Co-administration of non-carrier nanoparticles boosts antigen immune response without requiring protein conjugation

Current Trends and Prospects for Application of Green Synthesized Metal Nanoparticles in Cancer and COVID-19 Therapies

Cancer and COVID-19 have been deemed as world health concerns due to the millions of lives that they have claimed over the years. Extensive efforts have been made to develop sophisticated, site-specific, and safe strategies that can effectively diagnose, prevent, manage, and treat these diseases. These strategies involve the implementation of metal nanoparticles and metal oxides such as gold, silver, iron oxide, titanium oxide, zinc oxide, and copper oxide, formulated through nanotechnology as alternative anticancer or antiviral therapeutics or drug delivery systems. This review provides a perspective on metal nanoparticles and their potential application in cancer and COVID-19 treatments. The data of published studies were critically analysed to expose the potential therapeutic relevance of green synthesized metal nanoparticles in cancer and COVID-19. Although various research reports highlight the great potential of metal and metal oxide nanoparticles as alternative nanotherapeutics, issues of nanotoxicity, complex methods of preparation, biodegradability, and clearance are lingering challenges for the successful clinical application of the NPs. Thus, future innovations include fabricating metal nanoparticles with eco-friendly materials, tailor making them with optimal therapeutics for specific disease targeting, and in vitro and in vivo evaluation of safety, therapeutic efficiency, pharmacokinetics, and biodistribution.

Exosome-based delivery of VP1 protein conferred enhanced resistance of mice to CVB3-induced viral myocarditis

Coxsackievirus B3 (CVB3) is an important cause of viral myocarditis with no vaccine available in clinic. Herein we constructed an exosome-based anti-CVB3 vaccine (Exo-VP1), and compared its immunogenicity and immunoprotection with our previously reported recombinant VP1 protein (rVP1) vaccine. We found that compared with the 25 μg rVP1 vaccine, Exo-VP1 vaccine containing only 2 μg VP1 protein induced much stronger CVB3-specific T cell proliferation and CTL responses (with an increase of more than 70% and 40% respectively), and elicited greater splenic Th1/CTL associated cytokines (IFN-γ, TNF-α and IL-12). Furthermore, higher IgG levels with increased neutralizing titers and avidity were also evidenced in Exo-VP1 group. Consistently, Exo-VP1 group exhibited enhanced resistance to viral myocarditis than rVP1 vaccine, reflected by reduced cardiac viral loads, improved myocardial inflammation and an increased survival rate. Collectively, we reported that Exo-VP1 might present a more potent CVB3 vaccine candidate than rVP1 vaccine.

Engineered Hydroxyapatite Nanoadjuvants with Controlled Shape and Aspect Ratios Reveal Their Immunomodulatory Potentials

Hydroxyapatite (HAP) has been formulated as adjuvants in vaccines for human use. However, the optimal properties required for HAP nanoparticles to elicit adjuvanticity and the underlying immunopotentiation mechanisms have not been fully elucidated. Herein, a library of HAP nanorods and nanospheres was synthesized to explore the effect of the particle shape and aspect ratio on the immune responses in vitro and adjuvanticity in vivo. It was demonstrated that long aspect ratio HAP nanorods induced a higher degree of cell membrane depolarization and subsequent uptake, and the internalized particles elicited cathepsin B release and mitochondrial reactive oxygen species generation, which further led to pro-inflammatory responses. Furthermore, the physicochemical property-dependent immunostimulation capacities were correlated with their humoral responses in a murine hepatitis B surface antigen immunization model, with long aspect ratio HAP nanorods inducing higher antigen-specific antibody productions. Importantly, HAP nanorods significantly up-regulated the IFN-γ secretion and CD107α expression on CD8⁺ T cells in immunized mice. Further mechanistic studies demonstrated that HAP nanorods with defined properties exerted immunomodulatory effects by enhanced antigen persistence and immune cell recruitments. Our study provides a rational design strategy for engineered nanomaterial-based vaccine adjuvants.

