Nterplay Between VEGF And Nrf2 In The Angiogenesis Of Brain Arteriovenous Malformations

Brain arteriovenous malformations(bAVMs)is a congenital vascular lesion which may lead to serious hemorrhagic stoke in young and children,whih is one of the most common diseases seriously harmful to the health of pepole.However,the pathophysiology of the formation and development of bAVMs is still unclear.It has been reported that venous hypertension was an important event in the pathogenesis of bAVMs,which associated closely with the up-regulation of HIF-1?/VEGF signaling pathway.Besides,nuclear factor erythroid 2-related factor 2(Nrf2)significantly influences angiogenesis,which is realted to VEGF closely.However,the interplay between Nrf2 and VEGF under VH in bAVMs remains unclear.Therefore,our study aimed to investigate the interplay between Nrf2 and VEGF due to VH in bAVMs.Objectives:(1)To investigate the expression of Nrf2-ARE and HIF-1?/VEGF signaling pathway in the rats VH models,and the role of Nrf2 in the activation process.(2)To further testify the existence of Nrf2-VEGF loop in the brain microvessel endothelial cells(BMECs),and the effect of absence of Nrf2 in the migration and vascular tube formation of BMECs.Methods:(1)An experimental rat VH model was induced by left common carotid artery-external jugular vein(CCA-EJV)anastomosis.And the expression of Nrf2 in the cortex and hippocampus was detected by immunochemistry and the activation of Nrf2-ARE and HIF-1?/VEGF signaling pathway was determined by Western Blot and qRT-PCR.Besides,short interfering RNA transfection in vivo was used to clarify the role of Nrf2 in the response to VH.(2)In vitro,primary culture BMECs were isolated from Nrf2-/-and Nrf2+/+ mice,and stimulated by VEGF165 and Nrf2 activator tert-Butylhydroquinone(t-BHQ)respectively.And siRNA against HO-1 and the inhibitor of MEK1/2 activation PD98059 were used in our study.Immunohistochemistry staining,western blot,and Quantitative Real-Time PCR were performed to measure mRNA and protein expression of Nrf2-ARE and HIF-1?/VEGF.(3)Trans-well assay and three dimensional Matrigel assay were used to determined the role of Nrf2 in the migration and vascular tube formation of BMECs.Results:(1)In vivo,VH significantly activated Nrf2 and HIF-1?/VEGF signaling pathway,and loss of Nrf2 strongly abolished this effect.(2)In vitro,VEGF165 activated Nrf2 in an ERK1/2-dependent manner,in turn,up-regulated the expression of VEGF.Besides,tert-Butylhydroquinone(t-BHQ),an activator of Nrf2,elevated VEGF expression via Nrf2/HO-1/HIF-1? pathways.(3)Knockout of Nrf2 significantly inhibited the migration and vascular tube formation of BMECs.Conclusions:Interplay between Nrf2 and VEGF induced by VH play an important role in the pathogenesis of bAVMs,which may partly explain the pathogenic mechanism of bAVMs and be considered as a potential therapeutic target for bAVMs in the future.