ADP-ribose (ADPr) readers are essential components of ADP-ribosylation signaling, which regulates genome maintenance and immunity. The identification and discrimination between monoADPr (MAR) and... Show moreADP-ribose (ADPr) readers are essential components of ADP-ribosylation signaling, which regulates genome maintenance and immunity. The identification and discrimination between monoADPr (MAR) and polyADPr (PAR) readers is difficult because of a lack of suitable affinity-enrichment reagents. We synthesized well-defined ADPr probes and used these for affinity purifications combined with relative and absolute quantitative mass spectrometry to generate proteome-wide MAR and PAR interactomes, including determination of apparent binding affinities. Among the main findings, MAR and PAR readers regulate various common and distinct processes, such as the DNA-damage response, cellular metabolism, RNA trafficking, and transcription. We monitored the dynamics of PAR interactions upon induction of oxidative DNA damage and uncovered the mechanistic connections between ubiquitin signaling and ADP-ribosylation. Taken together, chemical biology enables exploration of MAR and PAR readers using interaction proteomics. Furthermore, the generated MAR and PAR interaction maps significantly expand our current understanding of ADPr signaling. Show less
Reijneveld, J.F.; Marino, L.; Cao, T.P.; Cheng, T.Y.; Dam, D.; Shahine, A.; ... ; Rhijn, I. van 2021
Whereas proteolytic cleavage is crucial for peptide presentation by classical major histocompatibility complex (MHC) proteins to T cells, glycolipids presented by CD1 molecules are typically... Show moreWhereas proteolytic cleavage is crucial for peptide presentation by classical major histocompatibility complex (MHC) proteins to T cells, glycolipids presented by CD1 molecules are typically presented in an unmodified form. However, the mycobacterial lipid antigen mannosyl-β1-phosphomycoketide (MPM) may be processed through hydrolysis in antigen presenting cells, forming mannose and phosphomycoketide (PM). To further test the hypothesis that some lipid antigens are processed, and to generate antigens that lead to defined epitopes for future tuberculosis vaccines or diagnostic tests, we aimed to create hydrolysis-resistant MPM variants that retain their antigenicity. Here, we designed and tested three different, versatile synthetic strategies to chemically stabilize MPM analogs. Crystallographic studies of CD1c complexes with these three new MPM analogs showed anchoring of the lipid tail and phosphate group that is highly comparable to nature-identical MPM, with considerable conformational flexibility for the mannose head group. MPM-3, a difluoromethylene-modified version of MPM that is resistant to hydrolysis showed altered recognition by cells, but not by CD1c proteins, supporting the cellular antigen processing hypothesis. Furthermore, the synthetic analogs elicited T cell responses that were cross-reactive with nature-identical MPM, fulfilling important requirements for future clinical use. Show less
Luscher, B.; Ahel, I.; Altmeyer, M.; Ashworth, A.; Bai, P.T.; Chang, P.; ... ; Ziegler, M. 2021
ADP-ribosylation, a modification of proteins, nucleic acids, and metabolites, confers broad functions, including roles in stress responses elicited, for example, by DNA damage and viral infection... Show moreADP-ribosylation, a modification of proteins, nucleic acids, and metabolites, confers broad functions, including roles in stress responses elicited, for example, by DNA damage and viral infection and is involved in intra- and extracellular signaling, chromatin and transcriptional regulation, protein biosynthesis, and cell death. ADP-ribosylation is catalyzed by ADP-ribosyltransferases (ARTs), which transfer ADP-ribose from NAD(+) onto substrates. The modification, which occurs as mono- or poly-ADP-ribosylation, is reversible due to the action of different ADP-ribosylhydrolases. Importantly, inhibitors of ARTs are approved or are being developed for clinical use. Moreover, ADP-ribosylhydrolases are being assessed as therapeutic targets, foremost as antiviral drugs and for oncological indications. Due to the development of novel reagents and major technological