The inhibition of IRE1alpha/XBP1 axis prevents EBV-driven lymphomagenesis in NSG mice

Post-transplant lymphoproliferative disorders (PTLD) are a group of heterogeneous diseases originating in conditions of immune deficiency, whose main driver is considered to be Epstein-Barr virus (EBV). Here, we explored the role of IRE1alpha/XBP1s axis in EBV-driven lymphomagenesis in an NOD SCID gamma mouse model, as these animals develop malignancies that closely resemble PTLD when engrafted with EBV-positive peripheral blood momonuclear cells (PBMC). This study evidences for the first time that 4μ8C IRE1 alpha endoribonuclease inhibitor prevented lymphomagenesis in vivo and B-cell immortalization in vitro driven by the virus. At the molecular level, 4μ8C reduced the expression of EBV antigens such as ZEBRA and LMP1, downregulated c-Myc and cyclin D1, and prevented the activation of STAT3, molecules known to be involved in viral lymphomagenesis. The results obtained in this study suggest that the inhibition of IRE1 alpha endoribonuclease may represent a promising therapeutic strategy to prevent EBV-associated PTLD that arise in immune-deficient patients.IMPORTANCEThe novelty of this study lies in the fact that it shows that IRE1 alpha endoribonuclease inhibition by 4μ8C was able to counteract Epstein-Barr virus-driven lymphomagenesis in NOD SCID gamma mice and prevent B-cell immortalization in vitro, unveiling that this drug may be a promising therapeutic approach to reduce the risk of post-transplant lymphoproliferative disorders (PTLD) onset in immune-deficient patients. This hypothesis is further supported by the fact that 4μ8C impaired the survival of PTLD-like cells derived from mice, meaning that it could be helpful also in the case in which there is the possibility that these malignancies have begun to arise.