Cellular mechanism study demonstrated that stimulation with gut microbial extracts from NAFLD-related HCC subjects can increase the frequency of regulatory T cells (Tregs) and decrease the frequency of CD8+ T cells in human peripheral blood mononuclear cells (PBMCs), compared to treatment with bacterial extracts from non-NAFLD subjects (20), which indicates an important role of gut microbiota in modulating immunity in HCC microenvironment. This evidence concerns the gene CD8A and hepatocellular carcinoma.