H. pylori gastritis is strongly associated with the upregulation of the expression of several matrix metalloproteinases (MMPs) in the gastric mucosa. However, the role of MMP-2 and MMP-9, and their inhibitors (tissue inhibitors of metalloproteinases -TIMPs) produced by immune cells in infected children have not been clearly defined. Moreover, the effects of H. pylori eradication therapy on MMPs and TIMPs production has not been evaluated. A total of 84 children were studied: 24-with newly diagnosed H. pylori gastritis, 25-after H. pylori eradication therapy (17 of them after successful therapy), 24-with H. pylori-negative gastritis, and 11-controls. Plasma levels of MMP-2, MMP-9, TIMP-1, and TIMP-2 by ELISA; MMPs and TIMPs expression in lymphocytes; neutrophils and monocytes in peripheral blood by multiparameter flow cytometry; and mucosal mRNA expression levels of MMPs and TIMP-1 in gastric biopsies by RT-PCR were evaluated. Children with H. pylori-related gastritis showed the following: (1) increased MMP-2 and TIMP-2 plasma levels, (2) increased intracellular expression of MMP-2 in the circulating lymphocytes and neutrophils, (3) low frequencies of circulating TIMP-1+ and TIMP-2+ leukocytes, and (4) high expression of mRNA for MMP-9 along with low expression of mRNA for MMP-2 in the gastric mucosa. Unsuccessful H. pylori eradication was associated with the following: (1) high plasma levels of MMP-9 and TIMP-1, (2) increased pool of TIMP-1+ lymphocytes as well as high expression of MMP-9 in circulating lymphocytes, and (3) high expression of mRNA for MMP-9 in the gastric mucosa. Our data suggest that MMPs are important contributors to stomach remodelling in children with H. pylori-related gastritis. Unsuccessful H. pylori eradication is associated with increased MMP-9 in plasma, circulating lymphocytes, and gastric mucosa.
Keywords: Helicobacter pylori; children; eradication therapy; matrix metalloproteinases; tissue inhibitor of metalloproteinases.