Abstract: TH-PO047
Hypoxic Renal Tubular Epithelial Cell-Derived Exosomes Promoted Peritubular Endothelial Cell Proliferation via Transfer of Vascular Endothelial Growth Factor A in Ischemic Kidney Injury
Session Information
- AKI: Mechanisms - Primary Injury and Repair - I
November 07, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 103 AKI: Mechanisms
Authors
- Zhong, Xin, Zhongda Hospital, Southeast university, Nanjing, China
- Feng, Ye, Zhongda Hospital, Southeast university, Nanjing, China
- Li, Zuolin, Zhongda Hospital, Southeast university, Nanjing, China
- Tang, Tao-Tao, Zhongda Hospital, Southeast university, Nanjing, China
- Liu, Bi-Cheng, Zhongda Hospital, Southeast university, Nanjing, China
- Lv, Linli, Zhongda Hospital, Southeast university, Nanjing, China
Background
Acute kidney injury (AKI) is characterized by substantial injury of renal tubular epithelial cells (TECs) and peritubular capillaries(PTCs) rarefaction. Our previous studies revealed that increasing number of exosomes were secreted by hypoxic TECs during AKI. However, the effect of TECs exosomes on the injury and repair of the closely located PTCs remains unknown.
Methods
Ischemia-reperfusion (I/R) injury mice was established and sacrificed at Day 1, 3, 7. Tie2-GFP mice were treated with exosomes purified from hypoxia TECs labled with DII fluorescent via the renal parenchymainjection to track exosomes internalized by PTCs. In vitro, exosomes released by HK-2 were applied to HUVEC or a transwell co-culture system was conducted. Exosome secretion was inhibited by knockdown of Rab27a in vivo through lentiviral shRNA administration in I/R mice.
Results
Histologically, tubulointerstitial inflamation and microvascular rarefaction were observed in I/R treated kidneys at Day 3, 7. Tubular injury marker KIM-1, and kidney VCAM-1, ICAM-1 mRNA was induced significantly compared to sham mice. Increasing proliferation of TECs and PTCs were observed by PCNA staining. TEM and NTA showed typical morphology and size of exosome structures purified from TECs. WB showed the expression of exosome markers, Alix and CD63. In vivo, DII labeled TECs exosomes were readily detected in glomerular and PTCs in Tie2-GFR mice. Besides, Knockdown of Rab27a reduced PTCs proliferation and aggravated PTC rarefaction after ischemic injury. In vitro, uptake of exosomes from hypoxia-treated TECs markedly enhance endothelial cell proliferation.Interestingly, VEGFA was significantly up-regulated in both cellular and exosomes fractions of TECs under hypoxic conditions. Exosomes from HK-2 cells with VEGFA siRNA attenuated cell proliferation induced by exosomes in HUVECs. Transwell co-culture study showed that exosomes travel through membrane and were internalized by HUVEC. Importantly, flow cytometry showed that internalization of exosomes significantly decreased when VEGFR was knock down in Endothelial cells.
Conclusion
Increasing release of exosomes from hypoxia TECs promoted PTCs proliferation via transfer of VEGFA, which may represent a novel protective response through which to ameliorate PTC rarefaction in AKI.