Neutrophil Extracellular Traps Prime B Cell—Mediated Fibrogenesis in MASH by Silencing HES1 and Promoting Plasma Cell Differentiation 2261119

Abstract Introduction Metabolic dysfunction—associated steatohepatitis (MASH) is a severe form of metabolic dysfunction—associated steatotic liver disease (MASLD) that can progress to fibrosis, cirrhosis, and hepatocellular carcinoma. Although the FDA-approved Resmetirom shows promise in reversing MASLD, its efficacy in advanced fibrosis remains limited. MASH-fibrosis is difficult to treat partly due to immune microenvironment alterations that sustain inflammation and scarring. B cells have emerged as critical contributors to MASH-fibrosis, yet their mechanisms remain incompletely understood. Here, we investigated how neutrophil extracellular traps (NETs) modulate B-cell function to promote MASH-associated fibrosis. Methods C57BL/6 mice were fed a Western diet (WD) for 40 weeks to induce MASH-fibrosis. NETs were inhibited using neutrophil-specific Pad4 knockout (Pad4fl/fl LysM-Cre) or daily DNase I treatment. Fibrosis was assessed by Sirius Red and Masson staining; cytokines and chemokines were measured by Luminex assays. Hepatic leukocytes were analyzed by scRNA-seq and flow cytometry. Plasma B cells and HES1 expression were evaluated by flow cytometry and in vitro NET stimulation assays. Mature B cells were depleted in vivo using muMT mice. Results WD-induced MASH-fibrosis increased hepatic CD19+CD138+ plasma B cells and suppressed HES1 expression, both reversed by NET inhibition. In vitro, NETs directly suppressed HES1 and promoted plasma-cell differentiation, an effect abolished by DNase I. scRNA-seq revealed broad immune changes across nine hepatic immune cell types, with B cells showing a prominent transcriptomic shift that was normalized by NET inhibition. Both NET blockade and B-cell depletion reduced hepatic fibrosis, inflammation, and cytokine levels. Conclusion NETs promote B-cell—mediated fibrogenesis in MASH by silencing HES1 and driving plasma-cell differentiation. Targeting NET-induced B-cell reprogramming offers a promising therapeutic strategy to limit liver inflammation and fibrosis in MASH. Funding Source n/a Topic Categories Immune Response Regulation: Cellular Mechanisms (IRC)