Table 1.
The regulatory effects of gut microbiota and its metabolites on tumor immunity.
| Cancer type | Gut microbiota/microbial metabolites | Effects | Mechanisms | References |
|---|---|---|---|---|
| Breast cancer | Commensal microbiota | Induction of antitumor innate immunity | Reduce the abundance of stromal mast cells | (50) |
| Melanoma | Commensal microbiota | Induction of antitumor innate immunity | Induce the expansion of NK cells and Th1 cells and foster their homing to the bone marrow | (51) |
| Human papilloma virus-induced cancer | Lactobacillus casei BL23 | Induction of antitumor innate immunity | Enhance the proliferation and cytotoxic activities of NK cells | (52) |
| Lymphoma | C-di-AMP, Akkermansia muciniphila | Induction of antitumor innate immunity | Facilitate the activation and intratumoral infiltration of NK cells | (53) |
| Colorectal cancer | Bacteroides, Prevotella | Induction of antitumor innate immunity | Inhibit the production of IL-9 and IL-17A | (54) |
| Colorectal cancer | Commensal microbiota | Induction of antitumor innate immunity | Inhibit the production of IL-1β, IL-6 and TNF-α; promote the production of IL-10 and TGF-β; foster Treg cell accumulation | (55) |
| Colorectal cancer | Odoribacter splanchnicus | Induction of antitumor innate immunity | Induce the expansion of Th17 cells and increase the levels of IL-17A and IL-22 | (56) |
| Colorectal cancer | Sodium butyrate | Induction of antitumor innate immunity | Reduce the frequency of Treg cells and increase the frequency of NKT and Th17 cells; promote IL-17 production and suppress IL-10 production | (57) |
| Hepatocellular carcinoma | Lactobacillus reuteri, acetate | Induction of antitumor innate immunity | Inhibit IL-17A expression by ILC3s | (58) |
| Colorectal cancer | Malnutrition-induced gut microbiota dysbiosis | Activation of pro-tumor innate immunity | Facilitate the activation of macrophages | (59) |
| Colorectal cancer | Proteus mirabilis | Activation of pro-tumor innate immunity | Inhibit hepatic accumulation of Kupffer cells | (60) |
| Cholangiocarcinoma | Gram-negative commensal bacteria | Activation of pro-tumor innate immunity | Promote hepatic accumulation of PMN-MDSCs | (61) |
| Hepatocellular carcinoma | Vancomycin-induced gut microbiota dysbiosis | Activation of pro-tumor innate immunity | Activate M2 macrophages via IL-25 | (62) |
| Pancreatic ductal adenocarcinoma | Commensal microbiota from Rag1-/- mice | Activation of pro-tumor innate immunity | Inhibit the cytotoxicity and migration of NK cells | (63) |
| Colorectal cancer | Peptostreptococcus anaerobius | Activation of pro-tumor innate immunity | Increase the levels of IFN-γ and IL-10; promote the intratumoral infiltration of MDSCs, granulocytic tumor-associated neutrophils and TAMs | (64) |
| Colorectal cancer | Fusobacterium nucleatum | Activation of pro-tumor innate immunity | Increased the levels of CXCL1, Eotaxin, IFN-γ, IL-6, IL-9, IL-12, IL-17A, MCP-1 and TNF-α; promote the accumulation of Treg cells and MDSCs; suppress the intratumoral infiltration of Th17 cells, NK cells, CD4+ T cells and CD8+ T cells | (65) |
| Colon cancer | Candida albicans | Activation of pro-tumor innate immunity | Enhance IL-7 production by macrophages and increase IL-22 level | (66) |
| Colorectal cancer | Helicobacter hepaticus | Induction of T cell immunity | Activate CD4+ Tfh cells and facilitate the maturation of peritumoral tertiary lymphoid structures | (67) |
| Colorectal cancer | Akkermansia muciniphila | Induction of T cell immunity | Facilitate the expansion and activation of CTLs | (68) |
| Colon cancer | Alistipes senegalensis, Bacteroides dorei, Bacteroides uniformis JCM 5828, Eubacterium limosum, Fusobacterium ulcerans, Parabacteroides distasonis, Parabacteroides gordonii, Parabacteroides johnsonii, Paraprevotella xylaniphila, Phascolarctobacterium faecium and Ruminococcaceae bacterium cv2 | Induction of T cell immunity | Increase the frequency of IFN-γ+ CD8 TILs | (69) |
| Colon adenocarcinoma | Commensal microbiota from B cell-defective mice | Induction of T cell immunity | Foster the expansion of CD8+ T cells | (70) |
| Colorectal cancer, melanoma | Anaerostipes caccae, Eubacterium hallii, Faecalibacterium prausnitzii and Roseburia intestinalis | Induction of T cell immunity | Enhance the intratumoral infiltration and activation of CD8+ T cells | (71) |
| Melanoma | Commensal microbiota from Rnf5-/- mice | Induction of T cell immunity | Increase the frequency of TILs and improve antitumor cytokine response | (72) |
| Breast cancer, hepatocellular carcinoma | Escherichia coli strain Nissle 1917 | Induction of T cell immunity | Promote tumor-specific effector T cell infiltration and induce DC maturation | (73) |
| Cutaneous melanoma | Acinetobacter, Flammeovirga, Gelidibacter and Lachnoclostridium | Induction of T cell immunity | Increase the levels of tumor-infiltrating CD8+ T cells and chemokines | (74) |
| Colorectal cancer | Gut microbiota dysbiosis | Suppression of T cell immunity | Induce T cell exhaustion | (75) |
| Melanoma, lung carcinoma | Antibiotic-induced gut microbiota dysbiosis | Suppression of T cell immunity | Reduce the count of intratumoral effector T cells and decrease the serum level of TNF-α | (76) |
| Hepatocellular carcinoma | Commensal microbiota | Suppression of T cell immunity | Induce the expansion of IL-10+ Treg cells and inhibit the expansion of cytotoxic CD8+ T cells | (16) |