Single-cell and functional profiling identifies an IL6-centered immunometabolic communication circuit in multiple myeloma
Multiple myeloma (MM) persists within a specialized bone marrow niche in which malignant plasma cells, immune dysfunction, inflammatory signaling, and metabolic stress reinforce one another. To resolve this ecosystem at compartment-level resolution, we integrated public single-cell RNA sequencing data with pathway scoring, cell-cell communication inference, independent clinical validation, multiplex immunofluorescence, and metabolic perturbation experiments. Analysis of 95,940 bone marrow cells identified 32 annotated populations and revealed broad microenvironmental remodeling in MM, including plasma-cell expansion, altered cytotoxic and dendritic-cell compartments, TAM-associated inflammatory programs, and lineage-specific hematopoietic perturbations. Hallmark pathway analysis identified recurrent immunometabolic programs, including IL6-JAK-STAT3, TNFα-NFκB, mTORC1 signaling, oxidative phosphorylation, unfolded protein response, hypoxia, and checkpoint/exhaustion-associated pathways. CellChat analysis showed disease-associated rewiring of ligand-receptor networks involving malignant plasma cells, TAMs, dendritic cells, and T/NK subsets, with checkpoint-enriched communication and clinically relevant plasma-cell and CD274 survival associations. Serum IL-6 was elevated in an independent clinical validation cohort. Multiplex immunofluorescence confirmed PD-L1-positive plasma cells, C1QA/C1QB/C1QC-positive TAMs expressing LAG3, and CD8-positive/LAG3-positive cytotoxic T cells. Mechanistically, malignant plasma cells showed transcriptional activation of LDH-associated glycolytic/lactate programs and ASCT2/SLC1A5-GLS-linked glutamine-metabolic programs, nominating these pathways as functional vulnerabilities. Accordingly, the LDH inhibitor galloflavin and the ASCT2/SLC1A5 glutamine-transport inhibitor V-9302 suppressed RPMI-8226 viability in dose- and time-dependent manners; their combination produced synergistic anti-myeloma activity supported by Bliss synergy, combination-index analysis, observed-versus-expected inhibition, and apoptosis-related validation. Together, these findings support an IL6-centered immunometabolic communication circuit linking malignant plasma cells, TAMs, and dysfunctional T cells, and identify cooperative glycolytic/lactate and glutamine-dependent metabolic vulnerabilities with therapeutic relevance in MM.