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Abstract
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The development of
lipopeptides (lipidated peptides) for vaccines
is discussed, including their role as antigens and/or adjuvants. Distinct
classes of lipopeptide architectures are covered including simple
linear and ligated constructs and lipid core peptides. The design,
synthesis, and immunological responses of the important class of glycerol-based
Toll-like receptor agonist lipopeptides such as Pam3CSK4, which contains three palmitoyl chains and a CSK4 hexapeptide sequence, and many derivatives of this model immunogenic
compound are also reviewed. Self-assembled lipopeptide structures
including spherical and worm-like micelles that have been shown to
act as vaccine agents are also described. The work discussed includes
examples of lipopeptides developed with model antigens, as well as
for immunotherapies to treat many infectious diseases including malaria,
influenza, hepatitis, COVID-19, and many others, as well as cancer
immunotherapies. Some of these have proceeded to clinical development.
The research discussed highlights the huge potential of, and diversity
of roles for, lipopeptides in contemporary and future vaccine development.
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Affiliation(s)
- Ian W Hamley
- Department of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, U.K
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Kaur A, Kaushik D, Piplani S, Mehta SK, Petrovsky N, Salunke DB. TLR2 Agonistic Small Molecules: Detailed Structure-Activity Relationship, Applications, and Future Prospects. J Med Chem 2020; 64:233-278. [PMID: 33346636 DOI: 10.1021/acs.jmedchem.0c01627] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Toll-like receptors (TLRs) are the pattern recognition receptors (PRRs) that recognize pathogen-associated molecular patterns (PAMPs) in microbial species. Among the various TLRs, TLR2 has a special place due to its ability to sense the widest repertoire of PAMPs owing to its heterodimerization with either TLR1 or TLR6, broadening its ligand diversity against pathogens. Various scaffolds are reported to activate TLR2, which include naturally occurring lipoproteins, synthetic lipopeptides, and small heterocyclic molecules. We described a detailed SAR in TLR2 agonistic scaffolds and also covered the design and chemistry for the conjugation of TLR2 agonists to antigens, carbohydrates, polymers, and fluorophores. The approaches involved in delivery of TLR2 agonists such as lipidation of antigen, conjugation to polymers, phosphonic acids, and other linkers to achieve surface adsorption, liposomal formulation, and encapsulating nanoparticles are elaborated. The crystal structure analysis and computational modeling are also included with the structural features that facilitate TLR2 activation.
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Affiliation(s)
- Arshpreet Kaur
- Department of Chemistry and Centre of Advanced Studies in Chemistry, Panjab University, Chandigarh 160014, India
| | - Deepender Kaushik
- Department of Chemistry and Centre of Advanced Studies in Chemistry, Panjab University, Chandigarh 160014, India
| | - Sakshi Piplani
- Vaxine Pty Ltd, 11 Walkley Avenue, Warradale, Australia 5046.,College of Medicine and Public Health, Flinders University, Bedford Park, Australia, 5042
| | - Surinder K Mehta
- Department of Chemistry and Centre of Advanced Studies in Chemistry, Panjab University, Chandigarh 160014, India
| | - Nikolai Petrovsky
- Vaxine Pty Ltd, 11 Walkley Avenue, Warradale, Australia 5046.,College of Medicine and Public Health, Flinders University, Bedford Park, Australia, 5042
| | - Deepak B Salunke
- Department of Chemistry and Centre of Advanced Studies in Chemistry, Panjab University, Chandigarh 160014, India.,National Interdisciplinary Centre of Vaccine, Immunotherapeutics and Antimicrobials, Panjab University, Chandigarh 160014, India
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Peterson SJ, Dave N, Kothari J. The Effects of Heme Oxygenase Upregulation on Obesity and the Metabolic Syndrome. Antioxid Redox Signal 2020; 32:1061-1070. [PMID: 31880952 DOI: 10.1089/ars.2019.7954] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Significance: Obesity is a chronic condition that is characterized by inflammation and oxidative stress with consequent cardiovascular complications of hypertension, dyslipidemia, and vascular dysfunction. Obesity-induced metabolic syndrome remains an epidemic of global proportions. Recent Advances: Gene targeting of the endothelium with a retrovirus using an endothelium-specific promoter vascular endothelium cadherin (VECAD)-HO-1 offers a potential long-term solution to adiposity by targeting the endothelium. This has resulted in improvements of both vascular function and adiposity attenuation. Critical Issues: Heme oxygenase plays an ever-increasing role in the understanding of human biology in the complex conditions of obesity and the metabolic syndrome. The heme oxygenase 1 (HO-1) system creates biliverdin/bilirubin, which functions as an antioxidant, and carbon monoxide, which has antiapoptotic properties. Future Directions: Upregulation of HO-1 has been shown to improve adiposity as well as vascular function in both animal and human studies.
