Robust stimulation of humoral and cellular immune responses following vaccination with antigen-loaded beta-glucan particles

β-Glucan-A promising immunocyte-targeting drug delivery vehicle: Superiority, applications and future prospects

Drug delivery technologies that could convert promising therapeutics into successful therapies have been under broad research for many years. Recently, β-glucans, natural-occurring polysaccharides extracted from many organism species such as yeast, fungi and bacteria, have attracted increasing attention to serve as drug delivery carriers. With their unique structure and innate immunocompetence, β-glucans are considered as promising carriers for targeting delivery especially when applied in the vaccine construction and oral administration of therapeutic agents. In this review, we focus on three types of β-glucans applied in the drug delivery system including yeast β-glucan, Schizophyllan and curdlan, highlighting the benefits of β-glucan based delivery system. We summarize how β-glucans as delivery vehicles have aided various therapeutics ranging from macromolecules including proteins, peptides and nucleic acids to small molecular drugs to reach desired cells or organs in terms of loading strategies. We also outline the challenges and future directions for developing the next generation of β-glucan based delivery systems.

Yeast glucan particles: An express train for oral targeted drug delivery systems

As an emerging drug delivery vehicle, yeast glucan particles (YGPs) derived from yeast cells could be specifically taken up by macrophages. Therefore, these vehicles could rely on the recruitment of macrophages at the site of inflammation and tumors to enable targeted imaging and drug delivery. This review summarizes recent advances in the application of YGPs in oral targeted delivery systems, covering the basic structure of yeast cells, methods for pre-preparation, drug encapsulation and characterization. The mechanism and validation of the target recognition interaction of YGPs with macrophages are highlighted, and some inspiring cases are presented to show that yeast cells have promising applications. The future chances and difficulties that YGPs will confront are also emphasized throughout this essay. YGPs are not only the "armor" but also the "compass" of drugs in the process of targeted drug transport. This system is expected to provide a new idea about the oral targeted delivery of anti-inflammatory and anti-tumor drugs, and furthermore offer an effective delivery strategy for targeted therapy of other macrophage-related diseases.

RNA Vaccines: Yeast as a Novel Antigen Vehicle

In the last decades, technological advances for RNA manipulation enabled and expanded its application in vaccine development. This approach comprises synthetic single-stranded mRNA molecules that direct the translation of the antigen responsible for activating the desired immune response. The success of RNA vaccines depends on the delivery vehicle. Among the systems, yeasts emerge as a new approach, already employed to deliver protein antigens, with efficacy demonstrated through preclinical and clinical trials. β-glucans and mannans in their walls are responsible for the adjuvant property of this system. Yeast β-glucan capsules, microparticles, and nanoparticles can modulate immune responses and have a high capacity to carry nucleic acids, with bioavailability upon oral immunization and targeting to receptors present in antigen-presenting cells (APCs). In addition, yeasts are suitable vehicles for the protection and specific delivery of therapeutic vaccines based on RNAi. Compared to protein antigens, the use of yeast for DNA or RNA vaccine delivery is less established and has fewer studies, most of them in the preclinical phase. Here, we present an overview of the attributes of yeast or its derivatives for the delivery of RNA-based vaccines, discussing the current challenges and prospects of this promising strategy.

Engineered Living Materials for Advanced Diseases Therapy

Natural living materials serving as biotherapeutics exhibit great potential for treating various diseases owing to their immunoactivity, tissue targeting, and other biological activities. In this review, the recent developments in engineered living materials, including mammalian cells, bacteria, viruses, fungi, microalgae, plants, and their active derivatives that are used for treating various diseases are summarized. Further, the future perspectives and challenges of such engineered living material-based biotherapeutics are discussed to provide considerations for future advances in biomedical applications.

One Step Purification-Vaccine Delivery System

Glucan particles (GPs) are hollow, porous 3-5 µm microspheres derived from the cell walls of Baker's yeast (Saccharomyces cerevisiae). Their 1,3-β-glucan outer shell allows for receptor-mediated uptake by macrophages and other phagocytic innate immune cells expressing β-glucan receptors. GPs have been used for the targeted delivery of a wide range of payloads, including vaccines and nanoparticles, encapsulated inside the hollow cavity of GPs. In this paper, we describe the methods to prepare GP-encapsulated nickel nanoparticles (GP-Ni) for the binding of histidine (His)-tagged proteins. His-tagged Cda2 cryptococcal antigens were used as payloads to demonstrate the efficacy of this new GP vaccine encapsulation approach. The GP-Ni-Cda2 vaccine was shown to be comparable to our previous approach utilizing mouse serum albumin (MSA) and yeast RNA trapping of Cda2 in GPs in a mouse infection model. This novel GP-Ni approach allows for the one-step binding of His-tagged vaccine antigens and encapsulation in an effective delivery vehicle to target vaccines to antigen-presenting cells (APCs), antigen discovery, and vaccine development.

Immunological correlates of protection following vaccination with glucan particles containing Cryptococcus neoformans chitin deacetylases

Vaccination with glucan particles (GP) containing the Cryptococcus neoformans chitin deacetylases Cda1 and Cda2 protect mice against experimental cryptococcosis. Here, immunological correlates of vaccine-mediated protection were explored. Studies comparing knockout and wild-type mice demonstrated CD4⁺ T cells are crucial, while B cells and CD8⁺ T cells are dispensable. Protection was abolished following CD4⁺ T cell depletion during either vaccination or infection but was retained if CD4⁺ T cells were only partially depleted. Vaccination elicited systemic and durable antigen-specific immune responses in peripheral blood mononuclear cells (PBMCs), spleens, and lungs. Following vaccination and fungal challenge, robust T-helper (Th) 1 and Th17 responses were observed in the lungs. Protection was abrogated in mice congenitally deficient in interferon (IFN) γ, IFNγ receptor, interleukin (IL)-1β, IL-6, or IL-23. Thus, CD4⁺ T cells and specific proinflammatory cytokines are required for GP-vaccine-mediated protection. Importantly, retention of protection in the setting of partial CD4⁺ T depletion suggests a pathway for vaccinating at-risk immunocompromised individuals.

Feasibility of Brewer's Spent Yeast Microcapsules as Targeted Oral Carriers

Brewer's spent yeast (BSY) microcapsules have a complex network of cell-wall polysaccharides that are induced by brewing when compared to the baker's yeast (Saccharomyces cerevisiae) microcapsules. These are rich in (β1→3)-glucans and covalently linked to (α1→4)- and (β1→4)-glucans in addition to residual mannoproteins. S. cerevisiae is often used as a drug delivery system due to its immunostimulatory potential conferred by the presence of (β1→3)-glucans. Similarly, BSY microcapsules could also be used in the encapsulation of compounds or drug delivery systems with the advantage of resisting digestion conferred by (β1→4)-glucans and promoting a broader immunomodulatory response. This work aims to study the feasibility of BSY microcapsules that are the result of alkali and subcritical water extraction processes, as oral carriers for food and biomedical applications by (1) evaluating the resistance of BSY microcapsules to in vitro digestion (IVD), (2) their recognition by the human Dectin-1 immune receptor after IVD, and (3) the recognition of IVD-solubilized material by different mammalian immune receptors. IVD digested 44-63% of the material, depending on the extraction process. The non-digested material, despite some visible agglutination and deformation of the microcapsules, preserved their spherical shape and was enriched in (β1→3)-glucans. These microcapsules were all recognized by the human Dectin-1 immune receptor. The digested material was differentially recognized by a variety of lectins of the immune system related to (β1→3)-glucans, glycogen, and mannans. These results show the potential of BSY microcapsules to be used as oral carriers for food and biomedical applications.

