Rapamycin-treated human endothelial cells preferentially activate allogeneic regulatory T cells
Chen Wang, … , George Tellides, Jordan S. Pober
Chen Wang, … , George Tellides, Jordan S. Pober
Published March 8, 2013
Citation Information: J Clin Invest. 2013;123(4):1677-1693. https://doi.org/10.1172/JCI66204.
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Rapamycin-treated human endothelial cells preferentially activate allogeneic regulatory T cells

Abstract

Human graft endothelial cells (ECs) can act as antigen-presenting cells to initiate allograft rejection by host memory T cells. Rapamycin, an mTOR inhibitor used clinically to suppress T cell responses, also acts on DCs, rendering them tolerogenic. Here, we report the effects of rapamycin on EC alloimmunogenicity. Compared with mock-treated cells, rapamycin-pretreated human ECs (rapa-ECs) stimulated less proliferation and cytokine secretion from allogeneic CD4+ memory cells, an effect mimicked by shRNA knockdown of mTOR or raptor in ECs. The effects of rapamycin persisted for several days and were linked to upregulation of the inhibitory molecules PD-L1 and PD-L2 on rapa-ECs. Additionally, rapa-ECs produced lower levels of the inflammatory cytokine IL-6. CD4+ memory cells activated by allogeneic rapa-ECs became hyporesponsive to restimulation in an alloantigen-specific manner and contained higher percentages of suppressive CD4+CD25hiCD127loFoxP3+ cells that did not produce effector cytokines. In a human-mouse chimeric model of allograft rejection, rapamycin pretreatment of human arterial allografts increased graft EC expression of PD-L1 and PD-L2 and reduced subsequent infiltration of allogeneic effector T cells into the artery intima and intimal expansion. Preoperative conditioning of allograft ECs with rapamycin could potentially reduce immune-mediated rejection.

Authors

Chen Wang, Tai Yi, Lingfeng Qin, Roberto A. Maldonado, Ulrich H. von Andrian, Sanjay Kulkarni, George Tellides, Jordan S. Pober

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Figure 1

Rapa-ECs poorly stimulate allogeneic memory CD4+ T cells.

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Rapa-ECs poorly stimulate allogeneic memory CD4+ T cells. (A) CD4+ mem...
(A) CD4+ memory cells were cocultured with allogeneic control ECs or rapa-ECs for 72 hours and analyzed by FACS. Freshly isolated T cells were stained and analyzed immediately following isolation. Representative FACS plots are gated on total CD4+ cells. Similar results were seen in 3 independent experiments. (B) Production of IL-2 and IFN-γ by CD4+ memory cells cocultured with allogeneic control ECs or rapa-ECs at 24 hours was assessed by ELISA. Similar results were seen in 3 independent experiments. (C) ECs were treated with the indicated doses of rapamycin (rapa) for 24 or 72 hours and cocultured with CFSE-labeled allogeneic CD4+ memory T cells. Proliferation of T cells was assessed after 7 days via CFSE dilution. (D) ECs were treated with the indicated doses of rapamycin for 72 hours, washed, and maintained up to 7 days (in the absence of drug), then cocultured with CFSE-labeled allogeneic CD4+ memory T cells. T cell proliferation was assessed after 7 days and normalized to vehicle control (0 ng/ml rapa). (E) Control ECs or rapa-ECs were cultured in a Transwell across from cocultures of untreated ECs and CFSE-labeled allogeneic CD4+ memory T cells. Proliferation of CFSE-labeled T cells was assessed after 7 days. Mean ± SEM of triplicate samples is shown from 3 (C) or 2 (D and E) independent experiments. *P < 0.05.