白蛋白刺激肾小管上皮细胞表达基质金属蛋白酶2和9

目的探讨白蛋白对近端肾小管上皮细胞表达基质金属蛋白酶2（MMP-2）和MMP-9的影响。方法大鼠近端肾小管细胞株NRK52E培养至70％或100％融合时，分别给予不同浓度（0．1～1．0g／L）去脂和非去脂牛血清白蛋白（dBSA和BSA）刺激，于24、48、72h收集培养液，用明胶酶谱和Western印迹方法检测培养液MMP-2和MMP-9活性和蛋白水平。结果与空白对照组比较，1．0g／LBSA刺激未完全融合NRK52E72h后，MMP-2和MMP-9活性分别上调276％、176％（P〈0．05）。与刺激24h比较，1．0g／LBSA刺激72h，在未完全融合NRK52E的MMP-2和MMP-9活性分别上调536％、148％；在完全融合NRK52E分别上调212％、184％（P〈0．05）。与完全融合NRK52E比较，1．0g／LBSA刺激未完全融合NRK52E 72h，MMP-2活性上调增加了274％，MMP-9活性上调减少了45．1％（P〈0．05）。dBSA刺激结果与BSA类似。结论白蛋白刺激呈剂量和时间依赖性上调近端肾小管细胞表达MMP-2和MMP-9。细胞完全融合可抑制MMP-2表达，促进MMP-9表达。

Laboratory study on the expression of matrix metalloproteinase-2 and -9 in tubular epithelial cells after exposure to albumin

Objective To study the effect of exposure of proximal tubular cells (PTC) to albumin on MMP-2 and MMP-9 expression. Methods Rat proximal tubular cells NRK52E were cultured to reach 70% confluency or complete confluency. Cells were treated with delipidated and non-delipidated bovine serum albumin (dBSA/BSA) ranging from 0.1~1.0 g/L. Conditioned media was harvested at 24 h, 48 h and 72 h. MMP-2 and MMP-9 activities and protein levels were detected by gelatin zymography and Western blot respectively. Results Zymography of 1 g/L BSA exposed media at 72 h, compared with control samples showed activities of MMP-2 and MMP-9 increased by 276% and 176% respectively in sub-confluent NRK52E (P<0.05). Zymography of samples from different time points of 1 g/L BSA exposure showed that activities of MMP-2 and MMP-9 raised by 536% and 148% respectively in sub-confluent NRK52E raised by 212% and 184% respectively in confluent NRK52E by 72 h, compared to 24 h exposure (P<0.05). Zymography at 72 h of 1 g/L BSA containing media of confluent NRK52E, collagenolytic activity of MMP-2 raised by 274% more than that of sub-confluent NRK52E(P<0.05), collagenolytic activity of MMP-9 raised by 45.1% less than that of sub-confluent NRK52E (P<0.05). Results of dBSA exposure were similar to those of BSA exposure. Conclusions Albumin exposure up-regulates MMP-2 and MMP-9 in NRK52E in a dose- and time-dependent manner. Complete confluence (cell junction) inhibits MMP-2 expression, but promotes MMP-9 expression in NRK52E in the state of albumin exposure.