A new vaccine adjuvant (BOS 2000) a potent enhancer mixed Th1/Th2 immune responses in mice immunized with HBsAg

Plant-derived bioactive compounds as key players in the modulation of immune-related conditions

The immune system is a complex and fundamental network for organism protection. A minimal unbalance in the host defense system homeostasis can originate severe repercussions in human health. Fundamentally, immune-related diseases can arise from its compromise (immunodeficiency diseases), overactivation against itself (autoimmune diseases) or harmless substances (allergies), and failure of eliminating the harmful agent (chronic inflammation). The notable advances and achievements in the immune system diseases pathophysiology have been allowing for a dramatic improvement of the available treatments. Nevertheless, they present some drawbacks, including the inappropriate benefit/risk ratio. Therefore, there is a strong and urgent need to develop effective therapeutic strategies. Nature is a valuable source of bioactive compounds that can be explored for the development of new drugs. Particularly, plants produce a broad spectrum of secondary metabolites that can be potential prototypes for innovative therapeutic agents. This review describes the immune system and the inflammatory response and examines the current knowledge of eight plants traditionally used as immunomodulatory medicines (Boswellia serrata, Echinacea purpurea, Laurus nobilis, Lavandula angustifolia, Olea europaea, Salvia officinalis, Salvia rosmarinus, and Taraxacum officinale). Moreover, the issues responsible for possible biologic readout inconsistencies (plant species, age, selected organ, developmental stage, growth conditions, geographical location, drying methods, storage conditions, solvent of extraction, and extraction method) will also be discussed. Furthermore, a detailed list of the chemical composition and the immunomodulatory mechanism of action of the bioactive compounds of the selected plant extracts are presented. This review also includes future perspectives and proposes potential new avenues for further investigation.

Immunostimulant plant proteins: Potential candidates as vaccine adjuvants

The COVID-19 pandemic is shaking up global scientific structures toward addressing antibiotic resistance threats and indicates an urgent need to develop more cost-effective vaccines. Vaccine adjuvants play a crucial role in boosting immunogenicity and improving vaccine efficacy. The toxicity and adversity of most adjuvant formulations are the major human immunization problems, especially in routine pediatric and immunocompromised patients. The present review focused on preclinical studies of immunoadjuvant plant proteins in use with antiparasitic, antifungal, and antiviral vaccines. Moreover, this report outlines the current perspective of immunostimulant plant protein candidates that can be used by researchers in developing new generations of vaccine-adjuvants. Future clinical studies are required to substantiate the plant proteins' safety and applicability as a vaccine adjuvant in pharmaceutical manufacturing.

Supplementation with a new food grade delivery system of Boswellia and Centella in the intervertebral discs registry: the Sager study

BACKGROUND

The aim of this registry study was to investigate the potential of a new food-grade formulation of the association of Boswellia serrata and Centella asiatica extracts (Boswellia/Centella Phytosome, [BCP]) in combination with standard management (SM) to produce a faster re-expansion of the intervertebral disks in symptomatic subjects with "flattened" disks in the lower spine, due to wrong posture and compression after repeated trauma.

METHODS

The study was designed as a 3-6 months pilot registry. Three groups of subjects were comparable for characteristics and symptoms at baseline: SM+BCP; SM; SM+glucosamine.

RESULTS

No side effects were observed. Regarding target measurements at 3 and 6 months, height increased in the BCP group vs. the other two groups. The total spine length improved in the BCP group (P<0.05); in particular at 6 months the increase was doubled with BCP. SM was effective in producing elongation but the association with BCP made spinal elongation faster, more effective, with a better expansion of the intervertebral disks. Regarding ultrasound measurements, BCP was able to significantly ameliorate the posterior disk space (P<0.05) and decreased disk density more than the other groups of the study. Signs/symptoms and mobility were improved with BCP (P<0.05), while rescue medications decreased. The loss of working days was reduced with all managements (significantly more in BCP group than in the other two).

