Nanoemulsion mucosal adjuvant uniquely activates cytokine production by nasal ciliated epithelium and induces dendritic cell trafficking

W/O/W Microemulsions for Nasal Delivery of Hydrophilic Compounds: A Preliminary Study

The administration of hydrophilic therapeutics has always been a great challenge because of their low bioavailability after administration. For this purpose, W/O/W microemulsion resulted to be a potential successful strategy for the delivery of hydrophilic compounds, interesting for the nasal mucosal therapy. Herein, an optimized biphasic W/O microemulsion was designed, through a preliminary screening, and it was inverted in a triphasic W/O/W microemulsion, intended for the nasal administration. In order to enhance the mucosal retention, surface modification of the biphasic W/O microemulsion was performed adding didodecyldimethylammonium bromide, and then converting the system into a cationic triphasic W/O/W microemulsion. The developed samples were characterized in terms of droplet size, polydispersity, zeta potential, pH and osmolality. The physical long-term stability was analyzed storing samples at accelerated conditions (40 ± 2 °C and 75 ± 5 % RH) for 6 months in a constant climate chamber, following ICH guidelines Q1A (R2). In order to verify the potential retention on the nasal mucosa, the two triphasic systems were analyzed in terms of mucoadhesive properties, measuring the in vitro interaction with mucin over time. Furthermore, fluorescein sodium salt was selected as a model hydrophilic drug to be encapsulated into the inner core of the two triphasic W/O/W microemulsions, and its release was analyzed compared to the free probe solution. The cytocompatibility of the two platforms was assessed on two cell lines, human fibroblasts HFF1 and Calu-3 cell lines, chosen as pre-clinical models for nasal and bronchial/tracheal airway epithelium.

Enhanced Influenza Immunity by Nasal Mucosal Administration of the TPGS-Modified Liposomal Vaccine

Influenza infection is difficult to prevent, control, and treat because of rapid viral mutation, fast disease progression, and high mortality. Vaccination is the main means by which to prevent and control influenza, but effectiveness is limited in that poor cellular uptake and weak immunogenicity of vaccines provides less than optimal host protection. Liposomal influenza vaccines are a promising strategy to overcome these limitations and the use of liposomal immune modulators and intranasal administration of liposomal influenza vaccines may be a means by which to improve influenza protection. The cationic lipids, i.e., dimethyldioctadecylammonium (DDA), 1,2-dioctadecanoyl-sn-glycero-3-phosphocholine (DSPC), and D-α-tocopherol polyethylene glycol 1000 (TPGS) can form blank liposomes, which can incorporate influenza antigens to produce an influenza vaccine (DDA-DSPC-TPGS). Herein, this vaccine was shown to induce dendritic cell maturation, increase host cellular uptake of the vaccine, and enhance immune responses both in vitro and in vivo. The addition of TPGS, as an amphiphilic immune adjuvant, significantly reduced the toxicity of the DDA liposomal influenza vaccine. Further, the polyethylene glycol component and tocopherol structure of TPGS enhanced the cellular uptake of the vaccine by means of stealth properties and the capacity to inhibit cellular efflux. After nasal mucosal immunization, enhanced cellular uptake rates and abundant immune cells in the nasopharyngeal-associated lymphoid tissue promoted the production of immunoglobulin A, immunoglobulin G1, and interferon-γ, which in turn mediated a more robust immune response against influenza virus. In summary, the DDA-DSPC-TPGS influenza vaccine is a safe and effective means by which to activate the immune system. The results herein provide an effective strategy by which to overcome current difficulties associated with the prevention and treatment of influenza.

Intranasal vaccine: Factors to consider in research and development

Most existing vaccines for human use are administered by needle-based injection. Administering vaccines needle-free intranasally has numerous advantages over by needle-based injection, but there are only a few intranasal vaccines that are currently approved for human use, and all of them are live attenuated influenza virus vaccines. Clearly, there are immunological as well as non-immunological challenges that prevent vaccine developers from choosing the intranasal route of administration. We reviewed current approved intranasal vaccines and pipelines and described the target of intranasal vaccines, i.e. nose and lymphoid tissues in the nasal cavity. We then analyzed factors unique to intranasal vaccines that need to be considered when researching and developing new intranasal vaccines. We concluded that while the choice of vaccine formulations, mucoadhesives, mucosal and epithelial permeation enhancers, and ligands that target M-cells are important, safe and effective intranasal mucosal vaccine adjuvants are needed to successfully develop an intranasal vaccine that is not based on live-attenuated viruses or bacteria. Moreover, more effective intranasal vaccine application devices that can efficiently target a vaccine to lymphoid tissues in the nasal cavity as well as preclinical animal models that can better predict intranasal vaccine performance in clinical trials are needed to increase the success rate of intranasal vaccines in clinical trials.

A Combination Adjuvant for the Induction of Potent Antiviral Immune Responses for a Recombinant SARS-CoV-2 Protein Vaccine

Several SARS-CoV-2 vaccines have received EUAs, but many issues remain unresolved, including duration of conferred immunity and breadth of cross-protection. Adjuvants that enhance and shape adaptive immune responses that confer broad protection against SARS-CoV-2 variants will be pivotal for long-term protection as drift variants continue to emerge. We developed an intranasal, rationally designed adjuvant integrating a nanoemulsion (NE) that activates TLRs and NLRP3 with an RNA agonist of RIG-I (IVT DI). The combination adjuvant with spike protein antigen elicited robust responses to SARS-CoV-2 in mice, with markedly enhanced TH1-biased cellular responses and high virus-neutralizing antibody titers towards both homologous SARS-CoV-2 and a variant harboring the N501Y mutation shared by B1.1.7, B.1.351 and P.1 variants. Furthermore, passive transfer of vaccination-induced antibodies protected naive mice against heterologous viral challenge. NE/IVT DI enables mucosal vaccination, and has the potential to improve the immune profile of a variety of SARS-CoV-2 vaccine candidates to provide effective cross-protection against future drift variants.

Nasal Immunization With Small Molecule Mast Cell Activators Enhance Immunity to Co-Administered Subunit Immunogens

Mast cell activators are a novel class of mucosal vaccine adjuvants. The polymeric compound, Compound 48/80 (C48/80), and cationic peptide, Mastoparan 7 (M7) are mast cell activators that provide adjuvant activity when administered by the nasal route. However, small molecule mast cell activators may be a more cost-efficient adjuvant alternative that is easily synthesized with high purity compared to M7 or C48/80. To identify novel mast cell activating compounds that could be evaluated for mucosal vaccine adjuvant activity, we employed high-throughput screening to assess over 55,000 small molecules for mast cell degranulation activity. Fifteen mast cell activating compounds were down-selected to five compounds based on in vitro immune activation activities including cytokine production and cellular cytotoxicity, synthesis feasibility, and selection for functional diversity. These small molecule mast cell activators were evaluated for in vivo adjuvant activity and induction of protective immunity against West Nile Virus infection in BALB/c mice when combined with West Nile Virus envelope domain III (EDIII) protein in a nasal vaccine. We found that three of the five mast cell activators, ST101036, ST048871, and R529877, evoked high levels of EDIII-specific antibody and conferred comparable levels of protection against WNV challenge. The level of protection provided by these small molecule mast cell activators was comparable to the protection evoked by M7 (67%) but markedly higher than the levels seen with mice immunized with EDIII alone (no adjuvant 33%). Thus, novel small molecule mast cell activators identified by high throughput screening are as efficacious as previously described mast cell activators when used as nasal vaccine adjuvants and represent next-generation mast cell activators for evaluation in mucosal vaccine studies.

