title: Cathelicidin (LL-37) and human β2-defensin levels of children with post-infectious bronchiolitis obliterans.
abstract: BACKGROUND
  The antimicrobial peptides (AMPs) human β-defensins and cathelicidin (LL-37) are key factors in innate and adaptive immune responses of the respiratory tract and play an important role in many respiratory diseases. No data are available in the literature about the levels of these AMPs in paediatric patients with post-infectious bronchiolitis obliterans (BO). This study aimed to determine human β-defensin 2 (hBD2) and LL-37 levels and compare between post-infectious BO patients and the control group.
  
  
  METHODS
  The patients diagnosed with post-infectious BO between September 2012 and 2013 and age- and-gender matched healthy controls were enrolled in this multi-center study. Serum hBD2 and LL37 levels were determined with the enzyme-linked immunosorbent assay method.
  
  
  RESULTS
  Sixty-three post-infectious BO patients and 65 healthy children (median age 73 ± 55 and 78.74 ± 36.32 months, respectively) were enrolled in the study. The mean of hBD2 levels in patients and the control group were 1.06 ± 0.24 and 0.67 ± 0.72 ng/mL, respectively (P < 0.001). The mean of LL-37 levels in patients and the control group were 72.13 ± 29.06 and 50.10 ± 21.98 ng/mL, respectively (P < 0.001). No correlation was found between these AMPs levels and chronological age, age at the time of diagnosis, gender, Z-scores of weight and length, hospitalization numbers, the disease history before diagnosis and 25-OH D vitamin levels.
  
  
  CONCLUSIONS
  This is the first study to demonstrate the higher levels of serum hBD2 and LL-37 levels in paediatric post-infectious BO patients. These AMPs may have important roles in the immune systems and pathogenesis of these patients.
authors.affiliation: Division of Pediatric Pulmonology, Bezmialem Vakif University, Istanbul, Turkey.
authors.forename: Ahmet Hakan
authors.initials: AH
authors.lastname: Gedik
authors.affiliation: Division of Pediatric Pulmonology, Bezmialem Vakif University, Istanbul, Turkey.
authors.forename: Erkan
authors.initials: E
authors.lastname: Cakir
authors.affiliation: Division of Pediatric Pulmonology, Marmara University, Istanbul, Turkey.
authors.forename: Yasemin
authors.initials: Y
authors.lastname: Gokdemir
authors.affiliation: Division of Pediatric Pulmonology, Kocaeli University, Istanbul, Turkey.
authors.forename: Zeynep Seda
authors.initials: ZS
authors.lastname: Uyan
authors.affiliation: Department of Biochemistry, Bezmialem Vakif Univeristy, Istanbul, Turkey.
authors.forename: Abdurrahim
authors.initials: A
authors.lastname: Kocyigit
authors.affiliation: Department of Pediatrics, Bezmialem Vakif University, Istanbul, Turkey.
authors.forename: Emel
authors.initials: E
authors.lastname: Torun
authors.affiliation: Division of Pediatric Pulmonology, Marmara University, Istanbul, Turkey.
authors.forename: Bulent
authors.initials: B
authors.lastname: Karadag
authors.affiliation: Division of Pediatric Pulmonology, Marmara University, Istanbul, Turkey.
authors.forename: Refika
authors.initials: R
authors.lastname: Ersu
authors.affiliation: Division of Pediatric Pulmonology, Marmara University, Istanbul, Turkey.
authors.forename: Fazilet
authors.initials: F
authors.lastname: Karakoc
mesh_terms: D023181:Antimicrobial Cationic Peptides; D001989:Bronchiolitis Obliterans / Q000378:metabolism*; D054804:Cathelicidins / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D015854:Up-Regulation; D023083:beta-Defensins / Q000097:blood*
chemical_list: D023181:Antimicrobial Cationic Peptides; D054804:Cathelicidins; C106641:DEFB4A protein, human; D023083:beta-Defensins
keywords: antimicrobial peptide-bronchiolitis obliterans-cathelicidin-child-defensin