CONCLUSIONS

The relative effects on spinal elongation, disk space, signs/symptoms of BCP appeared to double the efficacy of SM, improving symptoms associated to a very good tolerability of BCP.

Standardized Plant Extract Alleviates the Negative Effects of FMD Vaccination on Animal Performance

Simple Summary

Foot and Mouth Disease (FMD) is among the viral diseases causing poor growth performance and reduced immune status, leading to heavy economic losses in livestock. The vaccination of animals against FMD may lead to vaccination stress, thereby reducing the growth performance of animals. The growth promoting effects of a plant extract (consisting of capsicum and turmeric oleoresins) against FMD vaccinated growing pigs are evaluated in the present study. It was determined that the supplementation of the plant extract significantly improved performance and increased the antibody titer against FMD antigens. However, the immune parameters measured at days 10, 15, 20 and 25 post-FMD vaccination remained unaffected.

Abstract

The present study was conducted to assess the efficacy of a plant extract (PE) on growth performance and immune status in foot and mouth disease (FMD)-vaccinated growing pigs. A total of 120 crossed ((Landrace × Yorkshire) × Duroc) growing pigs with an average initial body weight (BW) of 24.66 ± 2.34 kg and an average age of 70 days were randomized into three groups (10 pens; 4 pigs per pen per treatment) as follows: a nonvaccinated negative control group (NV), a FMD vaccinated group (OV), and a third group received a 0.0125% PE supplement after vaccination (PV), in a 6-week trial. The PV group receiving PE supplementation increased (p < 0.05) the BW compared with the OV group, and average daily gain (ADG) during days 1–14, overall and gain-to-feed ratio (G: F) in days 1–14, and dry matter (DM) digestibility at week 6 were higher (p < 0.05) in the PV compared with the OV group. A significant increase (p < 0.05) in haptoglobin concentration was observed in the OV group compared with the NV group at 25 days postvaccination. The inhibition percentage of antibodies against FMD in the sera reached above 50% in the PV group 5 days earlier than in the OV group. The findings suggest that the inclusion of PE in the diet promoted the performance of vaccinated growing pigs.

Acute exposure and chronic retention of aluminum in three vaccine schedules and effects of genetic and environmental variation

Like the mechanisms of action as adjuvants, the pharmacodynamics of injected forms of aluminum commonly used in vaccines are not well-characterized, particularly with respect to how differences in schedules impact accumulation and how factors such as genetics and environmental influences on detoxification influence clearance. Previous modeling efforts are based on very little empirical data, with the model by Priest based on whole-body clearance rates estimated from a study involving a single human subject. In this analysis, we explore the expected acute exposures and longer-term whole-body accumulation/clearance across three vaccination schedules: the current US Centers for Disease Control and Prevention (CDC) schedule, the current CDC schedule using low aluminum or no aluminum vaccines, and Dr. Paul Thomas' "Vaccine Friendly Plan" schedule. We then study the effects of an implicit assumption of the Priest model on whether clearance dynamics from successive doses are influenced by the current level of aluminum or modeled by the assumption that a new dose has its own whole-body dynamics "reset" on the day of injection. We model two additional factors: variation (deficiency) in aluminum detoxification, and a factor added to the Priest equation to model the potential impact of aluminum itself on cellular and whole-body detoxification. These explorations are compared to a previously estimated pediatric dose limit (PDL) of whole-body aluminum exposure and provide a new statistic: %alumTox, the (expected) percentage of days (or weeks) an infant is in aluminum toxicity, reflecting chronic toxicity. We show that among three schedules, the CDC schedule results in the highest %alumTox regardless of model assumptions, and the Vaccine Friendly Plan schedule, which avoids >1 ACV per office visit results in the lowest (expected) %alumTox. These results are conservative, as the MSL is derived from data used by FDA to estimate safety of aluminum in adult humans. These results demonstrate high potential utility of modeling variation in patient responses to aluminum. More empirical data from individuals who are suspected of being intolerant of aluminum from vaccines, evidenced by high aluminum retention, neurodevelopmental disorders and/or a myriad of chronic illnesses would help answer questions on whether the model predictions can be used to estimate parameter values tied to genetic factors including genomic sequence variation and family history of chronic illnesses tied to aluminum exposure.

