Exploring the antitumor mechanism of <em>Lactarius hatsudake</em> Tanaka polysaccharides through immune and gut microbiome pathways

<em>Lactarius hatsudake</em> Tanaka is a mushroom recognized for its edible and medicinal properties. Previous research has demonstrated that polysaccharides extracted from <em>Lactarius hatsudake</em> Tanaka (LHP) exhibit direct inhibitory effects on liver cancer cells; however, the <em>in vivo</em> anticancer mechanisms remain inadequately understood. This study aims to further investigate the potential mechanisms of LHP against hepatocarcinoma by analyzing changes in immune response, gut microbiota, and serum metabolites. The results demonstrated that LHP markedly inhibited the growth of liver transplant tumors without inducing toxicity. Histological examination revealed that LHP significantly reversed the splenic index and safeguarded the intestinal mucosa in murine models. Flow cytometric analysis indicated that LHP enhanced the immune response within the tumor microenvironment by augmenting the CD8⁺/CD4⁺ T cell ratio, and forkhead box Protein 3 and interferon-gamma levels in both blood and tumor tissues. Additionally, microbiome analysis indicated that LHP positively modulated the gut microbial community structure, notably increasing the abundance of beneficial bacteria such as <em>norank_f_Muribaculaceae</em>, <em>Dubosiella</em>,<em> Desulfovibrio</em>, and <em>Akkermansia</em>, and suppressing the abundance of<em> Helicobacter</em>. Serum metabolome analysis revealed that LHP significantly up-regulated 16 metabolites and down-regulated 23 metabolites, predominantly through the modulation of lipid metabolic pathways. These results suggest that LHP has the potential to inhibit hepatocellular carcinoma growth by influencing tumor immunity and gut microbiota. These findings offer a theoretical basis for applying LHP in cancer-related foods and pharmaceuticals and propose novel approaches for utilizing natural resources in drug development and health promotion.