Local and abscopal disturbances in mice exposed postnatally to ionizing radiation: Dose and brain irradiated volume complex effects

Consequences of children brain exposure to radiation (doses ≤ 2 Gy) are not clearly established. The advent of computed tomography scans use for head exploration as well as a recent increase in the use of interventional neuroradiology in pediatrics raised the need to improve our knowledge of these effects. To understand how irradiation may affect the developing brain, we previously developed models of either whole brain or hippocampal dorsal dentate gyrus irradiation in ten-day-old male mice (doses ≤ 2 Gy) and demonstrated some alterations in adult mice behavior and in hippocampal neurogenesis (Dos Santos 2018 ; Serrano 2021). The present study goal was to decipher the impact of those irradiations on the local and systemic inflammatory and immune response as well as on the establishment of gut microbiota. To tackle this goal, we used multianalyte technology to simultaneously determine the response of 32 cytokines and chemokines (brain and plasma) and performed complete blood count and fecal samples 16S rRNA sequencing. Our preliminary results showed complex dose and irradiated volume effects (i) from the dose of 0.25 Gy, with a significant increase in CXCL1, VEGF, IL2 and IL13 concentrations in the hippocampus in certain irradiation settings, (ii) in blood components and (iii) in the establishment of gut microbiota, suggesting abscopal effect of irradiation (1 Gy). Altogether our results provide new insights to evaluate systemic health risks of brain iradiation and to understand radiation-induced brain disorders. Soon, the role played by brain-body interactions in their physiopathology would be investigated.