Synchrotron microbeam radiation therapy (MRT) is a preclinical irradiation technique which could be used to treat intracranial malignancies. The goal of this work was to discern differences in gene expression and the predicted regulation of molecular pathways in the brainstem after MRT versus synchrotron broad-beam radiation therapy (SBBR). Healthy C57BL/6 mice received whole-head irradiation with median acute toxic doses of MRT (241 Gy peak dose) or SBBR (13 Gy). Brains were harvested 4 and 48 h postirradiation and RNA was extracted from the brainstem. RNA-sequencing was performed to identify differentially expressed genes (false discovery rate < 0.01) relative to nonirradiated controls and significantly regulated molecular pathways and biological functions were identified (Benjamini-Hochberg corrected P < 0.05). Differentially expressed genes and regulated pathways largely reflected a pro-inflammatory response 4 h after both MRT and SBBR which was sustained at 48 h postirradiation for MRT. Pathways relating to radiation-induced viral mimicry, including HMGB1, NF-κB and interferon signaling cascades, were predicted to be uniquely activated by MRT. Local microglia, as well as circulating leukocytes, including T cells, were predicted to be activated by MRT. Our findings affirm that the transcriptomic signature of MRT is distinct from broad-beam radiotherapy, with a sustained inflammatory and immune response up to 48 h postirradiation.

同步加速器微束放射治疗 (MRT) 是一种临床前照射技术，可用于治疗颅内恶性肿瘤。这项工作的目标是辨别 MRT 与同步加速器宽束放射治疗 (SBBR) 后基因表达的差异和脑干中分子通路的预测调节。健康的 C57BL/6 小鼠接受了中等急性毒性剂量的 MRT（241 Gy 峰值剂量）或 SBBR（13 Gy）的全头照射。在照射后 4 和 48 小时收获大脑，并从脑干中提取 RNA。进行 RNA 测序以鉴定相对于未辐照对照的差异表达基因（错误发现率 < 0.01），并鉴定出显着调节的分子途径和生物学功能（Benjamini-Hochberg 校正P< 0.05)。差异表达的基因和调节通路在很大程度上反映了 MRT 和 SBBR 后 4 小时的促炎反应，这在 MRT 照射后 48 小时持续。与辐射诱导的病毒模拟相关的通路，包括 HMGB1、NF-κB 和干扰素信号级联，预计会被 MRT 唯一激活。局部小胶质细胞以及循环白细胞，包括 T 细胞，预计会被 MRT 激活。我们的研究结果证实，MRT 的转录组学特征与宽束放疗不同，在放疗后 48 小时内具有持续的炎症和免疫反应。