2411-P: Loss of IL-6 Suppresses TNF-α Expression and Activity and Mitigates Hepatic Inflammation in Murine Models

Introduction and Objective: Metabolic-associated steatotic liver disease (MASLD) is an obesity-associated condition marked by hepatic steatosis and chronic inflammatory signalling driven by proinflammatory cytokines, including IL-6 and TNF-α. Although TNF-α is a major mediator of liver inflammation and injury, the mechanisms by which IL-6 regulates TNF-α expression, signaling, and activation remain unclear. Methods: Male C57BL/6J (wild-type; WT) and IL-6 knockout (IL-6KO) mice were fed either a high-fat diet (HFD) or standard chow for 16 weeks. Recombinant mouse IL-6 was administered to IL-6 KO mice to assess rescue of TACE/ADAM17 expression and TNF-α signaling. Metabolic and immunological profiling was done. Analyses were performed using RNA-seq, qRT-PCR, flow-cytometry, IHC, Western blotting, ELISA, and Oil Red O staining. Results: Under high fat diet conditions, IL-6KO mice showed significantly lower systemic and hepatic TNF-α levels, reduced hepatic steatosis, and improved insulin sensitivity relative to WT mice. Hepatic TNF-α signaling was significantly impaired in HFD-fed IL-6KO mice, as evidenced by reduced TNFR1/2 expression and attenuated activation of ERK1/2, MEK1/2, JNK, c-Jun, p38, and NF-κB. Ex-vivo TNF-α stimulation failed to fully activate downstream signaling in liver tissue from IL-6KO mice, confirming impaired TNF-α responsiveness relative to WT mice. Correspondingly, inflammatory outputs including macrophage infiltration and lobular inflammation were attenuated. Hepatic TACE/ADAM17 expression and activity were reduced in IL-6KO mice, while TIMP3 was increased. IL-6 administration restored hepatic TACE/ADAM17 function and reactivated downstream inflammatory signaling. Conclusion: These data indicate that IL-6 plays a critical role in shaping TNF-α pathogenic activity in liver, suggesting that targeting IL-6 signalling may attenuate TNF-α-mediated liver injury in MASLD and steatohepatitis. Disclosure N. Benobaid: None. S. Kochumon: None. F. Bahman: None. S. Shenouda: None. N. Almansour: None. F. Alrashed: None. A. Al Madhoun: None. F. Al-Mulla: None. E. Rosen: Consultant; Ended; Novartis AG. Research Support; Current; Roche Pharmaceuticals, Alnylam Pharmaceuticals, Inc. R. Ahmad: None. Funding Kuwait Foundation for the Advancement of Sciences (KFAS) (RA AM-2023-021)