School of Clinical Medicine, Shandong Second Medical University, Weifang, 261053, Shandong, China.
Department of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, NO.440 Ji Yan Road, Jinan, 250117, Shandong, China.
Sci Rep. 2024 Apr 8;14(1):8193. doi: 10.1038/s41598-024-58831-z.
The study aimed to determine the specific relative biological effectiveness (RBE) of various cells in the hippocampus following proton irradiation. Sixty Sprague-Dawley rats were randomly allocated to 5 groups receiving 20 or 30 Gy of proton or photon irradiation. Pathomorphological neuronal damage in the hippocampus was assessed using Hematoxylin-eosin (HE) staining. The expression level of NeuN, Nestin, Caspase-3, Olig2, CD68 and CD45 were determined by immunohistochemistry (IHC). The RBE range established by comparing the effects of proton and photon irradiation at equivalent biological outcomes. Proton induced more severe damage to neurons than photon, but showed no difference compared to photon. The RBE of neuron was determined to be 1.65. Similarly, both proton and proton resulted in more inhibition of oligodendrocytes and activation of microglia in the hippocampal regions than photon and photon. However, the expression of Olig2 was higher and CD68 was lower in the proton group than in the photon group. The RBE of oligodendrocyte and microglia was estimated to be between 1.1 to 1.65. For neural stem cells (NSCs) and immune cells, there were no significant difference in the expression of Nestin and CD45 between proton and photon irradiation (both 20 and 30 Gy). Therefore, the RBE for NSCs and immune cell was determined to be 1.1. These findings highlight the varying RBE values of different cells in the hippocampus in vivo. Moreover, the actual RBE of the hippocampus may be higher than 1.1, suggesting that using as RBE value of 1.1 in clinical practice may underestimate the toxicities induced by proton radiation.
本研究旨在确定质子辐照后海马体中不同细胞的特定相对生物效应（RBE）。将 60 只 Sprague-Dawley 大鼠随机分为 5 组，分别接受 20 或 30 Gy 的质子或光子照射。使用苏木精-伊红（HE）染色评估海马体的形态学神经元损伤。通过免疫组织化学（IHC）测定 NeuN、Nestin、Caspase-3、Olig2、CD68 和 CD45 的表达水平。通过比较等效生物学效应下质子和光子照射的效果来确定 RBE 范围。与光子相比，质子诱导的神经元损伤更严重，但与光子相比没有差异。神经元的 RBE 被确定为 1.65。同样，质子和光子都比光子和光子更能抑制海马区的少突胶质细胞和激活小胶质细胞。然而，与光子组相比，质子组的 Olig2 表达更高，CD68 表达更低。少突胶质细胞和小胶质细胞的 RBE 估计在 1.1 到 1.65 之间。对于神经干细胞（NSCs）和免疫细胞，质子和光子照射（20 和 30 Gy）之间，Nestin 和 CD45 的表达没有明显差异。因此，NSCs 和免疫细胞的 RBE 被确定为 1.1。这些发现突出了体内海马体不同细胞的 RBE 值存在差异。此外，海马体的实际 RBE 可能高于 1.1，这表明在临床实践中使用 1.1 的 RBE 值可能低估了质子辐射引起的毒性。