Microbial exopolysaccharides-β-glucans-as promising postbiotic candidates in vaccine adjuvants

The urgent task of creating new, enhanced adjuvants is closely related to our comprehension of their mechanisms of action. A few adjuvants have shown sufficient efficacy and low toxicity to be allowed for use in human vaccines, despite the fact that they have a long history and an important function. Adjuvants have long been used without a clear understanding of how precisely they augment the immune response. The rational production of stronger and safer adjuvants has been impeded by this lack of information, which necessitates more mechanistic research to support the development of vaccines. Carbohydrate structures-polygalactans, fructans, β-D-glucans, α-D-glucans, D-galactose, and D-glucose-are desirable candidates for the creation of vaccine adjuvants and immunomodulators because they serve important functions in nature and are often biocompatible, safe, and well tolerated. In this review, we have discussed recent advances in microbial-derived carbohydrate-based adjuvants, their immunostimulatory activity, and the implications of this for vaccine development, along with the critical view on the microbial sources, chemical composition, and biosynthetic pathways.

A Potent Micron Neoantigen Tumor Vaccine GP-Neoantigen Induces Robust Antitumor Activity in Multiple Tumor Models

Therapeutic tumor neoantigen vaccines have been widely studied given their good safety profile and ability to avoid central thymic tolerance. However, targeting antigen-presenting cells (APCs) and inducing robust neoantigen-specific cellular immunity remain challenges. Here, a safe and broad-spectrum neoantigen vaccine delivery system is proposed (GP-Neoantigen) based on β-1,3-glucan particles (GPs) derived from Saccharomyces cerevisiae and coupling peptide antigens with GPs through convenient click chemistry. The prepared system has a highly uniform particle size and high APC targeting specificity. In mice, the vaccine system induced a robust specific CD8⁺ T cell immune response and humoral immune response against various conjugated peptide antigens and showed strong tumor growth inhibitory activity in EG7·OVA lymphoma, B16F10 melanoma, 4T1 breast cancer, and CT26 colon cancer models. The combination of the toll-like receptors (TLRs) agonist PolyI:C and CpG 2395 further enhanced the antitumor response of the particle system, achieving complete tumor clearance in multiple mouse models and inducing long-term rejection of reinoculated tumors. These results provide the broad possibility for its further clinical promotion and personalized vaccine treatment.

Bile acid linked β-glucan nanoparticles for liver specific oral delivery of biologics

Oral delivery remains one of the most convenient routes for drug administration compared to intravenous, intramuscular, and via suppositories. However, due to the risk of degradation, and proteolysis of molecules in the acidic gastric medium, as well as the difficulty of transporting large molecules through the intestinal membrane, more than half of the therapeutic molecules are prohibited for oral administration. Moreover, most of the large molecules and biological therapeutics are not available in oral dosage form due to their instability in the stomach and inability of intestinal absorption. To achieve expected bioavailability, an orally administered therapeutic molecule must be protected within the stomach, and transportation facilitated via the small intestine. In this project, we have introduced a hybrid carrier, composed of Taurocholic Acid (TA) and β-Glucan (TAG), that is shown to be effective for the simultaneous protection of the biologics in acidic buffer and simulated gastric juice as well as facilitate enhanced absorption and transportation via the small intestine. In this project, we have used an eGFP encoded plasmid as a model biologic to prepare particles mediated with TAG. TAG show the potential of enhancing transfection and expression of eGFP as we have observed two fold higher expression in the cell upon coincubation for 4 h. In vivo studies on orally dosed mice showed that eGFP expression in the liver was significantly higher in TAG containing particles compared to particles without TAG. The findings suggest that the TAG carrier is capable of not only preserving biologics but also transporting them more efficiently to the liver. As a result, this strategy can be employed for a variety of liver-targeted therapeutic delivery to treat a variety of liver diseases.

Yeast as carrier for drug delivery and vaccine construction

Yeast has been employed as an effective derived drug carrier as a unicellular microorganism. Many research works have been devoted to the encapsulation of nucleic acid compounds, insoluble small molecule drugs, small molecules, liposomes, polymers, and various nanoparticles in yeast for the treatment of disease. Recombinant yeast-based vaccine carriers (WYV) have played a major role in the development of vaccines. Herein, the latest reports on the application of yeast carriers and the development of related research are summarized, a conceptual description of gastrointestinal absorption of yeast carriers, as well as the various package forms of different drug molecules and nanoparticles in yeast carriers are introduced. In addition, the advantages and development of recombinant yeast vaccine carriers for the disease, veterinary and aquaculture applications are discussed. Moreover, the current challenges and future directions of yeast carriers are proposed.

Brewer's yeast polysaccharides - A review of their exquisite structural features and biomedical applications

Recent advances on brewer's yeast cell wall polysaccharides have unraveled exquisite structural features and diverse composition with (β1→3), (β1→6), (α1→4), (β1→4)-mix-linked glucans that are recognized to interact with different cell receptors and trigger specific biological responses. Herein, a comprehensive showcase of structure-biofunctional relationships between yeast polysaccharides and their biological targets is highlighted, with a focus on polysaccharide features that govern the biomedical activity. The insolubility of β-glucans is a crucial factor for binding and activation of Dectin-1 receptor, operating as adjuvants of immune responses. Contrarily, soluble low molecular weight β-glucans have a strong inhibition of reactive oxygen species production, acting as antagonists of Dectin-1 mediated signaling. Soluble glucan-protein moieties can also act as antitumoral agents. The balance between mannoproteins-TLR2 and β-glucans-Dectin-1 receptors-activation is crucial for osteogenesis. Biomedical applications value can also be obtained from yeast microcapsules as oral delivery systems, where highly branched (β1→6)-glucans lead to higher receptor affinity.

