Specifically, they found that acetic acid derived from B. thetaiotaomicron can induce M1 macrophage polarization in HCC, thereby increasing the secretion of CD8+T cells, IFN-γ, and granzyme B by cytokines and ultimately enhancing T cell-mediated tumor cell killing (Figure 2B) (66). Here, CD8A is linked to hepatocellular carcinoma.