title: Elevated levels of neopterin in sleep-disordered breathing.
abstract: BACKGROUND
  Sleep-disordered breathing (SDB) is increasingly being recognized as an independent risk factor for hypertension and cardiovascular disease. Recent evidence suggests that the maladaptive physiologic response to SDB, particularly cardiovascular effects, may result in part from systemic inflammation. Although abnormal cytokine levels have been documented in SDB, data on whether SDB is associated with cellular activation are limited. Thus, this investigation sought to determine whether neopterin, a marker released by activated macrophages, is increased in SDB.
  
  
  RESULTS
  Fifty-five men, free of medical comorbidity, undergoing polysomnography had fasting serum tested for neopterin levels. Multivariable regression methods were used to quantify the association between neopterin and quartiles of the apnea hypopnea index (AHI) while accounting for body mass index, waist circumference, and percentage of body fat. Quartiles of AHI (I: < 3.83 events per hour; II: 3.83 to 11.98 events per hour; III: 11.99 to 36.82 events per hour; IV > 36.82 events per hour) indicated a range from no SDB through severe SDB. Compared to the subjects in the first AHI quartile, serum neopterin levels were higher by 3.0%, 10.9%, and 26.5% in the second, third, and fourth AHI quartiles, respectively (p < 0.001for linear trend). Neopterin levels also were higher in those with greater degree of sleep-related hypoxemia, more stage 1 sleep, and less stage 2 sleep.
  
  
  CONCLUSIONS
  The results of this study indicate that severity of SDB independently associates with serum levels of neopterin, a marker for macrophage activation that may play an important role in the pathogenesis of SDB-related cardiovascular disease.
authors.affiliation: Johns Hopkins University, Division of Pulmonary and Critical Care Medicine, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA. npunjabi@jhmi.edu
authors.forename: Naresh M
authors.initials: NM
authors.lastname: Punjabi
authors.forename: Brock A
authors.initials: BA
authors.lastname: Beamer
authors.forename: Alka
authors.initials: A
authors.lastname: Jain
authors.forename: Monique E
authors.initials: ME
authors.lastname: Spencer
authors.forename: Neal
authors.initials: N
authors.lastname: Fedarko
mesh_terms: D000328:Adult; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000209:etiology; D003430:Cross-Sectional Studies; D006801:Humans; D008262:Macrophage Activation; D008297:Male; D008875:Middle Aged; D019798:Neopterin / Q000097:blood*; D010108:Oxyhemoglobins / Q000032:analysis; D011379:Prognosis; D012720:Severity of Illness Index; D012891:Sleep Apnea Syndromes / Q000097:blood* / Q000503:physiopathology
chemical_list: D010108:Oxyhemoglobins; D019798:Neopterin