Optimization of stability, encapsulation, release, and cross-priming of tumor antigen-containing PLGA nanoparticles

Advanced Nanomedicine for High-Risk HPV-Driven Head and Neck Cancer

The incidence of high-risk Human Papillomavirus (HR-HPV)-driven head and neck squamous cell carcinoma (HNSCC) is on the rise globally. HR-HPV-driven HNSCC displays molecular and clinical characteristics distinct from HPV-uninvolved cases. Therapeutic strategies for HR-HPV-driven HNSCC are under investigation. HR-HPVs encode the oncogenes E6 and E7, which are essential in tumorigenesis. Meanwhile, involvement of E6 and E7 provides attractive targets for developing new therapeutic regimen. Here we will review some of the recent advancements observed in preclinical studies and clinical trials on HR-HPV-driven HNSCC, focusing on nanotechnology related methods. Materials science innovation leads to great improvement for cancer therapeutics including HNSCC. This article discusses HPV-E6 or -E7- based vaccines, based on plasmid, messenger RNA or peptide, at their current stage of development and testing as well as how nanoparticles can be designed to target and access cancer cells and activate certain immunology pathways besides serving as a delivery vehicle. Nanotechnology was also used for chemotherapy and photothermal treatment. Short interference RNA targeting E6/E7 showed some potential in animal models. Gene editing by CRISPR-CAS9 combined with other treatments has also been assessed. These advancements have the potential to improve the outcome in HR-HPV-driven HNSCC, however breakthroughs are still to be awaited with nanomedicine playing an important role.

The role of T-cells in head and neck squamous cell carcinoma: From immunity to immunotherapy

Head and neck squamous cell carcinoma (HNSCC) encompass a group of complex entities of tumours affecting the aerodigestive upper tract. The main risk factors are strongly related to tobacco and alcohol consumption, but also HPV infection is often associated. Surgery, radiotherapy and/or chemotherapy are the standard treatments, though the 5-year overall survival is less than 50%. The advances in genomics, molecular medicine, immunology, and nanotechnology have shed a light on tumour biology which helps clinical researchers to obtain more efficacious and less toxic therapies. Head and neck tumours possess different immune escape mechanisms including diminishing the immune response through modulating immune checkpoints, in addition to the recruitment and differentiation of suppressive immune cells. The insights into the HNSCC biology and its strong interaction with the tumour microenvironment highlights the role of immunomodulating agents. Recently, the knowledge of the immunological features of these tumours has paved the way for the discovery of effective biomarkers that allow a better selection of patients with odds of improving overall survival through immunotherapy. Specially biomarkers regarding immune checkpoint inhibitors antibodies, such as anti-PD-1/PD-L1 and anti-CTLA-4 in combination with standard therapy or as monotherapy. New immunotherapies to treat head and neck cancer carcinomas, such as CAR T cells and nanoparticles have been the center of attention and in this review, we discuss the necessity of finding targets for the T cell in the cancer cells to generate CAR T cells, but also the relevance of evaluating specificity and safety of those therapies.

Polymer Nanoparticle-Mediated Delivery of Oxidized Tumor Lysate-Based Cancer Vaccines

Cancer vaccination is a powerful strategy to combat cancer. A very attractive approach to prime the immune system against cancer cells involves the use of tumor lysate as antigen source. The immunogenicity of tumor lysate can be further enhanced by treatment with hypochlorous acid. This study explores poly(lactic-co-glycolic acid) (PLGA) nanoparticles to enhance the delivery of oxidized tumor lysate to dendritic cells. Using human donor-derived dendritic cells, it is found that the use of PLGA nanoparticles enhances antigen uptake and dendritic cell maturation, as compared to the use of the free tumor lysate. The ability of the activated dendritic cells to stimulate autologous peripheral blood mononuclear cells (PBMCs) is assessed in vitro by coculturing PBMCs with A375 melanoma cells. Live cell imaging analysis of this experiment highlights the potential of nanoparticle-mediated dendritic-cell-based vaccination approaches. Finally, the efficacy of the PLGA nanoparticle formulation is evaluated in vivo in a therapeutic vaccination study using B16F10 tumor-bearing C57BL/6J mice. Animals that are challenged with the polymer nanoparticle-based oxidized tumor lysate formulation survive for up to 50 days, in contrast to a maximum of 41 days for the group that receives the corresponding free oxidized tumor lysate-based vaccine.

