Designed Glucopeptides Mimetics of Myelin Protein Epitopes As Synthetic Probes for the Detection of Autoantibodies, Biomarkers of Multiple Sclerosis

Abstract

We previously reported that CSF114(Glc) detects diagnostic autoantibodies in multiple sclerosis sera. We report herein a bioinformatic analysis of myelin proteins and CSF114(Glc), which led to the identification of five sequences. These glucopeptides were synthesized and tested in enzymatic assays, showing a common minimal epitope. Starting from that, we designed an optimized sequence, SP077, showing a higher homology with both CSF114(Glc) and the five sequences selected using the bioinformatic approach. SP077 was synthesized and tested on 50 multiple sclerosis patients' sera, and was able to detect higher antibody titers as compared to CSF114(Glc). Finally, the conformational properties of SP077 were studied by NMR spectroscopy and structure calculations. Thus, the immunological activity of SP077 in the recognition of specific autoantibodies in multiple sclerosis patients' sera may be ascribed to both the optimized design of its epitopic region and the superior surface interacting properties of its C-terminal region.

Antibody Recognition in multiple sclerosis and rett syndrome using a collection of linear and cyclic N‐glucosylated antigenic probes

“…3 Therefore, synthetic peptides compared to recombinant proteins have the advantage to be easily and specifically modified during the synthetic process with the aberrant post-translational modifications in order to mimic and selectively detect specific autoantibodies as disease biomarkers. 12,13 This result was the proof-of-concept of our "Chemical Reverse Approach": peptide structures manipulation can lead to the discovery of cryptic autoantigens by increasing epitope specific antibody recognition. 5,6 We previously developed the N-glucosylated peptide CSF114(Glc) as a mimetic antigen, selected and optimized from a library of different peptide secondary structures.…”

“…Similarly, Figure 1C, shows that the linear peptides Ac-NPra-ERPN(Glc)HT-NPra-NH 2 (11), Ac-Pra-ERPN(Glc)HT-Pra-NH 2 (12), and Ac-NPra-RRPN(Glc)HT-NPra-NH 2 (14) are more potent (with IC 50 5 5.8, 22, and 21 nM, respectively) than the cyclic analogs Ac-c[NPra-ERPN(Glc)HT-NPra]-NH 2 (13) and Ac-c[CRRPN(Glc)HTC]-NH 2 (15) (with IC 50 5 69.2 and 1700 nM, respectively) and, more interestingly, than the reference sequences, i.e., type I 0 b-turn CSF114(Glc) (IC 50 5 45 nM) and a type I b-turn analog containing a Pro-Asn(Glc) sequence, Ac-NPra-RRPN(Glc)HT-NPra-NH 2 (14) (IC 50 5 21 nM). The linear octapeptides (9) and (11), containing either two L-Pra with the RRN(Glc)GHT sequence or NPra with the ERPN(Glc)HT sequence, displayed the highest inhibitory potency (IC 50 5 6.8 and 5.8 nM, respectively) in this competition assay compared to the reference compound CSF114(Glc).…”

pH‐regulated formation of side products in the reductive amination approach for differential labeling of peptides in relative quantitative experiments

“…Peptides 5-9 were synthesized by a fluorenylmethoxycarbonyl (Fmoc)/tert-butyl (tBu) solid-phase peptide strategy as previously reported [31], purified to homogeneity by preparative reverse-phase HPLC, and characterized by ESI-MS-HPLC.…”

Filaggrin Peptides with β‐Hairpin Structure Bind Rheumatoid Arthritis Antibodies

“…[11][12][13] Obviously, the epitope of an antibody-binding peptide should be presented in a b-turn within a conformational stable b-hairpin. There are different well-known strategies to direct peptides into conformationally homogeneous structures.…”