Intranasal Immunization With Nanoparticles Containing an Orientia tsutsugamushi Protein Vaccine Candidate and a Polysorbitol Transporter Adjuvant Enhances Both Humoral and Cellular Immune Responses

Scrub typhus, a mite-borne infectious disease, is caused by Orientia tsutsugamushi. Despite many attempts to develop a protective strategy, an effective preventive vaccine has not been developed. The identification of appropriate Ags that cover diverse antigenic strains and provide long-lasting immunity is a fundamental challenge in the development of a scrub typhus vaccine. We investigated whether this limitation could be overcome by harnessing the nanoparticle-forming polysorbitol transporter (PST) for an O. tsutsugamushi vaccine strategy. Two target proteins, 56-kDa type-specific Ag (TSA56) and surface cell Ag A (ScaA) were used as vaccine candidates. PST formed stable nano-size complexes with TSA56 (TSA56-PST) and ScaA (ScaA-PST); neither exhibited cytotoxicity. The formation of Ag-specific IgG2a, IgG2b, and IgA in mice was enhanced by intranasal vaccination with TSA56-PST or ScaA-PST. The vaccines containing PST induced Ag-specific proliferation of CD8+ and CD4+ T cells. Furthermore, the vaccines containing PST improved the mouse survival against O. tsutsugamushi infection. Collectively, the present study indicated that PST could enhance both Ag-specific humoral immunity and T cell response, which are essential to effectively confer protective immunity against O. tsutsugamushi infection. These findings suggest that PST has potential for use in an intranasal vaccination strategy.

RNA nanotechnology: A new chapter in targeted therapy

Nanoparticles have been widely studied in the fields of biotechnology, pharmacy, optics and medicine and have broad application prospects. Numerous studies have shown significant interest in utilizing nanoparticles for chemically coating or coupling drugs, aiming to address the challenges of drug delivery, including degradability and uncertainty. Furthermore, the utilization of lipid nanoparticles loaded with novel coronavirus antigen mRNA to control the COVID-19 pandemic has led to a notable surge in research on nanoparticle vaccines. Hence, nanoparticles have emerged as a crucial delivery system for disease prevention and treatment, bearing immense significance. Current research highlights that nanoparticles offer superior efficacy and potential compared to conventional drug treatment and prevention methods. Notably, for drug delivery applications, it is imperative to utilize biodegradable nanoparticles. This paper reviews the structures and characteristics of various biodegradable nanoparticles and their applications in biomedicine in order to inspire more researchers to further explore the functions of nanoparticles. RNA plays a pivotal role in regulating the occurrence and progression of diseases, but its inherent susceptibility to degradation poses a challenge. In light of this, we conducted a comprehensive review of the research advancements concerning RNA-containing biodegradable nanoparticles in the realm of disease prevention and treatment, focusing on cancer, inflammatory diseases, and viral infections.

Nano-vaccines for gene delivery against HIV-1 infection

INTRODUCTION

Over the last four decades, human immunodeficiency virus type 1 (HIV-1) infection has been a major public health concern. It is acknowledged that an effective vaccine remains the best hope for eliminating the HIV-1 pandemic. The prophylaxis of HIV-1 infection remains a central theme because of the absence of an available HIV-1 vaccine. The incapability of conventional delivery strategies to induce potent immunity is a crucial task to overcome and ultimately lead to a major obstacle in HIV-1 vaccine research.

AREAS COVERED

The literature search was conducted in the following databases: PubMed, Web of Science, and Embase. Nano-platforms based vaccines have proven prophylaxis of various diseases for effectively activating the immune system. Nano-vaccines, including non-viral and viral vectored nano-vaccines, are in a position to improve the effectiveness of HIV-1 antigen delivery and enhance the innate and adaptive immune responses against HIV-1. Compared to traditional vaccination strategies, genetic immunization can elicit a long-term immune response to provide protective immunity for HIV-1 prevention.

EXPERT OPINION

The research progress on nano-vaccines for gene delivery against HIV-1 was discussed. The vaccine strategies based on nano-platforms that are being applied to stimulate effective HIV-1-specific cellular and humoral immune responses were particularly emphasized.

