Respiratory mucosal vaccination of peptide-poloxamine-DNA nanoparticles provides complete protection against lethal SARS-CoV-2 challenge

Recent Progress in Nucleic Acid Pulmonary Delivery toward Overcoming Physiological Barriers and Improving Transfection Efficiency

Pulmonary delivery of therapeutic agents has been considered the desirable administration route for local lung disease treatment. As the latest generation of therapeutic agents, nucleic acid has been gradually developed as gene therapy for local diseases such as asthma, chronic obstructive pulmonary diseases, and lung fibrosis. The features of nucleic acid, specific physiological structure, and pathophysiological barriers of the respiratory tract have strongly affected the delivery efficiency and pulmonary bioavailability of nucleic acid, directly related to the treatment outcomes. The development of pharmaceutics and material science provides the potential for highly effective pulmonary medicine delivery. In this review, the key factors and barriers are first introduced that affect the pulmonary delivery and bioavailability of nucleic acids. The advanced inhaled materials for nucleic acid delivery are further summarized. The recent progress of platform designs for improving the pulmonary delivery efficiency of nucleic acids and their therapeutic outcomes have been systematically analyzed, with the application and the perspectives of advanced vectors for pulmonary gene delivery.

Enhancement of SARS-CoV-2 mRNA Vaccine Efficacy through the Application of TMSB10 UTR for Superior Antigen Presentation and Immune Activation

The development of effective vaccines against SARS-CoV-2 remains a critical challenge amidst the ongoing global pandemic. This study introduces a novel approach to enhancing mRNA vaccine efficacy by leveraging the untranslated region (UTR) of TMSB10, a gene identified for its significant mRNA abundance in antigen-presenting cells. Utilizing the GEO database, we identified TMSB10 among nine genes, with the highest mRNA abundance in dendritic cell subtypes. Subsequent experiments revealed that TMSB10's UTR significantly enhances the expression of a reporter gene in both antigen-presenting and 293T cells, surpassing other candidates and a previously optimized natural UTR. A comparative analysis demonstrated that TMSB10 UTR not only facilitated a higher reporter gene expression in vitro but also showed marked superiority in vivo, leading to enhanced specific humoral and cellular immune responses against the SARS-CoV-2 Delta variant RBD antigen. Specifically, vaccines incorporating TMSB10 UTR induced significantly higher levels of specific IgG antibodies and promoted a robust T-cell immune response, characterized by the increased secretion of IFN-γ and IL-4 and the proliferation of CD4+ and CD8+ T cells. These findings underscore the potential of TMSB10 UTR as a strategic component in mRNA vaccine design, offering a promising avenue to bolster vaccine-induced immunity against SARS-CoV-2 and, potentially, other pathogens.

Intranasal G5-BGG/pDNA Vaccine Elicits Protective Systemic and Mucosal Immunity against SARS-CoV-2 by Transfecting Mucosal Dendritic Cells

Infectious disease pandemics, including the coronavirus disease 2019 pandemic, have heightened the demand for vaccines. Although parenteral vaccines induce robust systemic immunity, their effectiveness in respiratory mucosae is limited. Considering the crucial role of nasal-associated lymphoid tissue (NALT) in mucosal immune responses, in this study, the intranasal complex composed of G5-BGG and antigen-expressing plasmid DNA (pSP), named G5-BGG/pSP complex, is developed to activate NALT and to promote both systemic and mucosal immune defense. G5-BGG/pSP could traverse mucosal barriers and deliver DNA to the target cells because of its superior nasal retention and permeability characteristics. The intranasal G5-BGG/pSP complex elicits robust antigen-specific immune responses, such as the notable production of IgG antibody against several virus variants. More importantly, it induces elevated levels of antigen-specific IgA antibody and a significant expansion of the lung-resident T lymphocyte population. Notably, the intranasal G5-BGG/pSP complex results in antigen expression and maturation of dendritic cells in nasal mucosae. These findings exhibit the potential of G5-BGG, a novel cationic material, as an effective gene carrier for intranasal vaccines to obtain robust systemic and mucosal immunity.

