Department of Cardiology, Rui Jin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Cardiovasc Diabetol. 2012 Aug 1;11:90. doi: 10.1186/1475-2840-11-90.
Patients with chronic kidney disease (CKD) are at high risk of cardiovascular disease (CVD). Endothelial progenitor cell (EPCs) dysfunction plays a key role in this pathogenesis. Uremic retention toxins have been reported to be in associated with EPC dysfunction. Advanced glycation end-products (AGEs) free adducts, including nepsilon-(carboxymethyl)lysine (CML) and nepsilon-(carboxyethyl)lysine (CEL), are formed by physiological proteolysis of AGEs and released into plasma for urinary excretion. They are retained in CKD patients and are considered to be potential uremic toxins. Though AGEs have been demonstrated to impair EPC function in various ways, the effect of AGE free adducts on EPC function has not been studied. Thus, we examined the role of CML and CEL in the regulation of growth-factor-dependent function in cultured human EPCs and the mechanisms by which they may affect EPC function.
Late outgrowth EPCs were incubated with different concentrations of CML or CEL for up to 72 hours. Cell proliferation was determined using WST-1 and BrdU assays. Cell apoptosis was tested with annexin V staining. Migration and tube formation assays were used to evaluate EPC function.
Though CML and CEL were determined to have anti-proliferative effects on EPCs, cells treated with concentrations of CML and CEL in the range found in CKD patients had no observable impairment on migration or tube formation. CML and CEL did not induce EPC apoptosis. The reduced growth response was accompanied by significantly less phosphorylation of mitogen-activated protein kinases (MAPKs).
Our study revealed that CML and CEL at uremic concentrations have low biological toxicity when separately tested. The biologic effects of AGE free adducts on the cardiovascular system merit further study.
患有慢性肾脏病（CKD）的患者有发生心血管疾病（CVD）的高风险。内皮祖细胞（EPCs）功能障碍在这一发病机制中起着关键作用。据报道，尿毒症潴留毒素与 EPC 功能障碍有关。晚期糖基化终产物（AGEs）的游离加合物，包括 Nε-（羧甲基）赖氨酸（CML）和 Nε-（羧乙基）赖氨酸（CEL），是 AGEs 生理蛋白水解产生的，并释放到血浆中进行尿排泄。它们在 CKD 患者中被保留下来，被认为是潜在的尿毒症毒素。尽管 AGEs 已被证明以各种方式损害 EPC 功能，但 AGE 游离加合物对 EPC 功能的影响尚未得到研究。因此，我们研究了 CML 和 CEL 在调节培养的人 EPC 中生长因子依赖性功能中的作用及其影响 EPC 功能的机制。
将晚期生长 EPC 与不同浓度的 CML 或 CEL 孵育长达 72 小时。使用 WST-1 和 BrdU 测定法测定细胞增殖。通过 Annexin V 染色测试细胞凋亡。迁移和管形成测定用于评估 EPC 功能。
尽管 CML 和 CEL 被确定对 EPCs 具有抗增殖作用，但用 CKD 患者中发现的浓度处理的细胞在迁移或管形成方面没有观察到明显的损伤。CML 和 CEL 不会诱导 EPC 凋亡。生长反应减弱伴随着丝裂原活化蛋白激酶（MAPKs）的磷酸化明显减少。
我们的研究表明，在尿毒症浓度下，CML 和 CEL 分别测试时具有低生物毒性。AGE 游离加合物对心血管系统的生物学效应值得进一步研究。
