SDF-1/CXCR4轴调控的lncRNA在大鼠移植肾纤维化中的作用及机制

Renal allograft fibrosis caused by chronic renal allograft damage is the major reason of late renal allograft loss. However, the cause of renal allograft fibrosis is still unclear and thus treatment is not available. LncRNAs have been reported to play critical regulatory roles in variety of diseases, however few reports have been made for renal allograft fibrosis related lncRNA. We found in a rat renal transplantation model exhibiting acute rejection that, short-term treatment of low-dose immunosuppression in combination with AMD3100, a CXCR4 antagonist results in long-term allograft survival in our previous study. Likewise, we found AMD3100 could decrease allograft fibrosis in chronic allograft damage rat model. We found significant differences between each group of allograft samples in lncRNA+mRNA expression profiles and then pathway enrichment analysis on different expressed mRNA was performed. Based on these differences and our previous studies, we hypothesize that SDF-1/CXCR4 axis might mediate renal allograft fibrosis through regulating the expression of key lncRNA. Therefore, we will make mechanism study in three levels including molecules, cells and animals to verify our proposed scientific hypothesis. Our study will reveal mechanistic details on renal allograft fibrosis caused by chronic allograft damage by altered lncRNA and may lead to novel targets for early diagnosis and treatment of renal allograft fibrosis in future.

慢性移植肾损伤导致的纤维化是移植肾远期失功的最主要原因，但其形成机制仍不清楚，临床缺乏有效防治方法。lncRNA通过调控基因表达与人类多种疾病相关，但与移植肾纤维化相关的lncRNA尚无报道。我们发现大鼠肾移植急排模型中，使用SDF-1/CXCR4轴特异性拮抗剂AMD3100短期联合低剂量免疫抑制剂可使移植肾长期存活。对大鼠慢性移植肾损伤模型的前期研究发现，使用AMD3100可明显减轻移植肾纤维化程度。进一步通过基因芯片筛选获得了与移植肾纤维化相关的lncRNA及mRNA，并对mRNA进行pathway富集分析。基于以上前期研究和预实验结果，我们提出“SDF-1/CXCR4轴通过调控关键lncRNA表达导致大鼠移植肾纤维化”的科学假说。我们将通过建立动物模型，从分子、细胞及动物水平去验证该假说。本研究将从lncRNA这个新视点揭示移植肾纤维化的发生机制，为今后临床早期诊治提供新思路和靶点。

项目背景.慢性移植肾损伤导致的纤维化是移植肾远期失功的最主要原因。我们前期研究发现，在大鼠慢性移植肾损伤模型中，使用SDF-1/CXCR4轴特异性拮抗剂AMD3100可明显减轻移植肾纤维化程度，lncRNA通过调控基因表达与人类多种疾病相关，本实验旨在研究SDF-1/CXCR4轴通过调控关键lncRNA表达导致大鼠移植肾纤维化的作用及机制。.主要研究内容.1.建立大鼠CAD模型，观察AMD3100对大鼠移植肾纤维化和移植肾功能的改善作用。.2.探讨关键LncRNA、CXXC5、Wnt/β-catenin通路和移植肾纤维化的相关性，鉴定关键LncRNA全长，明确其在rRTECs中的表达及亚细胞定位。.3.探讨SDF-1/CXCR4轴与关键LncRNA、CXXC5、Wnt通路间的相关性，明确Wnt通路在SDF-1诱导的EMT中发挥关键作用。.4.探讨CXXC5在移植肾纤维化和Wnt通路激活中的作用机制。.5.探讨关键LncRNA在移植肾纤维化和Wnt通路激活中的作用机制。.重要结果.1.成功建立大鼠CAD模型，观察不同组别处理大鼠的肌酐、移植肾纤维化程度，发现SDF-1/CXCR4轴的激活可促进大鼠CAD的发展，而AMD3100可一定程度上缓解移植肾炎性细胞浸润，延缓移植肾纤维化进展。.2.验证大鼠CAD模型中LOC102551030、CXXC5、Wnt通路和移植肾纤维化的相关性，而AMD3100可通过阻断SDF-1/CXCR4轴来调控下游靶点的表达和通路的激活，来延缓移植肾纤维化进展。.3.证实体外模型中，SDF-1可激活SDF-1/CXCR4通路促进EMT发生，而AMD3100可逆转EMT，且Wnt通路在进程中发挥关键作用，LOC102551030和CXXC5亦参与了EMT进程。.4.证实CXXC5为移植肾纤维化的潜在靶点，其机制涉及抑制Wnt通路的激活。.5.证实LOC102551030为移植肾纤维化的潜在靶点，其机制涉及上调CXXC5的表达和抑制Wnt通路的激活。.科学意义.本课题通过对SDF-1/CXCR4轴调控关键lncRNA表达，导致大鼠移植肾纤维化机制的探究，从lncRNA这一新视点揭示慢性移植肾损伤导致移植肾纤维化的发生机制，为移植肾纤维化早期诊治提供全新的思路和治疗靶点。