FLASH Irradiation Modulates Immune Responses and Accelerates Lung Recovery: A Single-Cell Perspective

We performed single-cell RNA sequencing to analyze murine lung tissues exposed to either conventional dose rate (CONV) or FLASH radiation therapy (FLASH-RT). This approach elucidated distinct early immune responses in radiation-induced lung injury and revealed protective mechanisms specific to FLASH irradiation. Systematic characterization of over 135,000 cells within the pulmonary microenvironment uncovered critical immune and stromal cell dynamics that differentiate CONV and FLASH-RT responses. These findings provide mechanistic insights into FLASH-RT's biological effects and its potential clinical applications in thoracic oncology. Overall design: In this controlled experiment, C57BL/6J mice underwent whole-thorax irradiation at a dose of 17.8 Gy administered via either CONV or FLASH-RT. Lung specimens displaying characteristic radiation-induced injury phenotypes were systematically harvested during the acute phase (days 1 and 7 post-irradiation) from experimental cohorts (n=3 per group per time point). Age-matched sham-irradiated control groups underwent identical procedures without radiation exposure. Single-cell suspensions were generated through enzymatic dissociation of collected tissues and subsequently subjected to transcriptomic profiling using the 10x Genomics platform for single-cell RNA sequencing (scRNA-seq).