Novel trisaccharide based phospholipids as immunomodulators

A focused library of novel mannosylated glycophospholipids was synthesized employing imidate coupling and H-phosphate phosphorylation methods. All novel glycophospholipids were evaluated for their receptor interactions by molecular docking studies. Docking studies revealed dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) specific interaction of the glycophospholipid ligand P4 acts, which was further confirmed by in vitro DC-SIGN expression on monocyte-derived dendritic cells (MoDCs). Further, in vitro and in vivo immunomodulatory activity among the six compounds (P1-P6) examined, compound P4 displayed good immunopotentiation and adjuvant properties as indicated by the induced cytokine expression and enhanced ovalbumin (OVA) specific antibody (IgG) titers. Phosphatidylinositol mannosides (PIMs) analogues in the present study enforced the immunomodulatory properties, truncating parent PIMs or tailor-made of PIMs may bring the novel efficacious molecules, which will be useful in vaccine preparation against different diseases.

Isolation, structure elucidation, and immunostimulatory activity of polysaccharide fractions from Boswellia carterii frankincense resin

Frankincense has a long history in religious, cultural, and medicinal use. In this study polysaccharides were extracted from frankincense from Boswellia carterii. The polysaccharides were purified by anion exchange chromatography on a DEAE-Sepharose Fast Flow 16/10 FPLC column. Six fractions were obtained and the three most active immunomodulatory fractions were further purified by size exclusion chromatography on a Superdex-200 column. The composition showed the monosaccharides present were predominantly galactose, arabinose, and glucuronic acid along with small amounts of rhamnose and glucose. The monosaccharide composition and glycosyl linkage analysis revealed the polysaccharides belong to the type II arabinogalactans. Fourier-transform infrared spectroscopy and bicinchoninic acid assay showed that the amount of protein in the samples was <1 wt%. One-dimensional ¹H NMR were consistent with high molecular weight compounds. The monosaccharides were primarily in the β conformation. The three fractions exhibited an immunostimulatory effect on RAW 264.7 murine macrophage cells. The most active immunostimulatory fraction FA2, stimulated a range of pro-inflammatory mediators including iNOS, NO, TNF-α, and IL-6 in RAW 264.7 cells. The fractions were effective in proliferating primary murine splenocytes. The results indicate that the polysaccharides isolated from frankincense have the potential to be used as an immunological stimulant or nutraceutical.

Potential Hepatitis B Vaccine Formulation Prepared by Uniform-Sized Lipid Hybrid PLA Microparticles with Adsorbed Hepatitis B Surface Antigen

For the purpose of strengthening the immunogenicity of the hepatitis B vaccine, which contains hepatitis B surface antigen (HBsAg), the development of biodegradable poly(lactic acid) (PLA) microparticles (MPs) modified with the cationic surfactant didodecyldimethylammonium bromide (DDAB) was attempted. DDAB-PLA MPs with an uniform size of about 1 μm were prepared in a simple and mild way. DDAB-PLA MPs with increased surface charge enhanced antigen adsorption capacity compared to plain PLA MPs. After immunization, DDAB-PLA MPs induced the gene expression of inflammatory cytokines and chemokines, which facilitated the following immune responses. DDAB-PLA MPs augmented the expression of co-stimulatory molecules along with the activation of bone-marrow-derived dendritic cells (BMDCs). DDAB-PLA MP-based vaccine formulations efficiently induced antibody production more than the aluminum-based vaccine and plain PLA MP-based formulation in vivo. Moreover, DDAB-PLA MPs were more likely to generate the polarization of the Th1 response indicating the cytotoxic ability against infectious pathogens. In conclusion, DDAB-PLA MPs could be a potent vaccine formulation to prime robust cellular and humoral immune responses.