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Affiliation(s)
- Stephen J Peterson
- Department of Medicine, Weill Cornell Medicine, New York, New York.,New York Presbyterian Brooklyn Methodist Hospital, Brooklyn, New York
| | - Niel Dave
- New York Presbyterian Brooklyn Methodist Hospital, Brooklyn, New York
| | - Janish Kothari
- New York Presbyterian Brooklyn Methodist Hospital, Brooklyn, New York
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Lu BL, Williams GM, Brimble MA. TLR2 agonists and their structure–activity relationships. Org Biomol Chem 2020; 18:5073-5094. [DOI: 10.1039/d0ob00942c] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We review the structure–activity relationships and synthetic studies of TLR2 agonists – important chemical targets in immunotherapy.
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Affiliation(s)
- Benjamin L. Lu
- The School of Biological Sciences
- University of Auckland
- Auckland 1010
- New Zealand
- The School of Chemical Sciences
| | - Geoffrey M. Williams
- The School of Biological Sciences
- University of Auckland
- Auckland 1010
- New Zealand
- The School of Chemical Sciences
| | - Margaret A. Brimble
- The School of Biological Sciences
- University of Auckland
- Auckland 1010
- New Zealand
- The School of Chemical Sciences
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Akazawa T, Ohashi T, Nakajima H, Nishizawa Y, Kodama K, Sugiura K, Inaba T, Inoue N. Development of a dendritic cell-targeting lipopeptide as an immunoadjuvant that inhibits tumor growth without inducing local inflammation. Int J Cancer 2014; 135:2847-56. [PMID: 24789268 DOI: 10.1002/ijc.28939] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 04/15/2014] [Indexed: 01/30/2023]
Abstract
Materials used for the past 30 years as immunoadjuvants induce suboptimal antitumor immune responses and often cause undesirable local inflammation. Some bacterial lipopeptides that act as Toll-like receptor (TLR) 2 ligands activate immune cells as immunoadjuvants and induce antitumor effects. Here, we developed a new dendritic cell (DC)-targeting lipopeptide, h11c (P2C-ATPEDNGRSFS), which uses the CD11c-binding sequence of intracellular adhesion molecule-1 to selectively and efficiently activate DCs but not other immune cells. Although the h11c lipopeptide activated DCs similarly to an artificial lipopeptide, P2C-SKKKK (P2CSK4), via TLR2 in vitro, h11c induced more effective tumor inhibition than P2CSK4 at low doses in vivo with tumor antigens. Even without tumor antigens, h11c lipopeptide significantly inhibited tumor growth and induced tumor-specific cytotoxic T cells. P2CSK4 was retained subcutaneously at the vaccination site and induced severe local inflammation in in vivo experiments. In contrast, h11c was not retained at the vaccination site and was transported into the tumor within 24 hr. The recruitment of DCs into the tumor was induced by h11c more effectively, while P2CSK4 induced the accumulation of neutrophils leading to severe inflammation at the vaccination site. Because CD11b+ cells, but not CD11c+ cells, produced neutrophil chemotactic factors such as macrophage inflammatory protein (MIP)-2 in response to stimulation with TLR2 ligands, the DC-targeting lipopeptide h11c induced less MIP-2 production by splenocytes than P2CSK4. In this study, we succeeded in developing a novel immunoadjuvant, h11c, which effectively induces antitumor activity without adverse effects such as local inflammation via the selective activation of DCs.
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Affiliation(s)
- Takashi Akazawa
- Department of Molecular Genetics, Osaka Medical Center for Cancer and Cardiovascular Diseases, Higashinari-ku, Osaka, Japan
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van Bergenhenegouwen J, Plantinga TS, Joosten LAB, Netea MG, Folkerts G, Kraneveld AD, Garssen J, Vos AP. TLR2 & Co: a critical analysis of the complex interactions between TLR2 and coreceptors. J Leukoc Biol 2013; 94:885-902. [PMID: 23990624 DOI: 10.1189/jlb.0113003] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
TLRs play a major role in microbe-host interactions and innate immunity. Of the 10 functional TLRs described in humans, TLR2 is unique in its requirement to form heterodimers with TLR1 or TLR6 for the initiation of signaling and cellular activation. The ligand specificity of TLR2 heterodimers has been studied extensively, using specific bacterial and synthetic lipoproteins to gain insight into the structure-function relationship, the minimal active motifs, and the critical dependence on TLR1 or TLR6 for activation. Different from that for specific well-defined TLR2 agonists, recognition of more complex ligands like intact microbes or molecules from endogenous origin requires TLR2 to interact with additional coreceptors. A breadth of data has been published on ligand-induced interactions of TLR2 with additional pattern recognition receptors such as CD14, scavenger receptors, integrins, and a range of other receptors, all of them important factors in TLR2 function. This review summarizes the roles of TLR2 in vivo and in specific immune cell types and integrates this information with a detailed review of our current understanding of the roles of specific coreceptors and ligands in regulating TLR2 functions. Understanding how these processes affect intracellular signaling and drive functional immune responses will lead to a better understanding of host-microbe interactions and will aid in the design of new agents to target TLR2 function in health and disease.