Immunoproteomic and Immunopeptidomic Analyses of Histoplasma capsulatum Reveal Promiscuous and Conserved Epitopes Among Fungi With Vaccine Potential

As there are more than 6 million human deaths due to mycoses each year, there is an urgent need to develop fungal vaccines. Moreover, given the similarities among pathogenic fungi, it may be possible to create a multi-fungi vaccine. In this study, we combined immunoproteomic and immunopeptidomic methods, for which we have adapted a technique based on co-immunoprecipitation (Co-IP) that made it possible to map Histoplasma capsulatum epitopes for the first time in a natural context using murine dendritic cells (DCs) and macrophages (Mφ). Although polysaccharide epitopes exist, this research focused on mapping protein epitopes as these are more immunogenic. We used different algorithms to screen proteins and peptides identified by two-dimensional electrophoresis (2-D) and Co-IP. Seventeen proteins were revealed by 2-D gels, and 45 and 24 peptides from distinct proteins were presented by DCs and Mφ, respectively. We then determined which epitopes were restricted to MHC-I and II from humans and mice and showed high promiscuity, but lacked identity with human proteins. The 4 most promising peptides were synthesized, and the peptides with and without incorporation into glucan particles induced CD4+ and CD8+ T cell proliferation and produced a Th1 and Th17 response marked by the secretion of high levels of IFN-γ, IL-17 and IL-2. These epitopes were from heat shock protein 60, enolase, and the ATP-dependent molecular chaperone HSC82, and they each have a high degree of identity with proteins expressed by other medically important pathogenic fungi. Thus, the epitopes described in this study have the potential for use in the development of vaccines that could result in cross-protection among fungal species.

Polyethyleneimine-complexed charge-reversed yeast cell walls for the enhanced oral delivery of pseudovirus-based antigens

Oral vaccination has wide applicability in poor areas, particularly during the epidemic periods of infectious diseases. However, successful oral antigen delivery and immune activation remain highly challenging due to the instability of vaccines in gastric acid and the low capture of antigens in the intestine. Here, we present a facile approach for the preparation of a robust oral delivery system via encapsulating antigen-carrying pseudoviruses inside positively charged polyethyleneimine-modified yeast capsules (P-YC). By virtue of the physical barrier role and surface β-glucan of YC, encapsulated pseudoviruses can be protected from gastric insult and delivered into Peyer's patches via uptake mediated by microfold cells located in the intestinal epithelium. Given the ability to carry diverse antigens, the enhanced oral delivery of pseudoviruses achieved by P-YC provides a versatile platform for the development of various oral vaccines.

Antibody- Based Immunotherapy Combined With Antimycotic Drug TMP- SMX to Treat Infection With Paracoccidioides brasiliensis

Monoclonal antibodies (mAbs) are promising alternatives to treat infectious diseases, especially given their potential for applications in combination therapies with antimicrobial drugs to enhance the antifungal efficacy. Protection mediated by mAbs used to treat experimental paracoccidioidomycosis (PCM) has been demonstrated previously. Our aim in the present work was to characterize a monoclonal antibody (mAbF1.4) raised against a cell wall glycoconjugate fraction of Paracoccidioides spp. and to analyze its efficacy combined with trimethoprim-sulfamethoxazole (TMP/SMX) as treatment for experimental PCM. We demonstrated that the epitope recognized by mAbF1.4 is consistent with branched glucose residues present on a cell wall β-glucan polymer. In vitro, mAbF1.4 increased the phagocytic capacity and nitric oxide concentration induced by the macrophage cell line J774.1A, and this resulted in a significant reduction in the viability of the opsonophagocytized yeasts. In vivo, we detected a significant reduction in pulmonary fungal burdens of mice treated with mAbF1.4 in association with TMP/SMX, which correlated with increased pulmonary concentrations (determined by ELISA) of IFN- γ, TNF-α, IL-10 and IL-17. In parallel, we observed a decrease in IL-4, suggesting that the treatment was associated with a mixed Th1-Th17 type immune response. Histopathology of lung segments from mice receiving the combination therapy showed a significant reduction in granulomas, which were well-defined, and improved maintenance of lung architecture. These findings demonstrate that mAbF1.4 + TMP/SMX therapy is a promising approach to combat PCM as well as decrease disease sequelae and highlights the potential benefits of immune mediators in PCM combined immunotherapy.

The Role of B-Cells and Antibodies against Candida Vaccine Antigens in Invasive Candidiasis

Systemic candidiasis is an invasive fungal infection caused by members of the genus Candida. The recent emergence of antifungal drug resistance and increased incidences of infections caused by non-albicans Candida species merit the need for developing immune therapies against Candida infections. Although the role of cellular immune responses in anti-Candida immunity is well established, less is known about the role of humoral immunity against systemic candidiasis. This review summarizes currently available information on humoral immune responses induced by several promising Candida vaccine candidates, which have been identified in the past few decades. The protective antibody and B-cell responses generated by polysaccharide antigens such as mannan, β-glucan, and laminarin, as well as protein antigens like agglutinin-like sequence gene (Als3), secreted aspartyl proteinase (Sap2), heat shock protein (Hsp90), hyphally-regulated protein (Hyr1), hyphal wall protein (Hwp1), enolase (Eno), phospholipase (PLB), pyruvate kinase (Pk), fructose bisphosphate aldolase (Fba1), superoxide dismutase gene (Sod5) and malate dehydrogenase (Mdh1), are outlined. As per studies reviewed, antibodies induced in response to leading Candida vaccine candidates contribute to protection against systemic candidiasis by utilizing a variety of mechanisms such as opsonization, complement fixation, neutralization, biofilm inhibition, direct candidacidal activity, etc. The contributions of B-cells in controlling fungal infections are also discussed. Promising results using anti-Candida monoclonal antibodies for passive antibody therapy reinforces the need for developing antibody-based therapeutics including anti-idiotypic antibodies, single-chain variable fragments, peptide mimotopes, and antibody-derived peptides. Future research involving combinatorial immunotherapies using humanized monoclonal antibodies along with antifungal drugs/cytokines may prove beneficial for treating invasive fungal infections.

An overview of in vitro, ex vivo and in vivo models for studying the transport of drugs across intestinal barriers

Oral administration is the most commonly used route for drug delivery owing to its cost-effectiveness, ease of administration, and high patient compliance. However, the absorption of orally delivered compounds is a complex process that greatly depends on the interplay between the characteristics of the drug/formulation and the gastrointestinal tract. In this contribution, we review the different preclinical models (in vitro, ex vivo and in vivo) from their development to application for studying the transport of drugs across intestinal barriers. This review also discusses the advantages and disadvantages of each model. Furthermore, the authors have reviewed the selection and validation of these models and how the limitations of the models can be addressed in future investigations. The correlation and predictability of the intestinal transport data from the preclinical models and human data are also explored. With the increasing popularity and prevalence of orally delivered drugs/formulations, sophisticated preclinical models with higher predictive capacity for absorption of oral formulations used in clinical studies will be needed.