Intranasal delivery of allergen in a nanoemulsion adjuvant inhibits allergen-specific reactions in mouse models of allergic airway disease

BACKGROUND

Atopic diseases are an increasing problem that involve both immediate hypersensitivity reactions mediated by IgE and unique cellular inflammation. Many forms of specific immunotherapy involve the administration of allergen to suppress allergic immune responses but are focused on IgE-mediated reactions. In contrast, the effect of allergen-specific immunotherapy on allergic inflammation is complex, not entirely consistent and not well understood. We have previously demonstrated the ability of allergen administered in a nanoemulsion (NE) mucosal adjuvant to suppress IgE-mediated allergic responses and protect from allergen challenge in murine food allergy models. This activity was associated with decreases in allergen-specific IL-10 and reductions in allergic cytokines and increases in regulatory T cells.

OBJECTIVE

Here, we extend these studies to using 2 distinct models, the ovalbumin (OVA) and cockroach (CRA) models of allergic airway disease, which are based predominantly on allergic inflammation.

METHODS

Acute or chronic allergic airway disease was induced in mice using ovalbumin and cockroach allergen models. Mice received three therapeutic immunizations with allergen in NE, and reactivity to airway challenge was determined.

RESULTS

Therapeutic immunization with cockroach or OVA allergen in NE markedly reduced pathology after airway challenge. The 2 models demonstrated protection from allergen challenge-induced pathology that was associated with suppression of Th2-polarized immune responses in the lung. In addition, the reduction in ILC2 numbers in the lungs of allergic mice along with reduction in epithelial cell alarmins, IL-25 and IL-33, suggests an overall change in the lung immune environment induced by the NE immunization protocol.

CONCLUSIONS AND CLINICAL RELEVANCE

These results demonstrate that suppression of allergic airway inflammation and bronchial hyper-reactivity can be achieved using allergen-specific immunotherapy without significant reductions in allergen-specific IgE and suggest that ILC2 cells may be critical targets for this activity.

A Combination Adjuvant for the Induction of Potent Antiviral Immune Responses for a Recombinant SARS-CoV-2 Protein Vaccine

Several SARS-CoV-2 vaccines have received EUAs, but many issues remain unresolved, including duration of conferred immunity and breadth of cross-protection. Adjuvants that enhance and shape adaptive immune responses that confer broad protection against SARS-CoV-2 variants will be pivotal for long-term protection. We developed an intranasal, rationally designed adjuvant integrating a nanoemulsion (NE) that activates TLRs and NLRP3 with an RNA agonist of RIG-I (IVT DI). The combination adjuvant with spike protein antigen elicited robust responses to SARS-CoV-2 in mice, with markedly enhanced T _H 1-biased cellular responses and high virus-neutralizing antibody titers towards both homologous SARS-CoV-2 and a variant harboring the N501Y mutation shared by B1.1.7, B.1.351 and P.1 variants. Furthermore, passive transfer of vaccination-induced antibodies protected naive mice against heterologous viral challenge. NE/IVT DI enables mucosal vaccination, and has the potential to improve the immune profile of a variety of SARS-CoV-2 vaccine candidates to provide effective cross-protection against future drift variants.

Silicone Oil-Based Nanoadjuvants as Candidates for a New Formulation of Intranasal Vaccines

Many conventional vaccines are administered via a needle injection, while most pathogens primarily invade the host via mucosal surfaces. Moreover, protective IgA antibodies are insufficiently induced by parenteral vaccines. Mucosal immunity induces both local and systemic response to pathogens and typically lasts for long periods of time. Therefore, vaccination via mucosal routes has been increasingly explored. However, mucosal vaccines require potent adjuvants to become efficacious. Despite many efforts to develop safe and robust adjuvants for mucosal vaccines, only a few have been approved for use in human formulations. The aim of our study was to design, develop and characterize new silicone oil-based nanoadjuvant candidates for intranasal vaccines with potential to become mucosal adjuvants. We have developed an array of nanoadjuvant candidates (NACs), based on well-defined ingredients. NAC1, 2 and 3 are based on silicone oil, but differ in the used detergents and organic solvents, which results in variations in their droplet size and zeta potential. NACs' cytotoxicity, Tumor Necrosis Factor α (TNF-α) induction and their effect on antigen engulfment by immune cells were tested in vitro. Adjuvant properties of NACs were verified by intranasal vaccination of mice together with ovalbumin (OVA). NACs show remarkable stability and do not require any special storage conditions. They exhibit bio-adhesiveness and influence the degree of model protein engulfment by epithelial cells. Moreover, they induce high specific anti-OVA IgG antibody titers after two intranasal administrations. Nanoadjuvant candidates composed of silicone oil and cationic detergents are stable, exhibit remarkable adjuvant properties and can be used as adjuvants for intranasal immunization.

Vaccines as therapies for food allergies

Food allergy is a growing public health epidemic with few available treatments beyond allergen avoidance and rescue medications for accidental exposures. A major focus of therapeutic development for food allergies is allergen-specific immunotherapy (AIT) in which patients are exposed to increasing amounts of allergen in controlled dosing to induce desensitization or tolerance. The work of the past few decades has culminated in the recent FDA approval of a peanut product for oral AIT for peanut allergies. Despite these advances, current AIT protocols are cumbersome, take a long time to reach clinical benefit and often have significant side effects. Therefore, there is a great need to develop new therapeutics for food allergy. One area of research aims to improve AIT through the use of adjuvants which are substances traditionally added to vaccines to stimulate or direct a specific immune response. Adjuvants that induce Th1-polarized and regulatory immune responses while suppressing Th2 immunity have shown the most promise in animal models. The addition of adjuvants to AIT may reduce the amount and frequency of allergen required to achieve clinical benefit and may induce more long-lasting immune responses. In this chapter, we highlight examples of adjuvanted AIT and vaccines in development to treat food allergies.

