IL-6 levels and has implications for the pathogenesis of increased cardiovascular disease in OSA, especially in childhood.
authors.affiliation: The Children Hospital at Westmead, Sydney, NSW Australia.
authors.forename: Charmaine S
authors.initials: CS
authors.lastname: Tam
authors.forename: Melanie
authors.initials: M
authors.lastname: Wong
authors.forename: Kimberley
authors.initials: K
authors.lastname: Tam
authors.forename: Leyla
authors.initials: L
authors.lastname: Aouad
authors.forename: Karen A
authors.initials: KA
authors.lastname: Waters
mesh_terms: D000208:Acute Disease; D000818:Animals; D002097:C-Reactive Protein / Q000276:immunology* / Q000378:metabolism; D006935:Hypercapnia / Q000276:immunology / Q000378:metabolism / Q000628:therapy; D000860:Hypoxia / Q000276:immunology / Q000378:metabolism / Q000628:therapy; D015850:Interleukin-6 / Q000097:blood / Q000276:immunology*; D008297:Male; D013552:Swine; D014409:Tumor Necrosis Factor-alpha / Q000097:blood / Q000276:immunology*
chemical_list: D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein