CD45 ligation expands Tregs by promoting interactions with DCs
Geoffrey Camirand, … , Christopher E. Rudd, David M. Rothstein
Geoffrey Camirand, … , Christopher E. Rudd, David M. Rothstein
Published September 9, 2014
Citation Information: J Clin Invest. 2014;124(10):4603-4613. https://doi.org/10.1172/JCI74087.
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Research Article Immunology

CD45 ligation expands Tregs by promoting interactions with DCs

Abstract

Regulatory T cells (Tregs), which express CD4 and FOXP3, are critical for modulating the immune response and promoting immune tolerance. Consequently, methods to expand Tregs for therapeutic use are of great interest. While transfer of Tregs after massive ex vivo expansion can be achieved, in vivo expansion of Tregs would be more practical. Here, we demonstrate that targeting the CD45 tyrosine phosphatase with a tolerogenic anti-CD45RB mAb acutely increases Treg numbers in WT mice, even in absence of exogenous antigen. Treg expansion occurred through substantial augmentation of homeostatic proliferation in the preexisting Treg population. Moreover, anti-CD45RB specifically increased Treg proliferation in response to cognate antigen. Compared with conventional T cells, Tregs differentially regulate their conjugation with DCs. Therefore, we determined whether CD45 ligation could alter interactions between Tregs and DCs. Live imaging showed that CD45 ligation specifically reduced Treg motility in an integrin-dependent manner, resulting in enhanced interactions between Tregs and DCs in vivo. Increased conjugate formation, in turn, augmented nuclear translocation of nuclear factor of activated T cells (NFAT) and Treg proliferation. Together, these results demonstrate that Treg peripheral homeostasis can be specifically modulated in vivo to promote Treg expansion and tolerance by increasing conjugation between Tregs and DCs.

Authors

Geoffrey Camirand, Ying Wang, Yuning Lu, Yisong Y. Wan, Yan Lin, Songyan Deng, Galip Guz, David L. Perkins, Patricia W. Finn, Donna L. Farber, Richard A. Flavell, Warren D. Shlomchik, Fadi G. Lakkis, Christopher E. Rudd, David M. Rothstein

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Figure 1

Anti-CD45RB treatment acutely induces FOXP3+ Tregs in the periphery.

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Anti-CD45RB treatment acutely induces FOXP3+ Tregs in the periphery. (A)...
(A) Representative FOXP3, CTLA-4, and CD25 expression on day 10 by flow cytometry on splenic CD4+ T cells from mice that received control IgG, alloantigen (Allo) and control IgG, anti-CD45RB (day –1, 0, and 5), or alloantigen and anti-CD45RB. Numbers represent mean percentage ± SD expression in live CD4+ T cells. *P < 0.05 vs. control IgG, **P < 0.05 vs. alloantigen and control IgG (n = 8–19 mice per group from 4 independent experiments). (B) Number of splenic FOXP3+, CD25+, and CTLA-4+CD4+ cells in each group of mice on day 10 relative to that in naive untreated control mice (n = 3–14 mice per group). *P < 0.05 vs. naive or untreated and alloantigen. (C) Number of FOXP3–CD4+ cells from spleens of mice treated with anti-CD45RB (day 10) relative to that in untreated mice (n = 8–10 mice per group, from 3 independent experiments; NS, not significant). (D) Representative flow cytometry histograms of CD69, CD44, CD62L, and CD45RB expression on FOXP3+ and FOXP3–CD4+ cells from naive and anti-CD45RB–treated mice (day 10). (E) Representative in vitro suppression by Tregs from anti-CD45RB–treated and untreated mice. Sorted CD4+CD25+ cells from naive (untreated) or anti-CD45RB–treated mice (day 10) were cultured in varying numbers with irradiated allogeneic splenocytes (BALB/c stimulators) and naive CD4+CD25– responder cells. Proliferation was assessed after 5 days. n = 4–6 mice per group from 2 independent experiments. No statistical difference between treated and naive mice was observed at any cell ratio.