Mechanisms Of Epstein-barr Virus Nuclear Antigen 1 Induced Tregs Accumulation In NPC

BackgroundEBV,which can be detected in almost all the poorly differentiated or undifferentiated nasopharyngeal squamous cell carcinoma,plays important role in the pathogenesis and progression of NPC.Recent studies demonstrated that EBV infected change immune microenvironment which favors the tumor immune escape.Documented reports proved that EBV infection increased infiltration of Tregs in malignancy.Both natural and induced Tregs increased in EBV-positive Hodgkin lymphoma which recruit Tregs via chemotaixs and conversion.It is reported that EBNA1 specific CD8+ T cell could not killed EBNA1+ tumor cells,and this suggested EBNA1 could induce tumor immune escape.The aim of this study is to demonstrate the mechanisms of EBNA1 accumulated Tregs in NPC.Materials and methodsWe used immunohistochemistry to test EBNA1 and Downstream proteins,establishment stable over-expression EBNA1 NPC cells.We proved over-expressed NPC cells expressed higher levels of TGF-?1 and CCL20.MACS was used to select CD4+CD25 naive T cells and CD4+CD25+ Tregs which used to co-culture with NPC cells.NPC cells co-cultured with monocytes could polarize M2 macrophage,polarized-M2 macrophage could increase percent of Treg.Results(1)Expression of EBNA1 in NPC has a positive correlation with infiltrated Treg cells.(2)TGF-?1 was abundant in EBNA1+ NPC cells,TGF-?1 could induced CD4+CD25-naive T cells transfer into Treg.(3)Enhanced CCL20 production in EBNA1+ NPC cells could chemotaxis Treg.(4)EBNA1+ NPC cells polarized M2 macrophages could increase percent of Treg.ConclusionEBNA1+ NPC cells recruit Treg via:(1)TGF-?1 induced naive T cells transferred into Treg;(2)CCL20 chemotaxis Treg to tumor cells;(3)polarized M2 macrophages induced naive T cells converted into Treg.