Surface conjugation of EP67 to biodegradable nanoparticles increases the generation of long-lived mucosal and systemic memory T-cells by encapsulated protein vaccine after respiratory immunization and subsequent T-cell-mediated protection against respiratory infection

Surface Bio-engineered Polymeric Nanoparticles

Surface bio-engineering of polymeric nanoparticles (PNPs) has emerged as a cornerstone in contemporary biomedical research, presenting a transformative avenue that can revolutionize diagnostics, therapies, and drug delivery systems. The approach involves integrating bioactive elements on the surfaces of PNPs, aiming to provide them with functionalities to enable precise, targeted, and favorable interactions with biological components within cellular environments. However, the full potential of surface bio-engineered PNPs in biomedicine is hampered by obstacles, including precise control over surface modifications, stability in biological environments, and lasting targeted interactions with cells or tissues. Concerns like scalability, reproducibility, and long-term safety also impede translation to clinical practice. In this review, these challenges in the context of recent breakthroughs in developing surface-biofunctionalized PNPs for various applications, from biosensing and bioimaging to targeted delivery of therapeutics are discussed. Particular attention is given to bonding mechanisms that underlie the attachment of bioactive moieties to PNP surfaces. The stability and efficacy of surface-bioengineered PNPs are critically reviewed in disease detection, diagnostics, and treatment, both in vitro and in vivo settings. Insights into existing challenges and limitations impeding progress are provided, and a forward-looking discussion on the field's future is presented. The paper concludes with recommendations to accelerate the clinical translation of surface bio-engineered PNPs.

Surface Modification of Biodegradable Microparticles with the Novel Host-Derived Immunostimulant CPDI-02 Significantly Increases Short-Term and Long-Term Mucosal and Systemic Antibodies against Encapsulated Protein Antigen in Young Naïve Mice after Respiratory Immunization

Generating long-lived mucosal and systemic antibodies through respiratory immunization with protective antigens encapsulated in nanoscale biodegradable particles could potentially decrease or eliminate the incidence of many infectious diseases, but requires the incorporation of a suitable mucosal immunostimulant. We previously found that respiratory immunization with a model protein antigen (LPS-free OVA) encapsulated in PLGA 50:50 nanoparticles (~380 nm diameter) surface-modified with complement peptide-derived immunostimulant 02 (CPDI-02; formerly EP67) through 2 kDa PEG linkers increases mucosal and systemic OVA-specific memory T-cells with long-lived surface phenotypes in young, naïve female C57BL/6 mice. Here, we determined if respiratory immunization with LPS-free OVA encapsulated in similar PLGA 50:50 microparticles (~1 μm diameter) surface-modified with CPDI-02 (CPDI-02-MP) increases long-term OVA-specific mucosal and systemic antibodies. We found that, compared to MP surface-modified with inactive, scrambled scCPDI-02 (scCPDI-02-MP), intranasal administration of CPDI-02-MP in 50 μL sterile PBS greatly increased titers of short-term (14 days post-immunization) and long-term (90 days post-immunization) antibodies against encapsulated LPS-free OVA in nasal lavage fluids, bronchoalveolar lavage fluids, and sera of young, naïve female C57BL/6 mice with minimal lung inflammation. Thus, surface modification of ~1 μm biodegradable microparticles with CPDI-02 is likely to increase long-term mucosal and systemic antibodies against encapsulated protein antigen after respiratory and possibly other routes of mucosal immunization.

Applications of nanoengineered therapeutics and vaccines: special emphasis on COVID-19

Nanomedicine provides innovative strategies that had significantly improved drug and gene delivery and allowed control over the engineering of therapeutics, diagnostics, vaccines, and other medical devices, for a diversity of medical applications. This review focuses on the current attempts to develop potent nanoengineered vaccines and therapeutics against coronaviruses, and the recent fabrication strategies and design principles to control acute infections from the escalating SARS-CoV-2 pandemic. Nanomedical approaches provide versatile platforms that can be utilized to enhance the overall potency, safety, and stability of vaccines, thus augmenting the desired immune response. Their modulable conformational features of size, shape, surface charge, antigen display, and composition allow for precise tuning and optimization of the nanoconstructs for the management of a variety of diseases and pathological conditions. The ability to control the release of their encapsulated cargoes and the possibility of surface decoration with various moieties support the construction of multifunctional nanomaterials that ultimately boost and prolong the immune response elicited and/or therapeutic effects, selectively at the diseased tissues and target sites.

Innovative vaccine platforms against infectious diseases: Under the scope of the COVID-19 pandemic

While classic vaccines have proved greatly efficacious in eliminating serious infectious diseases, innovative vaccine platforms open a new pathway to overcome dangerous pandemics via the development of safe and effective formulations. Such platforms play a key role either as antigen delivery systems or as immune-stimulators that induce both innate and adaptive immune responses. Liposomes or lipid nanoparticles, virus-like particles, nanoemulsions, polymeric or inorganic nanoparticles, as well as viral vectors, all belong to the nanoscale and are the main categories of innovative vaccines that are currently on the market or in clinical and preclinical phases. In this paper, we review the above formulations used in vaccinology and we discuss their connection with the development of safe and effective prophylactic vaccines against SARS-CoV-2.

