基于代谢酶与转运体Oct2-DDAH1-Mate1/Oatp4c1通路的尿毒素ADMA肾脏清除机制研究

尿毒素堆积引起的慢性肾衰已成为严重危害人类健康的重大疾病之一，除透析外尚无有效治疗手段。蛋白结合尿毒素(以不对称二甲基精氨酸ADMA为典型代表)是尿毒素中毒性最强的物质，故聚焦其肾脏清除机制，找寻关键干预策略和治疗靶点，显得十分迫切和必要。已有文献报道肾脏中的代谢酶DDAH1与转运体Oct2、Mate1、Oatp4c1可能参与了ADMA的清除过程。我们前期的研究也证实，促进肾衰大鼠Oct2、DDAH1、Mate1表达或下调Oatp4c1表达均能显著降低ADMA并降低肾损伤标志物Cys-C和KIM-1水平。故推测可通过激活Oct2/Mate1/DDAH1的转运和代谢或抑制Oatp4c1摄取，能减轻肾脏对ADMA的超负荷，改善肾间质微环境，从而有助于肾功能的恢复。本课题拟在上述试验的基础上，利用细胞和分子生物学技术进一步探究ADMA的肾清除机制，为慢性肾衰的临床治疗与新药研发提供一种新的思路。

Chronic kidney disease (CKD) has become one of the critical public health problems because of high incidence and prevalence rate. With progression of CKD, various uremic toxins accumulate, causing chronic renal damage and cardiovascular complications. Uremic toxin asymmetric dimethylarginine (ADMA) is a protein-bound compound of high toxicity. It is prone to accumulate in the renal interstitium, but hard to be excreted. Recent studies have indicated that Oct2、DDAH1、Mate1 and Oatp4c1 play an important role in renal excretion and metabolism of ADMA. Our preliminary data has also demonstrated that: Up-regulation of Oct2, DDAH1, Mate1 and down-regulation of Oap4c1 mRNA can dramatically decrease the level of circulating ADMA, renal injury markers Cys-C and KIM-1 in the rat model of chronic renal failure. We therefore hypothesize that overloaded uremic toxins can be relieved and renal interstitial microenvironment can be improved through activation of Oct2/mate1/DDAH1 mediated transport and metabolism, together with inhibition re-absorption of Oatp4c1. To do so, We will conduct studies focused on ADMA renal uptake, metabolism, efflux and re-absorption. Various in vitro models including renal tubular epithelial cells, isolated perfused kidney, renal slices, and chronic rat renal failure model will be used. Methods such as renal microdialysis, western blot, RT-PCR and LC-MS/MS will also be applied. These experiments will allow us to understand the mechanistic basis of ADMA renal excretion. This study will provide new scientific bases for renal protection effect of facilitating the excretion of uremic toxin ADMA in patients with CKD. It could also bring a new therapeutic modality in the prevention and treatment of CKD as well as new insights into new drug development.