Machida Takashi, Dohgu Shinya, Takata Fuyuko, Matsumoto Junichi, Kimura Ikuya, Koga Mariko, Nakamoto Keiko, Yamauchi Atsushi, Kataoka Yasufumi
Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan.
Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan; BBB Laboratory, PharmaCo-Cell Co., Ltd., Nagasaki, Japan.
Neuroscience. 2017 May 14;350:146-157. doi: 10.1016/j.neuroscience.2017.03.026. Epub 2017 Mar 24.
Thrombin, an essential component in the coagulation cascade, participates in the pathogenesis of brain diseases, such as ischemic stroke, intracerebral hemorrhage, Alzheimer's disease and Parkinson's disease through blood-brain barrier (BBB) dysfunction. It is thought that the thrombin-matrix metalloproteinase (MMP)-9 axis is an important process in the pathogenesis of neurovascular disease, such as BBB dysfunction. We recently reported that brain pericytes are the most MMP-9-releasing cells in response to thrombin stimulation among the BBB-constituting cells. This thrombin-induced MMP-9 release is partially due to protease-activated receptor (PAR1), one of the specific thrombin receptors. Then, we evaluated the intracellular signaling pathways involved in MMP-9 release and the contribution of thrombin-reactive brain pericytes to BBB dysfunction. PKC activator evoked MMP-9 release from brain pericytes. The thrombin-induced MMP-9 release was inhibited by U0126, LY294002, Go6976, and Go6983. However, Go6976 decreased phosphorylation levels of PKCθ and Akt, and Go6983 decreased phosphorylation levels of PKCδ and extracellular signal-regulated kinase (ERK). Additionally, treatment of pericytes with thrombin or PAR1-activating peptide stimulated PKCδ/θ signaling. These substances impaired brain endothelial barrier function in the presence of brain pericytes. Brain pericytes function through two independent downstream signaling pathways via PAR1 activation to release MMP-9 in response to thrombin - the PKCθ-Akt pathway and the PKCδ-ERK1/2 pathway. These pathways participate in PAR1-mediated MMP-9 release from pericytes, which leads to BBB dysfunction. Brain pericytes and their specific signaling pathways could provide novel therapeutic targets for thrombin-induced neurovascular diseases.
凝血酶是凝血级联反应中的关键成分，通过血脑屏障（BBB）功能障碍参与多种脑部疾病的发病机制，如缺血性中风、脑出血、阿尔茨海默病和帕金森病。凝血酶-基质金属蛋白酶（MMP）-9轴被认为是神经血管疾病发病机制中的重要过程，如BBB功能障碍。我们最近报道，在构成BBB的细胞中，脑周细胞是对凝血酶刺激反应最强烈的MMP-9释放细胞。这种凝血酶诱导的MMP-9释放部分归因于蛋白酶激活受体（PAR1），它是一种特定的凝血酶受体。然后，我们评估了参与MMP-9释放的细胞内信号通路以及凝血酶反应性脑周细胞对BBB功能障碍的作用。蛋白激酶C（PKC）激活剂可诱导脑周细胞释放MMP-9。U0126、LY294002、Go6976和Go6983可抑制凝血酶诱导的MMP-9释放。然而，Go6976降低了PKCθ和Akt的磷酸化水平以及Go6983降低了PKCδ和细胞外信号调节激酶（ERK）的磷酸化水平。此外，用凝血酶或PAR1激活肽处理周细胞可刺激PKCδ/θ信号传导。在存在脑周细胞的情况下，这些物质会损害脑内皮屏障功能。脑周细胞通过PAR1激活的两条独立下游信号通路发挥作用，以响应凝血酶释放MMP-9——PKCθ-Akt通路和PKCδ-ERK1/2通路。这些通路参与PAR1介导的周细胞释放MMP-9，进而导致BBB功能障碍。脑周细胞及其特定信号通路可能为凝血酶诱导的神经血管疾病提供新的治疗靶点。
