PTEN inhibits IL-2 receptor–mediated expansion of CD4+ CD25+ Tregs
Patrick T. Walsh, … , Wayne W. Hancock, Laurence A. Turka
Patrick T. Walsh, … , Wayne W. Hancock, Laurence A. Turka
Published September 1, 2006
Citation Information: J Clin Invest. 2006;116(9):2521-2531. https://doi.org/10.1172/JCI28057.
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Research Article Immunology

PTEN inhibits IL-2 receptor–mediated expansion of CD4+ CD25+ Tregs

Abstract

One of the greatest barriers against harnessing the potential of CD4+CD25+ Tregs as a cellular immunotherapy is their hypoproliferative phenotype. We have previously shown that the hypoproliferative response of Tregs to IL-2 is associated with defective downstream PI3K signaling. Here, we demonstrate that targeted deletion of the lipid phosphatase PTEN (phosphatase and tensin homolog deleted on chromosome 10) regulates the peripheral homeostasis of Tregs in vivo and allows their expansion ex vivo in response to IL-2 alone. PTEN deficiency does not adversely affect either the thymic development or the function of Tregs, which retain their ability to suppress responder T cells in vitro and prevent colitis in vivo. Conversely, reexpression of PTEN in PTEN-deficient Tregs as well as in activated CD4+ T cells inhibits IL-2–dependent proliferation, confirming PTEN as a negative regulator of IL-2 receptor signaling. These data demonstrate that PTEN regulates the “anergic” response of Tregs to IL-2 in vitro and Treg homeostasis in vivo and indicate that inhibition of PTEN activity may facilitate the expansion of these cells for potential use in cellular immunotherapy.

Authors

Patrick T. Walsh, Jodi L. Buckler, Jidong Zhang, Andrew E. Gelman, Nicole M. Dalton, Devon K. Taylor, Steven J. Bensinger, Wayne W. Hancock, Laurence A. Turka

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Figure 1

Thymic development of CD4+ Foxp3+ Tregs in the absence of PTEN.

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Thymic development of CD4+ Foxp3+ ...
(A) PTEN is expressed at equivalent levels in CD4+CD25– and CD4+CD25+ T cell subsets from normal mice. (B) Specific recombination at the Pten locus in the presence of Cre was shown by PCR amplification of an 849-bp product in genomic DNA isolated from CD4+ T cells from Cre-ve (+/+), Ptenflox/+Cre+ (+/–), and Ptenflox/floxCre+ (–/–) littermates. (C) Expression of PTEN protein in CD4+ T cells isolated as above. β-Actin was used as a loading control. (D) CD4+CD8+ double-positive (DP), CD4+ single-positive (SP), and peripheral CD4+ T cells were isolated by FACS from 3-week-old wild-type and PTEN-ΔT mice. Cells were subsequently lysed and analyzed for expression of PTEN by immunoblotting. (E) T cell–depleted bone marrow cells from wild-type (Thy1.1+) and PTEN-ΔT (Thy1.2+) mice were used to reconstitute lethally irradiated Thy1.1+ hosts. Mice were reconstituted with either 100% wild-type, 100% PTEN-ΔT, or a mixture of 50% each. Thymic regulatory subsets (CD4SP Foxp3+) were analyzed 10 weeks after reconstitution. Data shown are representative of results from 3 chimeric mice per condition.