Purpose: Epithelial cell damage is a crucial component of the pathogenesis of acute lung injury (ALI). Neutrophil elastase (NE) is a well-known key enzyme for tissue injury caused by activated neutrophils, such as in ALI. In addition, extracellular histones are known to display significant cytotoxic effects, which may result in the further release of DAMPs leading to enhanced inflammation and the cell/tissue damages in various organs. The role of phosphatidylinositol-3-kinase (PI3K)-delta in respiratory epithelium, unlike in inflammatory cells, remains unknown. Methods: In this study, using scanning electron microscope (SEM), we aimed to evaluate the tissue damages of the respiratory epithelium in LPS-induced ALI and to define the role of PI3K-delta isoform in the production of NE and extracellular histone 1 (H1) linked to the respiratory epithelial damages. Results: Our results showed that LPS-instilled mice showed typical features of ALI; pulmonary neutrophilia, vascular leakage, and nuclear translocation of nuclear factor-κB (NF-κB) and PI3K-delta activation. Confocal microscopic analysis revealed that the production and releases of NE and H1 proteins were significantly increased in lung tissues and pulmonary neutrophils. Interestingly, SEM images revealed that the respiratory epithelium was damaged severely after LPS instillation exhibiting decreased numbers of epithelial cells, loss of cilia, the epithelial disarrangement, and the massive amount of thick mucus layer with the irregular surface. The treatment with PI3K-delta inhibitor, IC87114 restored the damaged respiratory epithelium on SEM images with a significant reduction of the production of NE and H1 in the lung from LPS-instilled mice. Besides, IC87114 substantially improved the LPS-induced ALI compared to the mice treated with vehicle only. Conclusion: These findings suggest that PI3K-delta signaling activation can be a pathogenic contributor to LPS-induced pulmonary neutrophilic inflammation, at least in part, through the production of NE and H1 which may destroy respiratory epithelium.