Synthetic Glycolipids as Molecular Vaccine Adjuvants: Mechanism of Action in Human Cells and In Vivo Activity.

Modern adjuvants for vaccine formulations are immunostimulating agents whose action is based on the activation of pattern recognition receptors (PRRs) by well-defined ligands to boost innate and adaptive immune responses. Monophosphoryl lipid A (MPLA), a detoxified analogue of lipid A, is a clinically approved adjuvant that stimulates toll-like receptor 4 (TLR4). The synthesis of MPLA poses manufacturing and quality assessment challenges. Bridging this gap, we report here the development and preclinical testing of chemically simplified TLR4 agonists that could sustainably be produced in high purity and on a large scale. Underpinned by computational and biological experiments, we show that synthetic monosaccharide-based molecules (FP compounds) bind to the TLR4/MD-2 dimer with submicromolar affinities stabilizing the active receptor conformation. This results in the activation of MyD88- and TRIF-dependent TLR4 signaling and the NLRP3 inflammasome. FP compounds lack in vivo toxicity and exhibit adjuvant activity by stimulating antibody responses with a potency comparable to MPLA.

Ionic-Liquid-Based Safe Adjuvants.

Adjuvants play a critical role in the design and development of novel vaccines. Despite extensive research, only a handful of vaccine adjuvants have been approved for human use. Currently used adjuvants are mostly composed of components that are non-native to the human body, such as aluminum salt, bacterial lipids, or foreign genomic material. Here, a new ionic-liquid-based adjuvant is explored, synthesized using two metabolites of the body, choline and lactic acid (ChoLa). ChoLa distributes the antigen efficiently upon injection, maintains antigen integrity, enhances immune infiltration at the injection site, and leads to a potent immune response against the antigen. Thus, it can serve as a promising safe adjuvant platform that can help to protect against pandemics and future infectious threats.

Combination of PEG-decorated black phosphorus nanosheets and immunoadjuvant for photoimmunotherapy of melanoma.

Photoimmunotherapy, which combines local photothermal therapy (PTT) with immunological stimulation, is a promising modality for cancer treatment. Herein, we have reported a photothermal-immunotherapy of melanoma using pegylated black phosphorus nanosheets (BP-PEG NSs) and imiquimod (R837) as the photothermal conversion agent and the immunoadjuvant, respectively. The photothermal stability of BP NSs was remarkably enhanced after the modification of poly(ethylene glycol) (PEG) by electrostatic interactions. The in situ generation of tumor-associated antigens by PTT elicited a strong immune response in the presence of R837, achieving a photoimmunotherapy of B16 melanoma. This photoimmunotherapy stimulated a stronger immune response both in vitro and in vivo than monotherapy, inducing a much greater release of cytokines such as IL-6, IL-12, and TNF-α. In vivo antitumor studies in B16 tumor-bearing mice demonstrated that photoimmunotherapy showed the best tumor inhibition effects. Our study suggested that BP-PEG NS-based PTT primed with an immunoadjuvant can be used for synergistic photoimmunotherapy of melanomas.

A CpG-riched plasmid as vaccine adjuvant reduce antigen dose of an inactivated Vibrio anguillarum vaccine in turbot (Scophthalmus maximus L.).

Inactivated vaccines are often applied with adjuvants in commercial fish farming. Although some mineral or non-mineral oil adjuvants show efficient improvement with inactivated vaccines, but sometimes bring side effects such as tissue adhesion and granulomatous lesion at the injection site. CpG ODN is a novel type of soluble adjuvant which has been proved to possess excellent advantages in fish vaccine development. In this study, we designed a tandem sequence of CpG ODN synthesized in plasmid pcDNA 3.1, and an inactivated Vibrio anguillarum vaccine developed in our previous work was chosen for determining the efficiency of the CpG-riched plasmids (pCpG) as an adjuvant. Results showed that pCpG we designed can offer higher immunoprotection with the vaccine. Interestingly, even below the minimum immune dosage of the vaccine, a high RPS of 84% was observed once the vaccine was administrated with the pCpG. Serum specific antibody titer, superoxide dismutase and total protein were enhanced and some immune genes related to both innate and adaptive immune response were upregulated, implying an effective auxiliary function of the pCpG. Totally, our study suggested that the pCpG is a potential and available adjuvant for turbot vaccine development.

Synthesis and biological activities of amino acids functionalized α-GalCer analogues.

