Department of Endocrinology, Zhongnan Hospital, Wuhan University, Wuhan 430071, China.
J Cell Biochem. 2010 Apr 15;109(6):1210-21. doi: 10.1002/jcb.22503.
Glucose fluctuations are strong predictor of diabetic vascular complications. We explored the effects of constant and intermittent high glucose on the proliferation and collagen synthesis of cultured rat mesangial cells. Furthermore, the possible involvement of osteopontin (OPN) was assessed. In rat mesangial cells cultured in 5, 25, or 5 mmol/L alternating with 25 mmol/L glucose in the absence or presence of neutralizing antibodies to OPN, beta3 integrin receptor and beta5 integrin receptor, the cell proliferation, collagen synthesis, and the expression of OPN and type IV collagen were assessed. In cultured mesangial cells, treatment with constant or intermittent high glucose significantly increased [(3)H]thymidine incorporation in a time-dependent manner. A modest increase was observed at 12 h, and further deteriorated afterwards, and reached the maximum incorporation at 48 h. Treatment with constant high glucose for 48 h resulted in significant increases in [(3)H]thymidine incorporation, cell number, [(3)H]proline incorporation, mRNA, and protein levels of type IV collagen and OPN compared with mesangial cells treated with the normal glucose, which were markedly enhanced in cells exposed to intermittent high glucose medium. In addition, neutralizing antibodies to either OPN or its receptor beta3 integrin but not neutralizing antibodies to beta5 integrin can effectively prevented proliferation and collagen synthesis of mesangial cells induced by constant or intermittent high glucose. Intermittent high glucose exacerbates mesangial cells growth and collagen synthesis by upregulation of OPN expression, indicating that glycemic variability have important pathological effects on the development of diabetic nephropathy, which is mediated by the stimulation of OPN expression and synthesis.
血糖波动是糖尿病血管并发症的强预测因子。我们探讨了持续和间歇性高血糖对培养的大鼠肾小球系膜细胞增殖和胶原合成的影响。此外，还评估了骨桥蛋白（OPN）的可能参与。在无或存在针对 OPN、β3 整合素受体和β5 整合素受体的中和抗体的情况下，将大鼠肾小球系膜细胞在 5、25 或 5 mmol/L 交替 25 mmol/L 葡萄糖中培养，评估细胞增殖、胶原合成以及 OPN 和 IV 型胶原的表达。在培养的系膜细胞中，持续或间歇性高葡萄糖处理以时间依赖的方式显著增加[3H]胸苷掺入。在 12 小时观察到适度增加，随后恶化，并在 48 小时达到最大掺入。与正常葡萄糖处理的系膜细胞相比，持续高葡萄糖处理 48 小时导致[3H]胸苷掺入、细胞数量、[3H]脯氨酸掺入、IV 型胶原和 OPN 的 mRNA 和蛋白水平显著增加，而在间歇性高葡萄糖培养基中暴露的细胞中则显著增强。此外，针对 OPN 或其受体β3 整合素的中和抗体，但不是针对β5 整合素的中和抗体，可有效阻止由持续或间歇性高葡萄糖诱导的系膜细胞增殖和胶原合成。间歇性高葡萄糖通过上调 OPN 表达加重系膜细胞生长和胶原合成，表明血糖变异性对糖尿病肾病的发展具有重要的病理作用，这是通过刺激 OPN 表达和合成介导的。