Preparation of a water soluble aminated β-1,3-D-glucan for gene carrier: The in vitro study of the anti-inflammatory activity and transfection efficiency

β-1,3-D-glucan has been reported to have a series of bioactivities including antitumor, antimicrobial, anti-inflammatory and antioxidative effects; however, its insolubility in neutral aqueous solution significantly restricts the potential application in biological and medicine fields. Herein, a water-soluble aminated β-1,3-D-glucan (AG) was synthesized and the anti-inflammatory effect, cytotoxicity and plasmid DNA (pDNA) binding capacity of AG, serum stability, the particle sizes and zeta potentials of AG/pDNA nanocomposites, and the transfection efficiency and mechanism of action were studied. AG shows no obvious cytotoxicity within the range of working concentration (1-64 μg/ml) and it exerts potent anti-inflammatory effect independent on Dectin-1 and TLR2. AG/pDNA nanocomposites prepared by electrostatic interaction possess an appropriate particle size ranged from 192.8 to 118.4 nm and zeta potentials ranged from 20.880 to 27.16 mV with the N/P ratios from 5 to 100. AG/pDNA nanocomposites at the N/P ratios of 10 and 20 were able to show superior transfection efficiencies in RAW 264.7 cells as a result of their suitable particle size, zeta potential, anti-inflammatory effect, and the specific interaction with pattern recognition receptors (Dectin-1 and TLR2). These results indicate that AG is a potential candidate for DNA delivery system due to its potent anti-inflammatory effect and high transfection efficiency.

Yeast Particle Encapsulation of Scaffolded Terpene Compounds for Controlled Terpene Release

Terpenes are naturally occurring compounds produced by plants that are of great commercial interest in the food, agricultural, cosmetic, and pharmaceutical industries due to their broad spectra of antibacterial, antifungal, anthelmintic, membrane permeation enhancement, and antioxidant biological activities. Applications of terpenes are often limited by their volatility and the need for surfactants or alcohols to produce stable, soluble (non-precipitated) products. Yeast particles (YPs) are hollow, porous microspheres that have been used for the encapsulation of terpenes (YP terpenes) by passive diffusion of terpenes through the porous YP cell walls. We here report the development of a second generation YP encapsulated terpene technology that incorporates the stimuli-responsive control of terpene release using biodegradable pro-terpene compounds (YP pro-terpenes). YP terpenes and YP pro-terpenes were both produced, in which high levels of carvacrol, eugenol, thymol and geraniol were encapsulated. The YP pro-terpenes show higher encapsulation stability than YP terpenes due to pro-terpenes being non-volatile solids at room temperature and stable in suspensions at neutral pH. YP pro-terpenes and YP terpenes were evaluated for biological activity in antibacterial, antifungal and anthelmintic assays. The YP pro-terpenes retained the full biological activity of the parent terpene compound.

Yeast Cells in Microencapsulation. General Features and Controlling Factors of the Encapsulation Process

Besides their best-known uses in the food and fermentation industry, yeasts have also found application as microcapsules. In the encapsulation process, exogenous and most typically hydrophobic compounds diffuse and end up being passively entrapped in the cell body, and can be released upon application of appropriate stimuli. Yeast cells can be employed either living or dead, intact, permeabilized, or even emptied of all their original cytoplasmic contents. The main selling points of this set of encapsulation technologies, which to date has predominantly targeted food and-to a lesser extent-pharmaceutical applications, are the low cost, biodegradability and biocompatibility of the capsules, coupled to their sustainable origin (e.g., spent yeast from brewing). This review aims to provide a broad overview of the different kinds of yeast-based microcapsules and of the main physico-chemical characteristics that control the encapsulation process and its efficiency.

Glucan particles as a novel adjuvant for the induction of experimental autoimmune encephalomyelitis

For over 70 years experimental autoimmune encephalomyelitis (EAE) has been induced with myelin autoantigens emulsified in complete Freund's adjuvant (CFA) which has significant side effects such as pain, inflammation, and tissue necrosis at the injection site. β-1,3-d-glucan particles (GPs) are hollow microcapsules prepared from Saccharomyces cerevisiae cell walls that induce potent Th17 cell responses without causing strong injection site tissue reactions. We evaluated the potential of GPs complexed with neuroantigens to induce EAE while avoiding undesirable side effects. GPs loaded with myelin oligodendrocyte glycoprotein 35-55 (MOG_35-55) or proteolipid protein 139-151 (PLP_139-151) peptides effectively induced EAE in C57BL/6 mice and SJL mice. Disease severity, CNS pathology and immune responses were comparable between GP- and CFA-immunized mice. Importantly, injection with GPs resulted in significantly decreased inflammation compared with CFA. We posit that use of GPs provides an alternative means for inducing EAE that results in comparable disease, but less discomfort to animals.

Robust Immune Responses Elicited by a Hybrid Adjuvant Based on β-Glucan Particles from Yeast for the Hepatitis B Vaccine

The use of particulate adjuvants offers an interesting method for enhancing and modulating the immune responses elicited by vaccines. Aluminum salt (Alum) is one of the most important immune adjuvants approved by the Food and Drug Administration for use in humans because of its safety and efficacy, but it lacks the capacity to induce strong cellular and mucosal immune responses. In this study, we designed an antigen delivery system that combines aluminum salts with β-glucan particles. The β-glucan-aluminum particles (GP-Al) exhibited a highly uniform size of 2-4 μm and could highly specifically target antigen-presenting cells (APCs) and strongly induce dendritic cell (DC) maturation and cytokine secretion. In vivo studies showed that both WT mice and HBV-Tg mice immunized with hepatitis B surface antigen (HBsAg)-containing GP-Al displayed high anti-HBsAg IgG titers in the serum. Furthermore, in contrast to mice receiving the antigen alone, mice immunized with the particulate adjuvant exhibited IgG2a antibody titers and higher antigen-specific IFN-γ levels in splenocytes. In conclusion, we developed GP-Al microspheres to serve as a hepatitis B vaccine to enhance both humoral and cellular immune responses, representing a safe and promising system for antigen delivery.

Yeasts as a promising delivery platform for DNA and RNA vaccines

Yeasts are considered a useful system for the development of vaccines for human and veterinary health. Species such as Saccharomyces cerevisiae and Pichia pastoris have been used successfully as host organisms for the production of subunit vaccines. These organisms have been also explored as vaccine vehicles enabling the delivery of antigens such as proteins and nucleic acids. The employed species possess a GRAS status (Generally Recognized as Safe) for the production of therapeutic proteins, besides promoting immunostimulation due to the properties of their wall cell composition. This strategy allows the administration of nucleic acids orally and a specific delivery to professional antigen-presenting cells (APCs). In this review, we seek to outline the development of whole yeast vaccines (WYV) carrying nucleic acids in different approaches in the medical field, as well as the immunological aspects of this vaccine strategy. The data presented here reveal the application of this platform in promoting effective immune responses in the context of prophylactic and therapeutic approaches.

