| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2009: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2008: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2007: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Research Abstract |
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
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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
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