Single-cell transcriptomics reveals metabolic remodeling and functional specialization in the immune microenvironment of bone tumors

Abstract Objective To investigate the metabolic remodeling and functional specialization of immune cells within the tumor microenvironment (TME) of bone tumors, including Ewing’s sarcoma, osteosarcoma, and giant cell tumor of bone, through high-resolution single-cell RNA sequencing (scRNA-seq) analysis. Methods Immune cells were isolated from 13 bone tumor samples and profiled via scRNA-seq to delineate cellular compositions, metabolic adaptations, and intercellular communication networks. Differential gene expression analysis, metabolic pathway enrichment, and pseudotime trajectory inference were employed to characterize functional states and differentiation processes of immune cell subsets. Results We identified 12 major immune cell clusters with distinct functional and metabolic characteristics. Naïve T cells exhibited amino acid metabolism-dependent activation potential, whereas NK cells relied on lipid metabolism and the TCA cycle for cytotoxic activity. Macrophage subsets demonstrated functional divergence: C06 macrophages adopted lipid metabolism to facilitate immunosuppression and tissue repair, while C04 macrophages displayed pro-inflammatory characteristics associated with complement activation. Intercellular signaling analysis revealed FN1 as a central regulator of immune coordination, governing cell adhesion, migration, and homeostasis within the TME. Conclusion This study provides novel insights into the metabolic and functional plasticity of immune cells in bone tumor TMEs, underscoring the critical role of metabolic remodeling in immune regulation. Our findings highlight potential therapeutic targets for modulating immune cell function and offering new avenues to improve treatment outcomes for patients with bone tumors.