Immunotherapy based on Pythium insidiosum mycelia drives a Th1/Th17 response in mice

Pythium insidiosum is an oomycete that affects mammals, especially humans and horses, causing a difficult-to-treat disease. Typically, surgical interventions associated with antimicrobial therapy, immunotherapy, or both are the preferred treatment choices. PitiumVac® is a therapeutic vaccine prepared from the mycelial mass of P. insidiosum and is used to treat Brazilian equine pythiosis. To better understand how PitiumVac® works, we analyzed the composition of PitiumVac® and the immune response triggered by this immunotherapy in mice. We performed an enzymatic quantification that showed a total glucan content of 21.05% ± 0.94 (α-glucan, 6.37% ± 0.77 and (1,3)(1,6)-β-glucan, 14.68% ± 0.60) and mannose content of 1.39% ± 0.26; the protein content was 0.52 mg ml-1 ± 0.07 mg ml-1. Healthy Swiss mice (n = 3) were subcutaneously preimmunized with one, two, or three shots of PitiumVac®, and immunization promoted a relevant Th1 and Th17 responses compared to nonimmunization of mice. The highest cytokine levels were observed after the third immunization, principally for IFN-γ, IL-17A, IL-6, and IL-10 levels. Results of infected untreated (Pythiosis) and infected treated (Pythiosis + PVAC) mice (n = 3) showed that PitiumVac® reinforces the Th1/Th17 response displayed by untreated mice. The (1,3)(1,6)-β-glucan content can be, at least in part, related to this Th1/Th17 response.

A biomimetic yeast shell vaccine coated with layered double hydroxides induces a robust humoral and cellular immune response against tumors

Enhancing both the humoral and cellular immune response for tumor vaccination remains a challenge. Inspired by natural pathogen structures, we took β-glucan particles derived from a baker's yeast cell shell (YS) as a vaccine carrier and danger signal for dendritic cells (DCs), and coated the YS with catanionic layered double hydroxides (LDH) by electrostatic adsorption to form a biomimetic yeast cell particle (YSL). Our experimental results showed that the YSL vaccine efficiently targeted antigen-presenting cells (APCs) and remarkably enhanced antigen cross-presentation, and strongly improved the activation and maturation of DCs. Moreover, the YSL vaccine elicited an extremely high antibody titer and strong antigen-specific cytotoxic T lymphocyte together with mixed Th1/Th17 cellular immune responses and induced marked prophylactic and therapeutic effects against E.G7-OVA tumors in mouse models. These results suggest that YSL, integrating a yeast shell to mimic natural pathogens and LDH with high antigen-loading capacity and lysosome escape, is a promising tumor vaccine platform for rapid, effective and strong induction of both humoral and cellular immune responses.

Harnessing antifungal immunity in pursuit of a Staphylococcus aureus vaccine strategy

Staphylococcus aureus (S. aureus) is one of the most common bacterial infections worldwide, and antibiotic resistant strains such as Methicillin-Resistant S. aureus (MRSA) are a major threat and burden to public health. MRSA not only infects immunocompromised patients but also healthy individuals and has rapidly spread from the healthcare setting to the outside community. However, all vaccines tested in clinical trials to date have failed. Immunocompromised individuals such as patients with HIV or decreased levels of CD4+ T cells are highly susceptible to S. aureus infections, and they are also at increased risk of developing fungal infections. We therefore wondered whether stimulation of antifungal immunity might promote the type of immune responses needed for effective host defense against S. aureus. Here we show that vaccination of mice with a fungal β-glucan particle (GP) loaded with S. aureus antigens provides protective immunity to S. aureus. We generated glucan particles loaded with the four S. aureus proteins ClfA, IsdA, MntC, and SdrE, creating the 4X-SA-GP vaccine. Vaccination of mice with three doses of 4X-SA-GP promoted protection in a systemic model of S. aureus infection with a significant reduction in the bacterial burden in the spleen and kidneys. 4X-SA-GP vaccination induced antigen-specific Th1 and Th17 CD4+ T cell and antibody responses and provided long-term protection. This work suggests that the GP vaccine system has potential as a novel approach to developing vaccines for S. aureus.

Detection of Beta-Glucan Contamination in Nanotechnology-Based Formulations

Understanding the potential contamination of pharmaceutical products with innate immunity modulating impurities (IIMIs) is essential for establishing their safety profiles. IIMIs are a large family of molecules with diverse compositions and structures that contribute to the immune-mediated adverse effects (IMAE) of drug products. Pyrogenicity (the ability to induce fever) and activation of innate immune responses underlying both acute toxicities (e.g., anaphylactoid reactions or pseudoallergy, cytokine storm) and long-term effects (e.g., immunogenicity) are among the IMAE commonly related to IIMI contamination. Endotoxins of gram-negative bacteria are the best-studied IIMIs in that both methodologies for and pitfalls in their detection and quantification are well established. Additionally, regulatory guidance documents and research papers from laboratories worldwide are available on endotoxins. However, less information is currently known about other IIMIs. Herein, we focus on one such IIMI, namely, beta-glucans, and review literature and discuss the experience of the Nanotechnology Characterization Lab (NCL) with the detection of beta-glucans in nanotechnology-based drug products.

Safe-by-Design of Glucan Nanoparticles: Size Matters When Assessing the Immunotoxicity

Glucan (from Alcaligenes faecalis) is a polymer composed of β-1,3-linked glucose residues, and it has been addressed in different medical fields, namely in nanotechnology, as a vaccine or a drug delivery system. However, due to their small size, nanomaterials may present new risks and uncertainties. Thus, this work aims to describe the production of glucan nanoparticles (NPs) with two different sizes, and to evaluate the influence of the NPs size on immunotoxicity. Results showed that, immediately after production, glucan NPs presented average sizes of 129.7 ± 2.5 and 355.4 ± 41.0 nm. Glucan NPs of 130 nm presented greater ability to decrease human peripheral blood mononuclear cells and macrophage viability and to induce reactive oxygen species production than glucan NPs of 355 nm. Both NP sizes caused hemolysis and induced a higher metabolic activity in lymphocytes, although the concentration required to observe such effect was lower for the 130 nm glucan NPs. Regarding pro-inflammatory cytokines, only the larger glucan NPs (355 nm) were able to induce the secretion of IL-6 and TNF-α, probably due to their recognition by dectin-1. This higher immunomodulatory effect of the larger NPs was also observed in its ability to stimulate the production of nitric oxide (NO) and IL-1β. On the contrary, a small amount of Glu 130 NPs inhibited NO production. In conclusion, on the safe-by-design of glucan NPs, the size of the particles should be an important critical quality attribute to guarantee the safety and effectiveness of the nanomedicine.

Glucan particles as suitable carriers for the natural anti-inflammatory compounds curcumin and diplacone - Evaluation in an ex vivo model

Natural compounds offer a wide spectrum of potential active substances, but often they have a poor bioavailability. To increase the bioavailability and bioactivity of the natural anti-inflammatory molecules curcumin and diplacone, we used glucan particles (GPs), hollow shells from Saccharomyces cerevisiae composed mainly of β-1,3-d-glucan. Their indigestibility and relative stability in the gut combined with their immunomodulatory effects makes them promising carriers for such compounds. This study aimed to determine how curcumin and diplacone, either alone or incorporated in GPs, affect the immunomodulatory activity of the latter by assessing the respiratory burst response and the secretion of pro-inflammatory cytokines by primary porcine innate immune cells. Incorporating curcumin and diplacone into GPs by controlled evaporation of the organic solvent substantially reduced the respiratory burst response mediated by GPs. Incorporated curcumin in GPs also reduced GPs mediated secretion of IL-1β and TNF-α by innate immune cells. The obtained results indicate a potentially beneficial effect of the incorporation of curcumin or diplacone into GPs against inflammation.

