Chen Feng, Ohashi Norifumi, Li Wensheng, Eckman Christopher, Nguyen Justin H
Department of Transplantation, Mayo Clinic, Jacksonville, FL 32224, USA.
Hepatology. 2009 Dec;50(6):1914-23. doi: 10.1002/hep.23203.
Brain edema in acute liver failure (ALF) remains lethal. The role of vasogenic mechanisms of brain edema has not been explored. We previously demonstrated that matrix metalloproteinase-9 (MMP-9) contributes to the pathogenesis of brain edema. Here, we show that MMP-9 mediates disruptions in tight junction (TJ) proteins in vitro and in brains of mice with ALF. We transfected murine brain endothelial cells (ECs) with MMP-9 complementary DNA (cDNA) using pc DNA3.1 (+)/Myc-His A expression vector. Tissue inhibitor of matrix metalloproteinases (TIMP-1) cDNA transfection or GM6001 was used to inhibit MMP-9. ALF was induced in mice with azoxymethane. Endogenous overexpression of MMP-9 in brain ECs resulted in significant degradation of the TJ proteins occludin and claudin-5. The alterations in TJ proteins correlated with increased permeability to fluorescein isothiocyanate-dextran molecules. The degradation of TJ proteins and the increased permeability were reversed by TIMP-1 and GM6001. Similar results were found when MMP-9 was exogenously added to brain ECs. We also found that TJ protein degradation was reversed with GM6001 in the brains of mice with ALF.
TJ proteins are significantly perturbed in brains of mice with ALF. These data corroborate the important role of MMP-9 in the vasogenic mechanism of brain edema in ALF.
急性肝衰竭（ALF）中的脑水肿仍然是致命的。脑水肿的血管源性机制的作用尚未得到探索。我们之前证明基质金属蛋白酶-9（MMP-9）促成了脑水肿的发病机制。在此，我们表明MMP-9在体外以及ALF小鼠的大脑中介导紧密连接（TJ）蛋白的破坏。我们使用pc DNA3.1(+)/Myc-His A表达载体用MMP-9互补DNA（cDNA）转染小鼠脑内皮细胞（ECs）。使用基质金属蛋白酶组织抑制剂（TIMP-1）cDNA转染或GM6001来抑制MMP-9。用偶氮甲烷诱导小鼠发生ALF。脑ECs中MMP-9的内源性过表达导致TJ蛋白闭合蛋白和Claudin-5的显著降解。TJ蛋白的改变与异硫氰酸荧光素-葡聚糖分子通透性增加相关。TJ蛋白的降解和通透性增加被TIMP-1和GM6001逆转。当将MMP-9外源性添加到脑ECs时也发现了类似结果。我们还发现GM6001可逆转ALF小鼠大脑中TJ蛋白的降解。
ALF小鼠大脑中的TJ蛋白受到显著干扰。这些数据证实了MMP-9在ALF脑水肿血管源性机制中的重要作用。
