An Overview of Recent Developments in the Application of Antigen Displaying Vaccine Platforms: Hints for Future SARS-CoV-2 VLP Vaccines

Recently, a great effort has been devoted to studying attenuated and subunit vaccine development against SARS-CoV-2 since its outbreak in December 2019. It is known that diverse virus-like particles (VLPs) are extensively employed as carriers to display various antigenic and immunostimulatory cargo modules for vaccine development. Single or multiple antigens or antigenic domains such as the spike or nucleocapsid protein or their variants from SARS-CoV-2 could also be incorporated into VLPs via either a genetic or chemical display approach. Such antigen display platforms would help screen safer and more effective vaccine candidates capable of generating a strong immune response with or without adjuvant. This review aims to provide valuable insights for the future development of SARS-CoV-2 VLP vaccines by summarizing the latest updates and perspectives on the vaccine development of VLP platforms for genetic and chemical displaying antigens from SARS-CoV-2.

Enhanced Osteogenesis Potential of MG-63 Cells through Sustained Delivery of VEGF via Liposomal Hydrogel

The challenges of using VEGF to promote osteoblastic differentiation include a short half-life and a narrow therapeutic window. A carrier system combining hydrogel and liposomes may improve the therapeutic efficacy of VEGF for bone regeneration. This study aimed to investigate the effects of delivery of VEGF via liposomal hydrogel on the osteogenesis of MG-63 cells. Liposomal hydrogel scaffold was fabricated and then characterized in terms of the morphological and chemical properties using FESEM and FTIR. In 2.5D analysis, the MG-63 cells were cultured on liposomal hydrogel + VEGF as the test group. The osteogenic effects of VEGF were compared with the control groups, i.e., hydrogel without liposomes + VEGF, osteogenic medium (OM) supplemented with a bolus of VEGF, and OM without VEGF. Cell morphology, viability, and differentiation and mineralization potential were investigated using FESEM, MTT assay, ALP activity, and Alizarin red staining. The characterization of scaffold showed no significant differences in the morphological and chemical properties between hydrogel with and without liposomes (p > 0.05). The final 2.5D culture demonstrated that cell proliferation, differentiation, and mineralization were significantly enhanced in the liposomal hydrogel + VEGF group compared with the control groups (p < 0.05). In conclusion, liposomal hydrogel can be used to deliver VEGF in a sustained manner in order to enhance the osteogenesis of MG-63 cells.

Peptide-Based Vaccine against Breast Cancer: Recent Advances and Prospects

Breast cancer is considered the second-leading cancer after lung cancer and is the most prevalent cancer among women globally. Currently, cancer immunotherapy via vaccine has gained great attention due to specific and targeted immune cell activity that creates a potent immune response, thus providing long-lasting protection against the disease. Despite peptides being very susceptible to enzymatic degradation and poor immunogenicity, they can be easily customized with selected epitopes to induce a specific immune response and particulate with carriers to improve their delivery and thus overcome their weaknesses. With advances in nanotechnology, the peptide-based vaccine could incorporate other components, thereby modulating the immune system response against breast cancer. Considering that peptide-based vaccines seem to show remarkably promising outcomes against cancer, this review focuses on and provides a specific view of peptide-based vaccines used against breast cancer. Here, we discuss the benefits associated with a peptide-based vaccine, which can be a mainstay in the prevention and recurrence of breast cancer. Additionally, we also report the results of recent trials as well as plausible prospects for nanotechnology against breast cancer.

New modular platform based on multi-adjuvanted amphiphilic chitosan nanoparticles for efficient lipopeptide vaccine delivery against group A streptococcus

