Protective efficiency of dendrosomes as novel nano-sized adjuvants for DNA vaccination against birch pollen allergy

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.

Current possibilities and future perspectives for improving efficacy of allergen-specific sublingual immunotherapy

Allergen-specific sublingual immunotherapy (SLIT), a safe and efficient route for treating type I hypersensitivity disorders, requires high doses of allergens. SLIT is generally performed without adjuvants and delivery systems. Therefore, allergen formulation with appropriate presentation platforms results in improved allergen availability, targeting the immune cells, inducing regulatory immune responses, and enhancing immunotherapy's efficacy while decreasing the dose of the allergen. In this review, we discuss the adjuvants and delivery systems that have been applied as allergen-presentation platforms for SLIT. These adjuvants include TLRs ligands, 1α, 25-dihydroxy vitamin D3, galectin-9, probiotic and bacterial components that provoke allergen-specific helper type-1 T lymphocytes (TH1), and regulatory T cells (Tregs). Another approach is encapsulation or adsorption of the allergens into a particulate vector system to facilitate allergen capture by tolerogenic dendritic cells. Also, we proposed strategies to increasing the efficacy of SLIT via new immunopotentiators and carrier systems in the future.

Role of nanostructures in allergy: Diagnostics, treatments and safety

Nanotechnology is science, engineering and technology conducted at the nanoscale, which is about 1-100 nm. It has led to the development of nanomaterials, which behave very differently from materials with larger scales and can have a wide range of applications in biomedicine. The physical and chemical properties of materials of such small compounds depend mainly on the size, shape, composition and functionalization of the system. Nanoparticles, carbon nanotubes, liposomes, polymers, dendrimers and nanogels, among others, can be nanoengineeried for controlling all parameters, including their functionalization with ligands, which provide the desired interaction with the immunological system, that is dendritic cell receptors to activate and/or modulate the response, as well as specific IgE, or effector cell receptors. However, undesired issues related to toxicity and hypersensitivity responses can also happen and would need evaluation. There are wide panels of accessible structures, and controlling their physico-chemical properties would permit obtaining safer and more efficient compounds for clinical applications goals, either in diagnosis or treatment. The application of dendrimeric antigens, nanoallergens and nanoparticles in allergy diagnosis is very promising since it can improve sensitivity by increasing specific IgE binding, mimicking carrier proteins or enhancing signal detection. Additionally, in the case of immunotherapy, glycodendrimers, liposomes, polymers and nanoparticles have shown interest, behaving as platforms of allergenic structures, adjuvants or protectors of allergen from degradation or having a depot capacity. Taken together, the application of nanotechnology to allergy shows promising facts facing important goals related to the improvement of diagnosis as well as specific immunotherapy.

Use of Engineered Nanoparticles (ENPs) for the Study of High-Affinity IgE FcεRI Receptor Engagement and Rat Basophilic Leukemia (RBL) Cell Degranulation

Degranulation of mast cells and basophils occurs after the cross-linking of FcεRI receptor-bound IgE by multivalent allergens, resulting in the release of a range of de novo synthesized and preformed mediators of the allergic response. β-Hexosaminidase release is usually measured as a simple readout for degranulation. Furthermore, the rat basophilic leukemia (RBL)-2H3 cell line is commonly used for measuring degranulation, monitoring β-hexosaminidase release. Here, we describe surface-engineered and modified nanoparticles with specific ligands in order to study the signaling and cellular responses of the RBL-2H3 cell line.

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.

Nanoparticle-based immunotherapy: state of the art and future perspectives

INTRODUCTION

For several years now, medicine has been benefiting from the contribution of nanoparticles (NPs) technology for both diagnosis and therapy. They can be used as adjuvants, being capable per se of immune-modulating activity, or as carriers for molecules to be transported to a specific target, eventually loaded with specific ligands favoring specific uptake.

AREAS COVERED

The review focuses on experimental use of NPs as adjuvants/carriers for allergen immunotherapy (AIT). Human clinical trials conducted so far are discussed.

EXPERT OPINION

Results of experimental studies and recent clinical trials support the use of NPs as carrier/adjuvant in AIT. Comparisons between NP-based and classical AIT are needed, to show the usefulness of the NP-based approach. However, there are still unsolved problems: the persistence of non-degradable NPs with possible toxicological consequences, and the formation of the protein corona around the NPs, which could alter their activity and fate. Virus-like particles seem the most promising NPs for allergy treatment, as for other vaccines. Over the next decade, NP-based AIT will be largely used to treat allergic disorders.

