The main findings of the study were that H. pylori-infected children with gastritis showed the following: (1) increased level of plasma MMP-2 and TIMP-2, (2) low frequencies of circulating TIMP-1+ and TIMP-2+ leukocytes, (3) increased intracellular expression of MMP-2 in the circulating lymphocytes and neutrophils, and (4) high expression of mRNA for MMP-9 along with low expression of mRNA for MMP-2 in the gastric mucosa. Here, MMP9 is linked to gastritis.