Quillaja brasiliensis saponin-based nanoparticulate adjuvants are capable of triggering early immune responses

Adjuvant-driven antibody response to use cows as biofactories of anti-SARS-CoV-2 neutralizing antibodies in colostrum

Cows produce a substantial amount of immunoglobulin in the colostrum, and nutraceutical products derived from these antibodies are gaining attention for their potential role in human viral disease prevention. The objective of our study was to develop an immunization schedule for pregnant cows to produce hyperimmune colostrum with antibodies presenting high avidity and neutralizing activity against SARS-CoV-2. The recombinant spike receptor-binding domain (RBD) from SARS-CoV-2, expressed using the Expi293F system and purified via Ni-affinity chromatography, was solubilized in (1) saponin (QuilA) or (2) a suspension of potassium and aluminum hydroxide (Alum). Vaccination of pregnant cows and serum sample collection were performed 45, 30, and 15 d before the expected calving date. Serum and colostrum were also collected on the day of parturition. Anti-RBD IgG, IgG1, and IgG2 production, viral neutralization, and antibody avidity were evaluated by ELISA. Cows immunized with recombinant RBD with the QuilA adjuvant produced higher amounts of all antibody subclasses than cows in the Alum group. The viral neutralization index from serum samples was also higher in the QuilA group. Significant differences were not observed in the avidity of antibodies, except for that of IgG2, which was higher in the serum of cows receiving the Alum formulation. As the IgG1 antibody subclass and its avidity are crucial for SARS-CoV-2 neutralization, QuilA might be the optimal adjuvant for producing hyperimmune colostrum in cows. These findings support the use of cows as biofactories of neutralizing antibodies against SARS-CoV-2 or any future emerging and re-emerging viral diseases, with the possibility of simply substituting the subunit antigen in the vaccine formulation. Further tests must be done to evaluate the efficacy of using hyperimmune colostrum as a nutraceutical or purified bovine antibodies as a pharmacological approach for COVID-19 prevention.

Application of plant-derived products as adjuvants for immune activation and vaccine development

Vaccines are one of the most important means to prevent and control the epidemic of infectious diseases. Commercial vaccines not only include corresponding antigens, but also need vaccine adjuvants. Immune adjuvants play an increasingly important role in the research, development and manufacture of vaccines. Adjuvants combined with antigens can improve the stability, safety and immune efficiency of vaccines. Some substances that can enhance the immune response have been found in nature(mainly plants) and used as adjuvants in vaccines to improve the immune effect of vaccines. These plant-derived immune adjuvants often have the advantages of low toxicity, high stability, low price, etc., providing more possibilities for vaccine development. We summarized and analyzed the advantages, application research, particulate delivery systems, existing problems and future research focus of botanical adjuvant. It is hoped to provide new ideas for the research and development of immune adjuvants in the future.

The development of a human Brucella mucosal vaccine: What should be considered?

Brucellosis is a chronic infectious disease that is zoonotic in nature. Brucella can infect humans through interactions with livestock, primarily via the digestive tract, respiratory tract, and oral cavity. This bacterium has the potential to be utilized as a biological weapon and is classified as a Category B pathogen by the Centers for Disease Control and Prevention. Currently, there is no approved vaccine for humans against Brucella, highlighting an urgent need for the development of a vaccine to mitigate the risks posed by this pathogen. Brucella primarily infects its host by adhering to and penetrating mucosal surfaces. Mucosal immunity plays a vital role in preventing local infections, clearing microorganisms from mucosal surfaces, and inhibiting the spread of pathogens. As mucosal vaccine strategies continue to evolve, the development of a safe and effective mucosal vaccine against Brucella appears promising.This paper reviews the immune mechanism of mucosal vaccines, the infection mechanism of Brucella, successful Brucella mucosal vaccines in animals, and mucosal adjuvants. Additionally, it elucidates targeting and optimization strategies for mucosal vaccines to facilitate the development of human vaccines against Brucella.

Impact of inorganic/organic nanomaterials on the immune system for disease treatment

The study of nanomaterials' nature, function, and biocompatibility highlights their potential in drug delivery, imaging, diagnostics, and therapeutics. Advancements in nanotechnology have fostered the development and application of diverse nanomaterials. These materials facilitate drug delivery and influence the immune system directly. Yet, understanding of their impact on the immune system is incomplete, underscoring the need to select materials to achieve desired outcomes carefully. In this review, we outline and summarize the distinctive characteristics and effector functions of inorganic nanomaterials and organic materials in inducing immune responses. We highlight the role and advantages of nanomaterial-induced immune responses in the treatment of immune-related diseases. Finally, we briefly discuss the current challenges and future opportunities for disease treatment and clinical translation of these nanomaterials.

Intranasal Delivery of Quillaja brasiliensis Saponin-Based Nanoadjuvants Improve Humoral Immune Response of Influenza Vaccine in Aged Mice

Increasing the effectiveness of vaccines against respiratory viruses is particularly relevant for the elderly, since they are prone to develop serious infections due to comorbidities and the senescence of the immune system. The addition of saponin-based adjuvants is an interesting strategy to increase the effectiveness of vaccines. We have previously shown that ISCOM matrices from Q. brasiliensis (IMXQB) are a safe and potent adjuvant. In this study, we evaluated the use of IMXQB as an adjuvant for the seasonal trivalent influenza vaccine (TIV) in an aged mice model. Herein, we show that subcutaneous injection of the adjuvanted vaccine promoted higher titers of IgM, IgG (and isotypes), and serum hemagglutination inhibition titers (HAI). Notably, aged mice immunized by intranasal route also produced higher IgG (and isotypes) and IgA titers up to 120 days after priming, as well as demonstrating an improvement in the HAI antibodies against the TIV. Further, experimental infected aged mice treated once with sera from adult naïve mice previously immunized with TIV-IMXQB subcutaneously successfully controlled the infection. Overall, TIV-IMXQB improved the immunogenicity compared to TIV by enhancing systemic and mucosal immunity in old mice conferring a faster recovery after the H1N1pdm09-like virus challenge. Thus, IMXQB nanoparticles may be a promising platform for next-generation viral vaccines.

