肾病综合征患者尿白蛋白诱导HK-2细胞上调内皮素1的表达

Urine albumin from nephrotic syndrome patients up-regulates endothelin-1 expression in HK-2 cells

目的探讨肾病综合征(NS)患者尿白蛋白对人近端肾小管上皮细胞(HK-2)合成内皮素1(ET-1)的调节作用。方法从NS患者尿中提取纯化白蛋白,分析鉴定并用以刺激 HK-2细胞。通过逆转录多聚酶链反应(RT-PCR)法和间接免疫荧光法观察不同时间及不同浓度的白蛋白对HK-2细胞表达ET-1 mRNA及蛋白质的影响,并以正常人血清白蛋白(HSA)作对照。结果尿白蛋白及HSA均能上调HK-2细胞ET-1 mRNA及蛋白质表达,随着刺激时间延长表达逐渐增强,到达峰值后又逐渐下降至基线水平。随着尿白蛋白及HSA浓度的增加,HK-2 细胞表达ET-1 mRNA也不断增强。血清白蛋白需达2．5 mg／nl才具有显著上调HK-2细胞 ET-1 mRNA表达效应,而0．5-mg／ml尿白蛋白即可明显上调(P<0．05)。结论 NS患者尿白蛋白与正常人血清白蛋白均可上调HK-2细胞表达ET-1,而NS患者尿白蛋白的作用强于正常人血清白蛋白。

Objective To investigate the role of urine albumin from nephrotic syndrome patients on expression of endothelin （ET）-I in human proximal tubular epithelial cells （HK-2）. Methods Proteins were precipitated with polyethylene glycol, and albumin were purified by Sephadex-75 column chromatography from urine taken from nephrotic syndrome patients. The HK-2 cells were divided into two groups： one group incubated with the urine albumin from nephrotic syndrome patients, another with HSA. The expression of ET-1 mRNA of HK-2 cells was assessed by RT-PCR, and the level of ET-1 protein was assessed by indirect immunofluorescence. Results The urine albumin and lISA up-regulated the expression of ET-1 mRNA and protein in HK-2 ceils. The expression of ET-1 protein was associated with the stimulation time, and increased in dose-dependent manner. The expression of ET-1 mRNA in HK-2 cells increased significantly when cultured with urine albumin （0.5 mg/ml） from nephrotic syndrome （P 〈 0.05）. However, only when the HK-2 cells were cultured with HSA at 2.5mg/ml, the ET-1 mRNA were markedly increased. Conclusion The urine albumin from nephrotic syndrome patients and normal serum albumin can up-regulate expression of ET-1 in HK-2 cells, and the urine albumin stimulates ET-1 synthesis by HK-2 ceils to a higher extent as compare to that of normal serum albumin.