缓激肽开放血瘤屏障过程中诱发快速耐受性的机制探讨

目的探讨缓激肽(bradykinin,BK)开放血瘤屏障过程中,HSF1和HSP70对BK诱发快速耐受性的影响。方法首先通过立体定向法接种C6细胞制备恶性胶质瘤大鼠模型。模型制备成功后,经颈内动脉缓慢小剂量给予缓激肽(或生理盐水)10μg.kg-1.min-1,动态观察肿瘤组织内热休克因子1(heatshockfactor1,HSF1)蛋白单体和三聚体的活性及热休克蛋白70(heatshockprotein70,HSP70)的表达(Westernblot法)。免疫组织化学技术检测血瘤屏障上紧密连接蛋白occludin的变化。利用伊文思蓝连续监测缓激肽处理后的C6恶性胶质瘤大鼠血瘤屏障的通透性,同时电镜观察血瘤屏障的病理学改变。结果缓激肽作用于C6大鼠后,紧密连接增宽,血瘤屏障通透性增加,伊文思蓝渗出量分别较对照组增加了5.19μg.g-1(0min),5.06μg.g-1(5min),11.35μg.g-1(10min,P<0.05),21.54μg.g-1(15min,P<0.01),12.81μg.g-1(30min,P<0.05),7.28μg.g-1(60min)。肿瘤组织内HSF1蛋白三聚体活性和HSP70蛋白的表达逐渐增加,且分别于处理后的5min和30min时达高峰(P<0.01,与对照组相比),最大值为对照组的2～3倍。免疫组化检测结果发现,处理后的C6动物,其血瘤屏障的紧密连接蛋白occludin表达减少,15min后逐渐增加。结论缓激肽作用于血瘤屏障后,激活了HSF1并促进了hsp70蛋白的表达。增加的hsp70可能通过发挥分子伴侣作用来修复紧密连接蛋白,进而诱发快速耐受性。

Mechanism of achyphylaxis by bradykinin in opening blood-brain barrier

Aim To assess the effect of heat shock factor-1(HSF1)and heat shock protein 70(HSP70)to tachyphylaxis by bradykinin in the opening blood-tumor barrier(BTB).Methods The C6 rat intracerebral glioma model was constructed by stereotactic implantation technique.Using western blotting method to continue monitoring the protein expression of HSF1 and HSP70 in tumor tissue after bradykinin acted on animals.The expression of occludin in tumor tissue were detected by immunohistochemistry method.Using Evans blue and electron microscope,respectively,detected the permeability and pathology of BTB after intracarotid infusion of bradykinin in C6 rats.Results Bradykinin increased the tight junction opening and the permeability of BTB in C6 animals,and the relative increments of EB were 5.19 μg·g-1(0 min),5.06 μg·g-1(5 min),11.35 μg·g-1(10 min,P<0.05),21.54 μg·g-1(15 min,P<0.01),12.81 μg·g-1(30 min,P<0.05),7.28 μg·g-1(60 min).After bradykinin effected on C6 rats,the activity of HSF1 trimer and protein expression of HSP70 were gradually increased and then reached the peak at 5 min and 10 min(maximum levels were 2～3-fold greater than control group,P<0.01,compared with control group).The expression of occludin decreased and reached the minimum value at 15 min,then increased.Conclusion Bradykinin activated HSF1 and induced the expression of HSP70 in tumor tissues.The increased hsp70 repaired tight junction proteins as a chaperone,and this process mediated tachyphylaxis by bradykinin in opening the BTB.These mechanisms may explain effects of HSF1 and HSP70 to tachyphylaxis by bradykinin in the opening Blood-brain barrier(BBB).