Glycolysis Drives TLR Ligand-Induced Maturation and Immune Activation of Liver Sinusoidal Endothelial Cells.

BACKGROUND AND AIMS: Liver sinusoidal endothelial cells (LSECs) are liver-resident antigen-presenting cells that induce immune tolerance, a feature exploited by persistent viruses. Toll-like receptor (TLR) ligands can override this tolerance, but whether metabolic reprogramming underlies LSEC activation remains unknown. We investigated whether TLR ligand-induced functional changes in LSECs require glycolysis and explored the underlying mechanisms.

METHODS

LSECs from wild-type and chronic hepatitis B virus (HBV) replication mice were stimulated with TLR2 ligand P3C or TLR9 ligand ODN1826. LSEC maturation, cytokine production and T cell-priming capacity were assessed. Glycolytic flux was measured by metabolomics and Seahorse analysis. The glycolysis inhibitor 2-deoxy-D-glucose (2-DG) was used, and mTORC1 pathway involvement was examined.

RESULTS

The TLR2 ligand P3C promoted LSEC maturation, while the TLR9 ligand ODN1826 enhanced IL-12 production. Both ligands potentiated LSEC-induced T cell responses. In LSECs isolated from a mouse model of chronic HBV replication, P3C and ODN1826 also induced maturation and enhanced T cell-activating capacity, albeit to a weaker extent. Metabolomics and Seahorse analyses revealed that TLR2/9 ligands enhanced glycolysis and oxidative phosphorylation in LSECs, accompanied by activation of the mTORC1/HIF-1α/c-Myc axis. Blocking glycolysis with 2-DG significantly reduced co-stimulatory molecule expression on P3C-stimulated LSECs and IL-12 production by ODN1826-stimulated LSECs in both wild-type and chronic HBV models. Mechanistically, 2-DG suppressed the mTORC1 pathway, thereby attenuating TLR ligand-induced responses.

CONCLUSIONS

TLR ligand-induced activation and pro-inflammatory functions of LSECs critically depend on glycolysis via the mTORC1 signalling pathway. This reveals a key metabolic mechanism underlying LSEC immune regulation during innate stimulation.