advances that allow the study of ADP-ribosylation in unprecedented detail, an increasing number of cellular processes and pathways are being identified that are regulated by ADP-ribosylation. In addition, characterization of biochemical and structural aspects of the ARTs and their catalytic activities have expanded our understanding of this protein family. This increased knowledge requires that a common nomenclature be used to describe the relevant enzymes. Therefore, in this viewpoint, we propose an updated and broadly supported nomenclature for mammalian ARTs that will facilitate future discussions when addressing the biochemistry and biology of ADP-ribosylation. This is combined with a brief description of the main functions of mammalian ARTs to illustrate the increasing diversity of mono- and poly-ADP-ribose mediated cellular processes. Show less
Liu, Q.; Knobloch, G.; Voorneveld, J.; Meeuwenoord, N.J.; Overkleeft, H.S.; Marel, G.A. van der; ... ; Filippov, D.V. 2021
ADP-ribosylation is a pivotal post-translational modification that mediates various important cellular processes producing negatively charged biopolymer, poly (ADP-ribose), the functions of which... Show moreADP-ribosylation is a pivotal post-translational modification that mediates various important cellular processes producing negatively charged biopolymer, poly (ADP-ribose), the functions of which need further elucidation. Toward this end, the availability of well-defined ADP-ribose (ADPr) oligomers in sufficient quantities is a necessity. In this work, we demonstrate the chemical synthesis of linear ADPr oligomers of defined, increasing length using a modified solid phase synthesis method. An advanced phosphoramidite building block temporarily protected with the base sensitive Fm-group was designed and implemented in the repeating pyrophosphate formation via a P(v)-P(iii) coupling procedure on Tentagel solid support. Linear ADPr oligomers up to a pentamer were successfully synthesized and their affinity for the poly-(ADP-ribose)-binding macrodomain of the human oncogenic helicase and chromatin remodeling enzyme ALC1 was determined. Our data reveal a length-dependent binding manner of the nucleic acid, with larger ADPr oligomers exhibiting higher binding enthalpies for ALC1, illustrating how the activity of this molecular machine is gated by PAR. Show less
Poly(ADP-ribosyl)ation (PAR) is a versatile and complex posttranslational modification composed of repeating units of ADP-ribose arranged into linear or branched polymers. This scaffold is linked... Show morePoly(ADP-ribosyl)ation (PAR) is a versatile and complex posttranslational modification composed of repeating units of ADP-ribose arranged into linear or branched polymers. This scaffold is linked to the regulation of many of cellular processes including the DNA damage response, alteration of chromatin structure and Wnt signalling. Despite decades of research, the principles and mechanisms underlying all steps of PAR removal remain actively studied. In this work, we synthesise well-defined PAR branch point molecules and demonstrate that PARG, but not ARH3, can resolve this distinct PAR architecture. Structural analysis of ARH3 in complex with dimeric ADP-ribose as well as an ADP-ribosylated peptide reveal the molecular basis for the hydrolysis of linear and terminal ADP-ribose linkages. We find that ARH3-dependent hydrolysis requires both rearrangement of a catalytic glutamate and induction of an unusual, square-pyramidal magnesium coordination geometry. Show less
Wall teichoic acids (WTAs) are important components of the cell wall of the opportunistic Gram-positive bacterium Staphylococcus aureus. WTAs are composed of repeating ribitol phosphate (RboP)... Show moreWall teichoic acids (WTAs) are important components of the cell wall of the opportunistic Gram-positive bacterium Staphylococcus aureus. WTAs are composed of repeating ribitol phosphate (RboP) residues that are decorated with d-alanine and N-acetyl-d-glucosamine (GlcNAc) modifications, in a seemingly random manner. These WTA-modifications play an important role in shaping the interactions of WTA with the host immune system. Due to the structural heterogeneity of WTAs, it is impossible to isolate pure