Lipid A adjuvanted Chylomicron Mimicking Solid Fat Nanoemulsions for Immunization Against Hepatitis B

Traditional parenteral recombinant hepatitis B virus (HBV) vaccines have effectively reduced the disease burden despite being able to induce seroprotective antibody titers in 5-10% vaccinated individuals (non-responders). Moreover, an estimated 340 million chronic HBV cases are in need of treatment. Development of safe, stable, and more effective hepatitis B vaccine formulation would address these challenges. Recombinant hepatitis B surface antigen (rHBsAg) entrapped solid fat nanoemulsions (SFNs) containing monophosphoryl lipid A (MPLA) that was prepared and optimized by quality by design (QbD) using response surface methodology (RSM), i.e., central composite design (CCD). Its immune potential was evaluated with preset immunization protocol in a murine model. Dose escalation study revealed that formulation containing 1 μg of rHBsAg entrapped SFNs with MPLA-induced significant higher humoral, and cellular response compared to the marketed vaccine (Genvac B) administered intramuscularly. SFNs with nanometric morphology and structural similarity with chylomicrons assist in improved uptake and processing to lymphatics. Moreover, the presence of an immunogenic component in its structure further augments delivery of rHBsAg to immune cells with induction of danger signals. This multi-adjuvant based approach explores new prospect for the dose sparing. Improved cellular immune response induced by this vaccine formulation suggests that it could be tested as an immunotherapeutic vaccine as well.

Facile fabrication of varisized calcium carbonate microspheres as vaccine adjuvants

HBsAg loaded CaCO₃ microspheres with various diameters were fabricated via different mixing strategies and 1 μm particles has the strongest immune responses as vaccine adjuvant.

Development of novel plant-based adjuvant formulation against rubella and hepatitis B vaccine antigen

Introduction: Numerous metabolites present in the aqueous extract from plants are responsible for inducing adjuvant activity against rubella and hepatitis B vaccine antigen (HBsAg). One of the medicinal plants, Adhatoda vasica has been pointed out with great potential of vaccine adjuvant property.

Objective: The objective of our study is to evaluate the adjuvant potential of aqueous leaves extract of Adhatoda vasica against rubella and hepatitis B vaccine antigen (HBsAg).

Methods: For these studies, our group evaluated the antibody (IgG) titre of HBsAg and rubella vaccine antigen using variable doses (0.625–5 mg) of aqueous leaves extract of Adhatoda vasica and also determined the lymphocyte (splenocyte) proliferation assay (0.625–5 mg; 50 μl) in mice model studies ex vivo (i.e. immunized with HBsAg subcutaneously).

Results: The results showed that aqueous leaves extract showed anti-HBsAg and anti-rubella titre and also enhanced the lymphocyte proliferation assay at higher doses (5 mg) as compared to control.

Conclusion: Aqueous leaves extract of Adhatoda vasica showed adjuvant activity against HBsAg and rubella vaccine antigen.

Efficacy evaluation of two synthetic lysine lipidated tripeptides as vaccine adjuvants against HBsAg

In the present investigation, adjuvant potential of two novel lipidated tripeptide lysine derivatives (KKSM and KKSMB) was evaluated using various in vitro and animal-derived models of humoral and cell-mediated immune events in response to hepatitis B surface antigen (HBsAg). The results were compared with alum adjuvanted with HBsAg. Both these molecules were found to stimulate anti-HBsAg IgG and neutralizing (IgG1 and IgG2a) antibody titres in mice sera. The two molecules stimulated the proliferation of T-lymphocyte sub-sets (CD4/CD8) as well as the production of soluble mediators of Th1 (IL-2 and IFN-γ) and Th2 response (IL-4) in spleen cell culture supernatant. Furthermore, the two lipidated tripeptides enhanced the CD4, CD8, CD3 and CD19 cell populations as well as CD4/CD8 derived IL-2, IL-4, IFN-γ and TNF-α in whole blood of treated mice. There was found to be the significant enhancement in the release of IL-12, IFN-γ and nitrite content in macrophage supernatant. Moreover, the two lipidated tripeptides enhanced the population of CD80 and CD86 in spleen-derived macrophages and did not show any hemolytic effect on rabbit RBCs. Taken together, these results suggest that both these molecules are the potent enhancers of anti-HBsAg immune response via augmenting Th1/Th2 response in a dose dependent manner.

