Fetuin-A increases thrombosis risk in non-alcoholic fatty liver disease by binding to TLR-4 on platelets

Fetuin-A, a liver-derived heterodimeric plasma glycoprotein, exhibits abnormal elevation in non-alcoholic fatty liver disease (NAFLD). Plasma fetuin-A levels correlate closely with both morbidity and mortality associated with cardiovascular diseases. However, the precise influence of fetuin-A on NAFLD-related platelet activation and thrombosis remains to be elucidated.

Fetuin-A directly amplified agonist-induced platelet aggregation, dense granule adenosine triphosphate release, P-selectin exposure, integrin αIIbβ3 activation, spreading, and clot retraction. Mechanistically, fetuin-A bound to platelet Toll-like receptor-4 (TLR-4), activating TLR-4/MyD88, SFK/PI3 K/AKT, cGMP/PKG, and mitogen-activated protein kinase signalling pathways to enhance platelet activation. TLR-4 specific antagonist TAK-242 and TLR-4-deficient mice confirmed the TLR-4 dependence of these effects. Oral administration of firsocostat, rosuvastatin, or pioglitazone demonstrated efficacy in alleviating thrombosis formation in NAFLD mice by reducing fetuin-A levels and attenuating platelet hyperreactivity. Notably, the fetuin-A-inhibiting antibody potently suppressed platelet activation and inhibited thrombosis formation in NAFLD mice. Administration of this antibody attenuated thromboembolism and microvascular thrombosis in NAFLD mice, thereby safeguarding the lung, heart, and brain from exacerbated tissue infarcts. Finally, a positive correlation between plasma fetuin-A concentration and platelet aggregation was observed in NAFLD patients.

Fetuin-A emerges as a positive regulator of platelet hyperreactivity in NAFLD. Acting via TLR-4-dependent signalling pathways, plasma fetuin-A directly amplifies platelet activation and promotes in vivo thrombosis. Firsocostat, rosuvastatin, and pioglitazone abrogate these enhancing effects by reducing fetuin-A levels. The fetuin-A-inhibiting antibody presents potential therapeutic advantages to prevent thrombotic complications in NAFLD.