Mucosal Nanoemulsion Allergy Vaccine Suppresses Alarmin Expression and Induces Bystander Suppression of Reactivity to Multiple Food Allergens

We have demonstrated that intranasal immunotherapy with allergens formulated in a nanoemulsion (NE) mucosal adjuvant suppresses Th2/IgE-mediated allergic responses and protects from allergen challenge in murine food allergy models. Protection conferred by this therapy is associated with strong suppression of allergen specific Th2 cellular immunity and increased Th1 cytokines. Here we extend these studies to examine the effect of NE-allergen immunization in mice sensitized to multiple foods. Mice were sensitized to both egg and peanut and then received NE vaccine formulated with either one or both of these allergens. The animals were then subjected to oral challenges with either egg or peanut to assess reactivity. Immunization with NE formulations containing both egg and peanut markedly reduced reactivity after oral allergen challenge with either allergen. Interestingly, mice that received the vaccine containing only peanut also had reduced reactivity to challenge with egg. Protection from oral allergen challenge was achieved despite the persistence of allergen-specific IgE and was associated with strong suppression of both Th2-polarized immune responses, alarmins and type 2 innate lymphoid cells (ILC2). NE-induced bystander suppression of reactivity required IFN-γ and the presence of an allergen in the NE vaccine. These results demonstrate that anaphylactic reactions to food allergens can be suppressed using allergen-specific immunotherapy without having to eliminate allergen-specific IgE and suggests that modulation of Th2 immunity towards one allergen may induce bystander effects that suppress reactivity to other allergens through the induction of IFN-γ and suppression of alarmins in the intestine. In addition, these data suggest that a NE vaccine for a single food allergen may lead to a global suppression of allergic responses to multiple foods.

Combined Intranasal Nanoemulsion and RIG-I Activating RNA Adjuvants Enhance Mucosal, Humoral, and Cellular Immunity to Influenza Virus

Current influenza virus vaccines are focused on humoral immunity and are limited by the short duration of protection, narrow cross-strain efficacy, and suboptimal immunogenicity. Here, we combined two chemically and biologically distinct adjuvants, an oil-in-water nanoemulsion (NE) and RNA-based agonists of RIG-I, to determine whether the diverse mechanisms of these adjuvants could lead to improved immunogenicity and breadth of protection against the influenza virus. NE activates TLRs, stimulates immunogenic apoptosis, and enhances cellular antigen uptake, leading to a balanced T_H1/T_H2/T_H17 response when administered intranasally. RIG-I agonists included RNAs derived from Sendai and influenza viral defective interfering RNAs (IVT DI, 3php, respectively) and RIG-I/TLR3 agonist, poly(I:C) (pIC), which induce IFN-Is and T_H1-polarized responses. NE/RNA combined adjuvants potentially allow for costimulation of multiple innate immune receptor pathways, more closely mimicking patterns of activation occurring during natural viral infection. Mice intranasally immunized with inactivated A/Puerto Rico/8/1934 (H1N1) (PR/8) adjuvanted with NE/IVT DI or NE/3php (but not NE/pIC) showed synergistic enhancement of systemic PR/8-specific IgG with significantly greater avidity and virus neutralization activity than the individual adjuvants. Notably, NE/IVT DI induced protective neutralizing titers after a single immunization. Hemagglutinin stem-specific antibodies were also improved, allowing recognition of heterologous and heterosubtypic hemagglutinins. All NE/RNAs elicited substantial PR/8-specific sIgA. Finally, a unique cellular response with enhanced T_H1/T_H17 immunity was induced with the NE/RNAs. These results demonstrate that the enhanced immunogenicity of the adjuvant combinations was synergistic and not simply additive, highlighting the potential value of a combined adjuvant approach for improving the efficacy of vaccination against the influenza virus.

Solid-in-oil nanodispersions for intranasal vaccination: Enhancement of mucosal and systemic immune responses

En masse vaccination is a promising strategy for combatting infectious diseases. Intranasal vaccination is a viable route of mass vaccination, and it could be performed easily via needle-free administration. However, it is not widely used because it tends not to evoke sufficient immunity. The aim of the present study was to improve the performance of intranasal vaccination by extending the amount of time that administered antigens remain in the nasal cavity, and enhancing immune responses via a nanocarrier-based adjuvant. A simple and safe solid-in-oil (S/O) system was investigated as a nanocarrier in intranasal vaccination. S/O nanodispersions are oil-based dispersions of antigens coated with surfactants. Because of the mucoadhesive capacities of surfactant and oil they have high potential to extend the amount of time that administered antigens remain in the nasal cavity, and can induce strong immune responses due to a nanocarrier-based adjuvant effect. In nasal absorption experiments antigens administered intranasally via S/O nanodispersions remained in the nasal cavity longer and induced strong mucosal and systemic immune responses. Histopathology analysis indicated that S/O nanodispersions did not modify the nasal epithelium or cilia, suggesting non-toxicity of the carrier. These results indicate the potential of intranasal vaccination using S/O nanodispersions for future vaccination.

Intranasal nanoemulsion-adjuvanted HSV-2 subunit vaccine is effective as a prophylactic and therapeutic vaccine using the guinea pig model of genital herpes

Genital herpes is a sexually transmitted disease representing a major global health concern. Currently, there is no approved vaccine and existing antiviral therapies exhibit limited efficacy. Herein, we describe an intranasal (IN) vaccine comprised of HSV-2 surface glycoproteins gD2 and gB2 formulated in a nanoemulsion adjuvant (NE01-gD2/gB2). Using the HSV-2 genital herpes guinea pig model, we demonstrate that IN NE01-gD2/gB2 induces higher levels of neutralizing antibody compared to a monovalent IN NE01-gD2 vaccine, but less than an intramuscular (IM) Alum/MPL-gD2 vaccine. Following intravaginal (IVag) challenge with HSV-2, the group immunized with IN NE01-gD2/gB2 exhibited significantly reduced acute and recurrent disease scores compared to placebo recipients. Significantly, latent virus was only detected in the dorsal root ganglia of 1 of 12 IN NE01-gD2/gB2-vaccinated animals compared to 11 of 12 placebo recipient. In the therapeutic model, IN NE01-gD2/gB2 immunized guinea pigs exhibited a significant reduction in the recurrent lesions scores (64%, p < 0.01), number of animal days with disease (64%, p < 0.01), number of animals with viral shedding (50%, p < 0.04) and reduction in virus positive vaginal swabs (56%, p < 0.04), These data suggests that the treatment may be effective in treating chronic disease and minimizing virus transmission. These results warrant advancing the development of IN NE01-gD2/gB2 as both a prophylactic and therapeutic vaccine against HSV-2.

A nanoemulsion-adjuvanted intranasal H5N1 influenza vaccine protects ferrets against homologous and heterologous H5N1 lethal challenge

BACKGROUND

Flu vaccines administered intramuscularly (IM) have shown seasonally fluctuating efficacy, 20-60%, throughout the last 15 years. We formulated a recombinant H5 (rH5) in our Nanovax® (NE01) (rH5/NE01) adjuvant for intranasal vaccination in ferrets. We evaluated the regimen, one vs two immunization, and cross clade protection a ferret challenge model.

METHODS

Plant derived recombinant H5 (rH5) antigen was formulated with NE01 and administered intranasally to ferrets. Immunogenicity (IgG), hemagglutination inhibition (HI), and protection against lethal challenge, were measured following one or two immunizations. Protection against homologous (strain A/Indo) and heterologous (strain A/Vn) was evaluated in ferrets following two immunizations.

