Constitutive knockdown of Napsin A does not result in a fibrotic lung phenotype in mice

Introduction: Napsin A (Napsa) is an aspartic protease present in alveolar epithelial type 2 cells (AECII) and essential for posttranslational protein processing of surfactant protein (SP)-B. Mutation in surfactant proteins have been linked to interstitial lung disease and we recently observed an abnormal accumulation of unprocessed SP-B and induction of an apoptotic endoplasmic reticulum (ER)-stress response in patients with sporadic IPF. In this study we assessed whether deletion of Napsa in mice results in surfactant dysfunction, ER stress induction and consecutive development of fibrosis. Methods: Constituti…