and well-defined WTA molecules from bacterial sources. Therefore, here synthetic chemistry to assemble a broad library of WTA-fragments, incorporating all possible glycosylation modifications (alpha-GlcNAc at the RboP C4; beta-GlcNAc at the RboP C4; beta-GlcNAc at the RboP C3) described for S. aureus WTAs, is reported. DNA-type chemistry, employing ribitol phosphoramidite building blocks, protected with a dimethoxy trityl group, was used to efficiently generate a library of WTA-hexamers. Automated solid phase syntheses were used to assemble a WTA-dodecamer and glycosylated WTA-hexamer. The synthetic fragments have been fully characterized and diagnostic signals were identified to discriminate the different glycosylation patterns. The different glycosylated WTA-fragments were used to probe binding of monoclonal antibodies using WTA-functionalized magnetic beads, revealing the binding specificity of these WTA-specific antibodies and the importance of the specific location of the GlcNAc modifications on the WTA-chains. Show less
Background: Therapeutic vaccines based on synthetic long peptides (SLPs) have a great potential for immunotherapy of cancer patients as these SLPs include both human leukocyte antigen (HLA) class I... Show moreBackground: Therapeutic vaccines based on synthetic long peptides (SLPs) have a great potential for immunotherapy of cancer patients as these SLPs include both human leukocyte antigen (HLA) class I and II epitopes and no patient selection for HLA types is required. The antigen-induced immune response can be strengthened with immune stimulating additives. Amplivant (AV) is a synthetic Toll-like receptor 2 ligand which can be directly conjugated to tumor peptide antigens. In preclinical studies, AV-conjugation to antigens led to both enhanced antigen presentation by dendritic cells and T-cell priming and caused superior induction of effective anti-tumor responses. Moreover, AV-conjugated SLPs showed a 100 times higher immune response compared to unconjugated SLP. The current study is a first-in-human trial to investigate safety and immunogenicity of AV-conjugated human papillomavirus (HPV)16-SLPs. Methods: A dose escalation phase I trial was performed in 24 patients with HPV16 positive (pre-) malignant lesions. AV was conjugated to two SLPs derived from the most immunodominant regions of the HPV16 E6 oncoprotein. Four dose groups (1, 5, 20 or 50 μg of each peptide) in 6 patients each were studied. The vaccine was injected three times intradermally in DMSO / water with a three-week interval. Adverse events (AE) were collected according to CTCAE v4.0 up to 26 weeks. Peptide-specific T-cell immune responses were determined in blood samples taken before and after vaccination using complementary immunological assays (proliferation assay, IFNγ-ELISPOT and cytokine bead array). Results: Toxicity after three AV-conjugated HPV16-SLP vaccinations was limited to CTCAE grade 1 or 2, with predominantly inflammation at the vaccination site and sometimes flu-like symptoms, which generally resolved within one day. Dose increase resulted from no AE in the lowest dose group to mild/moderate AE in all vaccinated persons in the highest dose group. In the lowest dose group, minor vaccine-induced T-cell responses were observed in three of six vaccinated persons. In the highest dose group, all patients displayed a strong HPV16-specific T-cell response after vaccination. The induced T-cell response against HPV16 lasted until the end of the trial. Conclusions: This first-in-human study showed that AV conjugated to SLPs can safely be used as an intradermal therapeutic vaccine. AV-conjugated HPV16-SLP was able to induce robust HPV16-specific T-cell immunity in patients treated for HPV16 positive (pre-) malignancies without any other vaccine adjuvant or formulation. Increase in dose resulted in both a higher number of mild adverse events as well as stronger T-cell immunity. Clinical trial information: NCT02821494.Show less
