霉酚酸酯对实验性大鼠IgA肾病的MMP-9、TIMP-1的影响

Effect of mycophenolate mofetil on MMP-9 and TIMP-1 in renal tissues of IgA nephropathy rats

目的：观察霉酚酸酯（MMF）对实验性IgA肾病（IgAN）大鼠肾组织基质金属蛋白酶（MMP-9）及其组织抑制剂（TIMP-1）表达的影响，探讨 MMF 对 IgAN 的治疗作用以及其可能的作用机制。方法将24只（6周龄）雄性Wistar大鼠随机分为3组（每组各8只），分别为模型组、MMF组、对照组。模型组、MMF组均采用灌服牛血清白蛋白（BSA）和尾静脉注射脂多糖（LPS）的方法建立IgAN模型，共8周，于第9周起MMF组给MMF每日灌胃1次，按10 mg＆#183;kg-1＆#183;d-1，对照组和模型组给予等量蒸馏水灌胃，持续至12周末。三组均每4周检测1次尿红细胞计数、24 h尿蛋白定量；于12周末测定血生化指标，并观察肾脏病理改变和免疫复合物沉积情况，免疫组织化学方法检测肾组织中MMP-9、TIMP-1的表达。结果前4周，各组尿红细胞计数、尿蛋白定量比较差异无统计学意义（P＞0.05）；第6周至8周末，模型组与 MMF组尿红细胞及尿蛋白定量明显升高，与对照组比较差异有统计学意义（P＜0.05）；第10～12周末，MMF 组尿红细胞及尿蛋白定量较模型组明显减少，差异有统计学意义（P＜0.05）；血生化指标各组间无统计学差异（P＞0.05）。与对照组相比，模型组肾小球系膜区增宽，系膜细胞、系膜基质增生，伴有强IgA荧光及较多电子致密物沉积，MMP-9、TIMP-1均明显升高（P＜0.05），其中MMF组上述病理改变均明显轻于模型组，MMP-9及TIMP-1表达均明显低于模型组（P＜0.05）。结论 MMF可降低尿蛋白，减少免疫复合物在肾组织中的沉积，推测其治疗IgAN的病理机制可能是通过调节MMP-9、TIMP-1的表达延缓肾脏纤维化。

Objective To observe the expressions of MMP-9 and TIMP-1 in renal tissue of IgA nephropathy rats intervened by mycophenolate mofetil（MMF）, and to explore the improved IgAN mechanism. Methods Twenty-four male Wistar rats were randomly divided into three groups：MMF-treated group, IgAN model group and normal control group（eight in each group）. Rat IgAN models of the first two groups were established by oral administration of BSA and time-controlled injection of LPS into phallic vein. After that MMF-treated group was treated with oral administration of MMF 10 mg＆#183;kg-1＆#183;d-1 and the other two groups were treated with equal quantity of distilled water（From ninth week, once a day, to twelfth weekend）. Urine RBC, 24 h urinary protein count were measured per 4 weeks for every group. At the end of 12 th week, renal function, liver function and blood fat were measured, and renal pathological changes and deposits of immune complexes were observed.Immunohistochemistry was used to examine the protein expressions of MMP-9 and TIMP-1 in renal tissues. Results The first 4 weeks, groups to compare the difference had no sense of statistics（P〉0.05）. At the end of the 6th and 8th week, urine RBC and 24 h urinary protein count of MMF-treated group and IgAN model group were obviously higher than that of the normal control group（P〈0.05）. At the end of the 10th and 12 th week, compared with the normal control group, urine RBC and 24 h urinary protein count of MMF-treated group got remarkablely lower（P〈0.05）. Renal function, liver function and blood fat had no significant differences among all the groups, and showed that no statistical significance （P〉0.05）. Compared with the normal group, the mesangial cells proliferated and mesangial matrix increased obviously with strong IgA deposition and many electron dense deposits. Also the expression levels of protein of MMP-9 and TIMP-1 in the model group were remarkably up-regulated （P〈0.05）. MMF administration relieved all changes （P〈0.05）. Conclusion MMF can reduce urinary protein and immune complexes in renal tissue deposition. Speculated that its treatment of IgAN pathological mechanism may be through regulating the expression of MMP-9 and TIMP-1 delay renal fibrosis.