H. pylori-generated CagA enters GC cells, downregulates p53 levels to reduce miR-34a levels, promotes the secretion of GX-EX carrying PD-L1 into the extracellular milieu, facilitating immune evasion in GC, inhibiting the proliferation of CD8 + T cells and cytokine secretion. Here, S100A8 is linked to gastric cancer.