ADP-ribosylation (ADPr), as a post-translational modification, plays a crucial role in DNA-repair, immunity and many other cellular and physiological processes. Serine is the main acceptor for ADPr... Show moreADP-ribosylation (ADPr), as a post-translational modification, plays a crucial role in DNA-repair, immunity and many other cellular and physiological processes. Serine is the main acceptor for ADPr in DNA damage response, whereas the physiological impact of less common ADPr-modifications of cysteine and threonine side chains is less clear. Generally, gaining molecular insights into ADPr recognition and turn-over is hampered by the availability of homogeneous, ADP-ribosylated material, such as mono-ADP-ribosylated (MARylated) peptides. Here, a new and efficient solid-phase strategy for the synthesis of Ser-, Thr- and Cys-MARylated peptides is described. ADP-ribosylated cysteine, apart from being a native post-translational modification in its own right, proved to be suitable as a stabile bioisostere for ADP-ribosylated serine making it a useful tool to further biochemical research on serine ADP-ribosylation. In addition, it was discovered that the Streptococcus pyogenes encoded protein, SpyMacroD, acts as a Cys-(ADP-ribosyl) hydrolase. Show less
ADP-ribosylation (ADPr), as a post-translational modification, plays a crucial role in DNA-repair, immunity and many other cellular and physiological processes. Serine is the main acceptor for ADPr... Show moreADP-ribosylation (ADPr), as a post-translational modification, plays a crucial role in DNA-repair, immunity and many other cellular and physiological processes. Serine is the main acceptor for ADPr in DNA damage response, whereas the physiological impact of less common ADPr-modifications of cysteine and threonine side chains is less clear. Generally, gaining molecular insights into ADPr recognition and turn-over is hampered by the availability of homogeneous, ADP-ribosylated material, such as mono-ADP-ribosylated (MARylated) peptides. Here, a new and efficient solid-phase strategy for the synthesis of Ser-, Thr- and Cys-MARylated peptides is described. ADP-ribosylated cysteine, apart from being a native post-translational modification in its own right, proved to be suitable as a stabile bioisostere for ADP-ribosylated serine making it a useful tool to further biochemical research on serine ADP-ribosylation. In addition, it was discovered that the Streptococcus pyogenes encoded protein, SpyMacroD, acts as a Cys-(ADP-ribosyl) hydrolase. Show less
Madern, J.M.; Kim, R.Q.; Misra, M.; Dikic, I.; Zhang, Y.; Ovaa, H.; ... ; Noort, G.J.V. van 2021
4H-Cyclopenta[def]phenanthrene (CPP) is a valuable building block in the production of photoactive polymers, which find use in a wide range of organic electronic applications. Of particular... Show more4H-Cyclopenta[def]phenanthrene (CPP) is a valuable building block in the production of photoactive polymers, which find use in a wide range of organic electronic applications. Of particular importance is their use in the development of blue-colored, organic light-emitting diodes (OLEDs), which remains a challenge in the field. Unfortunately, commercial sources and synthetic procedures known in the literature are unable to provide enough CPP for large scale implementation. Herein, we report on the development of a novel, gram-scale synthesis of CPP in three steps, starting from pyrene. The key steps in our methodology are the ring contraction of pyrene-4,5-dione to oxoCPP in a single step, as well as the direct reduction of oxoCPP to CPP. Apart from the small number of synthetic steps, our methodology benefits from the use of relatively non-hazardous reagents, together with optimized purification procedures, making CPP accessible in useful quantities. Show less
Hansen, T.; Vermeeren, P.; Yoshisada, R.; Filippov, D.V.; Marel, G.A. van der; Codee, J.D.C.; Hamlin, T.A. 2021
