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A proinflammatory peptide from Helicobacter pylori activates monocytes to induce lymphocyte dysfunction and apoptosis

Journal article
Authors Åsa Betten
Johan Bylund
T. Christophe
F. Boulay
Ana Romero
Kristoffer Hellstrand
Claes Dahlgren
Published in J Clin Invest
Volume 108
Issue 8
Pages 1221-8
Publication year 2001
Published at Institute of Internal Medicine, Dept of Rheumatology and Inflammation Research
Institute of Laboratory Medicine, Dept of Clinical Virology
Pages 1221-8
Language en
Links www.ncbi.nlm.nih.gov/entrez/query.f...
Keywords Adenocarcinoma/etiology, Amino Acid Sequence, Apoptosis, Bacterial Proteins/chemistry/*immunology/pharmacology, Chemotaxis, Leukocyte, Gastritis/etiology, Helicobacter Infections/etiology, Helicobacter pylori/*immunology/*pathogenicity, Humans, Inflammation Mediators/chemistry/immunology/pharmacology, Lymphocytes/cytology/immunology, Molecular Sequence Data, Monocytes/*immunology, NADPH Oxidase/metabolism, Peptides/chemistry/*immunology/pharmacology, Receptors, Formyl Peptide, Receptors, Immunologic/immunology, *Receptors, Lipoxin, Receptors, Peptide/immunology, Stomach Neoplasms/etiology
Subject categories Medical and Health Sciences

Abstract

Infection with Helicobacter pylori causes chronic gastritis, which is characterized by a dense mucosal infiltration by inflammatory cells such as monocytes/macrophages. H. pylori-induced inflammation is a risk factor for the development of gastric adenocarcinoma, but the mechanisms involved in H. pylori-associated carcinogenesis are poorly understood. A cecropin-like H. pylori peptide, Hp(2-20), was found to be a monocyte chemoattractant and activated the monocyte NADPH-oxidase to produce oxygen radicals. The receptors mediating monocyte activation were identified as FPRL1 and the monocyte-specific orphan receptor FPRL2. Hp(2-20)-activated monocytes inhibited lymphocytes with antitumor properties, such as CD56+ natural killer (NK) cells and CD3epsilon+ T cells. The changes observed in NK cells and T cells--a reduced antitumor cytotoxicity, downregulation of CD3zeta expression, and apoptosis--were mediated by Hp(2-20)-induced oxygen radicals. Histamine, a gastric mucosal constituent, rescued NK cells and T cells from inhibition and apoptosis by suppressing Hp(2-20)-induced oxygen radical formation. We conclude that H. pylori expression of this monocyte-activating peptide contributes to its ability to attract and activate monocytes and reduces the function and viability of antineoplastic lymphocytes. These novel mechanisms may be subject to local, histaminergic regulation in the gastric mucosa.

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