Spampinato Simona Federica, Merlo Sara, Sano Yasuteru, Kanda Takashi, Sortino Maria Angela
Department of Biomedical and Biotechnological Sciences, Section of Pharmacology, University of Catania, Catania, Italy.
Department of Neurology and Clinical Neuroscience, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, Japan.
J Neurochem. 2017 Aug;142(3):464-477. doi: 10.1111/jnc.14068. Epub 2017 Jun 20.
The blood-brain barrier (BBB) plays an important role in the maintenance of the brain homeostasis, and its proper functions are warranted by the interplay between different cellular components (endothelial cells, astrocytes and pericytes). BBB dysfunctions in pathological conditions, and particularly in Alzheimer's disease, have been documented. Here, using an in vitroBBB model, the interaction between endothelial cells and astrocytes exposed to Aβ1-42 was investigated. Human endothelial cells, cultured in monolayer or co-cultured with astrocytes, were exposed to Aβ1-42 (2 μM for 18 h). Aβ induced dysfunction of endothelial barrier, as assessed by enhanced permeability to FITC-conjugated dextran and reduced expression of claudin-5; these modifications were observed in the co-culture model, but not in endothelial cells cultured in monolayer. Similarly, Aβ-induced damage at the barrier was observed when endothelial cells were challenged in the presence of conditioned medium generated by astrocytes previously exposed to Aβ (ACM Aβ). Endothelial barrier damages were associated with enhanced matrix metalloprotease 9 (MMP9) activity, known to mediate claudin-5 disruption. These events were not related to the direct effects played by Aβ on endothelial cells, but they were rather the consequence of Aβ-induced vascular endothelial growth factor (VEGF) expression in astrocytes. Indeed, when vascular endothelial growth factor expression was down-regulated in astrocytes, neither barrier properties or MMP9 expression in endothelial cells were affected after Aβ exposure both in the co-culture model or in the presence of ACM Aβ. These data point out the importance of astrocytes' mediation in inducing endothelial sensitivity to Aβ1-42
血脑屏障（BBB）在维持脑内环境稳定中发挥着重要作用，其正常功能由不同细胞成分（内皮细胞、星形胶质细胞和周细胞）之间的相互作用来保证。已有文献记载，在病理状态下，尤其是在阿尔茨海默病中，血脑屏障会出现功能障碍。在此，利用体外血脑屏障模型，研究了暴露于Aβ1-42的内皮细胞与星形胶质细胞之间的相互作用。将单层培养或与星形胶质细胞共培养的人内皮细胞暴露于Aβ1-42（2μM，持续18小时）。通过FITC标记葡聚糖通透性增强和claudin-5表达降低评估，Aβ诱导了内皮屏障功能障碍；这些改变在共培养模型中观察到，但在单层培养的内皮细胞中未观察到。同样，当内皮细胞在先前暴露于Aβ的星形胶质细胞产生的条件培养基（ACM Aβ）存在下受到挑战时，观察到了Aβ诱导的屏障损伤。内皮屏障损伤与基质金属蛋白酶9（MMP9）活性增强有关，已知MMP9可介导claudin-5破坏。这些事件与Aβ对内皮细胞的直接作用无关，而是Aβ诱导星形胶质细胞中血管内皮生长因子（VEGF）表达的结果。事实上，当星形胶质细胞中血管内皮生长因子表达下调时，在共培养模型或存在ACM Aβ的情况下，Aβ暴露后内皮细胞的屏障特性或MMP9表达均未受到影响。这些数据指出了星形胶质细胞介导在诱导内皮细胞对Aβ1-42敏感性方面的重要性
