Exosome miRNA-21介导的小管上皮细胞-内皮细胞间对话在肾小管间质炎症形成中的作用研究

Proteinuria is the key factor initiating renal tubulointerstitial inflammation and fibrosis, however, the molecular basis remains unclear. Exosome is circular membrane released by most cell types. The most recent studies indicated that microRNA was present and exert its function within exosome and mediate cellular communication in many diseases. Our previous study found that the abnormal levels of exosome microRNA was closely correlated with renal fibrosis. Previous studies have indicated that endothelial and epithelial cells of the kidney form a complex network of interactions. The hypothesis of this study was: after stimulation with proteinuria, tubular epithelial cell released exosome containing miRNA-21 which subsequently entered endothelial cell and the secreted miR-21 would activate NF-κB of the recipient cell. Through cell culture and animal model experiments, the study propose to demonstrate exosomal miR-21 could activate endothelial cell to initiate tubulointerstitial inflammation. The exploration of this study would provide important theory and experiment basis for treatment of chronic kidney disease.

蛋白尿是肾小管间质炎症和纤维化形成的关键原因，然而，蛋白尿引起肾脏炎症的具体机制仍不十分清楚。Exosome是细胞分泌的囊泡，最近的研究证实其是microRNA存在和行使功能的重要载体，且介导多种疾病发生过程中的细胞间对话。我们既往的研究发现，慢性肾脏病患者exosome内microRNA改变与肾脏纤维化发生密切相关。由于肾小管上皮细胞和内皮细胞紧密联系，其交互作用在炎症放大中可能发挥重要作用。因此，本研究假说为：肾小管上皮细胞受到蛋白尿刺激后，分泌携带miR-21的exosome,与内皮细胞结合后激活内皮细胞NF-κB，导致炎症放大和持续不断。研究拟通过系统的体外细胞培养、模型动物，探讨肾小管上皮细胞exosome miRNA-21介导内皮细胞活化在蛋白尿致肾脏炎症中的作用, 为临床慢性肾脏病防治提供新的理论和实验依据。

肾小管间质炎症是多种急性、慢性肾脏病的共同特征，是导致肾脏疾病进展的关键因素，因此探讨小管间质炎症的发生机制具有十分重要的意义。小管上皮细胞是肾脏的主要细胞结构组分，容易受到缺氧、蛋白负荷毒性的损伤作用，然而小管上皮细胞的损伤信号如何传递到小管间质并不清楚。本研究通过系统的体内、体外研究发现，在蛋白尿情况下，小管上皮细胞分泌exosome增加，并且装配CCL2 mRNA传递到巨噬细胞，促进其炎症表型的活化和巨噬细胞的浸润；而在急性肾脏损伤时，HIF-1α可促进小管上皮细胞分泌富含miRNA-23a的外泌体，并且可以被巨噬细胞摄取，抑制泛素蛋白编辑蛋白A20的活性，诱导巨噬细胞的促炎反应，从而促进小管间质炎症的进展；而缺氧损伤的小管上皮细胞分泌 exosomal miRNA-23a同样可以传递到管周内皮细胞，促进内皮细胞的炎症反应；此外，损伤小管上皮细胞的exosome可在尿液中分离并检测。临床病例研究发现， IgAN患者尿液外泌体及外泌体分泌显著增加，并与蛋白尿及肾小管损伤和肾脏细胞活动性病变密切相关； CCL2 mRNA与肾脏间质炎症、肾功能进展密切相关，可能成为IgAN新型诊断标志物。 因此，本研究揭示了exosome介导的细胞间传递可能是小管间质损伤的新机制，并且可能成为慢性肾脏病诊断的新型标志物，为基于exosome的肾脏病靶点治疗和诊断提供了全新的理论和实验依据。