血管损伤修复与基质金属蛋白酶

背景：基质金属蛋白酶是一组能特异降解细胞外基质成分依赖锌的酶家族,近年来研究发现其参与了血管损伤后早期应激反应,与血管损伤后再狭窄发生相关。目的：就基质金属蛋白酶在血管损伤中的一些生理病理过程做一综述。方法：应用计算机检索Medline数据库、Ovid数据库、Springerlink数据库、维普数据库及中国知网数据库,纳入1990/2010发表的29篇基质金属蛋白酶与血管损伤以及药物等干预有关的文献进行总结分析。结果与结论：心血管动脉系统在损伤后,包括经皮腔内血管成形后血管狭窄的发生率较高。基质金属蛋白酶在受损动脉的局部表达增加,通过促进内膜增厚和改变血管重构而促进血管损伤后再狭窄的发生。因此,降低血管受损局部基质金属蛋白酶表达将成为防治血管内再狭窄的一个方向。关键词：血管损伤;血管内再狭窄;基质金属蛋白酶;基质金属蛋白酶组织抑制因子;血管组织工程     

川芎嗪对肝星状细胞基质金属蛋白酶13和金属蛋白酶组织抑制剂1

背景：既往动物实验表明,川芎嗪能降低肝纤维化大鼠血清Ⅲ型胶原、透明质酸及层粘连蛋白水平,延缓肝纤维化的形成,但其具体作用机制尚不清楚。目的：观察川芎嗪对肝星状细胞增殖及基质金属蛋白酶13和基质金属蛋白酶组织抑制因子1 mRNA表达的影响,并探讨川芎嗪抗肝纤维化的可能机制。设计、时间及地点：观察性实验,于2006-11/2007-06在重庆医科大学基础医学研究所完成。材料：盐酸川芎嗪注射液(10 mL∶80 mg),使用时用含体积分数为0.1小牛血清的1640培养基稀释,为巴里莫尔制药(通化)有限公司产品;肝星状细胞株HSC-T6,系SV40转染SD大鼠肝星状细胞而成,其表型为活化的肝星状细胞,由中国医学科学院肿瘤研究所提供。方法：培养肝星状细胞株,传至三四代时增殖明显即可用于实验。实验分为2组,空白对照组：仅加入细胞;药物干预组：分别加入川芎嗪0.01,0.1,1,10,50,100,200,400,600,1 000 mg/L后作用于HSC-T6。主要观察指标：四甲基偶氮唑盐比色法测定肝星状细胞增殖;ELISA法检测Ⅰ、Ⅲ型胶原及透明质酸质量浓度;反转录-聚合酶链反应检测基质金属蛋白酶13和基质金属蛋白酶13 mRNA的表达。结果：①与空白对照组相比,川芎嗪100~1 000 mg/L各剂量组作用不同时间的吸光度值均降低(P < 0.01)。在川芎嗪100~1 000 mg/L 这一质量浓度范围内,随着药物质量浓度加大,对细胞的抑制作用增加。②川芎嗪(100,200 mg/L)对Ⅰ、Ⅲ型胶原、透明质酸的产生有抑制作用(P < 0.05~0.01),并随着药物质量浓度增加,抑制作用增强。10 mg/L川芎嗪对Ⅰ、Ⅲ型胶原均没有影响,但可以降低透明质酸质量浓度(P < 0.05)。③100,200 mg/L川芎嗪可促进基质金属蛋白酶13的表达,随药物质量浓度增大,基质金属蛋白酶13/基质金属蛋白酶组织抑制因子1比值增大(P < 0.05~0.01)。结论：川芎嗪抗纤维化的可能机制是抑制肝星状细胞的增殖;促进基质金属蛋白酶13的表达,从而促进胶原降解,使细胞外基质减少。     