Electroporation of a multivalent DNA vaccine cocktail elicits a protective immune response against anthrax and plague

Electroporation of DNA vaccines represents a platform technology well positioned for the development of multivalent biodefense vaccines. To evaluate this hypothesis, three vaccine constructs were produced using codon-optimized genes encoding Bacillus anthracis Protective Antigen (PA), and the Yersinia pestis genes LcrV and F1, cloned into pVAX1. A/J mice were immunized on a prime-boost schedule with these constructs using the electroporation-based TriGrid Delivery System. Immunization with the individual pDNA vaccines elicited higher levels of antigen-specific IgG than when used in combination. DNA vaccine effectiveness was proven, the pVAX-PA titers were toxin neutralizing and fully protective against a lethal B. anthracis spore challenge when administered alone or co-formulated with the plague pDNA vaccines. LcrV and F1 pVAX vaccines against plague were synergistic, resulting in 100% survival, but less protective individually and when co-formulated with pVAX-PA. These DNA vaccine responses were Th1/Th2 balanced with high levels of IFN-γ and IL-4 in splenocyte recall assays, contrary to complimentary protein Alum vaccinations displaying a Th2 bias with increased IL-4 and low levels of IFN-γ. These results demonstrate the feasibility of electroporation to deliver and maintain the overall efficacy of an anthrax-plague DNA vaccine cocktail whose individual components have qualitative immunological differences when combined.

Anti-arthritic activity of agnuside mediated through the down-regulation of inflammatory mediators and cytokines

OBJECTIVE AND DESIGN

The purpose of this study was to elucidate the probable mechanism for the anti-arthritic activity of agnuside (AGN), a compound isolated from the leaf extract of Vitex negundo.

METHODOLOGY

The anti-inflammatory activity of AGN within a dose range of 1.56-12.50 mg/kg in normal and adrenalectomized rats was evaluated against different inflammagens. An array of pro-inflammatory mediators (PGE(2) and LTB(4)) and T-cell-mediated cytokines (IL-2, TNF-α, IFN-γ, IL-4, IL-10, IL-17) was assayed using flow cytometry, in arthritic paw tissue homogenate and splenocytes of treated animals.

RESULTS

Significant anti-arthritic activity was observed in the polyarthritis test in rats and this was associated with significant suppression of inflammatory mediators and T-cell-mediated cytokines (Th1/Th2). The anti-inflammatory activity in adrenalectomized rats confirmed that the effect of AGN is not mediated by the pituitary-adrenal axis. AGN also showed inhibition of vascular permeability and leukocyte migration in vivo.

CONCLUSION

The study suggests the possible development of AGN as a therapeutic agent in the treatment of arthritis by the modulation of the host immune response.

Boswellia serrata: an overall assessment of in vitro, preclinical, pharmacokinetic and clinical data