We have quantum chemically studied the Lewis acid-catalyzed epoxide ring-opening reaction of cyclohexene epoxide by MeZH (Z = O, S, and NH) using relativistic dispersion-corrected density... Show moreWe have quantum chemically studied the Lewis acid-catalyzed epoxide ring-opening reaction of cyclohexene epoxide by MeZH (Z = O, S, and NH) using relativistic dispersion-corrected density functional theory. We found that the reaction barrier of the Lewis acid-catalyzed epoxide ring-opening reactions decreases upon ascending in group 1 along the series Cs+ > Rb+ > K+ > Na+ > Li+ > H+. Our activation strain and Kohn-Sham molecular orbital analyses reveal that the enhanced reactivity of the Lewis acid-catalyzed ring-opening reaction is caused by the reduced steric (Pauli) repulsion between the filled orbitals of the epoxide and the nucleophile, as the Lewis acid polarizes the filled orbitals of the epoxide more efficiently away from the incoming nucleophile. Furthermore, we established that the regioselectivity of these ring-opening reactions is, aside from the "classical" strain control, also dictated by a hitherto unknown mechanism, namely, the steric (Pauli) repulsion between the nucleophile and the substrate, which could be traced back to the asymmetric orbital density on the epoxide. In all, this work again demonstrates that the concept of Pauli-lowering catalysis is a general phenomenon. Show less
Kim, R.Q.; Misra, M.; Gonzalez, A.; Tomaskovic, I.; Shin, D.; Schindelin, H.; ... ; Noort, G.J.V. van 2020
Legionnaires' disease is caused by infection with the intracellularly replicating Gram-negative bacterium Legionella pneumophila. This pathogen uses an unconventional way of ubiquitinating host... Show moreLegionnaires' disease is caused by infection with the intracellularly replicating Gram-negative bacterium Legionella pneumophila. This pathogen uses an unconventional way of ubiquitinating host proteins by generating a phosphoribosyl linkage between substrate proteins and ubiquitin by making use of an ADPribosylated ubiquitin (Ub(ADPr)) intermediate. The family of SidE effector enzymes that catalyze this reaction is counteracted by Legionella hydrolases, which are called Dups. This unusual ubiquitination process is important for Legionella proliferation and understanding these processes on a molecular level might prove invaluable in finding new treatments. Herein, a modular approach is used for the synthesis of triazole-linked Ub(ADPr), and analogues thereof, and their affinity towards the hydrolase DupA is determined and hydrolysis rates are compared to natively linked Ub(ADPr). The inhibitory effects of modified Ub on the canonical eukaryotic E1-enzyme Uba1 are investigated and rationalized in the context of a high-resolution crystal structure reported herein. Finally, it is shown that synthetic Ub(ADPr) analogues can be used to effectively pull-down overexpressed DupA from cell lysate. Show less
Ende, T.C. van den; Heuts, J.M.M.; Gential, G.P.P.; Visser, M.; Graaff, M.J. van de; Ho, N.I.; ... ; Filippov, D.V. 2020
Synthetic vaccines, based on antigenic peptides that comprise MHC-I and MHC-II T-cell epitopes expressed by tumors, show great promise for the immunotherapy of cancer. For optimal immunogenicity,... Show moreSynthetic vaccines, based on antigenic peptides that comprise MHC-I and MHC-II T-cell epitopes expressed by tumors, show great promise for the immunotherapy of cancer. For optimal immunogenicity, the synthetic peptides (SPs) should be adjuvanted with suitable immunostimulatory additives. Previously, we have shown that improved immunogenicity in vivo is obtained with vaccine modalities in which an SP is covalently connected to an adjuvanting moiety, typically a ligand to Toll-like receptor 2 (TLR2). SPs were covalently attached to UPam, which is a derivative of the classic TLR2 ligand Pam(3)CysSK(4). A disadvantage of the triply palmitoylated UPam is its high lipophilicity, which precludes universal adoption of this adjuvant for covalent modification of various antigenic peptides as it renders the synthetic vaccine insoluble in several cases. Here, we report a novel conjugatable TLR2 ligand, mini-UPam, which contains only one palmitoyl chain, rather than three, and therefore has less impact on the solubility and other physicochemical properties of a synthetic peptide. In this study, we used SPs that contain the clinically relevant neoepitopes identified in a melanoma patient who completely recovered after T-cell therapy. Homogeneous mini-UPam-SP conjugates have been prepared in good yields by stepwise solid-phase synthesis that employed a mini-UPam building block pre-prepared in solution and the standard set of Fmoc-amino acids. The immunogenicity of the novel mini-UPam-SP conjugates was demonstrated by using the cancer patient's T-cells. Show less
