放射性肺损伤是胸部肿瘤放疗常见的严重并发症和剂量限制因素, 放射性肺损伤的发生也严重限制靶区放疗剂量的选择，降低了放疗效果。目前放射性肺损伤尚无有效防护和治疗药物，临床上主要用糖皮质激素控制放射性肺炎急性期症状，但它对晚期的肺纤维化没有明确疗效。目前的研究已经证明原花青素具有放射性损伤防护作用，又具有抑制肺癌、乳腺癌等胸部肿瘤增殖作用。理论上推测原花青素可以用做胸部肿瘤放疗用药：即起到肿瘤组织辐照杀伤协同又有对正常肺放射性损伤防护的双向作用。我们的在肺部荷瘤小鼠辐照模型的前期研究初步证实了这种双向作用，预实验结果还提示其双向作用机制可能与原花青素通过HR修复通路发挥放疗杀伤协同，而通过清除细胞毒性自由基、抗氧化而保护正常组织辐射损伤有关。本课题拟明确原花青素对胸部肿瘤放疗双向作用，并对肿瘤和正常组织作用差异机制进行初步研究。这将为原花青素作为胸部肿瘤放疗用药的应用研究奠定重要实验基础。

As a serious complication of radiotherapy, radiation injury on lung tissues could limit the application and delivery of radiation doses, which also reduces the therapeutic effect. However, there is no safe and effective drug for alleviating radiation damage on lung tissues. Nowadays, glucocorticoid is used to control severe symptoms of radiation pulmonitis, while it has no effect on lung fibrosis in the latter period. Recent studies have demonstrated that proanthocyanidins could protect normal lung tissues against radiation damage, and also exerted inhibitory roles in tumor proliferation. We hypothesized that proanthocyanidins could exert as a radioprotector which protects normal tissue from radiation damage when radiotherapy is delivered to chest tumors. Our previous data showed that proanthocyanidins obviously alleviated radiation damage on lung tissues, meanwhile the tumor growth was strongly inhibited. Preliminary experiment results also indicate that the Bidirectional Function mechanism may be related with radiotherapy synergistic killing by HR repair pathways play, and radioprotective effect in normal tissuey by scavenging cytotoxic oxygen free radicals. This study is aimed to clarify the radioprotective role of proanthocyanidins in normal tissues and also the radiosensitizing role in tumor growth, and to uncover the difference in mechanism between normal tissues and tumor. This will provide important experimental evidence for the application of proanthocyanidins as an effective protector against radiation damage on lung tissues during radiotherapy.