Exploration of pathogenesis of diabetic complications using transgenic mice and attempts of gene therapy

为了探讨糖尿病并发症的发生机制，为糖尿病并发症的防治提供方向，我们利用新开发的转基因动物模型，研究了微血管和周围神经组织的生化、生理和病理变化。在本研究中，我们使用过表达人醛糖还原酶（AR）的转基因小鼠和缺乏AR的敲除小鼠来研究多元醇途径的作用。另一方面，利用过表达晚期糖基化终产物受体（RAGE）的转基因小鼠，观察RAGE在内皮细胞中过表达对糖尿病并发症发生的影响。静脉注射链脲佐菌素制造糖尿病小鼠模型，随访16周。糖尿病性AR小鼠神经蛋白激酶C （PKC）活性明显降低，而血管组织PKC活性相反升高。这些变化是由于神经中pkc - α的表达增加，血管组织中pkc - β的表达增加。这些改变与糖尿病动物的神经和血管的显著功能和结构病理相关，而在糖尿病ar基因敲除小鼠中未发现。AR抑制剂有效地阻止了所有这些变化。因此，我们认为AR在糖尿病并发症的发生中起着至关重要的作用，抑制AR对糖尿病并发症的预防和治疗是有效的。然而，在非常严重的高血糖情况下，即使是AR敲除小鼠也无法逃脱糖尿病并发症的病理改变，并认为其他机制对组织损伤起作用。作为一种可能的机制，RAGE过表达诱导了比对照糖尿病小鼠更严重的组织损伤，从而提示AGE-RAGE相互作用与糖尿病并发症的发生有关。目前的一系列研究清楚地表明，糖尿病并发症的发生与多种因素有关，我们认为多方向的预防和治疗对临床应用至关重要。少

To explore the mechanisms of diabetic complications and to establish the direction for the prevention and treatment of them, we studied biochemical, physiological and pathological changes in microvessels and peripheral nerve tissues using recently developed transgenic animal models. In this study, we used transgenic mice overexpressing human aldose reductase (AR) and knockout mice that were deficient of AR to examine the role of polyol pathway. On the other hand, transgenic mice that overexpress receptor for advanced glycation endproducts (RAGE) were used to see the effects of RAGE overexpression in the endothelial cells on the development of diabetic complications. These mouse models were made diabetic by intravenous injection of streptozotocin and followed for 16 weeks. The diabetic AR mice exhibited marked depression of protein kinase C (PKC) activity in the nerve while PKC activity was contrariwise elevated in vascular tissues. These changes were due to reduced membrane expression … More of PKC-alpha in the nerve and increased membrane expression of PKC-beta in vascular tissues. These alterations were associated with significant functional and structural pathology in nerve and vessels in diabetic animals and not found in diabetic AR-knockout mice. Inhibitors for AR effectively prevented all the changes. Thus, it was concluded that AR plays a crucial role in the cause of diabetic complications and its inhibition is effective for the prevention and treatment. However, under very severe hyperglycemia, even AR knockout mice could not escape the pathological changes of diabetic complications and other mechanisms were thought to exert for tissue injury. As one possible mechanism, RAGE overexpression induced more severe tissue damage compared to control diabetic mice, thus suggesting the implication of AGE-RAGE interaction for the development of diabetic complications. The current series of studies clearly demonstrated the multiple factors implicating in the cause of diabetic complications and we consider that multi-facet directions for the prevention and treatment will be essential for the clinical applications. Less