Serpin B4 isoform overexpression is associated with aberrant epithelial proliferation and lung cancer in idiopathic pulmonary fibrosis

Abstract

The aim of the study was to evaluate the role of Serpin B3/B4 in advanced idiopathic pulmonary fibrosis (IPF) patients, mainly focusing on epithelial proliferation. Lungs from 48 IPF patients (including cases with cancer or high-grade epithelial dysplasia) were studied and compared with other diffuse parenchymal diseases and normal lungs. Immunohistochemistry for Serpin B3/B4 and Ki-67 was quantified in all cases, distinguishing stained metaplastic cells. In IPF patients correlations between Serpin expression and several clinicopathological data, including fibrotic remodelling [fibrosis extension and transforming growth factor β expression (TGF-β)] were performed. Molecular analysis was used for Serpin isoform characterisation. In IPF patients Serpin B3/B4 and Ki-67 were significantly overexpressed in many metaplastic cells (mainly squamous type) compared to control cases. Higher Serpin B3/B4 was found in older patients and cases with more impaired respiratory function. Serpin B3/B4 expression was related to both TGF-β and Ki-67 and was higher in patients with cancer/high-grade dysplasia. Serpin B3 was expressed in all cases, whereas Serpin B4 was expressed only in IPF. Serpin B3/B4, particularly Serpin B4, appears to play an important role in aberrant epithelial proliferation. Evaluation of Serpin B3/B4 could have prognostic value in predicting disease progression, especially in patients with increased susceptibility to lung cancer.