Mannosylated polylactic-co-glycolic acid (MN-PLGA) nanoparticles induce potent anti-tumor immunity in murine model of breast cancer

Nanoparticle-based cancer immunotherapy is considered a novel and promising therapeutic strategy aimed at stimulating host immune responses against tumors. To this end, in the present study, mannan-decorated polylactic-co-glycolic acid (PLGA) nanoparticles containing tumor cell lysate (TCL) and poly riboinosinic polycytidylic acid (poly I:C) were used as antigen delivery systems to immunize breast tumor-bearing Balb/c mice. PLGA nanoparticles were fabricated employing a double emulsion solvent evaporation method. The formation of spherical and uniform nanoparticles (NPs) ranging 150-250 nm was detected by field emission scanning electron microscopy (FESEM) and dynamic light scattering (DLS). Four nanoformulation were used to treat mice and vaccination-induced immunological responses. Tumor regression and overall survival rate were evaluated in four experimental groups. Tumor cell lysate and poly I:C loaded mannan-decorated nanoparticles (TCL-Poly I:C) NP-MN caused a significant decrease in tumor growth and 2- to 3-fold improvement in survival times of the treated mice. The NPs with or without mannan decoration elicited stronger responses in terms of lymphocyte proliferation, delayed-type hypersensitivity and CD107a expression. Moreover, our data indicated that the production of IFN-γ and IL-2 increased while the production of IL-4 and IL-10 decreased in splenocytes culture supernatants. In the pathological evaluations, we found that necrosis and immune cells infiltration rate in the tumor tissue of the treated mice was elevated, while tumor cellularity and lung metastases significantly decreased in particular in the group that received (TCL-Poly I:C) NP-MN. Altogether, our findings suggested that the mannan-decorated PLGA NPs antigen delivery system had significant anti-tumor effects against the murine model of breast cancer and it could be considered as a step forward to human breast cancer immunotherapy.

Insights into Nanomedicine for Immunotherapeutics in Squamous Cell Carcinoma of the head and neck

Immunotherapies such as immune checkpoint blockade benefit only a portion of patients with head and neck squamous cell carcinoma. The multidisciplinary field of nanomedicine is emerging as a promising strategy to achieve maximal anti-tumor effect in cancer immunotherapy and to turn non-responders into responders. Various methods have been developed to deliver therapeutic agents that can overcome bio-barriers, improve therapeutic delivery into the tumor and lymphoid tissues and reduce adverse effects in normal tissues. Additional modification strategies also have been employed to improve targeting and boost cytotoxic T cell-based immune responses. Here, we review the state-of-the-art use of nanotechnologies in the laboratory, in advanced preclinical phases as well as those running through clinical trials assessing their advantages and challenges.

Cationic polymer modified PLGA nanoparticles encapsulating Alhagi honey polysaccharides as a vaccine delivery system for ovalbumin to improve immune responses

Background: Poly (lactic-co-glycolic acid) (PLGA) nanoparticles and surface modified PLGA nanoparticles have been widely studied as antigens or drugs carriers due to their controlled release characteristics and biocompatibility. However, most PLGA nanoparticles have lower antigens loading efficiency and adjuvanticity.

Purpose: The aim of this study was to improve the antigen loading efficiency and adjuvant activity of PLGA nanoparticles.

Materials and methods: Surface cationic polymer modification can improve the antigens loading efficiency of PLGA nanoparticles by surface adsorption. Therefore, in this study, chitosan modified PLGA nanoparticles (CS-AHPP/OVA), polyethyleneimine modified PLGA nanoparticles (PEI-AHPP/OVA), and ε-Poly-L-lysine modified PLGA nanoparticles (εPL-AHPP/OVA) were prepared as antigen delivery carriers to investigate the characterization and stability of these nanoparticles. These nanoparticles were evaluated for their efficacies as adjuvants pre- and post-modification.

