SPARC在常染色体显性多囊肾病患者体液中的表达及其分泌研究

Expression and secretion of SPARC in body fluid of patients with autosomal dominant polycystic kidney disease

目的研究富含半胱氨酸的酸性分泌糖蛋白(SPARC)在常染色体显性多囊肾病(ADPKD)患者体液中的浓度及其分泌来源。方法采用ELISA法测定ADPKD患者血浆、尿液、囊肿液以及正常人血浆、尿液中的SPARC浓度;采用Westernblot方法比较检测人肾小管上皮细胞(HKC)和囊肿衬里上皮细胞培养液中的SPARC蛋白水平。结果ADPKD患者囊肿液中SPARC浓度为3628.75±1445.90ng/ml,显著高于血浆和尿液中的SPARC浓度(P<0.01);ADPKD组尿液中的SPARC含量比对照组明显升高(1253.16±544.81ng/mlvs123.91±28.37ng/ml,P<0.01),而两组血浆中SPARC浓度无明显差别。HKC和囊肿衬里上皮细胞培养液中均检测到SPARC蛋白表达,光密度检测两种细胞所分泌的SPARC蛋白与相应的GAPDH条带光密度比值分别为35.56%和71.15%。结论ADPKD患者囊液和尿液中增多的SPARC可能来自囊肿衬里上皮细胞及扩张的小管和集合系统。

Objective To investigate the concentration of secreted protein acidic and rich in cysteine (SPARC) in body fluid of patients with autosomal dominant polycystic kidney disease (ADPKD) and the origin of its secretion. Methods The concentration of SPARC in plasma, urine and cystic fluid from patients with ADPKD and healthy individuals was measured with ELISA. The content of SPARC protein in the culture medium of cystic epithelial cells was detected by Western blot. Results The concentration of SPARC in cyst fluid of ADPKD patients [( 3 628.75± 1 445.90) ng/ml] was much higher than that in their plasma and urine (P<0.01). The concentration of SPARC in their urine was higher than that in control group ( 1 253.16±544.81ng/ml vs 123.91±28.37, P<0.01). There was no significant difference in plasma content of SPARC between two group. Culture media from separate cultures of HKC cells or cyst-lining epithelial cells were found to have SPARC protein, and the level was significantly higher in the latter. The ratio of optical density values of SPARC protein secreted by HKC cells and cyst-lining epithelial cells to that of their corresponding GAPDH were 35.56% and 71.15%, respectively, as detected by densitometric analysis. Conclusion The increased content of SPARC in cyst fluid and urine of ADPKD patients may be derived from lining epithelial cells of the cyst, dilated renal tubules and collecting system.