Investigating the thymopoiesis stimulating property of interleukin-21 in aging mice

La vaccination est largement utilisée pour la génération de lymphocytes T spécifiques contre les tumeurs. Malheureusement, cette stratégie n'est pas adaptée aux personnes âgées car leur thymus régresse avec l'âge conduisant ainsi à une baisse dans la production de cellules T et à l'accumulation de cellules immunitaires âgées ayant des défauts liés à leurs stimulations. Comme il a été démontré auparavant que L’IL-21 est capable d’induire des fonctions thymiques, nous avons émis l’hypothèse que l’injection d’IL-21 à des souris âgées stimulera la thymopoïèse. Nos résultats montrent que l’administration de l’IL-21 augmente le nombre absolu de thymocytes chez les souris âgées et augmente la migration de ces cellules vers la périphérie ou ils contribuent à la diversité du TCR. De plus les cellules T en périphérie expriment un niveau plus élevé de miR181-a, et par conséquent moins de phosphatase comme SHP2, DUSP5/6 qui inhibent le TCR. En vaccinant des souris âgées avec le peptide Trp2, les souris traitées avec l’IL-21 montrent un retard dans la croissance des cellules B16 tumorales. Cette étude montre que l’IL-21 pourrait être utilisé comme stratégie pour le rétablissement du systeme immunitaire chez les personnes âgées.Vaccines have been largely sought for the generation of protective tumor-specific T cells. Unfortunately however, this strategy is not suitable for the elderly as their thymus regresses with age leading to a decline in T-cell production and accumulation of aged lymphocytes endowed with stimulation-related defects. Interleukin (IL)-21 has been shown to display thymostimulatory properties. Therefore, we hypothesized that IL-21 administration to ageing host may boost T-cell production and restore a competent peripheral T-cell compartment. Our study shows that IL-21 injection to aged mice lead to an increase in the thymocytes absolute number and an increase in thymocytes egress to the periphery where they enhance the T-cell receptor (TCR) diversity. Furthermore T-cell in the periphery express higher level of miR-181a and thus less TCR-inhibiting phosphatases SHP-2 and DUSP5/6 enable them to be more responsive upon stimulation. Consequently, aged rIL-21-treated mice vaccinated using a tyrosinase-related protein 2 (Trp2)-derived peptide exhibited a substantial delay in B16 tumor growth and improved survival. The results of this study highlight the immunorestorative function of rIL-21 paving its use as a strategy for the re-establishment of effective immunity in the elderly

Interleukin-21 promotes thymopoiesis recovery following hematopoietic stem cell transplantation

Abstract Background Impaired T cell reconstitution remains a major deterrent in the field of bone marrow (BM) transplantation (BMT) due to pre-conditioning-induced damages inflicted to the thymi of recipient hosts. Given the previously reported thymo-stimulatory property of interleukin (IL)-21, we reasoned that its use post-BMT could have a profound effect on de novo T cell development. Methods To evaluate the effect of IL-21 on de novo T cell development in vivo, BM derived from RAG2p-GFP mice was transplanted into LP/J mice. Lymphocyte reconstitution was first assessed using a hematological analyzer and a flow cytometer on collected blood samples. Detailed flow cytometry analysis was then performed on the BM, thymus, and spleen of transplanted animals. Finally, the effect of human IL-21 on thymopoiesis was validated in humanized mice. Results Using a major histocompatibility complex (MHC)-matched allogeneic BMT model, we found that IL-21 administration improves immune reconstitution by triggering the proliferation of BM Lin−Sca1+c-kit+ (LSK) subsets. The pharmacological effect of IL-21 also culminates in the recovery of both hematopoietic (thymocytes) and non-hematopoietic (stromal) cells within the thymi of IL-21-treated recipient animals. Although T cells derived from all transplanted groups proliferate, secrete various cytokines, and express granzyme B similarly in response to T cell receptor (TCR) stimulation, full regeneration of peripheral naïve CD4+ and CD8+ T cells and normal TCRvβ distribution could only be detected in IL-21-treated recipient mice. Astonishingly, none of the recipient mice who underwent IL-21 treatment developed graft-versus-host disease (GVHD) in the MHC-matched allogeneic setting while the graft-versus-tumor (GVT) effect was strongly retained. Inhibition of GVHD onset could also be attributed to the enhanced generation of regulatory B cells (B10) observed in the IL-21, but not PBS, recipient mice. We also tested the thymopoiesis-stimulating property of human IL-21 in NSG mice transplanted with cord blood (CB) and found significant improvement in de novo human CD3+ T cell development. Conclusions In sum, our study indicates that IL-21 represents a new class of unforeseen thymopoietin capable of restoring thymic function following BMT

Additional file 1: Figure S1. of Interleukin-21 promotes thymopoiesis recovery following hematopoietic stem cell transplantation

Gating strategies for LSKs. BM cells collected from WT or IL-21R−/− C57BL/6 mice were treated in vitro for proliferation, then stained with the Lin−Sca1+c-kit+ antibody cocktail prior to Ki-67+ incorporation analysis. All described experiments were conducted at least three times with n = 5/group. Figure S2. Functional characterization of T cells. (A) Representative cell trace dilution analysis on CD4+ or CD8+ T cells derived from ctl (unirradiated), PBS-treated, or IL-21-treated LP/J recipient mice. (B) Cytokine quantification by ELISA from T cells derived from the same groups described in panel (A). (C) Representative flow cytometry analysis of granzyme B expression. (D) Quantification of T cells expressing granzyme B. For all presented studies, T cells were stimulated with CD3-CD28 dynabeads for 48 h prior to analyses. All described experiments were conducted at least three times with an n = 5/group. Figure S3. Molecular characterization of T cells. T cells sorted from ctl, PBS-treated, or IL-21-treated LP/J recipient mice were analyzed for their expression of various transcription factors involved in T cell differentiation. All described experiments were conducted at least three times with n = 5/group. Figure S4. Gating strategies for Breg analysis. For detection of IL-10-producing Bregs, CD19+ B cells were first isolated from spleens of treated mice (isotype shown by the filled gray histogram), then stained after in vitro treatment with CD1d and CD5 antibodies. The B cell subset CD1dhiCD5+ was gated prior to IL-10 assessment by intracellular staining. All described experiments were conducted at least three times with n = 5/group. (PDF 2111 kb