Assessment of interactions of efavirenz solid drug nanoparticles with human immunological and haematological systems

Background

Recent work has developed solid drug nanoparticles (SDNs) of efavirenz that have been demonstrated, preclinically, improved oral bioavailability and the potential to enable up to a 50% dose reduction, and is currently being studied in a healthy volunteer clinical trial. Other SDN formulations are being studied for parenteral administration, either as intramuscular long-acting formulations, or for direct administration intravenously. The interaction of nanoparticles with the immunological and haematological systems can be a major barrier to successful translation but has been understudied for SDN formulations. Here we have conducted a preclinical evaluation of efavirenz SDN to assess their potential interaction with these systems. Platelet aggregation and activation, plasma coagulation, haemolysis, complement activation, T cell functionality and phenotype, monocyte derived macrophage functionality, and NK cell function were assessed in primary healthy volunteer samples treated with either aqueous efavirenz or efavirenz SDN.

Results

Efavirenz SDNs were shown not to interfere with any of the systems studied in terms of immunostimulation nor immunosuppression. Although efavirenz aqueous solution was shown to cause significant haemolysis ex vivo, efavirenz SDNs did not. No other interaction with haematological systems was observed. Efavirenz SDNs have been demonstrated to be immunologically and haematologically inert in the utilised assays.

Conclusions

Taken collectively, along with the recent observation that lopinavir SDN formulations did not impact immunological responses, these data indicate that this type of nanoformulation does not elicit immunological consequences seen with other types of nanomaterial. The methodologies presented here provide a framework for pre-emptive preclinical characterisation of nanoparticle safety.

Electronic supplementary material

The online version of this article (10.1186/s12951-018-0349-y) contains supplementary material, which is available to authorized users.

Recent advances in the use of nanoparticles for allergen-specific immunotherapy

The number of patients suffering from allergic asthma and rhinoconjunctivitis has increased dramatically within the last decades. Allergen-specific immunotherapy (AIT) is the only available cause-oriented therapy so far. AIT reduces symptoms, but has also a disease-modifying effect. Disadvantages are a long-lasting procedure, and in a few cases potential systemic adverse reactions. Encapsulation of allergens or DNA vaccines into nanostructures may provide advantages compared to the conventional AIT with noncapsulated allergen extracts: The protein/DNA molecule can be protected from degradation, higher local concentrations and targeted delivery to the site of action appear possible, and most importantly, recognition of encapsulated allergen by the immune system, especially by IgE antibodies, is prevented. AIT with nanoparticles (NPs) may offer a safer and potentially more efficient way of treatment for allergic diseases. In this review, we summarize the use of biodegradable NPs consisting of synthetic or natural polymers, liposomes, and virus-like particles as well as nonbiodegradable NPs like dendrimers, and carbon- or metal-based NPs for AIT. More or less successful applications of these NPs in prophylactic as well as therapeutic vaccination approaches in rodents or other animals as well as first human clinical trials are discussed in detail.

Thiomers and their potential applications in drug delivery

INTRODUCTION

Thiomers are the product of the immobilization of sulfhydryl-bearing ligands onto the polymer backbone of a conventional polymer, which results in a significant improvement in mucoadhesion; in situ gelation and efflux inhibition compare with unchanged polymers. Because of thiol groups, thiomers have more reactivity and enhanced protection against oxidation. Since the late 1990s, extensive work has been conducted on these promising polymeric excipients in the pharmaceutical field. Areas covered: This review covers thiomers, their classification and their different properties. Various techniques for the synthesis, purification and characterization of thiomers are described in detail. This review also encompasses their various properties such as mucoadhesion, permeation enhancement, in situ gelation and efflux inhibition, as well as different formulations based on thiomers. In addition to the use of thiomers as multifunctional excipients, this review also encompasses their use as drugs. Expert opinion: The synthesis is realized by linkage of sulfhydryl-bearing ligands but reported methods give low yields. Higher degrees of modification are not necessary and would probably lead to extreme changes in properties. Nevertheless, an accurate characterization of the final product is important. The scale-up procedure for industrial manufacturing has been adapted to produce GMP materials; Lacrimera® eye drops have already entered the European market.

Current understanding of interactions between nanoparticles and the immune system

The delivery of drugs, antigens, and imaging agents benefits from using nanotechnology-based carriers. The successful translation of nanoformulations to the clinic involves thorough assessment of their safety profiles, which, among other end-points, includes evaluation of immunotoxicity. The past decade of research focusing on nanoparticle interaction with the immune system has been fruitful in terms of understanding the basics of nanoparticle immunocompatibility, developing a bioanalytical infrastructure to screen for nanoparticle-mediated immune reactions, beginning to uncover the mechanisms of nanoparticle immunotoxicity, and utilizing current knowledge about the structure-activity relationship between nanoparticles' physicochemical properties and their effects on the immune system to guide safe drug delivery. In the present review, we focus on the most prominent pieces of the nanoparticle-immune system puzzle and discuss the achievements, disappointments, and lessons learned over the past 15years of research on the immunotoxicity of engineered nanomaterials.

