Clinical significance of mTOR, ZEB1, ROCK1 expression in lung tissues of pulmonary fibrosis patients

BACKGROUND Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease of unknown causes. Three proteins (mammalian target of rapamycin, mTOR; zinc finger E-box-binding homeobox 1, ZEB1; Rho-associated, coiled-coil containing protein kinase 1, ROCK1) may be related to pulmonary fibrosis. However, they have not been assessed in human pulmonary fibrosis. We assessed the clinical significance of mTOR, ZEB1, and ROCK1 expression in human pulmonary fibrosis of usual interstitial pneumonia (UIP) pattern. METHODS The mTOR, ZEB1, and ROCK1 expression was evaluated by immunohistochemical staining of 30 surgical lung biopsy tissues from 26 IPF and 4 UIP pattern connective tissue disease related interstitial lung disease (CTD-ILD) patients. The expression scores correlated with the clinical features. RESULTS The mTOR, ZEB1 and ROCK1 mainly expressed in alveolar epithelial cells of UIP lungs. The histological fibrosis scores and lung function decline in the strong mTOR expression group were higher than those in the weak and intermediate expression group. Patients with positive ZEB1 expression had higher fibrosis scores and greater decline in carbon monoxide diffusion capacity (DLCO) than patients with negative ZEB1 expression. Patients with positive mTOR or ZEB1 expression had poorer prognosis than that of patients with negative mTOR or ZEB1 expression, although it was not statistically significant. ROCK1 was not associated with the studied clinicopathological features. CONCLUSIONS The mTOR and ZEB1 expression in pulmonary fibrosis patients significantly correlated with the fibrosis score and lung function decline, indicating that it may be related to the prognosis of pulmonary fibrosis. Further studies involving large numbers of homogeneous IPF patients are warranted.