大鼠胸主动脉损伤后基质金属蛋白酶组织抑制因子1，2的表达与血管内膜增生

背景：已有研究发现,基质金属蛋白酶及其组织特异性抑制因子通过影响血管平滑肌细胞迁移以及细胞外基质的代谢参与再狭窄过程。 目的：观察基质金属蛋白酶组织抑制因子1,2在大鼠胸主动脉损伤后不同时间的表达情况。 设计、时间及地点：随机对照动物实验,于2008-07在辽宁医学院动物实验中心完成。 材料：选用SD雄性大鼠60只,按随机数字表法分为2组,单纯球囊损伤组及对照组各30只。 方法：单纯球囊损伤组大鼠采用2F Fogarty导管损伤胸主动脉;对照组行左颈总动脉结扎术,不插入2F Fogarty导管。 主要观察指标：2组于术后第1,3,7,10,14,28天分别处死5只大鼠,取完整的血管内膜,应用蛋白印迹法检测动脉损伤后不同时间点基质金属蛋白酶组织抑制因子1,2表达水平,并进行比较。 结果：基质金属蛋白酶组织抑制因子1于大鼠动脉损伤后第1天开始表达增加,第7天达到高峰,第28天几乎无表达。基质金属蛋白酶组织抑制因子2于大鼠动脉损伤后第1,3天仅有较弱的表达,第7,10天表达明显增加,第14天达到高峰,第28天仍有较强表达。对照组中各时间点基质金属蛋白酶组织抑制因子1,2的表达均无明显变化(P > 0.01)。术后各时间点基质金属蛋白酶组织抑制因子1,2的表达水平单纯球囊损伤组均显著高于对照组(P < 0.01)。 结论：大鼠胸主动脉球囊损伤后基质金属蛋白酶组织抑制因子1,2的表达均明显增加。 关键词：基质金属蛋白酶组织抑制因子1,2;动脉损伤;再狭窄     

川芎嗪对兔颈动脉球囊损伤后内膜增生的影响

目的研究川芎嗪对兔颈动脉球囊损伤后新生内膜及管腔狭窄度的影响，探讨其预防再狭窄的可能性。方法应用直径为3mm的球囊导管造成家兔左颈动脉去内皮损伤模型。术后14d和28d分别测量对照组和川芎嗪治疗组动脉新生内膜及中膜厚度、新生内膜面积和管腔狭窄度并应用Brdu和α-actin免疫组化方法观察新生内膜细胞的增殖指数。结果治疗组新生内膜及中膜厚度、新生内膜面积．管腔狭窄度和细胞增殖指数均明显低于对照组。结论川芎嗪具有明显抑制动脉损伤后新内膜的形成及降低管腔狭窄度的作用。     

烟雾病患者血清基质金属蛋白酶-9和组织基质金属蛋白酶抑制剂-1的表达以及与颅内出血的关系

目的 探讨烟雾病(MMD)患者血清基质金属蛋白酶-9(MMP-9)和组织基质金属蛋白酶抑制剂-1(TIMP-1)的表达以及与颅内出血的关系.方法 检测26例有颅内出血的MMD的患者(出血组)、21例无出血的MMD患者(无出血组)及25名健康对照者(正常对照组)的血清MMP-9、TIMP-1水平,并进行比较.结果 与正常对照组比较,出血组与无出血组患者血清MMP-9及TIMP-1水平显著升高(均P＜0.01).与无出血组比较,出血组MMP-9/TIMP-1显著增高(P＜0.05),MMP-9与TIMP-1水平差异无统计学意义.出血组及无出血组血清TIMP-1与MMP-9水平均呈正相关(r=0.626,r=0.645;均P＜0.01).结论 MMP-9及TIMP-1在MMD患者血清中表达显著升高.MMP-9与TIMP-1比例失衡可能是引起MMD患者颅内出血的重要机制.     

依达拉奉对脑梗死患者血清基质金属蛋白酶-9及基质金属蛋白酶抑制剂-1的影响

目的探讨依达拉奉对急性脑梗死患者血清基质金属蛋白酶-9(MMP-9)及基质金属蛋白酶抑制剂-1(TIMP-1)的影响并探讨其作用机制。方法40例急性脑梗死患者随机分成两组,A组(银杏达莫20ml,1次/d,连续14d,静脉点滴);B组(加用依达拉奉注射液30mg,2次/d,连续14d,静脉点滴)。同期选择非脑血管病患者20例作为对照组。检测治疗前和治疗后第7天患者血清MMP-9及TIMP-1浓度的变化,测定治疗前、治疗第30天的NIHSS评分,判定两组的疗效。结果在治疗第7天,B组的MMP-9浓度明显低于A组(P<0.01)。治疗第7天时,与A组相比,B组TIMP-1浓度升高明显(P<0.01)。B组治疗的有效率及显效率明显高于A组(P<0.05)。结论依达拉奉能够直接降低血清MMP-9的浓度,或通过调节TIMP-1来降低MMP-9水平,可能是其有效治疗急性脑梗死的机制之一。     