Bioinspired nano-vaccine construction by antigen pre-degradation for boosting cancer personalized immunotherapy

Cancer vaccines-based cancer immunotherapy has drawn widespread concern. However, insufficient cancer antigens and inefficient antigen presentation lead to low immune response rate, which greatly restrict the practical application of cancer vaccines. Here, inspired by intracellular proteasome-mediated protein degradation pathway, we report an antigen presentation simplification strategy by extracellular degradation of antigen proteins into peptides with proteolytic enzyme for improving the utilization of cancer antigens and arousing restricted cancer immunity. The pre-degraded antigen peptides are first validated to exhibit an increased capacity on antigen-presenting cell (APC) stimulation compared with proteins and still reserve antigen specificity and major histocompatibility complex (MHC) affinity. Furthermore, by coordinating the pre-degraded peptides with calcium phosphate nanoparticles (CaP), a CaP-peptide vaccine (CaP-Pep) is constructed, which is verified to induce an efficient personalized immune response in vivo for multi-model anti-cancer therapy. Notably, this bioinspired strategy based on extracellular enzymatic hydrolysis for vaccine construction is not only applicable for multiple types of cancers, but also shows great potential in expanding immunology fields and translational medicine.

Intracellular signaling pathway in dendritic cells and antigen transport pathway in vivo mediated by an OVA@DDAB/PLGA nano-vaccine

Background

Poly(D, L-lactic-co-glycolic acid) (PLGA) nanoparticles have potential applications as a vaccine adjuvant and delivery system due to its unique advantages as biodegradability and biocompatibility.

Experimental

We fabricated cationic solid lipid nanoparticles using PLGA and dimethyl-dioctadecyl-ammonium bromide (DDAB), followed by loading of model antigen OVA (antigen ovalbumin, OVA_257-264) to form an OVA@DDAB/PLGA nano-vaccine. And we investigated the intracellular signaling pathway in dendritic cells in vitro and antigen transport pathway and immune response in vivo mediated by an OVA@DDAB/PLGA nano-vaccine.

Results

In vitro experiments revealed that the antigen uptake of BMDCs after nanovaccine incubation was two times higher than pure OVA or OVA@Al at 12 h. The BMDCs were well activated by p38 MAPK signaling pathway. Furthermore, the nano-vaccine induced antigen escape from lysosome into cytoplasm with 10 times increased cross-presentation activity than those of OVA or OVA@Al. Regarding the transport of antigen into draining lymph nodes (LNs), the nano-vaccine could rapidly transfer antigen to LNs by passive lymphatic drainage and active DC transport. The antigen⁺ cells in inguinal/popliteal LNs for the nano-vaccine were increased over two folds comparing to OVA@Al and OVA at 12 h. Moreover, the antigen of nano-vaccine stayed in LNs for over 7 days, germinal center formation over two folds higher than those of OVA@Al and OVA. After immunization, the nano-vaccine induced a much higher ratio of IgG2c/IgG1 than OVA@Al. It also effectively activated CD4⁺ T, CD8⁺ T and B cells for immune memory with a strong cellular response.

Conclusion

These results indicated that DDAB/PLGA NP was a potent platform to improve vaccine immunogenicity by p38 signaling pathway in BMDCs, enhancing transport of antigens to LNs, and higher immunity response.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01116-8.

Design of a chitosan-based nano vaccine against epsilon toxin of Clostridium perfringens type D and evaluation of its immunogenicity in BALB/c mice

Background and purpose

Clostridium perfringens is an anaerobic, spore-forming, and pathogenic bacterium that causes intestinal diseases in humans and animals. In these cases, therapeutic intervention is challenging; because the disease progresses much rapidly. This bacterium can produce 5 main toxins (alpha, beta, epsilon, iota, and a type of enterotoxin) among which the epsilon toxin (ETX) is used for bioterrorism. This toxin can be prevented by immunization with specific immunogenic vaccines. In the present research, we aimed at developing a recombinant chitosan-based nano-vaccine against ETX of C. perfringens and evaluate its effects on the antibody titration against epsilon toxin in BALB/c mice as the vaccine model.

Experimental approach

The etx gene from C. perfringens type D was cloned and expressed in E. coli. After analysis by SDS-PAGE and western blotting, the expressed products were purified, and the obtained proteins were used for immunization in mice as a chitosan nanoparticle containing recombinant, purified ETX, and protein.

