Pathogenic Rewiring of IL6 Signaling Fuels Macrophage Immunometabolic reprogramming in COPD

While human genetics implicate the interleukin-6 (IL6) signaling pathway as a potential therapeutic target in chronic obstructive pulmonary disease (COPD), its functional role in pulmonary macrophages remains paradoxical given its established role in promoting cholesterol efflux. Here, integrating single-cell transcriptomics of human COPD lungs with mechanistic studies, we resolve this paradox by identifying a pathogenic rewiring of the IL6/STAT3 pathway. We discovered a disease-enriched macrophage subpopulation exhibiting co-activation of IL6/STAT3 signaling, cholesterol biosynthesis, and inflammatory pathways. In a murine COPD model, chronic cigarette smoke (CS) exposure recapitulated this immunometabolic phenotype. We defined a linear pathway wherein CS-induced IL6 activates STAT3, which directly transactivates the sterol regulatory element-binding protein 2 (SREBP2) to drive de novo cholesterol synthesis. This SREBP2-dependent cholesterol accumulation was essential for NLRP3 inflammasome activation and pro-inflammatory cytokine release. In vitro, pharmacological inhibition of STAT3 or SREBP2, as well as IL6 silencing, disrupted this cascade, suppressing cholesterol-driven inflammation. Critically, in vivo macrophage-specific Il6 knockdown attenuated pulmonary inflammation, cholesterol accumulation, and emphysema development by disrupting the entire IL6/STAT3/SREBP2 axis. Thus, we define the IL6/STAT3/SREBP2 axis as a core immunometabolic driver of COPD pathogenesis, which directly couples CS exposure to sustained macrophage inflammation via pathological cholesterol synthesis, thereby providing a mechanistic basis for targeting this druggable pathway.