Small airway remodeling in idiopathic interstitial pneumonias: a pathological study.
BACKGROUND
Few studies have addressed small airway (SA) histopathological changes and their possible role in the remodeling process in idiopathic interstitial pneumonias.


OBJECTIVE
To study morphological, morphometrical and immunohistochemical features of SA in idiopathic pulmonary fibrosis (usual interstitial pneumonia, UIP) and nonspecific interstitial pneumonia (NSIP).


METHODS
We analyzed SA pathology in lung biopsies from 29 patients with UIP and 8 with NSIP. Biopsies were compared with lung tissue from 13 patients with constrictive bronchiolitis (CB) as positive controls and 10 normal autopsied control lungs. We semi-quantitatively analyzed SA structure, inflammation, architectural features and the bronchiolar epithelial immunohistochemical expression of TGF-beta, MMP-2, 7, 9, and their tissue inhibitors (TIMP-1, 2).


RESULTS
Compared to controls, patients with UIP, NSIP and CB presented increased bronchiolar inflammation, peribronchiolar inflammation and fibrosis and decreased luminal areas. UIP patients had thicker walls due to an increase in most airway compartments. NSIP patients presented increased epithelial areas, whereas patients with CB had larger inner wall areas. All of the groups studied presented increased bronchiolar expression of MMP-7 and MMP-9, compared to the controls.


CONCLUSIONS
We conclude that SAs are pathologically altered and may take part in the lung-remodeling process in idiopathic interstitial pneumonias.
Figueira de Mello
George Castro
GC
Pathology Department, Hospital das Clinicas, University of Sao Paulo Medical School, São Paulo, Brazil.
Ribeiro Carvalho
Carlos Roberto
CR
Adib Kairalla
Ronaldo
R
Nascimento Saldiva
Paulo Hilário
PH
Fernezlian
Sandra
S
Ferraz Silva
Luiz Fernando
LF
Dolhnikoff
Marisa
M
Mauad
Thais
T
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D055745:Bronchioles / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D054988:Idiopathic Interstitial Pneumonias / Q000378:metabolism / Q000473:pathology*; D007150:Immunohistochemistry; D008297:Male; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D008875:Middle Aged; D019714:Tissue Inhibitor of Metalloproteinases / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D019714:Tissue Inhibitor of Metalloproteinases; D016212:Transforming Growth Factor beta; D020782:Matrix Metalloproteinases