Usual interstitial pneumonia and smoking-related interstitial fibrosis display epithelial to mesenchymal transition in fibroblastic foci - 11/09/14
Summary |
Background |
Fibroblastic foci (FF) are a major histological feature of usual interstitial pneumonia (UIP) in idiopathic pulmonary fibrosis (IPF) and collagen vascular diseases (non-IPF). In addition, FF are occasionally associated with smoking-related interstitial fibrosis (SRIF). Recent studies have suggested a role for epithelial to mesenchymal transition (EMT) in pulmonary fibrogenesis.
Methods |
Here, we investigated whether EMT was present in patients with IPF (n = 19), non-IPF (n = 17), and SRIF (n = 16) using morphometric immunohistochemistry, electron microscopy, and confocal microscopy. All patients had received lung biopsies or lobectomies for lung cancer.
Results |
IPF and non-IPF patients displayed restrictive lung function patterns, whereas those with SRIF presented mixed patterns. Cells within FF presented high number of alpha-smooth muscle actin (αSMA)-staining cells; however, the foci of IPF patients showed comparatively lower number. Moreover, colocalization of thyroid transcription factor-1 (TTF1) and αSMA within FF showed low number of staining cells for IPF and SRIF in comparison to non-IPF (p < 0.01). Nevertheless, all groups displayed colocalization of high rate of TTF1+-cells and low rate of αSMA+-cells within hyperplastic epithelioid cells in FF. Also, we observed areas with low proportion of TTF1+cells and αSMA+cells, which were present in SRIF and non-IPF more often than IPF (p < 0.001). Electron microscopy revealed small breaks in the alveolar basal lamina, which allowed epithelioid cells to directly contact the collagenous matrix and fibroblasts. Three-dimensional reconstruction revealed intense αSMA staining within some epithelioid cells, suggesting that they had gained a mesenchymal phenotype.
Conclusions |
These findings constitute the first report of EMT in SRIF and suggest that EMT occurs more prominently in SRIF and non-IPF than IPF.
Le texte complet de cet article est disponible en PDF.Keywords : Epithelial-mesenchymal transition, Usual interstitial pneumonia, Idiopathic pulmonary fibrosis, Smoking-related interstitial fibrosis, Double-staining immunohistochemistry
Plan
Vol 108 - N° 9
P. 1377-1386 - septembre 2014 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.
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