Interstitial lung disease: physiopathology in the context of lung growth

Interstitial lung diseases (ILDs) in children represent a heterogeneous group of respiratory disorders characterized by derangements of the alveolar walls. The key pathologic feature of ILDs is the altered repair of the alveolar surface after injury with a marked disruption in the integrity of the epithelium and, consequently, a dysregulated communication between epithelial and mesenchymal pulmonary components. Concomitant to the loss of cell-cell contact, epithelial cells undergo a process called epithelial to mesenchymal transition and acquire a mesenchymal identity. Among the factors involved in disease progression, transforming growth factor-β has been identified as a master switch in the induction of fibrosis. This article reviews recent advances in the understanding of the mechanisms involved in the pathogenesis of ILDs, and provides information on their adaptation in the context of lung growth.