Invariant natural killer T-cells (iNKT-cells) are promising targets for manipulating the immune system, which can rapidly release a large amount of Th1 and Th2 cytokines upon the engagement of their T cell receptor with glycolipid antigens presented by CD1d. In this paper, we wish to report a novel series of α-GalCer analogues which were synthesized by incorporation of l-amino acid methyl esters in the C-6' position of glycolipid. The evaluation of these synthetic analogues for their capacities to stimulate iNKT-cells into producing Th1 and Th2 cytokines both in vitro and in vivo indicated that they were potent CD1d ligands and could stimulate murine spleen cells into a higher release of the Th1 cytokine IFN-γ in vitro. In vivo, Gly-α-GalCer (1) and Lys-α-GalCer (3) showed more Th1-biased responses than α-GalCer, especially analogue 3 showed the highest selectivity for IFN-γ production (IFN-γ/IL-4 = 5.32) compared with α-GalCer (IFN-γ/IL-4 = 2.5) in vivo. These novel α-GalCer analogues might be used as efficient X-ray crystallographic probes to reveal the relationship between glycolipids and CD1d proteins in α-GalCer/CD1d complexes and pave the way for developing new potent immunostimulating agents.

Synthesis and Evaluation of Novel TLR2 Agonists as Potential Adjuvants for Cancer Vaccines.

Cancer immunotherapy has gained increasing attention due to its potential specificity and lack of adverse side effects when compared to more traditional modes of treatment. Toll-like receptor 2 (TLR2) agonists are lipopeptides possessing the S-[2,3-bis(palmitoyloxy)propyl]-l-cysteine (Pam2Cys) motif and exhibit potent immunostimulatory effects. These agonists offer a means of providing "danger signals" in order to activate the immune system toward tumor antigens. Thus, the development of TLR2 agonists is attractive in the search of potential immunostimulants for cancer. Existing SAR studies of Pam2Cys with TLR2 indicate that the structural requirements for activity are, for the most part, very intolerable. We have investigated the importance of stereochemistry, the effect of N-terminal acylation, and homologation between the two ester functionalities in Pam2Cys-conjugated lipopeptides on TLR2 activity. The R diastereomer is significantly more potent than the S diastereomer and N-terminal modification generally lowers TLR2 activity. Most notably, homologation gives rise to analogues which are comparatively active to the native Pam2Cys containing constructs.

Synthesis of a Self-Adjuvanting MUC1 Vaccine via Diselenide-Selenoester Ligation-Deselenization.

Access to lipopeptide-based vaccines for immunological studies remains a significant challenge owing to the amphipathic nature of the molecules, which makes them difficult to synthesize and purify to homogeneity. Here, we describe the application of a new peptide ligation technology, the diselenide-selenoester ligation (DSL), to access self-adjuvanting glycolipopeptide vaccines. We show that rapid ligation of glyco- and lipopeptides is possible via DSL in mixed organic solvent-aqueous buffer and, when coupled with deselenization chemistry, affords rapid and efficient access to a vaccine candidate possessing a MUC1 glycopeptide epitope and the lipopeptide adjuvant Pam2Cys. This construct was shown to elicit MUC1-specific antibody and cytotoxic T lymphocyte responses in the absence of any other injected lipids or adjuvants. The inclusion of the helper T cell epitope PADRE both boosted the antibody response and resulted in elevated cytokine production.

PeptoSomes for Vaccination: Combining Antigen and Adjuvant in Polypept(o)ide-Based Polymersomes.

In this work, the first vaccine is reported based on a PeptoSome, which contains a model antigen (SIINFEKL) and adjuvant (CpG). PeptoSomes are polypept(o)ide-based polymersomes built of a block-copolymer with polysarcosine (PSar) as the hydrophilic block (X n = 111) and poly(benzyl-glutamic acid) (PGlu(OBn)) as the hydrophobic one (X n = 46). The polypept(o)ide is obtained with low dispersity index of 1.32 by controlled ring-opening polymerization. Vesicle formation by dual centrifugation technique allows for loading of vesicles up to 40 mol%. PeptoSomes are characterized by multiangle dynamic light scattering, static light scattering, and cryogenic transmission electron microscopy (cryoTEM). The PeptoSomes have a hydrodynamic radius of 39.2 nm with a low dispersity (µ 2 = 0.1). The ρ-ratio R g /R h of 0.95 already indicates that vesicles are formed, which can be confirmed by cryoTEM. Loaded PeptoSomes deliver the antigen (SIINFEKL) and an adjuvant (CpG) simultaneously into dendritic cells (DCs). Upon cellular uptake, dendritic cells are stimulated and activated, which leads to expression of cluster of differentiation CD80, CD86, and MHCII, but induces excretion of proinflammatory cytokines (e.g., TNFα). Furthermore, DC-mediated antigen-specific T-cell proliferation is achieved, thus underlining the enormous potential of PeptoSomes as a versatile platform for vaccination.

