OP0010 Autologous Hematopoietic Stem Cell Transplantation Increases T-Cell PD-1 Expression and Regulatory Mechanisms in Systemic Sclerosis Patients
Authors: L.C.M. Arruda, M.C. Oliveira, D.A. Moraes, D.T. Covas, K.C.R. Malmegrim
Journal: Annals of the Rheumatic Diseases (2015)

<h3>Background</h3> Autologous Hematopoietic Stem Cell Transplantation (AHSCT) has been proved as an alternative for the treatment of severe and progressive systemic sclerosis (SSc) patients [1]. To understand the therapeutic mechanisms enrolled in AHSCT and to further improve its efficacy, we aimed to evaluate the post-transplantation immune reconstitution [2] <h3>Objectives</h3> To evaluate the immune reconstitution after AHSCT through quantification of total, naive and memory CD4<sup>+</sup> T-cells, regulatory T-cells and of exhausted T- and B-cells. <h3>Methods</h3> Peripheral blood was collected from nine diffuse SSc patients before and at 6, 12, 18 and 24 months post-AHSCT. Peripheral blood mononuclear cells were immunophenotyped by flow cytometry. <h3>Results</h3> Total CD3<sup>+</sup>CD4<sup>+</sup> T-cell counts were significantly decreased (<i>P</i>&lt;0.01) from 6-24 months post-AHSCT when compared to baseline due intense depletion of CD4<sup>+</sup>CD45RO<sup>-</sup>CD27<sup>+</sup> naive and CD4<sup>+</sup>CD45RO<sup>+</sup>CD27<sup>+</sup> central-memory cells. No changes were detected in the CD4<sup>+</sup>CD45RO<sup>-</sup>CD27<sup>-</sup> effector or in the CD4<sup>+</sup>CD45RO<sup>+</sup>CD27<sup>-</sup> effector memory T-cell numbers (<i>P</i>&gt;0.05). At the same time, higher counts of CD4<sup>+</sup>CD25<sup>hi</sup>FoxP3<sup>+</sup> regulatory T-cells (Tregs) were observed at 12 months post-AHSCT when compared to baseline (<i>P</i>&lt;0.05), indicating an increasing proportion of Treg/CD3<sup>+</sup>CD4<sup>+</sup> T-cell ratio from 6 months until the end of follow-up (<i>P</i>&lt;0.01). Higher expression (%) of CTLA-4 on CD4<sup>+</sup>CD25<sup>hi</sup> T-cells was observed only at 24 months post-AHSCT (<i>P</i>&lt;0.05), and increasing GITR expression (%) was observed from 6-24 months (<i>P</i>&lt;0.05). PD-1 expression (%) increased at 6 and 12 months post-AHSCT in CD3<sup>+</sup>CD4<sup>+</sup> (<i>P</i>&lt;0.01) and in CD3<sup>+</sup>CD8<sup>+</sup> T-cells (<i>P</i>&lt;0.05) when compared to baseline. No changes were observed in CD19<sup>+</sup> B-cells. <h3>Conclusions</h3> Our results suggest improvement of peripheral immunoregulatory mechanisms and depletion of central memory CD4<sup>+</sup> T-cells after AHSCT, which may contribute to reestablishment of self-tolerance and to control of autoimmunity in SSc patients. <h3>References</h3> van Laar JM, Farge D, Sont JK, Naraghi K, Marjanovic Z, Larghero J, et al. Autologous hematopoietic stem cell transplantation vs intravenous pulse cyclophosphamide in diffuse cutaneous systemic sclerosis: a randomized clinical trial. JAMA. 2014 Jun; 311(24):2490-2498. Baraut J, Grigore EI, Jean-Louis F, Khelifa SH, Durand C, Verrecchia F, et al. Peripheral blood regulatory T cells in patients with diffuse systemic sclerosis (SSc) before and after autologous hematopoietic SCT: a pilot study. Bone Marrow Transplant. 2014 Mar; 49(3):349-354. <h3>Acknowledgements</h3> Funding was provided by CNPq and by the Sao Paulo Research Foundation (FAPESP). <h3>Disclosure of Interest</h3> None declared