Unmasking the potential of secretory IgA and its pivotal role in protection from respiratory viruses

Mucosal immunity has regained its spotlight amidst the ongoing Coronavirus disease 19 (COVID-19) pandemic, with numerous studies highlighting the crucial role of mucosal secretory IgA (SIgA) in protection against Severe acute respiratory syndrome coronavirus-2 or SARS-CoV-2 infections. The observed limitations in the efficacy of currently authorized COVID-19 vaccines in inducing effective mucosal immune responses remind us of the limitations of systemic vaccination in promoting protective mucosal immunity. This resurgence of interest has motivated the development of vaccine platforms capable of enhancing mucosal responses, specifically the SIgA response, and the development of IgA-based therapeutics. Recognizing viral respiratory infections as a global threat, we would like to comprehensively review the existing knowledge on mucosal immunity, with a particular emphasis on SIgA, in the context of SARS-CoV-2, influenza, and Respiratory Syncytial Virus (RSV) infections. This review aims to describe the structural and functional specificities of SIgA, along with its nuanced role in combating influenza, RSV, and SARS-CoV-2 infections. Subsequent sections further elaborate promising vaccine strategies, including mucosal vaccines against Influenza, RSV, and SARS-CoV-2 respiratory viruses, currently undergoing preclinical and clinical development. Additionally, we address the challenges associated with mucosal vaccine development, concluding with a discussion on IgA-based therapeutics as a promising platform for the treatment of viral respiratory infections. This comprehensive review not only synthesizes current insights into mucosal immunity but also identifies critical knowledge gaps, strengthening the way for further advancements in our current understanding and approaches to combat respiratory viral threats.

Intravenous Senescent Erythrocyte Vaccination Modulates Adaptive Immunity and Splenic Complement Production

Targeted delivery of vaccines to the spleen remains a challenge. Inspired by the erythrophagocytotic process in the spleen, we herein report that intravenous administration of senescent erythrocyte-based vaccines profoundly alters their tropism toward splenic antigen-presenting cells (APCs) for imprinting adaptive immune responses. Compared with subcutaneous inoculation, intravenous vaccination significantly upregulated splenic complement expression in vivo and demonstrated synergistic antibody killing in vitro. Consequently, intravenous senescent erythrocyte vaccination produces potent SARS-CoV-2 antibody-neutralizing effects, with potential protective immune responses. Moreover, the proposed senescent erythrocyte can deliver antigens from resected tumors and adjuvants to splenic APCs, thereby inducing a personalized immune reaction against tumor recurrence after surgery. Hence, our findings suggest that senescent erythrocyte-based vaccines can specifically target splenic APCs and evoke adaptive immunity and complement production, broadening the tools for modulating immunity, helping to understand adaptive response mechanisms to senescent erythrocytes better, and developing improved vaccines against cancer and infectious diseases.

Nanovaccines for Advancing Long-Lasting Immunity against Infectious Diseases

Infectious diseases, particularly life-threatening pathogens such as small pox and influenza, have substantial implications on public health and global economies. Vaccination is a key approach to combat existing and emerging pathogens. Immunological memory is an essential characteristic used to evaluate vaccine efficacy and durability and the basis for the long-term effects of vaccines in protecting against future infections; however, optimizing the potency, improving the quality, and enhancing the durability of immune responses remains challenging and a focus for research involving investigation of nanovaccine technologies. In this review, we describe how nanovaccines can address the challenges for conventional vaccines in stimulating adaptive immune memory responses to protect against reinfection. We discuss protein and nonprotein nanoparticles as useful antigen platforms, including those with highly ordered and repetitive antigen array presentation to enhance immunogenicity through cross-linking with multiple B cell receptors, and with a focus on antigen properties. In addition, we describe how nanoadjuvants can improve immune responses by providing enhanced access to lymph nodes, lymphnode targeting, germinal center retention, and long-lasting immune response generation. Nanotechnology has the advantage to facilitate vaccine induction of long-lasting immunity against infectious diseases, now and in the future.

