ACEI抑制肺血管重构防治放射性肺损伤机制的研究

Protection in radiation-induced pulmonary injury (RIPI) was becoming hot spot as results of RIPI regarded as an important dose-limiting toxicity during thoracic radiotherapy, and its pathogenesis was not clear due to pulmonary vascular remodeling tending to negligent, although oxygen free radical injury and inflammatory mediator definition were some good reasons for part. There, rat pulmonary injury models were established by a single dose of 20 Gy radiation to the right thorax, and exposed to different concentrations of angiotensin-converting enzyme inhibitor (ACEI) in different time phase, while as control. Injury of pulmonary vascular endothelium and pneumocyte was observed by morphology and immune-fluorescence staining, and chemokines in serum and cytokines in localized tissue (CCl2, TGF-β, IL-6, PGI2, TXA2,HP, et al) measured by RT-PCR, real time PCR or Western Bolting as well. Properly, NF-κB, Notch-1, the key of signal pathway related to activation of the alveolar macrophage, was assayed by knockout with anti-oligomers, while the correlation between alteration of NF-κB, Notch-1 and CCL2 probed. Finally, pulmonary vascular remodeling was evaluated by means of histopathology, immuno-histochemical staining, pathophysiology and hemodynamic change. it provides insight into strategies for protection with ACEI via the initial exploration of mechanism of pulmonary vascular remodeling in RIPI.

鉴于放射性肺损伤是胸部肿瘤放疗的限制性因素，因此对其防护作用的研究一直是肿瘤放疗的热点。既往关于氧自由基损伤及炎性介质介导的观点仅能部分说明其发生机制，而放射性肺损伤后血管重建的机理及可能潜在的治疗靶点未得到足够的重视。本项目拟以通过单次20Gy一侧肺野照射的Wister大鼠为研究对象，建立放射性肺损伤模型，经过不同浓度的ACEI处理后，观察模型中肺内皮细胞，肺泡细胞的损伤程度以及其内CCL2的mRNA转录水平和蛋白质水平的变化，和由此被调控的肺巨噬细胞活化相关的NF-κB及Notch-1信号通路的改变；同时检测不同时相肺损伤模型局部组织及血清中炎性因子（TGF-β、IL-6、PGI2、TXA2、HP等）；评估模型动物肺血管重构的组织病理学、组织化学和血管动力学的变化等；力图阐明ACEI通过抑制肺血管重构而防治放射性肺损伤的机理，为ACEI防治放射性肺损伤提供可靠的依据。

放射治疗是恶性肿瘤的主要治疗手段之一，约65%的肿瘤病人在整个治疗过程中会接受放疗。放射性肺炎是胸部肿瘤放射治疗的主要副反应，影像学上其发生率可达50%，但是其治疗方法及疗效有限且易复发。既往关于氧自由基损伤及炎性介质介导放射性肺损伤的观点仅能部分说明其发生机制，而放射性肺损伤后血管重建的机理及可能潜在的治疗靶点未得到足够的重视。本项目以单次20Gy右肺照射的Wistar大鼠为研究对象，建立放射性肺损伤模型，研究血管紧张素转化酶抑制剂（angiotension converting enzyme inhibitors, ACEI）在放射性肺损伤治疗中的作用及机制。主要研究内容包括：大鼠放射性肺损伤模型的建立与鉴定，ACEI对大鼠放射性肺损伤过程中肺内巨噬细胞趋化与活化的影响，ACEI 对大鼠放射性肺损伤过程中肺组织内血管重构的影响。本项目研究发现：在Wistar大鼠接受高剂量照射后其肺组织与血清中趋化性细胞因子配体-2（Chemokine ligand 2, CCL2）表达明显升高，在CCL2的趋化作用下巨噬细胞向损伤的肺组织聚集，ACEI能够抑制放射性肺损伤大鼠中CCL2的升高而抑制巨噬细胞在肺组织中聚集并且降低肺损伤相关细胞因子IL-6、TGF-β、PGI2和TXA2的产生，ACEI还抑制炎性信号通路NF-KB的活化并最终抑制肺血管重构及肺纤维化。本项目阐明ACEI 通过抑制肺血管重构而防治放射性肺损伤的机理，为ACEI防治放射性肺损伤提供可靠的依据，为临床推广ACEI防治放射性肺损伤提供理论准备。