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Abstract

I thank Danese et al. for their comments about our editorial on the induction of matrix metalloproteinase-9 (MMP-9) expression by Helicobacter pylori infection.1Mori N. Sato H. Hayashibara T. Senba M. Geleziunas R. Wada A. Hirayama T. Yamamoto N. Helicobacter pylori induces matrix metalloproteinase-9 through activation of nuclear factor κB.Gastroenterology. 2003; 124: 983-992Abstract Full Text Full Text PDF PubMed Scopus (106) Google Scholar They report in their letter that MMP-9 expression has been reduced after H. pylori eradication both in epithelial cells and in mucosal fibroblasts. I acknowledge that their data confirm my findings and support my conclusions. I read with interest the data from this eradication study. They report no change of MMP-9 expression after eradication in macrophages. I observed no association between MMP-9 expression and H. pylori infection in macrophages in gastric ulcers.1Mori N. Sato H. Hayashibara T. Senba M. Geleziunas R. Wada A. Hirayama T. Yamamoto N. Helicobacter pylori induces matrix metalloproteinase-9 through activation of nuclear factor κB.Gastroenterology. 2003; 124: 983-992Abstract Full Text Full Text PDF PubMed Scopus (106) Google Scholar These results suggest distinct mechanism of MMP-9 expression between epithelial cells and fibroblasts, and macrophages. MMP-9 expression in epithelial cells and fibroblasts is dependent on H. pylori infection, whereas in macrophages it is independent of H. pylori infection. The increase of MMP-9 in macrophages may be causally linked to the mucosal injury. The plasma levels of MMP-9 in patients with gastric cancer were significantly higher than those in healthy individuals.2Torii A. Kodera Y. Uesaka K. Hirai T. Yasui K. Morimoto T. Yamamura Y. Kato T. Hayakawa T. Fujimoto N. Kito T. Plasma concentration of matrix metalloproteinase 9 in gastric cancer.Br J Surg. 1997; 84: 133-136Crossref PubMed Scopus (67) Google Scholar It is possible that the plasma levels of MMP-9 are increased in patients with H. pylori-associated gastritis and gastric ulcer. I am under investigation the plasma levels of MMP-9 in these patients.