系膜细胞在狼疮肾小鼠肾纤维化中的作用及ROS调控机制研究

The mechanism of Lupus nephritis (LN) has not been understood. Experimental studies have demonstrated that profoundly proliferating mesangial cells transform into myofibroblast, leading to ultimate matrix expansion and fibrosis. These studies are indicative for pathogenesis of general glomerulosclerosis. However, the model is unable to represent characteristics of LN. For instance, the model failed to demonstrate lupus glomerulosclerosis; the model lacks genetic background dictating disease formation. Although reactive oxygen species (ROS) is evident on renal interstitial resident fibroblast transformation into myofibroblast, but there is no any evidence to explain the glomerulosclerosis. Hence, we hypothesized that mesangial cell derived-myofibroblasts mediate the lupus glomerulosclerosis, and lupus glomerulosclerosis is regulated by altered ROS. To answer these questions, we propose to utilize the remarkable spontaneous lupus glomerulonephritis mouse model NZB/ NZWFl. Mice will be euthanized at different ages (weeks old) to reflect glomerulosclerosis severity by the way of testing mesangial cell generation, myofibroblast expression and the ROS level in mesangial cell. The kinetics will be correlated with glomerulosclerosis severity as well as disease progression. Regarding regulation, we hypothesize that(1) ROS functionally regulates mesangial cells transformation to, myofibroblast leading to glomerulosclerosis in LN; (2) ROS concentration in mesanglial cells is elevated in glomerulosclerosis and elevation kinetic associates with disease progression. The significance of this proposed study is to elucidate the mechanism of lupus glomerulosclerosis and its regulation.

狼疮肾炎(LN)的病因和机制尚不清楚。研究表明，系膜细胞转化为肌成纤维细胞可致基质增生及肾脏纤维化，但其病理特征并非LN特征，原因可能是实验模型为正常鼠，不具备LN易感基因；虽然发现活性氧自由基（ROS）在系膜基质纤维化调控中起一定作用，但尚无肾脏纤维化调控机制的确切研究结果。据既往研究结果，我们推测系膜细胞转化为肌成纤维细胞从而诱导狼疮肾纤维化，ROS可能是该过程重要的调节机制。本研究拟应用自发性LN鼠模型NZB/ NZWFl，通过监测不同鼠龄模拟肾纤维化的进程，检测肾小球系膜细胞增殖、肌成纤维细胞表达及系膜细胞内ROS表达水平的改变情况，以验证上述假设。以其证明：(1)ROS调控系膜细胞转变为肌成纤维细胞，致LN中肾小球硬化；(2)肾小球硬化时系膜细胞内ROS浓度增高，其程度与疾病进展相关。从而解释LN肾小球硬化的发生及调控机制。

系统性红斑狼疮（Systemic lupus erythematosus, SLE）是一种原发性弥漫性自身免疫性疾病，系统性红斑狼疮可导致多脏器受累，其中狼疮性肾炎（lupus nephritis，LN）是 SLE最常见的并发症。狼疮肾炎纤维化的机制目前还不清楚，在我们的研究中发现系膜细胞与活性氧自由基参与了狼疮肾纤维化的过程。本课题组以NZBWF1小鼠为狼疮鼠模型，C57BL/6小鼠为正常对照组。分别于8,、12周、16周时，取肾组织，对肾组织石蜡切片进行苏木素伊红(hematoxylin and eosin，HE)、马松（Masson）染色观察小鼠肾脏病变情况，BrdU 掺入法观察肾小球细胞的增殖情况，Western blot 方法检测NOX4蛋白表达情况。HE、Masson染色显示NZBWF1小鼠8周即可出现少量间质纤维化，12周及16周时纤维化进一步加重。NZBWF1小鼠8周时系膜细胞数增多，12周和16周时更加明显。NOX4蛋白表达也随着纤维化程度加重而逐渐增加。研究结果提示肾小球系膜细胞及ROS参与了狼疮肾的纤维化过程。通过上述研究了解了狼疮肾纤维化的机制，明确了肾小球系膜细胞和ROS在狼疮肾小球纤维化中的作用，在临床中可能通过检测系膜细胞和ROS的表达情况就能初步了解狼肾的纤维化情况，给临床提供早期诊断的可靠依据，并且通过了解系膜细胞和ROS参与肾纤维化的机制，可以有针对性的设计靶向药物阻断以致逆转纤维化从而达到提高治疗效果改善预后的目的。