Three immunizations with Novavax's protein vaccines increase antibody breadth and provide durable protection from SARS-CoV-2

The immune responses to Novavax's licensed NVX-CoV2373 nanoparticle Spike protein vaccine against SARS-CoV-2 remain incompletely understood. Here, we show in rhesus macaques that immunization with Matrix-MTM adjuvanted vaccines predominantly elicits immune events in local tissues with little spillover to the periphery. A third dose of an updated vaccine based on the Gamma (P.1) variant 7 months after two immunizations with licensed NVX-CoV2373 resulted in significant enhancement of anti-spike antibody titers and antibody breadth including neutralization of forward drift Omicron variants. The third immunization expanded the Spike-specific memory B cell pool, induced significant somatic hypermutation, and increased serum antibody avidity, indicating considerable affinity maturation. Seven months after immunization, vaccinated animals controlled infection by either WA-1 or P.1 strain, mediated by rapid anamnestic antibody and T cell responses in the lungs. In conclusion, a third immunization with an adjuvanted, low-dose recombinant protein vaccine significantly improved the quality of B cell responses, enhanced antibody breadth, and provided durable protection against SARS-CoV-2 challenge.

ISCOMs/MPLA-Adjuvanted SDAD Protein Nanoparticles Induce Improved Mucosal Immune Responses and Cross-Protection in Mice

The epidemics caused by the influenza virus are a serious threat to public health and the economy. Adding appropriate adjuvants to improve immunogenicity and finding effective mucosal vaccines to combat respiratory infection at the portal of virus entry are important strategies to boost protection. In this study, a novel type of core/shell protein nanoparticle consisting of influenza nucleoprotein (NP) as the core and NA1-M2e or NA2-M2e fusion proteins as the coating antigens by SDAD hetero-bifunctional crosslinking is exploited. Immune-stimulating complexes (ISCOMs)/monophosphoryl lipid A (MPLA) adjuvants further boost the NP/NA-M2e SDAD protein nanoparticle-induced immune responses when administered intramuscularly. The ISCOMs/MPLA-adjuvanted protein nanoparticles are delivered through the intranasal route to validate the application as mucosal vaccines. ISCOMs/MPLA-adjuvanted nanoparticles induce significantly strengthened antigen-specific antibody responses, cytokine-secreting splenocytes in the systemic compartment, and higher levels of antigen-specific IgA and IgG in the local mucosa. Meanwhile, significantly expanded lung resident memory (RM) T and B cells (TRM /BRM ) and alveolar macrophages population are observed in ISCOMs/MPLA-adjuvanted nanoparticle-immunized mice with a 100% survival rate after homogeneous and heterogeneous H3N2 viral challenges. Taken together, ISCOMs/MPLA-adjuvanted protein nanoparticles could improve strong systemic and mucosal immune responses conferring protection in different immunization routes.

The innate effects of plant secondary metabolites in preclusion of gynecologic cancers: Inflammatory response and therapeutic action

Gynecologic cancers can make up the bulk of cancers in both humans and animals. The stage of diagnosis and the type of tumor, its origin, and its spread are a few of the factors that influence how effectively a treatment modality works. Currently, radiotherapy, chemotherapy, and surgery are the major treatment options recommended for the eradication of malignancies. The use of several anti-carcinogenic drugs increases the chance of harmful side effects, and patients might not react to the treatments as expected. The significance of the relationship between inflammation and cancer has been underscored by recent research. As a result, it has been shown that a variety of phytochemicals with beneficial bioactive effects on inflammatory pathways have the potential to act as anti-carcinogenic medications for the treatment of gynecologic cancer. The current paper reviews the significance of inflammatory pathways in gynecologic malignancies and discusses the role of plants-derived secondary metabolites that are useful in the treatment of cancer.

Evaluation of immunological adjuvant activities of saponin rich fraction from the fruits of Asparagus adscendens Roxb. with less adverse reactions

The hemolytic activity, in vitro as well as in vivo toxicity, and immunomodulatory potential of saponins-rich fraction of Asparagus adscendens Roxb. fruit (AA-SRF) have been assessed in this study in order to explore AA-SRF as an alternative safer adjuvant to standard Quil-A saponin. The AA-SRF showed lower hemolytic activity (HD₅₀ = 301.01 ± 1.63 µg/ml) than Quil-A (HD₅₀ = 17.15 ± 2.12 µg/ml). The sulforhodamine B assay also revealed that AA-SRF was less toxic to VERO cells (IC₅₀≥200 ± 4.32 µg/ml) than Quil-A (IC₅₀ = 60 ± 2.78 µg/ml). The AA-SRF did not lead to mortality in mice up to 1.6 mg and was much safer than Quil-A for in vivo use. Conversely, mice were subcutaneously immunized with OVA 100 μg alone or along with Alum (200 μg) or Quil-A (10 μg) or AA-SRF (50 μg/100 μg/200 μg) on days 0 and 14. The AA-SRF at 100 μg dose best supported the LPS/Con A primed splenocyte proliferation activity, elevated the serum OVA-specific total IgG antibody, IL-12, CD4 titer and upsurged CD3/CD19 expression in spleen as well as lymph node sections which in turn advocated its adjuvant potential. Thus, AA-SRF can be further studied for use as a safe alternative adjuvant in vaccines.

