Ganoderma lucidum
polysaccharide (GLP) is a
prebiotic with immunomodulatory effects. However, the therapeutic potential of GLP in
tumor immunotherapy has not been fully explored, especially in T cell-mediated antitumor immunity. In this study, we found that GLP significantly inhibited
tumor growth and activated antitumor immunity in
colorectal cancer (CRC). In the spleens and
tumor tissues, the proportion of cytotoxic CD8+T cells and Th1 helper cells increased, while immunosuppressive Tregs decreased. Additionally, microbiota
dysbiosis was alleviated by GLP, and
short-chain fatty acid production was increased. Meanwhile, GLP decreased the ratio of
kynurenine and
tryptophan (Kyn/Trp) in the serum, which contributed to antitumor immunity of T cells. More importantly, the combination of GLP and the
immune checkpoint inhibitor anti-PD-1
monoclonal antibody further enhanced the efficacy of anti-PD-1
immunotherapy. Thus, GLP as a
prebiotic has the potential to be used in
tumor immunotherapy.