A proposed insight into the anti-viral potential of metallic nanoparticles against novel coronavirus disease-19 (COVID-19)

BACKGROUND

Over the last ten months since December 2019, the world has faced infectious emerging novel coronavirus disease-2019 (COVID-19) outbreaks that had a massive global impact affecting over 185 countries.

MAIN BODY

Emerging novel COVID-19 is a global health emergency on a pandemic scale that represents a terror to human health through its ability to escape anti-viral measures. Such viral infections impose a great socioeconomic burden, besides global health challenges. This imposes a pressing need for the development of anti-viral therapeutic agents and diagnostic tools that demonstrate multifunctional, target-specific, and non-toxic properties. Nanotheranostics is regarded as a promising approach for the management of different viral infections. Nanotheranostics facilitates targeted drug-delivery of anti-viral therapeutics as well as contributing to the development of diagnostic systems. Multifunctional metallic nanoparticles (NPs) have emerged as innovative theranostic agents that enable sustainable treatment and effective diagnosis. Here we have reviewed current advances in the use of theranostic metallic NPs to fight against COVID-19, and discussed the application as well as limitations associated with nanotechnology-based theranostic approaches.

CONCLUSION

This review verified the potential use of some metal-based NPs as anti-viral nanotheranostic agents. Metal-based NPs could act as carriers that enable the sustainable and targeted delivery of active anti-viral molecules, or as diagnostic agents that allow rapid and sensitive diagnosis of viral infections.

Engineered Nanoparticle Applications for Recombinant Influenza Vaccines

Influenza viruses cause seasonal epidemics and represent a pandemic risk. With current vaccine methods struggling to protect populations against emerging strains, there is a demand for a next-generation flu vaccine capable of providing broad protection. Recombinant biotechnology, combined with nanomedicine techniques, could address this demand by increasing immunogenicity and directing immune responses toward conserved antigenic targets on the virus. Various nanoparticle candidates have been tested for use in vaccines, including virus-like particles, protein and carbohydrate nanoconstructs, antigen-carrying lipid particles, and synthetic and inorganic particles modified for antigen presentation. These methods have yielded some promising results, including protection in animal models against antigenically distinct influenza strains, production of antibodies with broad reactivity, and activation of potent T cell responses. Based on the evidence of current research, it is feasible that the next generation of influenza vaccines will combine recombinant antigens with nanoparticle carriers.

Chimeric Virus-Like Particles and Capsomeres Induce Similar CD8+ T Cell Responses but Differ in Capacity to Induce CD4+ T Cell Responses and Antibody Responses

Despite extensive research, the development of an effective malaria vaccine remains elusive. The induction of robust and sustained T cell and antibody response by vaccination is an urgent unmet need. Chimeric virus-like particles (VLPs) are a promising vaccine platform. VLPs are composed of multiple subunit capsomeres which can be rapidly produced in a cost-effective manner, but the ability of capsomeres to induce antigen-specific cellular immune responses has not been thoroughly investigated. Accordingly, we have compared chimeric VLPs and their sub-unit capsomeres for capacity to induce CD8⁺ and CD4⁺ T cell and antibody responses. We produced chimeric murine polyomavirus VLPs and capsomeres each incorporating defined CD8⁺ T cell, CD4⁺ T cell or B cell repeat epitopes derived from Plasmodium yoelii CSP. VLPs and capsomeres were evaluated using both homologous or heterologous DNA prime/boost immunization regimens for T cell and antibody immunogenicity. Chimeric VLP and capsomere vaccine platforms induced robust CD8⁺ T cell responses at similar levels which was enhanced by a heterologous DNA prime. The capsomere platform was, however, more efficient at inducing CD4⁺ T cell responses and less efficient at inducing antigen-specific antibody responses. Our data suggest that capsomeres, which have significant manufacturing advantages over VLPs, should be considered for diseases where a T cell response is the desired outcome.

