Tubulointerstitial injury is exacerbated in streptozotocin-induced diabetic matrix metalloproteinase-2 knockout mice

背景和目标：基质金属蛋白酶-2（MMP-2）是一种高效的金属蛋白酶，可降解各种类型的细胞外基质（ECM），如胶原IV、V和层粘连蛋白。已经表明糖尿病诱导的ECM积累至少部分是通过MMP-2的下调。但MMP-2的活性和表达是否影响糖尿病肾损害的体内研究尚未见报道。材料与方法：采用链脲佐菌素（STZ）（50 mg/kg）诱导雄性MMP-2基因敲除小鼠（MMP-2 KO）和C57 BL/6 J小鼠（Ctrl）糖尿病模型，观察MMP-2基因敲除对糖尿病大鼠肾小管间质损伤的影响。16周后，分别用酶谱法和实时荧光PCR法测定皮质MMP-2的表达和活性。采用酶联免疫吸附试验（ELISA）测定尿白蛋白排泄量（UAE）和N-乙酰-β-D-氨基葡萄糖苷酶（NAG）。免疫印迹法和免疫组化法检测α-平滑肌肌动蛋白（α-SMA）的表达 ...更多信息 mistry。结果：与非糖尿病对照组小鼠相比，16周糖尿病小鼠的血糖和HbA 1c水平升高约2-3倍（血糖：490.3+/-7.5mg/dl，HbA 1c; 9.91+/-0.22%，16周糖尿病小鼠）。酶谱分析和RT-PCR分析显示糖尿病小鼠肾皮质MMP-2表达和活性增加。MMP-2敲除DM小鼠血清BUN、Cr和UAE水平显著高于对照DM小鼠（BUN ; 23.2+/-1.7 vs 39.8+/-6.0mg/dl，p<0.01，Cr ; 0.07+/-0.01 vs 0.17+/-0.04mg/dl，p<0.01，UAE ; 0.08+/-0.01 vs 0.16+/-0.03mg/mgCr，p<0.05）。此外，肾小管间质损伤和皮质α-SMA表达在DM小鼠中增强，在MMP-2 KO DM mice中进一步增加。结论：我们首次证明糖尿病MMP-2敲除小鼠中肾小管间质损伤和纤维化加剧，即使MMP-2水平在糖尿病小鼠中增加。本研究提示，其他基质降解酶的减少可能参与了糖尿病肾病肾小管间质损伤和纤维化。少

Background and Aims : Matrix metalloproteinnase-2 (MMP-2) is one of the potent metalloproteinases which can degrade various types of extracellular matrix (ECM) such as collagen IV, V and laminin. It has been suggested that diabetes-induced accumulation of ECM are, at least in part, by down-regulation of MMP-2. However there is no data whether MMP-2 activity and expression affect diabetes-induced renal damage in vivo. Therefore, we investigated the effects of MMP-2 deficiency on tubulointerstitial injury in diabetic animals.Materials and Methods : Diabetes was induced by streptozotocin (STZ)(50mg/kg) in male MMP-2 knockout mice (MMP-2 KO) and C57BL/6J mice (Ctrl). After 16 weeks, cortical MMP-2 expression and activity were measured by zymography and real-time PCR, respectively. Urinary albumin excretion (UAE) and N-acetyl-β-D-glucosaminidase (NAG) were measured by enzyme-linked immunosorbent assay (ELISA). Alfa-smooth muscle actin (α-SMA) was evaluated by western blots and immnohistoche … More mistry. Tubulointerstitial injury and fibrosis were evaluated by hematoxylin and eosin staining (HE) and Masson-trichrome staining, respectively.Results : Plasma levels of glucose and HbA1c were increased by about 2-3-folds in 16-week diabetic mice compared with non-diabetic Ctrl mice (plasma glucose ; 490.3+/-7.5mg/dl, HbA1c ; 9.91+/-0.22% in 16-week diabetic mice). MMP-2 expression and activity in the total kidney cortex of diabetic mice were increased in zymography and RT-PCR analysis. Serum levels of BUN, creatinine (Cr) and UAE were significantly increased in MMP-2 KO DM mice compared with Ctrl DM mice (BUN ; 23.2+/-1.7 vs 39.8+/-6.0mg/dl, p<0.01, Cr ; 0.07+/-0.01 vs 0.17+/-0.04mg/dl, p<0.01, UAE ; 0.08+/-0.01 vs 0.16+/-0.03mg/mgCr, p<0.05). Further, tubulointerstitial injury and cortical α-SMA expression were enhanced in DM mice, which were further increased in MMP-2 KO DM mice.Conclusions : We demonstrate for the first time that tubulointerstitial injury and fibrosis were exacerbated in diabetic MMP-2 knockout mice, even though MMP-2 levels were increased in diabetic mice. The present study suggests that the decrease in other matrix-degrading enzymes may be involved in the tubulointerstitial injury and fibrosis in diabetic nephropathy. Less