Determining the relationship between nanoparticle characteristics and immunotoxicity: key challenges and approaches

The growing wealth of information regarding the influence that physicochemical characteristics play on nanoparticle biocompatibility and safety is allowing improved design and rationale for their development and preclinical assessment. Accurate and appropriate measurement of these characteristics accompanied by informed toxicological assessment is a necessity for the development of safe and effective nanomedicines. While particle type, formulation and mode of administration dictate the individual causes for concern through development, the benefits of nanoformulation for treatment of the diseased state are great. Here we have proposed certain considerations and suggestions, which could lead to better-informed preclinical assessment of nanomaterials for nanomedicine, as well as how this information can and should be extrapolated to the physiological state of the end user.

Hypersensitivity and nanoparticles: update and research trends

Nanotechnology holds a great promise for a wide range of medical-intent applications (diagnostic, treatment and prophylaxis of various diseases). Their advantages are due to their size, versatility and potential for multiple simultaneous applications. However, concerns have been formulated by scientific world due to insufficient data on toxicity of nanomaterials. One area of interest is represented by the interactions between nanoparticles and the components of the immune system. We review herein reported data on hypersensitivity reactions. The role exerted by nanoparticles in both immunostimulation and immunosuppression in allergen-driven mechanisms was studied, as well as future trends in worldwide research.

Dendrosome mediated topical gene silencing by PLK-1 specific siRNA: implication in treatment of skin cancer in mouse model

Topical application of PLK-1 siRNA bearing dendrosomes on DMBA induced skin papillomas in mice exhibit potent anti-cancer effect. The treatment leads to reduced number and sizes of papillomas.

Enhancement of immunogenicity and efficacy of a plasmid DNA rabies vaccine by nanoformulation with a fourth-generation amine-terminated poly(ether imine) dendrimer

Purpose

Delayed onset of, and low magnitude of, protective immune responses are major drawbacks limiting the practical utility of plasmid vaccination against rabies. In this study we evaluated whether nanoformulation with the novel poly(ether imine) (PETIM) dendrimer can enhance the immunogenicity and efficacy of a plasmid-based rabies vaccine.

Materials and methods

A plasmid vaccine construct (pIRES-Rgp) was prepared by cloning the full-length rabies virus glycoprotein gene into pIRES vector. Drawing upon the results of our previous study, a dendriplex (dendrimer-DNA complex) of pIRES-Rgp was made with PETIM dendrimer (10:1 w/w, PETIM:pIRES-Rgp). In vitro transfection was done on baby hamster kidney (BHK)-21 cells to evaluate expression of glycoprotein gene from pIRES-Rgp and PETIM-pIRES-Rgp. Subsequently, groups of Swiss albino mice were immunized intramuscularly with pIRES-Rgp or PETIM-pIRES-Rgp. A commercially available cell culture rabies vaccine was included for comparison. Rabies virus neutralizing antibody (RVNA) titers in the immune sera were evaluated on days 14, 28, and 90 by rapid fluorescent focus inhibition test. Finally, an intracerebral challenge study using a challenge virus standard strain of rabies virus was done to evaluate the protective efficacy of the formulations.

Results

Protective levels of RVNA titer (≥0.5 IU/mL) were observed by day 14 in animals immunized with pIRES-Rgp and its dendriplex. Notably, PETIM-pIRES-Rgp produced 4.5-fold higher RVNA titers compared to pIRES-Rgp at this time point. All mice immunized with the PETIM-pIRES-Rgp survived the intracerebral rabies virus challenge, compared with 60% in the group which received pIRES-Rgp.

Conclusion

Our results suggest that nanoformulation with PETIM dendrimer can produce an earlier onset of a high-titered protective antibody response to a plasmid-based rabies vaccine. PETIM dendriplexing appears to be an efficacious nonviral delivery strategy to enhance genetic vaccination.

