Alveolar epithelial cell injury with Epstein-Barr virus upregulates TGFβ1 expression

Abstract

Idiopathic pulmonary fibrosis (IPF) is a refractory and lethal interstitial lung disease characterized by alveolar epithelial cells apoptosis, fibroblast proliferation, and ECM protein deposition. Epstein-Barr virus (EBV) has previously been localized to alveolar epithelial cells of IPF patients and is associated with a poor prognosis. In this study, we utilized a microarray-based differential gene expression analysis strategy to identify molecular drivers of EBV-associated lung fibrosis. Two cell lines, primary human alveolar epithelial cells type 2 and A549 cells, were infected with EBV. EBV lytic phase induction increased active and total transforming growth factor-beta1 (TGFbeta1) transcript expression in association with reduced cell proliferation and increased caspase 3/7 activity. Exposing EBV-infected cells to ganciclovir resulted in TGFbeta1 deregulation and reduced expression of EBV early response genes, BRLF1 and BZLF1. We targeted the BRLF1 and BZLF1 gene products, Rta and Zta, by silencing RNA, and this resulted in the normalization of TGFbeta1 transcript and cell proliferation levels. Our study using a viral cell line model complements existing human and animal model data and further provides evidence to suggest that viral epithelial cell injury may play a role in IPF.