Single-cell Landscape reveals the Immune Heterogeneity of Bone Marrow Involvement in Peripheral T-cell lymphoma

Evaluation of Bone marrow involvement (BMI) in Peripheral T-cell lymphoma (PTCL) patients is essential for determining the prognosis. However, the tumor microenvironment of bone marrow in PTCL patients remains unclear. We collected 11 fresh bone marrow samples from the patients with BMI and performed the scRNA-seq analysis. Based on the scRNA-seq profiles, we found the immune heterogeneity and the genetic variation at single-cell resolution in the different progress of PTCL. For the immune heterogeneity, the main heterogeneity is in the lymphocytes. There were more effector T cells in AITL compared with PTCL-NOS. We also found more inflammatory response and exhausted lymphocyte cells enriched in AITL compare PTCL-NOS. The immune heterogeneity in AITL was also associated with the prognostic relevance after treatment. In the response group with anti-CD30 tharapy, more specific TCR-T cells enriched in the patients with better response. Further analysis showed the RHOA mutation leading the neoantigen was observed. In the response group with Chidamide treatment, the patients with more CD4 regulate cells could get better response. In the progressed group, the early sign of transformation from T cells to B-like cells was found in the progressed group developed into the diffuse large B cell lymphoma. Moreover, the AITL patients with lymphoma-associated hemophagocytic syndrome contain the precursor exhausted cells with the copy number variation in Chr5. Overall, this study is the first single cell landscape depicting the tumor microenvironment heterogeneity in the bone marrow of PTCL. Moreover, it is innovative in applying the scRNA-seq technology to investigate the immune heterogeneity and the genetic variation at single-cell resolution for the different progress in the treatment of AITL.

外周T细胞淋巴瘤（Peripheral T-cell lymphoma, PTCL）患者的骨髓侵犯（Bone marrow involvement, BMI）评估对预后判断至关重要。然而，目前PTCL患者骨髓的肿瘤微环境仍尚不明确。本研究收集11例合并BMI的PTCL患者的新鲜骨髓样本，开展单细胞RNA测序（single-cell RNA sequencing, scRNA-seq）分析。基于scRNA-seq测序图谱，本研究在单细胞分辨率下揭示了PTCL不同进展阶段中的免疫异质性与遗传变异特征。就免疫异质性而言，淋巴细胞亚群是异质性的主要来源：与非特指型外周T细胞淋巴瘤（Peripheral T-cell lymphoma, not otherwise specified, PTCL-NOS）相比，血管免疫母细胞性T细胞淋巴瘤（Angioimmunoblastic T-cell lymphoma, AITL）样本中效应T细胞占比更高。同时，与PTCL-NOS相比，AITL样本中富集了更多炎症反应相关细胞与耗竭性淋巴细胞。AITL的免疫异质性还与患者治疗后的预后相关。在接受抗CD30治疗的应答队列中，治疗应答较佳的患者体内富集了更多特异性TCR-T细胞（TCR-T）。进一步分析显示，可诱导新抗原产生的RHOA突变被检出。在接受西达本胺（Chidamide）治疗的应答队列中，CD4阳性调节性细胞占比更高的患者可获得更佳的治疗应答。在疾病进展队列中，研究人员观察到T细胞向类B细胞转化的早期特征，此类队列中的患者最终可发展为弥漫大B细胞淋巴瘤（Diffuse Large B-cell Lymphoma, DLBCL）。此外，合并淋巴瘤相关噬血细胞综合征（Lymphoma-associated hemophagocytic syndrome, LAHS）的AITL患者体内，存在携带5号染色体（Chromosome 5, Chr5）拷贝数变异的耗竭性前体细胞。综上，本研究首次构建了PTCL患者骨髓肿瘤微环境的单细胞图谱，揭示了其中的异质性特征。此外，本研究创新性地运用scRNA-seq技术，在单细胞分辨率下解析了AITL治疗过程中不同进展阶段的免疫异质性与遗传变异特征。