RESULTS

IN immunization with rH5/NE01 induced significant IgG levels after one and two immunizations. One vaccination did not induce any HI while low HI was measured after two immunizations. Homologous challenge with H5N1 A/ Indonesia showed 100% survival, with minimal weight loss in animals vaccinated twice compared to the unvaccinated controls. Analysis of nasal wash from these challenged ferrets vaccinated twice showed decreased viral shedding compared to unvaccinated controls. Interestingly, animals that received one vaccination showed 88% survival with moderate weight loss. Cross clade protection was evaluated using an increased antigen dose (45 µg rH5). Vaccinated animals demonstrated increased IgG and HAI antibody responses. Both homologous (A/Indo) and heterologous challenge (A/Vietnam) following two immunizations showed 100% survival with no loss of body weight. However viral clearance was more rapid against the homologous (day 3) compared to the heterologous (day 5) post challenge.

CONCLUSION

Intranasal administration of NE01 adjuvant-formulated rH5 vaccine elicited systemic and probably mucosal immunity that conferred protection against lethal challenge with homologous or heterologous viral strains. It also enhanced viral clearance with decreased shedding. These outcomes strongly suggest that intranasal immunization using NE01 against flu infections warrants clinical testing.

Innovative Mucosal Vaccine Formulations Against Influenza A Virus Infections

Despite efforts made to develop efficient preventive strategies, infections with influenza A viruses (IAV) continue to cause serious clinical and economic problems. Current licensed human vaccines are mainly inactivated whole virus particles or split-virion administered via the parenteral route. These vaccines provide incomplete protection against IAV in high-risk groups and are poorly/not effective against the constant antigenic drift/shift occurring in circulating strains. Advances in mucosal vaccinology and in the understanding of the protective anti-influenza immune mechanisms suggest that intranasal immunization is a promising strategy to fight against IAV. To date, human mucosal anti-influenza vaccines consist of live attenuated strains administered intranasally, which elicit higher local humoral and cellular immune responses than conventional parenteral vaccines. However, because of inconsistent protective efficacy and safety concerns regarding the use of live viral strains, new vaccine candidates are urgently needed. To prime and induce potent and long-lived protective immune responses, mucosal vaccine formulations need to ensure the immunoavailability and the immunostimulating capacity of the vaccine antigen(s) at the mucosal surfaces, while being minimally reactogenic/toxic. The purpose of this review is to compile innovative delivery/adjuvant systems tested for intranasal administration of inactivated influenza vaccines, including micro/nanosized particulate carriers such as lipid-based particles, virus-like particles and polymers associated or not with immunopotentiatory molecules including microorganism-derived toxins, Toll-like receptor ligands and cytokines. The capacity of these vaccines to trigger specific mucosal and systemic humoral and cellular responses against IAV and their (cross)-protective potential are considered.

Nanoemulsion Adjuvant Augments Retinaldehyde Dehydrogenase Activity in Dendritic Cells via MyD88 Pathway

Mucosal surfaces are the primary point of entry for many infectious agents and mucosal immune responses serve as the primary defense to these pathogens. In order to mount an effective mucosal immune response, it is important to induce T cell homing to mucosal surfaces. Conventional vaccine adjuvants induce strong systemic immunity but often fail to produce mucosal immunity. We have developed an oil-in-water nanoemulsion (NE) adjuvant that provides mucosal immunity and efficient protection against mucosal pathogens when administered as part of an intranasal vaccine. In the present study, we demonstrate that intranasal immunization with NE indirectly activates the retinaldehyde dehydrogenase (RALDH) activity in dendritic cells through epithelial cell activity leading to SIgA as well as potent cellular responses and expression of α4β7 and CCR9 gut homing receptors on T cells. Confirming these findings, ex-vivo stimulation of splenocytes from NE nasally immunized animals showed increase in Th1/Th17 cytokines while suppressing Th2 responses. In examining mechanisms underlying this activation NE activated RALDH via MyD88 dependent pathways in DCs but did not activate the retinoic acid receptor directly. These results suggest that RALDH immune activities can be achieved by epithelial activation without direct RAR activation, which has significant implications for understanding mucosal immunity and the design of mucosal vaccines.

Tomato lectin-modified nanoemulsion-encapsulated MAGE1-HSP70/SEA complex protein vaccine: Targeting intestinal M cells following peroral administration

Vaccines administered orally enable the stimulation of both the mucous membrane and system immune responses. However, tumor vaccines, whose effective elements are antigen protein molecules or gene-encoding antigens, are hardly accustomed to the harsh gastrointestinal environment. Here, we explored an oral nanoecapsulated tumor vaccine complex to evaluate the anti-tumor effect. Tomato lectin (TL) was modified on the surface of a nanoemulsion (NE) composed of MAGE1-HSP70/SEA (MHS). C57BL/6 mice were immunized with NE (-), NE (MHS) and TL-NE (MHS) via po. or sc. administration. Additionally, the cellular immunocompetence was detected by the enzyme-linked immunospot assay and lactate dehydrogenase release assay. Serum antibody titers were analyzed using the enzyme-linked immuno sorbent assay. Next, the therapeutic and tumor challenge assays were performed. The TL-NE (MHS) particles were 20 ± 5 nm in diameter and could resist pepsin and trypsin digestion. The cellular immune responses elicited by TL-NE (MHS) perioral were stronger than those by TL-NE (MHS)-sc. (p < 0.05) when targeted to B16-MAGE1 tumor cells. The levels of MAGE-1 antibody induced by TL-NE (MHS) via the oral route was higher than control group (p < 0.05). The percentage of CD4+ and CD8+ T cells in TL-NE (MHS)-po. group was more than other groups (p < 0.05). Furthermore, oral TL-NE (M)HScould delay tumor growth and defer tumor occurrence and tumor recurrence after resection in mice challenged with B16-MAGE-1 tumor cells. The study suggested that the oral TL-NE (MHS) vaccine delivery system is feasible to improve the vaccine protection effect and may have broad application in cancer therapy.

Nasal Administration of Cationic Nanoemulsions as Nucleic Acids Delivery Systems Aiming at Mucopolysaccharidosis Type I Gene Therapy

PURPOSE

This study demonstrates the nasal administration (NA) of nanoemulsions complexed with the plasmid encoding for IDUA protein (pIDUA) as an attempt to reach the brain aiming at MPS I gene therapy.

METHODS

Formulations composed of DOPE, DOTAP, MCT (NE), and DSPE-PEG (NE-PEG) were prepared by high-pressure homogenization, and assessed in vitro on human fibroblasts from MPS I patients and in vivo on MPS I mice for IDUA production and gene expression.

RESULTS

The physicochemical results showed that the presence of DSPE-PEG in the formulations led to smaller and more stable droplets even when submitted to dilution in simulated nasal medium (SNM). In vitro assays showed that pIDUA/NE-PEG complexes were internalized by cells, and led to a 5% significant increase in IDUA activity, besides promoting a two-fold increase in IDUA expression. The NA of pIDUA/NE-PEG complexes to MPS I mice demonstrated the ability to reach the brain, promoting increased IDUA activity and expression in this tissue, as well as in kidney and spleen tissues after treatment. An increase in serum IL-6 was observed after treatment, although with no signs of tissue inflammatory infiltrate according to histopathology and CD68 assessments.

CONCLUSIONS

These findings demonstrated that pIDUA/NE-PEG complexes could efficiently increase IDUA activity in vitro and in vivo after NA, and represent a potential treatment for the neurological impairment present in MPS I patients.

Intranasal delivery of nanoparticle-based vaccines

Most pathogens gain access to the human body and initiate systemic infections through mucosal sites. A large number of currently marketed licensed vaccines are parenterally administered; they generate strong systemic immunity but not mucosal immunity. Nasal vaccination is an appealing strategy for the induction of mucosal-specific immunity; however, its development is mostly challenged by several factors, such as inefficient antigen uptake, its rapid mucociliary clearance, size-restricted permeation across epithelial barriers and absence of safe human mucosal adjuvants. Therefore, a safer mucosal-adjuvanting strategy or efficient mucosal delivery platform is much warranted. This review summarizes challenges and the rationale for nasal vaccine development with a special focus on the use of nanoparticles based on polymers and lipids for mucosal vaccine delivery.

Nanoemulsion adjuvant-driven redirection of TH2 immunity inhibits allergic reactions in murine models of peanut allergy

BACKGROUND

Immunotherapy for food allergies involves progressive increased exposures to food that result in desensitization to food allergens in some subjects but not tolerance to the food. Therefore new approaches to suppress allergic immunity to food are necessary. Previously, we demonstrated that intranasal immunization with a nanoemulsion (NE) adjuvant induces robust mucosal antibody and T_H17-polarized immunity, as well as systemic T_H1-biased cellular immunity with suppression of pre-existing T_H2-biased immunity.

OBJECTIVE

We hypothesized that immunization with food in conjunction with the nanoemulsion adjuvant could lead to modulation of allergic reactions in food allergy by altering pre-existing allergic immunity and enhancing mucosal immunity.

METHODS

Mice were sensitized to peanut with aluminum hydroxide or cholera toxin. The animals were then administered 3 monthly intranasal immunizations with peanut in the nanoemulsion adjuvant or saline. Mice were then challenged with peanut to examine allergen reactivity.

RESULTS

The NE intranasal immunizations resulted in marked decreases in T_H2 cytokine, IgG₁, and IgE levels, whereas T_H1 and mucosal T_H17 immune responses were increased. After allergen challenge, these mice showed significant reductions in allergic hypersensitivity. Additionally, the NE immunizations significantly increased antigen-specific IL-10 production and regulatory T-cell counts, and the protection induced by NE was dependent in part on IL-10. Control animals immunized with intranasal peanut in saline had no modulation of their allergic response.

CONCLUSIONS

NE adjuvant-mediated induction of mucosal T_H17 and systemic T_H1-biased immunity can suppress T_H2-mediated allergy through multiple mechanisms and protect against anaphylaxis. These results suggest the potential therapeutic utility of this approach in the setting of food allergy.

Lipid-Based Particles: Versatile Delivery Systems for Mucosal Vaccination against Infection

Vaccination is the process of administering immunogenic formulations in order to induce or harness antigen (Ag)-specific antibody and T cell responses in order to protect against infections. Important successes have been obtained in protecting individuals against many deleterious pathological situations after parenteral vaccination. However, one of the major limitations of the current vaccination strategies is the administration route that may not be optimal for the induction of immunity at the site of pathogen entry, i.e., mucosal surfaces. It is now well documented that immune responses along the genital, respiratory, or gastrointestinal tracts have to be elicited locally to ensure efficient trafficking of effector and memory B and T cells to mucosal tissues. Moreover, needle-free mucosal delivery of vaccines is advantageous in terms of safety, compliance, and ease of administration. However, the quest for mucosal vaccines is challenging due to (1) the fact that Ag sampling has to be performed across the epithelium through a relatively limited number of portals of entry; (2) the deleterious acidic and proteolytic environment of the mucosae that affect the stability, integrity, and retention time of the applied Ags; and (3) the tolerogenic environment of mucosae, which requires the addition of adjuvants to elicit efficient effector immune responses. Until now, only few mucosally applicable vaccine formulations have been developed and successfully tested. In animal models and clinical trials, the use of lipidic structures such as liposomes, virosomes, immune stimulating complexes, gas-filled microbubbles and emulsions has proven efficient for the mucosal delivery of associated Ags and the induction of local and systemic immune reponses. Such particles are suitable for mucosal delivery because they protect the associated payload from degradation and deliver concentrated amounts of Ags via specialized sampling cells (microfold cells) within the mucosal epithelium to underlying antigen-presenting cells. The review aims at summarizing recent development in the field of mucosal vaccination using lipid-based particles. The modularity ensured by tailoring the lipidic design and content of particles, and their known safety as already established in humans, make the continuing appraisal of these vaccine candidates a promising development in the field of targeted mucosal vaccination.

A novel nanoemulsion vaccine induces mucosal Interleukin-17 responses and confers protection upon Mycobacterium tuberculosis challenge in mice

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb) is contracted via aerosol infection, typically affecting the lungs. Mycobacterium bovis bacillus Calmette-Guerin (BCG) is the only licensed vaccine and has variable efficacy in protecting against pulmonary TB. Additionally, chemotherapy is associated with low compliance contributing to development of multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mtb. Thus, there is an urgent need for the design of more effective vaccines against TB. Experimental vaccines delivered through the mucosal route induce robust T helper type 17 (Th17)/ Interleukin (IL) -17 responses and provide superior protection against Mtb infection. Thus, the development of safe mucosal adjuvants for human use is critical. In this study, we demonstrate that nanoemulsion (NE)-based adjuvants when delivered intranasally along with Mtb specific immunodominant antigens (NE-TB vaccine) induce potent mucosal IL-17T-cell responses. Additionally, the NE-TB vaccine confers significant protection against Mtb infection, and when delivered along with BCG, is associated with decreased disease severity. These findings strongly support the development of a NE-TB vaccine as a novel, safe and effective, first-of-kind IL-17 inducing mucosal vaccine for potential use in humans.

Plant-based vaccines for oral delivery of type 1 diabetes-related autoantigens: Evaluating oral tolerance mechanisms and disease prevention in NOD mice

Autoantigen-specific immunological tolerance represents a central objective for prevention of type 1 diabetes (T1D). Previous studies demonstrated mucosal antigen administration results in expansion of Foxp3+ and LAP+ regulatory T cells (Tregs), suggesting oral delivery of self-antigens might represent an effective means for modulating autoimmune disease. Early preclinical experiments using the non-obese diabetic (NOD) mouse model reported mucosal administration of T1D-related autoantigens [proinsulin or glutamic acid decarboxylase 65 (GAD)] delayed T1D onset, but published data are conflicting regarding dose, treatment duration, requirement for combinatorial agents, and extent of efficacy. Recently, dogma was challenged in a report demonstrating oral insulin does not prevent T1D in NOD mice, possibly due to antigen digestion prior to mucosal immune exposure. We used transplastomic plants expressing proinsulin and GAD to protect the autoantigens from degradation in an oral vaccine and tested the optimal combination, dose, and treatment duration for the prevention of T1D in NOD mice. Our data suggest oral autoantigen therapy alone does not effectively influence disease incidence or result in antigen-specific tolerance assessed by IL-10 measurement and Treg frequency. A more aggressive approach involving tolerogenic cytokine administration and/or lymphocyte depletion prior to oral antigen-specific immunotherapy will likely be required to impart durable therapeutic efficacy.

