CD74 and atrial fibrillation: Combined with the findings that immune cell infiltration (e.g., CD8+ T cells and neutrophils) is significantly increased in AF patients, and the high expression of biomarkers TP53 and MAPKAPK5 shows a strong positive correlation with immune cell infiltration, it is suggested that the APP-CD74 pathway may exacerbate local atrial inflammatory responses by enhancing the “recruitment signals” from endothelial cells to neutrophils, thereby participating in atrial remodeling.