糖基化异常IgA1分子致肾脏血管内皮细胞损伤的机制研究

IgA nephropathy (IgAN)is the most popular glomerularnephritis, and abrrent of glycosylate IgA1 molecular was thought to be the initial pathogenic factor of IgAN. Severe vasculopathy and endotheliocyte injury could be found in IgAN and some of patients with mornal blood pressure. However the pathogenesis of renal vasculopathy in IgAN was not clear. It had been found that the soluble antibody of VEGF (sFlt1) was increased in patients with CKD, which had been found in IgAN patients in our previous study. It has been known that sFlt1 could prevent the protective action of VEGF to endotheliocyte. It had been reported thatthe expression of sFlt1 was induced by proteinase active receptor-2 (PAR-2), and the expression of PAR-2 was regulated by proinflomation factors. Glomerula mesangial cell could express proinflomation factor including TNF-a by the stimulation of abrrent glycosylate IgA1, whether it could induce the disturbance of VEGFR in endotheliocyte was not clear.It was hypothesed by the applicant that abrrent glycosylate IgA1 could stimulate mesangial cell to express proinflomation factor, which could induce the disturbance of VEGFR in endotheliocyte and inturn induce the endotheliocyte injury. These hypothese will be certificated by the in vitro cell models.

IgA肾病是最常见的原发性肾小球肾炎，目前认为IgA1分子糖基化异常是该病发病的始动环节。IgA肾病患者存在严重的肾小血管病变及内皮细胞损伤。我们前期发现IgA肾病患者血清VEGF可溶性抗体sFlt1水平显著升高，但其在IgA肾病中的致病机制尚不明确。既往研究显示糖基化异常IgA1分子刺激肾系膜细胞产生多种炎症因子；蛋白酶激活受体PAR-2激活可使内皮细胞sFlt1表达上调，而PAR-2的激活受炎症因子如TNF-a调控；而且sFlt1可拮抗VEGF导致内皮细胞损伤已在先兆子痫中被证实。基于此申请者提出假设：糖基化异常IgA1分子通过活化系膜细胞产生的炎症因子作用于内皮细胞，导致sFlt1表达上调，造成内皮细胞损伤。本研究将采用前期建立的异常IgA1分子刺激系膜细胞的细胞模型，验证异常IgA1分子通过细胞间交互作用，影响内皮细胞sFlt1表达并导致内皮细胞损伤及肾血管病变可能机制的假说。

本课题组利用糖基化异常的IgA1分子形成的致病性IgA分子复合物刺激系膜细胞后，CXCL1、IL6、IL8及MCP1等因子在IgAN组表达明显高于正常对照组，且CXCL1表达变化最为明显。我们将活化的系膜细胞培养上清体外刺激脐静脉内皮细胞，制备IgA肾病致病性IgA1分子复合物-系膜细胞-内皮细胞损伤的模型，发现被刺激后的内皮细胞大量凋亡，且培养上清的vWF因子表达显著升高，与正常对照相比存在显著性差异，证实致病性IgA分子复合物可以通过活化系膜细胞导致内皮细胞的损伤。我们推测IgA肾病患者循环中的致病性IgA1分子复合物通过诱导系膜细胞分泌炎症介质，作用于肾脏小动脉内皮细胞，导致内皮细胞损伤，从而引起肾小动脉硬化。.本研究并未发现IgA患者血清VEGF/sFlt-1水平与内皮细胞损伤标记vWF的水平有相关性，同时VEGF水平在IgA肾病患者及正常对照间无差异，因此研究者认为VEGF/sFlt-1表达的改变可能并不是导致IgA 肾病血管内皮细胞损伤的重要原因，由此此后的关于 PAR-2在内皮细胞的表达及抑制PAR-2后内皮细胞VEGFR1（sFlt-1）表达变化，及相关的干预研究均未进一步进行。本课题组及时调整研究方向，对IgA肾病患者肾组织进行了补体相关成分在肾脏小动脉内皮细胞表达的研究，获得了初步研究结果。