Non-steroidal anti-inflammatory drug (NSAID) intake is associated with high prevalence of gastrointestinal or cardiovascular adverse effects. All efforts to develop NSAIDs that spare the gastrointestinal tract and the cardiovasculature are still far from achieving a breakthrough. In the last two decades, preparations of the gum resin of Boswellia serrata (a traditional ayurvedic medicine) and of other Boswellia species have experienced increasing popularity in Western countries. Animal studies and pilot clinical trials support the potential of B. serrata gum resin extract (BSE) for the treatment of a variety of inflammatory diseases like inflammatory bowel disease, rheumatoid arthritis, osteoarthritis and asthma. Moreover, in 2002 the European Medicines Agency classified BSE as an 'orphan drug' for the treatment of peritumoral brain oedema. Compared to NSAIDs, it is expected that the administration of BSE is associated with better tolerability, which needs to be confirmed in further clinical trials. Until recently, the pharmacological effects of BSE were mainly attributed to suppression of leukotriene formation via inhibition of 5-lipoxygenase (5-LO) by two boswellic acids, 11-keto-β-boswellic acid (KBA) and acetyl-11-keto-β-boswellic acid (AKBA). These two boswellic acids have also been chosen in the monograph of Indian frankincense in European Pharmacopoiea 6.0 as markers to ensure the quality of the air-dried gum resin exudate of B. serrata. Furthermore, several dietary supplements advertise the enriched content of KBA and AKBA. However, boswellic acids failed to inhibit leukotriene formation in human whole blood, and pharmacokinetic data revealed very low concentrations of AKBA and KBA in plasma, being far below the effective concentrations for bioactivity in vitro. Moreover, permeability studies suggest poor absorption of AKBA following oral administration. In view of these results, the previously assumed mode of action - that is, 5-LO inhibition - is questionable. On the other hand, 100-fold higher plasma concentrations have been determined for β-boswellic acid, which inhibits microsomal prostaglandin E synthase-1 and the serine protease cathepsin G. Thus, these two enzymes might be reasonable molecular targets related to the anti-inflammatory properties of BSE. In view of the results of clinical trials and the experimental data from in vitro studies of BSE, and the available pharmacokinetic and metabolic data on boswellic acids, this review presents different perspectives and gives a differentiated insight into the possible mechanisms of action of BSE in humans. It underlines BSE as a promising alternative to NSAIDs, which warrants investigation in further pharmacological studies and clinical trials.

A novel liposomal vaccine improves humoral immunity and prevents tumor pulmonary metastasis in mice

Basic fibroblast growth factor (bFGF) is an important stimulator of angiogenesis involving in neovascularization progression. The aim of this study is to evaluate whether a liposomal vaccine (MLB) based on xenogeneic human bFGF plus monophosphoryl lipid A (MPLA) could effectively induce cross-reaction immunity in mice and increase antitumor activity. Sera of mice were analyzed and IgG antibody titer in MLB group was obviously higher than other groups including the mice immunized with liposomal bFGF vaccine, bFGF plus Freund's adjuvant, empty liposome and PBS. Furthermore, tumor metastasis was significantly inhibited in MLB group, compared with L and PBS group. The IFN-γ production of cultured splenocytes in vitro was evidently up-regulated meanwhile IL-4 production sustained in a low level, revealing that this vaccine stimulated Th1 immunity response preferentially. Taken together, these findings suggested that this novel bFGF vaccine could effectively induce humoral immunity through cross-reaction, mediate Th1 immune response preferentially and enhance antitumor activity in vivo.

Isolation and potential immunological characterization of TPSGLVY, a novel bursal septpeptide isolated from the bursa of Fabricius

The bursa of Fabricius is central immune organ unique to birds, and the extract is immunocompetent in stimulating B cell differentiation and enhancing antibody production. However, except for bursin, the active peptides from the bursa of Fabricius are little reported. In the paper, a novel bursal septpeptide (BSP-II) with the amino acids sequence of TPSGLVY was identified and similar to the MGC53864 protein of Gallus gallus. We investigated the effects of BSP-II on the immune response in terms of the antibodies titers (IgG1 and IgG2alpha), the levels of interferon-gamma and interleukin-4 cytokines, spleen cell lymphocyte proliferation, and the T-lymphocyte subtype composition. It was noteworthy that BSP-II potentiates the Th1 and Th2-type immune responses in dose-dependent manner. BSP-II had specific enhancing effects on the hybridoma SP2/0 cell proliferation at two different serum concentrations (20% and 5%), but had no connection with the dose of BSP-II. The antibody secreting level of hybridoma SP2/0 cells rose in 5% and 20% serum when the concentrations of BSP-II increased. Also, BSP-II had effect on the viabilities of tumor cells (Hela and SP2/0). All the results indicated that BSP-II was able to significantly induce various immune responses and involved in the cell viability of different tumor cell lines. Our observations implied that BSP-II might be a novel biological active factor from the bursa of Fabricius with immunomodulatory activities.

