Potential of nanoparticles for allergen-specific immunotherapy - use of silica nanoparticles as vaccination platform

Vaccination with Mincle agonist UM-1098 and mycobacterial antigens induces protective Th1 and Th17 responses

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is one of the top infectious killers in the world. The only licensed vaccine against TB, Bacille Calmette-Guérin (BCG), provides variable protection against pulmonary TB, especially in adults. Hence, novel TB vaccine approaches are urgently needed. Both Th1 and Th17 responses are necessary for protection against TB, yet effective adjuvants and vaccine delivery systems for inducing robust Th1 and Th17 immunity are lacking. Herein we describe a synthetic Mincle agonist, UM-1098, and a silica nanoparticle delivery system that drives Th1/Th17 responses to Mtb antigens. Stimulation of human peripheral blood mononuclear cells (hPBMCs) with UM-1098 induced high levels of Th17 polarizing cytokines IL-6, IL-1β, IL-23 as well as IL-12p70, IL-4 and TNF-α in vitro. PBMCs from both C57BL/6 and BALB/c mice responded with a similar cytokine pattern in vitro and in vivo. Importantly, intramuscular (I.M.) vaccination with UM-1098-adjuvanted TB antigen M72 resulted in significantly higher antigen-specific IFN-γ and IL-17A levels in C57BL/6 wt mice than Mincle KO mice. Vaccination of C57BL/6 wt mice with immunodominant Mtb antigens ESAT6/Ag85B or M72 resulted in predominantly Th1 and Th17 responses and induced antigen-specific serum antibodies. Notably, in a virulent Mtb challenge model, vaccination with UM-1098 adjuvanted ESAT6/Ag85B or M72 significantly reduced lung bacterial burden when compared with unvaccinated mice and protection occurred in the absence of pulmonary inflammation. These data demonstrate that the synthetic Mincle agonist UM-1098 induces strong Th1 and Th17 immunity after vaccination with Mtb antigens and provides protection against Mtb infection in mice.

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

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

New Therapeutic Approaches for Allergy: A Review of Cell Therapy and Bio- or Nano-Material-Based Strategies

Allergy constitutes a major health issue due to its large prevalence. The established therapeutic approaches (allergen avoidance, antihistamines, and corticosteroids) do not address the underlying causes of the pathology, highlighting the need for other long-term treatment options. Antigen-specific immunotherapy enables the long-term control of allergic diseases by promoting immunological tolerance to the allergen. However, efficacious immunotherapies are not available for all possible allergens, and the risk of undesired reactions during therapy remains a concern, especially in patients with severe allergic reactions. In this context, two types of therapeutic strategies appear especially promising for the future in the context of allergy: cell therapy and bio- or nano-material-based therapy. In this review, the main strategies developed this far in these two types of strategies are discussed, with several examples illustrating the different approaches.

Interfacial behavior of polar and nonpolar frozen/unfrozen liquids interacting with hydrophilic and hydrophobic nanosilicas alone and in blends

HYPOTHESIS

Various nanosilica characteristics depend on hydrophobization strongly affecting interfacial phenomena. Is it possible to prepare hydrophilic samples with hydrophobic silica (AM1) alone and in blends with hydrophilic one (A-300)? It can be done with addition of a small amount of water to the powders which then are mechanically treated.

EXPERIMENTS

Nanosilicas were characterized using adsorption, desorption, microscopic, spectroscopic, and quantum chemistry methods. ¹H NMR spectroscopy and cryoporometry were applied to AM1 and AM1/A-300 blends wetted and mechanically treated. Wetted blends were studied with additions of n-decane and chloroform-d.

FINDINGS

The powders wetted at h = 0.3-3.0 g of water per gram of dry solids have increased bulk density. Samples are in gel-like state at h = 4-5 g/g. Water interaction energy with nanoparticles nonmonotonically depends on h (maximal at h = 3 g/g). Upon mechanical treatment of wetted blends (h < 1.5 g/g), separated AM1 structures are absent. At greater h values, blend reorganization occurs to form AM1 aggregates covered by A-300 shells. Organics can displace water from mesovoids toward narrower pores inaccessible for larger molecules or into larger voids to reduce the contact area between immiscible liquids. Freezing point depression caused by confined space and dissolution effects is affected by the blend organization.

Formulations for Allergen Immunotherapy in Human and Veterinary Patients: New Candidates on the Horizon

Allergen immunotherapy is currently the only causal treatment for allergic diseases in human beings and animals. It aims to re-direct the immune system into a tolerogenic or desensitized state. Requirements include clinical efficacy, safety, and schedules optimizing patient or owner compliance. To achieve these goals, specific allergens can be formulated with adjuvants that prolong tissue deposition and support uptake by antigen presenting cells, and/or provide a beneficial immunomodulatory action. Here, we depict adjuvant formulations being investigated for human and veterinary allergen immunotherapy.

