Epicardial adipose tissue-secreted ANGPTL2 drives obesity-induced atrial fibrosis via the SLIT3/ROBO1 and Wnt5a signaling axes.

BACKGROUND: Obesity-associated atrial fibrosis is a key pathological factor in conditions such as atrial fibrillation. Although epicardial adipose tissue (EAT) expands pathologically in obese individuals, the mechanism by which key signaling molecules drive atrial fibrosis is unclear. MATERIALS AND METHODS: We used high-fat diet (HFD)-induced obese mice and ex vivo atrial cultures treated with EAT-conditioned medium, recombinant ANGPTL2, and neutralizing antibodies. Pathways were analysed by Western blotting, Co-IP, qPCR, staining, and human atrial RNA-seq. Direct interactions were evaluated via HDOCK docking and PLIP profiling. RESULTS: HFD mice exhibited EAT-specific overexpression of angiopoietin-like protein 2 (ANGPTL2) and left atrial fibrosis. Both EAT-conditioned medium and exogenous ANGPTL2 directly induced fibrosis in isolated atria, an effect blocked by ANGPTL2 neutralizing antibodies. Mechanistically, in silico docking predicted a high-confidence ANGPTL2-SLIT3 interaction (binding free energy: -70.66 kcal/mol; confidence score: 0.9925), which was further supported by Co-IP and PLIP analysis revealing a dense interface of four hydrogen bonds, five salt bridges and one π-cation interaction. ANGPTL2 concurrently activated the SLIT3/ROBO1 and Wnt5a signaling pathways. Transcriptomic analysis of human obese atrial tissue revealed significant enrichment of the SLIT3/ROBO1 and Wnt5a pathways. CONCLUSION: This study reveals a novel pathway whereby EAT-derived ANGPTL2 binds directly to SLIT3 in the obese state, thereby synergistically activating the SLIT3/ROBO1 and Wnt5a signaling axes to drive atrial fibrosis progression. This provides a new potential target for preventing and treating obesity-related fibrosis.