Carbohydrate fatty acid monosulphate esters are safe and effective adjuvants for humoral responses.

Carbohydrate fatty acid sulphate esters (CFASEs) formulated in a squalane-in-water emulsion are effective adjuvants for humoral responses to a wide range of antigens in various animal species but rise in body temperature and local reactions albeit mild or minimal hampers application in humans. In rabbits, body temperature increased 1°C one day after intramuscular (IM) injection, which returned to normal during the next day. The effect increased with increasing dose of CFASE but not with the number of injections (up to 5). Antigen enhanced the rise in body temperature after booster immunization (P<0.01) but not after priming. Synthetic CFASEs are mixtures of derivatives containing no sulphate, one or multiple sulphate groups and the monosulphate derivatives (CMS) were isolated, incorporated in a squalane in-water emulsion and investigated. In contrast to CFASE, CMS adjuvant did not generate rise in body temperature or local reactions in rabbits immunized with a purified, recombinant malaria chimeric antigen R0.10C. In comparison to alum, CMS adjuvant revealed approximately 30-fold higher antibody titres after the first and >100-fold after the second immunization. In ferrets immunized with 7.5µg of inactivated influenza virus A/H7N9, CMS adjuvant gave 100-fold increase in HAI antibody titres after the first and 25-fold after the second immunisation, which were 10-20-fold higher than with the MF59-like AddaVax adjuvant. In both models, a single immunisation with CMS adjuvant revealed similar or higher titres than two immunisations with either benchmark, without detectable systemic and local adverse effects. Despite striking chemical similarities with monophospholipid A (MPL), CMS adjuvant did not activate human TLR4 expressed on HEK cells. We concluded that the synthetic CMS adjuvant is a promising candidate for poor immunogens and single-shot vaccines and that rise in body temperature, local reactions or activation of TLR4 is not a pre-requisite for high adjuvanticity.

Plantas com potencial adaptogénico utilizadas na medicina popular brasileira: Ptychapetalum olacaides, Pfaffia spp. E Trichilia catigua / Plantas con potencial adaptogénico utilizadas en la medicina popular brasileña: Ptychopetalum olacoides, Pfaflia spp. y Trichilia catigua / Potentially adaptogenic plants used in Brazilian folk medicine: Ptychopetalum olacoides, Pfaffia spp. A Trichilia catigua

O estresse já foi definido como uma reaçáo capaz de perturbar a homeostase do organismo. Nesse contexto es adaptógenos permitem equilibrar o organismo durante tais situaçoes. Pesquisas demonstram que a flora brasileira e rica em especies com potencial adaptógeno, dentre as quais destacam: Ptycopetalum olacoides (marapuama), descrita por seus efeitos anti-inflamatórios, antioxidante, antibacteriano e estimulante de sistema imunológico; o genero Pfaffia spp, entre eles o ginseng brasileiro, com usos na fadiga cronica, estresse, impotencia masculina e reduçáo nos niveis circulantes de colesterol; e a Trichilia catigua (catuaba) utilizada como tonico para tratamento do estresse, fadiga, impotencia e déficit de memoria (AU)

El estrés se define como una reacción capaz de alterar la homeostasis del organismo. En este contexto, los adaptógenes permiten equilibrar el organismo en tales situaciones. Las investigaciones han mostrado que la fiera brasileña es rica en especies con potencial adaptegénice, entre las que destacan: Ptycopetalum olacoides (marapuama), descrita por sus efectos estimulantes, antiinflamatories, antioxidantes, antibacterianes e inmuneestimulantes; Pfaffia spp, (ginseng brasileño), con usos en fatiga crónica, estrés, impotencia masculina y reducción de los niveles plasmáticos de colesterol; y Trichilia catigua (catuaba), utilizada en el tratamiento del estrés, la fatiga, la impotencia y el déficit de memoria (AU)

Stress has already been defined as a reaction able to disrupt the homeostasis of the organism. In this context adaptogens allow te balance the body in such situations. Research has shown that Brazilian flora is rich in species with adaptegenic potential, among which the following are outstanding: Ptycopetalum olacoides (marapuama), known for its anti-inflammatory, antiexidant, antibacterial and immunestimulant effects; the genus Pfaffia spp, including the Brasilian ginseng, used in chronic fatigue, stress, male impotence and reduction of blood cholesterol levels; and Trichilia catigua (catuaba) used for the treatment of stress, fatigue, impotence and memory deficit (AU)

Synthesis and immunostimulatory activity of substituted TLR7 agonists.

