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 9

Ex vivo expansion of PTEN-ΔT Tregs does not affect their regulatory phenotype.

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Ex vivo expansion of PTEN-ΔT Tregs does not affect their regulatory phen...
(A) Real-time PCR analysis of expression levels of Foxp3 mRNA in PTEN-ΔT CD4+CD25+CD45RBlo cells that have been expanded for 8 days ex vivo with rIL-2 compared with freshly isolated CD4+CD25+CD45RBlo and CD4+CD25–CD45RBhi cells from wild-type littermate mice. Results are representative of 3 independent experiments. LMC, littermate control. (B) Expression of Foxp3 protein on CFSE-labeled PTEN-ΔT CD4+CD25+CD45RBlo cells expanded for 8 days with rIL-2 (100 U/ml). (C) PTEN-ΔT Tregs were expanded in the presence of rIL-2 for 8 days and subsequently washed extensively before coculture at the indicated ratio with wild-type CD4+CD25–CD45RBhi responder cells expressing the Thy1.1 congenic marker. Freshly isolated CD4+CD25+CDRBlo cells from wild-type mice were used for direct comparison. Cells were stimulated in the presence of 3 × 105 irradiated APCs with soluble anti-CD3 (0.5 μg/ml) for 72 hours, at which time CFSE dilution of Thy1.1-expressing responder cells was examined by flow cytometry. 25+:25–, ratio of CD4+CD25+CD45RBlo cells to CD4+CD25–CD45RBhi cells as denoted in the labels to the left of the panels. (D) Quantitative comparison of level of suppression by wild-type and PTEN-ΔT Tregs through calculation of number of mitotic events of Thy1.1+ responder cells.