Hyperglucosylated adhesin‐derived peptides as antigenic probes in multiple sclerosis: Structure optimization and immunological evaluation. (12th August 2020)

• Record Type: Journal Article
• Authors: Mazzoleni, Antonio; Real‐Fernandez, Feliciana; Larregola, Maud; Nuti, Francesca; Lequin, Olivier; Papini, Anna Maria; Mallet, Jean‐Maurice; Rovero, Paolo
• Is Part Of: Journal of peptide science. Volume 26:Number 11(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-08-12
• Subjects: antibodies -- glycopeptides -- multiple sclerosis -- peptide antigenic probes; Peptides -- Periodicals; Peptides -- Periodicals; 572.65
• DOI: 10.1002/psc.3281
• Languages: English
• ISSNs: 1075-2617

Abstract

Abstract : Peptides mimicking antigenic epitopes targeted by antibodies can be powerful tools to be used as antigen surrogates for the specific diagnosis and treatment of autoimmune diseases. Obtaining structural insights about the nature of peptide–antibody interaction in complex mixtures such as sera is a critical goal. In multiple sclerosis (MS), we previously demonstrated that the N ‐linked β‐d ‐glucopyranosyl moieties ( N ‐Glc) containing epitopes in nontypeable Haemophilus influenzae adhesin C‐terminal portion HMW1(1205–1526) were essential for high‐affinity antibody binding in a subpopulation of MS patients. With the aim of developing peptide probes and assessing their binding properties to antibodies from sera of representative patients, we performed the systematic analysis of synthetic peptides based on HMW1(1347–1354) fragment bearing one or two N ‐Glc respectively on Asn‐1349 and/or Asn‐1352. The N ‐glucosylated nonapeptides efficiently bind to IgG antibodies, displaying IC50 in the range 10 −8 –10 −10 M by competitive indirect enzyme‐linked immunosorbent assay (ELISA) in three representative MS patient sera. We selected the di‐ N ‐glucosylated adhesin peptide Ac‐KAN (Glc)VTLN (Glc)TT‐NH2 as the shortest sequence able to inhibit high‐avidity interaction with N ‐Glc targeting IgM antibodies. Nuclear magnetic resonance (NMR)‐ and circular dichroism (CD)‐based characterization showed that the binding properties of these antigens could not be ascribed to structural differences induced by the presence of up to two N ‐glucosyl moieties. Therefore, the antibody binding is not easily correlated to the position of the sugar or to a determined conformation in water. Abstract : Here, we present the analysis of synthetic N ‐glucopeptides mimicking an epitope of the bacterial HMW1 adhesin, a previously identified antigen in multiple sclerosis. We evaluated their binding properties to antibodies from sera of representative patients and assessed their conformational features by NMR and CD analysis. We selected the HMW1(1347–1354) fragment containing two Asn‐linked glucose moieties as a novel peptide probe as a potential diagnostic tool and a promising therapeutic agent.