Characterization of BCR::ABL1-negative NK cells exposed to leukemic microenvironment in a mouse model of Chronic Myeloid Leukemia (https://doi.org/10.1182/bloodadvances.2024014592)

Natural killer (NK) cells play an integral role in immunosurveillance against myeloid malignancies, with their mature phenotype and abundance linked to prolonged treatment-free remission in chronic myeloid leukemia (CML). However, NK cell function is suppressed during the disease, and the orchestrators of this impairment are not fully understood. Using a chimeric BCR::ABL1+ CML mouse model, we characterized the impact of the leukemic microenvironment on NK cell function and gene transcription. To address the latter, we profiled NK cells from spleen and bone marrow of CML and healthy mice by single-cell RNA sequencing. We revealed an inflammatory cytokine response in CML-exposed NK cells, highlighted by the tumor necrosis factor-a (TNFa)-induced gene signature, upregulation of TNFa receptor TNFR2, and enrichment of SOCS family genes such as Cish, the critical NK cell checkpoint. Ex vivo exposure of healthy NK cells to leukemic soluble factors compromised target-specific NK cell degranulation, which was partially rescued by inhibiting Cish or TNFa - candidate targets reveiled by scRNA-seq. In alignment with these findings, NK cells from healthy donors displayed suppressed cytotoxicity when exposed to plasma from untreated CML patients, with a partial restoration upon Cish or TNFa inhibition. Furthermore, NK cells from newly diagnosed CML patients pre-destined for blast crisis showed an enrichment of the TNFa-induced pro-inflammatory gene signature identified in CML mice. These results suggest that targeting inflammatory signaling could enhance NK cell-based immunotherapies for CML.