The role of cGAS-STING pathway in the development of radiation-induced lung injury.

Background And Purpose: Radiation-induced lung injury (RILI) limits the efficacy of thoracic radiotherapy. However, the underlying mechanism of RILI remains unclear. cGAS-STING pathway is reported to be involved in the recognization of cytosolic dsDNA and various inflammatory diseases. This study aimed to investigate the role of cGAS-STING pathway in the development of RILI.

Materials And Methods: A pre-clinical mouse model of RILI was established by whole thorax irradiation and confirmed using H&E and Masson's trichrome staining. STING agonist (DMXAA) and antagonist(C-176) were administrated to modulate cGAS-STING pathway in vivo. Western blot and ELISA were used to determine the expression levels of different proteins.

Results: Quantitation analysis showed dsDNA accumulation in lung tissue and western blot showed the up-regulation of cGAS and STING protein level post-irradiation, indicating pathway activation. Histological evaluation showed that C-176 administration ameliorated radiation-induced pulmonary inflammation and fibrosis, while DMXAA exhibited contrary effects. In further in vitro study, the release of dsDNA induced by radiation led to the activation of cGAS-STING pathway in RAW 264.7 cells, resulting in the polarization into M1 phenotype and pro-inflammatory production.

Conclusion: In summary, our data demonstrated a link between cGAS-STING pathway and the development of RILI, indicating its potential application in clinic.