Background
Idiopathic pulmonary fibrosis is a severe and deadly form of diffuse parenchymal lung disease and treatment options are few. Alveolar epithelial type 2 (AEC2) cell senescence is implicated in the pathogenies of IPF. A major bioactive compound from the traditional Chinese medicine Fructus arctii, arctiin (ARC) has robust anti-inflammatory, anti-senescence, and anti-fibrosis functions. However, the potential therapeutic effects of ARC on IPF and the underlying mechanisms involved are still unknown.
Conclusion
Our data suggest that the p38/p53/p21 signaling axis plays a pivotal role in AEC2 senescence in pulmonary fibrosis. The p38/p53/p21 signaling axis inhibition by ARC@DPBNPs provides an innovative approach to treating pulmonary fibrosis in clinical settings.
Methods
First of all, ARC was identified as an active ingredient by network pharmacology analysis and enrichment analysis of F. arctii in treating IPF. We developed ARC-encapsulated DSPE-PEG bubble-like nanoparticles (ARC@DPBNPs) to increase ARC hydrophilicity and achieve high pulmonary delivery efficiency. C57BL/6 mice were used to establish a bleomycin (BLM)-induced pulmonary fibrosis model for assessing the treatment effect of ARC@DPBNPs on lung fibrosis and the anti-senescence properties of AEC2. Meanwhile, p38/p53 signaling in AEC2 was detected in IPF lungs, BLM-induced mice, and an A549 senescence model. The effects of ARC@DPBNPs on p38/p53/p21 were assessed in vivo and in vitro.
Results
Pulmonary route of administration of ARC@DPBNPs protected mice against BLM-induced pulmonary fibrosis without causing significant damage to the heart, liver, spleen, or kidney. ARC@DPBNPs blocked BLM-induced AEC2 senescence in vivo and in vitro. The p38/p53/p21 signaling axis was significantly activated in the lung tissues of patients with IPF, senescent AEC2, and BLM-induced lung fibrosis. ARC@DPBNPs attenuated AEC2 senescence and pulmonary fibrosis by inhibiting the p38/p53/p21 pathway.