MMP-2/TIMP-2比值与2型糖尿病大鼠心肌胶原代谢的关系及瑞舒伐他汀对其的干预

Relationship between MMP-2/TIMP-2 ratio and collagen metabolism in type 2 diabetic rats and rosuvastatin intervention

目的探讨基质金属蛋白酶-2(matrix metalloproteinases-2,MMP-2)/基质金属蛋白酶组织抑制剂-2(tissueinhibitor of matrix metalloproteinases-2,TIMP-2)与2型糖尿病大鼠心肌间质中胶原代谢的关系,及瑞舒伐他汀防治心肌间质纤维化的可能机制。方法30只雄性SD大鼠按随机数字表法抽取8只作为正常对照组,其余22只喂高脂,高糖饲料,并予低剂量链脲佐菌素单次腹腔注射。16只成模的糖尿病组大鼠按随机数字表法分成糖尿病组(n=8)与瑞舒伐他汀治疗组(n=8)。待血糖稳定后,治疗组开始给予瑞舒伐他汀干预处理,干预两个月后,处死大鼠,测定动物体质量,心脏质量,以计算心脏质量指数:心脏质量(g)/动物体质量(g)。酶联免疫吸附试验(ELISA)法分别测定3组大鼠血浆MMP-2、TIMP-2浓度,采用免疫组化方法检测心肌MMP-2、TIMP-2蛋白表达的水平和组织定位,采用Masson染色方法观察心肌间质胶原蛋白含量变化及分布。结果糖尿病组及治疗组血糖高于正常组,差异有统计学意义(P<0.05)。糖尿病组心脏质量指数高于治疗组和正常组,差异有统计学意义(P<0.05)。糖尿病组血浆MMP-2及TIMP-2浓度均比正常组高,差异有统计学意义(P<0.05)。治疗组血浆MMP-2及TIMP-2浓度比糖尿病组降低,差异有统计学意义(P<0.05)。然而,免疫组化检测到MMP-2在糖尿病组心肌间质中表达比正常组明显减少,在治疗组的表达比在糖尿病组增多,差异有统计学意义(P<0.05);TIMP-2在糖尿病组心肌间质中表达比正常组明显增多,在治疗组的表达比在糖尿病组减少,差异有统计学意义(P<0.05)。糖尿病组与正常组比较,MMP-2/TIMP-2比值下降;治疗组与糖尿病组比较,MMP-2/TIMP-2比值上升。心肌Masson染色:亮绿色纤维在糖尿病组心肌间质中明显比正常组增多,而治疗组比糖尿病组有所减少。结论糖尿病大鼠中MMP-2/TIMP-2比值下降可能是导致心肌间质纤维化的原因之一。瑞舒伐他汀可减轻糖尿病大鼠心肌间质的胶原沉积,其可能是通过升高MMP-2/TIMP-2比值,使糖尿病心肌间质纤维化有所减轻。

Objectives To investigate the relationship between matrix metalloproteinases-2 （MMP-2） / tissue inhibitor of matrix metalloproteinases-2 （TIMP-2） ratio and interstitial myocardial collagen metabolism in type 2 diabetic rats, and to discuss possible mechanism of rosuvastatin in preventing myocardial interstitial fibrosis. Methods Eight rats were randomly selected as normal control group from 30 male SD rats. The other 22 rats were fed with a high-fat, high- sugar diet, and given intraperitoneal injection of a single low-dose streptozotoein. Sixteen rats became mold of diabetic group. They were randomly divided into diabetic group （n=8） and rosuvastatin treatment group （n=8）. After blood sugar was stabilized, treatment group started to receive rosuvastatin treatment. Rats were sacrificed after 2 months of intervention. Their body weight ＇（BW） and heart weight （HW） were measured in order to determine their cardiac mass index： HW （g）/BW （g） ratio. Plasma levels of MMP-2, TIMP-2 in the three groups were measured by enzyme linked immunosorbent assay （ELISA） technique. Levels of myocardial protein expression of MMP-2 and TIMP-2 were determined by immunohistochemical method. With the aid of the masson stain, changes, tissue localization and distribution ofmyocardial collagen protein content were observed. Results Compared to control group, blood sugar concentrations of diabetic group and treatment group were significantly higher （P〈0.05）. Cardiac mass index of diabetic group was significantly higher than those of control group and treatment group （P〈0.05）. Plasma levels of MMP-2 and TIMP-2 in diabetic group were obviously higher than those in control group （P〈0.05）. Plasma levels of MMP-2 and TIMP-2 in treatment group were significantly lower than those in diabetic group（P〈0.05）. However, by using immunohistoehemical method, interstitial myocardial MMP-2 expression obviously decreased in diabetic group compared with control group and significantly increased in treatment group compared with diabetic group （P〈0,05）, Interstitial myocardial TIMP-2 expression significantly increased in diabetic group compared with control group and obviously decreased in treatment group compared with diabetic group （P〈O.O5）. MMP-2/TIMP-2 ratio decreased in diabetic group compared with control group. MMP-2/TIMP-2 ratio increased in treatment group compared with diabetic group. Myocardial masson staining： bright green appeared in myocardial interstitial fibrosis significantly increased in diabetic group compared with control group, but reduced in treatment group when compared with diabetic group. Conclusions MMP-2/TIMP-2 ratio imbalance may be one of the reasons of myocardial interstitial fibrosis in diabetic eardiomyopathy. Rosuvastatin can reduce collagen deposition in myocardial interstitium in diabetic rats by improving MMP-2/TIMP-2 balance, thus can ameliorate myocardial interstitial fibrosis.