白蛋白超负荷对肾小管上皮细胞线粒体膜电位及其超微结构的影响

Effects of albumin overload on mitochondrial membrane potential and ultrastructural changes in renal tubular epithelial cells

目的观察尿蛋白的主要成分白蛋白超负荷对体外培养的肾小管上皮细胞(HK-2)线粒体膜电位及其超微结构的影响。方法以体外培养的HK-2细胞为研究对象,以不同浓度白蛋白处理HK-2细胞,采用线粒体膜电位探针JC-1检测白蛋白超负荷对肾小管上皮细胞线粒体膜电位变化的影响,通过电镜观察白蛋白超负荷对HK-2细胞线粒体超微结构的作用。结果JC-1检测结果显示,与正常组(白蛋白浓度0 g/L组)红/绿荧光强度的比值2.34±0.21比较,白蛋白浓度4 g/L、8 g/L、16 g/L组红/绿荧光强度的比值分别为0.83±0.09、0.41±0.07、0.38±0.08,红/绿荧光强度的比值逐渐降低,差异具有统计学意义(F=162.794,P<0.001),且各组间比较差异均有统计学意义(均P<0.05)。电镜观察结果显示,白蛋白超负荷诱导了HK-2细胞内线粒体肿胀、嵴的走向紊乱、断裂或消失,空泡化,同时双层膜结构增多。结论白蛋白超负荷可以诱导肾小管上皮细胞线粒体膜电位下降、线粒体损伤及自噬泡增多,提示线粒体损伤及自噬改变可能是白蛋白超负荷诱导肾小管上皮细胞损伤的机制之一。

Objective To investigate effects of albumin overload on mitochondrial membrane potential and ultrastructural changes in renal tubular epithelial cells(HK-2). Methods Vitro-cultured HK-2 cells were treated with different concentrations of albumin.The mitochondrial membrane potential in HK-2 cells was detected by fluorescence probe JC-1, and the electron microscopy was used to detect the mitochondrial ultrastructure of cells. Results JC-1-detected red/green ratio was 2.34±0.21 at 0 g/L of albumin treatment, 0.83±0.09 at 4 g/L, 0.41±0.07 at 8 g/L, 0.38±0.08 at 16 g/L albumin overload, which showed a gradually decreased red and green fluorescence intensity ratio along with increased albumin overload(F=162.794, P<0.001), and with significant differences in the ratio among groups(all P<0.05). Albumin overload-induced mitochondrial abnormality in transmission electron microscope included mitochondrial swelling, disordered cristae arrangement, cristae lysis and cavitation, and the increase of bilayer membrane structures in HK-2 cells. Conclusions Albumin overload can induce the decline of mitochondrial membrane potential, mitochondrial damage and autophagy in renal tubular epithelial cells, which suggest that mitochondrial damage and autophagy may be one of the mechanisms of albumin overload-induced renal tubular epithelial cell injury.