Study of Aberrant Modifications in Peptides as a Test Bench to Investigate the Immunological Response to Non-Enzymatic Glycation

Nuti, F.; Gallo, A.; Real-Fernandez, F.; Rentier, C.; Rossi, G.; Piarulli, F.; Traldi, P.; Carganico, S.; Rovero, P.; Lapolla, Annunziata; Papini, Anna Maria

doi:10.14712/fb2019065040195

Folia Biologica > Archive > 2019, Vol. 65 > Issue 4 > Study of Aberrant Modifications in…

Fol. Biol. 2019, 65, 195-202

https://doi.org/10.14712/fb2019065040195

Study of Aberrant Modifications in Peptides as a Test Bench to Investigate the Immunological Response to Non-Enzymatic Glycation

F. Nuti¹, A. Gallo², F. Real-Fernandez¹, C. Rentier^1,3, G. Rossi^4,5, F. Piarulli², P. Traldi⁶, S. Carganico^1,5, P. Rovero⁴, Annunziata Lapolla², Anna Maria Papini^1,3

¹Laboratory of Peptide and Protein Chemistry and Biology, Department of Chemistry „Ugo Schiff“, University of Florence, Sesto Fiorentino, Italy
²Diabetology and Dietetics, Department of Medicine (DIMED), University of Padova, Padova, Italy
³PeptLab@UCP Platform and Laboratory of Chemical Biology EA4505, University Paris-Seine, Cergy-Pontoise CEDEX, France
⁴Laboratory of Peptide and Protein Chemistry and Biology, Department of NeuroFarBa, University of Florence, Sesto Fiorentino, Italy
⁵Pharma Quality Europe PQE SrL, Località Prulli, Firenze, Italy
⁶Istituto di Ricerca Pediatrica, Città della Speranza, Padova, Italy

Received May 2019
Accepted June 2019

A side effect of diabetes is formation of glycated proteins and, from them, production of advanced early glycation end products that could determine aberrant immune responses at the systemic level. We investigated a relevant aberrant post-translational modification (PTM) in diabetes based on synthetic peptides modified on the lysine side chain residues with 1-deoxyfructopyranosyl moiety as a possible modification related to glycation. The PTM peptides were used as molecular probes for detection of possible specific autoantibodies developed by diabetic patients. The PDC-E2(167-186) sequence from the pyruvate dehydrogenase complex was selected and tested as a candidate peptide for antibody detection. The structure-based designed type I’ β-turn CSF114 peptide was also used as a synthetic scaffold. Twenty-seven consecutive type 1 diabetic patients and 29 healthy controls were recruited for the study. In principle, the ‘chemical reverse approach’, based on the use of patient sera to screen the synthetic modified peptides, leads to the identification of specific probes able to characterize highly specific autoantibodies as disease biomarkers of autoimmune disorders. Quite surprisingly, both peptides modified with the (1-deoxyfructosyl)-lysine did not lead to significant results. Both IgG and IgM differences between the two populations were not significant. These data can be rationalized considering that i) IgGs in diabetic subjects exhibit a high degree of glycation, leading to decreased functionality; ii) IgGs in diabetic subjects exhibit a privileged response vs proteins containing advanced glycation products (e.g., methylglyoxal, glyoxal, glucosone, hydroimidazolone, dihydroxyimidazolidine) and only a minor one with respect to (1-deoxyfructosyl)-lysine.

Keywords

protein glycation, immunological response, peptide, β-turn peptide structure, type 1 diabetes, SP-ELISA.

Funding

ANR Chaire d’Excellence 2009–2014 (grant No. ANR-09-CEXC-013-01 to AMP), French-Italian University (Vinci Project grant No. C2-133 to CR), and Ente Cassa di Risparmio di Firenze (grant No. 2014/0306) are gratefully acknowledged for their financial support.