ROLE OF PROGENITOR CELLS IN REGENERATION OF LUNG TISSUE FOLLOWING INFLUENZA INFECTION

Abstract

We established influenza-induced lung injury model to explore the cellular pathways of lung tissue repair. Quantitative immunohistochemical analysis was performed during the course of influenza infection and recovery. A novel cell type expressing the Alveolar type II cell (AT2) SPC was observed to be induced in bronchioles in the damaged areas of the lung. These cells, referred to as SPC+ bronchiolar epithelial cells (SBECs), could be genetically traced to originate from Clara cells. We demonstrated that SBECs form the tips of extending bronchioles and differentiate into AT2s during the regeneration of alveolar epithelium in a process similar to development of embryonic alveolar epithelium. Moreover, we obtained preliminary observations to elucidate differences between adult and aged mice in terms of lung tissue regeneration following injury, with an aim to shed light on the cause of the much more severe disease in the elderly.