Partially Modified Retro-Inverso Pseudopeptides as Non-natural Ligands for the Human Class I Histocompatibility Molecule HLA-A2

Abstract

Syntheses of a series of partially modified retro-inverso analogues of the antigenic peptide M58-66 derived from the influenza virus matrix protein are reported. The retro-inverso modification phi(NH-CO) was obtained by replacement of two successive amino acid residues with a 2-substituted malonate derivative and gem-diaminoalkyl residue. The resulting compounds 1-8 were tested for their binding to the human histocompatibility class I molecule HLA-A2 in an assembly assay using lysates of peptide transporter-deficient cells T2. Specific peptide-dependent HLA-A2 assembly was revealed by an enzyme-linked immunosorbent assay. Significant HLA-A2 assembly was detected in the presence of analogues [gGly58-(S)mLeu59]-M58-66 (1a), [gGly61-(R,S)mPhe62]M58-66 (4), [gVal63-(R,S)mPhe64]M58-66 (6), and [gPhe64-(R,S)mAla65]M58-66 (7). The introduction of the retro-inverso modification between P2-P3, P3-P4, P5-P6, and P8-P9 (compounds 2, 3, 5, and 8, respectively) however led to a dramatic reduction in peptide binding to HLA-A2. Interestingly, compound 1a which contains modification between P1-P2 was found to be the most potent analogue, being able to retain the original HLA-A2 binding profile of the parent peptide M58-66. Taken together, these results and recent binding data obtained in the context of murine MHC class I molecule H-2Kd suggest that the incorporation of peptide bond surrogates in MHC class I-restricted epitopes is a useful approach to design molecules having both increased stability and high MHC-binding capacity. Depending on their agonist or antagonist effects at the T-cell receptor, such non-natural MHC ligands are likely to find many applications in the development of peptide-based vaccines or as potential therapeutic agents in the treatment of allergies and autoimmune diseases.

Functional and Structural Characteristics of NY-ESO-1-related HLA A2-restricted Epitopes and the Design of a Novel Immunogenic Analogue

“…Several studies have incorporated nonnatural amino acids in peptidic structures to improve compound stability and maintain T cell cross-reactivity. For example, some studies have used nonnatural amino acids with modified side chains that approximate the natural amino acid (10, 11) or by modifying peptide bonds by introducing ␤-amino acids (12, 13), reducing peptide bonds from the natural amine bonds to aminomethylene (14, 15) or generation of partially modified retro-inverso pseudopeptides (8,16,17).The search for appropriate TAA for vaccination and immunotherapy has extended to several classes of tumor antigens. Ideally such candidates are expressed solely in cancerous tissue and are essential for the malignant phenotype; however, few examples of such antigens exist.…”

“…Such engineering may include optimizing target MHC class I binding by substituting key residues with more appropriate anchor residues. In addition, peptide-based therapeutics can be engineered to improve formulation and storage properties, and strategies exist to protect labile peptide bonds by incorporating nonpeptidic structures (7)(8)(9)(10)(11). Several studies have incorporated nonnatural amino acids in peptidic structures to improve compound stability and maintain T cell cross-reactivity.…”

“…Several studies have incorporated nonnatural amino acids in peptidic structures to improve compound stability and maintain T cell cross-reactivity. For example, some studies have used nonnatural amino acids with modified side chains that approximate the natural amino acid (10,11) or by modifying peptide bonds by introducing ␤-amino acids (12,13), reducing peptide bonds from the natural amine bonds to aminomethylene (14,15) or generation of partially modified retro-inverso pseudopeptides (8,16,17).…”

A New Generation of Melan-A/MART-1 Peptides That Fulfill Both Increased Immunogenicity and High Resistance to Biodegradation: Implication for Molecular Anti-Melanoma Immunotherapy

“…A superagonist variant of the nonameric Melan-A [27][28][29][30][31][32][33][34][35] peptide has been shown to elicit an enhanced anti-melanoma CD8 ϩ CTL response (9). We have recently undertaken clinical trials of peptide vaccination using the decameric analog Melan-A 26 -35 A27L (ELAGIGILTV).…”

The partial retro–inverso modification: A road traveled together

“…35 In another study Guichard and coworkers reported the preparation of a series of PMRI analogs of the influenza matrix peptide 58 -66 [M(58 -66)] known to be a human leukocyte antigen (HLA)-A2-restricted epitope that binds preferentially nonapeptides with Leu, Met, or Ile in position P2 and Val, Leu, or Ile in position P9. 36 PMRI pseudopeptide [Gly 58 ⌿ (NH-CO)Leu 59 ]M(58 -66) was able to stabilize HLA-A2 at a concentration of 10 nM and was found to be more effective than the wild-type sequence in stimulating CD8 ϩ CTL to secrete interferon-␥ (INF-␥) and synthesize tumor necrosis factor (TNF)-␣ mRNA, cytokines involved in antiviral and antitumor responses. 37 Recently, Ben-Yedidia and coworkers reported that intranasal immunization of mice with an ovalbuminconjugated RI analog of the protective B-cell epitope hemagglutinin (HA)[91-108] from influenza HA, in the presence of cholera toxin as adjuvant, produced strong systemic and mucosal antibody responses.…”