Synthesis and biological evaluation of hapten-clicked analogues of the antigenic peptide Melan‐A/MART‐126(27L)‐35

A click chemistry‐based approach was implemented to prepare peptidomimetics designed in silico and made from aromatic azides and a propargylated GIGI‐mimicking platform derived from the altered Melan‐A/MART‐1 26(27L)‐35 antigenic peptide ELAGIGILTV. The Cu(I)‐catalyzed Huisgen cycloaddition was carried out on solid support to generate rapidly a first series of peptidomimetics, which were evaluated for their capacity to dock at the interface between the major histocompatibility complex class‐I (MHC‐I) human leucocyte antigen (HLA)‐A2 and T‐cell receptors (TCRs). Despite being a weak HLA‐A2 ligand, one of those 11 first synthetic compounds bearing a p ‐nitrobenzyl‐triazole side‐chain was recognized by the receptor proteins of Melan‐A/MART‐1‐specific T‐cells. After modifications of the N ‐ and C ‐termini of this agonist, which was intended to enhance HLA‐A2 binding, one of the resulting 7 additional compounds triggered significant T‐cell responses. Thus, these results highlight the capacity of naturally circulating human TCRs that are specific for the native Melan‐A/MART‐1 26‐35 peptide to cross‐react with peptidomimetics bearing organic motifs structurally different from the native central amino acids

Conception, étude structurale et propriétés fonctionnelles de nouveaux peptidomimes antigéniques pour une immunothérapie antitumorale

Des peptides antigéniques sont présentés à la surface des cellules cancéreuses ou infectées par un virus pour être reconnus par des cellules du système immunitaire. Cette reconnaissance déclenche alors une réponse immunitaire spécifique contre les cellules présentatrices ciblées. L'objectif de ce projet est de stimuler cette réponse immunitaire afin qu'elle soit un moyen thérapeutique pour détruire spécifiquement les cellules cancéreuses ou infectées. Toutefois, les peptides antigéniques ne peuvent pas être administrés tels quels, du fait de leur pauvre stabilité en milieu biologique. Il est donc nécessaire de les modifier afin qu’ils soient plus résistants. Le défi de ce projet est de synthétiser des peptidomimes bio-résistants, capables de reproduire la même réponse immunitaire que celle du peptide antigénique naturel.Abstrac

Conception, étude structurale et propriétés fonctionnelles de nouveaux peptidomimes antigéniques pour une immunothérapie antitumorale

Des peptides antigéniques sont présentés à la surface des cellules cancéreuses ou infectées par un virus pour être reconnus par des cellules du système immunitaire. Cette reconnaissance déclenche alors une réponse immunitaire spécifique contre les cellules présentatrices ciblées. L'objectif de ce projet est de stimuler cette réponse immunitaire afin qu'elle soit un moyen thérapeutique pour détruire spécifiquement les cellules cancéreuses ou infectées. Toutefois, les peptides antigéniques ne peuvent pas être administrés tels quels, du fait de leur pauvre stabilité en milieu biologique. Il est donc nécessaire de les modifier afin qu’ils soient plus résistants. Le défi de ce projet est de synthétiser des peptidomimes bio-résistants, capables de reproduire la même réponse immunitaire que celle du peptide antigénique naturel.Abstrac

Crystal Structures of HLA-A*0201 Complexed with Melan-A/MART-1 26(27L)-35 Peptidomimetics Reveal Conformational Heterogeneity and Highlight Degeneracy of T Cell Recognition

International audienceThere is growing interest in using tumor associated antigens presented by class I major histocompatibility complex (MHC-I) proteins as cancer vaccines. As native peptides are poorly stable in biological fluids, researchers have sought to engineer synthetic peptidomimetics with greater biostability. Here, we demonstrate that antigenic peptidomimetics of the Melan-A/MART-1 26(27L)-35 melanoma antigen adopt strikingly different conformations when bound to MHC-I, highlighting the degeneracy of T cell recognition and revealing the challenges associated with mimicking native peptide conformation

Isolation and Characterization of Fasciculin Ii: From Dendroaspis Angusticeps Snake Venom and from Chemical Synthesis

WOS:00043691790003

Isolation of an Anti-Tumour Disintegrin: Dabmaurin-1, a Peptide Lebein-1-Like, from Daboia mauritanica Venom.

