TRIM27-controlled endothelium-derived exosomes play a central role in podocyte injury in diabetic kidney disease

Exosomes are extracellular vesicles involved in mediating cell-cell communication by shuttling genetic information and proteins. Here, we investigated whether glomerular endothelial cells-derived exosomes play a central role in mediating podocyte injury and proteinuria formation in diabetic kidney disease and its precise mechanism. In vitro, upon stimulation with high glucose and transforming growth factor-β1, primary human renal glomerular endothelial cells (HRGECs) produced more exosomes that directly mediated podocyte injury. Conversely, pharmacological inhibition of exosome secretion by GW4869, knockdown of tripartite motif-containing 27 (TRIM27) expression, or inhibition of miR-486-5p all abolished the ability of high glucose and transforming growth factor-β1-treated HRGECs to induce podocyte injury. In vivo, injections of HRGEC-derived exosomes aggravated podocyte injury and proteinuria in diabetic mice, which was negated by a miR-486-5p inhibitor. Furthermore, specific knockdown of TRIM27 expression or miR-486-5p in endothelial cells preserved kidney function and attenuated podocyte injury in diabetic mice. Thus, our results suggest that TRIM27-induced glomerular endothelial cell-derived exosomes play a major role in podocyte injury by shuttling miR-486-5p in diabetic kidney disease. Hence, strategies targeting exosomes may be a new direction in developing therapeutics for podocyte injury and proteinuria in diabetic kidney disease.