Ende, T.C. van den; Heuts, J.M.M.; Gential, G.P.P.; Visser, M.; Graaff, M.J. van de; Ho, N.I.; ... ; Filippov, D.V. 2020
Synthetic vaccines, based on antigenic peptides that comprise MHC−I and MHC‐II T‐cell epitopes expressed by tumors, show great promise for the immunotherapy of cancer. For optimal immunogenicity,... Show moreSynthetic vaccines, based on antigenic peptides that comprise MHC−I and MHC‐II T‐cell epitopes expressed by tumors, show great promise for the immunotherapy of cancer. For optimal immunogenicity, the synthetic peptides (SPs) should be adjuvanted with suitable immunostimulatory additives. Previously, we have shown that improved immunogenicity in vivo is obtained with vaccine modalities in which an SP is covalently connected to an adjuvanting moiety, typically a ligand to Toll‐like receptor 2 (TLR2). SPs were covalently attached to UPam, which is a derivative of the classic TLR2 ligand Pam3CysSK4. A disadvantage of the triply palmitoylated UPam is its high lipophilicity, which precludes universal adoption of this adjuvant for covalent modification of various antigenic peptides as it renders the synthetic vaccine insoluble in several cases. Here, we report a novel conjugatable TLR2 ligand, mini‐UPam, which contains only one palmitoyl chain, rather than three, and therefore has less impact on the solubility and other physicochemical properties of a synthetic peptide. In this study, we used SPs that contain the clinically relevant neoepitopes identified in a melanoma patient who completely recovered after T‐cell therapy. Homogeneous mini‐UPam‐SP conjugates have been prepared in good yields by stepwise solid‐phase synthesis that employed a mini‐UPam building block pre‐prepared in solution and the standard set of Fmoc‐amino acids. The immunogenicity of the novel mini‐UPam‐SP conjugates was demonstrated by using the cancer patient's T‐cells. Show less
Mannose-6-phosphate (M6P) is recognized by the mannose-6-phosphate receptor and plays an important role in the transport of cargo to the endosomes, making it an attractive tool to improve endosomal... Show moreMannose-6-phosphate (M6P) is recognized by the mannose-6-phosphate receptor and plays an important role in the transport of cargo to the endosomes, making it an attractive tool to improve endosomal trafficking of vaccines. We describe herein the assembly of peptide antigen conjugates carrying clusters of mannose-6-C-phosphonates (M6Po). The M6Po's are stable M6P mimics that are resistant to cleavage of the phosphate group by endogenous phosphatases. Two different strategies for the incorporation of the M6Po clusters in the conjugate have been developed: the first relies on a "post-assembly" click approach employing an M6Po bearing an alkyne functionality; the second hinges on an M6PoC-glycoside amino acid building block that can be used in solid-phase peptide synthesis. The generated conjugates were further equipped with a TLR7 ligand to stimulate dendritic cell (DC) maturation. While antigen presentation is hindered by the presence of the M6Po clusters, the incorporation of the M6Po clusters leads to increased activation of DCs, thus demonstrating their potential in improving vaccine adjuvanticity by intraendosomally active TLR ligands. Show less
Self-adjuvanting vaccines, wherein an antigenic peptide is covalently bound to an immunostimulating agent, have been shown to be promising tools for immunotherapy. Synthetic Toll-like receptor (TLR... Show moreSelf-adjuvanting vaccines, wherein an antigenic peptide is covalently bound to an immunostimulating agent, have been shown to be promising tools for immunotherapy. Synthetic Toll-like receptor (TLR) ligands are ideal adjuvants for covalent linking to peptides or proteins. We here introduce a conjugation-ready TLR4 ligand, CRX-527, a potent powerful lipid A analogue, in the generation of novel conjugate-vaccine modalities. Effective chemistry has been developed for the synthesis of the conjugation-ready ligand as well as the connection of it to the peptide antigen. Different linker systems and connection modes to a model peptide were explored, and in vitro evaluation of the conjugates showed them to be powerful immune-activating agents, significantly more effective than the separate components. Mounting the CRX-527 ligand at the N-terminus of the model peptide antigen delivered a vaccine modality that proved to be potent in activation of dendritic cells, in facilitating antigen presentation, and in initiating specific CD8(+) T-cell-mediated killing of antigen-loaded target cells in vivo. Synthetic TLR4 ligands thus show great promise in potentiating the conjugate vaccine platform for application in cancer vaccination. Show less