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.

Applications and perspectives of nanomaterials in novel vaccine development

Vaccines show great potential for both prophylactic and therapeutic use in infections, cancer, and other diseases. With the rapid development of bio-technologies and materials sciences, nanomaterials are playing essential roles in novel vaccine formulations and can boost antigen effectiveness by operating as delivery systems to enhance antigen processing and/or as immune-potentiating adjuvants to induce or potentiate immune responses. The effect of nanoparticles in vaccinology showed enhanced antigen stability and immunogenicity as well as targeted delivery and slow release. However, obstacles remain due to the lack of fundamental knowledge on the detailed molecular working mechanism and in vivo bio-effects of nanoparticles. This review provides a broad overview of the current improvements in nanoparticles in vaccinology. Modern nanoparticle vaccines are classified by the nanoparticles' action based on either delivery system or immune potentiator approaches. The mechanisms of interaction of nanoparticles with the antigens and the immune system are discussed. Nanoparticle vaccines approved for use are also listed. A fundamental understanding of the in vivo bio-distribution and the fate of nanoparticles will accelerate the rational design of new nanoparticles comprising vaccines in the future.

Polymer-Protein Core-Shell Nanoparticles for Enhanced Antigen Immunogenicity

Nanoengineered vaccine platforms can be modeled after viruses and other pathogens with highly organized and repetitive structures that trigger the host immune system. Here we demonstrated a pyridine-grafted poly(ε-caprolactone)-based polymer-protein core-shell nanoparticles (PPCS-NPs) platform can effectively trigger the host immune system and lead to significantly higher antibody titers.

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

INTRODUCTION

Allergen-specific immunotherapy is the only curative approach for the treatment of allergies. There is an urgent need for improved therapies, which increase both, efficacy and patient compliance. Novel routes of immunization and the use of more advanced vaccine platforms have gained heightened interest in this field. Areas covered: The current status of allergen-specific immunotherapy is summarized and novel routes of immunization and their challenges in the clinics are critically discussed. The use of nanoparticles as novel delivery system for allergy vaccines is comprehensively reviewed. Specifically, the advantages of silica nanoparticles as vaccine carriers and adjuvants are summarized. Expert opinion: Future allergen-specific immunotherapy will combine engineered hypoallergenic vaccines with novel routes of administration, such as the skin. Due to their biodegradability, and the easiness to introduce surface modifications, silica nanoparticles are promising candidates for tailor-made vaccines. By covalently linking allergens and polysaccharides to silica nanoparticles, a versatile vaccination platform can be designed to specifically target antigen-presenting cells, render the formulation hypoallergenic, and introduce immunomodulatory functions. Combining potent skin vaccination methods, such as fractional laser ablation, with nanoparticle-based vaccines addresses all the requirements for safe and efficient therapy of allergic diseases.

Cerium dioxide nanoparticles increase immunogenicity of the influenza vaccine

We have demonstrated the influence of cerium dioxide nanoparticles on the immunogenicity of the influenza vaccine on an example of liquid split inactivated Vaxigrip vaccine. Antibody titers were analyzed using the hemagglutination inhibition (HI) assay. Seroprotection, seroconversion, the geometric mean titers (GMTs) and the factor increase (FI) in the GMTs were calculated. The effect of nano-ceria surface stabilizer on the enhancement of immunogenicity was shown. The vaccine modified by citrate-stabilized nano-ceria, in contrast to a non-modified Vaxigrip vaccine, did not provide an adequate level of seroprotection, and seroconversion after vaccination was 66.7% on days 49-63 for virus strain А(H1N1) and 100% on day 49 for virus strain B/Yamagata. For the low immunogenic influenza B virus, the rise in antibody titers (GMT/IF) was 24.38/3.28 after the first injection and 50.40/6.79 on day 49. For the vaccine modified by non-stabilized nano-ceria, for all virus strains under study, on day 63, upon immunization notable levels of seroprotection, seroconversion and GMT/IF were registered (higher than for the non-modified Vaxigrip vaccine). The successful attempt to modify the influenza vaccine demonstrates the possible ways of increasing the specific activity of vaccines using nano-ceria.

