Exosomes from high glucose-treated glomerular endothelial cells trigger the epithelial-mesenchymal transition and dysfunction of podocytes

Xiaoming Wu,Yu Tong,Zheji Han,Huimin Yan,Dawei Zou,Xiaolei Wang,Nianxiu Tian,Liping Xu,Wanyu Dang,Liangtao Luo,Yanbin Gao,Zhiyao Zhu

doi:10.1038/s41598-017-09907-6

Abstract

New data indicate that abnormal glomerular endothelial cell (GEC)-podocyte crosstalk plays a critical role in diabetic nephropathy (DN). The aim of our study is to investigate the role of exosomes from high glucose (HG)-treated GECs in the epithelial-mesenchymal transition (EMT) and dysfunction of podocytes. In this study, exosomes were extracted from GEC culture supernatants and podocytes were incubated with the GEC-derived exosomes. Here, we demonstrate that HG induces the endothelial-mesenchymal transition (EndoMT) of GECs and HG-treated cells undergoing the EndoMT secrete more exosomes than normal glucose (NG)-treated GECs. We show that GEC-derived exosomes can be internalized by podocytes and exosomes from HG-treated cells undergoing an EndoMT-like process can trigger the podocyte EMT and barrier dysfunction. Our study reveals that TGF-β1 mRNA is enriched in exosomes from HG-treated GECs and probably mediates the EMT and dysfunction of podocytes. In addition, our experimental results illustrate that canonical Wnt/β-catenin signaling is involved in the exosome-induced podocyte EMT. Our findings suggest the importance of paracrine communication via exosomes between cells undergoing the EndoMT and podocytes for renal fibrosis in DN. Thus, protecting GECs from the EndoMT and inhibiting TGF-β1-containing exosomes release from GECs is necessary to manage renal fibrosis in DN.

Highlights

Diabetic nephropathy (DN), a severe microvascular complication of diabetes, is the leading cause of end-stage renal disease (ESRD) worldwide[1]
In our in vitro experiment, glomerular endothelial cell (GEC) were cultured in normal glucose (NG; 5.6 mmol/L glucose +24.5 mmol/L mannitol) or high glucose (HG) conditions (30 mmol/L glucose) for 24 h to examine whether HG induces an endothelialmesenchymal transition (EndoMT)-like process in GECs
The results revealed that nephrin, zonula occludens-1 (ZO-1), Wilms’ tumor 1 (WT 1) expression were remarkably decreased and that α-Smooth Muscle Actin (α-SMA), desmin, and fibroblast-specific protein-1 (FSP-1) expression was significantly increased in podocytes treated with exosomes from HG-treated cells undergoing an EndoMT-like process but not in untreated podocytes or podocytes co-cultured with exosomes from NG-treated GECs (Fig. 4A)

Summary

Introduction

Diabetic nephropathy (DN), a severe microvascular complication of diabetes, is the leading cause of end-stage renal disease (ESRD) worldwide[1]. GEC-podocyte crosstalk has recently been recognized to play a critical role in maintaining the integrity of the glomerular filtration barrier, and alternative GEC-derived secreted factors may profoundly influence the function of podocytes under pathological conditions[14]. Existing studies show that some cell-derived exosomes have the capacity to induce differentiation or transdifferentiation of target cells through the delivery of TGF-β under pathological conditions. Exosomes released from gastric cancer cells can trigger the differentiation of umbilical cord-derived mesenchymal stem cells into carcinoma-associated fibroblasts via the transfer of TGF-β23. We examined whether exosomes released by HG-treated GECs could transmit information to podocytes and induce the EMT and dysfunction of podocytes

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Conclusion