Vaccine development for bacterial pathogens: Advances, challenges and prospects

The advent and use of antimicrobials have played a key role in treating potentially life-threatening infectious diseases, improving health, and saving the lives of millions of people worldwide. However, the emergence of multidrug resistant (MDR) pathogens has been a significant health challenge that has compromised the ability to prevent and treat a wide range of infectious diseases that were once treatable. Vaccines offer potential as a promising alternative to fight against antimicrobial resistance (AMR) infectious diseases. Vaccine technologies include reverse vaccinology, structural biology methods, nucleic acid (DNA and mRNA) vaccines, generalised modules for membrane antigens, bioconjugates/glycoconjugates, nanomaterials and several other emerging technological advances that are offering a potential breakthrough in the development of efficient vaccines against pathogens. This review covers the opportunities and advancements in vaccine discovery and development targeting bacterial pathogens. We reflect on the impact of the already-developed vaccines targeting bacterial pathogens and the potential of those currently under different stages of preclinical and clinical trials. More importantly, we critically and comprehensively analyse the challenges while highlighting the key indices for future vaccine prospects. Finally, the issues and concerns of AMR for low-income countries (sub-Saharan Africa) and the challenges with vaccine integration, discovery and development in this region are critically evaluated.

Vaccine-like nanomedicine for cancer immunotherapy

The successful clinical application of immune checkpoint blockade (ICB) and chimeric antigen receptor T cells (CAR-T) therapeutics has attracted extensive attention to immunotherapy, however, their drawbacks such as limited specificity, persistence and toxicity haven't met the high expectations on efficient cancer treatments. Therapeutic cancer vaccines which instruct the immune system to capture tumor specific antigens, generate long-term immune memory and specifically eliminate cancer cells gradually become the most promising strategies to eradicate tumor. However, the disadvantages of some existing vaccines such as weak immunogenicity and in vivo instability have restricted their development. Nanotechnology has been recently incorporated into vaccine fabrication and exhibited promising results for cancer immunotherapy. Nanoparticles promote the stability of vaccines, as well as enhance antigen recognition and presentation owing to their nanometer size which promotes internalization of antigens by phagocytic cells. The surface modification with targeting units further permits the delivery of vaccines to specific cells. Meanwhile, nanocarriers with adjuvant effect can improve the efficacy of vaccines. In addition to classic vaccines composed of antigens and adjuvants, the nanoparticle-mediated chemotherapy, radiotherapy and certain other therapeutics could induce the release of tumor antigens in situ, which therefore effectively simulate antitumor immune responses. Such vaccine-like nanomedicine not only kills primary tumors, but also prevents tumor recurrence and helps eliminate metastatic tumors. Herein, we introduce recent developments in nanoparticle-based delivery systems for antigen delivery and in situ antitumor vaccination. We will also discuss the remaining opportunities and challenges of nanovaccine in clinical translation towards cancer treatment.

Astragalus Saponins, Astragaloside VII and Newly Synthesized Derivatives, Induce Dendritic Cell Maturation and T Cell Activation

Astragaloside VII (AST VII), a triterpenic saponin isolated from Astragalus species, shows promise as a vaccine adjuvant, as it supported a balanced Th1/Th2 immune response in previous in vivo studies. However, the underlying mechanisms of its adjuvant activity have not been defined. Here, we investigated the impact of AST VII and its newly synthesized semi-synthetic analogs on human whole blood cells, as well as on mouse bone marrow-derived dendritic cells (BMDCs). Cells were stimulated with AST VII and its derivatives in the presence or absence of LPS or PMA/ionomycin and the secretion of cytokines and the expression of activation markers were analyzed using ELISA and flow cytometry, respectively. AST VII and its analogs increased the production of IL-1β in PMA/ionomycin-stimulated human whole blood cells. In LPS-treated mouse BMDCs, AST VII increased the production of IL-1β and IL-12, and the expression of MHC II, CD86, and CD80. In mixed leukocyte reaction, AST VII and derivatives increased the expression of the activation marker CD44 on mouse CD4+ and CD8+ T cells. In conclusion, AST VII and its derivatives strengthen pro-inflammatory responses and support dendritic cell maturation and T cell activation in vitro. Our results provide insights into the mechanisms of the adjuvant activities of AST VII and its analogs, which will be instrumental to improve their utility as a vaccine adjuvant.

Vaccines, Adjuvants and Key Factors for Mucosal Immune Response

Vaccines are the most effective tool to control infectious diseases, which provoke significant morbidity and mortality. Most vaccines are administered through the parenteral route and can elicit a robust systemic humoral response, but they induce a weak T-cell-mediated immunity and are poor inducers of mucosal protection. Considering that most pathogens enter the body through mucosal surfaces, a vaccine that elicits protection in the first site of contact between the host and the pathogen is promising. However, despite the advantages of mucosal vaccines as good options to confer protection on the mucosal surface, only a few mucosal vaccines are currently approved. In this review, we discuss the impact of vaccine administration in different mucosal surfaces; how appropriate adjuvants enhance the induction of protective mucosal immunity and other factors that can influence the mucosal immune response to vaccines. This article is protected by copyright. All rights reserved.

