JLacerda Lab, Hematology and Transplantation Immunology, Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal.
Unidade de Citometria de Fluxo, Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal.
Front Immunol. 2019 Mar 6;10:334. doi: 10.3389/fimmu.2019.00334. eCollection 2019.
The success of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in the treatment of hematological malignancies remains hampered by life-threatening chronic graft vs. host disease (cGVHD). Although multifactorial in nature, cGVHD has been associated with imbalances between effector and regulatory T cells (Treg). To further elucidate this issue, we performed a prospective analysis of patients undergoing unrelated donor allo-HSCT after a reduced intensity conditioning (RIC) regimen containing anti-thymocyte globulin (ATG) and the same GVHD prophylaxis, at a single institution. We studied T cell subset homeostasis over a 24-month follow-up after HSCT in a comparative analysis of patients with and without cGVHD. We also quantified naive and memory T cell subsets, proliferation and expression of the apoptosis-related proteins Bcl-2 and CD95. Finally, we assessed thymic function by T cell receptor excision circle (TREC) quantification and T cell receptor (TCR) diversity by TCRVβ spectratyping. While the total number of conventional CD4 (Tcon) and CD8 T cells was similar between patient groups, Treg were decreased in cGVHD patients. Interestingly, we also observed divergent patterns of Naive and Stem Cell Memory (SCM) subset recovery in Treg and Tcon compared to CD8. Patients with cGVHD showed impaired recovery of Naive and SCM Tcon and Treg, but significantly increased frequencies and absolute numbers of Naive and SCM were observed in the CD8 pool. Markedly increased EMRA CD8 T cells were also noted in cGVHD. Taken together, these results suggest that Naive, SCM and EMRA CD8 play a role in the emergence of cGHVD. Reduced Naive and recent thymic emigrant Tcon and Treg in cGVHD was likely due to impaired thymic output, as it was accompanied by decreased CD4 TREC and TCR diversity. On the other hand, CD8 TCR diversity was similar between patient groups. Furthermore, no correlation was observed between CD8 TREC content and Naive CD8 numbers, suggesting limited thymic production of Naive CD8 T cells in patients after transplant, especially in those developing cGVHD. The mechanisms behind the opposing patterns of CD4 and CD8 subset cell recovery in cGVHD remain elusive, but may be linked to thymic damage associated with the conditioning regimen and/or acute GVHD.
同种异体造血干细胞移植（allo-HSCT）在治疗血液系统恶性肿瘤方面的成功仍然受到危及生命的慢性移植物抗宿主病（cGVHD）的阻碍。虽然 cGVHD 本质上是多因素的，但它与效应和调节性 T 细胞（Treg）之间的失衡有关。为了进一步阐明这个问题，我们在一家机构对接受含抗胸腺细胞球蛋白（ATG）的减强度调理（RIC）方案的无关供体 allo-HSCT 后的患者进行了前瞻性分析，并进行了相同的 GVHD 预防。我们在 cGVHD 患者和无 cGVHD 患者的比较分析中，研究了 HSCT 后 24 个月的 T 细胞亚群稳态。我们还量化了幼稚和记忆 T 细胞亚群、增殖和凋亡相关蛋白 Bcl-2 和 CD95 的表达。最后，我们通过 T 细胞受体切除环（TREC）量化评估了胸腺功能，并通过 TCRVβ 谱分析评估了 TCR 多样性。虽然两组患者的常规 CD4（Tcon）和 CD8 T 细胞总数相似，但 cGVHD 患者的 Treg 减少。有趣的是，我们还观察到与 CD8 相比，Treg 和 Tcon 中幼稚和干细胞记忆（SCM）亚群恢复的模式不同。cGVHD 患者幼稚和 SCM Tcon 和 Treg 的恢复受损，但在 CD8 池中观察到明显增加的幼稚和 SCM 的频率和绝对数量。在 cGVHD 中也观察到明显增加的 EMRA CD8 T 细胞。总的来说，这些结果表明，幼稚、SCM 和 EMRA CD8 在 cGHVD 的出现中起作用。cGVHD 中幼稚、近期胸腺迁出 Tcon 和 Treg 的减少可能是由于胸腺输出受损所致，因为它伴随着 CD4 TREC 和 TCR 多样性的减少。另一方面，两组患者的 CD8 TCR 多样性相似。此外，CD8 TREC 含量与幼稚 CD8 数量之间没有相关性，表明移植后患者的幼稚 CD8 T 细胞的胸腺产生有限，尤其是在发生 cGVHD 的患者中。cGVHD 中 CD4 和 CD8 亚群细胞恢复的相反模式背后的机制仍不清楚，但可能与调理方案和/或急性 GVHD 相关的胸腺损伤有关。