Modified Nanoemulsions with Iron Oxide for Magnetic Resonance Imaging

A nanoemulsion (NE) is a surfactant-based, oil-in-water, nanoscale, high-energy emulsion with a mean droplet diameter of 400–600 nm. When mixed with antigen and applied nasally, a NE acts as a mucosal adjuvant and induces mucosal immune responses. One possible mechanism for the adjuvant effect of this material is that it augments antigen uptake and distribution to lymphoid tissues, where the immune response is generated. Biocompatible iron oxide nanoparticles have been used as a unique imaging approach to study the dynamics of cells or molecular migration. To study the uptake of NEs and track them in vivo, iron oxide nanoparticles were synthesized and dispersed in soybean oil to make iron oxide-modified NEs. Our results show that iron oxide nanoparticles can be stabilized in the oil phase of the nanoemulsion at a concentration of 30 µg/μL and the iron oxide-modified NEs have a mean diameter of 521 nm. In vitro experiments demonstrated that iron oxide-modified NEs can affect uptake by TC-1 cells (a murine epithelial cell line) and reduce the intensity of magnetic resonance (MR) images by shortening the T2 time. Most importantly, in vivo studies demonstrated that iron oxide-modified NE could be detected in mouse nasal septum by both transmission electron microscopy and MR imaging. Altogether these experiments demonstrate that iron oxide-modified NE is a unique tool that can be used to study uptake and distribution of NEs after nasal application.

Intranasal nanoemulsion-based inactivated respiratory syncytial virus vaccines protect against viral challenge in cotton rats

Respiratory Syncytial Virus is a leading cause of bronchiolitis and pneumonia in infants, the elderly and individuals with compromised immune systems. Despite decades of research, there is currently no available vaccine for RSV. Our group has previously demonstrated that intranasal immunization of mice with RSV inactivated by and adjuvanted with W805EC nanoemulsion elicits robust humoral and cellular immune responses, resulting in protection against RSV infection. This protection was achieved without the induction of airway hyper-reactivity or a Th2-skewed immune response. The cotton rat Sigmodon hispidus has been used for years as an excellent small animal model of RSV disease. Thus, we extended these rodent studies to the more permissive cotton rat model. Intranasal immunization of the nanoemulsion-adjuvanted RSV vaccines induced high antibody titers and a robust Th1-skewed cellular response. Importantly, vaccination provided sterilizing cross-protective immunity against a heterologous RSV challenge and did not induce marked or severe histological effects or eosinophilia in the lung after viral challenge. Overall, these data demonstrate that nanoemulsion-formulated whole RSV vaccines are both safe and effective for immunization in multiple animal models.

Formulation of the respiratory syncytial virus fusion protein with a polymer-based combination adjuvant promotes transient and local innate immune responses and leads to improved adaptive immunity

Respiratory syncytial virus (RSV) causes serious upper and lower respiratory tract infections in newborns and infants. Presently, there is no licensed vaccine against RSV. We previously reported the safety and efficacy of a novel vaccine candidate (ΔF/TriAdj) in rodent and lamb models following intranasal immunization. However, the effects of the vaccine on the innate immune system in the upper and lower respiratory tracts, when delivered intranasally, have not been characterized. In the present study, we found that ΔF/TriAdj triggered transient production of chemokines, cytokines and interferons in the nasal tissues and lungs of BALB/c mice. The types of chemokines produced were consistent with the populations of immune cells recruited, i.e. dendritic cells, macrophages and neutrophils, in the nose-associated lymphoid tissue (NALT), lung and their draining lymph nodes of the ΔF/TriAdj-immunized group. In addition, ΔF/TriAdj stimulated cellular activation with generation of mucosal and systemic antibody responses, and conferred complete protection from viral infection in the lungs upon RSV challenge. The effect of ΔF/TriAdj was short-lived in the nasal tissues and more prolonged in the lungs. In addition, both innate and adaptive immune responses were lower when mice were immunized with ΔF alone. These results suggest that ΔF/TriAdj modulates the innate mucosal environment in both upper and lower respiratory tracts, which contributes to robust adaptive immune responses and long-term protective efficacy of this novel vaccine formulation.

Immunomodulation of TH2 biased immunity with mucosal administration of nanoemulsion adjuvant

TH2-biased immune responses are associated with inadequate protection against some pathogens and with cancer, colitis, asthma and allergy. Since most currently used vaccine adjuvants induce a TH2-biased response, this has led to interest in developing adjuvants capable of activating TH1 immunity and modulating existing TH2 responses. Immunotherapies to shift immune responses from TH2 to TH1 have generally required prolonged immunization protocols and have not induced effective TH1 responses. We have demonstrated that nanoscale emulsions (NE), a novel mucosal adjuvant, induce robust IgA and IgG antibody responses and TH1/TH17 cellular immunity resulting in protection against a variety of respiratory and mucosal infections. Because intranasal (i.n.) delivery of NE adjuvant consistently induces TH1/TH17 biased responses, we hypothesized that NE could be used as a therapeutic vaccine to redirect existing TH2 polarized immunity towards a more balanced TH1/TH2 profile. To test this, a TH2 immune response was established by intramuscular immunization of mice with alum-adjuvanted hepatitis B surface antigen (HBs), followed by a single subsequent i.n. immunization with NE-HBs. These animals exhibited increased TH1 associated immune responses and IL-17, and decreased TH2 cytokines (IL-4 and IL-5) and IgG1. NE immunization induced regulatory T cells and IL-10, and IL-10 was required for the suppression of TH2 immunity. These data demonstrate that NE-based vaccines can modulate existing TH2 immune responses to promote TH1/TH17 immunity and suggest the potential therapeutic use of NE vaccines for diseases associated with TH2 immunity.

