HBV induces immunosuppressive macrophages via metabolic and epigenetic reprogramming to facilitate the establishment of chronic persistent infection.

BACKGROUND: Hepatitis B virus (HBV) induces hepatic immunosuppressive macrophages to facilitate chronic infection but the mechanisms remain unclear. Metabolic and epigenetic reprogramming during monocyte differentiation into macrophages has also been observed in bacterial infection and Bacillus Calmette-Guerin (BCG) vaccination, shaping tolerant or trained macrophages. OBJECTIVE: To investigate whether HBV modulates monocyte-to-macrophage differentiation via metabolic-epigenetic reprogramming. DESIGN: Monocytes from chronic HBV-infected patients, healthy controls and cord blood were differentiated into macrophages (monocyte-derived macrophages and cord blood monocyte-derived macrophages). Cytokine expression and secretion, metabolic and epigenetic changes and immunomodulatory functions were characterised by qRT-PCR, ELISA, Western blotting, immunofluorescence, multiplexed immunohistochemistry, immunoprecipitation, metabolite measurements, ChIP-seq, ChIP-qPCR assay, plasmid transfection, reanalysed scRNA-seq and flow cytometry. RESULTS: MDMs from CHB patients showed higher IL-10 and lower TNF-α than healthy donors ex vivo. HBV employed its surface antigen (HBsAg) to strongly influence cord blood but not adult monocyte differentiation into such an immunosuppressive macrophage in vitro. This occurred via post-translational modification of histone H3 on residue K18 (H3K18). HBsAg-pyruvate kinase M2 (PKM2) dimer interaction promoted PKM2/LDHA-driven lactate production, enhancing H3K18 lactylation at the IL-10 promoter and increasing IL-10 secretion. Meanwhile, phosphorylation of STAT1 is shifted with increased serine 727-phosphate but decreased tyrosine 701-phosphate via the p38/AKT pathway. It triggers the CD38/NAD+/SIRT1 axis, reducing H3K18 acetylation at the TNF-α promoter and suppressing TNF-α synthesis. Moreover, HBV-educated immunosuppressive macrophages inhibited NK cell IFN-γ production and promoted HBV replication in hepatocytes. CONCLUSIONS: HBV controls monocyte-to-macrophage fate via HBsAg-mediated metabolic-epigenetic-immune cascades to facilitate chronic persistent infection. These metabolic-epigenetic axes represent potential therapeutic targets.