Centre for Haemato-Oncology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom.
Department of Haemato-Oncology, Barts Health National Health Service (NHS) Trust, London, United Kingdom.
Blood. 2021 Feb 4;137(5):702-717. doi: 10.1182/blood.2020005170.
Gastrointestinal (GI) graft-versus-host disease (GVHD) is a major barrier in allogeneic hematopoietic stem cell transplantation (allo-HSCT). The metabolite retinoic acid (RA) potentiates GI-GVHD in mice via alloreactive T cells expressing the RA receptor-α (RARα), but the role of RA-responsive cells in human GI-GVHD remains undefined. Therefore, we used conventional and novel sequential immunostaining and flow cytometry to scrutinize RA-responsive T cells in tissues and blood of patients who had received allo-HSCT and to characterize the impact of RA on human T-cell alloresponses. Expression of RARα by human mononuclear cells was increased after exposure to RA. RARαhi mononuclear cells were increased in GI-GVHD tissue, contained more cellular RA-binding proteins, localized with tissue damage, and correlated with GVHD severity and mortality. By using a targeted candidate protein approach, we predicted the phenotype of RA-responsive T cells in the context of increased microenvironmental interleukin-23 (IL-23). Sequential immunostaining confirmed the presence of a population of RARαhi CD8 T cells with the predicted phenotype that coexpressed the effector T-cell transcription factor T-bet and the IL-23-specific receptor (IL-23R). These cells were increased in GI- but not skin-GVHD tissues and were also selectively expanded in the blood of patients with GI-GVHD. Finally, functional approaches demonstrated that RA predominantly increased alloreactive GI-tropic RARαhi CD8 effector T cells, including cells with the phenotype identified in vivo. IL-23-rich conditions potentiated this effect by selectively increasing β7 integrin expression on CD8 effector T cells and reducing CD4 T cells with a regulatory cell phenotype. In summary, we have identified a population of RA-responsive effector T cells with a distinctive phenotype that is selectively expanded in human GI-GVHD and that represents a potential new therapeutic target.
胃肠道（GI）移植物抗宿主病（GVHD）是异基因造血干细胞移植（allo-HSCT）的主要障碍。代谢产物视黄酸（RA）通过表达 RA 受体-α（RARα）的同种反应性 T 细胞增强小鼠的 GI-GVHD，但 RA 反应性细胞在人类 GI-GVHD 中的作用仍未确定。因此，我们使用常规和新型连续免疫染色和流式细胞术来仔细研究接受 allo-HSCT 的患者组织和血液中的 RA 反应性 T 细胞，并表征 RA 对人类 T 细胞同种反应的影响。暴露于 RA 后，人单核细胞中 RARα 的表达增加。GI-GVHD 组织中 RARαhi 单核细胞增加，含有更多的细胞 RA 结合蛋白，定位于组织损伤处，与 GVHD 严重程度和死亡率相关。通过使用靶向候选蛋白方法，我们预测了在增加的微环境白细胞介素 23（IL-23）背景下 RA 反应性 T 细胞的表型。连续免疫染色证实存在具有预测表型的 RARαhi CD8 T 细胞群体，该表型共同表达效应 T 细胞转录因子 T-bet 和 IL-23 特异性受体（IL-23R）。这些细胞在 GI-但不在皮肤-GVHD 组织中增加，并且在 GI-GVHD 患者的血液中也被选择性扩增。最后，功能方法表明，RA 主要增加同种反应性 GI 归巢的 RARαhi CD8 效应 T 细胞，包括体内鉴定的表型细胞。富含 IL-23 的条件通过选择性增加 CD8 效应 T 细胞上的β7 整合素表达并减少具有调节细胞表型的 CD4 T 细胞来增强这种作用。总之，我们已经鉴定出一种具有独特表型的 RA 反应性效应 T 细胞群体，该群体在人类 GI-GVHD 中选择性扩增，代表了一个潜在的新治疗靶点。