Testing the nanoparticle-allostatic cross-adaptation-sensitization model for homeopathic remedy effects

Key concepts of the Nanoparticle-Allostatic Cross-Adaptation-Sensitization (NPCAS) Model for the action of homeopathic remedies in living systems include source nanoparticles as low level environmental stressors, heterotypic hormesis, cross-adaptation, allostasis (stress response network), time-dependent sensitization with endogenous amplification and bidirectional change, and self-organizing complex adaptive systems. The model accommodates the requirement for measurable physical agents in the remedy (source nanoparticles and/or source adsorbed to silica nanoparticles). Hormetic adaptive responses in the organism, triggered by nanoparticles; bipolar, metaplastic change, dependent on the history of the organism. Clinical matching of the patient's symptom picture, including modalities, to the symptom pattern that the source material can cause (cross-adaptation and cross-sensitization). Evidence for nanoparticle-related quantum macro-entanglement in homeopathic pathogenetic trials. This paper examines research implications of the model, discussing the following hypotheses: Variability in nanoparticle size, morphology, and aggregation affects remedy properties and reproducibility of findings. Homeopathic remedies modulate adaptive allostatic responses, with multiple dynamic short- and long-term effects. Simillimum remedy nanoparticles, as novel mild stressors corresponding to the organism's dysfunction initiate time-dependent cross-sensitization, reversing the direction of dysfunctional reactivity to environmental stressors. The NPCAS model suggests a way forward for systematic research on homeopathy. The central proposition is that homeopathic treatment is a form of nanomedicine acting by modulation of endogenous adaptation and metaplastic amplification processes in the organism to enhance long-term systemic resilience and health.

Nanotechnological Approaches for Genetic Immunization

Genetic immunization is one of the important findings that provide multifaceted immunological response against infectious diseases. With the advent of r-DNA technology, it is possible to construct vector with immunologically active genes against specific pathogens. Nevertheless, site-specific delivery of constructed genetic material is an important contributory factor for eliciting specific cellular and humoral immune response. Nanotechnology has demonstrated immense potential for the site-specific delivery of biomolecules. Several polymeric and lipidic nanocarriers have been utilized for the delivery of genetic materials. These systems seem to have better compatibility, low toxicity, economical and capable to delivering biomolecules to intracellular site for the better expression of desired antigens. Further, surface engineering of nanocarriers and targeting approaches have an ability to offer better presentation of antigenic material to immunological cells. This chapter gives an overview of existing and emerging nanotechnological approaches for the delivery of genetic materials.

Thiomers: promising platform for macromolecular drug delivery

The application of macromolecules as therapeutic agents holds great promise for several major disorders such as cancer and cardiovascular disease. However, their use is limited by the lack of efficient, safe and specific delivery strategies. A promising strategy to overcome these challenges might be the use of thiolated polymers or designated thiomers. Thiomers are synthesized by immobilization of sulfhydryl bearing ligands on a polymeric backbone of well-established polymers. These multifunctional polymeric excipients show advantages in mucoadhesion, enzyme and efflux pump inhibition in comparison to unmodified polymers. One obstacle in the use of thiomers is that they are prone to oxidation at lower pH but this could be solved by introducing a completely new generation of thiomers, namely, the preactivated thiomer generation. Preactivated thiomers are mixed disulfides, which exhibit oxidation resistance and, beyond that, improved thiomer features. This review summarizes recent findings of polymeric excipients for macromolecular drug delivery as well as their synthesis and distinctive features.

Biocompatibility of engineered nanoparticles for drug delivery

The rapid advancement of nanotechnology has raised the possibility of using engineered nanoparticles that interact within biological environments for treatment of diseases. Nanoparticles interacting with cells and the extracellular environment can trigger a sequence of biological effects. These effects largely depend on the dynamic physicochemical characteristics of nanoparticles, which determine the biocompatibility and efficacy of the intended outcomes. Understanding the mechanisms behind these different outcomes will allow prediction of the relationship between nanostructures and their interactions with the biological milieu. At present, almost no standard biocompatibility evaluation criteria have been established, in particular for nanoparticles used in drug delivery systems. Therefore, an appropriate safety guideline of nanoparticles on human health with assessable endpoints is needed. In this review, we discuss the data existing in the literature regarding biocompatibility of nanoparticles for drug delivery applications. We also review the various types of nanoparticles used in drug delivery systems while addressing new challenges and research directions. Presenting the aforementioned information will aid in getting one step closer to formulating compatibility criteria for biological systems under exposure to different nanoparticles.

