Fig. 1

Gut microbiota modulation of antitumor immunity. The gut microbiota is closely associated with antitumor immunity, and gut pathobionts (e.g., ETBF, P. anaerobius, and S. aureus) promote immunosuppression to facilitate the escape of tumor cells from immunosurveillance. These pathogenic bacteria can (1) disrupt the gut barrier to induce inflammation and bacterial invasion; (2) suppress host antitumor immunity to favor tumor cell survival; (3) inhibit the function, differentiation, and maturation of antitumor immune cells (e.g., cytotoxic CD8⁺ T cells and NK cells) with reduced secretion of proinflammatory cytokines; and (4) increase the intratumoral infiltration of immunosuppressive immune cells (e.g., MDSCs and Tregs). In contrast, these protumorigenic and immunosuppressive events are counteracted by beneficial gut commensals (e.g., C. maltaromaticum, A. mucinphila, Lactobacillus, and Bifidobacterium). CTL cytotoxic T lymphocyte. Figure created with BioRender.com