外泌体运载microRNA-155介导上皮与间质交流在缺血再灌注肾损伤向慢性化进展中的作用及机制

The mechanisms of acute kidney injury (AKI) progression to chronic kidney disease (CKD) is not fully elucidated. Epithelial–mesenchymal communication (EMC) plays an important role in acute kidney injury (AKI) progression to chronic kidney disease (CKD). A fundamental function of exosome is to mediate intercellular communication by transferring microRNAs to recipient cells as nanovectors. Our previous studies found that the expression of microRNA-155 was up-regulated in renal acute ischemia-reperfusion injury； hypoxia stimulated exosome secretion of renal tubular epithelial cells, which can activate fibroblast proliferation; in addition, inhibition of microRNA-155 expression in exosome retarded fibroblasts proliferation and up-regulated the expression of smad7. Therefore, we hypothesize AKI progression to CKD is promoted by EMC possibly mediated by exosome-delivered microRNA-155. To validate this hypothesis, we will use model of renal acute ischemia-reperfusion injury in mice and hypoxia injury in epithelial cells，to elucidate the role and mechanism of epithelia-mesenchymal communication mediated by exosomes-delivered microRNA-155 on AKI progression to CKD, thus providing targets for prevention and treatment.

急性肾损伤(AKI)向慢性肾脏疾病(CKD)进展的机制仍未完全阐明。上皮与间质交流(EMC)在AKI向CKD进展中发挥重要作用，外泌体(exosome)是细胞交流的主要载体，能够运载microRNA到受体细胞发挥效应。本项目组前期研究发现缺血再灌注损伤肾脏microRNA-155表达显著升高；而且缺氧损伤的肾小管上皮细胞分泌exosome促进成纤维细胞增殖，抑制exosome中microRNA-155表达后成纤维细胞增殖减少，smad7表达上调。由此，本项目提出exosome运载microRNA-155介导EMC靶向smad7促进缺血再灌注后AKI向CKD进展的假说。为验证假说，本项目拟建立缺血再灌注肾损伤模型和肾小管上皮细胞缺氧模型，阐明exosome运载microRNA-155介导EMC在缺血再灌注肾损伤向CKD进展中的作用及机制，为缺血再灌注后AKI向CKD进展提供防治靶点。

急性肾损伤(AKI)向慢性肾脏疾病(CKD)进展的机制仍未完全阐明。上皮与间质交流(EMC)在AKI向CKD进展中发挥重要作用，外泌体(exosome)是细胞交流的主要载体，能够运载microRNA到受体细胞发挥效应。本项目组探讨外泌体运载的microRNA介导细胞交流影响单侧肾缺血再灌注损伤（UIRI）向肾纤维化进展。结果发现UIRI后肾脏组织和缺氧处理后大鼠肾小管上皮细胞（NRK-52E）外泌体分泌显著增加。Rab27a基因敲除或GW4869治疗抑制外泌体分泌可改善UIRI后肾纤维化。缺氧处理NRK-52E分泌的外泌体可激活大鼠肾成纤维细胞 (NRK-49F)。通过Rab27a敲除或GW4869处理抑制缺氧NRK-52E细胞外泌体分泌，从而减少NRK-49F细胞激活。有趣的是，与对照组相比，外泌性miRNA测序分析显示NRK-52E缺氧后miR-150-5p表达增加。抑制缺氧NRK-52E细胞来源外泌体miR-150-5p表达后可抑制NRK-49F细胞活化的能力，尾静脉注射来自缺氧NRK-52E细胞的外泌体可加重UIRI后肾纤维化，抑制miR-150-5p表达的肾小管源性外泌体可减轻UIRI后肾纤维化。此外，肾小管细胞源性外泌体miR-150-5p可负性调节细胞因子信号转导抑制因子1的表达，从而激活成纤维细胞。因此，阻断外泌体miR-150-5p介导的肾小管上皮细胞-成纤维细胞交流可能为防止UIRI进展为肾纤维化提供一个新的治疗靶点。