晚期糖基化终产物诱导人肾小管上皮细胞表达结缔组织生长因子

Advanced glycosylation end products induce the expression of connective tissue growth factor in human renal proximal tubular epithelial cells

目的观察晚期糖基化终产物(AGE)修饰的牛血清白蛋白(BSA)对体外培养的人近端肾小管上皮细胞株(HK-2细胞)表达结缔组织生长因子(CTGF)的影响,并探讨可能的作用途径。方法将HK-2细胞在体外与不同浓度的AGE-BSA和BSA共同培养。间接免疫荧光法检测糖基化终产物受体(RAGE)。免疫印迹法观察HK-2细胞表达的CTGF蛋白质,ELISA和免疫印迹法检测TGF-β1的合成和分泌。结果在HK-2细胞的胞膜和胞质存在RAGE的表达。AGE-BSA以时间和剂量依赖方式上调HK-2细胞CTGF的表达,8、24、48及72 h组分别为0 h组的117%、138%、257%及339%；20、50及100 mg/L组分别为0 mg/L组的186%、240%及287%。在一定的剂量和时间范围内,AGE-BSA能够诱导TGF-β1蛋白质的表达和分泌。抗RAGE和抗TGF-β1的单克隆抗体能够部分抑制AGE-BSA诱导的CTGF蛋白质表达。结论人肾小管上皮细胞表面存在RAGE的表达。AGE-BSA可能部分地通过RAGE介导TGF-β1表达上调,诱导HK-2细胞CTGF表达。

Objective To investigate the effects of AGE-modified bovine serum albumin （AGE-BSA） on the expression of connective tissue growth factor（CTGF） in human renal proximal tubular epithelial cells （HK-2 cells） and to explore the possible role. Methods HK-2 cells were cultured in vitro with indicated concentration of AGE-BSA or BSA. The localization of the receptor for AGEs （RAGE） in HK-2 cells was detected by immunofluorescent staining. The expression of CTGF protein was examined by Western blotting. The production of TGF-β1 was measured by ELISA and Western blotting. Results RAGE was expressed in the plasma and membrane of HK-2 cell line. In the AGE-BSA group, the expression of CTGF protein significandy increased in a time- and dosedependent manner. CTGF expression in AGE-BSA 8 h,24 h,48 h and 72 h groups was 117%, 138%,257% and 339% of 0 h group respectively,while in AGE-BSA 20,50 and 100 mg/L groups was 186%,240% and 287% of 0 mg/L group respectively. AGE-BSA also induced the secretion of TGF-β1 in a dose-dependent manner in 24 hours and the concentration of AGE-BSA between 0 and 100 mg/L. AGE-induced up-regulation of CTGF protein at 48 hours was blocked partially by neutralizing RAGE antibodies and TGF-β1 antibodies. Conclusions Human renal proximal tubular epithelial cells express RAGE. The up-regulation of the expression of CTGF induced by AGE-BSA may be partially mediated through a RAGE-TGF-β1- dependent pathway.