title: Lack of humoral response against Helicobacter pylori peptides homologous to human ZnT8 in Hashimoto's thyroiditis patients.
abstract: BACKGROUND
  The Helicobacter pylori (HP) reinfection rate seems to be higher in developing countries than in developed ones. An increased seroprevalence of HP has also been reported in patients with type 1 diabetes (T1D) and Hashimoto's thyroiditis (HT). Mycobacterium avium subsp. paratuberculosis (MAP) has been linked to both T1D and HT. Quite a few lines of evidence indicate that autoantibodies against several epitopes belonging to human zinc transporter 8 (ZnT8) cross-recognize the homologous MAP3865c epitopes in both T1D and HT patients. HP may play a role in HT disease, most likely acting through a molecular mimicry mechanism that targets ZnT8 as reported for MAP and the two autoimmune diseases.
  
  
  METHODS
  An enzyme-linked immunosorbent assay (ELISA) has been developed for the detection of antibodies against several epitopes deriving from HP proteins, which are highly homologous to the immunodominant ZnT8 peptides previously identified: ZnT8178-186 and ZnT8186-194.
  
  
  RESULTS
  None of the HP peptides tested were significantly recognized when the humoral responses of 92 HT patients and 91 healthy volunteers were analyzed.
  
  
  CONCLUSIONS
  These findings do not support a triggering role for HP (through ZnT8 mimicking) in HT. If a molecular mimicry phenomenon is taking place, it involves a different self-antigen. Moreover, the negative outcome of the experiments performed stresses the fact that sharing stretches of sequence homology is relevant, but not enough to trigger an antibody-mediated cross-recognition.
authors.affiliation: University of Sassari, Sassari, Italy. speranza.masala@tiscali.it.
authors.forename: Speranza
authors.initials: S
authors.lastname: Masala
authors.forename: Davide
authors.initials: D
authors.lastname: Cossu
authors.forename: Magdalena
authors.initials: M
authors.lastname: Niegowska
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mameli
authors.forename: Daniela
authors.initials: D
authors.lastname: Paccagnini
authors.forename: Leonardo A
authors.initials: LA
authors.lastname: Sechi
mesh_terms: D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology; D027682:Cation Transport Proteins / Q000276:immunology*; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D050031:Hashimoto Disease / Q000150:complications*; D016481:Helicobacter Infections / Q000276:immunology*; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D000075703:Zinc Transporter 8
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001323:Autoantibodies; D027682:Cation Transport Proteins; C492522:SLC30A8 protein, human; D000075703:Zinc Transporter 8