Results: The AHP and OVA-loaded PLGA nanoparticles (AHPP/OVA) were positively charged after surface cationic polymers modification, and their structural integrity was maintained. Their antigen loading capacity and stability of nanoparticles were improved by the surface cationic polymers modification. Increased positive surface charge resulted in greater OVA adsorption capacity. Among AHPP/OVA and the three surface cationic polymers synthesized from modified PLGA nanoparticles, PEI-AHPP/OVA showed the highest antigen loading efficiency and good stability. AHPP/OVA, CS-AHPP/OVA PEI-AHPP/OVA, and εPL-AHPP/OVA formulations significantly enhanced lymphocyte proliferation and improved the ratio of CD4+/CD8+ T cells. In addition, AHPP/OVA, PEI-AHPP/OVA and εPL-AHPP/OVA formulations induced secretion of cytokines (TNF-α, IFN-γ, IL-4, and IL-6), antibodies (IgG) and antibody subtypes (IgG1 and IgG2a) in immunized mice. These results demonstrate that these formulations generated a strong Th1-biased immune response. Among them, PEI-AHPP/OVA induced the strongest Th1-biased immune response.

Conclusion: In conclusion, PEI-AHPP/OVA nanoparticles may be a potential antigen delivery system for the induction of strong immune responses.

The era of bioengineering: how will this affect the next generation of cancer immunotherapy?

Background

Immunotherapy consists of activating the patient’s immune system to fight cancer and has the great potential of preventing future relapses thanks to immunological memory. A great variety of strategies have emerged to harness the immune system against tumors, from the administration of immunomodulatory agents that activate immune cells, to therapeutic vaccines or infusion of previously activated cancer-specific T cells. However, despite great recent progress many difficulties still remain, which prevent the widespread use of immunotherapy. Some of these limitations include: systemic toxicity, weak immune cellular responses or persistence over time and most ultimately costly and time-consuming procedures.

Main body

Synthetic and natural biomaterials hold great potential to address these hurdles providing biocompatible systems capable of targeted local delivery, co-delivery, and controlled and/or sustained release. In this review we discuss some of the bioengineered solutions and approaches developed so far and how biomaterials can be further implemented to help and shape the future of cancer immunotherapy.

Conclusion

The bioengineering strategies here presented constitute a powerful toolkit to develop safe and successful novel cancer immunotherapies.

Recruitment of bone marrow CD11b+Gr-1+ cells by polymeric nanoparticles for antigen cross-presentation

The objective of this study was to investigate the function of poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) on the activation of antigen-specific CD8⁺ T cell responses via the CD11b⁺Gr^-1⁺ myeloid subpopulations in murine bone marrow (BM). PLGA NPs containing ovalbumin (OVA) were fabricated by the double-emulsion method. The CD11b⁺Gr-1^lowLy-6C^high and CD11b⁺Gr-1^highLy-6C^low subsets from mice bone marrow were sorted and treated with the PLGA/OVA NPs, followed by co-culture with the carboxyfluorescein succinimidyl ester (CFSE)-labelled OT-I CD8⁺ cells. Co-culture of OT-I CD8⁺ T cells with PLGA/OVA NPs-primed CD11b⁺Gr-1⁺ subsets upregulated the expression of IL-2, TNF-α, INF-γ, granzyme B, and perforin, resulting in proliferation of CD8⁺ T cells and differentiation into effector cytotoxic T lymphocytes (CTLs). In vivo proliferation of CFSE-labelled OT-I CD8⁺ cells in response to OVA was also obtained in the animals immunized with PLGA/OVA NPs. The results presented in this study demonstrate the ability of polymeric NPs to recruit two CD11b⁺Gr^-1⁺ myeloid subsets for effective presentation of exogenous antigen to OT-I CD8⁺ T cells in the context of major histocompatibility complex (MHC) class I, leading to an induction of antigen-specific cell proliferation and differentiation into effector cells.

