Ceriello A, Morocutti A, Mercuri F, Quagliaro L, Moro M, Damante G, Viberti G C
Department of Pathology and Medicine, Experimental and Clinical, University of Udine, Italy.
Diabetes. 2000 Dec;49(12):2170-7. doi: 10.2337/diabetes.49.12.2170.
There is an individual susceptibility to diabetic nephropathy, and oxidative stress is believed to play an important role in the pathogenesis of diabetic complications. Active oxygen species induce antioxidant enzyme expression in tissues, an effect considered to be a defensive mechanism. To test whether altered intracellular antioxidant enzyme production might explain the predisposition to diabetic nephropathy, we studied the effect of long-term (12 weeks) exposure to normal (5 mmol/l) or high (22 mmol/l) glucose concentrations on fibroblast antioxidant enzyme gene expression and protein activity in type 1 diabetic patients with and without nephropathy, nondiabetic nephropathic patients, and nondiabetic control subjects. Under conditions of normal glucose concentration in the culture media, CuZnSuperoxide-dismutase, MnSuperoxide-dismutase, catalase, and glutathione-peroxidase activity and mRNA expression were not different among the four groups. Under high-glucose conditions, CuZnSuperoxide-dismutase mRNA and activity increased similarly in all groups (P < 0.001 vs. basal), whereas MnSuperoxide-dismutase did not change. In contrast, catalase mRNA and activity as well as glutathione-peroxidase mRNA and activity increased in fibroblasts from type 1 diabetic patients without nephropathy (P < 0.001), in fibroblasts from nondiabetic nephropathic patients (P < 0.001), and in fibroblasts from nondiabetic control subjects (P < 0.001), but not in fibroblasts from type 1 diabetic patients with nephropathy. Exposure to high glucose concentrations significantly increased lipid peroxidation in cells, higher levels being found in cells from diabetic patients with nephropathy (P < 0.001). These data, while confirming that exposure to high glucose concentrations induces an antioxidant defense in skin fibroblasts from normal subjects, demonstrate a failure of this defensive mechanism in cells from type 1 diabetic patients with nephropathy, whereas skin fibroblasts from diabetic patients without complications or from nondiabetic nephropathic patients have an intact antioxidant response to glucose-induced oxidative stress.
个体对糖尿病肾病存在易感性，氧化应激被认为在糖尿病并发症的发病机制中起重要作用。活性氧会诱导组织中抗氧化酶的表达，这种效应被视为一种防御机制。为了检验细胞内抗氧化酶产生的改变是否可以解释糖尿病肾病的易感性，我们研究了长期（12周）暴露于正常（5 mmol/l）或高（22 mmol/l）葡萄糖浓度对1型糖尿病肾病患者和非糖尿病肾病患者以及非糖尿病对照受试者成纤维细胞抗氧化酶基因表达和蛋白活性的影响。在培养基葡萄糖浓度正常的情况下，四组之间铜锌超氧化物歧化酶、锰超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶的活性及mRNA表达没有差异。在高糖条件下，所有组的铜锌超氧化物歧化酶mRNA和活性均类似增加（与基础值相比，P < 0.001），而锰超氧化物歧化酶没有变化。相比之下，无肾病的1型糖尿病患者成纤维细胞、非糖尿病肾病患者成纤维细胞和非糖尿病对照受试者成纤维细胞中的过氧化氢酶mRNA和活性以及谷胱甘肽过氧化物酶mRNA和活性增加（P < 0.001），但1型糖尿病肾病患者的成纤维细胞中没有增加。暴露于高葡萄糖浓度会显著增加细胞中的脂质过氧化，糖尿病肾病患者细胞中的脂质过氧化水平更高（P < 0.001）。这些数据在证实暴露于高葡萄糖浓度会诱导正常受试者皮肤成纤维细胞产生抗氧化防御的同时，也表明这种防御机制在1型糖尿病肾病患者的细胞中失效，而无并发症的糖尿病患者或非糖尿病肾病患者的皮肤成纤维细胞对葡萄糖诱导的氧化应激具有完整的抗氧化反应。