An effective vaccine against group A streptococcus (GAS) is highly desirable for definitive control of GAS infections. In the present study, two variants of amphiphilic chitosan nanoparticles-based GAS vaccines were developed. The vaccines were primarily composed of encapsulated KLH protein (a source of T helper cell epitopes) and lipidated M-protein derived B cell peptide epitope (lipoJ14) within the amphiphilic structure of nanoparticles. The only difference between them was one of the nanoparticles vaccines received additional surface coating with poly (I:C). The formulated vaccines exhibited nanosized particles within the range of 220–240 nm. Cellular uptake study showed that nanoparticles vaccine without additional poly (I:C) coating has greater uptake by dendritic cells and macrophages compared to nanoparticles vaccine that was functionalized with poly (I:C). Both vaccines were found to be safe in mice and showed negligible cytotoxicity against HEK293 cells. Upon immunization in mice, both nanoparticle vaccines produced high antigen-specific antibodies titres that were regulated by a balanced Th1 and Th2 response compared to physical mixture. These antibodies elicited high opsonic activity against the tested GAS strains. Overall, our data demonstrated that amphiphilic chitosan nanoparticles platform induced a potent immune response even without additional inclusion of poly (I:C).

DENV-Mimetic Polymersome Nanoparticles Bearing Multi-Epitope Lipopeptides Antigen as the Next-Generation Dengue Vaccine

Dengue remains a severe threat to public health. The safety and efficacy of the licensed dengue vaccine is not clinically satisfactory, which necessitate the need of new approach in designing an effective dengue vaccine without eliciting adverse reaction. Herein, we have designed a lipidated multi-epitope peptide vaccine (LipoDV) that can elicit highly targeted humoral and cell-mediated immune responses. To improve its immunogenicity, LipoDV was presented on the surface of MPLA-functionalized polymersome nanoparticles (PNs-LipoDV-MPLA). The as-constructed vaccine delivery platform resembles the structural morphology of DENV owing to its spherical nanoscale particle size and surface immunostimulatory properties given by LipoDV and MPLA that emulating the functional role of DENV E and prM/M proteins respectively. A proof-of-concept study demonstrated that BALB/c mice immunized with PNs-LipoDV-MPLA induced a stronger antigen-specific antibody response with an enhanced cell-mediated immunity as characterized by the elevated IFN-γ secretion in comparison to other tested vaccine candidates which possess a lesser structural trait of DENV. The DENV-mimicking nanoparticles vaccine exhibited negligible toxicity as analyzed by hemolytic test, MTT assay, histopathological examination and abnormal toxicity test on immunized mice. Collectively, our study provides a strong foundation in designing an effective peptide-based vaccine delivery platform against DENV infection.

HER2/neu-Based Peptide Vaccination-Pulsed with B-Cell Epitope Induced Efficient Prophylactic and Therapeutic Antitumor Activities in TUBO Breast Cancer Mice Model

Breast cancer is the most common invasive cancer diagnosed among women. A cancer vaccine has been recognized as a form of immunotherapy with a prominent position in the prevention and treatment of breast cancer. The majority of current breast cancer vaccination strategies aim to stimulate antitumor T-cell responses of the HER2/neu oncogene, which is abnormally expressed in breast cancer cells. However, the role of the B-cell humoral response is often underappreciated in the cancer vaccine design. We have advanced this idea by elucidating the role of B-cells in cancer vaccination by designing a chimeric antigenic peptide possessing both cytotoxic T lymphocytes (GP2) and B-cell (P4) peptide epitopes derived from HER2/neu. The chimeric peptide (GP2-P4) was further conjugated to a carrier protein (KLH), forming a KLH-GP2-P4 conjugate. The immunogenicity of KLH-GP2-P4 was compared with KLH-GP2 (lacking the B-cell epitope) in BALB/c mice. Mice immunized with KLH-GP2-P4 elicited more potent antigen-specific neutralizing antibodies against syngeneic TUBO cells (cancer cell line overexpressing HER2/neu) that was governed by a balanced Th1/Th2 polarization in comparison to KLH-GP2. Subsequently, these immune responses led to greater inhibition of tumor growth and longer survival in TUBO tumor-bearing mice in both prophylactic and therapeutic challenge experiments. Overall, our data demonstrated that the B-cell epitope has a profound effect in orchestrating an efficacious antitumor immunity. Thus, a multi-epitope peptide vaccine encompassing cytotoxic T-lymphocytes, T-helper and B-cell epitopes represents a promising strategy in developing cancer vaccines with a preventive and therapeutic modality for the effective management of breast cancer.

