Direct peptide lipidation through thiol-ene coupling enables rapid synthesis and evaluation of self-adjuvanting vaccine candidates

Toll-like receptor agonist lipopeptides self-assemble into distinct nanostructures

The self-assembled structure of toll-like receptor agonist lipopeptides containing the CSK4 peptide sequence is examined in aqueous solution. A remarkable dependence of morphology on the number of attached hexadecyl lipid chains is demonstrated, with spherical micelle structures for mono- and di-lipidated structures observed, but flexible wormlike micelles for the homologue containing three lipid chains. The distinct modes of assembly may have an important influence on the bioactivity of this class of lipopeptide.

NKT cell-dependent glycolipid-peptide vaccines with potent anti-tumour activity

Glycolipid–peptide conjugates designed to release vaccine components within target cells ensuring potent CD1d dependent T cell responses.

It is known that T cells can eliminate tumour cells through recognition of unique or aberrantly expressed antigens presented as peptide epitopes by major histocompatibility complex (MHC) molecules on the tumour cell surface. With recent advances in defining tumour-associated antigens, it should now be possible to devise therapeutic vaccines that expand specific populations of anti-tumour T cells. However there remains a need to develop simpler efficacious synthetic vaccines that possess clinical utility. We present here the synthesis and analysis of vaccines based on conjugation of MHC-binding peptide epitopes to α-galactosylceramide, a glycolipid presented by the nonpolymorphic antigen-presenting molecule CD1d to provoke the stimulatory activity of type I natural killer T (NKT) cells. The chemical design incorporates an enzymatically cleavable linker that effects controlled release of the active components in vivo. Chemical and biological analysis of different linkages with different enzymatic targets enabled selection of a synthetic vaccine construct with potent therapeutic anti-tumour activity in mice, and marked in vitro activity in human blood.

Covalent bond or noncovalent bond: a supramolecular strategy for the construction of chemically synthesized vaccines

A novel noncovalent strategy to construct chemically synthesized vaccines has been designed to trigger a robust immune response and to dramatically improve the efficiency of vaccine preparation. Glycosylated MUC1 tripartite vaccines were constructed through host-guest interactions with cucurbit[8]uril. These vaccines elicited high levels of IgG antibodies that were recognized by transformed cells and induced the secretion of cytokines. The antisera also mediated complement-dependent cytotoxicity. This noncovalent strategy with good suitability, scalability, and feasibility can be applied as a universal strategy for the construction of chemically synthesized vaccines.

Chemical synthesis of the ATAD2 bromodomain

Due to the emerging importance of the bromodomain binding region in the study of epigenetic effectors and the vast implications for a wide variety of human disease, the bromodomain region of human ATPase family AAA+ (ATPases associated with diverse cellular activities) domain-containing protein 2 (ATAD2) was targeted for chemical synthesis. The ATAD2 bromodomain (130 aa) was divided into five strategic fragments to be assembled using native chemical ligation with a focus on maximal convergency and efficiency. The fragments were assembled with one cysteine and three thioleucine ligations, unveiling the native alanine and leucine amino acids at the ligation points following metal-free dethiylation. Synthetic highlights of the study are a photolabile dimethoxynitrobenzyl-protected glutamic acid side chain used to impede hydrolysis of the C-terminal Glu-thioester, a thiazolidine-protected thioleucine, and an efficient assembly of three fragments in a single reaction vessel with dual-mode kinetic-standard chemical ligation. With a focus on material throughput and convergency, the five peptide fragments were assembled into the native ATAD2 bromodomain region with a total of three HPLC events in 8% overall yield from the fragments.

“Click” reactions: a versatile toolbox for the synthesis of peptide-conjugates

Peptides that comprise the functional subunits of proteins have been conjugated to versatile materials (biomolecules, polymers, surfaces and nanoparticles) in an effort to modulate cell responses, specific binding affinity and/or self-assembly behavior.