Dynamic changes in myocardial matrix metalloproteinase activity in mice with viral myocarditis / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Matrix metalloproteinases (MMPs) are the major regulators of collagen degradation involved in the pathogenesis of several diseases of the heart. The purpose of this study was to investigate the dynamic changes in myocardial MMP activity in mice with viral myocarditis (VM), the relationship between MMP activity and both cardiac function and the quantity of myocardial collagen, and the role MMPs playing in the pathological lesions of VM.</p><p><b>METHODS</b>Sixty-five six-week-old male DBA/2 mice were divided into two groups. Mice in the 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 medium. Eight infected mice and three control mice were sacrificed on each of days 3, 7, 10, 21 and 30 after inoculation. MMP activity was measured on an SDS-PAGE substrate gel embedded with type I gelatin (zymography). Echocardiographic studies were performed under anesthesia with 3% chloralhydrate administered intraperitoneally (0.01 ml/g - 0.015 ml/g). Cardiac systolic function indices, such as peak velocity of the aorta (Vp), flow velocity integral of the aorta (Vi), ejection fraction (EF), and fractional shortening (FS) were determined by echocardiography. Histological cross sections of the hearts were stained with hematoxylin-eosin and myocardial histopathological scores were determined under an optical microscope. The amount of myocardial collagen was measured by means of hydroxyproline quantification.</p><p><b>RESULTS</b>In virus-infected mice, both MMP-2 and MMP-9 activities were significantly higher than in control mice, reaching a peak on day 10 (P < 0.01). On day 10, cardiac systolic function indices (EF, FS, Vp, and Vi) were all significantly lower compared both to other stages following viral inoculation and to the control group (P < 0.05). In the acute stage, the amount of myocardial collagen in mice with VM was not significantly different from normal control mice (P > 0.05). However, the amount of myocardial collagen in infected mice at the recovery stage (on days 21 and 30) was significantly greater than those of the control mice. MMP-2 and MMP-9 activities positively correlated with myocardial histopathological scores (r = 0.801, 0.821, P < 0.01) and negatively correlated with Vp (r = -0.649, -0.683, P < 0.01) and Vi (r = -0.711, -0.755, P < 0.01). However, Vp negatively correlated with myocardial histopathological scores (r = -0.756, P < 0.01).</p><p><b>CONCLUSIONS</b>In mice with VM, the activities of myocardial MMP-2 and MMP-9 increase significantly during the acute stage, and the total quantity of myocardial collagen increases by the time of recovery. These changes are associated with myocardial interstition remodeling and cardiac dysfunction. MMP activity is an important reference marker for myocardial pathological lesions and can be used to evaluate the severity of myocardial interstitial damage and cardiac dysfunction.</p>

Myocardial matrix metalloproteinases activities in mice with viral myocarditis and their relationship with cardiac function and myocardial collagen amount / 中华儿科杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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).</p><p><b>CONCLUSIONS</b>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.</p>

Effects of Intravenous Immunoglobulin on Apoptosis and Necrosis of Myocytes in Viral Myocarditis / 实用儿科临床杂志

Objective To investigate the effects of intravenous immunoglobulin(IVIG) on apoptosis and necrosis of myocytes in mice with viral myocarditis.Methods Three hundreds and twenty Balb/c mice were randomly divided into 8 groups.Different courses of IVIG were given in varying time after virus inoculation,Chinese medicine Huangqi given in control group.The virus titer in myocardium、percentage of apoptosis and necrosis of myocytes were detected, myocardial histopathologic scores were counted.Results In every IVIG treatment group,the above 3 items were all significantly lower than that in virus control group and Huangqi group,as IVIG early long course group had the best effect.Conclusion IVIG may reduce the percentage of apoptosis and necrosis of myocytes and virus titer in myocardium in mice with viral myocarditis,the effects are better than that of Huangqi.