Gelatin Hydrogels Loaded with Lactoferrin-Functionalized Bio-Nanosilver as a Potential Antibacterial and Anti-Biofilm Dressing for Infected Wounds: Synthesis, Characterization, and Deciphering of Cytotoxicity

Gelatin hydrogels are attractive for wound applications owing to their well-defined structural, physical, and chemical properties as well as good cell adhesion and biocompatibility. This study aimed to develop gelatin hydrogels incorporated with bio-nanosilver functionalized with lactoferrin (Ag-LTF) as a dual-antimicrobial action dressing, to be used in treating infected wounds. The hydrogels were cross-linked using genipin prior to loading with Ag-LTF and characterized for their physical and swelling properties, rheology, polymer and actives interactions, and in vitro release of the actives. The hydrogel's anti-biofilm and antibacterial performances against S. aureus and P. aeruginosa as well as their cytotoxicity effects were assessed in vitro, including primary wound healing gene expression of human dermal fibroblasts (HDFs). The formulated hydrogels showed adequate release of AgNPs and LTF, with promising antimicrobial effects against both bacterial strains. The Ag-LTF-loaded hydrogel did not significantly interfere with the normal cellular functions as no alteration was detected for cell viability, migration rate, and expression of the target genes, suggesting the nontoxicity of Ag-LTF as well as the hydrogels. In conclusion, Ag-LTF-loaded genipin-cross-linked gelatin hydrogel was successfully synthesized as a new approach for fighting biofilms in infected wounds, which may be applied to accelerate healing of chronic wounds.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Antimicrobial activity of multifaceted lactoferrin or graphene oxide functionalized silver nanocomposites biosynthesized using mushroom waste and chitosan

Hybrid nanoparticles designed to exert multiple mechanisms of antibacterial action offer a new approach to the fight against pathogenic resistant bacteria. In this study, nanomaterials with the dual actions of antibacterial and anti-biofilm activities were developed using silver nanoparticles (AgNPs) functionalized with either lactoferrin (LTF) or graphene oxide (GO). AgNPs were synthesized using mushroom waste as a reducing agent and chitosan (CS) as a stabilizing agent, prior to their surface functionalization with either GO (AgGO) or LTF (Ag-LTF). The AgNPs exhibited a surface plasmon resonance (SPR) band at 430 nm, as determined by UV-vis spectroscopy, whereas the absorption of AgGO and Ag-LTF occurred at 402 and 441 nm, respectively. Particle size analysis of AgNPs, AgGO, and Ag-LTF revealed sizes of 121.5 ± 10.5, 354.0 ± 1.6, and 130.8 ± 1.2 nm, respectively. All AgNPs, Ag-LTF, and AgGO inhibited selected Gram-positive bacteria and Gram-negative bacteria with comparable antibacterial performance, as determined by the agar diffusion method. Despite the absence of antibacterial activity by GO and LTF, a synergistic effect of AgGO and Ag-LTF was observed as they had a greater activity against P. aeruginosa. Moreover, Ag-LTF did not affect cell viability and migration rate of cells, suggesting the non-toxicity of Ag-LTF. In conclusion, AgNPs, Ag-LTF, and AgGO possess antibacterial activity, which may offer an alternative for future antibacterial agents.

Biosynthesis of multifaceted silver nanoparticles using waste mushroom and chitosan.

Towards the Development of Synthetic Antibiotics: Designs Inspired by Natural Antimicrobial Peptides

Virtually every living organism produces gene-encoded antimicrobial peptides (AMPs) that provide an immediate defence against pathogen invasion. Many AMPs have been isolated and used as antibiotics that are effective against multidrug-resistant bacteria. Although encouraging, AMPs have such poor drug-like properties that their application for clinical use is restricted. In turn, this has diverted research to the development of synthetic molecules that retain the therapeutic efficacy of AMPs but are endowed with greater biological stability and safety profiles. Most of the synthetic molecules, either based on a peptidic or non-peptidic scaffold, have been designed to mimic the amphiphilic properties of native AMPs, which are widely believed to be the key determinant of their antibacterial activity. In this review, the structural, chemical and biophysical features that govern the biological activities of various synthetic designs are discussed extensively. Recent innovative approaches from the literature that exhibit novel concepts towards the development of new synthetic antibacterial agents, including the engineered delivery platform incorporated with AMP mimetics, are also emphasised.

