Wu J, Yang S, Xi G, Song S, Fu G, Keep R F, Hua Y
Medical School, Zhejiang University, Hangzhou, China.
Acta Neurochir Suppl. 2008;105:59-65. doi: 10.1007/978-3-211-09469-3_13.
Microglial activation and thrombin formation contribute to brain injury after intracerebral hemorrhage (ICH). Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1beta) are 2 major proinflammatory cytokines. In this study, we investigated whether thrombin stimulates TNF-alpha and IL-1beta secretion in vitro, and whether microglial inhibition reduces ICH-induced brain injury in vivo. There were 2 parts to this study. In the first part, cultured rat microglial cells were treated with vehicle, thrombin (5 and 10U/mL), or thrombin plus tuftsin (0.05 microg/mL), an inhibitor of microglia activation. Levels of TNF-alpha and IL-1beta in culture medium were measured by ELISA at 4, 8, and 24 h after thrombin treatment. In the second part of the study, rats received an intracerebral infusion of 100 microL autologous whole blood with or without 25 microg of tuftsin 1-3 fragment. Rats were killed at day 1 or day 3 for immunohistochemistry and brain water content measurement. We found that thrombin receptors were expressed in cultured microglia cells, and TNF-alpha and IL-1beta levels in the culture medium were increased after thrombin treatment. Tuftsin reduced thrombin-induced upregulation of TNF-alpha and IL-1beta. In vivo, microglia were activated after ICH, and intracerebral injection of tuftsin reduced brain edema in the ipsilateral basal ganglia (81.1 +/- 0.7% vs. 82.7 +/- 1.3% in vehicle-treated group; p < 0.05) after ICH. These results suggest a critical role of microglia activation in ICH-related brain injury.
小胶质细胞激活和凝血酶形成参与脑出血（ICH）后的脑损伤。肿瘤坏死因子-α（TNF-α）和白细胞介素-1β（IL-1β）是两种主要的促炎细胞因子。在本研究中，我们调查了凝血酶是否在体外刺激TNF-α和IL-1β分泌，以及小胶质细胞抑制是否在体内减轻ICH诱导的脑损伤。本研究分为两部分。在第一部分中，用溶剂、凝血酶（5和10U/mL）或凝血酶加吞噬素（0.05μg/mL，一种小胶质细胞激活抑制剂）处理培养的大鼠小胶质细胞。在凝血酶处理后4、8和24小时，通过酶联免疫吸附测定法（ELISA）测量培养基中TNF-α和IL-1β的水平。在研究的第二部分中，大鼠接受脑内注射100μL自体全血，伴或不伴有25μg吞噬素1-3片段。在第1天或第3天处死大鼠，进行免疫组织化学和脑含水量测量。我们发现凝血酶受体在培养的小胶质细胞中表达，凝血酶处理后培养基中TNF-α和IL-1β水平升高。吞噬素减少了凝血酶诱导的TNF-α和IL-1β上调。在体内，ICH后小胶质细胞被激活，脑内注射吞噬素减轻了ICH后同侧基底神经节的脑水肿（与溶剂处理组的82.7±1.3%相比，为81.1±0.7%；p<0.05）。这些结果表明小胶质细胞激活在ICH相关脑损伤中起关键作用。
