CCL3-Mediated Inflammatory Reprogramming of the Hepatocellular Carcinoma Microenvironment Enhances Macrophage Antigen Presentation and Adaptive Immune Response (scRNA-Seq)

Hepatocellular carcinoma (HCC) is a major cause of cancer-related mortality worldwide, largely due to its complex and immunosuppressive tumor immune microenvironment (TIME), which significantly impairs the efficacy of conventional therapies and immune checkpoint blockade (ICB). This study investigates the role of C-C motif chemokine ligand 3 (CCL3) in modulating the HCC TIME, focusing on its impact on immune cell recruitment, macrophage-mediated antigen presentation, and the overall antitumor immune response. We analyzed CCL3 expression in human HCC samples and examined its correlation with inflammatory gene signatures and immune cell infiltration. Using high-dimensional single-cell RNA sequencing (scRNA-seq), multiparameter flow cytometry, and multiplex immunofluorescence, we elucidated how CCL3 influences macrophage functionality and T cell activation. In preclinical HCC models and ex vivo tumor fragment assays, we explored the mechanisms by which CCL3 affects macrophage function and its broader implications for antitumor immunity. Our findings reveal that CCL3 effectively recruits immune cells to the HCC TIME, promotes the formation of tertiary lymphoid structures, and enhances macrophage-mediated antigen phagocytosis and presentation, leading to improved T cell effector functions and cytotoxic activity. This research underscores the critical role of CCL3 in reshaping the HCC TIME to enhance antitumor immunity and suggests that targeting CCL3 could be a promising strategy to improve the efficacy of immunotherapy in liver cancer.