Allograft rejection is restrained by short-lived TIM-3+PD-1+Foxp3+ Tregs
Shipra Gupta, Thomas B. Thornley, Wenda Gao, Rafael Larocca, Laurence A. Turka, Vijay K. Kuchroo, Terry B. Strom
Shipra Gupta, Thomas B. Thornley, Wenda Gao, Rafael Larocca, Laurence A. Turka, Vijay K. Kuchroo, Terry B. Strom
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Research Article Immunology

Allograft rejection is restrained by short-lived TIM-3+PD-1+Foxp3+ Tregs

Abstract

Tregs play a pivotal role in inducing and maintaining donor-specific transplant tolerance. The T cell immunoglobulin and mucin domain-3 protein (TIM-3) is expressed on many fully activated effector T cells. Along with program death 1 (PD-1), TIM-3 is used as a marker for exhausted effector T cells, and interaction with its ligand, galectin-9, leads to selective death of TIM-3+ cells. We report herein the presence of a galectin-9–sensitive CD4+FoxP3+TIM-3+ population of T cells, which arose from CD4+FoxP3+TIM-3– proliferating T cells in vitro and in vivo and were often PD-1+. These cells became very prominent among graft-infiltrating Tregs during allograft response. The frequency and number of TIM-3+ Tregs peaked at the time of graft rejection and declined thereafter. Moreover, these cells also arise in a tolerance-promoting donor-specific transfusion model, representing a pool of proliferating, donor-specific Tregs. Compared with TIM-3– Tregs, TIM-3+ Tregs, which are often PD-1+ as well, exhibited higher in vitro effector function and more robust expression of CD25, CD39, CD73, CTLA-4, IL-10, and TGF-β but not galectin-9. However, these TIM-3+ Tregs did not flourish when passively transferred to newly transplanted hosts. These data suggest that a heretofore unrecognized graft-infiltrating, short-lived subset of Tregs can restrain rejection.

Authors

Shipra Gupta, Thomas B. Thornley, Wenda Gao, Rafael Larocca, Laurence A. Turka, Vijay K. Kuchroo, Terry B. Strom

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Figure 1

The number of CD4+FoxP3+TIM-3+ T cells within dLNs and spleens arising during the allograft response peak at graft rejection.

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The number of CD4+FoxP3+TIM-3+ T cells within dLNs and spleens arising d...
Fully allogeneic BALB/c (H-2d) or syngeneic C57BL/6 (H-2b) full-thickness body skin was grafted on the lateral thorax of FoxP3 GFP-KI reporter C57BL/6 (H-2b) mice. C57BL/6-KI mice reject the BALB/c skin graft on day 7. The number of FoxP3-GFP+TIM-3+ cells in (A) dLNs and (B) spleens from skin transplant recipients was determined by flow cytometry (n ≥ 8 mice). (A and B) The TIM-3+FoxP3+ T cells within dLNs and spleens peaked at the time of rejection and were more numerous in allogeneic as compared with syngeneic grafted hosts. Data are presented as mean ± SEM; *P < 0.05; **P < 0.01. (C) Gated CD4+GFP+FoxP3+ cells harvested from collagenase digested allogeneic skin transplants were analyzed for TIM-3 expression by flow cytometry. CD4+GFP+FoxP3+TIM-3+ Tregs comprised 40% of the graft-infiltrating Tregs on day 5 after transplantation. (D) The magnitude of TIM-3 expression on the TIM-3+ Tregs is depicted in comparison to the staining control. Gray shading represents fluorescence minus 1 for TIM-3 staining, and the black line represents TIM-3 expression on CD4+GFP+FoxP3+ cells in the graft (n = 4).