TGF-ß1 promotes wound healing after ionizing radiation through the TGFß-SMAD canonical signaling pathway

Objective: Ionizing radiation (IR) therapy, commonly used in cancer treatment, has detrimental effects on the skin. When combined with surgical resection, IR leads to persistent wounds and forms a significant side effect, making wound healing difficult. This study aimed to understand the mechanisms underlying IR-induced wound damage and develop treatment methods. Approach: A mouse model of IR was created by exposing mice to 7Gy of radiation after skin excision. The temporal changes of epidermal stem cells (EPSCs) and wound healing were examined. RNA-seq analysis was performed on skin tissues to investigate regulatory mechanisms during the healing process. Topical application of TGFß was used to assess its impact on wound healing. Results: Mice in the IR group exhibited prolonged wound healing time, and the healing rate was significantly reduced. IR exposure decreased Ki67+/K14+ cells (proliferating EPSCs), reduced the expression levels of K14 and K15. The RNA-seq results revealed a significant decrease in epidermal stem cell-related genes following IR. Additionally, the TGFß-SMAD pathway exhibited temporal changes during the wound healing process, while pre-treatment with TGFß1 significantly promotes the healing of IR-induced wounds. Innovation: TGF-ß1 activated the TGFß-SMAD pathway and promotes wound healing after ionizing radiation. Conclusions: These findings indicate that IR diminishes the population of epidermal stem cells (EPSCs), thereby impeding the healing process by disrupting the TGFß-Smad pathway. However, the external application of TGFß1 to the wound area effectively improves IR-induced skin damage and exhibits promising therapeutic effects. These findings provide intervention targets and agents for the clinical applications. Overall design: To investigate the molecules involved in wound healing after IR, we employed RNA-seq analysis to examine the gene expression changes in the control and IR groups at 3, 6, 9 day post-injury.

研究目标：电离辐射（Ionizing radiation, IR）疗法是癌症治疗的常用手段，但会对皮肤产生有害影响。若联合手术切除治疗，电离辐射会引发难愈性创面，成为严重副作用，导致伤口愈合受阻。本研究旨在阐明电离辐射诱导创面损伤的潜在机制，并开发相应治疗方法。

研究方法：通过在皮肤切除后对小鼠施以7Gy辐射，构建电离辐射小鼠模型。观察表皮干细胞（epidermal stem cells, EPSCs）与伤口愈合的时序变化。对皮肤组织进行RNA测序（RNA-seq）分析，以探究愈合过程中的调控机制。采用局部给药方式给予转化生长因子β（transforming growth factor β, TGF-β），评估其对伤口愈合的影响。

研究结果：电离辐射组小鼠的伤口愈合时间延长，愈合速率显著降低。电离辐射暴露会减少Ki67+/K14+阳性细胞（增殖性表皮干细胞），下调K14与K15的表达水平。RNA测序结果显示，电离辐射后表皮干细胞相关基因的表达显著下调。此外，转化生长因子β-SMAD（TGF-β-SMAD）通路在伤口愈合过程中呈现时序性变化，而提前给予TGF-β1可显著促进电离辐射诱导创面的愈合。

创新点：TGF-β1可激活TGF-β-SMAD通路，从而促进电离辐射后的伤口愈合。

研究结论：本研究结果表明，电离辐射会减少表皮干细胞（EPSCs）的数量，并通过破坏TGF-β-Smad通路阻碍伤口愈合进程。然而，在创面局部外用TGF-β1可有效改善电离辐射诱导的皮肤损伤，展现出良好的治疗潜力。本研究结果为临床应用提供了干预靶点与治疗制剂。

整体实验设计：为探究电离辐射后伤口愈合相关的分子机制，本研究通过RNA测序分析，检测了对照组与电离辐射组小鼠在损伤后第3、6、9天的基因表达变化。