Cai Yingyuan, Liu Xinfeng, Chen Weixian, Wang Zhenzhen, Xu Gelin, Zeng Yanying, Ma Yuping
Department of Geratology, the First Affiliated Hospital of Nanjing Medical University, 300# Guangzhou Road, Nanjing 210029, Jiangsu Province, China.
Department of Neurology, Jinling Hospital, Nanjing University School of Medicine, 305 East Zhongshan Road, Nanjing 210002, Jiangsu Province, China.
Exp Neurol. 2015 Apr;266:120-6. doi: 10.1016/j.expneurol.2015.02.013. Epub 2015 Feb 20.
Transforming growth factor-beta1 (TGF-β1) is well known to promote extracellular matrix accumulation. Recent studies demonstrated that TGF-β1 protects against blood-brain barrier (BBB) disruption in the condition of inflammatory pain and stroke. In the present study, we investigated whether TGF-β1 can maintain BBB integrity and prevent hemorrhagic transformation (HT) after recombinant tissue plasminogen activator (rt-PA) treatment in a rat model of thromboembolic middle cerebral artery occlusion (MCAO). Three hours after MCAO, rats were given saline, rt-PA alone or rt-PA combined with TGF-β1 intravenously. Animals were sacrificed 24h after surgery. HT was calculated as hemorrhagic score. Evans blue dye extravasation was measured for BBB disruption. Basement membrane damage was observed by electron microscopy and quantified by collagen IV and laminin immunostaining. Gelatin zymography was used to measure the activities of matrix metalloproteinase (MMP)-2 and MMP-9. Western blot was performed for the expressions of MMP-2, MMP-9 and plasminogen activator inhibitor type-1 (PAI-1). Rats treated with rt-PA showed elevations in basement membrane damage, BBB disruption and HT. These phenomena were reduced in rats treated by TGF-β1. We also showed that TGF-β1 inhibited rt-PA mediated induction of MMP-2 and MMP-9. Meanwhile, TGF-β1 upregulated PAI-1 expression which was reduced by rt-PA. Taken together, these results suggest that TGF-β1 can reduce rt-PA induced basement membrane degradation, BBB disruption and HT. One possible mechanism is associated with the elevation of PAI-1. Suppression of MMP-2 and MMP-9 elevated by rt-PA may be another mechanism contributing to the protective effects of TGF-β1.
转化生长因子-β1（TGF-β1）以促进细胞外基质积累而闻名。最近的研究表明，TGF-β1在炎性疼痛和中风的情况下可防止血脑屏障（BBB）破坏。在本研究中，我们调查了在血栓栓塞性大脑中动脉闭塞（MCAO）大鼠模型中，TGF-β1是否能在重组组织型纤溶酶原激活剂（rt-PA）治疗后维持BBB完整性并预防出血转化（HT）。MCAO后3小时，大鼠静脉注射生理盐水、单独的rt-PA或rt-PA与TGF-β1联合使用。术后24小时处死动物。HT以出血评分计算。测量伊文思蓝染料外渗以评估BBB破坏情况。通过电子显微镜观察基底膜损伤，并通过IV型胶原和层粘连蛋白免疫染色进行定量。采用明胶酶谱法测量基质金属蛋白酶（MMP）-2和MMP-9的活性。进行蛋白质免疫印迹法检测MMP-2、MMP-9和纤溶酶原激活物抑制剂-1（PAI-1）的表达。接受rt-PA治疗的大鼠基底膜损伤、BBB破坏和HT均有所增加。而TGF-β1治疗的大鼠中这些现象有所减轻。我们还表明，TGF-β1抑制rt-PA介导的MMP-2和MMP-9的诱导。同时，TGF-β1上调了被rt-PA降低的PAI-1表达。综上所述，这些结果表明TGF-β1可以减少rt-PA诱导的基底膜降解、BBB破坏和HT。一种可能的机制与PAI-1的升高有关。抑制rt-PA升高的MMP-2和MMP-9可能是TGF-β1发挥保护作用的另一种机制。
