Membrane-bound IL-2 improves the expansion, survival, and phenotype of CAR Tregs and confers resistance to calcineurin inhibitors

Jakob Kremer; Pierre Henschel; Daniel Simon; Tobias Riet; Christine Falk; Matthias Hardtke-Wolenski; Heiner Wedemeyer; Fatih Noyan; Elmar Jaeckel

doi:10.3389/fimmu.2022.1005582

Membrane-bound IL-2 improves the expansion, survival, and phenotype of CAR Tregs and confers resistance to calcineurin inhibitors

Front Immunol. 2022 Dec 23:13:1005582. doi: 10.3389/fimmu.2022.1005582. eCollection 2022.

Authors

Jakob Kremer¹, Pierre Henschel¹, Daniel Simon¹, Tobias Riet^{1

2}, Christine Falk³, Matthias Hardtke-Wolenski^{1

4}, Heiner Wedemeyer¹, Fatih Noyan¹, Elmar Jaeckel^{1

5}

Affiliations

¹ Department of Gastroenterology, Hepatology & Endocrinology, Hannover Medical School, Hannover, Germany.
² Department I of Internal Medicine, Tumor Genetics, University Hospital of Cologne and Center for Molecular Medicine, Cologne (CMMC), University of Cologne, Cologne, Germany.
³ Institute of Transplant Immunology, Hannover Medical School, Hannover, Germany.
⁴ Institute of Medical Microbiology, Essen University Hospital, University Duisburg-Essen, Essen, Germany.
⁵ Department of liver transplantation, Multi Organ Transplant Program, University Health Network, University of Toronto, Toronto, ON, Canada.

Abstract

Background: Regulatory T cells (Tregs) play an important role in the maintenance of immune homeostasis and the establishment of immune tolerance. Since Tregs do not secrete endogenous IL-2, they are especially dependent on external IL-2. IL-2 deficiency leads to lower Treg numbers, instability of the Treg phenotype and loss of immune regulation. After organ transplantation, patients are treated with calcineurin inhibitors (CNIs), which further limits available IL-2. Application of low-dose IL-2 expands Tregs but also activates NK and CD8+ T cells. It was recently shown that graft-specific Tregs recognizing mismatched MHC I molecules via a chimeric antigen receptor were far more potent than polyclonal Tregs in the regulation of immune responses after solid organ transplantation in a humanized mouse model.

Methods: Therefore, our aim was to enhance the function and stability of transferred CAR-Tregs via expression of membrane-associated IL-2 (mbIL-2).

Results: mbIL-2 promoted higher survival, phenotypic stability, and function among CAR-Tregs than observed in clinical trials. The cells were also more stable under inflammatory conditions. In a preclinical humanized mouse model, we demonstrated that mbIL-2 CAR Tregs survive better in the Treg niche than control CAR Tregs and are even resistant to CNI therapy without affecting other Tregs, thus acting mainly in cis.

Discussion: The functional and phenotypic improvements observed after membrane-attached IL-2 expression in CAR-Tregs will be important step for enhancing CAR-Treg therapies currently being tested in clinical trials for use after kidney and liver transplantation as well as in autoimmune diseases.

Keywords: CNI resistance; chimeric antigen receptor (CAR); graft tolerance; regulatory T cells (Treg); transplantation.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Calcineurin Inhibitors / pharmacology
Calcineurin Inhibitors / therapeutic use
Immune Tolerance
Interleukin-2 / metabolism
Mice
Phenotype
Receptors, Chimeric Antigen* / genetics
T-Lymphocytes, Regulatory

Substances

Receptors, Chimeric Antigen
Calcineurin Inhibitors
Interleukin-2

Grants and funding

This work was supported by grants from the Deutsche Forschungsgemeinschaft, SFB/Transregio 127, Project A4, European Union’s Horizon 2020 research and innovation program (825392; RESHAPE consortium) and the Government of Canada’s New Frontiers in Research Fund (NFRF), NFRFT-2020-00787.