Kim, R.Q.; Misra, M.; Gonzalez, A.; Tomašković, I.; Shin, D.; Schindelin, H.; ... ; Heden- van Noort, G.J. van der 2020
Legionnaires’ disease is caused by infection with the intracellularly replicating Gram‐negative bacterium Legionella pneumophila. This pathogen uses an unconventional way of ubiquitinating host... Show moreLegionnaires’ disease is caused by infection with the intracellularly replicating Gram‐negative bacterium Legionella pneumophila. This pathogen uses an unconventional way of ubiquitinating host proteins by generating a phosphoribosyl linkage between substrate proteins and ubiquitin by making use of an ADPribosylated ubiquitin (UbADPr) intermediate. The family of SidE effector enzymes that catalyze this reaction is counteracted by Legionella hydrolases, which are called Dups. This unusual ubiquitination process is important for Legionella proliferation and understanding these processes on a molecular level might prove invaluable in finding new treatments. Herein, a modular approach is used for the synthesis of triazole‐linked UbADPr, and analogues thereof, and their affinity towards the hydrolase DupA is determined and hydrolysis rates are compared to natively linked UbADPr. The inhibitory effects of modified Ub on the canonical eukaryotic E1‐enzyme Uba1 are investigated and rationalized in the context of a high‐resolution crystal structure reported herein. Finally, it is shown that synthetic UbADPr analogues can be used to effectively pull‐down overexpressed DupA from cell lysate. Show less
Self-adjuvanting vaccines, wherein an antigenic peptide is covalently bound to an immunostimulating agent, have been shown to be promising tools for immunotherapy. Synthetic Toll-like receptor (TLR... Show moreSelf-adjuvanting vaccines, wherein an antigenic peptide is covalently bound to an immunostimulating agent, have been shown to be promising tools for immunotherapy. Synthetic Toll-like receptor (TLR) ligands are ideal adjuvants for covalent linking to peptides or proteins. We here introduce a conjugation-ready TLR4 ligand, CRX-527, a potent powerful lipid A analogue, in the generation of novel conjugate-vaccine modalities. Effective chemistry has been developed for the synthesis of the conjugation-ready ligand as well as the connection of it to the peptide antigen. Different linker systems and connection modes to a model peptide were explored, and in vitro evaluation of the conjugates showed them to be powerful immune-activating agents, significantly more effective than the separate components. Mounting the CRX-527 ligand at the N-terminus of the model peptide antigen delivered a vaccine modality that proved to be potent in activation of dendritic cells, in facilitating antigen presentation, and in initiating specific CD8+ T-cell-mediated killing of antigen-loaded target cells in vivo. Synthetic TLR4 ligands thus show great promise in potentiating the conjugate vaccine platform for application in cancer vaccination. Show less
Enotarpi, J.; Tontini, M.; Balocchi, C.; Es, D. van der; Auberger, L.C.; Balducci, E.; ... ; Adamo, R. 2020
Correction to: Nature Communicationshttps://doi.org/10.1038/s41467-020-18279-x, published online 7 September 2020.The original version of this Article contained errors in Fig. 1. The label ‘a’ was... Show moreCorrection to: Nature Communicationshttps://doi.org/10.1038/s41467-020-18279-x, published online 7 September 2020.The original version of this Article contained errors in Fig. 1. The label ‘a’ was omitted for the left panel and the label ‘b’ was omitted for the right panel. In Fig. 1b, the right parenthesis was incorrectly positioned indicating a 4-carbon linker, rather than the correct 6-carbon linker. These errors have been corrected in both the PDF and HTML versions of the Article. Show less
