The establishment of new animal models for diabetic nephropathy (DN) and the development of Midkine-targeted therapy against DN.

我们描述了两种有趣的糖尿病肾病小鼠模型的发病机制；即1)链脲佐菌素（STZ）治疗的midkine (Mdk)+/+小鼠（129/SV背景）糖尿病模型，以及2)β3细胞特异性钙调素过表达小鼠（CaMTg小鼠）。首先，缺乏生长因子midkine （Mdk-/-）的小鼠表现出明显较轻的肾病，尽管Mdk-/-和+/+小鼠在注射STZ后表现出相似程度的高血糖。MK在Mdk+/+型糖尿病肾病小鼠的肾小球系膜以及暴露于高糖环境的原代培养系膜细胞中被诱导表达。Mdk-/-系膜细胞在高葡萄糖负荷下表现出蛋白激酶C和细胞外信号调节激酶磷酸化减少，转化生长因子-β_1的产生减少。在高糖条件下，外源性MK恢复了Mdk-/-细胞胞外信号调节的激酶磷酸化，而MK反义寡核苷酸抑制了Mdk-/ +细胞的磷酸化。这表明MK加速了肾病中由高血糖引起的细胞内信号网络。其次，CaMTg小鼠在3月龄及之后表现出明显的蛋白尿。6月龄和9月龄CaMTg小鼠出现结节状病变，9月龄CaMTg小鼠偶尔出现渗出性病变。在6月和9月大的CaMTg中观察到传入和传出小动脉的透明质化。内皮型一氧化氮氧化酶合成酶（eNOS）表达水平降低，VEGF表达水平升高，主要分布于足细胞。VEGF受体(VEGFR)-1在6M CaMTg肾中的表达低于ntg1。在VEGFR-2中，CaMTg和nTg肾脏之间没有这种差异。6个月和9个月大的CaMTg小鼠与nTg小鼠相比，血栓调节素阳性血管面积增加。这些发现表明CaMTg小鼠出现了最典型的人类糖尿病肾病病变。VEGF水平升高，eNOS和VEGFR-1表达减少，可能导致VEGFR-2信号优先激活，最终导致内皮细胞增殖。我们认为这些模型对于研究糖尿病肾病的发病机制和开发新的治疗方法非常有用。少

We characterized the pathogenesis of two interesting mice models for diabetic nephropathy ; i.e., 1) Streptozotocin (STZ)-treated diabetic model in midkine (Mdk)+/+ mice (129/SV background), and 2) β3 cell-specific calmodulin overexpressing mice (CaMTg mice).First, mice deficient in the growth factor midkine (Mdk-/-) exhibited strikingly milder nephropathy, even though Mdk-/- and +/+ mice showed similar extents of hyperglycemia after STZ injection. MK expression was induced in the glomerular mesangium of Mdk+/+ mice with diabetic nephropathy, and in primary cultured mesangial cells exposed to high glucose. Mdk-/- mesangial cells exhibited reduced phosphorylation of protein kinase C and extracellular signal-regulated kinase, and reduced production of transforming growth factor-β_1 upon high glucose loading. Exogenous MK restored extracellular signal-regulated kinase phosphorylation in Mdk-/- cells under high glucose conditions, whereas a MK antisense oligonucleotide suppressed it in Mdk … More +/+ cells. This suggests that MK accelerates the intracellular signaling network evoked by hyperglycemia in nephropathy.Second, CaMTg mice showed evident albuminuria at 3 months of age and thereafter. Nodular lesions were seen in CaMTg mice at 6 and 9 months of age, and even exudative lesions occasionally appeared in 9 month-old CaMTg mice. Hyalinosis of the afferent and efferent arterioles was observed in 6- and 9-month-old CaMTg. The expression level of endothelial nitric oxidase synthase (eNOS) was decreased and that of VEGF, mainly distributed in the podocytes, was elevated in the 3- and 6-month-old CaMTg kidney. VEGF receptor (VEGFR)-1 was less expressed in the 6M CaMTg kidney than nTg one. Such difference between the CaMTg and nTg kidneys was not seen for VEGFR-2. There was an increase of the thrombomodulin-positive vascular area in the 6- and 9-month-old CaMTg mice compared to the nTg ones. These findings indicate CaMTg mice developed most typical distinct lesions of human diabetic nephropathy. The elevated VEGF level and diminished eNOS and VEGFR-1 expression may result in preferential activation of the VEGFR-2 signaling and eventual proliferation of the endotherial cells.We propose these models are very useful for investigations of the pathogenesis of diabetic nephropathy and for the development of new treatments. Less