Controlled release of antigen and Toll-like receptor ligands from PLGA nanoparticles enhances immunogenicity

AIM

Dendritic cells rapidly capture nanoparticles and induce a potent cellular immune response. It is yet unknown whether the immunological response induced by slow release of encapsulated versus soluble antigen and adjuvant is superior.

MATERIALS & METHODS

The kinetics of poly(lactic-co-glycolic acid) PLGA nanoparticles antigen release was studied by the DQ-bovine serum albumin (BSA) self-quenching antigen model. The immunological response induced was evaluated by means of dendritic cell activation/maturation markers, cytokine production and their ability to drive antigen-specific T-cell proliferation.

RESULTS & CONCLUSION

PLGA-encapsulated antigen and adjuvant showed an enhanced T-cell response when compared with soluble vaccine components by increasing antigenicity and adjuvanticity. Although the kinetic profile followed the same pattern, encapsulation increased strength and duration of the response.

Non-invasive administration of biodegradable nano-carrier vaccines

Polymeric nanoparticulate carriers play an important role and holding a significant potential for the development of novel immunomodulatory agents as easily they are taken up by antigen presenting cells. They allow an enhanced antigen stability, better immunogenicity and immunostimulatory effect with sustained and controlled release of the antigen to the target sites. Better information and vital understanding of mechanism of action, interaction of such vectors with the APCs and dendritic cells and antigen release kinetics in immunomodulatory effects, and improved knowledge of their in vivo fate and distribution are now needed, those collectively would speed up the rational strategies of nanoparticles as carriers for vaccines and other protein antigens. The evolution of such innovative adjuvants for protein and DNA immunizations are an exciting and growing zone in immunology, which may enhance the clinical outcomes in many infectious and non-infectious diseases. This review summarizes the recent advances in nano-vaccinology with polymeric (especially biodegradable) carriers, their methods of preparation, surface modification, their interaction with antigen presenting cells, release of antigens, its kinetics and mechanism in the delivery of vaccines via non-invasive routes.

Nanomedicine in the development of anti-HIV microbicides

Prevention plays an invaluable role in the fight against HIV/AIDS. The use of microbicides is considered an interesting potential approach for topical pre-exposure prophylaxis of HIV sexual transmission. The prospects of having an effective product available are expected to be fulfilled in the near future as driven by recent and forthcoming results of clinical trials. Different dosage forms and delivery strategies have been proposed and tested for multiple microbicide drug candidates presently at different stages of the development pipeline. One particularly interesting approach comprises the application of nanomedicine principles to the development of novel anti-HIV microbicides, but its implications to efficacy and safety are not yet fully understood. Nanotechnology-based systems, either presenting inherent anti-HIV activity or acting as drug nanocarriers, may significantly influence features such as drug solubility, stability of active payloads, drug release, interactions between active moieties and virus/cells, intracellular drug delivery, drug targeting, safety, antiviral activity, mucoadhesive behavior, drug distribution and tissue penetration, and pharmacokinetics. The present manuscript provides a comprehensive and holistic overview of these topics as relevant to the development of vaginal and rectal microbicides. In particular, recent advances pertaining inherently active microbicide nanosystems and microbicide drug nanocarriers are discussed.

In vitro controlled release of antigen in dendritic cells using pH-sensitive liposome-polymeric hybrid nanoparticles

A hybrid nanoparticle (NP) consisting of a pH sensitive lipid shell and a poly(lactic-co-glycolic) acid (PLGA) core was constructed. This hybrid NP has a mean size of 120.1 ± 8.8 nm and positively charged surface (zeta potential of 14.2 ± 1.4 mV). The lipid shell of the hybrid NP was quickly disintegrated in buffer with a pH of 5.5, which resembles the acidic environment of endosomes in dendritic cell (DC). Less than 20% of the antigen enclosed in pH-sensitive hybrid NP was released into human serum at physiological pH within 24 h, but more than 40% of the enclosed antigen was released within 8 h after pH was adjusted to 5.5. Fast uptake of the pH sensitive hybrid NP by DC was also observed. It was found that pH sensitive hybrid NP displayed faster degradation and antigen release compared to regular hybrid NPs after uptake by DC.

