title: Nitric acid-induced bronchiolitis in rats mimics childhood Bronchiolitis obliterans.
abstract: BACKGROUND
  Childhood bronchiolitis obliterans (CBO) is an infrequent but severe disease, characterized by persistent obstructive respiratory symptoms after an acute episode of bronchiolitis. Its etiology is mostly postviral, especially in developing countries. Pathologically, CBO is characterized as constrictive-type BO. The pathogenesis of this disease is poorly understood and there is no specific treatment. Animal models could help to better understand the sequence of events culminating in bronchiolar obliteration and serve as basis for experimental therapeutic research.
  
  
  OBJECTIVE
  In this study, we adapted the nitric acid (NA) technique to develop a suitable model to study CBO in rats.
  
  
  METHODS
  We have intratracheally instilled 0.5% NA or saline and studied the histological lesions on days 2, 7, 14 and 30. NA-instilled animals developed a sequence of bronchiolar lesions that included necrotizing bronchiolitis, proliferative (PROL) bronchiolar lesions and constrictive (CONS) bronchiolar lesions with bronchiectasis, mucostasis and macrophagic accumulation.
  
  
  RESULTS
  The frequency of PROL lesions decreased and that of the CONS lesions increased, with a statistically significant difference at the sacrifice days, except for day 7 (PROL vs. CONS lesions day 2: p = 0.001; PROL vs. CONS lesions day 7: p = 0.38; PROL vs. CONS lesions day 14: p < 0.001; PROL vs. CONS lesions day 30: p < 0.001).
  
  
  CONCLUSIONS
  We conclude that this model presents histological similarities with the histological picture of CBO, being suitable for further developmental and therapeutic experimental research in this field.
authors.affiliation: Department of Pediatrics, School of Medicine, São Paulo University, Avenida Dr. Arnaldo 455, 1st floor, São Paulo, SP 01246-903, Brazil.
authors.forename: Claudia L B
authors.initials: CL
authors.lastname: Costa
authors.forename: Graziela M G T
authors.initials: GM
authors.lastname: Spilborghs
authors.forename: Milton A
authors.initials: MA
authors.lastname: Martins
authors.forename: Paulo H N
authors.initials: PH
authors.lastname: Saldiva
authors.forename: Thais
authors.initials: T
authors.lastname: Mauad
mesh_terms: D000818:Animals; D001980:Bronchi / Q000473:pathology*; D001989:Bronchiolitis Obliterans / Q000503:physiopathology*; D002648:Child; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D008297:Male; D017942:Nitric Acid / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar
chemical_list: D017942:Nitric Acid