Camp T M, Tyagi S C, Senior R M, Hayden M R, Tyagi S C
Department of Physiology and Biophysics, University of Louisville, 500 South Preston Street, Louisville, KY 40292, USA.
Diabetologia. 2003 Oct;46(10):1438-45. doi: 10.1007/s00125-003-1200-y. Epub 2003 Aug 20.
AIMS/HYPOTHESIS: Although matrix metalloproteinase-9 (MMP-9) is specifically induced and apoptosis of endothelial cells is evidenced in diabetes mellitus, the mechanism of endocardial endothelial dysfunction in diabetes mellitus is not clear. The increase in MMP-9 activity is associated with endocardial endothelial apoptosis and dysfunction in diabetes mellitus.
Diabetes was created by injecting 65 mg/kg alloxan in tail vein of MMP-9 knockout (-/-) and wild-type (WT, C57BL/J6) mice. At 8 weeks mice were grouped: (i) WT+saline; (ii) WT+alloxan; (iii) MMP+saline; (iv) MMP+alloxan. The MMP-9 genotype was determined by observing single PCR product of different mobility than the PCR product from wild-type in blood from tail vein.
MMP-9 activity, measured by zymography, increased in plasma and in the left ventricle of alloxan-induced diabetic wild-type mice. The concentrations of cardiac inhibitor of metalloproteinase, that blocks MMP-9 activity, were decreased in diabetic MMP-9 knockouts as well as in wild-type mice. Diabetes induced apoptosis, detected by TUNEL assays, in wild-type but not in MMP-9 knockouts. Endocardial endothelial function was severely impaired in diabetic wild-type mice compared with normoglycaemic animals, while non-diabetic MMP-9 knockout mice showed partial endocardial endothelial dysfunction which was not further exacerbated by the developments of diabetes.
CONCLUSION/INTERPRETATION: The results suggest an association between increased MMP-9 activity and endocardial endothelial apoptosis in diabetic mice, while genetic ablation of MMP-9 correlated with amelioration of endocardial endothelial dysfunction and apoptosis.
目的/假设：尽管基质金属蛋白酶-9（MMP-9）在糖尿病中被特异性诱导且内皮细胞凋亡得到证实，但糖尿病中心内膜内皮功能障碍的机制尚不清楚。MMP-9活性增加与糖尿病中心内膜内皮细胞凋亡和功能障碍有关。
通过向MMP-9基因敲除（-/-）和野生型（WT，C57BL/J6）小鼠尾静脉注射65mg/kg四氧嘧啶来诱导糖尿病。8周时将小鼠分组：（i）野生型+生理盐水；（ii）野生型+四氧嘧啶；（iii）MMP基因敲除+生理盐水；（iv）MMP基因敲除+四氧嘧啶。通过观察尾静脉血中与野生型PCR产物迁移率不同的单一PCR产物来确定MMP-9基因型。
通过酶谱法测定，四氧嘧啶诱导的糖尿病野生型小鼠血浆和左心室中MMP-9活性增加。在糖尿病MMP-9基因敲除小鼠和野生型小鼠中，抑制MMP-9活性的心脏金属蛋白酶抑制剂浓度均降低。通过TUNEL检测发现，糖尿病诱导野生型小鼠发生凋亡，但MMP-9基因敲除小鼠未发生凋亡。与血糖正常的动物相比，糖尿病野生型小鼠的心内膜内皮功能严重受损，而非糖尿病MMP-9基因敲除小鼠表现出部分心内膜内皮功能障碍，糖尿病的发展并未使其进一步加重。
结论/解读：结果表明糖尿病小鼠中MMP-9活性增加与心内膜内皮细胞凋亡之间存在关联，而MMP-9基因缺失与心内膜内皮功能障碍和凋亡的改善相关。