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Akazawa T, Inoue N, Shime H, Kodama K, Matsumoto M, Seya T. Adjuvant engineering for cancer immunotherapy: Development of a synthetic TLR2 ligand with increased cell adhesion. Cancer Sci 2010; 101:1596-603. [PMID: 20507323 PMCID: PMC11158911 DOI: 10.1111/j.1349-7006.2010.01583.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The development of effective immunoadjuvants for tumor immunotherapy is of fundamental importance. The use of Mycobacterium bovis bacillus Calmette-Guérin cell wall skeleton (BCG-CWS) in tumor immunotherapy has been examined in various clinical applications. Because BCG-CWS is a macromolecule that cannot be chemically synthesized, the development of an alternative synthetic molecule is necessary to ensure a constant supply of adjuvant. In the present study, a new adjuvant was designed based on the structure of macrophage-activating lipopeptide (MALP)-2, which is a Toll-like receptor (TLR)-2 ligand similar to BCG-CWS. Macrophage-activating lipopeptide-2, [S-(2,3-bispalmitoyloxypropyl)Cys (P2C) - GNNDESNISFKEK], originally identified in a Mycoplasma species, is a lipopeptide that can be chemically synthesized. A MALP-2 peptide was substituted with a functional motif, RGDS, creating a novel molecule named P2C-RGDS. RGDS was selected because its sequence constitutes an integrin-binding motif and various integrins are expressed in immune cells including dendritic cells (DCs). Thus, this motif adds functionality to the ligand. P2C-RGDS activated DCs and splenocytes more efficiently than MALP-2 over short incubation times in vitro, and the RGDS motif contributed to their activation. Furthermore, P2C-RGDS showed higher activity than MALP-2 in inducing migration of DCs to draining lymph node, and in inhibiting tumor growth in vivo. This process of designing and developing synthetic adjuvants has been named "adjuvant engineering," and the evaluation and improvement of P2C-RGDS constitutes a first step in the development of stronger synthetic adjuvants in the future.
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Affiliation(s)
- Takashi Akazawa
- Department of Molecular Genetics, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan.
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Kimbrell MR, Warshakoon H, Cromer JR, Malladi S, Hood JD, Balakrishna R, Scholdberg TA, David SA. Comparison of the immunostimulatory and proinflammatory activities of candidate Gram-positive endotoxins, lipoteichoic acid, peptidoglycan, and lipopeptides, in murine and human cells. Immunol Lett 2008; 118:132-41. [PMID: 18468694 DOI: 10.1016/j.imlet.2008.03.009] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2008] [Revised: 03/13/2008] [Accepted: 03/21/2008] [Indexed: 01/07/2023]
Abstract
The role of lipopolysaccharide (LPS) in the pathogenesis of Gram-negative septic shock is well established. The corresponding proinflammatory and immunostimulatory molecule(s) on the Gram-positive bacteria is less well understood, and its identification and characterization would be a key prerequisite in designing specific sequestrants of the Gram-positive endotoxin(s). We report in this paper the comparison of NF-kappaB-, cytokine- and chemokine-inducing activities of the TLR2 ligands, lipoteichoic acid (LTA), peptidoglycan (PGN), and lipopeptides, to LPS, a prototype TLR4 agonist, in murine macrophage cell-lines as well as in human blood. In murine cells, di- and triacyl liopopeptides are equipotent in their NF-kappaB inducing activity relative to LPS, but elicit much lower proinflammatory cytokines. However, both LPS and the lipopeptides potently induce the secretion of a pattern of chemokines that is suggestive of the engagement of a TLR4-independent TRIF pathway. In human blood, although the lipopeptides induce p38 MAP kinase phosphorylation and CD11b upregulation in granulocytes at ng/ml concentrations, they do not elicit proinflammatory cytokine production even at very high doses; LTA, however, activates neutrophils and induces cytokine secretion, although its potency is considerably lower than that of LPS, presumably due to its binding to plasma proteins. We conclude that, in human blood, the pattern of immunostimulation and proinflammatory mediator production elicited by LTA parallels that of LPS.
