Activated protein C reduces the ischemia/reperfusion-induced spinal cord injury in rats by inhibiting neutrophil activation
Activated protein C reduces the ischemia/reperfusion-induced spinal cord injury in rats by inhibiting neutrophil activation
复制标题
DOI：
10.1097/00000658-200008000-00018
复制
发表时间：
2000-08-01
影响因子：
9
通讯作者：
Kitamura, N
中科院分区：
文献类型：
--
作者：
Hirose, K;Okajima, K;Kitamura, N
目的探讨活化蛋白C （activated protein C， APC）是否通过抑制中性粒细胞的活化而减轻大鼠脊髓缺血后的损伤。背景资料化学性脊髓损伤是导致主动脉瘤修复术后截瘫的重要病理机制。活化的中性粒细胞在缺血/再灌注诱导的组织损伤的发展中起关键作用。最近，作者报道了APC，一种生理性抗凝剂，通过抑制中性粒细胞活化来预防脂多糖诱导的肺血管损伤。这些观察结果强烈表明，APC通过抑制中性粒细胞激活来减轻缺血/再灌注诱导的脊髓损伤。方法采用主动脉球囊导管诱导大鼠脊髓缺血。短暂缺血后，评估大鼠的生存和运动功能，缺血24小时后采用苏木精-伊红染色和2,3,5，-三苯四氮唑（TTC）染色对脊髓进行组织学检查。在假手术、对照组、APC （100 μ g/kg，静脉注射）、丹酰谷氨酰酰甘氨酸精氨酸氯甲基酮处理的活化因子X (DEGR-F) 6个实验组中，测定髓过氧化物酶和细胞因子（肿瘤坏死因子α (tnf - α)和白细胞介素-8）的组织水平。Xa)，选择性凝血酶生成抑制剂（1mg /kg，静脉注射），氮芥诱导的白细胞减少症，以及氟磷酸二异丙基处理的APC (DIP-APC)，活性位点阻断APC （100 μ g/kg，静脉注射）。APC, DEGR-F。在主动脉闭塞前30分钟静脉给予Xa和DIP-APC。对照组大鼠和白细胞减少大鼠用生理盐水代替其他药物。结果与对照组相比，APC预处理显著减轻了运动障碍。相比之下，DEGR-F。Xa和DIP-APC均无影响。在给予APC的动物中，没有TTC染色和组织学改变的微梗死明显减少。在接受APC的动物中，脊髓缺血部分组织中tnf - α、大鼠白细胞介素-8和髓过氧化物酶水平的升高明显降低。在给予DEGR-F的大鼠中，这些水平没有降低。Xa或DIP-APC，白细胞减少产生的效果与APC相似。结论sapc通过抑制中性粒细胞活化来减轻缺血再灌注所致脊髓损伤。APC的治疗机制可能取决于其对tnf - α产生的抑制作用，tnf - α是一种有效的中性粒细胞激活剂。尽管APC的抗凝作用可能与其抑制tnf - α产生的能力无关，但其丝氨酸蛋白酶活性似乎在治疗机制中至关重要。APC似乎有潜力作为一种治疗药物预防脊髓损伤的患者接受主动脉瘤修复。
ObjectiveTo examine whether activated protein C (APC) reduces spinal cord injury in rats by inhibiting neutrophil activation after the transient ischemia.Summary Background DataIschemic spinal cord injury is an important pathologic mechanism leading to the paraplegia observed after surgery to repair aortic aneurysms. Activated neutrophils play a pivotal role in the development of ischemia/reperfusion-induced tissue injury. Recently, the authors have reported that APC, a physiologic anticoagulant, prevents lipopolysaccharide-induced pulmonary vascular injury by inhibiting neutrophil activation. These observations strongly suggest that APC reduces ischemia/reperfusion-induced spinal cord injury by inhibiting neutrophil activation.MethodsIn rats, spinal cord ischemia was induced by using a balloon catheter placed into the aorta. After the transient ischemia, survival and motor function were evaluated, and histologic examination of the spinal cord was performed by using both hematoxylin-and-eosin staining and 2,3,5,-triphenyltetrazolium chloride (TTC) staining 24 hours after the ischemia. Tissue levels of myeloperoxidase and cytokines, including tumor necrosis factor-alpha (TNF-alpha) and rat interleukin-8, were measured in six experimental groups: sham-operated, control, APC (100 mu g/kg, intravenous), dansyl glutamyl-glycyl-arginyl chloromethyl ketone-treated activated factor X (DEGR-F.Xa), a selective inhibitor of thrombin generation (1 mg/kg, intravenous), nitrogen mustard-induced leukocytopenia, and diisopropyl fluorophosphate-treated APC (DIP-APC), active site-blocked APC (100 mu g/kg, intravenous). APC, DEGR-F.Xa, and DIP-APC were administered intravenously 30 minutes before aortic occlusion. Control and leukocytopenic rats received saline instead of other drugs.ResultsPretreatment with APC significantly reduced motor disturbances compared with those in control animals. In contrast, neither DEGR-F.Xa nor DIP-APC had any effect. Microinfarctions, evidenced by the absence of TTC staining and histologic change, were markedly reduced in animals given APC. The increases in the tissue levels of TNF-alpha, rat interleukin-8, and myeloperoxidase in the ischemic part of the spinal cord were significantly reduced in animals that received APC. These levels were not reduced in rats given DEGR-F.Xa or DIP-APC, Leukocytopenia produced effects similar to those of APC.ConclusionsAPC reduced the ischemia/reperfusion-induced spinal cord injury by inhibiting neutrophil activation. The therapeutic mechanisms of APC might depend on its inhibitory effect on the production of TNF-alpha, which is a potent activator of neutrophils. Although the anticoagulant effects of APC might not be related to its ability to inhibit TNF-alpha production, its serine protease activity appears to be essential in the therapeutic mechanism. APC appears to have potential as a therapeutic agent for prevention of spinal cord injury in patients undergoing aortic aneurysm repair.