Sex-determining region Y-box 2-positive alveolar cells are responsive to bleomycin-induced lung injury

As an important barrier,the pulmonary alveolar epithelium plays an important role in lung gas exchange and host defense.The alveolar epithelium is mainly comprised of alveolar type I(AT1)and type II(AT2)cells that are tightly connected to maintain the integrity of the alveolar epithelium.There are several kinds of stem/progenitor cells capable of repairing the adult alveolar epithelium in response to various injuries.Kim and colleagues identified bronchioalveolar stem cells(BASCs)that are capable of differentiating into alveolar cells and airway cells.[1]In addition,a subset of alveolar cells expressing the laminin receptorα6β4 but not surfactant protein C(SPC)was able to regenerate into AT2 cells upon bleomycin-induced lung injury.[2]Rare keratin 5-positive basal cells give rise to alveolar epithelial lineages after influenza infection.[3,4]Sex-determining region Y-box 2(Sox2)is a transcription factor that maintains and regulates self-renewal and pluripotency in embryonic stem cells.[5]The functional roles of Sox2 in the repair of alveolar epithelium injuries remain unknown.This study aimed to investigate whether the alveolar cells expressing Sox2 are involved in alveolar epithelial repair.