title: Molecular mimicry by Helicobacter pylori CagA protein may be involved in the pathogenesis of H. pylori-associated chronic idiopathic thrombocytopenic purpura.
abstract: The eradication of Helicobacter pylori often leads to platelet recovery in patients with chronic idiopathic thrombocytopenic purpura (cITP). Although this clinical observation suggests the involvement of H. pylori, little is known about the pathogenesis of cITP. We initially examined the effect of H. pylori eradication on platelet counts in 20 adult Japanese cITP patients. Then, using platelet eluates as the probe in immunoblot analyses, we examined the role of molecular mimicry in the pathogenesis of cITP. Helicobacter pylori infection was detected in 75% (15 of 20) of cITP patients. Eradication was achieved in 13 (87%) of the H. pylori-positive patients, seven (54%) of which showed increased platelet counts within the 4 months following treatment. Completely responsive patients also showed significant declines in platelet-associated immunoglobulin G (PAIgG) levels. Platelet eluates from 12 (nine H. pylori-positive and three H. pylori-negative) patients recognized H. pylori cytotoxin-associated gene A (CagA) protein, and in three completely responsive patients, levels of anti-CagA antibody in platelet eluates declined after eradication therapy. Cross-reactivity between PAIgG and H. pylori CagA protein suggests that molecular mimicry by CagA plays a key role in the pathogenesis of a subset of cITP patients.
authors.affiliation: Department of Bio-Signal Analysis, Yamaguchi University Graduate School of Medicine, Ube, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Takahashi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Yujiri
authors.forename: Kenji
authors.initials: K
authors.lastname: Shinohara
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Inoue
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Sato
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Fujii
authors.forename: Masashi
authors.initials: M
authors.lastname: Okubo
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Zaitsu
authors.forename: Koichi
authors.initials: K
authors.lastname: Ariyoshi
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Ryouhei
authors.initials: R
authors.lastname: Nawata
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Oka
authors.forename: Mutsunori
authors.initials: M
authors.lastname: Shirai
authors.forename: Yukio
authors.initials: Y
authors.lastname: Tanizawa
mesh_terms: D000293:Adolescent; D000328:Adult; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D005260:Female; D016481:Helicobacter Infections / Q000150:complications / Q000276:immunology*; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D015151:Immunoblotting; D008297:Male; D008875:Middle Aged; D018716:Molecular Mimicry / Q000276:immunology*; D011233:Precipitin Tests; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000276:immunology / Q000382:microbiology*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C080866:cagA protein, Helicobacter pylori