Nanotechnology-Based Vaccines for Allergen-Specific Immunotherapy: Potentials and Challenges of Conventional and Novel Adjuvants under Research

The increasing prevalence of allergic diseases demands efficient therapeutic strategies for their mitigation. Allergen-specific immunotherapy (AIT) is the only causal rather than symptomatic treatment method available for allergy. Currently, AIT is being administered using immune response modifiers or adjuvants. Adjuvants aid in the induction of a vigorous and long-lasting immune response, thereby improving the efficiency of AIT. The successful development of a novel adjuvant requires a thorough understanding of the conventional and novel adjuvants under development. Thus, this review discusses the potentials and challenges of these adjuvants and their mechanism of action. Vaccine development based on nanoparticles is a promising strategy for AIT, due to their inherent physicochemical properties, along with their ease of production and ability to stimulate innate immunity. Although nanoparticles have provided promising results as an adjuvant for AIT in in vivo studies, a deeper insight into the interaction of nanoparticle-allergen complexes with the immune system is necessary. This review focuses on the methods of harnessing the adjuvant effect of nanoparticles by detailing the molecular mechanisms underlying the immune response, which includes allergen uptake, processing, presentation, and induction of T cell differentiation.

Molecular characterization of B-cell epitopes for the major fish allergen, parvalbumin, by shotgun proteomics, protein-based bioinformatics and IgE-reactive approaches

Parvalbumins beta (β-PRVBs) are the main fish allergens. The only proven and effective treatment for this type of hypersensitivity is to consume a diet free of fish. We present the molecular characterization of B-cell epitopes by shotgun proteomics of different β-PRVBs combined with protein-based bioinformatics and IgE-reactive approaches. The final goal of this work is to identify potential peptide vaccine candidates for fish allergy. Purified β-PRVBs from the main fifteen different fish species that cause allergy were analyzed by shotgun proteomics. Identified β-PRVBs peptide sequences and ninety-eight β-PRVB protein sequences from UniProtKB were combined, aligned and analyzed to determine B-cell epitopes using the Kolaskar and Tongaonkar algorithm. The highest rated predicted B-cell peptide epitopes were evaluated by ELISA using the corresponding synthetic peptides and sera from healthy and fish allergic patients. A total of 35 peptides were identified as B-cell epitopes. The top B-cell peptide epitopes (LKLFLQV, ACAHLCK, FAVLVKQ and LFLQNFV) that may induce protective immune responses were selected as potential peptide vaccine candidates. The 3D model of these peptides were located in the surface of the protein. This study provides the global characterization of B-cell epitopes for all β-PRVBs sequences that will facilitate the design of new potential immunotherapies. SIGNIFICANCE: This work provides the global characterization of B-cell epitopes for all β-PRVBs sequences by Shotgun Proteomics combined with Protein-based Bioinformatics and IgE-reactive approaches. This study will increase our understanding of the molecular mechanisms whereby fish allergens elicit allergic reactions and will facilitate the design of new potential peptide vaccine candidates.

Amorphous silicon dioxide nanoparticles modulate immune responses in a model of allergic contact dermatitis

Amorphous silicon dioxide nanoparticles (SiNPs) are ubiquitous, and they are currently found in cosmetics, drugs, and foods. Biomedical research is also focused on using these nanoparticles as drug delivery and bio-sensing platforms. Due to the high potential for skin exposure to SiNPs, research into the effect of topical exposure on both healthy and inflammatory skin models is warranted. While we observe only minimal effects of SiNPs on healthy mouse skin, there is an immunomodulatory effect of these NPs in a model of allergic contact dermatitis. The effect appears to be mediated partly by keratinocytes and results in decreases in epidermal hyperplasia, inflammatory cytokine release, immune cell infiltration, and a subsequent reduction in skin swelling. Additional research is required to further our mechanistic understanding and to validate the extent of this immunomodulatory effect in human subjects in order to assess the potential prophylactic use of SiNPs for treating allergic skin conditions.

A Concentration-Dependent Insulin Immobilization Behavior of Alkyl-Modified Silica Vesicles: The Impact of Alkyl Chain Length

The insulin immobilization behaviors of silica vesicles (SV) before and after modification with hydrophobic alkyl -C₈ and -C₁₈ groups have been studied and correlated to the grafted alkyl chain length. In order to minimize the influence from the other structural parameters, monolayered -C₈ or -C₁₈ groups are grafted onto SV with controlled density. The insulin immobilization capacity of SV is dependent on the initial insulin concentrations (IIC). At high IIC (2.6-3.0 mg/mL), the trend of insulin immobilization capacity of SV is SV-OH > SV-C₈ > SV-C₁₈, which is determined mainly by the surface area of SV. At medium IIC (0.6-1.9 mg/mL), the trend changes to SV-C₈ ≥ SV-C₁₈ > SV-OH as both the surface area and alkyl chain length contribute to the insulin immobilization. At an extremely low IIC, the hydrophobic-hydrophobic interaction between the alkyl group and insulin molecules plays the most significant role. Consequently, SV-C₁₈ with longer alkyl groups and the highest hydrophobicity show the best insulin enrichment performance compared to SV-C₈ and SV-OH, as evidenced by an insulin detection limit of 0.001 ng/mL in phosphate buffered saline (PBS) and 0.05 ng/mL in artficial urine determined by mass spectrometry (MS).

Nanomaterials in the Context of Type 2 Immune Responses-Fears and Potentials

The type 2 immune response is an adaptive immune program involved in defense against parasites, detoxification, and wound healing, but is predominantly known for its pathophysiological effects, manifesting as allergic disease. Engineered nanoparticles (NPs) are non-self entities that, to our knowledge, do not stimulate detrimental type 2 responses directly, but have the potential to modulate ongoing reactions in various ways, including the delivery of substances aiming at providing a therapeutic benefit. We review, here, the state of knowledge concerning the interaction of NPs with type 2 immune responses and highlight their potential as a multifunctional platform for therapeutic intervention.