Formulation of IMXQB: Nanoparticles Based on Quillaja brasiliensis Saponins to be Used as Vaccine Adjuvants

Adjuvants are essential components of subunit, recombinant, nonreplicating and killed vaccines, as they are substances that boost, shape, and/or enhance the immune response triggered by vaccination. Saponins obtained from the Chilean Q. saponaria tree are used as vaccine adjuvants in commercial vaccines, although they are scarce and difficult to obtain. In addition, tree felling is needed during its extraction, which has ecological impact. Q. brasiliensis leaf-extracted saponins arise as a more sustainable alternative, although its use is still limited to preclinical studies. Despite the remarkable immunostimulating properties of saponins, they are toxic to mammalian cells, due to their intrinsic characteristics. For these reasons they are mostly used in veterinary vaccines, although recently the Q. saponaria purified saponin QS-21 has been included in adjuvant systems for human vaccines, such as Mosquirix and Shingrix (GSK). In order to abrogate the toxicity of the saponins fractions, they can be formulated as immunostimulating complexes (ISCOMs). ISCOM-matrices are cage-like nanoparticles of approximately 40 nm, formulated combining saponins and lipids, without antigen, and are great adjuvants able to promote Th1-biased immune responses in a safe manner. Herein we describe how to formulate ISCOM-matrices nanoparticles using Q. brasiliensis purified saponin fractions (IMXQB) by the dialysis method. In addition, we indicate how to verify the appropriate size and homogeneity of the formulated nanoparticles.

Immunotherapeutic nanoparticles: From autoimmune disease control to the development of vaccines

The development of nanoparticles (NPs) with potential therapeutic uses represents an area of vast interest in the scientific community during the last years. Recently, the pandemic caused by COVID-19 motivated a race for vaccines creation to overcome the crisis generated. This is a good demonstration that nanotechnology will most likely be the basis of future immunotherapy. Moreover, the number of publications based on nanosystems has significantly increased in recent years and it is expected that most of these developments can go on to experimentation in clinical stages soon. The therapeutic use of NPs to combat different diseases such as cancer, allergies or autoimmune diseases will depend on their characteristics, their targets, and the transported molecules. This review presents an in-depth analysis of recent advances that have been developed in order to obtain novel nanoparticulate based tools for the treatment of allergies, autoimmune diseases and for their use in vaccines. Moreover, it is highlighted that by providing targeted delivery an increase in the potential of vaccines to induce an immune response is expected in the future. Definitively, the here gathered analysis is a good demonstration that nanotechnology will be the basis of future immunotherapy.

Caspase-1-Dependent Pyroptosis Mediates Adjuvant Activity of Platycodin D as an Adjuvant for Intramuscular Vaccines

Platycodin D (PD) is a potent adjuvant with dual Th1 and Th2 potentiating activity, but its mechanisms of action remain unclear. Here, the C2C12 myoblast cell line and mice were used as in vitro and in vivo models to identify potential signaling pathways involved in the adjuvant activity of PD. PD induced a transient cytotoxicity and inflammatory response in the C2C12 cells and in mouse quadricep muscles. A comparative analysis of microarray data revealed that PD induced similar gene expression profiles in the C2C12 cells and in the quadricep muscles, and triggered rapid regulation of death, immune, and inflammation-related genes, both in vivo and in vitro. It was further demonstrated that caspase-1-dependent pyroptosis was involved in the PD-induced cytotoxicity and inflammatory response in the C2C12 cells via the Ca²⁺–c-jun N-terminal kinase (JNK)/p38 mitogen-activated protein kinase (MAPK)–NLR family pyrin domain containing 3 (NLRP3) inflammasome signaling pathway. Consistently, the in vivo analysis revealed that a local blockage of NLRP3 and caspase-1 inhibited PD-induced cytokine production and immune cell recruitment at the injection site, and impaired the adjuvant activity of PD on antigen-specific immune responses to model antigen ovalbumin (OVA) in mice. These findings identified the caspase-1-dependent adjuvanticity of PD and expanded the current knowledge on the mechanisms of action of saponin-based adjuvants.

Tannic Acid Exhibits Adjuvant Activity by Enhancing Humoral and Cell-Mediated Immunity Against BSA as a Protein Antigen

BACKGROUND

Immunization or vaccination is the process of inducing artificial immunity against an antigen taking advantage of the mechanisms of immunological memory. Current vaccines include substances known as adjuvants, which tend to improve the immunogenicity of the antigen, reduce the antigen quantity employed, and boost the immune response in weak responders. Unfortunately, only a few vaccine adjuvants are approved for human use.

OBJECTIVE

Thus, the objective of this study was to investigate the effect of Tannic acid on humoral and cell-mediated immunity against bovine serum albumin (BSA) as a protein antigen in Wistar rats.

METHOD

In order to establish the Tannic acid concentration to test it as an adjuvant, the lethal dose 50 and maximum non-toxic dose were calculated through cytotoxicity and hemolytic assays with J774 A.1 cell line and rat erythrocytes by resazurin reduction method and UV/vis spectrophotometry. Thirty Wistar rats were divided into 5 groups that included two controls without antigen and three treatment groups of adjuvants plus BSA as a protein antigen. The rats were immunized in a 30-day scheme. Blood samples were collected for humoral immunity analysis by means of immunoglobulin quantification, isotyping and antigen-antibody precipitation inhibition analysis. Rat peritoneal macrophages and splenocytes were isolated for cell-mediated immunity analysis by means of nitric oxide quantification from adjuvant stimulated peritoneal macrophages and lymphocytes proliferation assay.