Mucosal SARS-CoV-2 Nanoparticle Vaccine Based on Mucosal Adjuvants and Its Immune Effectiveness by Intranasal Administration

SARS-CoV-2 is a respiratory virus that causes significant threats to human health. Mucosal immunity provides a first-line defense to prevent the infection of SARS-CoV-2 in the respiratory tract. Because most SARS-CoV-2 vaccines could not stimulate mucosal immunity in the respiratory tract, appropriate mucosal adjuvants or delivery systems are needed for mucosal vaccine development. Mannan, polyarginine, and 2',3'-cGAMP are three mucosal adjuvants that could stimulate mucosal immunity. In the present study, the three adjuvants were assembled with a receptor-binding domain (RBD) by electrostatic interaction to generate a nanoparticle vaccine (RBD-MP-cG). RBD-MP-cG elicited mucosal IgA and IgG response in bronchoalveolar lavage and nasal lavage by intranasal administration. It induced a robust RBD-specific antibody response, high levels of protective neutralizing antibody, and ACE2-blocking activity in the mouse sera. It stimulated the splenic secretion of high levels of Th1-, Th2-, and Th17-type cytokines. Thus, RBD-MP-cG elicited strong mucosal immunity and systematic immunity by intranasal administration. RBD-MP-cG was expected to act as a safe, effective, and easily produced mucosal nanoparticle vaccine to combat the infection of SARS-CoV-2.

FOF1-ATPase Motor-Embedded Chromatophore as Drug Delivery System: Extraction, Cargo Loading Ability and Mucus Penetration Ability

Mucosal drug delivery permits direct and prompt drug absorption, which is capable of reducing undesirable decomposition that occurs before absorption. However, mucus clearance of those mucosal drug delivery systems strongly retards their actual application. Herein, we propose chromatophore nanoparticles embedded with FOF1-ATPase motors to promote mucus penetration. The FOF1-ATPase motor-embedded chromatophores were firstly extracted from Thermus thermophilus by using a gradient centrifugation method. Then, the model drug (curcumin) was loaded onto the chromatophores. The drug loading efficiency and entrapment efficiency were optimized by using different loading approaches. The activity, motility, stability and mucus permeation of the drug-loaded chromatophore nanoparticles were thoroughly investigated. Both the in vitro and in vivo studies revealed that the FOF1-ATPase motor-embedded chromatophore successfully enhanced mucus penetration glioma therapy. This study indicates that the FOF1-ATPase motor-embedded chromatophore is a promising alternative as a mucosal drug delivery system.

Design and Immunogenicity of SARS-CoV-2 DNA Vaccine Encoding RBD-PVXCP Fusion Protein

The potential of immune-evasive mutation accumulation in the SARS-CoV-2 virus has led to its rapid spread, causing over 600 million confirmed cases and more than 6.5 million confirmed deaths. The huge demand for the rapid development and deployment of low-cost and effective vaccines against emerging variants has renewed interest in DNA vaccine technology. Here, we report the rapid generation and immunological evaluation of novel DNA vaccine candidates against the Wuhan-Hu-1 and Omicron variants based on the RBD protein fused with the Potato virus X coat protein (PVXCP). The delivery of DNA vaccines using electroporation in a two-dose regimen induced high-antibody titers and profound cellular responses in mice. The antibody titers induced against the Omicron variant of the vaccine were sufficient for effective protection against both Omicron and Wuhan-Hu-1 virus infections. The PVXCP protein in the vaccine construct shifted the immune response to the favorable Th1-like type and provided the oligomerization of RBD-PVXCP protein. Naked DNA delivery by needle-free injection allowed us to achieve antibody titers comparable with mRNA-LNP delivery in rabbits. These data identify the RBD-PVXCP DNA vaccine platform as a promising solution for robust and effective SARS-CoV-2 protection, supporting further translational study.