Boswellia resin: from religious ceremonies to medical uses; a review of in-vitro, in-vivo and clinical trials

Objectives

Despite its historical-religious, cultural and medical importance, Boswellia has not been thoroughly studied, and gaps still exist between our knowledge of the traditional uses of the resin and the scientific data available. Here we review the pharmacology of Boswellia resin and of the small molecules identified as the active ingredients of the resin.

Key findings

The resin of Boswellia species (‘frankincense’, ‘olibanum’) has been used as incense in religious and cultural ceremonies since the beginning of written history. Its medicinal properties are also widely recognized, mainly in the treatment of inflammatory conditions, as well as in some cancerous diseases, wound healing and for its antimicrobial activity. Until recently, work on Boswellia focused on the immunomodulatory properties of the resin and boswellic acids were considered to be the main, if not the only, active ingredients of the resin. Hence, this family of triterpenoids was investigated by numerous groups, both in vitro and in vivo. These compounds were shown to exert significant anti-inflammatory and pro-apoptotic activity in many assays: in vitro, in vivo and in clinical trials. We recently found incensole acetate and its derivatives, which are major components of Boswellia resin, to be nuclear factor-κB inhibitors, thus suggesting that they are, at least in part, responsible for its anti-inflammatory effects. Incensole acetate also exerts a robust neuroprotective effect after brain trauma in mice. Furthermore, it causes behavioural as well as anti-depressive and anxiolytic effects in mice. It is also a potent agonist of the transient receptor potential (TRP)V3 channel. It thus seems that incensole acetate and its derivatives play a significant role in the effects that Boswellia resin exerts on biological systems.

Conclusions

Altogether, studies on Boswellia resin have provided an arsenal of bio-active small molecules with a considerable therapeutic potential that is far from being utilized.

Boswellic acids: a group of medicinally important compounds

This review, containing over 276 references, covers the progress made in the chemistry and bioactivity of this important group of triterpenoids. Though initially known for their anti-inflammatory and anti-arthritic activities through a unique 5-LO inhibition mechanism, boswellic acids have recently attained significance due to their anti-cancer properties. The phytochemistry and chemical modifications, including mechanism of action, are discussed.

Lipid A mimetics are potent adjuvants for an intranasal pneumonic plague vaccine

An effective intranasal (i.n.) vaccine against pneumonic plague was developed. The formulation employed two synthetic lipid A mimetics as adjuvant combined with Yersinia pestis-derived V- and F1-protective antigens. The two nontoxic lipid A mimetics, classed as amino-alkyl glucosaminide 4-phosphates (AGPs) are potent ligands for the Toll-like receptor (TLR) 4. Using a murine (BALB/c) pneumonic plague model, we showed a single i.n. application of the vaccine provided 63% protection within 21 days against a Y. pestis CO92 100 LD50 challenge. Protection reached 100% by 150 days. Using a homologous i.n. 1 degrees /2 degrees dose regimen, with the boost administered at varying times, 63% protection was achieved within 7 days and 100% protection was achieved by 21 days after the first immunization. Little or no protection was observed in animals that received antigens alone, and no protection was observed when the vaccine was administered to BALB/c TLR4 mutant mice. Vaccine-induced serum IgG titers to F1 and V-antigen were reflected in high titers for IgG1 and IgG2a, the latter reflecting a bias for a cell-mediated (TH1) immune response. This intranasal vaccine showed 90% protection in Sprague-Dawley rats challenged with 1000 LD50. We conclude that lipid A mimetics are highly effective adjuvants for an i.n. plague vaccine.

