Fig. 2

Intra-tumoral microbes provide antigenicity and adjuvanticity to promote inflammatory tumor immune microenvironment. Microbial antigens can be presented by HLA molecules on both tumor cells and tumor-infiltrating immune cells, informing their potential to elicit anti-tumoral response. Microbe antigens share similar antigen epitopes with tumor antigens and elicit microbe-specific T cells that can recognize and kill tumor cells. Microbes lyse tumor cells to release TAA, DAMP, and PAMP to elicit inflammatory tumor immune microenvironment. Also, microbe themselves serve as immunostimulatory adjuvants to further promote inflammatory tumor immune microenvironment. Abbreviations: CD = cluster of differentiation, DAMP = damage-associated molecular pattern, HLA = human leukocyte antigen, IFNγ = interferon-gamma, MHC = major histocompatibility complex, PAMP = pathogen-associated molecular pattern, PRR = pattern recognition receptor, TAA = tumor-associated antigen, TCR = T-cell receptor, TNFα = tumor necrosis factor-alpha