International audienceIn the soft treatment of cancer tumours, consequent downregulation of the malignant tissue angiogenesis constitutes an efficient way to stifle tumour development and metastasis spreading. As angiogenesis requires integrin-promoting endothelial cell adhesion, migration, and vessel tube formation, integrins represent potential targets of new therapeutic anti-angiogenic agents. Our work is a contribution to the research of such therapeutic disintegrins in animal venoms. We report isolation of one peptide, named Dabmaurin-1, from the hemotoxic venom of snake Daboia mauritanica, and we evaluate its potential anti-tumour activity through in vitro inhibition of the human vascular endothelial cell HMECs functions involved in tumour angiogenesis. Dabmaurin-1 altered, in a dose-dependent manner, without any significant cytotoxicity, HMEC proliferation, adhesion, and their mesenchymal migration onto various extracellular matrix proteins, as well as formation of capillary-tube mimics on MatrigelTM. Via experiments involving HMEC or specific cancers cells integrins, we demonstrated that the above Dabmaurin-1 effects are possibly due to some anti-integrin properties. Dabmaurin-1 was demonstrated to recognize a broad panel of prooncogenic integrins (αvβ6, αvβ3 or αvβ5) and/or particularly involved in control of angiogenesis α5β1, α6β4, αvβ3 or αvβ5). Furthermore, mass spectrometry and partial N-terminal sequencing of this peptide revealed, it is close to Lebein-1, a known anti-β1 disintegrin from Macrovipera lebetina venom. Therefore, our results show that if Dabmaurin-1 exhibits in vitro apparent anti-angiogenic effects at concentrations lower than 30 nM, it is likely because it acts as an anti-tumour disintegrin

Design, synthesis and evaluation of β-lactam antigenic peptide hybrids; unusual opening of the β-lactam ring in acidic media

β-Lactam peptides were envisioned as conformational constraints in antigenic peptides (APs). Three different β-lactam tripeptides of varying flexibility were prepared in solution and incorporated in place of the central part of the altered melanoma associated antigenic peptide Leu₂₇-Melan-A₂₆₋₃₅ using solid phase synthesis techniques. Upon TFA cleavage from the solid support, an unexpected opening of the β-lactam ring occurred with conservation of the amide bond. After adaptation of the solid phase synthesis strategy, β-lactam peptides were successfully obtained and both opened and closed forms were evaluated for their capacity to bind to the antigen-presenting class-I MHC HLA-A2 protein system. None of the closed β-lactam peptides bound to HLA-A2, but their opened variants were shown to be moderate to good HLA-A2 ligands, one of them being even capable of stimulating a Melan-A-specific T cell line

AaTX1, from Androctonus australis scorpion venom: Purification, synthesis and characterization in dopaminergic neurons

International audienceWe have purified the AaTX1 peptide from the Androctonus australis (Aa) scorpion venom, previously cloned and sequenced by Legros and collaborators in a venom gland cDNA library from Aa scorpion. AaTX1 belongs to the alpha-Ktx15 scorpion toxins family (alpha KTx15-4). Characterized members of this family share high sequence similarity and were found to block preferentially I-A-type voltage-dependent K+ currents in rat cerebellum granular cells in an irreversible way. In the current work, we studied the effects of native AaTX1 (nAaTX1) using whole-cell patch-clamp recordings of I-A current in substantia nigra pars compacta dopaminergic neurons. At 250 nM, AaTX1 induces 90% decrease in I-A current amplitude. Its activity was found to be comparable to that of rAmmTX3 (alpha KTx15-3), which differs by only one conserved (R/K) amino acid in the 19th position suggesting that the difference between R19 and K19 in AaFX1 and AmmTX3, respectively, may not be critical for the toxins' effects. Molecular docking of both toxins with Kv4.3 channel is in agreement with experimental data and suggests the implication of the functional dyade K27-Y36 in toxin-channel interactions. Since AaTX1 is not highly abundant in Aa venom, it was synthesized as well as AmmTX3. Synthetic peptides, native AaTX1 and rAmmTX3 peptides showed qualitatively the same pharmacological activity. Overall, these data identify a new biologically active toxin that belongs to a family of peptides active on Kv4.3 channel. (C) 2014 Elsevier Ltd. All rights reserved