RESULTS

Tannic acid was capable of increasing the immunogenicity of the antigen; besides, it was able to stimulate cell-mediated immunity by means of increased lymphocyte proliferation. Moreover, Tannic acid improved the humoral response by means of increased specific antibodies titers. These activities may be attributed to pattern recognition receptors stimulation.

CONCLUSION

Tannic acid was considered biocompatible when tested in vivo because the concentration tested did not show cytotoxicity or hemolytic effect, and there was no detrimental effect observed on the animals' health. These results show Tannic acid as a promising candidate for vaccine adjuvant.

ISCOM-like Nanoparticles Formulated with Quillaja brasiliensis Saponins Are Promising Adjuvants for Seasonal Influenza Vaccines

Vaccination is the most effective public health intervention to prevent influenza infections, which are responsible for an important burden of respiratory illnesses and deaths each year. Currently, licensed influenza vaccines are mostly split inactivated, although in order to achieve higher efficacy rates, some influenza vaccines contain adjuvants. Although split-inactivated vaccines induce mostly humoral responses, tailoring mucosal and cellular immune responses is crucial for preventing influenza infections. Quillaja brasiliensis saponin-based adjuvants, including ISCOM-like nanoparticles formulated with the QB-90 saponin fraction (IQB90), have been studied in preclinical models for more than a decade and have been demonstrated to induce strong humoral and cellular immune responses towards several viral antigens. Herein, we demonstrate that a split-inactivated IQB90 adjuvanted influenza vaccine triggered a protective immune response, stronger than that induced by a commercial unadjuvanted vaccine, when applied either by the subcutaneous or the intranasal route. Moreover, we reveal that this novel adjuvant confers up to a ten-fold dose-sparing effect, which could be crucial for pandemic preparedness. Last but not least, we assessed the role of caspase-1/11 in the generation of the immune response triggered by the IQB90 adjuvanted influenza vaccine in a mouse model and found that the cellular-mediated immune response triggered by the IQB90-Flu relies, at least in part, on a mechanism involving the casp-1/11 pathway but not the humoral response elicited by this formulation.

Predictive and Experimental Immunogenicity of Burkholderia Collagen-like Protein 8-Derived Antigens

Burkholderia pseudomallei is an infectious bacterium of clinical and biodefense concern, and is the causative agent of melioidosis. The mortality rate can reach up to 50% and affects 165,000 people per year; however, there is currently no vaccine available. In this study, we examine the antigen-specific immune response to a vaccine formulated with antigens derived from an outer membrane protein in B. pseudomallei, Bucl8. Here, we employed a number of bioinformatic tools to predict Bucl8-derived epitopes that are non-allergenic and non-toxic, but would elicit an immune response. From these data, we formulated a vaccine based on two extracellular components of Bucl8, the β-barrel loops and extended collagen and non-collagen domains. Outbred CD-1 mice were immunized with vaccine formulations—composed of recombinant proteins or conjugated synthetic peptides with adjuvant—to assess the antigen-specific immune responses in mouse sera and lymphoid organs. We found that mice vaccinated with either Bucl8-derived components generated a robust TH2-skewed antibody response when antigen was combined with the adjuvant AddaVax, while the TH1 response was limited. Mice immunized with synthetic loop peptides had a stronger, more consistent antibody response than recombinant protein antigens, based on higher IgG titers and recognition of bacteria. We then compared peptide-based vaccines in an established C57BL/6 inbred mouse model and observed a similar TH2-skewed response. The resulting formulations will be applied in future studies examining the protection of Bucl8-derived vaccines.

Recent Advances and Applications of Plant-Based Bioactive Saponins in Colloidal Multiphase Food Systems

The naturally occurring saponins exhibit remarkable interfacial activity and also possess many biological activities linking to human health benefits, which make them particularly attractive as bifunctional building blocks for formulation of colloidal multiphase food systems. This review focuses on two commonly used food-grade saponins, Quillaja saponins (QS) and glycyrrhizic acid (GA), with the aim of clarifying the relationship between the structural features of saponin molecules and their subsequent self-assembly and interfacial properties. The recent applications of these two saponins in various colloidal multiphase systems, including liquid emulsions, gel emulsions, aqueous foams and complex emulsion foams, are then discussed. A particular emphasis is on the unique use of GA and GA nanofibrils as sole stabilizers for fabricating various multiphase food systems with many advanced qualities including simplicity, ultrastability, stimulability, structural viscoelasticity and processability. These natural saponin and saponin-based colloids are expected to be used as sustainable, plant-based ingredients for designing future foods, cosmetics and pharmaceuticals.

Vaccine Composition Formulated with a Novel Lactobacillus-Derived Exopolysaccharides Adjuvant Provided High Protection against Staphylococcus aureus

