Picascia, Stefania (2014) Identification of gliadin peptides immunogenic for celiac patients. [Tesi di dottorato]

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Tipologia del documento: Tesi di dottorato
Lingua: English
Titolo: Identification of gliadin peptides immunogenic for celiac patients
Autori:
AutoreEmail
Picascia, Stefaniastefaniapicascia@hotmail.it
Data: 31 Marzo 2014
Numero di pagine: 158
Istituzione: Università degli Studi di Napoli Federico II
Dipartimento: Scienze Mediche Traslazionali
Scuola di dottorato: Medicina clinica e sperimentale
Dottorato: Riproduzione, sviluppo ed accrescimento dell'uomo
Ciclo di dottorato: 26
Coordinatore del Corso di dottorato:
nomeemail
Pignata, Claudiopignata@unina.it
Tutor:
nomeemail
Troncone, Riccardo[non definito]
Data: 31 Marzo 2014
Numero di pagine: 158
Parole chiave: Celiac diseae; gliadin peptides
Settori scientifico-disciplinari del MIUR: Area 06 - Scienze mediche > MED/38 - Pediatria generale e specialistica
Aree tematiche (7° programma Quadro): SALUTE e TUTELA DEL CONSUMATORE > Biotecnologie, strumenti e tecnologie generiche per la salute umana
Depositato il: 10 Apr 2014 10:00
Ultima modifica: 15 Lug 2015 01:01
URI: http://www.fedoa.unina.it/id/eprint/9873

Abstract

Celiac disease (CD) is a multifactorial disorders affecting susceptible individual following ingestion of gluten and related prolamines. It’s accepted that ingestion of gluten activates an immune cascade responsible for lymphocytic infiltration and destruction of the intestinal mucosa.The repertoire of gluten peptides activating the CD4+T cells restricted by CD-associated HLA DQ2 and DQ8 molecules, is well established, particularly in adult celiac patients. Conversely, very little is known about the repertoire of gluten peptides active in children celiacs, as well as the antigen specificity of CD8+T cells that massively infiltrate celiac intestinal mucosa. We aimed to investigate the repertoire of gluten peptides responsible of the inflammatory cascade both in acute disease, characterized by villous atrophy, as well as in the early and mild disorder, such as potential celiac disease. Furthermore we investigated the role of deamidation by tTGase in shaping the repertoire of gluten peptides. The comprehensive elucidation of pathogenic gluten peptidesmay have several translational applications, as the design of peptide-based therapies, alternative to the gluten exclusion diet, or the searching of grains with reduced or total absence of pathogenic sequences for prevention of the disease in at risk subjects. Although celiac disease is associated with HLA class II alleles coding for DQ2/8 heterodimers initial studies reported an increased frequency of HLA Class-I A*01 and B*08 alleles among CD subjects. Since A*01 and B*08 alleles are in strong linkage disequilibrium with the DR3-DQ2 haplotype, the role of A1 and B8 molecules in presenting gluten peptides to CD8 T cells should be revaluated. In order to identify potential HLA Class I-restricted epitopes, six gliadin proteins were screened and top 1% scoring peptides were synthesized and assayed for recognition in celiac patients grouped according to their positivity for A1 and/or B8 alleles. Ten peptides induced strong IFN-gamma responses in CD8+T cells from a subgroup of celiac patients, particularly in B8 positive CD volunteers. Importantly, these CTL epitopes are active in their native, non tTG-deamidated form. Immunogenicity of the selected peptides was further assessed on short-term CTL obtained from PBMC of responsive celiac patients. Several studies identified gluten peptides restricted by HLA class II immunodominant for adult celiacs. We investigated the contribution of gliadin-specific T cell response in childhood or adolescent CD by analyzing the T-cell reactivity to five peptides found immune-dominant in adult celiacs. Gliadin-specific T cell lines were generated by jejunal biopsies of young subjects and gliadin-specificity was assessed by IFN-gamma-ELISPOT and ELISA. Results shown a significant response (p<0.05) in IFN-gamma production in subjects with active or potential CD, but no in subjects without CD. Furthermore, children patients recognized the same pattern of gluten peptides found to be dominant in adult CD, such as DQ2.5-glia-alpha-1a/glia-alpha-2; DQ2.5-omega-1/glia-omega-2; DQ2.5-glia-γ-1; DQ2.5-glia-γ-2; DQ2.5-glia-γ-3/glia-γ-4b and 4c/ glia-γ5/glia-γ-2 in both naïve and deamidated forms. In conclusion, gliadin-specific T cell responses were found in intestinal mucosa of young subjects that presents autoantibodies (anti-tTG IgA) that are serology marker of disease, but a histologically and morphologically normal mucosa. Patients with potential CD had similar magnitude of IFN-γ responses of patients with mucosal atrophy, as well as similar pattern of active gliadin epitopes. Our results highlight the use of intestinal T cell response to gliadin as an additional diagnostic tool in the doubted cases of CD. Overall the present study offers new lights in the definition of the repertoire of gliadin peptides restricted by HLA class I & II recognized by celiac patients and involved in the pathogenesis of celiac disease.

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