The distinct characteristic of two peritoneal macrophage subsets in a mouse model of hepatocellular carcinoma presents a novel therapeutic strategy.

The peritoneal cavity (PerC) is a discrete anatomical compartment housing diverse peritoneal macrophage subpopulations. Nonetheless, there exists a paucity of knowledge concerning the distinct functions of these subpopulations in the context of hepatocellular carcinoma (HCC) and their evolution throughout tumor advancement. This investigation seeks to analyze the characteristics of two principal peritoneal macrophage subpopulations, specifically large peritoneal macrophage (LPM) and small peritoneal macrophage (SPM), in the context of HCC. The results of our research indicate a significant decrease in the proportion of LPM during the progression of HCC, accompanied by an increase in the quantity of SPM. Furthermore, SPM found in ascites exhibited a macrophage phenotype that supports tumor growth in HCC. Importantly, the dynamic decrease of LPM in murine models following lipopolysaccharide (LPS) stimulation led to a decrease in survival rate, highlighting the critical role of the altered LPM to SPM ratio in HCC survival. By employing clodronate liposomes (CL) to deplete peritoneal macrophage in murine models, followed by the adoptive transfer of LPM, we effectively prolonged the survival of HCC and attenuated tumor progression. Our results suggest that a decrease in the LPM to SPM ratio correlates with increased mortality in the HCC model. On the contrary, the maintenance of a high ratio of LPM to SPM has shown a positive effect on HCC survival. These findings have enhanced our understanding of the complex interaction between different subpopulations of peritoneal macrophage in the development of HCC. Furthermore, these results have important implications for the development of novel therapeutic strategies.