A vaccine that effectively targets methicillin-resistant Staphylococcus aureus (MRSA) is urgently needed, and has been the focus of studies by numerous research groups, but with limited success to date. Recently, our team found that exopolysaccharides derived from probiotic Lactobacilluscasei strain WXD030 as an adjuvant-formulated OVA could upregulate IFN-γ and IL-17 expression in CD4⁺ T cells. In this study, we developed a vaccine (termed rMntC-EPS) composed of S. aureus antigen MntC and Lactobacillus casei exopolysaccharides, which conferred high levels of protection against S. aureus infection. Methods: Six–eight-week-old female mice were vaccinated with purified rMntC-EPS30. The immune protection function of rMntC-EPS30 was assessed by the protective effect of rMntC-EPS30 to S. aureus-induced pulmonary and cutaneous infection in mice, bacterial loads and H&E in injury site, and ELISA for inflammation-related cytokines. The protective mechanism of rMntC-EPS30 was assessed by ELISA for IgG in serum, cytokines in the spleen and lungs of vaccinated mice. In addition, flow cytometry was used for analyzing cellular immune response induced by rMntC-EPS30. For confirmation of our findings, three kinds of mice were used in this study: IL-17A knockout mice, IFN-γ knockout mice and TCRγ/δ knockout mice. Results: rMntC-EPS30 conferred up to 90% protection against S. aureus pulmonary infection and significantly reduced the abscess size in the S. aureus cutaneous model, with clearance of the pathogen. The rMntC-EPS vaccine could induce superior humoral immunity as well as significantly increase IL-17A and IFN-γ production. In addition, we found that rMntC-EPS vaccination induced robust Th 17/γδ T 17 primary and recall responses. Interestingly, this protective effect was distinctly reduced in the IL-17A knockout mice but not in IFN-γ knockout mice. Moreover, in TCRγ/δ knockout mice, rMntC-EPS vaccination neither increased IL-17A secretion nor provided effective protection against S. aureus infection. Conclusions: These data demonstrated that the rMntC formulated with a novel Lactobacillus-derived Exopolysaccharides adjuvant provided high protection against Staphylococcus aureus. The rMntC-EPS vaccine induced γδ T cells and IL-17A might play substantial roles in anti-S. aureus immunity. Our findings provided direct evidence that rMntC-EPS vaccine is a promising candidate for future clinical application against S. aureus-induced pulmonary and cutaneous infection.

Carbohydrate-containing nanoparticles as vaccine adjuvants

Introduction: Adjuvants are essential to vaccines for immunopotentiation in the elicitation of protective immunity. However, classical and widely used aluminum-based adjuvants have limited capacity to induce cellular response. There are increasing needs for appropriate adjuvants with improved profiles for vaccine development toward emerging pathogens. Carbohydrate-containing nanoparticles (NPs) with immunomodulatory activity and particulate nanocarriers for effective antigen presentation are capable of eliciting a more balanced humoral and cellular immune response.Areas covered: We reviewed several carbohydrates with immunomodulatory properties. They include chitosan, β-glucan, mannan, and saponins, which have been used in vaccine formulations. The mode of action, the preparation methods, characterization of these carbohydrate-containing NPs and the corresponding vaccines are presented.Expert opinion: Several carbohydrate-containing NPs have entered the clinical stage or have been used in licensed vaccines for human use. Saponin-containing NPs are being evaluated in a vaccine against SARS-CoV-2, the pathogen causing the on-going worldwide pandemic. Vaccines with carbohydrate-containing NPs are in different stages of development, from preclinical studies to late-stage clinical trials. A better understanding of the mode of action for carbohydrate-containing NPs as vaccine carriers and as immunostimulators will likely contribute to the design and development of new generation vaccines against cancer and infectious diseases.

Potential therapeutic applications of phytoconstituents as immunomodulators: Pre-clinical and clinical evidences

Autoimmune and infectious diseases are the major public health issues and have gained great attention in the last few years for the search of new agents with therapeutic benefits on the host immune functions. In recent years, natural products (NPs) have been studied broadly for their multi-targeted activities under pathological conditions. Interestingly, several attempts have been made to outline the immunomodulatory properties of NPs. Research on in-vitro and in-vivo models have shown the immunomodulatory activity of NPs, is due to their antiinflammatory property, induction of phagocytosis and immune cells stimulation activity. Moreover, studies on humans have suggested that phytomedicines reduce inflammation and could provide appropriate benefits either in single form or complex combinations with other agents preventing disease progression, subsequently enhancing the efficacy of treatment to combat multiple malignancies. However, the exact mechanism of immunomodulation is far from clear, warranting more detailed investigations on their effectiveness. Nevertheless, the reduction of inflammatory cascades is considered as a prime protective mechanism in a number of inflammation regulated autoimmune diseases. Altogether, this review will discuss the biological activities of plant-derived secondary metabolites, such as polyphenols, alkaloids, saponins, polysaccharides and so forth, against various diseases and their potential use as an immunomodulatory agent under pathological conditions.

Zika Virus Envelope Domain III Recombinant Protein Delivered With Saponin-Based Nanoadjuvant From Quillaja brasiliensis Enhances Anti-Zika Immune Responses, Including Neutralizing Antibodies and Splenocyte Proliferation

Nanoadjuvants that combine immunostimulatory properties and delivery systems reportedly bestow major improvements on the efficacy of recombinant, protein-based vaccines. Among these, self-assembled micellar formulations named ISCOMs (immune stimulating complexes) show a great ability to trigger powerful immunological responses against infectious pathogens. Here, a nanoadjuvant preparation, based on saponins from Quillaja brasiliensis, was evaluated together with an experimental Zika virus (ZIKV) vaccine (IQB80-zEDIII) and compared to an equivalent vaccine with alum as the standard adjuvant. The preparations were administered to mice in two doses (on days zero and 14) and immune responses were evaluated on day 28 post-priming. Serum levels of anti-Zika virus IgG, IgG1, IgG2b, IgG2c, IgG3 were significantly increased by the nanoadjuvant vaccine, compared to the mice that received the alum-adjuvanted vaccine or the unadjuvanted vaccine. In addition, a robust production of neutralizing antibodies and in vitro splenocyte proliferative responses were observed in mice immunized with IQB80-zEDIII nanoformulated vaccine. Therefore, the IQB80-zEDIII recombinant preparation seems to be a suitable candidate vaccine for ZIKV. Overall, this study identified saponin-based delivery systems as an adequate adjuvant for recombinant ZIKV vaccines and has important implications for recombinant protein-based vaccine formulations against other flaviviruses and possibly enveloped viruses.

