Developing Regulatory T Cells as a Cellular Therapy for Inflammatory Bowel Disease

Abstract

Crohn’s disease (CD) is a chronic, currently incurable inflammatory bowel
disease.There remains an unmet need to develop novel therapies, as currently
used medications often fail to induce or maintain long-term remission and may
also be complicated by significant side-effects. CD4+CD25hiCD127loFOXP3+
regulatory T cells (Tregs) modulate immune activation and contribute substantially to peripheral tolerance. Observations from monogenetic disorders in humans and experimental models of colitis in mice suggest that Tregs have a role in modulating intestinal inflammation. Recent clinical trials provide proof of principal that Tregs can be!selected and expanded in vitro under "good manufacturing practice” conditions while retaining their function and are safe when adoptively transferred to humans. This thesis addresses potential barriers to the development of in vitro expanded Tregs as a cell based therapy for CD by showing that it is possible to expand Tregs from the peripheral blood of CD patients. Extending observations made by other investigators, this thesis shows that FACS-sorted CD4+CD25hiCD127loCD45RA+ Treg subset is likely to be the optimum population from which to!expand Tregs in vitro for potential clinical use, based on in vitro suppressive ability, stability of FOXP3 expression and cytokine expression in comparison with Tregs expanded from MACS-enriched CD4+CD25hi or FACS-sorted CD4+CD25hiCD127loCD45RA-subsets. Tregs expanded in vitro from the CD45RA+ Treg subset expres α4β7 integrin and home to human small bowel in a Scid mouse bearing a human small intestinal xenograft. A rapid 7-hour assay of Treg function is validated, in comparison with a "classic” 96-hour CFSE dilution assay, and used to demonstrate that Tregs expanded from the CD45RA+ Treg subset suppress activation
of CD3+ lymphocytes obtained from inflamed CD mucosa and mesenteric lymph
node. Taken together, these observations suggest that! Tregs expanded in vitro from FACS-sorted CD4+CD25hiCD127loCD45RA+ precursors have many characteristics which make them suitable for consideration as a potential cell-based therapy for CD. These findings pave the way for a further development towards a clinical trial of autologous in vitro expanded Tregs for CD.

Date of Award	2014
Original language	English
Awarding Institution	King's College London
Supervisor	Graham Lord (Supervisor), Maria Hernandez Fuentes (Supervisor) & Thomas T Macdonald (Supervisor)