Carbohydrate Conjugates in Vaccine Developments

Vaccines are powerful tools that can activate the immune system for protection against various diseases. As carbohydrates can play important roles in immune recognition, they have been widely applied in vaccine development. Carbohydrate antigens have been investigated in vaccines against various pathogenic microbes and cancer. Polysaccharides such as dextran and β-glucan can serve as smart vaccine carriers for efficient antigen delivery to immune cells. Some glycolipids, such as galactosylceramide and monophosphoryl lipid A, are strong immune stimulators, which have been studied as vaccine adjuvants. In this review, we focus on the current advances in applying carbohydrates as vaccine delivery carriers and adjuvants. We will discuss the examples that involve chemical modifications of the carbohydrates for effective antigen delivery, as well as covalent antigen-carbohydrate conjugates for enhanced immune responses.

A Novel Strategy for Treating Inflammatory Bowel Disease by Targeting Delivery of Methotrexate through Glucan Particles

Therapy of inflammatory bowel disease (IBD) has been a difficult task in the medical field. There is a great clinical need for more effective treatments for IBD. Herein, a targeted oral delivery system of yeast glucan particles (YGPs) carrying a clinically used anti-inflammatory drug methotrexate (MTX) to the inflamed sites in IBD mice for therapy is reported. In the findings, MTX is effectively loaded into YGPs through re-precipitation followed by gelation reaction of alginate to obtain the composite YGPs/MTX, which are internalized into RAW264.7 macrophage cells through dectin-1 and CR3 receptors. Furthermore, YGPs/MTX can suppress the proliferation of macrophage cells efficiently, leading to down-regulation of pro-inflammatory cytokines induced by lipopolysaccharides. Additionally, YGPs accumulate in the inflammation site of colitis mice, enabling YGPs/MTX to target the inflammatory site, significantly improve the efficacy of MTX, and reduce the cytotoxicity of MTX. Therefore, the YGPs-based drug delivery system provides a new strategy for MTX application in the clinical treatment of IBD.

β-glucan and anisodamine can enhance the immersion immune efficacy of inactivated cyprinid herpesvirus 2 vaccine in Carassius auratus gibelio

As one of the most important fish in freshwater aquaculture, gibel carp (Carassius auratus gibelio) is easily susceptible to Cyprinid herpesvirus 2 (CyHV-2). Immersion vaccination has attracted many researchers due to its simple operation in preventing infectious diseases. However, the unavoidable disadvantage is that the immersion vaccine must be used with adjuvants to get a better performance. In this study, gibel carps were vaccinated by a 60 min bath in a β-propiolactone-inactivated Cyprinid herpesvirus 2, mixed with DTT, β-glucan, anisodamine and scopolamine, respectively. After immunization, the fishs were challenged by CyHV-2 in 2 weeks. By analyzing pathological section, we found that β-glucan, anisodamine and scopolamine groups protected the gibel carp compared to the control group, which was consistent with the trend of survival rate. Specifically, β-glucan group in serum appeared best on lysozyme, TSOD and complement C3. Real time quantitative RT-PCR results demonstrated that in both spleen and head kidney tissues, mRNA expressions of typical Th1 immune response cytokines IL-2 and IFN-γ2 in β-glucan group and anisodamine group were significantly higher than other groups and the level of immunoglobulins related to systemic immunity (IgM) and mucosal immunity (IgZ) were also enhanced in the immune period. DTT group slightly affected immune gene and serum enzyme activity, while did not show an adjuvant effect on survival rate. In addition, four adjuvant groups could obviously inhibit CyHV-2 replication. This study explored and proved the good efficiency of β-glucan or anisodamine as immersion immune adjuvant and also provided reference for improving the efficiency of immersion immunity.

Encapsulation of poorly soluble drugs in yeast glucan particles by spray drying improves dispersion and dissolution properties

In this work, novel amorphous solid dispersions based on yeast glucan particles were produced. Yeast glucan particles are hollow and porous, and they are mainly composed of amorphous polysaccharides. We hypothesized that these particles are suitable candidates for the amorphization of drugs with low water solubility. Model drugs ibuprofen and curcumin were successfully encapsulated in glucan particles by spray drying. Different spray-drying parameters were tested to evaluate the influence of atomizing droplet size and initial solid content on encapsulation efficiency. It was shown that higher solid content and, more significantly, larger droplet sizes lead to higher encapsulation efficiencies. The encapsulation efficiency of ibuprofen (10 wt%) into glucan particles was considerably improved from 41.3 ± 0.5% to 64.3 ± 0.2% by increasing initial solid content and droplet size with the two-fluid nozzle. The spray drying process was further optimized by using the ultrasonic nozzle and it was possible to achieve complete encapsulation of ibuprofen and curcumin without any precipitation of the active compound outside of the glucan particles. Overall, it was possible to produce completely amorphous composites with outstanding wettability and dispersion properties, and with significantly faster dissolution rates when compared to the micronized crude drug.

β-glucan as a new tool in vaccine development

Vaccination constitutes one of the major breakthroughs in human medicine. At the same time, development of more immunogenic vaccine alternatives to using aluminium-based adjuvants is one of the most important phases of vaccination development. Among different sources of carbohydrate polymers, including plants, microbes and synthetic sources tested, glucans were found to be the most promising vaccine adjuvant, as they alone stimulate various immune reactions including antibody production without any negative side effects. The use of glucan particles as a delivery system is a viable option based on the documented efficient antigen loading and receptor-targeted uptake in antigen-presenting cells. In addition to particles, soluble glucans can be used as novel hydrogels or as direct immunocyte-targeting delivery systems employing novel complexes with oligodeoxynucleotides. This review focuses on recent advances in glucan-based vaccine development from glucan-based conjugates to a glucan-based delivery and adjuvant platform.

Protection of mice against experimental cryptococcosis using glucan particle-based vaccines containing novel recombinant antigens

Meningitis due to Cryptococcus neoformans is responsible for upwards of 180,000 deaths worldwide annually, mostly in immunocompromised individuals. Currently there are no licensed fungal vaccines, and even with anti-fungal drug treatment, cryptococcal meningitis is often fatal. Our lab previously demonstrated vaccination with recombinant cryptococcal proteins delivered in glucan particles (GPs) protects mice against an otherwise lethal infection. The aim of the present study was to discover additional cryptococcal antigens affording vaccine-mediated protection. Sixteen proteins, each with evidence of extracellularity, were selected for in vivo testing based on their abundance in protective alkaline extracts of an acapsular C. neoformans strain, their known immunogenicity, and/or their high transcript level during human infection. Candidate antigens were recombinantly expressed in E. coli, purified and loaded into GPs. BALB/c and C57BL/6 mice received three subcutaneous injections of GP-based vaccine, and survival was assessed for 84 days following a lethal orotracheal challenge with strain KN99. As with our six published GP-vaccines, we saw differences in overall protection between mouse strains such that BALB/c mice typically demonstrated better survival than C57BL/6 mice. From these studies, we identified seven new proteins which, when administered as GP-vaccines, protect BALB/c and/or C57BL/6 mice against cryptococcal infection. With these results, we expand the pool of novel protective antigens to eleven proteins and demonstrate the potential for selection of highly transcribed extracellular proteins as vaccine targets. These screens highlight the efficacy of GP-subunit vaccines and identify promising antigens for further testing in anti-cryptococcal, multi-epitope vaccine formulations.

