Table 2.
Possible Mechanisms of Oral Bacteria in the Gut Pathogenesis.
| Pathways in Host Cells | ||||
|---|---|---|---|---|
| Oral Bacteria: Target Cells | Effector | Receptor | Related Signals | Pathologic Functions |
| Fusobacterium nucleatum | ||||
| Epithelial cells | Fap2 | Gal-GalNAc | Tumor binding and enrichment | |
| Epithelial cells | Metalloproteinase collagenase | Cellular migration and invasive properties | ||
| Epithelial cells | FadA | Ecad | Wnt/β-catenin | Tumor cell proliferation |
| NK cells, T cells | Fap2 | TIGIT | Immune evasion | |
| Epithelial cells | LPS | TLR4 | miR-4802, miR-18a* | Chemoresistance (autophagy activation) |
| Epithelial cells | LPS | TLR4 | Myd88, miR-21 | Tumor cell proliferation |
| Recruitment of tumor-infiltrating immune cells (MDSC, TAM, regDC) | ||||
| Fusobacterium varium epithelial cells | Adhesion and invasion, IL-8 and TNF-a production | |||
| Porphyromonas gingivalis | ||||
| Epithelial cells | Jak1/Akt/Stat3, PI3K/Akt | Cell survival (antiapoptotic) | ||
| Epithelial cells | Cyclin D and E, PI3K | Cell proliferation | ||
| Epithelial cells | Gingipain | β-catenin destruction, complex degradation | β-catenin | Cell proliferation |
| Epithelial cells | Immune evasion (B7-H1 and B7-DC upregulation) | |||
| Epithelial cells | Gingipain | PAR | NF-kB, ERK1/2, p38 | Tumor invasiveness (MMPs expression↑) |
| Epithelial cells and others | Epithelial disruption, proinflammatory cytokine induction, gut dysbiosis | |||
| Epithelial cells and others | Epithelial disruption, immune activation, gut dysbiosis | |||
| Neutrophils | TLR1-TLR2 | Myd88 | Impaired antimicrobial response, Impaired killing activity | |
| Mø and DC | Fimbrial proteins (FimA and Mfa1) | CR3 or DC-SIGN | MMP and C1q | Hijack and direct host immune cells (distant tissue destruction) |
| Klebsiella pneumoniae, K. aerogenes (K. aeromobilis) epithelial cells | TLR | IL18 and Myd88 | Th1 cell generation | |
| Atopobium parvulum: unknown | H2S | Mitochondrial dysfunction in host with impaired H2S detoxification | ||
| Campylobacter concisus epithelial cells | Epithelial disruption | |||
| Staphylococcus aureus epithelial cells, T cells | Enterotoxins | Epithelial disruption, immune activation | ||