Engineered Type-1 Regulatory T Cells as Cellular Therapy for Treatment of Immune Mediated Diseases

Abstract

Abstract Type 1 regulatory cells (Tr1) are a promising cellular product for suppression of effector T cells in immune mediated diseases, including graft-versus-host-disease (GvHD) in allogeneic hematopoietic stem cell transplantation (allo-HSCT) (Roncarolo et al. Immunity 2018). We have developed an in vitro protocol to produce Tr1 cells by lentiviral transduction of the human IL10 with a constitutive promoter into human CD4+ T cells (Locafaro et al. Molecular Therapy 2017). These engineered Tr1 cells, called LV-10, acquire a characteristic Tr1 cytokine profile (IL-10 and IFN-g high, IL-4 low and expression of intracellular perforin and granzyme B). In vitro, LV-10 cells suppress the proliferation of responder CD4+ T cells upon activation by allogeneic dendritic cells. LV-10 cells also degranulate in response to and kill myeloid cells, including myeloid blasts from patients with acute myeloid leukemia, through a granzyme B- and perforin-dependent mechanism. Interestingly, the ability to degranulate and kill myeloid cells is not present when LV-10 are activated and expanded with anti-CD3 and anti-CD28 coated beads, suggesting that signals beyond TCR, CD28, and IL-10 receptor pathway activation are necessary to reprogram LV-10 cells into cytotoxic cells. In vivo, LV-10 cells injected into NSG mice do not induce xeno-GvHD, in contrast to control CD4+ T cells. In addition, LV-10 cells suppress CD4-induced xeno-GvHD and prevent expansion of myeloid leukemic cells. Experiments are ongoing to compare the potency and in vivo survival of allogeneic vs autologous LV-10 cells. These findings demonstrate the promise of using LV-10 to treat immune mediated diseases, including GvHD in AML patients receiving allo-HSCT.