多发性骨髓瘤（MM）是一种骨髓驻留的血液系统恶性肿瘤。T辅助细胞（Th细胞）在免疫功能失调和骨髓瘤细胞增殖和生存的促进中起着重要作用，但尚未完全阐明。本研究利用单细胞RNA测序技术，比较了3个健康人和10个MM患者骨髓样本中CD4+ T细胞的转录组谱。CD4+ T细胞被分为7个簇。基于生物信息学分析，MM中存在不平衡的Th17-样细胞分化，涉及IL2-STAT5信号通路和转录因子NKFB1、RELA、STAT3和GTF2A2。CD4+ T细胞簇的伪时间轨迹分析进一步揭示了MM中Th17-样细胞向调节性T细胞（Treg细胞）转化增强的情况，其特征是PLAC8、NKFB1、RELA、STAT3和STAT1等基因在发育路径上的表达变化。MM细胞与CD4+ 均分化/最近活化的原始T细胞之间利用CD74-APP的细胞间相互作用减少可能导致Th17-样细胞分化不平衡。同时，我们也发现了Treg细胞和MM细胞在TIGIT-NECTIN3及LGALS9-CD47通路上的检查点。我们的研究揭示了Th17-样细胞分化不平衡模式以及与MM细胞相关的免疫抑制谱，有助于我们对MM中CD4+ T细胞功能的理解。版权所有 © 2023 Elsevier B.V.。保留所有权利。

Multiple myeloma (MM) is a bone marrow resident hematological malignancy. T helper (Th) cells play an essential role in maladjustment of immune function and promotion of myeloma cell proliferation and survival, which has not been fully elucidated. Here, we compared transcriptome profiles of CD4+ T cells in bone marrow samples of 3 healthy individuals and 10 MM patients before and after treatment using single-cell RNA sequencing. CD4+ T cells were divided into 7 clusters. Imbalanced Th17-like cell differentiation was indicated in MM based on bioinformation analyses, which involved IL2-STAT5 pathways and transcription factors NKFB1, RELA, STAT3, and GTF2A2. Pseudotime trajectory analysis of CD4+ T cell clusters further uncovered the enhanced transition of Th17-like to regulatory T (Treg) cells in MM, which was featured by expression changes of PLAC8, NKFB1, RELA, STAT3, and STAT1 along with the developmental path. Reduced cell-cell interaction between MM cells and CD4+ naïve/recently activated naïve T cells via CD74-APP might lead to imbalanced Th17-like cell differentiation. Checkpoints via TIGIT-NECTIN3 and LGALS9-CD47 in Treg and MM cells were also identified. Our study reveals imbalanced differentiation pattern of Th17-like cells and the immunosuppressive profiles in connection with MM cells, which might help to shed light on CD4+ T cell function in MM.Copyright © 2023 Elsevier B.V. All rights reserved.