A novel lipid nanoparticle adjuvant significantly enhances B cell and T cell responses to sub-unit vaccine antigens

Sub-unit vaccines are primarily designed to include antigens required to elicit protective immune responses and to be safer than whole-inactivated or live-attenuated vaccines. But their purity and inability to self-adjuvant often result in weaker immunogenicity. Emerging evidence suggests that bio-engineered nanoparticles can be used as immunomodulatory adjuvants. Therefore, in this study we explored the potential of novel Merck-proprietary lipid nanoparticle (LNP) formulations to enhance immune responses to sub-unit viral antigens. Immunization of BALB/c and C57BL/6 mice revealed that LNPs alone or in combination with a synthetic TLR9 agonist, immune-modulatory oligonucleotides, IMO-2125 (IMO), significantly enhanced immune responses to hepatitis B virus surface antigen (HBsAg) and ovalbumin (OVA). LNPs enhanced total B-cell responses to both antigens tested, to levels comparable to known vaccine adjuvants including aluminum based adjuvant, IMO alone and a TLR4 agonist, 3-O-deactytaled monophosphoryl lipid A (MPL). Investigation of the quality of B-cell responses demonstrated that the combination of LNP with IMO agonist elicited a stronger Th1-type response (based on the IgG2a:IgG1 ratio) than levels achieved with IMO alone. Furthermore, the LNP adjuvant significantly enhanced antigen specific cell-mediated immune responses. In ELISPOT assays, depletion of specific subsets of T cells revealed that the LNPs elicited potent antigen-specific CD4(+) and CD8(+)T cell responses. Intracellular FACS analyses revealed that LNP and LNP+IMO formulated antigens led to higher frequency of antigen-specific IFNγ(+)TNFα(+)IL-2(+), multi-functional CD8(+)T cell responses, than unadjuvanted vaccine or vaccine with IMO only. Overall, our results demonstrate that lipid nanoparticles can serve as future sub-unit vaccine adjuvants to boost both B-cell and T-cell responses in vivo, and that addition of IMO can be used to manipulate the quality of immune responses.

Nanovaccines for malaria using Plasmodium falciparum antigen Pfs25 attached gold nanoparticles

Malaria transmission-blocking vaccines (TBV) targeting sexual stages of the parasite represent an ideal intervention to reduce the burden of the disease and eventual elimination at the population level in endemic regions. Immune responses against sexual stage antigens impair the development of parasite inside the mosquitoes. Target antigens identified in Plasmodium falciparum include surface proteins Pfs230 and Pfs48/45 in male and female gametocytes and Pfs25 expressed in zygotes and ookinetes. The latter has undergone extensive evaluation in pre-clinical and phase I clinical trials and remains one of the leading target antigens for the development of TBV. Pfs25 has a complex tertiary structure characterized by four EGF-like repeat motifs formed by 11 disulfide bonds, and it has been rather difficult to obtain Pfs25 as a homogenous product in native conformation in any heterologous expression system. Recently, we have reported expression of codon-harmonized recombinant Pfs25 in Escherichia coli (CHrPfs25) and which elicited highly potent malaria transmission-blocking antibodies in mice. In the current study, we investigated CHrPfs25 along with gold nanoparticles of different shapes, size and physicochemical properties as adjuvants for induction of transmission blocking immunity. The results revealed that CHrPfs25 delivered with various gold nanoparticles elicited strong transmission blocking antibodies and suggested that gold nanoparticles based formulations can be developed as nanovaccines to enhance the immunogenicity of vaccine antigens.