Co-assembled nanocomplexes of peptide neoantigen Adpgk and Toll-like receptor 9 agonist CpG ODN for efficient colorectal cancer immunotherapy

Cancer vaccines targeting tumor specific neoantigens derived from nonsynonymous mutations of tumor cells have emerged as an effective approach to induce antitumor T cells responses for personalized cancer immunotherapy. Despite the enormous potential of synthetic peptides as a common modality for neoantigen vaccines, their practical efficacy was limited due to their relatively low immunogenicity. Herein, we modify neoantigen peptide (Adpgk) derived from MC-38 colon carcinoma by supplementing ten consecutive positively-charged lysines (10 K-Adpgk) to obtain cationic polypeptide. And then we made them self-assemble with toll-like receptor 9 (TLR-9) agonist CpG oligodeoxynucleotides (CpG ODN) adjuvant directly forming antigen/adjuvant integrated nanocomplexes (PCNPs) through electrostatic interaction for potent tumor immunotherapy. The optimal formed PCNPs were around 175 nm with uniform size distribution and could maintain stability in physiological saline solution. CpG ODN and 10 K-Adpgk in the formed PCNPs could be effectively uptake by dendritic cells (DCs) and stimulate the maturation of DCs as well as improving the efficiency of antigen cross-presentation efficiency in vitro. Furthermore, the PCNPs vaccine could markedly improve neoantigen and adjuvant co-delivery efficiency to lymphoid organs and activate cytotoxic T cells. In addition, vaccination with PCNPs could not only offer prophylactic to protect mice from challenged MC-38 colorectal tumors, but also achieve a better anti-tumor effect in an established colorectal tumor model, and significantly prolong the survival rate of tumor-bearing mice. Therefore, this work provided a versatile but effective method for neoantigen peptide and CpG ODN co-assembly vaccine platform for efficient colorectal cancer immunotherapy.

A novel self-assembled epitope peptide nanoemulsion vaccine targeting nasal mucosal epithelial cell for reinvigorating CD8+ T cell immune activity and inhibiting tumor progression

Epitope peptides are not suitable for nasal administration immunity due to their poor immunogenicity and low delivery efficiency. Here, we reported an intranasal self-assembled nanovaccine (I-OVA NE), which was loaded with the peptides IKVAV-OVA_257-264 (I-OVA), a laminin peptide (Ile-Lys-Val-ala-Val, IKVAV) and OVA_257-264 epitope conjugated peptide. This nanovaccine with I-OVA at a concentration of 4 mg/mL showed the average particle size of 30.37 ± 2.49 nm, zeta potential of -16.67 ± 1.76 mV, and encapsulation rate of 84.07 ± 7.59%. Moreover, the mucin did not alter its stability (size, PdI and zeta potential). And it also had no obvious acute pathological changes neither in the nasal mucosa nor lung tissues after nasal administration. Meanwhile, the antigen uptake of I-OVA NE was promoted, and the nasal residence time was also prolonged in vivo. Besides, the uptake rate of this nanovaccine was obviously higher than that of free I-OVA (P < 0.001) after blocking by the integrin antibody, suggesting that the binding of IKVAV to integrin is involved in the epitope peptide uptake. Importantly, this nanovaccine enhanced peptide-specific CD8⁺T cells exhibiting OVA_257-264-specific CTL activity and Th1 immune response, leading to the induction of the protective immunity in E.G7-OVA tumor-bearing mice. Overall, these data indicate that I-OVA NE can be an applicable strategy of tumor vaccine development.

Targeted Amino Acid Substitution Overcomes Scale-Up Challenges with the Human C5a-Derived Decapeptide Immunostimulant EP67

EP67 is a second-generation, human C5a-derived decapeptide agonist of C5a receptor 1 (C5aR1/CD88) that selectively activates mononuclear phagocytes over neutrophils to potentiate protective innate and adaptive immune responses while potentially minimizing neutrophil-mediated toxicity. Pro7 and N-methyl-Leu8 (Me-Leu8) amino acid residues within EP67 likely induce backbone structural changes that increase potency and selective activation of mononuclear phagocytes over neutrophils versus first-generation EP54. The low coupling efficiency between Pro7 and Me-Leu8 and challenging purification by HPLC, however, greatly increase scale-up costs of EP67 for clinical use. Thus, the goal of this study was to determine whether replacing Pro7 and/or Me-Leu8 with large-scale amenable amino acid residues predicted to induce similar structural changes (cyclohexylalanine7 and/or leucine8) sufficiently preserves EP67 activity in primary human mononuclear phagocytes and neutrophils. We found that EP67 analogues had similar potency, efficacy, and selective activation of mononuclear phagocytes over neutrophils. Thus, replacing Pro7 and/or Me-Leu8 with large-scale amenable amino acid residues predicted to induce similar structural changes is a suitable strategy to overcome scale-up challenges with EP67.