title: The chitinase-like protein YKL-40 is not a useful biomarker for severe persistent asthma in children.
abstract: BACKGROUND
  The chitinase-like protein YKL-40 is thought to play a role in inflammation and tissue remodeling. In adults with severe asthma, YKL-40 is expressed in the airway and YKL-40 levels are elevated in the serum.
  
  
  OBJECTIVE
  To compare YKL-40 levels in children with severe persistent asthma with those in adults with severe persistent asthma and to determine whether YKL-40 levels correlate with increasing asthma severity in childhood asthma.
  
  
  METHODS
  In this prospective, cross-sectional study, 23 adults and 19 children with severe persistent asthma, 23 children with moderate persistent asthma, and 19 children with mild persistent asthma were enrolled. The following data were collected on each patient: spirometry, exhaled nitric oxide, percutaneous skin testing results to aeroallergens, peripheral eosinophils, serum IgE levels, and serum YKL-40 levels.
  
  
  RESULTS
  Compared with adults, children with severe persistent asthma had significantly lower YKL-40 levels, higher values for forced vital capacity and forced expiration volume in 1 second, higher serum IgE levels, and higher exhaled nitric oxide levels. YKL-40 levels did not correlate with increasing asthma severity in the pediatric cohort.
  
  
  CONCLUSIONS
  Severe persistent asthma in childhood is not associated with elevated YKL-40 levels, unlike in adults with severe persistent asthma. YKL-40 is not a useful biomarker for asthma severity in childhood asthma.
authors: Division of Pediatric Allergy and Clinical Immunology, Department of Pediatrics, National Jewish Health, Denver, Colorado.
authors: Carah B
authors: CB
authors: Santos
authors: Division of Pediatric Allergy and Clinical Immunology, Department of Pediatrics, National Jewish Health, Denver, Colorado.
authors: Joshua
authors: J
authors: Davidson
authors: Division of Pediatric Allergy and Clinical Immunology, Department of Pediatrics, National Jewish Health, Denver, Colorado.
authors: Ronina A
authors: RA
authors: Covar
authors: Division of Pediatric Allergy and Clinical Immunology, Department of Pediatrics, National Jewish Health, Denver, Colorado. Electronic address: SpahnJ@NJHealth.org.
authors: Joseph D
authors: JD
authors: Spahn
mesh_terms: D054392:Adipokines / Q000378:metabolism*; D000293:Adolescent; D001249:Asthma / Q000175:diagnosis* / Q000378:metabolism*; D015415:Biomarkers; D002648:Child; D002675:Child, Preschool; D000071451:Chitinase-3-Like Protein 1; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D037102:Lectins / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012720:Severity of Illness Index
chemical_list: D054392:Adipokines; D015415:Biomarkers; C084533:CHI3L1 protein, human; D000071451:Chitinase-3-Like Protein 1; D037102:Lectins