病毒性心肌炎心肌基质金属蛋白酶活性的动态变化及其与心功能和心肌胶原的关系

目的 探讨病毒性心肌炎(viral myocarditis,VM)心肌基质金属蛋白酶(matrixmetalloproteinases,MMPs)活性的动态变化及其与心功能、心肌胶原的关系。方法 50只6周龄雄性DBA/2小鼠腹腔接种0.14 ml的CVB3建立VM模型,15只同周龄同品系小鼠腹腔接种0.14 ml的Eagle's液作为对照组。VM组于接种后3、7、10、21、30 d,对照组于30 d均采用酶谱法测定心肌基质金属蛋白酶2(MMP-2)和9(MMP-9)的活性;超声心动图测定心脏收缩功能:主动脉血流峰值流速(Vp)、主动脉血流速度积分(Vi);心脏石蜡切片HE染色计算病理积分以及氯氨T法测定心肌的胶原含量。结果 VM小鼠心肌MMP-2、MMP-9的活性表现为一过性增高,以10 d时为最高,并且10 d时Vp、Vi亦明显低于对照组(P<0.05);心肌胶原含量在21 d、30 d时显著增高(P<0.05);MMP-2、MMP-9与病理积分均呈正相关(r分别为0.801,0.821,均P<0.05)、与Vp、Vi呈负相关(r分别为-0.649,-0.683和-0.711,-0.755,均P<0.05)。结论 VM小鼠心肌MMPs过度激活并伴有继发的胶原含量升高,且MMPs活性与心肌病理损害、心功能下降密切相关。MMPs参与了心肌炎的病理改变,可能是导致间质改变、心功能异常的因素之一,提示心肌MMPs是VM心脏间质病变的关联因素,可用来作为判断VM小鼠心肌间质损害程度及估计心脏功能的

Myocardial matrix metalloproteinases activities in mice with viral myocarditis and their relationship with cardiac function and myocardial collagen amount

OBJECTIVE: To investigate the dynamic changes of myocardial matrix metalloproteinases (MMPs) activities in mice with viral myocarditis (VM) and their relationships with cardiac function and myocardial collagen amount and to explore the role of MMPs in the pathologic lesion of VM. METHODS: Sixty-five six-week-old male DBA/2 mice were obtained from the Chinese Academy of Medical Sciences. They were divided into two groups randomly. Mice in infected group (n=50) were inoculated intraperitoneally with 0.14 ml of coxsackievirus B3 (CVB3, Nancy strain). Control mice (n=15) were inoculated intraperitoneally with 0.14 ml of Eagle's solution. Eight infected mice were sacrificed on day 3, 7, 10, 21 and 30, respectively and fifteen control mice were killed on day 30 after inoculation. Total protein concentration was determined according to the method of Bradford, while MMPs activities were measured with SDS-PAGE type substrate gels embedded with type I gelatin (zymography). Echocardiographic studies were performed under anesthesia with 3% chloralhydrate intraperitoneally (0.01-0.015 ml/g). Cardiac systolic function indexes, such as peak velocity of aorta (Vp) and flow velocity integral of aorta (Vi) were determined by echocardiography. Histological cross sections of hearts were stained with hematoxylin-eosin and myocardial histopathologic scores were counted under optical microscope. Myocardial collagen amount was measured by determination of hydroxyproline quantification. RESULTS: In virus-infected mice, both MMP-2 and MMP-9 activities were increased significantly compared with those in controls and reached the peak on day 10 (P < 0.01). On day 10, cardiac systolic function indexes (Vp and Vi) were all significantly lower than those at other stages after virus inoculation and in control group (P < 0.05). There was no obvious elevation in myocardial collagen amount in mice with VM at acute stage (P > 0.05). While the myocardial collagen amount in infected group at recovery stage (on day 21 and 30) increased significantly compared with controls. MMP-2 and MMP-9 activities positively correlated with myocardial histopathological scores, respectively (r =0.801, 0.821 P < 0.01), while they negatively correlated with Vp (r = -0.649, -0.683, P < 0.01) and Vi, respectively (r = -0.711, -0.755, P < 0.01). However, Vp and Vi negatively correlated with myocardial histopathological scores (r = -0.756, -0.584, P < 0.01). CONCLUSIONS: In mice with VM, the activities of myocardial MMP-2 and MMP-9 at acute stage increased significantly, then myocardial collagen amount elevated in recovery stage. These changes were associated with myocardial remodeling and cardiac dysfunction. Myocardial MMP activities are important markers of myocardial pathologic lesion. They are of value in the evaluation of the severity of myocardial damage and cardiac dysfunction in mice with VM.