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Boato F, Thomas RM, Ghasparian A, Freund-Renard A, Moehle K, Robinson JA. Synthetic virus-like particles from self-assembling coiled-coil lipopeptides and their use in antigen display to the immune system. Angew Chem Int Ed Engl 2008; 46:9015-8. [PMID: 17935102 DOI: 10.1002/anie.200702805] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Francesca Boato
- Department of Chemistry, University of Zurich, 8057-Zurich, Switzerland
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Boato F, Thomas R, Ghasparian A, Freund-Renard A, Moehle K, Robinson J. Synthetic Virus-Like Particles from Self-Assembling Coiled-Coil Lipopeptides and Their Use in Antigen Display to the Immune System. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200702805] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Voss S, Ulmer A, Jung G, Wiesmüller KH, Brock R. The activity of lipopeptide TLR2 agonists critically depends on the presence of solubilizers. Eur J Immunol 2007; 37:3489-98. [DOI: 10.1002/eji.200737537] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Gust AA, Biswas R, Lenz HD, Rauhut T, Ranf S, Kemmerling B, Götz F, Glawischnig E, Lee J, Felix G, Nürnberger T. Bacteria-derived peptidoglycans constitute pathogen-associated molecular patterns triggering innate immunity in Arabidopsis. J Biol Chem 2007; 282:32338-48. [PMID: 17761682 DOI: 10.1074/jbc.m704886200] [Citation(s) in RCA: 192] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pathogen-associated molecular pattern (PAMP)-triggered immunity constitutes the primary plant immune response that has evolved to recognize invariant structures of microbial surfaces. Here we show that Gram-positive bacteria-derived peptidoglycan (PGN) constitutes a novel PAMP of immune responses in Arabidopsis thaliana. Treatment with PGN from Staphylococcus aureus results in the activation of plant responses, such as medium alkalinization, elevation of cytoplasmic calcium concentrations, nitric oxide, and camalexin production and the post-translational induction of MAPK activities. Microarray analysis performed with RNA prepared from PGN-treated Arabidopsis leaves revealed enhanced transcript levels for 236 genes, many of which are also altered upon administration of flagellin. Comparison of cellular responses after treatment with bacteria-derived PGN and structurally related fungal chitin indicated that both PAMPs are perceived via different perception systems. PGN-mediated immune stimulation in Arabidopsis is based upon recognition of the PGN sugar backbone, while muramyl dipeptide, which is inactive in this plant, triggers immunity-associated responses in animals. PGN adds to the list of PAMPs that induce innate immune programs in both plants and animals. However, we propose that PGN perception systems arose independently in both lineages and are the result of convergent evolution.
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Affiliation(s)
- Andrea A Gust
- Center for Plant Molecular Biology, Plant Biochemistry, and Microbial Genetics, University of Tübingen, 72076 Tübingen, Germany.
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Buwitt-Beckmann U, Heine H, Wiesmüller KH, Jung G, Brock R, Ulmer AJ. Lipopeptide structure determines TLR2 dependent cell activation level. FEBS J 2006; 272:6354-64. [PMID: 16336272 DOI: 10.1111/j.1742-4658.2005.05029.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Bacterial lipoproteins/peptides are composed of di-O-acylated-S-(2,3-dihydroxypropyl)-cysteinyl residues N-terminally coupled to distinct polypeptides, which can be N-acylated with a third fatty acid. Using a synthetic lipopeptide library we characterized the contribution of the lipid portion to the TLR2 dependent pattern recognition. We found that the two ester bound fatty acid length threshold is beyond eight C atoms because almost no response was elicited by cellular challenge with analogues carrying shorter acyl chains in HEK293 cells expressing recombinant human TLR2. In contrast, the amide bound fatty acid is of lesser importance. While two ester-bound palmitic acids mediate a high stimulatory activity of the respective analogue, a lipopeptide carrying one amide-bound and another ester-bound palmitic acid molecule was inactive. In addition, species specific LP recognition through murine and human TLR2 depended on the length of the two ester bound fatty acid chains. In conclusion, our results indicate the responsibility of both ester bound acyl chains but not of the amide bound fatty acid molecule for the TLR dependent cellular recognition of canonical triacylated LP, as well as a requirement for a minimal acyl chain length. Thus they might support the explanation of specific immuno-stimulatory potentials of different microorganisms and provide a basis for rational design of TLR2 specific adjuvants mediating immune activation to distinct levels.
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Affiliation(s)
- Ute Buwitt-Beckmann
- Department of Immunology and Cell Biology, Research Center Borstel, Borstel, Germany
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