Abstract
Myelodysplastic syndromes/tumors (MDS) are a highly heterogeneous group of myeloid malignancies. It has been reported that 1.38%~20% of MDS patients were accompanied by T cell large granulosa lymphocyte proliferation (LGLP) at the initial diagnosis, and is different from that of MDS combined with T-LGLL in mechanism. Komrokji et al. suggested that MDS-LGLP may be a benign expansion phenomenon caused by innate immunity due to tumor cell activation (Komrokji RS, et al. Leukemia, 2020). While enhanced T cytotoxicity inhibits bone marrow hematopoiesis and causes a decrease in normal blood cells, it also shows higher killing activity against tumor cells, suggesting that CTLs play a role in inhibiting malignant clones in early MDS (Tentori CA, et al. Hemasphere, 2024).In this study, we first performed a retrospective analysis of clinical and laboratory data from 22 MDS-LGLP patients and 66 age-, sex-, and diagnosis-matched MDS patients. The results showed that patients in the MDS-LGLP group had better survival outcomes (P=0.02). The Th/Tc, proportion of CD4+ Tcm cells, total NK cells, mature NK cells, pDCs, and mDCs in the MDS-LGLP group was higher respectively (P<0.05, P<0.01, P<0.01, P<0.05, P<0.01, P<0.001). The proportion of Th17 cells, and CD8+ Tcm cells in the MDS group was higher (P<0.05, P<0.05). In terms of cytokine levels, the MDS-LGLP group showed significantly reduced levels of immune suppressive factors associated with immunomodulation and tumor immune escape (IL-10, TGF-β, IL-6; P<0.01, P<0.001, P<0.001). It suggests that the higher overall survival rate of MDS-LGLP patients may be related to the enhanced anti-tumor immune microenvironment.Given that the presence of LGLP may delay the progression of MDS disease, we set to explore the molecular mechanism of MDS-LGLP occurrence at the single-cell sequencing level. We collected bone marrow mononuclear cells from 3 MDS-LGLP and 3 MDS patients for single-cell RNA sequencing (scRNAseq) and analyzed the results, distinguished different cell subsets by cell surface markers, observed the differences in hematopoietic stem/progenitor cells, lymphoid subsets and TCR clones, and tracked the differences in cell differentiation and development. Through cell differentiation trajectory analysis, we found that hematopoietic progenitor cells (HSPCs) of MDS-LGLP patients had lower tumor stem cell characteristics, and early lymphatic cells showed more terminal differentiation characteristics. The KEGG apoptosis-related pathway score of HSPCs in MDS-LGLP patients was higher than that in MDS patients, consistent with the results of cell differentiation trajectory analysis, suggesting that HSPCs of MDS patients had higher tumor stem cell characteristics and apoptosis arrest. Transcriptome combined with V(D)J sequencing showed that the TCR CDR3 distribution of MDS-LGLP and MDS patients was similar, indicating that MDS-LGLP may be a reactive proliferation of T cells under tumor proliferation stimulation, and the TCR cloning pattern of MDS-LGLP showed a significant trend of shifting from polyclonal to oligoclonal.In addition, DEGs analysis of lymphocyte subsets in MDS-LGLP and MDS groups showed that TMSB10 was significantly highly expressed in MDS patients than MDS-LGLP patients, and was widely positively correlated with immunosuppressive genes such as PD-1, TIM-3 (P＜0.001, P＜0.001 respectively). Immune infiltration analysis showed that the expression level of TMSB10 was significantly positively correlated with the degree of CD8+ T cell infiltration (P＜0.05). GSEA analysis showed that high expression of TMSB10 in the MDS group could upregulate NFAT/NF-κB and IL-10 signaling pathways, which has been shown to be closely related to T cell depletion and anti-tumor immune tolerance.In summary, our comprehensive analysis of clinical data, laboratory characteristics and scRNAseq data showed that in MDS-LGLP patients, cytotoxic T lymphocytes and NK cells functions as to recognize and kill tumor cells by self-proliferation, and low expression of TMSB10 in lymphocytes may be a characteristic change marker of the disease state. The reduction of TMSB10 level may improve the immune tolerance status of T cells, enhance anti-tumor immunity, and render these patients a better survival outcomes. Further experiments are underway to fully understand the underlying mechanisms and potential clinical treatments for this disease.
