The Role Of VEGF And Flk1 In Aristolochic Acid Nephropathy And The Immune Mediated Mechanism

Objective To explore the role of peritubular capillary cell(PTC) injury in the tubulointerstitial fibrosis in Aristolochic Acid Nephropathy(AAN) by studying VEGF and its receptor Flk1; To observe the expression of CD40 in the process of AAN, which aided us to understand the immunopathologic mechanism and potentially provides a new therapeutic target for the AAN with tubulointerstitial fibrosis.Methods CD1 mice were administered by i.p with AAI ,and sacrificed at day 3,10,21,35, respectively. Samples of kidneys were processed for immunohistochemical stain(IHC) ,western blot assays , Hematoxylineosin stain(HE) and Masson trichrome stain .Results 1.The HE and Masson stain showed that swelling,degeneration and necrosis of tubular epithelial cells occurred at the early stage ,and renal tubule interstitial fibrosis with shrinking and collapse of the tubule presented at the later stage of AAN.Tubulointerstitial infiltrated lymphocytes were found also in fibrosis area. 2.IHC discovered that the expression of both VEGF and Flk1 down-regulated at the day 3 and began to rise from day 10,but permanent lower expression in the area of interstitial fibrosis.Over expression of CD40 appeared from day 3 to day 35 on the renal tubular epithelial cells in the model. 3.The result of western blot: the expression of both CD40 andα-SMA up-regulated significantly in the kidney at every experiment time point.The expression of VEGF down-regulated from the day 3 and began to rise from the day 10,correlated with analysis of IHC.Conclusions 1.AAN model we made manifested by typical tubulointerstitial fibrosis.Up-regulation ofα-SMA in this model showed transition from renal intrinsic cell to smooth muscle type cell which attributed mainly to tubulointerstitial fibrosis formation,although we have not identified which cell type involved in. 2.The down-regulation of VEGF and Flk1in the kidney showed that injury of peritubular capillary participated in the process of AAN with tubulointerstitial fibrosis.It will suggest that VEGF could maintain vascular intergrity and might relieve the tubulointerstitial fibrosis. 3.The up-regulation of CD40 in the tubule interstitial cell indicated that immune mediated mechanism in the AAN. And it provided one possible target for specific immune treatment of tubulointerstitial fibrosis.