Developing in vitro expanded CD45RA+ regulatory T cells as an adoptive cell therapy for Crohn's disease

Background and aim Thymus-derived regulatory T cells (T regs ) mediate dominant peripheral tolerance and treat experimental colitis. T regs can be expanded from patient blood and were safely used in recent phase 1 studies in graft versus host disease and type 1 diabetes. T reg cell therapy is also conceptually attractive for Crohn9s disease (CD). However, barriers exist to this approach. The stability of T regs expanded from Crohn9s blood is unknown. The potential for adoptively transferred T regs to express interleukin-17 and exacerbate Crohn9s lesions is of concern. Mucosal T cells are resistant to T reg -mediated suppression in active CD. The capacity for expanded T regs to home to gut and lymphoid tissue is unknown. Methods To define the optimum population for T reg cell therapy in CD, CD4 + CD25 + CD127 lo CD45RA + and CD4 + CD25 + CD127 lo CD45RA − T reg subsets were isolated from patients’ blood and expanded in vitro using a workflow that can be readily transferred to a good manufacturing practice background. Results T regs can be expanded from the blood of patients with CD to potential target dose within 22–24 days. Expanded CD45RA + T regs have an epigenetically stable FOXP3 locus and do not convert to a Th17 phenotype in vitro, in contrast to CD45RA − T regs . CD45RA + T regs highly express α 4 β 7 integrin, CD62L and CC motif receptor 7 (CCR7). CD45RA + T regs also home to human small bowel in a C.B-17 severe combined immune deficiency (SCID) xenotransplant model. Importantly, in vitro expansion enhances the suppressive ability of CD45RA + T regs . These cells also suppress activation of lamina propria and mesenteric lymph node lymphocytes isolated from inflamed Crohn9s mucosa. Conclusions CD4 + CD25 + CD127 lo CD45RA + T regs may be the most appropriate population from which to expand T regs for autologous T reg therapy for CD, paving the way for future clinical trials.