Pretransplant Short-Term Exposure of Donor Graft Cells to ITK Selective Inhibitor ONO-7790500 Prevents Acute Gvhd in Mouse BMT Model

Abstract

Introduction and Objectives Graft-versus-host disease (GVHD) triggered by activated donor graft cells still remains a major complication and course of non-relapse mortality after HSCT. Interleukin-2-inducible T-cell kinase (ITK) is a TEC family cytoplasmic tyrosine kinase of crucial importance for T cell development and TCR signaling. Recent studies demonstrated that ITK-deficient CD4+ T cells easily differentiated into regulatory T cells (Tregs) and ITK/BTK inhibitor ibrutinib could improve chronic GVHD symptoms in mouse model and human clinical study, suggesting that ITK may have important roles in post-transplant immune tolerance. In this study, we examined the effects of ITK-selective inhibitor (ITKsi; ONO-7790500) on acute GVHD by using murine BMT model. Methods Allogeneic response of ITKsi-treated CD4+ T cells from B6 was evaluated by in vitro system and murine BMT model. In BMT experiments, lethally irradiated 10-week old B6D2F1 recipient mice were transplanted with 5 × 106 TCD BM together with 1.5 × 106 CD4+ T cells from B6 donors. Survival and GVHD severity were clinically monitored, and T cell subset reconstitution and serum cytokine profile were also examined. Results First, to examine the influence of ITKsi on alloreactive T cell to the corresponding antigens in vitro, CD4+ T cells isolated from B6 mice were exposed to ITKsi for 3 hours and then cultured with irradiated Balb/c stimulators. Proliferation and IFN-gamma production of ITKsi-treated T cells in response to allogeneic stimulators were significantly reduced in comparison to those from controls (P Conclusion Taken together, these data showed that pretreatment of CD4+ T cells with ITKsi efficiently regulated alloreactive T cell and improved the symptoms of acute GVHD. ITKsi inhibited both Th1 and Th2 response but spared the expansion of donor-derived Tregs. Our findings suggest that graft manipulation with short-term culture with ITKsi just before transplant could provide a simple but efficient strategy to modulate alloreactive T cell response and clinical GVHD.