CD44-mediated copper accumulation drives Ly6C^hi macrophages activation in ulcerative colitis

Ly6C^hi macrophages activation plays a significant role in the progression of inflammation. This study aims to elucidate the role of CD44-mediated copper accumulation in driving Ly6C^hi macrophages activation in ulcerative colitis (UC). We identified Ly6C^hi macrophages and revealed a significant increased proportion in macrophages from scRNA-seq dataset GSE264408. GW2580, which has been validated to effectively suppress the activation of Ly6C^hi macrophages, ameliorated symptoms and pathological features in UC mice. Proteomic analysis revealed elevated CD44 and reduced copper export protein ATP7A expression in the colon of UC mice, with a significant correlation between them. Additionally, copper accumulation was observed in BMDMs-derived Ly6C^hi macrophages. The CD44 monoclonal antibody IM7 substantially reduced copper accumulation, restored ATP7A protein level, decreased ROS level, and suppressed inflammatory activation in Ly6C^hi macrophages. These findings demonstrated that CD44-mediated copper accumulation drives the activation of Ly6C^hi macrophages, representing a critical mechanism in the inflammatory pathogenesis of UC.