A novel vaccine platform using glucan particles for induction of protective responses against Francisella tularensis and other pathogens

Vaccines are considered the bedrock of preventive medicine. However, for many pathogens, it has been challenging to develop vaccines that stimulate protective, long-lasting immunity. We have developed a novel approach using β-1,3-D-glucans (BGs), natural polysaccharides abundantly present in fungal cell walls, as a biomaterial platform for vaccine delivery. BGs simultaneously provide for receptor-targeted antigen delivery to specialized antigen-presenting cells together with adjuvant properties to stimulate antigen-specific and trained non-specific immune responses. This review focuses on various approaches of using BG particles (GPs) to develop bacterial and fungal vaccine candidates. A special case history for the development of an effective GP tularaemia vaccine candidate is highlighted.

Use of Biopolymers in Mucosally-Administered Vaccinations for Respiratory Disease

Communicable respiratory infections are the cause of a significant number of infectious diseases. The introduction of vaccinations has greatly improved this situation. Moreover, adjuvants have allowed for vaccines to be more effective with fewer adverse side effects. However, there is still space for improvement because while the more common injected formulations induce a systematic immunity, they do not confer the mucosal immunity needed for more thorough prevention of the spread of respiratory disease. Intranasal formulations provide systemic and mucosal immune protection, but they have the potential for more serious side effects and a less robust immune response. This review looks at seven different adjuvants—chitosan, starch, alginate, gellan, β-glucan, emulsan and hyaluronic acid—and their prospective ability to improve intranasal vaccines as adjuvants and antigen delivery systems.

Curcumin encapsulation in yeast glucan particles promotes its anti-inflammatory potential in vitro

Glucan particles (GPs) from Saccharomyces cerevisiae are hollow shells that are composed mainly of β-1,3-d-glucan, which has demonstrated immunomodulatory and anti-inflammatory potential both in vitro and in vivo. Curcumin is a natural hydrophobic phenolic compound, which possesses a significant anti-inflammatory effect and is used as supportive therapy in the treatment of many inflammatory diseases. The aim of this study is to evaluate the possible synergic effect and other benefits of the co-application of GPs and curcumin in the form of pharmaceutical composites. GP/curcumin composites were prepared using controlled evaporation of the organic solvent and their anti-oxidative effect and anti-inflammatory potential were tested on THP1‑XBlue™‑MD2‑CD14 human monocytes cell line. The anti-oxidative effect was measured on pyocyanin-stimulated cells in vitro and the NF-κB/AP-1 signaling pathway on lipopolysaccharide pre-treated monocytes was chosen for anti-inflammatory assays. The secretion of pro-inflammatory cytokines TNF-α and IL-1β was evaluated as well. Results mostly showed a pro-oxidative activity of empty GPs, however, pharmaceutical composites demonstrated an anti-oxidative effect. The activity of NF-κB/AP-1 was substantially decreased by the tested GP/curcumin composites, which also caused the attenuation of cytokines secretion. The obtained results indicate a beneficial effect of the incorporation of curcumin into GPs.

Glucan Particles Are a Powerful Adjuvant for the HBsAg, Favoring Antiviral Immunity

The lack of vaccine adjuvants that are able to induce robust T cell responses fosters the search for more powerful options. Pathogen-like particles are a promising approach. The adjuvant activity of pathogen-like particles is highly influenced by size and surface composition. This study aimed to evaluate the adjuvant potential of two different β-glucan-based particles, blend chitosan/β-glucan particles (ChiGluPs), which are positively charged and have mean size of 1276 nm, and neutral yeast-derived glucan particles (GPs), with a mean size of 3 μm. Additionally, chitosan particles (ChiPs) were used to understand the effect of β-glucan addition (ChiGluPs). Mouse spleen cells responded through the production of either TNF-α or RANTES, following in vitro stimulation with particles containing either β-glucan (ChiGluPs and GPs) or chitosan (ChiGluPs and ChiPs). Human monocytes responded to all particles through TNF-α secretion. Subcutaneous vaccination of mice with the hepatitis B surface antigen (HBsAg) showed increased serum IgG for all particles compared to HBsAg alone (435-, 4500-, or 2500-fold increase for either ChiPs, ChiGluPs, or GPs). Interestingly, only GPs elicited the secretion of HBsAg-specific Th1, Th2, Th9, Th17, Th22, and Treg-related cytokines. This study demonstrates, for the first time, that GPs can have a significant role against the hepatitis B virus by favoring antiviral immunity.

β-Glucan successfully stimulated the immune system in different jawed vertebrate species

Several reports have shown the positive effects of β-glucans on the immune. Howeverthese studies have a broad experimental design including β-glucans compounds. Consequently, a study using the same β-glucan molecule, administration route and experimental design is needed to compare the effects of β-glucan across vertebrate species. For this end, during 28 days we fed four different vertebrate species: mice, dogs, piglets and chicks, with two β-glucan molecules (BG01 and BG02). We measured the serum interleukin 2 as an indicator of innate immune response, the neutrophils and monocytes phagocytosis index as a cellular response and antibody formation as an adaptive response. The results clearly showed that the different β-glucan molecules exhibited biologically differently behaviors, but both molecules stimulate the immune system in a similar pattern in these four species. This finding suggests that vertebrates shared similar mechanisms/patterns in recognizing the β-glucans and confirms the benefits of β-glucans across different vertebrate species.

Protection induced by a Francisella tularensis subunit vaccine delivered by glucan particles

Francisella tularensis is an intracellular pathogen causing the disease tularemia, and an organism of concern to biodefence. There is no licensed vaccine available. Subunit approaches have failed to induce protection, which requires both humoral and cellular immune memory responses, and have been hampered by a lack of understanding as to which antigens are immunoprotective. We undertook a preliminary in silico analysis to identify candidate protein antigens. These antigens were then recombinantly expressed and encapsulated into glucan particles (GPs), purified Saccharomyces cerevisiae cell walls composed primarily of β-1,3-glucans. Immunological profiling in the mouse was used to down-selection to seven lead antigens: FTT1043 (Mip), IglC, FTT0814, FTT0438, FTT0071 (GltA), FTT0289, FTT0890 (PilA) prior to transitioning their evaluation to a Fischer 344 rat model for efficacy evaluation. F344 rats were vaccinated with the GP protein antigens co-delivered with GP-loaded with Francisella LPS. Measurement of cell mediated immune responses and computational epitope analysis allowed down-selection to three promising candidates: FTT0438, FTT1043 and FTT0814. Of these, a GP vaccine delivering Francisella LPS and the FTT0814 protein was able to induce protection in rats against an aerosol challenge of F. tularensis SchuS4, and reduced organ colonisation and clinical signs below that which immunisation with a GP-LPS alone vaccine provided. This is the first report of a protein supplementing protection induced by LPS in a Francisella vaccine. This paves the way for developing an effective, safe subunit vaccine for the prevention of inhalational tularemia, and validates the GP platform for vaccine delivery where complex immune responses are required for prevention of infections by intracellular pathogens.

