H. pylori culture and infection.

A standard strain of H. pylori ATCC 43504 (MINGZHOUBIO) and H. pylori Sydney strain 1 (SS1) provided by Hebei Medical University were inoculated in the Columbia agar plate (Oxoid), and then cultured at 37°C under microaerobic conditions (5% O₂, 10% CO₂, and 85% N₂) for 48 h. Before infection, H. pylori was cultured in the antibiotic-free DMEM overnight. Then, the H. pylori culture was diluted with DMEM to a suspension at 1.0 × 10⁷ CFU/mL to infect GES-1 cells at a multiplicity of infection (MOI) of 100:1 for 24h.