Induction of systemic and mucosal immunity against methicillin-resistant Staphylococcus aureus infection by a novel nanoemulsion adjuvant vaccine

The Gram-positive bacterial pathogen methicillin-resistant Staphylococcus aureus (MRSA) can cause infections in the bloodstream, endocardial tissue, respiratory tract, culture-confirmed skin, or soft tissue. There are currently no effective vaccines, and none are expected to become available in the near future. An effective vaccine capable of eliciting both systemic and mucosal immune responses is also urgently needed. Here, we reported a novel oil-in-water nanoemulsion adjuvant vaccine containing an MRSA recombination protein antigen, Cremophor EL-35^® as a surfactant, and propylene glycol as a co-surfactant. This nanoemulsion vaccine, whose average diameter was 31.34±0.49 nm, demonstrated good protein structure integrity, protein specificity, and good stability at room temperature for 1 year. The intramuscular systemic and nasal mucosal immune responses demonstrated that this nanoemulsion vaccine could improve the specific immune responses of immunoglobulin (Ig)G and related subclasses, such as IgG1, IgG2a, and IgG2b, as well as IgA, in the serum after Balb/c mice intramuscular immunization and C57 mice nasal immunization. Furthermore, this nanoemulsion vaccine also markedly enhanced the interferon-γ and interleukin-17A cytokine cell immune response, improved the survival ratio, and reduced bacterial colonization. Taken together, our results show that this novel nanoemulsion vaccine has great potential and is a robust generator of an effective intramuscular systemic and nasal mucosal immune response without the need for an additional adjuvant. Thus, the present study serves as a sound scientific foundation for future strategies in the development of this novel nanoemulsion adjuvant vaccine to enhance both the intramuscular systemic and nasal mucosal immune responses.

Formulation, high throughput in vitro screening and in vivo functional characterization of nanoemulsion-based intranasal vaccine adjuvants

Vaccine adjuvants have been reported to induce both mucosal and systemic immunity when applied to mucosal surfaces and this dual response appears important for protection against certain pathogens. Despite the potential advantages, however, no mucosal adjuvants are currently approved for human use. Evaluating compounds as mucosal adjuvants is a slow and costly process due to the need for lengthy animal immunogenicity studies. We have constructed a library of 112 intranasal adjuvant candidate formulations consisting of oil-in-water nanoemulsions that contain various cationic and nonionic surfactants. To facilitate adjuvant development we first evaluated this library in a series of high-throughput, in vitro assays for activities associated with innate and adaptive immune activation in vivo. These in vitro assays screened for the ability of the adjuvant to bind to mucin, induce cytotoxicity, facilitate antigen uptake in epithelial and dendritic cells, and activate cellular pathways. We then sought to determine how these parameters related to adjuvant activity in vivo. While the in vitro assays alone were not enough to predict the in vivo adjuvant activity completely, several interesting relationships were found with immune responses in mice. Furthermore, by varying the physicochemical properties of the surfactant components (charge, surfactant polar head size and hydrophobicity) and the surfactant blend ratio of the formulations, the strength and type of the immune response generated (T_H1, T_H2, T_H17) could be modulated. These findings suggest the possibility of using high-throughput screens to aid in the design of custom adjuvants with unique immunological profiles to match specific mucosal vaccine applications.

Nanoemulsion-based mucosal adjuvant induces apoptosis in human epithelial cells

Nanoemulsions (NEs) are adjuvants that enhance antigen penetration of the nasal mucosa, increase cellular uptake of antigens by both epithelial and dendritic cells, and promote the migration of antigen-loaded dendritic cells to regional lymph nodes within 24-h of vaccine administration. The objective of this study was to elucidate cell death caused by W805EC NE and identify caspases and genes associated with death pathways. Consistent with this aim, we show that exposure of human epithelial cells (EC), both RPMI 2650 and FaDu, to NE results in the activation of caspases (1, 3/7, 6, 8, and 9) and the expression of genes involved in apoptotic as well as authophagy and necrosis pathways. Interestingly, the NE activates caspase 8 which promotes "immunogenic apoptosis". The rescue assay was employed to investigate the fate of RPMI 2650 cells treated with W805EC NE. After four-hour treatment with as little as 0.03% of NE no cells were rescued at 72h. Remarkably, immediately after four-hour treatment, the cells morphologically resembled untreated cells and most of the cells were alive. Altogether, these results suggest that NE induces death of human ECs through multiple pathways. Epithelial cell death caused by W805EC may have further implications on antigen uptake, processing, and presentation by DC's.

Adjuvants in the Driver's Seat: How Magnitude, Type, Fine Specificity and Longevity of Immune Responses Are Driven by Distinct Classes of Immune Potentiators

The mechanism by which vaccine adjuvants enhance immune responses has historically been considered to be the creation of an antigen depot. From here, the antigen is slowly released and provided to immune cells over an extended period of time. This "depot" was formed by associating the antigen with substances able to persist at the injection site, such as aluminum salts or emulsions. The identification of Pathogen-Associated Molecular Patterns (PAMPs) has greatly advanced our understanding of how adjuvants work beyond the simple concept of extended antigen release and has accelerated the development of novel adjuvants. This review focuses on the mode of action of different adjuvant classes in regards to the stimulation of specific immune cell subsets, the biasing of immune responses towards cellular or humoral immune response, the ability to mediate epitope spreading and the induction of persistent immunological memory. A better understanding of how particular adjuvants mediate their biological effects will eventually allow them to be selected for specific vaccines in a targeted and rational manner.

Distinct pathways of humoral and cellular immunity induced with the mucosal administration of a nanoemulsion adjuvant

Nasal administration of an oil-in-water nanoemulsion (NE) adjuvant W805EC produces potent systemic and mucosal, Th-1- and Th-17-balanced cellular responses. However, its molecular mechanism of action has not been fully characterized and is of particular interest because NE does not contain specific ligands for innate immune receptors. In these studies, we demonstrate that W805EC NE adjuvant activates innate immunity, induces specific gene transcription, and modulates NF-κB activity via TLR2 and TLR4 by a mechanism that appears to be distinct from typical TLR agonists. Nasal immunization with NE-based vaccine showed that the TLR2, TLR4, and MyD88 pathways and IL-12 and IL-12Rβ1 expression are not required for an Ab response, but they are essential for the induction of balanced Th-1 polarization and Th-17 cellular immunity. NE adjuvant induces MHC class II, CD80, and CD86 costimulatory molecule expression and dendritic cell maturation. Further, upon immunization with NE, adjuvant mice deficient in the CD86 receptor had normal Ab responses but significantly reduced Th-1 cellular responses, whereas animals deficient in both CD80 and CD86 or lacking CD40 failed to produce either humoral or cellular immunity. Overall, our data show that intranasal administration of Ag with NE induces TLR2 and TLR4 activation along with a MyD88-independent Ab response and a MyD88-dependent Th-1 and Th-17 cell-mediated immune response. These findings suggest that the unique properties of NE adjuvant may offer novel opportunities for understanding previously unrecognized mechanisms of immune activation important for generating effective mucosal and systemic immune responses.

