Epitope targeting with self-assembled peptide vaccines

Structure-guided design and evaluation of CRM197-scaffolded vaccine targeting GnRH for animal immunocastration

Immunocastration is a humane alternative to surgical castration for controlling population and estrous behaviors in animals. Gonadotropin-releasing hormone (GnRH), the pivotal initiating hormone of the hormonal cascade in mammals, is the optimal target for immunocastration vaccine development. Cognate antigen-mediated cross-linking of B cell receptors (BCRs) is a strong activation signal for B cells and is facilitated by repetitive surface organizations of antigens. In this study, we describe the structure-guided design of highly immunogenic chimeric proteins with variant numbers of GnRH peptide insertion by epitope grafting. Linear B-cell epitopes of cross-reacting material 197 (CRM197) were replaced with multiple copies of GnRH peptide, and the inserts were displayed on the surface of the designs while maintaining the overall folding of CRM197. Among the seven designs, TCG13, which carries 13 copies of GnRH peptide, was the most immunogenic, and its immunocastration efficacy was evaluated in male mice. Vaccination with the BFA03-adjuvanted TCG13 induced potent humoral immunity and reduced the serum testosterone concentration in mice. It could significantly decrease sperm quality and severely impair gonadal function and fertility. These results demonstrate that CRM197 holds great value as a scaffold for epitope presentation in peptide-based vaccine development and supports TCG13 as a promising vaccine candidate for animal immunocastration. KEY POINTS: • Provide a feasible way to design chimeric immunogen targeting GnRH by epitope grafting. • CRM197 can accommodate the insertion of multiple copies of heterologous epitope peptides. • Administration with the most immunogenic design led to effective immunocastration in male mice.

In vivo edited eosinophils reconcile antigen specific Th2 response and mitigate airway allergy

BACKGROUND

Improvement is needed in the remedies used to control Th2 polarization. Bioengineering approaches have modified immune cells that have immunosuppressive functions. This study aims to generate modified eosinophils (Meos) in vivo and use Meos to balance Th2 polarization and reduce airway allergy.

METHODS

A cell editor was constructed. The editor contained a peptide carrier, an anti-siglec F antibody, MHC II, ovalbumin, and LgDNA (DNA extracted from a probiotic, Lactobacillus rhamnosus GG). Which was designated as Cedit. Meos are eosinophils modified using Cedits. An airway Th2 polarization mouse model was established used to test the effect of Meos on suppressing airway allergy.

RESULTS

The Cedits remained physically and chemically stable in solution (pH7.2) for at least 96 h. Cedits specifically bound to eosinophils, which are designated as Meos. Meos produced programmed death ligand-1 (PD-L1); the latter induced antigen specific CD4+ T cell apoptosis. Administration of Cedits through nasal instillations generated Meos in vivo, which significantly reduced the frequency of antigen specific CD4+ T cells in the airways, and mitigated airway Th2 polarization.

CONCLUSIONS

We constructed Cedit, which could edit eosinophils into Meos in vivo. Meos could induce antigen specific CD4+ T cell apoptosis, and reconcile airway Th2 polarization.

Chimeric Antigen-LgDNA Nanoparticles Attenuate Airway Th2 Polarization

Introduction

The therapeutic efficacy for airway allergies needs to be improved. Th2 polarization is a primary pathological feature of airway allergies. We constructed chimeric antigen-LgDNA (Lactobacillus rhamnosus DNA) nanoparticles (CAP-NPs). The effects of CAP-NPs on reconciling airway Th2 polarization were tested.

Methods

In this study, disulfide bond-linked antigen-major histocompatibility complex II (MHC II)-LgDNA nanoparticles (NPs) were constructed and designated CAP-NPs. An airway Th2 polarization mouse model was established to test the effects of CAP-NPs on suppressing the Th2 response.

Results

The CAP-NP components of ovalbumin (OVA), major histocompatibility complex II (MHC II), and LgDNA were confirmed in a series of laboratory tests. The CAP-NPs remained stable at pH7.2 for at least 96 h. In in vitro experiments, CAP-NPs bound to the surface of OVA-specific CD4+ T cells, which resulted in apoptosis of the antigen-specific CD4+ T cells. Removal of any of the three components from the NPs abolished the induction of apoptosis of antigen specific CD4+ T cells. CAP-NPs increased the expression of lysine-specific demethylase 5A (KDM5A) in CD4+ T cells. Histone H3K9 and the gene promoter of caspase 8 were demethylated by KDM5A, which led to transcription and expression of the caspase 8 gene. Administration of CAP-NPs significantly alleviated experimental airway Th2 polarization through activating the caspase 8-apoptosis signaling pathway.