cGAMP/Saponin Adjuvant Combination Improves Protective Response to Influenza Vaccination by Microneedle Patch in an Aged Mouse Model

Current strategies for improving protective response to influenza vaccines during immunosenescence do not adequately protect individuals over 65 years of age. Here, we used an aged mouse model to investigate the potential of co-delivery of influenza vaccine with the recently identified combination of a saponin adjuvant Quil-A and an activator of the STING pathway, 2’3 cyclic guanosine monophosphate–adenosine monophosphate (cGAMP) via dissolving microneedle patches (MNPs) applied to skin. We demonstrate that synergy between the two adjuvant components is observed after their incorporation with H1N1 vaccine into MNPs as revealed by analysis of the immune responses in adult mice. Aged 21-month-old mice were found to be completely protected against live influenza challenge after vaccination with the MNPs adjuvanted with the Quil-A/cGAMP combination (5 µg each) and demonstrated significantly reduced morbidity compared to the observed responses in these mice vaccinated with unadjuvanted MNPs. Analysis of the lung lysates of the surviving aged mice post challenge revealed the lowest level of residual inflammation in the adjuvanted groups. We conclude that combining influenza vaccine with a STING pathway activator and saponin-based adjuvant in MNPs is a novel option for skin vaccination of the immunosenescent population, which is at high risk for influenza.

The Possible Role of Saponin in Type-II Diabetes- A Review

BACKGROUND

The possible role of secondary metabolites in the management of diabetes is a great concern and constant discussion. This characteristic seems relevant and should be the subject of thorough discussion with respect to saponin.

OBJECTIVE

The current data mainly focus on the impact of saponin in the treatment of type-II diabetes. The majority of studies emphasize on other secondary metabolites such as alkaloids and flavonoids, but very few papers are there representing the possible role of saponin as these papers express the narrow perspective of saponin phytoconstituents but lacking in providing the complete information on various saponin plants. The aim of the study was to summarize all available data concerning the saponin containing plant in the management of type-II diabetes.

METHODS

All relevant papers on saponin were selected. This review summarizes the saponin isolation method, mechanism of action, clinical significance, medicinal plants and phytoconstituents responsible for producing a therapeutic effect in the management of diabetes.

RESULTS

The saponin is of high potential with structural diversity and inhibits diabetic complications along with reducing the hyperglycemia through different mechanisms thereby providing scope for improving the existing therapy and developing the novel medicinal agents for curing diabetes.

CONCLUSION

Saponins having potential therapeutic benefits and are theorized as an alternative medication in decreasing serum blood glucose levels in the patient suffering from diabetes.

IMXQB-80: A Quillaja brasiliensis saponin-based nanoadjuvant enhances Zika virus specific immune responses in mice

Vaccine adjuvants are compounds that enhance/prolong the immune response to a co-administered antigen. Saponins have been widely used as adjuvants for many years in several vaccines - especially for intracellular pathogens - including the recent and somewhat revolutionary malaria and shingles vaccines. In view of the immunoadjuvant potential of Q. brasiliensis saponins, the present study aimed to characterize the QB-80 saponin-rich fraction and a nanoadjuvant prepared with QB-80 and lipids (IMXQB-80). In addition, the performance of such adjuvants was examined in experimental inactivated vaccines against Zika virus (ZIKV). Analysis of QB-80 by DI-ESI-ToF by negative ion electrospray revealed over 29 saponins that could be assigned to known structures existing in their congener Q. saponaria, including the well-studied QS-21 and QS-7. The QB-80 saponins were a micrOTOF able to self-assembly with lipids in ISCOM-like nanoparticles with diameters of approximately 43 nm, here named IMXQB-80. Toxicity assays revealed that QB-80 saponins did present some haemolytical and cytotoxic potentials; however, these were abrogated in IMXQB-80 nanoparticles. Regarding the adjuvant activity, QB-80 and IMXQB-80 significantly enhanced serum levels of anti-Zika virus IgG and subtypes (IgG1, IgG2b, IgG2c) as well as neutralized antibodies when compared to an unadjuvanted vaccine. Furthermore, the nanoadjuvant IMXQB-80 was as effective as QB-80 in stimulating immune responses, yet requiring fourfold less saponins to induce the equivalent stimuli, and with less toxicity. These findings reveal that the saponin fraction QB-80, and particularly the IMXQB-80 nanoadjuvant, are safe and capable of potentializing immune responses when used as adjuvants in experimental ZIKV vaccines.

