Lineage-Specific CagA Binding Mechanics and Microenvironmental Rewiring in East Asian Gastric Carcinogenesis.

Chronic infection with Helicobacter pylori (H. pylori) is a major environmental risk factor for gastric carcinogenesis. Malignancy is largely driven by variations within the virulence factor CagA, with East Asian lineages exhibiting higher oncogenic potential than Western ones. However, how these variants modulate cellular crosstalk remains poorly understood. We integrated molecular dynamics (MD) simulations with single-cell transcriptomics across progressive disease stages, including chronic atrophic gastritis, intestinal metaplasia, and gastric cancer. Local niche remodeling was evaluated via cell-cell communication profiling among epithelial, stromal, and immune circuits, while simulations of MARK2 kinase bound to distinct CagA lineages determined binding affinities. Single-cell analysis revealed that H. pylori toxicity progressively dampens epithelial-stromal crosstalk, marked by severe epithelial polarity aberrations that disrupt neuroendocrine-like secretory and synaptic pathways during malignant transformation. Mechanistically, MD simulations and MM/GBSA calculations demonstrated that East Asian CagA lineages exhibit higher binding affinity toward host MARK2 than Western lineages. Specific East Asian amino acid substitutions dramatically tighten the protein interface, driving stronger signaling perturbations. This study bridges atomistic structural virulence with microenvironmental shifting, establishing geographic CagA toxicity divergence as a critical determinant for pathogen-driven gastric cancer risk.