Discussion

In this paper, we constructed CAP-NPs that could induce antigen-specific CD4+ T cell apoptosis. Administration of CAP-NPs efficiently alleviated experimental airway Th2 polarization.

Next-Generation Vaccine Development with Nanomaterials: Recent Advances, Possibilities, and Challenges

Nanomaterials are becoming important tools for vaccine development owing to their tunable and adaptable nature. Unique properties of nanomaterials afford opportunities to modulate trafficking through various tissues, complement or augment adjuvant activities, and specify antigen valency and display. This versatility has enabled recent work designing nanomaterial vaccines for a broad range of diseases, including cancer, inflammatory diseases, and various infectious diseases. Recent successes of nanoparticle vaccines during the coronavirus disease 2019 (COVID-19) pandemic have fueled enthusiasm further. In this review, the most recent developments in nanovaccines for infectious disease, cancer, inflammatory diseases, allergic diseases, and nanoadjuvants are summarized. Additionally, challenges and opportunities for clinical translation of this unique class of materials are discussed.

Peptide-based supramolecular vaccine systems

Currently approved replication-competent and inactivated vaccines are limited by excessive reactogenicity and poor safety profiles, while subunit vaccines are often insufficiently immunogenic without co-administering exogenous adjuvants. Self-assembling peptide-, peptidomimetic-, and protein-based biomaterials offer a means to overcome these challenges through their inherent modularity, multivalency, and biocompatibility. As these scaffolds are biologically derived and present antigenic arrays reminiscent of natural viruses, they are prone to immune recognition and are uniquely capable of functioning as self-adjuvanting vaccine delivery vehicles that improve humoral and cellular responses. Beyond this intrinsic immunological advantage, the wide range of available amino acids allows for facile de novo design or straightforward modifications to existing sequences. This has permitted the development of vaccines and immunotherapies tailored to specific disease models, as well as generalizable platforms that have been successfully applied to prevent or treat numerous infectious and non-infectious diseases. In this review, we briefly introduce the immune system, discuss the structural determinants of coiled coils, β-sheets, peptide amphiphiles, and protein subunit nanoparticles, and highlight the utility of these materials using notable examples of their innate and adaptive immunomodulatory capacity. STATEMENT OF SIGNIFICANCE: Subunit vaccines have recently gained considerable attention due to their favorable safety profiles relative to traditional whole-cell vaccines; however, their reduced efficacy requires co-administration of reactogenic adjuvants to boost immune responses. This has led to collaborative efforts between engineers and immunologists to develop nanomaterial-based vaccination platforms that can elicit protection without deleterious side effects. Self-assembling peptidic biomaterials are a particularly attractive approach to this problem, as their structure and function can be controlled through primary sequence design and their capacity for multivalent presentation of antigens grants them intrinsic self-adjuvanticity. This review introduces the various architectures adopted by self-assembling peptides and discusses their application as modulators of innate and adaptive immunity.

Novel Approaches in the Inhibition of IgE-Induced Mast Cell Reactivity in Food Allergy

Allergy is an IgE-dependent type-I hypersensitivity reaction that can lead to life-threatening systemic symptoms such as anaphylaxis. In the pathogenesis of the allergic response, the common upstream event is the binding of allergens to specific IgE, inducing cross-linking of the high-affinity FcεRI on mast cells, triggering cellular degranulation and the release of histamine, proteases, lipids mediators, cytokines and chemokines with inflammatory activity. A number of novel therapeutic options to curb mast cell activation are in the pipeline for the treatment of severe allergies. In addition to anti-IgE therapy and allergen-specific immunotherapy, monoclonal antibodies targeted against several key Th2/alarmin cytokines (i.e. IL-4Rα, IL-33, TSLP), active modification of allergen-specific IgE (i.e. inhibitory compounds, monoclonal antibodies, de-sialylation), engagement of inhibitory receptors on mast cells and allergen-specific adjuvant vaccines, are new promising options to inhibit the uncontrolled release of mast cell mediators upon allergen exposure. In this review, we critically discuss the novel approaches targeting mast cells limiting allergic responses and the immunological mechanisms involved, with special interest on food allergy treatment.