Nucleic acid vaccination strategies against infectious diseases

INTRODUCTION

Gene vaccines are an interesting and emerging alternative for the prevention of infectious diseases, as well as in the treatment of other pathologies including cancer, allergies, autoimmune diseases, or even drug dependencies. When applied to the target organism, these vaccines induce the expression of encoded antigens and elicit the corresponding immune response, with the potential ability of being able to induce antibody-, helper T cell-, and cytotoxic T cell-mediated immune responses.

AREAS COVERED

Special attention is paid to the variety of adjuvants that may be co-administered to enhance and/or to modulate immune responses, and to the methods of delivery. Finally, this article reviews the efficacy data of gene vaccines against infectious diseases released from current clinical trials.

EXPERT OPINION

Taken together, this approach will have a major impact on future strategies for the prevention of infectious diseases. Better-designed nucleic acid constructs, novel delivery technologies, as well as the clarification of the mechanisms for antigen presentation will improve the potential applications of this vaccination strategy against microbial pathogens.

Enhancement of anti-tumor effect of particulate vaccine delivery system by 'bacteriomimetic' CpG functionalization of poly-lactic-co-glycolic acid nanoparticles

AIM

Low immunogenicity remains a major obstacle in realizing the full potential of cancer vaccines. In this study, we evaluated CpG-coated tumor antigen (Tag)-encapsulating 'bacteriomimetic' nanoparticles (CpG-nanoparticle [NP]-Tag NPs) as an approach to enhance anti-tumor immunity.

MATERIALS & METHODS

CpG-NP-Tag NPs were synthesized, characterized for their physicochemical properties and tested in vivo.

RESULTS

We found CpG predosing followed by intraperitoneal (IP) immunization with CpG-NP-Tag NPs significantly attenuated tumor growth in female BALB/c mice compared with respective controls. Histopathological and Immunofluorescence data revealed CpG-NP-Tag tumors had lower proliferation, higher apoptotic activity, greater CD4(+) and CD8(+) T cell infiltration as well as higher IFN-γ levels as compared with control groups.

CONCLUSION

Our findings suggest CpG-NP-Tag NPs can enhance anti-tumor effect of nanoparticulate tumor vaccination system.

A gold nanoparticle-linked glycoconjugate vaccine against Burkholderia mallei

Burkholderia mallei are Gram-negative bacteria, responsible for the disease glanders. B. mallei has recently been classified as a Tier 1 agent owing to the fact that this bacterial species can be weaponised for aerosol release, has a high mortality rate and demonstrates multi-drug resistance. Furthermore, there is no licensed vaccine available against this pathogen. Lipopolysaccharide (LPS) has previously been identified as playing an important role in generating host protection against Burkholderia infection. In this study, we present gold nanoparticles (AuNPs) functionalised with a glycoconjugate vaccine against glanders. AuNPs were covalently coupled with one of three different protein carriers (TetHc, Hcp1 and FliC) followed by conjugation to LPS purified from a non-virulent clonal relative, B. thailandensis. Glycoconjugated LPS generated significantly higher antibody titres compared with LPS alone. Further, they improved protection against a lethal inhalation challenge of B. mallei in the murine model of infection.

FROM THE CLINICAL EDITOR

Burkholderia mallei is associated with multi-drug resistance, high mortality and potentials for weaponization through aerosol inhalation. The authors of this study present gold nanoparticles (AuNPs) functionalized with a glycoconjugate vaccine against this Gram negative bacterium demonstrating promising results in a murine model even with the aerosolized form of B. Mallei.

Recent progress towards development of a Shigella vaccine

The burden of dysentery due to shigellosis among children in the developing world is still a major concern. A safe and efficacious vaccine against this disease is a priority, since no licensed vaccine is available. This review provides an update of vaccine achievements focusing on subunit vaccine strategies and the forthcoming strategies surrounding this approach. In particular, this review explores several aspects of the pathogenesis of shigellosis and the elicited immune response as being the basis of vaccine requirements. The use of appropriate Shigella antigens, together with the right adjuvants, may offer safety, efficacy and more convenient delivery methods for massive worldwide vaccination campaigns.