Fifteen new substituted adenines were synthesized as potential TLR7 agonists. These compounds, along with 9 previously reported compounds, were analyzed for TLR7 activity and for the selective stimulation of B cell proliferation. Several functionalized derivatives exhibit significant activity, suggesting their potential for use as vaccine adjuvants.

Green synthesis and evaluation of silver nanoparticles as adjuvant in rabies veterinary vaccine.

BACKGROUND: Green synthesis of nanoparticles by plant extracts plays a significant role in different applications. Recently, several studies were conducted on the use of nanoparticles as adjuvant. The main aim of this study was to evaluate green synthesized silver nanoparticles (AgNPs) as adjuvant in rabies veterinary vaccine and compare the results with the existing commercially available alum adjuvant. MATERIALS AND METHODS: In the current study, AgNPs were prepared by the reduction of aqueous silver nitrate by leaf extract of Eucalyptus procera. The formation of AgNPs was confirmed by ultraviolet (UV)-visible spectrophotometer, scanning electron microscopy, dynamic light scattering, and X-ray diffraction analysis. Then, different amounts of AgNPs (200 µg, 400 µg, 600 µg, and 800 µg) were added to 1 mL of inactivated rabies virus. The loaded vaccines (0.5 mL) were injected intraperitoneally into six Naval Medical Research Institute mice in each group on days 1 and 7. On the 15th day, the mice were intracerebrally challenged with 0.03 mL of challenge rabies virus (challenge virus strain-11, 20 lethal dose [20 LD50]), and after the latency period of rabies disease in mice (5 days), the mice were monitored for 21 days. Neutralizing antibodies against rabies virus were also investigated using the rapid fluorescent focus inhibition test method. The National Institutes of Health test was performed to determine the potency of optimum concentration of AgNPs as adjuvant. In vitro toxicity of AgNPs was assessed in L929 cell line using MTT assay. In addition, in vivo toxicity of AgNPs and AgNPs-loaded vaccine was investigated according to the European Pharmacopeia 8.0. RESULTS: AgNPs were successfully synthesized, and the identity was confirmed by UV-visible spectrophotometry and X-ray diffraction analysis. The prepared AgNPs were spherical in shape, with an average size of 60 nm and a negative zeta potential of -14 mV as determined by dynamic light scattering technique. The highest percentage of viability was observed at 15 mg/kg and 20 mg/kg of AgNPs-loaded vaccine concentrations after injecting into the mice. The calculated potencies for alum-containing vaccine and AgNPs-loaded vaccine (dose 15 mg/kg) were 1.897 and 1.303, respectively. MTT assay demonstrated that alum at the concentration of 10 mg/mL was toxic, but AgNPs were not toxic. The in vivo toxicity also elucidated the safety of AgNPs and AgNPs-loaded vaccine in mice and dogs, respectively. CONCLUSION: In the current study, for the first time, the adjuvanticity effect of green synthesized AgNPs on veterinary rabies vaccine potency with no in vivo toxicity was elucidated according to the European Pharmacopeia 8.0.

Development of Improved Vaccine Adjuvants Based on the Saponin Natural Product QS-21 through Chemical Synthesis.

