Our data suggest that (1) MMPs are important contributors to stomach remodelling in children with H. pylori-related gastritis, (2) remodelling of stomach ECM is regulated by lymphocytes and neutrophils, through the production of more protective MMP-2, and (3) unsuccessful H. pylori-eradication is associated with increased MMP-9 in plasma, circulating lymphocytes, and in gastric mucosa. Here, MMP9 is linked to gastritis.