Synergistic effect of dual targeting vaccine adjuvant with aminated β-glucan and CpG-oligodeoxynucleotides for both humoral and cellular immune responses

Presently, clinically approved adjuvants (such as aluminum salts) fail to induce cellular immune responses, which is crucial to defend against intracellular pathogens (including HIV, malaria, tuberculosis and Ebola) and cancer. However, Freund's complete adjuvant potently stimulates both humoral and cellular immune responses, accompanying by high toxicity and severe side reactions. Here in this work, a CpG-oligodeoxynucleotides (CpG-OND) crosslinked aminated β-glucan-Ovalbumin dual targeting nanoparticle (CpG-OND-AG-OVA) is prepared through a simple and mild ionic complexation method. The aminated β-glucan plays dual roles as antigen presenting cells (APCs) targeted carrier and immunopotentiator (targeting and activating dectin-1 on APCs). Meanwhile, CpG-OND also plays dual roles as ionic crosslinker and immunopotentiator (targeting and activating Toll-like receptor 9 in APCs). The adjuvant activity of the particles is evaluated through in vitro and in vivo experiments. The particles significantly enhance uptake and sustained proteolytic processing of antigens, and result in APCs maturation, inducing robust Th1 and Th2-type immune responses comparable to Freund's adjuvant without obvious toxicity. The potent adjuvant activity of the nanoparticles may originate from dual targeting synergistic effects between aminated β-glucan and CpG-OND. Accordingly, the dual targeting nanoparticles may be a promising vaccine adjuvant for inducing robust humoral and cellular immune responses against infectious diseases and cancers.

STATEMENT OF SIGNIFICANCE

An ideal adjuvant for subunit vaccine should act as both a carrier to enhance the uptake, sustained processing and cytosolic delivery of antigens, and an immunopotentiator to stimulate antigen presenting cells (APCs) for activation of naive T cells. Additionally, it should be easy to obtain and safe with negligible toxicity. Unfortunately, both synthetic and natural polymers that have been developed into antigen delivery system cannot completely fulfill the requirements. In the present study, the authors design nanoparticles with aminated β-glucan and CpG-oligodeoxynucleotides (CpG-OND) through a simple and mild method. β-Glucan (a dectin-1 and TLR2 targeted PAMP) and CpG-OND (a TLR9 targeted PAMP) are readily accessible. Aminated β-glucan plays dual roles in the nanoparticle as APCs targeted carrier and immunopotentiator. Meanwhile, CpG-OND also plays dual roles as crosslinker and APCs targeted immunopotentiator. By making use of synergistic effect of the dual targeting vaccine adjuvant with aminated β-glucan and CpG-OND, the nanoparticles induce robust antigen specific immune responses comparable to Freund's adjuvant without obvious toxicity.

Chitosan:β-glucan particles as a new adjuvant for the hepatitis B antigen

The development of new vaccine adjuvants is urgently needed not only to enable new routes of vaccine administration but mostly to go beyond protective humoral immunity, often insufficient to fight infectious diseases. The association of two or more immunopotentiators or mimicking pathogen physicochemical properties are strategies that can favor powerful and more balanced Th1/Th2 immune responses. Therefore, the present work aimed to combine both chitosan and β-glucan biopolymers in the same particle, preferably with surface β-glucan localization to simulate the cell wall of some pathogens and to stimulate the immune cells expressing the Dectin-1 receptor. Chitosan:β-glucan particles (ChiGluPs) were developed through a chitosan precipitation method. The chitosan was precipitated into a β-glucan alkaline solution followed by genipin crosslink. The optimized method produced particles with a mean diameter of 837 nm for ChiPs and 1274 nm for ChiGluPs. β-glucan surface location was confirmed by zeta potential measurements (+24 mV for ChiGluPs and +36 mV for ChiPs) and zeta potential titration. These new particles showed high antigen loading efficacy and low cytotoxicity. Mice vaccination studies revealed that both ChiPs and ChiGluPs had an adjuvant effect for the hepatitis B surface antigen (HBsAg), with ChiGluPs resulting in serum anti-HBsAg total IgG 16-fold higher than ChiPs, when administered with 1.5 µg HBsAg per dose. Specifically, IgG1 subclass was 5-fold higher and IgG3 subclass was 4-fold higher for ChiGluPs comparing to ChiPs. Overall, the preparation method developed allowed the advantageous combination of β-glucan with chitosan, without chemical functionalization, which represents an additional step toward tailor-made adjuvants production using simple precipitation techniques.

Entrapping of Nanoparticles in Yeast Cell Wall Microparticles for Macrophage-Targeted Oral Delivery of Cabazitaxel

In this work, a nano-in-micro carrier was constructed by loading polymer-lipid hybrid nanoparticles (NPs) into porous and hollow yeast cell wall microparticles (YPs) for macrophage-targeted oral delivery of cabazitaxel (CTX). The YPs, primarily composed of natural β-1,3-d-glucan, can be recognized by the apical membrane receptor, dectin-1, which has a high expression on macrophages and intestinal M cells. By combining electrostatic force-driven self-deposition with solvent hydration/lyophilization methods, the positively charged NPs loaded with CTX or fluorescence probes were efficiently packaged into YPs, as verified by scanning electron microscope (SEM), atomic force mircoscope (AFM), and confocal laser scanning microscopy (CLSM) images. NP-loaded YPs (NYPs) showed a slower in vitro drug release and higher drug stability compared with NPs in a simulated gastrointestinal environment. Biodistribution experiments confirmed a widespread distribution and extended retention time of NYPs in the intestinal tract after oral administration. Importantly, a large amount of NYPs were primarily accumulated and transported in the intestinal Peyer's patches as visualized in distribution and absorption site studies, implying that NYPs were mainly absorbed through the lymphatic pathway. In vitro cell evaluation further demonstrated that NYPs were rapidly and efficiently taken up by macrophages via receptor dectin-1-mediated endocytosis using a mouse macrophage RAW 264.7 cell line. As expected, in the study of in vivo pharmacokinetics, the oral bioavailability of CTX was improved to 32.1% when loaded in NYPs, which is approximately 5.7 times higher than that of the CTX solution, indicating the NYPs are efficient for oral targeted delivery. Hence, this nano-in-micro carrier is believed to become a hopeful alternative strategy for increasing the oral absorption of small molecule drugs.