Session Title: Rheumatoid Arthritis - Human Etiology and Pathogenesis
Session Type: Abstract Submissions (ACR)
Background/Purpose: Treg cell therapy is a promising approach for transplant rejection and severe autoimmunity. Unfortunately, sufficient Treg numbers can be obtained only upon in vitroculture. Functional stability of human expanded (e)Treg and induced (i)Tregs has not been thoroughly addressed for all proposed protocols, hindering clinical translation. We undertook a systematic comparison of eTreg and iTregs to recommend the most suitable protocol for clinical implementation, and then tested its effectiveness and feasibility in autoimmune rheumatological settings with cells from rheumatoid arthritis (RA) patients.
Methods: eTregs were expanded with rapamycin (rapa), while iTregs were induced from naive T cells in the presence of TGF-β with either all-trans retinoic acid (ATRA) or rapa. FOXP3 expression and demethylation, regulatory molecular signature and suppressive function were evaluated after a first round of differentiation and a secondary restimulation deprived of differentiation factors.
Results: Regardless of the protocol, iTregs acquired suppressive functions and FOXP3 expression, but lost them upon withdrawal of differentiation factors. In contrast, rapa eTregs maintained their regulatory properties and retained FOXP3 upon restimulation. Demethylation, but not expression, of FOXP3 predicted Treg functional stability upon secondary TCR engagement in the absence of stabilizing factors. Importantly, Treg expansion with rapa from RA patients produced functionally stable and suppressive Tregs with yields comparable to healthy donors.
Conclusion: Our data indicate ex vivo Treg expansion with rapa as the protocol of choice for clinical application in rheumatological settings, with assessment of FOXP3 demethylation as a necessary quality control step.
J. van Loosdregt,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/ex-vivo-expanded-but-not-in-vitro-induced-human-regulatory-t-cells-are-suitable-for-cell-therapy-in-rheumatological-autoimmune-diseases-thanks-to-stable-foxp3-demethylation/