Vaccines based on molecular subunit antigens are increasingly being investigated due to their improved safety and more precise targeting compared to classical whole-pathogen vaccines. However, subunit vaccines are inherently less immunogenic; thus, coadministration of an adjuvant to increase the immunogenicity of the antigen is often necessary to elicit a potent immune response. QS-21, an immunostimulatory saponin natural product, has been used as an adjuvant in conjunction with various vaccines in numerous clinical trials, but suffers from several inherent liabilities, including scarcity, chemical instability, and dose-limiting toxicity. Moreover, little is known about its mechanism of action. Over a decade-long effort, beginning at the University of Illinois at Urbana-Champaign and continuing at the Memorial Sloan Kettering Cancer Center (MSKCC), the group of Prof. David Y. Gin accomplished the total synthesis of QS-21 and developed a practical semisynthetic approach to novel variants that overcome the liabilities of the natural product. First, semisynthetic QS-21 variants were designed with stable amide linkages in the acyl chain domain that exhibited comparable in vivo adjuvant activity and lower toxicity than the natural product. Further modifications in the acyl chain domain and truncation of the linear tetrasaccharide domain led to identification of a trisaccharide variant with a simple carboxylic acid side chain that retained potent adjuvant activity, albeit with reemergence of toxicity. Conversely, an acyl chain analogue terminating in a free amine was inactive but enabled chemoselective functionalization with radiolabeled and fluorescent tags, yielding adjuvant-active saponin probes that, unlike inactive congeners, accumulated in the lymph nodes in vaccinated mice and internalized into dendritic cells. Subtle variations in length, stereochemistry, and conformational flexibility around the central glycosidic linkage provided QS-21 variants with adjuvant activities that correlated with specific conformations found in molecular dynamics simulations. Notably, deletion of the entire branched trisaccharide domain afforded potent, truncated saponin variants with negligible toxicity and improved synthetic access, facilitating subsequent investigation of the triterpene core. The triterpene C4-aldehyde substituent, previously proposed to be important for QS-21 adjuvant activity, proved to be dispensable in these truncated saponin variants, while the presence of the C16 hydroxyl group enhanced activity. Novel adjuvant conjugates incorporating the small-molecule immunopotentiator tucaresol at the acyl chain terminus afforded adjuvant-active variants but without significant synergistic enhancement of activity. Finally, a new divergent synthetic approach was developed to provide versatile and streamlined access to additional linear oligosaccharide domain variants with modified sugars and regiochemistries, opening the door to the rapid generation of diverse, synthetically accessible analogues. In this Account, we summarize these multidisciplinary studies at the interface of chemistry, immunology, and medicine, which have provided critical information on the structure-activity relationships (SAR) of this Quillaja saponin class; access to novel, potent, nontoxic adjuvants for use in subunit vaccines; and a powerful platform for investigations into the mechanisms of saponin immunopotentiation.

Acetylated Trivalent Mannobioses: Chemical Modification, Structural Elucidation, and Biological Evaluation.

People suffering from allergies can be treated with repeated injections of increasing amounts of a specific allergen. This type of specific immunotherapy is currently the only way to treat the underlying pathological immune response associated with an allergy. The approach can afford long-lasting protection, but the process takes 3-5 years, can produce allergic reactions, and in severe cases treatment is often aborted due to anaphylaxis. However, treatment can be optimized with the use of specific adjuvants that modify the immune response, its duration, and that increase the production of the correct type of antibodies. In the pursuit of such adjuvants, two new trivalent acetylated ß-(1→2)-linked mannobioses based on a previously discovered lead molecule were prepared. The new molecules, along with the previously developed lead, were investigated by rigorous NMR and molecular modeling experiments in order to elucidate their behavior and preferred conformations in solution. Furthermore, the molecules were subjected to a biological investigation in which their immunostimulatory properties were evaluated by assessing their effect on the production of TH 2-type cytokine interleukin-4 (IL-4) and Treg pro-inflammatory cytokine tumor necrosis factor (TNF). Treatment of peripheral mononuclear blood cell cultures from patients suffering from birch allergy with birch allergen Bet v induced a strong IL-4 response, whereas the same treatment together with the trivalent acetylated mannobioses caused significant suppression of the induced IL-4.

Lewis Acid Induced Anomerization of Se-Glycosides. Application to Synthesis of α-Se-GalCer.

The TiCl4 induced anomerization of selenium glycosides of galacturonic acid derivatives is reported. The reaction was successful for galacturonic acid when various alkyl, alkenyl, alkynyl, saccharide, steroid, and lipid groups were attached to the anomeric Se atom. An increased amount of TiCl4 and/or higher temperature were needed to ensure completion of the reaction in some cases. Yields were higher for reactions carried out at higher dilution. The reaction was applied to the synthesis of Se-based mimics of the potent immunostimulant α-GalCer (KRN7000).

Design and evaluation of surface and adjuvant modified PLGA microspheres for uptake by dendritic cells to improve vaccine responses.