Epitope-targeting platform for broadly protective influenza vaccines

Seasonal influenza vaccines are often ineffective because they elicit strain-specific antibody responses to mutation-prone sites on the hemagglutinin (HA) head. Vaccines that provide long-lasting immunity to conserved epitopes are needed. Recently, we reported a nanoparticle-based vaccine platform produced by solid-phase peptide synthesis (SPPS) for targeting linear and helical protein-based epitopes. Here, we illustrate its potential for building broadly protective influenza vaccines. Targeting known epitopes in the HA stem, neuraminidase (NA) active site, and M2 ectodomain (M2e) conferred 50-75% survival against 5LD50 influenza B and H1N1 challenge; combining stem and M2e antigens increased survival to 90%. Additionally, protein sequence and structural information were employed in tandem to identify alternative epitopes that stimulate greater protection; we report three novel HA and NA sites that are highly conserved in type B viruses. One new target in the HA stem stimulated 100% survival, highlighting the value of this simple epitope discovery strategy. A candidate influenza B vaccine targeting two adjacent HA stem sites led to >104-fold reduction in pulmonary viral load. These studies describe a compelling platform for building vaccines that target conserved influenza epitopes.

Contraceptive and molecular function of a novel recombinant vaccine based human leukemia inhibitory factor on Balb/c mice: An experimental in vivo study

The functional competence of leukemia inhibitory factor (LIF), as immunocontraceptive vaccine in mice, was investigated. Balb/c mice were divided into two groups of vaccinated and controls. The recombinant human LIF (rhLIF) protein and phosphate buffer saline was emulsified with Freund's adjuvant and injected into vaccinated and control groups, respectively. Theinhibition of implantation was evaluated in mice uterine. The concentration of secreted interferon-γ (IFN-γ) and interleukin (IL)-4 were measured in cultured splenocyte of mice stimulated by rhLIF. The expressions of immune responsive gene 1 (IRG-1), cochlin (COCH), amphiregulin(Ar), and heparin-binding EGF-like growth factor (HB-EGF) genes were determined. Mice were assessed for inhibition of fertility after delivery, reversibility of immune response against rhLIF, and survival rate. Active immunization of mice with rhLIF resulted in reduction of the implantation and fertility rate up to 80.49% and 75%, respectively. All mice produced a high titer of anti-rhLIF antibodies in serums and vaginal fluids washes after 16 weeks; however, these antibodies were cleared from vaginal fluid washes after six months. A significant down-regulation in mRNA levels of IRG-1, Ar and HB-EGF was observed in vaccinated group compared to controls; however, no significant change in the expression profile of cochlin gene was detected. The results showed that rhLIF prevented pregnancy in a high percentage of female mice. Although the immunization of female Balb/c mice with rhLIF inhibited fertility and expression of genes associated with this molecule, further studies are needed to support this protein as a suitable candidate for contraceptive vaccine in mammals.

In Silico Prediction of Human Leukocytes Antigen (HLA) Class II Binding Hepatitis B Virus (HBV) Peptides in Botswana

Hepatitis B virus (HBV) is the primary cause of liver-related malignancies worldwide, and there is no effective cure for chronic HBV infection (CHB) currently. Strong immunological responses induced by T cells are associated with HBV clearance during acute infection; however, the repertoire of epitopes (epi) presented by major histocompatibility complexes (MHCs) to elicit these responses in various African populations is not well understood. In silico approaches were used to map and investigate 15-mers HBV peptides restricted to 9 HLA class II alleles with high population coverage in Botswana. Sequences from 44 HBV genotype A and 48 genotype D surface genes (PreS/S) from Botswana were used. Of the 1819 epi bindings predicted, 20.2% were strong binders (SB), and none of the putative epi bind to all the 9 alleles suggesting that multi-epitope, genotype-based, population-based vaccines will be more effective against HBV infections as opposed to previously proposed broad potency epitope-vaccines which were assumed to work for all alleles. In total, there were 297 unique epi predicted from the 3 proteins and amongst, S regions had the highest number of epi (n = 186). Epitope-densities (Depi) between genotypes A and D were similar. A number of mutations that hindered HLA-peptide binding were observed. We also identified antigenic and genotype-specific peptides with characteristics that are well suited for the development of sensitive diagnostic kits. This study identified candidate peptides that can be used for developing multi-epitope vaccines and highly sensitive diagnostic kits against HBV infection in an African population. Our results suggest that viral variability may hinder HBV peptide-MHC binding, required to initiate a cascade of immunological responses against infection.