Regulation of smooth muscle cell function and arteriogenesis by glycated collagen and its receptor

已有研究表明，糖尿病患者和实验动物模型在动脉闭塞时形成侧支血管的能力较弱。然而，糖尿病动脉生成受损的分子和细胞机制尚不清楚。在这项研究中，我们研究了晚期糖基化终末产物AGE及其受体RAGE在糖尿病相关的受损的平滑肌细胞(SMC)功能和动脉形成中的作用。在乙醇醛诱导的糖化型I型纤维型胶原(AGE-胶原)上，与天然胶原培养的SMC相比，基础或PDGF刺激的SMC迁移明显减少。对I型胶原候选受体的分析表明，α2整合素的表达受到抑制，而αv整合素的表达水平在AGE-胶原上上调。在AGE胶原上培养可抑制血管内皮生长因子(VEGF)的分泌和mRNA表达，但增强血管生成抑制因子血栓反应蛋白-1的mRNA表达。为了检测体内动脉的形成，我们将含有血管内皮生长因子的基质植入链脲佐菌素诱导的糖尿病小鼠或对照组小鼠的皮下。在糖尿病小鼠，α-肌动蛋白阳性的系膜细胞或周细胞迁移到基质细胞的数量比对照组减少了25%。同样，CD31阳性的内皮细胞在糖尿病小鼠中渗透较少。重要的是，在RAGE缺乏的小鼠中，糖尿病时SMC和内皮细胞向Matrigel迁移受损的情况完全恢复。因此，年龄-RAGE系统似乎在糖尿病动脉生成受损中起着重要作用。

It has been shown that patients and experimental animal models with diabetes have a lesser ability to develop collateral blood vessels in arterial occlusion. However, the molecular and cellular mechanism underlying impaired arteriogenesis in diabetes is not known. In the present study, we examined the role of advanced glycation endproducts, AGE, and its receptor, RAGE, in diabetes-associated impaired smooth muscle cell (SMC) function and arteriogenesis. On glycolaldehyde-induced glycated form of type 1 fibrillar collagen (AGE-collagen), basal or PDGF-stimulated SMC migration was markedly decreased as compared with SMC cultured on native collagen. Analyses of candidate receptors for type 1 collagen revealed that expression of α2 integrins is suppressed, while levels of αv integrins are upregulated in SMC cultured on AGE-collagen. Culture on AGE collagen suppresses secretion and mRNA expression of vascular endothelial growth factor (VEGF), but enhances mRNA expression of thrombospondin-1, an inhibitor of angiogenesis. To examine arteriogenesis in vivo, we subcutaneously implanted VEGF-containing matrigel to streptozotocin-induced diabetic or control mice. In diabetic mice, numbers of α-actin positive SMC or pericytes migrated into matrigel was decreased by 25% as compared with control mice. Similarly CD31-positive endothelial cells infiltrated less in diabetic mice. Importantly, impaired migration of both SMC and endothelial cells into matrigel in diabetes was completely restored in RAGE-deficient mice. Thus, AGE-RAGE system appears to play fundamental role in impaired arteriogenesis in diabetes.