Designing strategies for targeting antigens to dendritic cells is a major goal in vaccinology. Here, PLGA (poly lactic-co-glycolic acid) microspheres and with several surface modifications that affect to their uptake by human blood primary dendritic cells and monocytes have been evaluated. Higher uptake was found by all the cell types when cationic microspheres (PLGA modified with polyethylene imine) were used. These cationic particles were in vivo evaluated in mice. In addition, MPLA(1) or poly(I:C)(2) and α-GalCer(3) were also encapsulated to address their adjuvant effect. All the microspheres were able to produce humoral immune responses, albeit they were higher for cationic microspheres. Moreover, surface charge seemed to have a role on biasing the immune response; cationic microspheres induced higher IFN-γ levels, indicative of Th1 activation, while unmodified ones mainly triggered IL4 and IL17A release, showing Th2 activation. Thus, we have shown here the potential and versatility of these MS, which may be tailored to needs.

Quaternary Indolizidine and Indolizidone Iminosugars as Potential Immunostimulating and Glycosidase Inhibitory Agents: Synthesis, Conformational Analysis, Biological Activity, and Molecular Docking Study.

New quaternary indolizidine iminosugars, with hydroxymethyl group at the ring junction, namely, C-8a-hydroxymethyl-1-deoxycastanospermine congeners 1a, 2a, 3a and their 3-oxo analogs 1b, 2b, and 3b were synthesized by using intramolecular reductive aminocyclization/lactamization of d-mannose/D-glucose derived C5-γ-azido esters as a key step wherein both the rings of the indolizidine skeleton were built up in one pot following the cascade reaction pathway. The conformations ((5)C8 or (8)C5) of 1-3 were assigned on the basis of the (1)H NMR studies. All compounds were found to be potent inhibitors of various glycosidase enzymes with Ki and IC50 values in the micromolar/nanomolar concentration range and further substantiated by molecular docking studies. The effect of synthesized iminosugars 1-3 on the cytokine secretion of IL-4, IL-6, and IFN-γ was evaluated. All compounds were found to be TH1 bias increasing the TH1/TH2 cytokines ratio (IL-6 and IL-4) indicating their potency as immunostimulating agents. Our study suggests that immunomodulatory activity of indolizidine iminosugars can be tuned by minor structural/stereochemical alterations.

Near-infrared dye-conjugated amphiphilic hyaluronic acid derivatives as a dual contrast agent for in vivo optical and photoacoustic tumor imaging.

Amphiphilic hyaluronic acid (HA) derivatives bearing hydrophobic indocyanine green dye derivatives and hydrophilic poly(ethylene glycol) were synthesized through the use of condensation and copper-catalyzed click cyclization reactions. The amphiphilic HA derivatives dissolved in water and formed self-assemblies in which the near-infrared dyes were tightly packed and arranged to form dimers or H-aggregates. By irradiating an aqueous solution of HA derivatives with near-infrared light, photoacoustic signals were detected along with fluorescence emission. Self-assemblies consisting of HA derivatives could smoothly accumulate in tumor tissues by passive tumor targeting. By utilizing HA derivatives as a contrast agent, tumor sites were clearly visualized by optical imaging as well as by photoacoustic tomography.

Synthesis and immunoregulatory activities of conjugates of a Toll-like receptor 7 inert ligand.

In the synthesis and modification of the analogs of an adenine type of Toll-like receptor (TLR) 7 agonists, we found a special compound, 9-propionyloxy-8-hydroxy-2-(2-methoxyethoxy)-adenine (6). It is a synthesized TLR7 inert ligand, which does not respond to TLR7 itself. However, it can be coupled with protein or peptide antigens via propionyloxy functional group to promote their immunogenicity significantly. The compound was covalently coupled to protein and peptide to get the conjugates. The inductivity of cytokine production by the conjugates was 872.4-fold compared with the unconjugated antigens in vitro by mouse splenocyte. These data show that the immunostimulatory activity of inert TLR7 ligand can be endowed, and the activity of antigens can be amplified by conjugation with various proteins and peptides, thus broadening the potential therapeutic application and reducing the risk of TLR7 agonists' side effects.

Oligo-ß-(1 → 3)-glucans: impact of thio-bridges on immunostimulating activities and the development of cancer stem cells.

Recent developments of innovative anticancer therapies are based on compounds likely to stimulate the immune defense of the patients. ß-(1 → 3)-Glucans are natural polysaccharides well-known for their immunostimulating properties. We report here on the synthesis of small oligo-ß-(1 → 3)-glucans characterized by thioglycosidic linkages. The presence of sulfur atom(s) was not only crucial to prolong in vivo immunoactive activities in time, compared to native polysaccharides, but sulfur atoms also had a direct impact on the development of colorectal cancer stem cells. As a result, a short, pure, and structurally well-defined trisaccharidic thioglucan demonstrated similar activities compared to those of natural laminarin.