Journal Article

EZH2 identifies the precursors of human natural killer cells with trained immunity

2021

Overview

Objective: Trained immunity of natural killer (NK) cells has shown great potential in the treatment of cancers by eliciting enhancedeffector responses to restimulation by cytokines or cancer cells for long time periods after preactivation. However, the human NKcells responsible for the generation and maintenance of trained immunity are largely unknown. We hypothesized that heterogeneoushuman NK cells would respond differentially to stimulation with a combination of IL-12, IL-15, and IL-18, and that an NK cell subsetmight exist that is mainly responsible for the induction of trained immunity. On the basis of our hypothesis, we aimed to identify thesubset from which cytokine-trained human NK cells originate and to explore possible regulatory targets for drug intervention. Methods: Flow cytometry assays were performed to analyze the functions of cytokine-trained NK cells and examine cell divisionand protein expression in NK cell subsets. Single-cell RNA sequencing (scRNA-seq) plus TotalSeq™ technology was used to track theheterogeneity of NK cells during the induction of trained immunity. Results: Traditional developmental markers for peripheral NK cells were unable to identify the precursors of human NK cells withtrained immunity. Therefore, we used scRNA-seq plus TotalSeq™ technology to track the heterogeneity of NK cells during theinduction of trained immunity and identified a unique cluster of CD57−NKG2A+EZH2+IFNG+MKI67+IL12R+IL15R+IL18R+ NKcells. Enrichment and pseudotime trajectory analyses suggested that this cluster of NK cells contained the precursor of trainedNK cells. We then used flow cytometry to further investigate the role of EZH2 in trained NK precursors and found that CD57−NKG2A+EZH2+ NK cells had faster cell cycles and an enhanced trained phenotype, and EZH2 inhibition significantly impaired theinduction of trained immunity in NK cells. These results suggested that EZH2 is a unique epigenetic marker of precursors of humanNK cells with trained immunity. Conclusions: Our work revealed human NK heterogeneity in the induction of trained immunity, identified the precursor subset fortrained NK cells, and demonstrated the critical role of EZH2 in the induction of trained immunity in human NK cells.

• Publisher: Chinese Anti-Cancer Association (CACA), Cancer Biology & Medicine
• Subject: CD57 antigen / Cytokines / Epigenetics / Flow cytometry / Interleukin 1 / Interleukin 12 / Interleukin 12 receptors / Interleukin 15 / Interleukin 15 receptors / Interleukin 18 / Interleukin 18 receptors / Natural killer cells / NKG2 antigen / Phenotypes