基质金属蛋白酶组织抑制剂-1、2的表达与慢性酒精中毒性肌病的相关性研究

目的研究TIMP-1和TIMP-2的表达与慢性酒精中毒性肌病的相关性。方法通过RT—PCR和Western blotting方法,检测正常大鼠和慢性酒精中毒性大鼠骨骼肌中TIMP-1和TIMP-2的表达差异。结果慢性酒精中毒性大鼠骨骼肌TIMP-1的表达水平增高,腓肠肌更为明显。TIMP-2的表达无显著性差异。结论TIMP-1的增高可能参与了骨骼肌间质纤维增生及其构成的改变,诱导炎性细胞浸润,加重慢性酒精中毒性肌病的发生发展。TIMP-2可能不参与骨骼肌阎质纤维的增生及其构成的改变。     

基质金属蛋白酶-9及组织基质金属蛋白酶抑制剂-1在脑动静脉畸形血清中的表达及与出血的关系

目的 研究基质金属蛋白酶-9（matrix metalloproteinase-9,MMP-9）及组织基质金属蛋白酶抑制剂-1（tissue inhibitor of metalioproteinases-1,TIMP-1）在脑动静脉畸形（cerebullar arteriovenous malformations,CAVM）患者血清中的表达及其与出血的关系。 方法 选取48例脑动静脉畸形患者。按有无出血症状分为出血组及非出血组,并选取24例原发癫患者为正常对照组。对患者术前及术后3d、7d血清中的MMP-9和TIMP-1水平进行研究。 结果 术前出血组及非出血组中,MMP-9、TIMP-1含量均显著高于对照组（P<0.01）,术后出血组及非出血组中,上述指标与术前相比有所下降,但仍高于同期对照组（P<0.01）。出血组及非出血组间,术前与术后MMP-9、TIMP-1含量均无统计学差异（P>0.05）,但术前两组间MMP-9与TIMP-1之比值（MMP-9/TIMP-1）具有统计学差异（P<0.05）。 结论 MMP-9及TIMP-1与CAVM的发生发展有密切关系,MMP-9水平升高可能是TIMP-1合成和分泌的促进因素之一。MMP-9和TIMP-1比例失衡,可能是引起脑动静脉畸形出血的重要机制。     

脑出血大鼠血肿周围脑组织含水量与基质金属蛋白酶-9、组织基质金属蛋白酶抑制剂-1及谷氨酸表达水平的关系

目的 探讨脑出血大鼠血肿周围脑组织含水量与基质金属蛋白酶-9(MMP-9)、组织基质金属蛋白酶抑制剂-1(TIMP-1)及谷氨酸表达水平的关系.方法 雄性Wistar大鼠48只,随机分为正常对照组(n=8)、假手术组(n=8)、脑出血组(n=32),脑出血组又分为脑出血后12h、24h、72 h、7d4个亚组,每亚组8只大鼠.采用自体血尾状核注入法制备脑出血模型.采用干湿重法测定脑含水量,免疫组化法检测血肿周围脑组织MMP-9、TIMP-1及谷氨酸的表达.结果 脑出血组各时间点亚组大鼠血肿周围脑组织含水量与MMP-9、TIMP-1及谷氨酸表达水平均显著高于正常对照组和假手术组(均P＜0.01).脑出血组中,72 h亚组大鼠脑组织含水量及MMP-9、TIMP-1表达水平最高(P ＜0.01);24 h亚组大鼠脑组织谷氨酸表达水平最高(P＜0.01).多重线性回归分析结果显示,脑组织含水量(Y)与脑组织MMP-9(X1)及谷氨酸(X3)表达水平呈直线关系,多元回归方程为Y=68.894+0.281X1-0.052X3.结论 脑出血后血肿周围组织含水量及MMP-9、TIMP-1、谷氨酸的表达水平明显增高,MMP-9、谷氨酸在脑出血后血肿周围组织水肿的发生发展中具有重要作用.     

