Endothelial Senescence-Associated Secretory Signaling Promotes Macrophage Extracellular Traps Formation and Contributes to the Exacerbation of Combined Lung Injury.

Radiation-induced lung injury (RILI) is a common complication of thoracic radiotherapy and can be critically exacerbated by pre-existing pulmonary inflammation, yet the synergistic mechanisms driving this pathology remain elusive. Using a murine model of combined lung injury induced by lipopolysaccharide (LPS) and thoracic irradiation (IR), we identified macrophage extracellular traps (METs), a type of web-like chromatin structure released by macrophages, rather than neutrophil extracellular traps (NETs), as a prominent pathogenic process. Mechanistically, the combination of LPS and irradiation induced an early endothelial senescence-associated phenotype and a CXC chemokine-enriched secretory profile. These signals engaged macrophage CXCR2, leading to p38/ERK pathway activation and reactive oxygen species (ROS) production that contributed to METs formation (METosis). Functionally, METs serve as potential dual-phase mediators, contributing to epithelial barrier disruption during acute injury and promoting epithelial-mesenchymal transition (EMT)-like epithelial remodeling, thereby potentially linking early inflammatory damage to subsequent fibrotic progression. Furthermore, we demonstrate that the bioactive compound Cordycepin exerts protective effects by suppressing p38/ERK pathway activation and attenuating METosis. Collectively, these findings support a potential endothelial senescence-associated secretory signaling-METosis axis, providing a novel mechanistic framework and candidate therapeutic strategies for managing high-risk radiation-induced lung injury.