Mechanisms of Alveolar Type 2 Epithelial Cell Death During Acute Lung Injury

Diffuse alveolar epithelial cell (AEC) death occurs extensively during acute lung injury (ALI). Due to the limited proliferative capacity of alveolar type 1 epithelial (AT1) cells, the differentiation and regenerative capacity of alveolar type 2 epithelial (AT2) cells are required to restore the barrier function of AECs. However, during lung injury, AT1 cells are particularly susceptible to injury, and ATII cells die in the presence of severe or certain types of injury. This disruption ultimately results in a hindrance to the ability of AT2 cells to proliferate and differentiate into AT1 cells in time to repair the extensively damaged AECs. Therefore, understanding the mechanism of injury death of AT2 cells may be beneficial to reverse the above situation. This article reviews the main death modes of AT2 cells, including apoptosis, necrosis, necroptosis, pyroptosis, autophagic cell death, and ferroptosis. It compares the various forms of death, showing that various cell injury death modes have unique action mechanisms and partially overlapping pathways. Studying the mechanism of AT2 cell death is helpful in screening and analyzing the target pathway of AEC barrier function recovery. It opens up new ideas and strategies for preventing and treating ALI.