IL-32 is a stress-responsive node locked in a noncanonical NF-κB inflammatory loop during MASLD to HCC transition
Background Interleukin-32 (IL-32) presents a long-standing paradox in liver disease, with markedly elevated expression in hepatocellular carcinoma (HCC) yet a protective role against hepatic steatosis. The absence of a canonical receptor or defined secretory pathway has obscured its biological function. This study aimed to resolve this paradox by delineating the regulatory mechanisms that govern IL-32 activity during hepatocarcinogenesis. Methods We analyzed two in-house prospective cohorts, including a MASLD cohort and a MASLD-associated HCC cohort, integrating matched transcriptomic and metabolomic data. Targeted lipidomics and multi-omics analyses were combined with single-cell and spatial transcriptomics. Key findings were validated using functional assays and gene perturbation models. Results We identified a disease stage-specific transcriptional switch in which noncanonical NF-κB signaling (NFKB2/RELB) replaces canonical NF-κB as the primary activator of IL-32, forming an auto-amplifying inflammatory loop. This switch is enabled by FOXO1, which acts as a pioneer factor to maintain chromatin accessibility at IL32 and NF-κB loci. Functionally, IL-32 is coupled to lipid metabolism through DGAT2; however, this axis becomes uncoupled in HCC, where DGAT2 loss rewires NF-κB/ERK signaling without recapitulating global metabolic remodeling, thereby sensitizing cells to inflammatory activation. Conclusions These findings resolve the functional paradox of IL-32 by revealing a multi-layered regulatory network that reprograms its activity during liver disease progression, and define IL-32 as a context-dependent integrator of metabolic and inflammatory signaling, whose regulatory network is rewired during hepatocarcinogenesis to promote a sustained pro-inflammatory state. Highlights Noncanonical NF-κB (NFKB2/RELB) drives a self-amplifying IL-32 loop in HCC. FOXO1 licenses this switch by maintaining chromatin accessibility at IL32 and NF-κB loci. IL-32 shifts from a metabolic regulator in MASLD to an inflammatory driver in HCC.