Evaluation of recombinant Onchocerca volvulus activation associated protein-1 (ASP-1) as a potent Th1-biased adjuvant with a panel of protein or peptide-based antigens and commercial inactivated vaccines

Alum, the only adjuvant approved for clinical applications, can induce strong humoral (Th2) but weak cellular (Th1) immune responses. It is necessary to develop safe and effective adjuvants capable of inducing both humoral and cellular immune responses. We previously showed that activation-associated protein-1 (ASP-1) derived from Onchocerca volvulus has potent adjuvant activity. In this study, we have further evaluated the adjuvanticity of recombinant ASP-1 using a panel of recombinant proteins or synthetic peptide-based antigens, including ovalbumin (OVA), synthetic HIV peptide (HIV-p), recombinant HIV gp41 (rgp41) and HBV HBsAg, as well as three commercially available inactivated vaccines against haemorrhagic fever with renal syndrome (HFRS), Influenza and Rabies. Our results indicate that ASP-1 induced significantly higher IgG1 (Th2-associated) and IgG2a (Th1-associated) responses than alum adjuvant against OVA antigen, HIV-p, and rgp41. Consistently, it induced similar level of IgG1 responses as alum but higher level of IgG2a and IFN-gamma-producing T cell responses than alum adjuvant against HBsAg. Further, ASP-1 improved both IgG1 and IgG2a responses to three commercial inactivated vaccines when used separately or in combination. In conclusion, the recombinant ASP-1, unlike alum adjuvant, is able to induce both Th1 and Th2-associated humoral responses and Th1 cellular responses, suggesting that it can be further developed as a promising adjuvant for subunit-based and inactivated vaccines.

Pre-clinical evaluation of a novel nanoemulsion-based hepatitis B mucosal vaccine

BACKGROUND

Hepatitis B virus infection remains an important global health concern despite the availability of safe and effective prophylactic vaccines. Limitations to these vaccines include requirement for refrigeration and three immunizations thereby restricting use in the developing world. A new nasal hepatitis B vaccine composed of recombinant hepatitis B surface antigen (HBsAg) in a novel nanoemulsion (NE) adjuvant (HBsAg-NE) could be effective with fewer administrations.

METHODOLOGY AND PRINCIPAL FINDINGS

Physical characterization indicated that HBsAg-NE consists of uniform lipid droplets (349+/-17 nm) associated with HBsAg through electrostatic and hydrophobic interactions. Immunogenicity of HBsAg-NE vaccine was evaluated in mice, rats and guinea pigs. Animals immunized intranasally developed robust and sustained systemic IgG, mucosal IgA and strong antigen-specific cellular immune responses. Serum IgG reached > or = 10(6) titers and was comparable to intramuscular vaccination with alum-adjuvanted vaccine (HBsAg-Alu). Normalization showed that HBsAg-NE vaccination correlates with a protective immunity equivalent or greater than 1000 IU/ml. Th1 polarized immune response was indicated by IFN-gamma and TNF-alpha cytokine production and elevated levels of IgG(2) subclass of HBsAg-specific antibodies. The vaccine retains full immunogenicity for a year at 4 degrees C, 6 months at 25 degrees C and 6 weeks at 40 degrees C. Comprehensive pre-clinical toxicology evaluation demonstrated that HBsAg-NE vaccine is safe and well tolerated in multiple animal models.

CONCLUSIONS

Our results suggest that needle-free nasal immunization with HBsAg-NE could be a safe and effective hepatitis B vaccine, or provide an alternative booster administration for the parenteral hepatitis B vaccines. This vaccine induces a Th1 associated cellular immunity and also may provide therapeutic benefit to patients with chronic hepatitis B infection who lack cellular immune responses to adequately control viral replication. Long-term stability of this vaccine formulation at elevated temperatures suggests a direct advantage in the field, since potential excursions from cold chain maintenance could be tolerated without a loss in therapeutic efficacy.