Inflammasome-Mediated Immunogenicity of Clinical and Experimental Vaccine Adjuvants

In modern vaccines, adjuvants can be sophisticated immunological tools to promote robust and long-lasting protection against prevalent diseases. However, there is an urgent need to improve immunogenicity of vaccines in order to protect mankind from life-threatening diseases such as AIDS, malaria or, most recently, COVID-19. Therefore, it is important to understand the cellular and molecular mechanisms of action of vaccine adjuvants, which generally trigger the innate immune system to enhance signal transition to adaptive immunity, resulting in pathogen-specific protection. Thus, improved understanding of vaccine adjuvant mechanisms may aid in the design of “intelligent” vaccines to provide robust protection from pathogens. Various commonly used clinical adjuvants, such as aluminium salts, saponins or emulsions, have been identified as activators of inflammasomes - multiprotein signalling platforms that drive activation of inflammatory caspases, resulting in secretion of pro-inflammatory cytokines of the IL-1 family. Importantly, these cytokines affect the cellular and humoral arms of adaptive immunity, which indicates that inflammasomes represent a valuable target of vaccine adjuvants. In this review, we highlight the impact of different inflammasomes on vaccine adjuvant-induced immune responses regarding their mechanisms and immunogenicity. In this context, we focus on clinically relevant adjuvants that have been shown to activate the NLRP3 inflammasome and also present various experimental adjuvants that activate the NLRP3-, NLRC4-, AIM2-, pyrin-, or non-canonical inflammasomes and could have the potential to improve future vaccines. Together, we provide a comprehensive overview on vaccine adjuvants that are known, or suggested, to promote immunogenicity through inflammasome-mediated signalling.

Enhancement in humoral response against inactivated Newcastle disease vaccine in broiler chickens administered orally with plant-derived soyasaponin

The present study aimed to evaluate the immunopotentiating effect of plant-derived soyasaponin and its immunogenicity in chickens challenged with Newcastle disease virus (NDV). Soyasaponin was extracted from soybean seeds and detected using the phytochemical tests, followed by quantification through the dry-weight method. One-day-old broiler chicks (n = 90) were divided into 3 groups, named as A, B, and C. Group A birds were orally administrated with soyasaponin (5 mg/kg), followed by immunization with inactivated ND vaccine intramuscularly (IM), whereas group B birds were vaccinated with inactivated ND vaccine alone. Group C birds were kept unvaccinated. A booster dose on day 21 was also administered IM to group A and B birds. At day 35, all 3 groups were challenged with NDV. To determine the immunogenicity potential of soyasaponin, antibody titer was measured using the hemagglutination inhibition test before and after the NDV challenge. Histochemical examination was performed to determine the pathological changes associated with NDV infection. Foam formation and hemolytic activity confirmed the presence of saponin in soya bean extract. Group A birds showed a higher antibody response compared with group B and C birds. The disease challenge study showed that soyasaponin-adjuvanted NDV vaccine provided complete protection to group A birds against ND. Moreover, no side effects of soyasaponin were observed on the growth performance of birds during the experiment. Therefore, we can conclude that soyasaponin is a potential immunogenic agent and therefore could be a promising candidate to launch a protective humoral response against ND in chickens.

Pathogen Molecular Pattern Receptor Agonists: Treating Cancer by Mimicking Infection

Immunotherapies such as checkpoint blockade have achieved durable benefits for patients with advanced stage cancer and have changed treatment paradigms. However, these therapies rely on a patient's own a priori primed tumor-specific T cells, limiting their efficacy to a subset of patients. Because checkpoint blockade is most effective in patients with inflamed or "hot" tumors, a priority in the field is learning how to "turn cold tumors hot." Inflammation is generally initiated by innate immune cells, which receive signals through pattern recognition receptors (PRR)-a diverse family of receptors that sense conserved molecular patterns on pathogens, alarming the immune system of an invading microbe. Their immunostimulatory properties can reprogram the immune suppressive tumor microenvironment and activate antigen-presenting cells to present tumors antigens, driving de novo tumor-specific T-cell responses. These features, among others, make PRR-targeting therapies an attractive strategy in immuno-oncology. Here, we discuss mechanisms of PRR activation, highlighting ongoing clinical trials and recent preclinical advances focused on therapeutically targeting PRRs to treat cancer.

Foamy matters: an update on Quillaja saponins and their use as immunoadjuvants

Immunoadjuvant Quillaja spp. tree saponins stimulate both cellular and humoral responses, significantly widening vaccine target pathogen spectra. Host toxicity of specific saponins, fractions and extracts may be rather low and further reduced using lipid-based delivery systems. Saponins contain a hydrophobic central aglycone decorated with several sugar residues, posing a challenge for viable chemical synthesis. These, however, may provide simpler analogs. Saponin chemistry affords characteristic interactions with cell membranes, which are essential for its mechanism of action. Natural sources include Quillaja saponaria barks and, more recently, Quillaja brasiliensis leaves. Sustainable large-scale supply can use young plants grown in clonal gardens and elicitation treatments. Quillaja genomic studies will most likely buttress future synthetic biology-based saponin production efforts.

Saponins from Quillaja saponaria and Quillaja brasiliensis: Particular Chemical Characteristics and Biological Activities

Quillaja saponaria Molina represents the main source of saponins for industrial applications. Q. saponaria triterpenoids have been studied for more than four decades and their relevance is due to their biological activities, especially as a vaccine adjuvant and immunostimulant, which have led to important research in the field of vaccine development. These saponins, alone or incorporated into immunostimulating complexes (ISCOMs), are able to modulate immunity by increasing antigen uptake, stimulating cytotoxic T lymphocyte production (Th1) and cytokines (Th2) in response to different antigens. Furthermore, antiviral, antifungal, antibacterial, antiparasitic, and antitumor activities are also reported as important biological properties of Quillaja triterpenoids. Recently, other saponins from Q. brasiliensis (A. St.-Hill. & Tul.) Mart. were successfully tested and showed similar chemical and biological properties to those of Q. saponaria barks. The aim of this manuscript is to summarize the current advances in phytochemical and pharmacological knowledge of saponins from Quillaja plants, including the particular chemical characteristics of these triterpenoids. The potential applications of Quillaja saponins to stimulate further drug discovery research will be provided.