title: Role of Lipoylation of the Immunodominant Epitope of Pyruvate Dehydrogenase Complex: Toward a Peptide-Based Diagnostic Assay for Primary Biliary Cirrhosis.
abstract: Primary biliary cirrhosis is an immune-mediated chronic liver disease whose diagnosis relies on the detection of serum antimitochondrial antibodies directed against a complex set of proteins, among which pyruvate dehydrogenase complex is considered the main autoantigen. We studied the immunological role of the lipoyl domain of this protein using synthetic lipoylated peptides, showing that the lipoyl chain chirality does not affect autoantibody recognition and, most importantly, confirming that both lipoylated and unlipoylated peptides are able to recognize specific autoantibodies in patients sera. In fact, 74% of patients sera recognize at least one of the tested peptides but very few positive sera recognized exclusively the lipoylated peptide, suggesting that the lipoamide moiety plays a marginal role within the autoreactive epitope. These results are supported by a conformational analysis showing that the lipoyl moiety of pyruvate dehydrogenase complex appears to be involved in hydrophobic interactions, which may limit its exposition and thus its contribution to the complex antigenic epitope. A preliminary analysis of the specificity of the two most active peptides indicates that they could be part of a panel of synthetic antigens collectively able to mimic in a simple immunoenzymatic assay the complex positivity pattern detected in immunofluorescence.
authors.forename: Giulia
authors.initials: G
authors.lastname: Pacini
authors.affiliation: Department of Pharmacy, University of Naples "Federico II" , Via D. Montesano 49, 80131 Napoli, Italy.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Carotenuto
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Florence , Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy.|PeptLab@UCP Platform and Laboratory of Chemical Biology EA4505, University of Cergy-Pontoise , 5 Mail Gay-Lussac, 95031 Cergy-Pontoise Cedex, France.
authors.forename: Cedric
authors.initials: C
authors.lastname: Rentier
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Florence , Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Nuti
authors.forename: Feliciana
authors.initials: F
authors.lastname: Real-Fernandez
authors.affiliation: Department of Pharmacy, University of Naples "Federico II" , Via D. Montesano 49, 80131 Napoli, Italy.
authors.forename: Diego
authors.initials: D
authors.lastname: Brancaccio
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Florence , Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Sabatino
authors.affiliation: PeptLab@UCP Platform and Laboratory of Chemical Biology EA4505, University of Cergy-Pontoise , 5 Mail Gay-Lussac, 95031 Cergy-Pontoise Cedex, France.
authors.forename: Maud
authors.initials: M
authors.lastname: Larregola
authors.affiliation: PeptLab@UCP Platform and Laboratory of Chemical Biology EA4505, University of Cergy-Pontoise , 5 Mail Gay-Lussac, 95031 Cergy-Pontoise Cedex, France.
authors.forename: Elisa
authors.initials: E
authors.lastname: Peroni
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa , Via Roma 67, 56126 Pisa, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Migliorini
authors.affiliation: Department of Pharmacy, University of Naples "Federico II" , Via D. Montesano 49, 80131 Napoli, Italy.
authors.forename: Ettore
authors.initials: E
authors.lastname: Novellino
authors.affiliation: Department of Health Sciences, Division of Medicine and Gastroenterology and Liver Unit, University of Milan , Ospedale San Paolo, Via Antonio Di Rudinì 8, 20142 Milano, Italy.
authors.forename: Pier Maria
authors.initials: PM
authors.lastname: Battezzati
authors.affiliation: Division of Rheumatology and Clinical Immunology, IRCCS Istituto Clinico Humanitas , Via Alessandro Manzoni 56, 20089 Rozzano, Milano, Italy.|BIOMETRA Department, University of Milan , Via Festa del Perdono 7, 20122 Milano, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Selmi
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Florence , Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy.|PeptLab@UCP Platform and Laboratory of Chemical Biology EA4505, University of Cergy-Pontoise , 5 Mail Gay-Lussac, 95031 Cergy-Pontoise Cedex, France.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Papini
authors.forename: Paolo
authors.initials: P
authors.lastname: Rovero
mesh_terms: D000941:Antigens / Q000737:chemistry; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D006801:Humans; D016056:Immunodominant Epitopes / Q000276:immunology*; D007124:Immunoenzyme Techniques; D008105:Liver Cirrhosis, Biliary / Q000097:blood / Q000175:diagnosis* / Q000201:enzymology; D008968:Molecular Conformation; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry; D030481:Pyruvate Dehydrogenase (Lipoamide) / Q000097:blood / Q000737:chemistry / Q000276:immunology; D011768:Pyruvate Dehydrogenase Complex / Q000097:blood / Q000737:chemistry* / Q000276:immunology*; D013329:Structure-Activity Relationship
chemical_list: D000941:Antigens; D016056:Immunodominant Epitopes; D010455:Peptides; D011768:Pyruvate Dehydrogenase Complex; D030481:Pyruvate Dehydrogenase (Lipoamide)