Assistant Professor University of Virginia Charlottesville, Virginia, United States
Disclosure(s):
Hongji Zhang, MD, PhD: No financial relationships to disclose
Introduction/Rationale: 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 (Pad4^fl/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.
