AUTOPHAGY ATTENUATES RENAL ALLOGRAFT INTERSTITIAL FIBROSIS BY REGULATING THE ENDMT INDUCED BY TNF-A

Kidney interstitial fibrosis is a significant cause of allograft failure in kidney transplantation. Autophagy is a self-digestive process that eliminates impaired or aged proteins and closely related to tissue fibrosis. We previously demonstrated that TNF-α played a critical role in epithelial-mesenchymal transition (EMT) and transplanted kidney fibrosis, Endothelial-to-mesenchymal transition (EndMT) play an important role in kidney fibrosis, however, the effect of TNF-α on EndMT and autophagy in allograft fibrosis has remained unclear. In this study, we first found ultrastructural observations of Chronic allograft dysfunction (CAD) patients’ kidney revealed accumulation of large autophagic vacuoles, expression levels of autophagy-related genes and proteins, LC3 and Beclin-1, were both increased in glomerulus and vascular endothelial cell compared to normal people. Rat renal transplant model was established and intervened with different dose Everolimus, a specific inducer of autophagy, we found same results with human and the progression of EndMT and allograft interstitial fibrosis in low dose Everolimus group was significant reduced. Furthermore, in human umbilical vein endothelial cells (HUVEC) and human arterial endothelial cells (HAEC), Beclin-1, LC3B and Atg-5, were significantly upregulated by TNF-α in a time- and concentration-dependent manner. During this process, the progression of EndMT and fibrosis was dramatically enhanced and when the activity of autophagy was blocked by either 3-MA and CQ, a specific chemical inhibitor of autophagy, or siRNA transfection before TNF-α stimulation, EndMT and fibrosis upregulation. More importantly, Everolimus alleviated the progression of EndMT and allograft interstitial fibrosis in vivo and in vitro by induced autophagy. As a result, we found the dual functions of TNF-α, as an inducer of EndoMT and allograft interstitial fibrosis and an inducer of autophagy through Stat3 signaling pathway. In conclusion, autophagy plays a critical role in the development of EndoMT induced by TNF-α. Autophagy could be suggested as a novel target for the prevention and treatment of renal allograft interstitial fibrosis.