M2e-immobilized gold nanoparticles as influenza A vaccine: Role of soluble M2e and longevity of protection

Influenza virus causes seasonal epidemics and also poses a high risk for pandemics. To develop a broadly cross-protective influenza vaccine we have previously shown that a formulation consisting of the extracellular domain of M2 membrane protein (M2e) immobilized on gold nanoparticles (AuNPs) and soluble CpG as an adjuvant can elicit protective immunity against different influenza A subtypes. The vaccine formulation contains M2e that is immobilized on AuNPs, and an excess amount that is freely dissolved in solution, whose role in inducing protective immunity against virus infection is unclear. Using a mouse model, the current study shows that inclusion of excess soluble M2e antigen along with M2e immobilized on AuNPs is vital for inducing high levels of antibody response, and in providing complete protection against lethal influenza virus challenge. We also show that the vaccine induces long-lasting protection against mortality and morbidity upon lethal challenge with influenza A virus.

Non-carrier nanoparticles adjuvant modular protein vaccine in a particle-dependent manner

Nanoparticles are increasingly used to adjuvant vaccine formulations due to their biocompatibility, ease of manufacture and the opportunity to tailor their size, shape, and physicochemical properties. The efficacy of similarly-sized silica (Si-OH), poly (D,L-lactic-co-glycolic acid) (PLGA) and poly caprolactone (PCL) nanoparticles (nps) to adjuvant recombinant capsomere presenting antigenic M2e modular peptide from Influenza A virus (CapM2e) was investigated in vivo. Formulation of CapM2e with Si-OH or PLGA nps significantly boosted the immunogenicity of modular capsomeres, even though CapM2e was not actively attached to the nanoparticles prior to injection (i.e., formulation was by simple mixing). In contrast, PCL nps showed no significant adjuvant effect using this simple-mixing approach. The immune response induced by CapM2e alone or formulated with nps was antibody-biased with very high antigen-specific antibody titer and less than 20 cells per million splenocytes secreting interferon gamma. Modification of silica nanoparticle surface properties through amine functionalization and pegylation did not lead to significant changes in immune response. This study confirms that simple mixing-based formulation can lead to effective adjuvanting of antigenic protein, though with antibody titer dependent on nanoparticle physicochemical properties.

Silica nanoparticles as the adjuvant for the immunisation of mice using hepatitis B core virus-like particles

Advances in nanotechnology and nanomaterials have facilitated the development of silicon dioxide, or Silica, particles as a promising immunological adjuvant for the generation of novel prophylactic and therapeutic vaccines. In the present study, we have compared the adjuvanting potential of commercially available Silica nanoparticles (initial particles size of 10–20 nm) with that of aluminium hydroxide, or Alum, as well as that of complete and incomplete Freund's adjuvants for the immunisation of BALB/c mice with virus-like particles (VLPs) formed by recombinant full-length Hepatitis B virus core (HBc) protein. The induction of B-cell and T-cell responses was studied after immunisation. Silica nanoparticles were able to adsorb maximally 40% of the added HBc, whereas the adsorption capacity of Alum exceeded 90% at the same VLPs/adjuvant ratio. Both Silica and Alum formed large complexes with HBc VLPs that sedimented rapidly after formulation, as detected by dynamic light scattering, spectrophotometry, and electron microscopy. Both Silica and Alum augmented the humoral response against HBc VLPs to the high anti-HBc level in the case of intraperitoneal immunisation, whereas in subcutaneous immunisation, the Silica-adjuvanted anti-HBc level even exceeded the level adjuvanted by Alum. The adjuvanting of HBc VLPs by Silica resulted in the same typical IgG2a/IgG1 ratios as in the case of the adjuvanting by Alum. The combination of Silica with monophosphoryl lipid A (MPL) led to the same enhancement of the HBc-specific T-cell induction as in the case of the Alum and MPL combination. These findings demonstrate that Silica is not a weaker putative adjuvant than Alum for induction of B-cell and T-cell responses against recombinant HBc VLPs. This finding may have an essential impact on the development of the set of Silica-adjuvanted vaccines based on a long list of HBc-derived virus-like particles as the biological component.