FIGURE 6 from Uncovering the Protective Neurologic Mechanisms of Hypofractionated FLASH Radiotherapy

FLASH irradiation protected against prolonged inflammation found in CONV mice, 6 months after irradiation. Representative images of reactive microglia CD68 (red) and DAPI (blue) in the male mouse hippocampus (A) and representative images of IBA1 (green), TLR4 (red), and DAPI (blue; Scale bar = 100 μm; B). C, Quantification of CD68 immunofluorescence in the hippocampus and medial prefrontal cortex. Male (left) and female (right) mice exposed to FLASH-RT exhibit no significant change in CD68 expression while CONV mice expressed a neuroinflammatory response. D, Quantification of IBA1 and TLR4 colocalization in the hippocampus and medial prefrontal cortex. Male and female mice exhibited decreased levels of the neuroinflammatory mediator TLR4 when compared with CONV irradiation. E, Inflammatory cytokines measured using ELISA. IL1α exhibited elevated expression after CONV-RT exposure when compared with controls while FLASH induced no changes. No significant changes were observed in TNFα or IL1β. All data were analyzed using a one-way ANOVA followed by Bonferroni multiple comparison test (n = 4/sex/treatment, two sections analyzed/region/animal). *, P ≤ 0.05; **, P ≤ 0.01; ****, P ≤ 0.0001.