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Figure 4. Bidirectional role of the gut microbiota-liver axis in shaping the immune microenvironment of HCC. The diagram illustrates the dual mechanisms by which microbiota composition dictates hepatic immune tone. Solid green arrows indicate direct beneficial interactions or activation; solid red arrows indicate pathogenic activation or oncogenic signaling; dashed arrows represent translocation from the gut to the liver via the portal vein; red T-bars represent direct suppression or inhibition of immune cells. Detailed cellular and molecular mechanisms, including specific microbial strains, are discussed in the corresponding text. HCC: Hepatocellular carcinoma.