Podoplanin negatively regulates CD4+ effector T cell responses
Anneli Peters, … , Estelle Bettelli, Vijay K. Kuchroo
Anneli Peters, … , Estelle Bettelli, Vijay K. Kuchroo
Published November 21, 2014
Citation Information: J Clin Invest. 2015;125(1):129-140. https://doi.org/10.1172/JCI74685.
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Research Article Immunology

Podoplanin negatively regulates CD4+ effector T cell responses

Abstract

Podoplanin (PDPN, also known as Gp38) is highly expressed on the surface of lymphatic endothelial cells, where it regulates development of lymphatic vessels. We have recently observed that PDPN is also expressed on effector T cells that infiltrate target tissues during autoimmune inflammation; however, the function of PDPN in T cells is largely unclear. Here, we demonstrated that global deletion of Pdpn results in exaggerated T cell responses and spontaneous experimental autoimmune encephalomyelitis (EAE) in mice with a susceptible genetic background. In contrast, T cell–specific overexpression of PDPN resulted in profound defects in IL-7–mediated T cell expansion and survival. Consequently, these animals exhibited a more rapid resolution of CNS inflammation, characterized by a reduced effector CD4+ T cell population in the CNS. Mice harboring a T cell–specific deletion of Pdpn developed exacerbated EAE, with increased accumulation of effector CD4+ T cells in the CNS. Transcriptional profiling of naturally occurring PDPN+ effector T cells in the CNS revealed increased expression of other inhibitory receptors, such as Pd1 and Tim3, and decreased expression of prosurvival factors, including Il7ra. Together, our data suggest that PDPN functions as an inhibitory molecule on T cells, thereby promoting tissue tolerance by limiting long-term survival and maintenance of CD4+ effector T cells in target organs.

Authors

Anneli Peters, Patrick R. Burkett, Raymond A. Sobel, Christopher D. Buckley, Steve P. Watson, Estelle Bettelli, Vijay K. Kuchroo

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Figure 3

Overexpression of PDPN limits IL-7–dependent T cell survival.

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Overexpression of PDPN limits IL-7–dependent T cell survival. (A) Spleno...
(A) Splenocytes from WT and PdpnTG mice (line 560) were analyzed for expression of CD44, PDPN, and IL-7Rα on CD4+FOXP3/GFP– T effector cells (Teff) by flow cytometry. Numbers represent the percentage of CD4 T cells. (B) RNA was isolated from CD4+Foxp3.GFP–CD44hi and CD4+Foxp3.GFP–CD44lo T cells sorted from spleens and lymph nodes of naive WT and PdpnTG mice (line 560). Expression of PDPN and IL-7Rα was assessed by quantitative PCR. (C, D, and F) CD4 T cells were purified from Ly5.1 WT and Ly5.2 PdpnTG mice (line 560) and mixed. (C) Cells were cultured in vitro with the indicated concentrations of IL-7, and the percentage of 7AAD– cells at different time points was determined by flow cytometry. (D) Cells were cultured in vitro in the presence of IL-2 (1 ng/ml), IL-7 (1 ng/ml), or IL-15 (10 ng/ml). The ratio of surviving Ly5.1+ WT to Ly5.2+ PdpnTG CD4 T cells after 96 hours was determined by flow cytometry. Data points represent independent replicates. (E) CD4+CD25– T cells sorted from WT and PdpnTG mice (line 560) were cultured in vitro in the presence or absence of anti-CD3. The expression of IL-7Rα on T cells was determined by flow cytometry at the indicated time points. (F) Mixed Ly5.1+ WT and Ly5.2+ PdpnTG (line 560) CD4 T cells were adoptively transferred into CD90.1+ recipients. Twenty-one days after transfer, the frequency of Ly5.1+ WT and Ly5.2+PdpnTG cells among CD90.2+CD4+ cells was determined in the indicated organs. Data shown are representative of at least 2 independent experiments. *P < 0.05, ***P < 0.0001.