中青年脑梗死患者颈动脉粥样硬化及其血清基质金属蛋白酶-9、组织基质金属蛋白酶抑制剂-1、超敏C反应蛋白水平的改变

目的研究中青年脑梗死患者颈动脉粥样硬化及其血清基质金属蛋白酶-9(MMP-9)、组织基质金属蛋白酶抑制剂-1(TIMP-1)、超敏C反应蛋白(hs-CRP)水平的改变。方法应用彩色多普勒超声仪探测42例急性脑梗死患者(ACI组)、29例无症状颈动脉硬化患者(ACA组)及17名健康体检者(NC组)的双侧颈动脉粥样硬化的情况。采用酶联免疫吸附法检测各组血清MMP-9和TIMP-1水平,免疫散射比浊法检测血清hs-CRP水平。结果 NC组均未检出颈动脉粥样硬化斑块。ACI组易损斑块的比例(69.2%)及检出率(47.6%)均明显高于ACA组(46.4%,20.7%)(均P<0.05)。ACI组血清MMP-9、TIMP-1、hs-CRP水平及MMP-9/TIMP-1比值均明显高于ACA组(均P<0.05);ACA组血清MMP-9、TIMP-1、hs-CRP水平均明显高于NC组(均P<0.05)。ACI组中,易损斑块亚组血清MMP-9、TIMP-1、hs-CRP水平及MMP-9/TIMP-1比值均明显高于稳定斑块亚组(均P<0.05);稳定斑块亚组血清MMP-9、TIMP-1、hs-CRP水平均明显高于无斑块亚组(均P<0.05)。结论血清MMP-9、TIMP-1、hs-CRP可作为反映颈动脉粥样硬化及斑块稳定性的血清学指标。MMP-9/TIMP-1比值增高及颈动脉易损斑块可能提示中青年脑梗死的风险。     

Expressions of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 in malignant peripheral nerve sheath tumor

BACKGROUND: Matrix metalloproteinase-9 (MMP-9) can degrade collagen Ⅳ (the main structural ingredient of basilar membrane), and it also plays an important role in tumor vascularization, tumor cell progression, formation of metastatic focus, etc. Tissue inhibitor of metalloproteinase-1 (TIMP-1) can bind with MMP-9 to form 1∶1 compound and inhibit its activity, and can negatively regulate the tumor progression and metastasis. OBJECTIVE: To analyze the relationship of MMP-9 and TIMP-1 expressions with the pathological grade, metastasis and prognosis of malignant peripheral nerve sheath tumor (MPNST). DESIGN: An observational comparative experiment. SETTING: Heze Medical College. PARTICIPANTS: Fifty-eight surgical pathological samples, which were clearly diagnosed to be MPNST, were collected from the pathological laboratory archives in the Department of Pathology, Heze Municipal Hospital from January 1988 to December 2003. The MPNST pathological types were common tumor in 53 cases, malignant triton tumor in 2 cases, epithelial MPNST in 2 cases and MPNST with gland differentiation in 1 case. The pathological grade was grade 1 in 11 cases, grade 2 in 24 cases and grade 3 in 23 cases. Besides, the resected tumor samples of 20 patients with benign peripheral nerve tumor (10 cases of nerve sheath tumor and 10 cases of neurofibromatosis) and the normal peripheral nerves (by-products of some surgeries) of 5 patients were also collected. The samples were used with the approval of the patients. Rat-anti-human MMP-9, TIMP-1 monoclonal antibody and S-P kit were purchased from Fuzhou Maixin Biotechnology, Co.,Ltd. METHODS: The documented paraffin blocks were again prepared to sections of 5 μm. The expressions of MMP-9 and TIMP-1 in the samples were detected with mmunohistochemical S-P method. The relationships of the MPNST severity, recurrence, metastasis and survival rate with the expressions of MMP-9 and TIMP-1 were analyzed. MAIN OUTCOME MEASURES: Relationships of MMP-9 and TIMP-1 expressions with the MPNST severity and prognosis. RESULTS: ① Expressions of MMP-9 and TIMP-1 in three tissues: MMP-9 and TIMP-1 stainings were mainly observed in cytoplasm. Among the 58 MPNST patients, the MMP-9 expression was significantly higher than those in normal peripheral nerve and benign tumor (P < 0.05), while the TIMP-1 expression in MPNST was lower than those in normal peripheral nerve and benign tumor (P < 0.05). ② Relationship of MMP-9 and TIMP-1 expressions with the severity and prognosis of MPNST: The expressions of both proteins were observed in the four subtypes. The positive expression of MMP-9 in the MPNST patients of grades 2–3 was significantly higher than that in the MPNST patients of grade 1 (P < 0.05), while the expression of MMP-9 was significantly lower than that in the MPNST patients of grade 1 (P < 0.05). The metastatic rate was positively correlated with MMP-9 expression (r =1.696, P < 0.05), but negatively correlated with TIMP-1 expression (r =–2.125, P < 0.05). CONCLUSION: MMP-9 and TIMP-1 are associated with MPNST pathological grades and metastasis, and can be used as the indicators for judging the severity and prognosis of MPNST.     

Matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 expression in early focal cerebral infarction following urokinase thrombolysis in rats

Activity of matrix metalloproteinase-9 increases following cerebral ischemia/reperfusion,and is associated with cerebral microvascular permeability,blood-brain barrier destruction,inflammatory cell infiltration and brain edema.Matrix metalloproteinase-9 also likely participates in thrombolysis.A rat model of middle cerebral artery infarction was established by injecting autologous blood clots into the internal carotid artery.At 3 hours following model induction,urokinase was injected into the caudal vein.Decreased neurological severity score,reduced infarct volume,and increased expression of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 were observed in the cerebral cortex 24 hours after urokinase thrombolysis.These results suggest that urokinase can suppress damage in the acute-early stage of cerebral infarction.     

Expression of tissue inhibitor of metalloproteinase-1 in progression muscular dystrophy

Objective Tissue inhibitor of metalloproteinase-1(TIMP-1) is a multifunctional protein that has the capacity to modify cellular activities and to modulate matrix turnover. This paper revealed the contributive role of TIMP-1 in progressive muscular dystrophy (PMD). Methods We examined the expression and cellular localization of TIMP-1 protein using biopsied frozen muscle from patients with Duchenne muscular dystrophy ( DMD) , Becker muscular dystrophy (BMD) , congenital muscular dystrophy (CMD) by immunohistochemistry, double immunofluorescence and Western blot analysis. Results The results of immunohistochemistry and double immunofluorescence showed that TIMP-1 was positive only in vascular endothelial cells of normal muscles. Immunohistochemistry and Western blot analysis showed that the staining intensity was distinctly increased in some dystrophic muscles of PMD for TIMP-1. Double immunofluorescence revealed that TIMP-1 strongly expressed in the regenerating muscle fibers, macrophages and macrophage infiltrating necrotic fibers. Some activated fibroblasts in endomysium and perimysium of DMD and CMD muscles were also positive for TIMP-1. Conclusion The functional consequence of overexpression of TIMP-1 in the dystrophic muscles is unknown, but the elevated local expression of TIMP-1 in diseased muscles of PMD and their distinct distribution pattern provide evidence that TIMP-1 may participate in the pathogenesis of PMD.     

Expression of tissue inhibitor of metalloproteinase-1 in progression muscular dystrophy

Objective Tissue inhibitor of metalloproteinase-1 （TIMP-1） is a muhifunctional protein that has thc capacity to modify cellular activities and to modulate matrix turnover. This paper revealed the contributive role of TIMP-1 in progressive muscular dystrophy （PMD）. Methods We examined the expression and cellular localization of TIMP-1 protein using biopsied frozen muscle from patients with Duchenne muscular dystrophy （DMD）, Becker muscular dystrophy （BMD） , congenital muscular dystrophy （CMD） by immunohistochemistry, double immunofluorescence and Western blot analysis. Results The results of immunohistochemistry and double immunofluorescence showed that TIMP-1 was positive only in vascular endothelial cells of normal muscles. Immunohistochemistry and Western blot analysis showed that the staining intensity was distinctly increased in some dystrophic muscles of PMD for TIMP-1. Double immunofluorescence revealed that TIMP-1 strongly expressed in the regenerating muscle fibers, macrophages and macrophage infiltrating necrotic fibers. Some activated fibroblasts in endomysium and perimysium of DMD and CMD muscles were also positive for TIMP- 1. Conclusion The functional consequence of overexpression of TIMP-1 in the dystrophic muscles is unknown, but the elevated local expression of TIMP-1 in diseased muscles of PMD and their distinct distribution pattern provide evidence that TIMP-1 may participate in the pathogenesis of PMD.     

Matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 in perinatal asphyxia

Matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) play important roles in the function of the blood–brain-barrier (BBB). We investigated the roles of MMP-9 and TIMP-1 in the pathogenesis of hypoxic–ischemic encephalopathy following perinatal asphyxia. Serum concentrations of MMP-9 and TIMP-1 were determined by ELISA in 12 neonates with perinatal asphyxia and 15 controls on the birth day and the next day. Serum MMP-9 concentrations in asphyxiated neonates with neurological sequelae (n = 5) were significantly higher than concentration in asphyxiated neonates without sequelae (n = 7) and controls on birth day (p = 0.003 and p < 0.001, respectively). The ratios of serum MMP-9/TIMP-1 on birth day in asphyxiated neonates with neurological sequelae were significantly higher than those in asphyxiated neonates without sequelae (p = 0.048). There were no significant differences in the serum MMP-9 concentrations or the ratios of MMP-9/TIMP-1 between asphyxiated neonates with and without neurological sequelae on the day after birth. Our preliminary study suggests that serum MMP-9 levels on birth day are important for predicting neurological prognosis of neonates with asphyxia.     

Serum matrix metallopeptidase-9 and tissue inhibitor of metalloproteinase-1 levels in autoimmune encephalitis

ObjectiveSome pediatric patients with autoimmune encephalitis (AE) experience sequelae in spite of immunotherapy. In this study, we aimed to evaluate the association of serum matrix metallopeptidase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) levels with the neurological prognosis of AE.MethodsWe retrospectively included 13 patients with AE who had been referred to Saitama Children’s Medical Center from February 2011 to May 2019. We compared serum MMP-9 levels, TIMP-1 levels, and MMP-9/TIMP-1 ratio in the acute period (within 30 days from the onset of AE) and subacute period (30-day period following the acute period). We also compared these biomarker levels between patients with (group A) and without sequelae (group B). Sequelae were evaluated at discharge or the last visit.ResultsGroup A (median age, 7.8 years; range, 5.3–10.7 years) and group B (median age, 13.3 years; range, 11.1–15.4 years) had 6 patients each; 1 patient was excluded because the time of AE onset was unknown. In the acute period, there were no significant differences in MMP-9 levels, TIMP-1 levels, and MMP-9/TIMP-1 ratio between groups A and B. In the subacute period, serum MMP-9/TIMP-1 ratio was higher in group A than in group B (p < 0.01). There were no significant differences in MMP-9 and TIMP-1 levels between groups A and B.ConclusionsPatients with sequelae of AE showed a high MMP-9/TIMP-1 ratio in the subacute period. Our study demonstrates that elevation of serum MMP-9/TIMP-1 ratio in the subacute period may be a predictive factor of sequelae of AE.     

Imbalance of matrix metalloproteinase-9 and matrix metalloproteinase tissue inhibitor-1 may contribute to hemorrhage in cerebellar arteriovenous malformations

In this study,we determined the expression levels of matrix metalloproteinase-2 and-9 and matrix metalloproteinase tissue inhibitor-1 and-2 in brain tissues and blood plasma of patients undergoing surgery for cerebellar arteriovenous malformations or primary epilepsy(control group).Immunohistochemistry and enzyme-linked immunosorbent assay revealed that the expression of matrix metalloproteinase-9 and matrix metalloproteinase tissue inhibitor-1 was significantly higher in patients with cerebellar arteriovenous malformations than in patients with primary epilepsy.The ratio of matrix metalloproteinase-9 to matrix metalloproteinase tissue inhibitor-1 was significantly higher in patients with hemorrhagic cerebellar arteriovenous malformations compared with those with non-hemorrhagic malformations.Matrix metalloproteinase-2 and matrix metalloproteinase tissue inhibitor-2 levels were not significantly changed.These findings indicate that an imbalance of matrix metalloproteinase-9 and matrix metalloproteinase tissue inhibitor-1,resulting in a relative overabundance of matrix metalloproteinase-9,might be the underlying mechanism of hemorrhage of cerebellar arteriovenous malformations.