贝伐珠单抗可减轻X线全脑照射小鼠脑血管及血脑屏障损伤

Bevacizumab alleviates damage of capillaries and blood-brain barrier in whole-brain irradiation mice

目的探讨X线全脑照射小鼠经贝伐珠单抗（BVZ）干预后其脑血管及血脑屏障的改变。方法6-7周龄雄性C57BL小鼠按随机数字表法分为正常对照组（n=25）、BVZ组（n=25）、单纯照射组（n=25）。正常对照组小鼠不进行X线全脑照射及给药处理。单纯照射组及BVZ组小鼠麻醉后采用RS2000型X线生物辐照仪照射脑部（照射总剂量30 Gy，分3周照射），且BVZ组、单纯照射组小鼠在首次X线全脑照射同一天起分别腹腔注射10 mg/kg BVZ溶液或等量生理盐水（连续给药10周）。于首次X线全脑照射后11周时取材，采用HE染色观察小鼠脑血管病理改变，采用Western blotting检测小鼠脑组织血管内皮生长因子（VEGF）蛋白表达，采用伊文氏蓝（EB）染色评估小鼠血脑屏障损伤程度，采用免疫荧光双标染色检测小鼠脑组织血管性血友病因子（vWF）、紧密连接蛋白-1（ZO-1）表达。结果与正常对照组VEGF蛋白表达水平、脑组织EB含量[（9.66±0.73） μg/mL]、ZO-1/vWF比值（0.92±0.08）相比，单纯照射组、BVZ组VEGF蛋白表达水平、脑组织EB含量[（16.90±2.15） μg/mL、（12.29±0.96） μg/mL]均明显增高，ZO-1/vWF比值（0.46±0.18、0.75±0.11）均明显降低，差异均有统计学意义（P〈0.05）；与单纯照射组相比，BVZ组VEGF蛋白表达水平、脑组织EB含量明显降低，ZO-1/vWF比值明显增高，差异均有统计学意义（P〈0.05）。结论BVZ可通过降低VEGF表达水平，从而减轻X线全脑照射后小鼠脑血管及血脑屏障的损伤程度。

Objective To investigate the effect of bevacizumab （BVZ） on cerebral vessel and blood brain barrier changes in whole-brain irradiation mice. Methods Seventy-five male mice aged 6-7 weeks were randomly divided into normal control group, BVZ group and radiation group （n=25）. Mice from normal control group were without whole-brain irradiation or drug administration. Mice from BVZ group and radiation group were accepted fraetionated cranial irradiation at a total dose of 30 Gy by X-ray. Mice from BVZ group and radiation group were intraperitoneally injected with 10 mg/kg BVZ solution or equivalent normal saline （10 weeks continuously） at the beginning of the first X-ray whole-brain irradiation. Eleven weeks aider the first irradiation, HE staining was used to observe cerebrovascular pathological changes; Western blotting was used to test vascular endothelial growth factor （VEGF） protein expression; Evan Blue （EB） staining was used to assess the blood-brain barrier damage, and immunofluorescence staining was used to test the von willebrand factor （vWF） and tight junction protein-1 （ZO-1） expressions. Results The VEGF protein expression level and brain tissue EB content （[9.66±0.73] μg/mL） in the normal control group were significantly increased as compared with those in the radiation group and BVZ group （[16.90±2.15] μg/mL and [12.29±0.96] μg/mL, P〈0.05）, but ZO-1/vWF ratio （0.92±0.08） in normal control group was significantly decreased as compared with that in the radiation group and BVZ group （0.46±0.18 and 0.75±0.11, P〈0.05）. As compared with the radiation group, BVZ group had significantly reduced VEGF protein expression and EB level in the brain tissues, and had significantly increased ZO-1/vWF ratio （P〈0.05）. Conclusion BVZ decreases the quantity of VEGF in brain tissues and alleviates the continuous damage of the brain vessels and blood brain barrier in whole-brain irradiation mice.