Simvastatin attenuates lung vascular leak and inflammation in a murine model of radiation-induced lung injury. Mus musculus

Background: Microvascular injury and increased vascular leakage are prominent features of the radiation-induced lung injury (RILI) which follows cancer–associated thoracic irradiation. The mechanisms of RILI are incompletely understood and therapeutic strategies to limit RILI are currently unavailable. We established a murine model of radiation pneumonitis in order to assess mechanism-based therapies for RILI-induced inflammation and vascular barrier dysfunction. Based on prior studies, we investigated the therapeutic potential of simvastatin as a vascular barrier protective agent in RILI. Methods: C57BL6/J mice receiving single dose exposure to 18, 20, 22, or 25 Gy, (n=10/group) were temporally assessed (4-12 weeks) for cellular and biochemical indices of injury present in both bronchoalveolar lavage (BAL) and lung tissues (cytokines, tyrosine nitrosylated proteins, leukocytes, extravasation of Evans blue dye or EBD, BAL albumin, histology). In specific experiments, irradiated mice (25Gy) received simvastatin (10 mg/kg) via intraperitoneal injection three times a week (pre and post irradiation) for 2- 6 weeks post irradiation. Results. Acute RILI evolved in a dose- and time-dependent fashion. Mice irradiated with 25Gy exhibited modest increases in BAL leukocytes but significant increases in BAL IL-6 (p=0.03) and TNF-a (p=0.01) at 4 weeks compared to controls. Increases in BAL nitrotyrosine content peaked at 6 weeks (p=0.03) and was accompanied by marked nitrotyrosine immunostaining in lung tissues. Indices of increase lung vascular permeability such as EBD extravasation, BAL protein and BAL albumin significantly increased over time beginning at 6 weeks (p>0.002 all) with histological evidence of severe edema formation and airway inflammation. Simvastatin- treated irradiated mice were noted to exhibit marked attenuation of vascular leak with significantly decreased BAL protein (p=0.01) and inflammatory cell infiltration (50% reduction). Conclusion: Simvastatin is a potentially important therapeutic strategy to limit RILI and may influence radiation associated morbidity and mortality. We used microarrays to detail the global programme of gene expression induced by radiation in Wild type and the protection of SIMVA Overall design: animals were treated by Vehical, Radiation (25Gy), SIMVA(10mg/kg), or both.

背景：伴随癌症相关胸部放疗发生的放射性肺损伤（radiation-induced lung injury, RILI）以微血管损伤与血管渗漏增加为核心特征。目前RILI的发病机制尚未完全阐明，且尚无获批的可有效限制RILI进展的治疗策略。本研究构建了放射性肺炎的小鼠模型，以评估针对RILI诱导的炎症与血管屏障功能障碍的机制导向治疗方案。基于既往研究基础，我们探究了辛伐他汀（simvastatin）作为RILI血管屏障保护剂的治疗潜力。
方法：将C57BL6/J小鼠单次暴露于18、20、22或25 Gy辐射剂量，每组10只，于照射后4~12周动态检测其支气管肺泡灌洗（bronchoalveolar lavage, BAL）液与肺组织中的损伤相关细胞与生化指标，包括细胞因子、酪氨酸硝化蛋白、白细胞计数、伊文思蓝染料（Evans blue dye, EBD）外渗量、BAL液白蛋白水平及组织病理学特征。在特定验证实验中，接受25 Gy辐射的小鼠于照射前后每周腹腔注射辛伐他汀（10 mg/kg），连续给药2~6周。
结果：急性放射性肺损伤的发生呈现明确的剂量与时间依赖性。与对照组相比，接受25 Gy辐射的小鼠在照射后4周时，BAL液中白细胞仅轻度升高，但IL-6（p=0.03）与TNF-α（p=0.01）水平显著升高。BAL液中硝基酪氨酸含量在照射后6周达到峰值（p=0.03），同时肺组织中可见硝基酪氨酸免疫染色显著增强。肺血管通透性相关指标（如EBD外渗量、BAL液总蛋白与白蛋白水平）自照射后6周起随时间显著升高（所有指标p>0.002），组织病理学可见严重肺水肿与气道炎症表现。接受辛伐他汀治疗的辐射小鼠可见血管渗漏显著减轻，BAL液总蛋白水平显著降低（p=0.01），炎症细胞浸润减少50%。
结论：辛伐他汀是一种极具潜力的限制RILI进展的治疗策略，或可改善辐射相关的发病率与死亡率。本研究通过基因芯片技术解析了野生型小鼠受辐射诱导的全局基因表达谱，以及辛伐他汀的保护作用。实验设计：受试动物分别接受溶剂对照（Vehicle）、25 Gy辐射、10 mg/kg辛伐他汀，或联合辐射与辛伐他汀处理。