Biomedical nanoparticles modulate specific CD4+ T cell stimulation by inhibition of antigen processing in dendritic cells

Understanding how nanoparticles may affect immune responses is an essential prerequisite to developing novel clinical applications. To investigate nanoparticle-dependent outcomes on immune responses, dendritic cells (DCs) were treated with model biomedical poly(vinylalcohol)-coated super-paramagnetic iron oxide nanoparticles (PVA-SPIONs). PVA-SPIONs uptake by human monocyte-derived DCs (MDDCs) was analyzed by flow cytometry (FACS) and advanced imaging techniques. Viability, activation, function, and stimulatory capacity of MDDCs were assessed by FACS and an in vitro CD4+ T cell assay. PVA-SPION uptake was dose-dependent, decreased by lipopolysaccharide (LPS)-induced MDDC maturation at higher particle concentrations, and was inhibited by cytochalasin D pre-treatment. PVA-SPIONs did not alter surface marker expression (CD80, CD83, CD86, myeloid/plasmacytoid DC markers) or antigen-uptake, but decreased the capacity of MDDCs to process antigen, stimulate CD4+ T cells, and induce cytokines. The decreased antigen processing and CD4+ T cell stimulation capability of MDDCs following PVA-SPION treatment suggests that MDDCs may revert to a more functionally immature state following particle exposure.

Immunomodulatory nanoparticles as adjuvants and allergen-delivery system to human dendritic cells: Implications for specific immunotherapy

Novel adjuvants and antigen-delivery systems with immunomodulatory properties that shift the allergenic Th2 response towards a Th1 or regulatory T cell response are desired for allergen-specific immunotherapy. This study demonstrates that 200-nm sized biodegradable poly(gamma-glutamic acid) (gamma-PGA) nanoparticles (NPs) are activators of human monocyte-derived dendritic cells (MoDCs). Gamma-PGA NPs are efficiently internalized by immature MoDCs and strongly stimulate production of chemokines and inflammatory cytokines as well as up-regulation of co-stimulatory molecules and immunomodulatory mediators involved in efficient T cell priming. Furthermore, MoDCs from allergic subjects stimulated in vitro with a mixture of gamma-PGA NPs and extract of grass pollen allergen Phleum pratense (Phl p) augment allergen-specific IL-10 production and proliferation of autologous CD4(+) memory T cells. Thus, gamma-PGA NPs are promising as sophisticated adjuvants and allergen-delivery systems in allergen-specific immunotherapy.

WITHDRAWN: An investigation on the protective efficiency of recombinant ovalbumin and its mutants against anaphylaxis in mice

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Nanoparticles and the immune system

Today nanotechnology is finding growing applications in industry, biology, and medicine. The clear benefits of using nanosized products in various biological and medical applications are often challenged by concerns about the lack of adequate data regarding their toxicity. One area of interest involves the interactions between nanoparticles and the components of the immune system. Nanoparticles can be engineered to either avoid immune system recognition or specifically inhibit or enhance the immune responses. We review herein reported observations on nanoparticle-mediated immunostimulation and immunosuppression, focusing on possible theories regarding how manipulation of particle physicochemical properties can influence their interaction with immune cells to attain desirable immunomodulation and avoid undesirable immunotoxicity.

Immunological properties of engineered nanomaterials

Most research on the toxicology of nanomaterials has focused on the effects of nanoparticles that enter the body accidentally. There has been much less research on the toxicology of nanoparticles that are used for biomedical applications, such as drug delivery or imaging, in which the nanoparticles are deliberately placed in the body. Moreover, there are no harmonized standards for assessing the toxicity of nanoparticles to the immune system (immunotoxicity). Here we review recent research on immunotoxicity, along with data on a range of nanotechnology-based drugs that are at different stages in the approval process. Research shows that nanoparticles can stimulate and/or suppress the immune responses, and that their compatibility with the immune system is largely determined by their surface chemistry. Modifying these factors can significantly reduce the immunotoxicity of nanoparticles and make them useful platforms for drug delivery.

Thiomers: forms, functions and applications to nanomedicine

Thiolated polymers or designated thiomers are gained by immobilization of sulhydryl-bearing ligands on the polymeric backbone of well established polymers, such as chitosan and poly(acrylates). This functionalization leads to significantly improved properties compared with the corresponding unmodified polymers. Mucoadhesive properties are strongly improved by the formation of disulfide bonds between thiol groups of the thiomer and cysteine-rich glycoproteins of the mucus gel layer. Moreover, enzyme- and efflux-pump inhibiting, as well as significantly improved permeation-enhancing properties, are advantages of polymer thiolization. Thiomer micro- and nano-particlulate delivery systems can be generated via different techniques, such as in situ gelation and subsequent covalent crosslinking, radical emulsion polymerization, emulsification/solvent evaporation or air jet milling. As thiomer micro- and nano-particles were shown to exhibit the same features as thiolated polymers per se, they might be useful tools for the delivery of various types of challenging drugs.