慢性间断性缺氧对小鼠肾组织结构、基质金属蛋白酶及其组织抑制因子表达的影响

Effect of chronic intermittent hypoxia on structure of kidney and expressions of matrix metaiioproteinase and tissue inhibitor of metaiioproteinase in mice kidney

目的 观察慢性间断性缺氧（chronic intermittent hypoxia，CIH）对小鼠肾脏结构，基质金属蛋白酶-1、9（matrixmetallo-proteinase-1、9，MMP-1、9）及其组织抑制因子-1（tissue inhibitor of metalloproteinase-1，TIMP-1）表达变化的影响，探讨其在睡眠呼吸暂停综合征（sAs）肾损害中的作用。方法 将30只ICR小鼠随机分为4组，空气模拟对照组（10只）、CIH2周组（5只）、CIH4周组（5只）、CIH8周组（10只）。采用光镜下病理检查和免疫组织化学方法观察实验小鼠肾组织结构变化和MMP-1、MMP-9及TIMP-1在肾脏的表达。结果 ①CIH各组见肾小管上皮细胞肿胀、空泡、颗粒变性，随缺氧时间延长，变性范围扩大，主要表现为近曲小管的病理改变，其中8周组可见部分肾小管坏死。②MMP-1、MMP-9及TIMP-1主要表达于肾小管上皮细胞。③与对照组比较，CIH各组MMP-1表达均明显减少（P均d0．01），2周时降至最低，随后MMP-1表达略有回升；CIH组间两两比较差异无显著性（P〉0．05）。MMP-9在2周组的表达水平与对照组相比均显著升高（P〈0．01），而在4、8周两组则显著降低（P均d0．01）。CIH各组TIMP-1均呈高表达（P均〈0．01），其中高峰表达在2周缺氧组。CIH各组MMP-1／TIMP-1均显著降低（P均〈0．05），其中2周组达最低（P〈0．01），CIH各组间两两比较差异无显著性（P〉0．05）。MMP-9／TIMP-1随间断缺氧时间的延长呈下降趋势，CIH4周、8周两组均低于对照组（P〈0．05），最低表达在8周组（P〈0．01）。④随间断缺氧时间延长，TIMP-1与MMP-1之间存在负相关关系（r=-0．769，Pd0．01）；TIMP-1与MMP-9之间存在正相关关系（r=0．392，PdO．05）。结论 CIH可引起实验小鼠肾小管变性、坏死等病理变化；同时肾小管上皮细胞MMP-1、MMP-9、TIMP-1表达异常；MMP-1／TIMP-1与MMP-9／TIMP-1下降，这可能参与了SAS肾损害的发生发展过程。

Objective To explore the effect of chronic intermittent hypoxia （CIH）, an important pathophysiological state of sleep apnea syndrome,on the renal structure and expression of matrix metallo- proteinase-1,9 （MMP-1,9） and tissue inhibitor of metalloproteinase-1 （TIMP-1） in mice kidney. Methods Thirty ICR mice were randomly divided into four groups,control group （sham CIH, 10 mice）and three CIH groups,which were exposed to intermittent hypoxia for 2 weeks （5 mice） ,4 weeks （5 mice） and 8 weeks （10 mice） respectively. Histopathological method was applied to observe the renal structure and immunohistochemistry was used to detect the expression of MMP-1,9 and TIMP-1 in mice kidney. Results ①Pathological changes mainly appeared in proximal convoluted tubule. Swelling, vacuolar degeneration and granular degeneration were found in epithelial cells of renal tubule in CIH groups and the areas of degeneration were expanding when CIH continued. Necroses were found in part of renal tubule of 8 weeks group. ②MMP-1, MMP-9 and TIMP-1 were mainly expressed in tubular cells. ③Compared with that of control group, the expression of MMP-1 decreased significantly in three CIH groups （all P 〈 0.01）. Expression of MMP-1 was lowest at 2 weeks,and increased slightly after that,but there were no significant differences among CIH groups（ P 〉0.05）. Expression of TIMP-1 and MMP-9 in 2 weeks group were both significantly higher than that of control group（ P 〈0.01）, but kept decreasing along with CIH. Expression of MMP-9 in 4 weeks group and 8 weeks group were lower than that of control group（ P 〉0.01） ,while the expression of TIMP-1 of all CIH groups were higher than that of control group（ P 〉0.01）, then increased slightly with CIH continued. MMP-1/TIMP-1 of all CIH groups were significantly lower than that of control group（ P〉0.05） and dropped to nadir after 2 weeks CIH（ P〉0.01）. There were no significant differences among three CIH groups（ P 〉0.05）. MMP-9/TIMP-1 was declining when CIH continued. MMP-9/TIMP-1 of 4 weeks group and 8 weeks were significantly lower than that of control group（ P 〈0.05）. TIMP-1 was negatively correlated with MMP-1 （ r =-0. 769, P 〉0.01）, and was positively correlated with MMP-9 （ r =0. 392, P 〈 0.05）. Conclusions CIH resulted in degeneration and necroses in the renal tubule, and abnormal expression of MMP-1,9 and TIMP-1 ,aswell as decreased ratios of MMP-1/TIMP-1 and MMP-9 / TIMP-1 in the epithelial cells of renal tubule,which suggested that CIH might contribute to the development of renal injury in sleep apnea syndrome.