Formulation and characterization of nanoemulsion intranasal adjuvants: effects of surfactant composition on mucoadhesion and immunogenicity

The development of effective intranasal vaccines is of great interest due to their potential to induce both mucosal and systemic immunity. Here we produced oil-in-water nanoemulsion (NE) formulations containing various cationic and nonionic surfactants for use as adjuvants for the intranasal delivery of vaccine antigens. NE induced immunogenicity and antigen delivery are believed to be facilitated through initial contact interactions between the NE droplet and mucosal surfaces which promote prolonged residence of the vaccine at the site of application, and thus cellular uptake. However, the details of this mechanism have yet to be fully characterized experimentally. We have studied the physicochemical properties of the NE droplet surfactant components and demonstrate that properties such as charge and polar headgroup geometry influence the association of the adjuvant with the mucus protein, mucin. Association of NE droplets with mucin in vitro was characterized by various biophysical and imaging methods including dynamic light scattering (DLS), zeta potential (ZP), and surface plasmon resonance (SPR) measurements as well as transmission electron microscopy (TEM). Emulsion surfactant compositions were varied in a systematic manner to evaluate the effects of hydrophobicity and polar group charge/size on the NE-mucin interaction. Several cationic NE formulations were found to facilitate cellular uptake of the model antigen, ovalbumin (OVA), in a nasal epithelial cell line. Furthermore, fluorescent images of tissue sections from mice intranasally immunized with the same NEs containing green fluorescent protein (GFP) antigen demonstrated that these NEs also enhanced mucosal layer penetration and cellular uptake of antigen in vivo. NE-mucin interactions observed through biophysical measurements corresponded with the ability of the NE to enhance cellular uptake. Formulations that enhanced antigen uptake in vitro and in vivo also led to the induction of a more consistent antigen specific immune response in mice immunized with NEs containing OVA, linking NE-facilitated mucosal layer penetration and cellular uptake to enhancement of the immune response. These findings suggest that biophysical measurement of the mucoadhesive properties of emulsion based vaccines constitutes an effective in vitro strategy for selecting NE candidates for further evaluation in vivo as mucosal adjuvants.

Intranasal immunization with W 80 5EC adjuvanted recombinant RSV rF-ptn enhances clearance of respiratory syncytial virus in a mouse model

Respiratory Syncytial Virus (RSV) is a ubiquitous virus that infects almost all people by age two and is a major source of respiratory illness in infants, the elderly and others with compromised immune systems. Currently there is no available vaccine. Prior efforts using formalin-inactivated RSV (FI-RSV) were associated with enhanced respiratory disease upon viral exposure following clinical vaccine trials. Several researchers and pharmaceutical companies have utilized vector-associated live attenuated RSV vaccines in pre-clinical and clinical studies. Another attractive approach, however, is a subunit vaccine which would be easier to produce and quality control. Our group has previously demonstrated in a murine model of infection that intranasal immunization with nanoemulsion-inactivated and adjuvanted RSV induces humoral and cellular immune responses, resulting in protection against RSV infection. The present studies characterize the immune responses elicited by intranasal RSV F protein adjuvanted with nanoemulsion. Intranasal application of nanoemulsion adjuvanted F protein induced a rapid and robust systemic and mucosal antibody response, as well as protection against subsequent RSV challenge. Importantly, RSV challenge in immunized animals did not elicit airway hyper-reactivity, a Th2-skewed immune response or immunopathology associated with hypersensitivity reactions with formalin-inactivated vaccine. These results suggest that RSV F protein adjuvanted with nanoemulsion may be a good mucosal vaccine candidate. Formulating RSV F protein in nanoemulsion creates a well-defined and well-controlled vaccine that can be delivered intranasally to induce T cell mediated immunity without inducing enhanced disease associated with the mouse model of FI-RSV vaccination and infection.

Applications of nanotechnology for immunology

Nanotechnology uses the unique properties of objects that function as a unit within the overall size range of 1-1,000 nanometres. The engineering of nanostructure materials, including nanoparticles, nanoemulsions or nanotubules, holds great promise for the development of new immunomodulatory agents, as such nanostructures can be used to more effectively manipulate or deliver immunologically active components to target sites. Successful applications of nanotechnology in the field of immunology will enable new generations of vaccines, adjuvants and immunomodulatory drugs that aim to improve clinical outcomes in response to a range of infectious and non-infectious diseases.

DNA-Encoded Flagellin Activates Toll-Like Receptor 5 (TLR5), Nod-like Receptor Family CARD Domain-Containing Protein 4 (NRLC4), and Acts as an Epidermal, Systemic, and Mucosal-Adjuvant

Eliciting effective immune responses using non-living/replicating DNA vaccines is a significant challenge. We have previously shown that ballistic dermal plasmid DNA-encoded flagellin (FliC) promotes humoral as well as cellular immunity to co-delivered antigens. Here, we observe that a plasmid encoding secreted FliC (pFliC(-gly)) produces flagellin capable of activating two innate immune receptors known to detect flagellin; Toll-like Receptor 5 (TLR5) and Nod-like Receptor family CARD domain-containing protein 4 (NRLC4). To test the ability of pFliC(-gly) to act as an adjuvant we immunized mice with plasmid encoding secreted FliC (pFliC(-gly)) and plasmid encoding a model antigen (ovalbumin) by three different immunization routes representative of dermal, systemic, and mucosal tissues. By all three routes we observed increases in antigen-specific antibodies in serum as well as MHC Class I-dependent cellular immune responses when pFliC(-gly) adjuvant was added. Additionally, we were able to induce mucosal antibody responses and Class II-dependent cellular immune responses after mucosal vaccination with pFliC(-gly). Humoral immune responses elicited by heterologus prime-boost immunization with a plasmid encoding HIV-1 from gp160 followed by protein boosting could be enhanced by use of pFliC(-gly). We also observed enhancement of cross-clade reactive IgA as well as a broadening of B cell epitope reactivity. These observations indicate that plasmid-encoded secreted flagellin can activate multiple innate immune responses and function as an adjuvant to non-living/replicating DNA immunizations. Moreover, the capacity to elicit mucosal immune responses, in addition to dermal and systemic properties, demonstrates the potential of flagellin to be used with vaccines designed to be delivered by various routes.

Nanoemulsion nasal adjuvant W₈₀5EC induces dendritic cell engulfment of antigen-primed epithelial cells

Nanoemulsions are adjuvants that enhance antigen penetration in the nasal mucosa, increase cellular uptake of antigens by both epithelial dendritic cells, and promote migration of antigen-loaded dendritic cells to regional lymph nodes within a day of vaccine administration. The objective of this study was to determine whether the W(80)5EC nanoemulsion adjuvant enhances immune response not only by direct uptake of antigen by dendritic cells, but also indirectly, by phagocytosis of antigen-primed, apoptotic, epithelial cells. Consistent with this, we show that exposure of both epithelial cells (TC-1s) and dendritic cells (JAWS II or bone marrow derived dendritic cells (BMDCs)) to nanoemulsion exhibited augmented antigen uptake in cell culture. TC-1 cells subsequently underwent G(2)/M cell cycle arrest and apoptosis, and when co-cultured with JAWS II or BMDCs were rapidly engulfed by the dendritic cells, which responded by up-regulating dendritic cell maturation marker CD86. Altogether these results suggest that the effectiveness of nanoemulsions as adjuvants stems, at least in part, from the engulfment of antigen-loaded epithelial cells, leading to enhanced antigen processing and a strong and balanced mucosal and systemic immune response.