Search

Prevention of allograft rejection often requires lifelong immune suppression, risking broad impairment of host immunity. Nonselective inhibition of host T cell function increases recipient risk of opportunistic infections and secondary malignancies. Here we demonstrate that AJI-100, a dual inhibitor of JAK2 and Aurora kinase A, ameliorates skin graft rejection by human T cells and provides durable allo-inactivation. AJI-100 significantly reduces the frequency of skin-homing CLA(+) donor T cells, limiting allograft invasion and tissue destruction by T effectors. AJI-100 also suppresses pathogenic Th1 and Th17 cells in the spleen yet spares beneficial regulatory T cells (Tregs). We show dual JAK2/Aurora kinase A blockade enhances human type 2 innate lymphoid cell (ILC2) responses, which are capable of tissue repair. ILC2 differentiation mediated by GATA3 requires STAT5 phosphorylation (pSTAT5) but is opposed by STAT3. Further, we demonstrate that Aurora kinase A activation correlates with low pSTAT5 in ILC2s. Importantly, AJI-100 maintains pSTAT5 levels in ILC2s by blocking Aurora kinase A and reduces interference by STAT3. Therefore, combined JAK2/Aurora kinase A inhibition is an innovative strategy to merge immune suppression with tissue repair after transplantation.

Introduction Immune suppressive donor regulatory T cells (Tregs) can be expanded to prevent or treat graft-versus-host disease (GVHD). In human induced Tregs (iTregs), we demonstrated that inhibiting STAT3 phosphorylation (pSTAT3) with S3I-201 increases demethylated Foxp3 and significantly improves their suppressive potency in vitro, mitigating phenotypically plastic iTreg de-differentiation. Objectives To investigate whether human pSTAT3-inhibited iTregs 1) prevent GVHD and 2) maintain donor immunity against leukemia. Methods Our human skin/NSG mouse xenograft model is relevant to GVHD and permits preclinical testing of human pSTAT3-inhibited iTregs in vivo. NSG mice were transplanted with a 1cm2 human skin graft, followed by 5 × 106 allogeneic peripheral blood mononuclear cells with or without 1 × 105 iTregs, dendritic cell-expanded for 5 days with S3I-201 or DMSO. Results We now show human pSTAT3-inhibited iTregs prevent skin graft rejection by alloreactive T cells and spare the anti-leukemia activity of donor cytotoxic T lymphocytes (CTL) (Figure 1A-C). Compared to DMSO-treated iTregs, pSTAT3-inhibited iTregs upregulate skin-homing CLA, as well as immune suppressive IL-9, GARP, and PD-1 (P Conclusion We demonstrate that human pSTAT3-inhibited iTregs can prevent GVHD-mediated tissue damage, preserve anti-leukemia CTL function, and that metabolic reprogramming with coQ10 significantly enhances their suppressive potency. Based upon these data, we will clinically test the safety and efficacy of human pSTAT3-inhibited iTregs in GVHD prevention.