Findings/Results

The results of ELISA showed that IgA antibody serum level increased sufficiently using recombinant protein with nanoparticle as an oral and injectable formulation. IgG antibody titers increased significantly after administrating the recombinant proteins with nanoparticles through both oral delivery and intravenous injection.

Conclusion and implication

In conclusion, the recombinant ETX is suggested as a good candidate for vaccine production against diseases caused by ETX of C. perfringens type D.

Targeted co-delivery of Trp-2 polypeptide and monophosphoryl lipid A by pH-sensitive poly (β-amino ester) nano-vaccines for melanoma

Dendritic cell (DC)-targeted vaccines based on nanotechnology are a promising strategy to efficiently induce potent immune responses. We synthesized and manufactured a mannose-modified poly (β-amino ester) (PBAE) nano-vaccines with easily tuneable and pH-sensitive characteristics to co-deliver the tumor-associated antigen polypeptide Trp-2 and the TLR4 agonist monophosphoryl lipid A (MPLA). To reduce immunosuppression in the tumor microenvironment, an immune checkpoint inhibitor, PD-L1 antagonist, was administrated along with PBAE nano-vaccines to delay melanoma development. We found that mannosylated Trp-2 and MPLA-loaded PBAE nano-vaccines can target and mature DCs, consequently boosting antigen-specific cytotoxic T lymphocyte activity against melanoma. The prophylactic study indicates that combination therapy with PD-L1 antagonist further enhanced anti-tumor efficacy by 3.7-fold and prolonged median survival time by 1.6-fold more than free Trp-2/MPLA inoculation. DC-targeting PBAE polymers have a great potential as a nanotechnology platform to design vaccines and achieve synergistic anti-tumor effects with immune checkpoint therapy.

Vaccination with nanoparticles combined with micro-adjuvants protects against cancer

BACKGROUND

Induction of strong T cell responses, in particular cytotoxic T cells, is a key for the generation of efficacious therapeutic cancer vaccines which yet, remains a major challenge for the vaccine developing world. Here we demonstrate that it is possible to harness the physiological properties of the lymphatic system to optimize the induction of a protective T cell response. Indeed, the lymphatic system sharply distinguishes between nanoscale and microscale particles. The former reaches the fenestrated lymphatic system via diffusion, while the latter either need to be transported by dendritic cells or form a local depot.

METHODS

Our previously developed cucumber-mosaic virus-derived nanoparticles termed (CuMV_TT-VLPs) incorporating a universal Tetanus toxoid epitope TT830-843 were assessed for their draining kinetics using stereomicroscopic imaging. A nano-vaccine has been generated by coupling p33 epitope as a model antigen to CuMV_TT-VLPs using bio-orthogonal Cu-free click chemistry. The CuMV_TT-p33 nano-sized vaccine has been next formulated with the micron-sized microcrystalline tyrosine (MCT) adjuvant and the formed depot effect was studied using confocal microscopy and trafficking experiments. The immunogenicity of the nanoparticles combined with the micron-sized adjuvant was next assessed in an aggressive transplanted murine melanoma model. The obtained results were compared to other commonly used adjuvants such as B type CpGs and Alum.

RESULTS

Our results showed that CuMV_TT-VLPs can efficiently and rapidly drain into the lymphatic system due to their nano-size of ~ 30 nm. However, formulating the nanoparticles with the micron-sized MCT adjuvant of ~ 5 μM resulted in a local depot for the nanoparticles and a longer exposure time for the immune system. The preclinical nano-vaccine CuMV_TT-p33 formulated with the micron-sized MCT adjuvant has enhanced the specific T cell response in the stringent B16F10p33 murine melanoma model. Furthermore, the micron-sized MCT adjuvant was as potent as B type CpGs and clearly superior to the commonly used Alum adjuvant when total CD8⁺, specific p33 T cell response or tumour protection were assessed.

CONCLUSION

The combination of nano- and micro-particles may optimally harness the physiological properties of the lymphatic system. Since the nanoparticles are well defined virus-like particles and the micron-sized adjuvant MCT has been used for decades in allergen-specific desensitization, this approach may readily be translated to the clinic.