Systemic sclerosis and idiopathic interstitial pneumonia: histomorphometric differences in lung biopsies.
OBJECTIVE
The aim of this study was to examine the parenchymal and extracellular matrix remodeling process in two histologic patterns-nonspecific interstitial pneumonia (NSIP) and usual interstitial pneumonia (UIP)-in cases of idiopathic and sclerosis/systemic sclerosis (SSc)-associated interstitial pneumonia.


METHODS
We examined 15 cases of idiopathic NSIP, 10 cases of idiopathic UIP, 5 cases of SSc-UIP and 9 cases of SSc-NSIP. In the lung parenchyma, epithelial cells, endothelial cells and myofibroblasts were evaluated by immunohistochemical staining, whereas histochemical staining was used in order to evaluate collagen/elastic fibers in the extracellular matrix.


RESULTS
The percentage of surfactant protein A-positive epithelial cells was significantly greater in idiopathic NSIP than in SSc-NSIP, as well as being greater in idiopathic UIP than in SSc-UIP. Idiopathic NSIP and idiopathic UIP presented significantly higher immunoexpression of alpha smooth muscle actin in myofibroblasts than did SSc-NSIP and SSc-UIP. The percentage of CD34 endothelial cells in the pulmonary microvasculature was significant lower in idiopathic UIP than in SSc-UIP. The density of collagen fibers was significantly greater in idiopathic NSIP and idiopathic UIP than in SSc-NSIP and UIP. In contrast, the elastic fiber density was significantly lower in idiopathic UIP than in SSc-UIP.


CONCLUSIONS
Increased collagen synthesis, destruction of elastic fibers, high myofibroblast proliferation and poor microvascularization might represent a remodeling process found in idiopathic interstitial pneumonia, whereas the reverse might represent a repair process in SSc-associated interstitial pneumonia.
Parra
Edwin Roger
ER
University of São Paulo School of Medicine, CEP 01246-903, São Paulo, Brazil. erparra20003@yahoo.com.br
Otani
Leandro Hideki
LH
de Carvalho
Erika Franco
EF
Ab'Saber
Alexandre
A
Capelozzi
Vera Luiza
VL
D001706:Biopsy; D004547:Elastic Tissue / Q000473:pathology*; D005109:Extracellular Matrix / Q000737:chemistry / Q000473:pathology*; D024022:Fibrillar Collagens / Q000032:analysis*; D006801:Humans; D054988:Idiopathic Interstitial Pneumonias / Q000150:complications / Q000473:pathology*; D012595:Scleroderma, Systemic / Q000150:complications / Q000473:pathology*
D024022:Fibrillar Collagens