TSC22D1 promotes liver sinusoidal endothelial cell dysfunction and induces macrophage M1 polarization in non-alcoholic fatty liver disease.

Background: The progression of non-alcoholic fatty liver disease (NAFLD) to non-alcoholic steatohepatitis (NASH) and liver fibrosis remains poorly understood, though liver sinusoidal endothelial cells (LSECs) are thought to play a central role in disease pathogenesis.

Aim: To investigate the role of TSC22D1 in NAFLD fibrosis through its regulation of LSEC dysfunction and macrophage polarization.

Methods: We analysed single-cell transcriptomic data (GSE129516) from NASH and normal mouse models and identified TSC22D1 as a key regulator in LSECs. In vitro and in vivo experiments were conducted to validate the functional role of TSC22D1. Human LSECs were cultured and transfected to overexpress TSC22D1, and evaluated using flow cytometry, enzyme-linked immunosorbent assay, and quantitative polymerase chain reaction. NAFLD mice were used to assess TSC22D1 expression and its effects on LSEC dysfunction, endothelial-mesenchymal transition (EndMT), and microvascularization.

Results: Single-cell analysis revealed that TSC22D1 mediates intercellular communication between LSECs and macrophages via the tumor necrosis factor-like weak inducer of apoptosis (TWEAK)/fibroblast growth factor-inducible 14 (FN14) signalling pathway, promoting M1 macrophage polarization and exacerbating liver fibrosis. In vitro studies revealed that TSC22D1 overexpression in LSECs exacerbated endothelial dysfunction and M1 polarization, whereas TWEAK inhibition attenuated these effects. Mechanistically, TSC22D1 drives LSEC microvascularization and EndMT through the TWEAK/FN14 pathway, leading to increased secretion of pro-inflammatory cytokines and M1 macrophage polarization. In vivo, experiments demonstrated that TSC22D1 inhibition via adeno-associated virus serotype 8-short hairpin RNA reduced NAFLD progression and liver fibrosis.

Conclusion: Our findings indicate a pivotal role of TSC22D1 in NAFLD fibrosis, demonstrating its dual function in regulating LSEC dysfunction and inflammatory responses. TSC22D1 may be a promising target for the treatment and the prevention and management of NAFLD progression to fibrosis.