MHC-derived allopeptide activates TCR-biased CD8+ Tregs and suppresses organ rejection
Elodie Picarda, … , Ignacio Anegon, Carole Guillonneau
Elodie Picarda, … , Ignacio Anegon, Carole Guillonneau
Published May 1, 2014
Citation Information: J Clin Invest. 2014;124(6):2497-2512. https://doi.org/10.1172/JCI71533.
View: Text | PDF
Research Article Immunology

MHC-derived allopeptide activates TCR-biased CD8+ Tregs and suppresses organ rejection

Abstract

In a rat heart allograft model, preventing T cell costimulation with CD40Ig leads to indefinite allograft survival, which is mediated by the induction of CD8+CD45RClo regulatory T cells (CD8+CD40Ig Tregs) interacting with plasmacytoid dendritic cells (pDCs). The role of TCR-MHC-peptide interaction in regulating Treg activity remains a topic of debate. Here, we identified a donor MHC class II–derived peptide (Du51) that is recognized by TCR-biased CD8+CD40Ig Tregs and activating CD8+CD40Ig Tregs in both its phenotype and suppression of antidonor alloreactive T cell responses. We generated a labeled tetramer (MHC-I RT1.Aa/Du51) to localize and quantify Du51-specific T cells within rat cardiac allografts and spleen. RT1.Aa/Du51-specific CD8+CD40Ig Tregs were the most suppressive subset of the total Treg population, were essential for in vivo tolerance induction, and expressed a biased, restricted Vβ11-TCR repertoire in the spleen and the graft. Finally, we demonstrated that treatment of transplant recipients with the Du51 peptide resulted in indefinite prolongation of allograft survival. These results show that CD8+CD40Ig Tregs recognize a dominant donor antigen, resulting in TCR repertoire alterations in the graft and periphery. Furthermore, this allopeptide has strong therapeutic activity and highlights the importance of TCR-peptide-MHC interaction for Treg generation and function.

Authors

Elodie Picarda, Séverine Bézie, Vanessa Venturi, Klara Echasserieau, Emmanuel Mérieau, Aurélie Delhumeau, Karine Renaudin, Sophie Brouard, Karine Bernardeau, Ignacio Anegon, Carole Guillonneau

×

Figure 8

Tolerance induction after in vivo peptide Du51 infusion.

Options: View larger image (or click on image) Download as PowerPoint
Tolerance induction after in vivo peptide Du51 infusion. (A) Recipients ...
(A) Recipients were either untreated (n = 9), treated with 5 i.v injections of 0.5 mg peptide (n = 4), or treated with short-term continuous peptide infusion by an i.p mini-osmotic pump delivering either 0.5 mg/day alone (n = 8) or combined with a depleting anti-CD8 mAb (OX8) (n = 6) or an anti-MHC class I mAb (OX18) (n = 5), 1 mg/day in the LEW.1W/LEW.1A (n = 5) or BN/LEW.1A (n = 4) strain combination. **P < 0.01, 0.5 mg/day Du51 versus untreated animals and 0.5 mg/day of control peptide. *P < 0.05, 0.5 mg/day Du51 plus OX8 versus 0.5 mg/day Du51. ***P < 0.001, 1 mg/day Du51 versus untreated animals. **P < 0.01, 1 mg/day Du51 versus 1 mg/day Du51 in BN/1A. *P < 0.05 1 mg/day Du51 versus 0.5 mg/day Du51. (B) Anatomopatologic analysis of graft for signs of chronic rejection lesions comparing native heart with that of Du51-treated (20.83 μg/hour) long-term surviving recipients. A, adventitia; M, media. (C) IgG, IgG1, IgG2a, or IgG2b alloantibody production was evaluated in naive (n = 3), syngeneic (n = 3), untreated (n = 3), CD40Ig-treated (n = 3), long-term (n = 2), and Du51-treated animals with graft rejection (n = 4) less than 30 days after rejection or more than 120 days after transplantation. Graph represents MFI ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. (D) Splenocytes were recovered after rejection or on day 120 and analyzed by flow cytometry for the absolute number of each subpopulation from naive (n = 12), long-term (n = 2), and Du51-treated recipients with graft rejection (n = 5). (E) Spleens from naive (n = 4), long-term Du51-treated (n = 2), and Du51-treated recipients with graft rejection (n = 4) were incubated with RT1.Aa/Du51 tetramers. Graphs represents the percentage of Tet+ cells among CD8+ Tregs and the absolute number of Tet+ CD8+ Tregs in spleen ± SEM.