Comparison of Fluorinated and Nonfluorinated Lipids in Self-Adjuvanting Delivery Systems for Peptide-Based Vaccines

Safe immunostimulants (adjuvants) are essential for the development of highly potent peptide-based vaccines. This study examined for the first time whether fluorinated lipids could stimulate humoral immunity in vivo when conjugated to peptide antigen. The impact of fluorination on humoral immunity was tested using a library of peptide-based vaccine candidates against the group A streptococcus (GAS). The fluorinated constructs stimulated similar mouse IgG titers to those elicited by complete Freund's adjuvant (CFA) and were higher than those produced in mice that received the nonfluorinated constructs.

Short cationic lipopeptides as effective antibacterial agents: Design, physicochemical properties and biological evaluation

The spread of drug-resistant bacteria has imparted a sense of urgency in the search for new antibiotics. In an effort to develop a new generation of antibacterial agents, we have designed de novo charged lipopeptides inspired by natural antimicrobial peptides. These short lipopeptides are composed of cationic lysine and hydrophobic lipoamino acids that replicate the amphiphilic properties of natural antimicrobial peptides. The resultant lipopeptides were found to self-assemble into nanoparticles. Some were effective against a variety of Gram-positive bacteria, including strains resistant to methicillin, daptomycin and/or vancomycin. The lipopeptides were not toxic to human kidney and liver cell lines and were highly resistant to tryptic degradation. Transmission electron microscopy analysis of bacteria cells treated with lipopeptide showed membrane-damage and lysis with extrusion of cytosolic contents. With such properties in mind, these lipopeptides have the potential to be developed as new antibacterial agents against drug-resistant Gram-positive bacteria.

Self-assembling lipopeptides with a potent activity against Gram-positive bacteria, including multidrug resistant strains

Aim: To explore the potential of de novo designed cyclic lipopeptides and its linear counterparts as antibacterial agents. Materials & methods: The lipopeptides were synthesized via solid-phase peptide synthesis and the cyclization was achieved by using succinic acid linker. The antimicrobial activities of the lipopeptides were evaluated in vitro against a variety selection of Gram-negative and Gram-positive bacteria including clinical isolates of multidrug-resistant strains. Results: The synthesized lipopeptides were able to self-assemble into nanoparticles in an aqueous environment, with three exhibiting potent antibacterial activity against Gram-positive bacteria, including clinically relevant multidrug-resistant bacteria. Conclusion: The lead compounds have the potential to be developed as new antibacterials that are effective against Gram-positive bacteria, including multidrug-resistant isolates.

Self-adjuvanting vaccine against group A streptococcus: application of fibrillized peptide and immunostimulatory lipid as adjuvant

Peptides are of great interest to be used as vaccine antigens due to their safety, ease of manufacturing and specificity in generating immune response. There have been massive discoveries of peptide antigens over the past decade. However, peptides alone are poorly immunogenic, which demand co-administration with strong adjuvant to enhance their immunogenicity. Recently, fibril-forming peptides such as Q11 and lipoamino acid-based carrier have been identified to induce substantial immune responses when covalently linked to peptide epitope. In this study, we have incorporated either Q11 or lipoamino acids to a peptide epitope (J14) derived from M protein of group A streptococcus to develop self-adjuvanting vaccines. J14, Q11 and lipoamino acids were also conjugated together in a single vaccine construct in an attempt to evaluate the synergy effect of combining multiple adjuvants. Physicochemical characterization demonstrated that the vaccine constructs folded differently and self-assembled into nanoparticles. Significantly, only vaccine constructs containing double copies of lipoamino acids (regardless in conjugation with Q11 or not) were capable to induce significant dendritic cells uptake and subsequent J14-specific antibody responses in non-sizes dependent manners. Q11 had minimal impact in enhancing the immunogenicity of J14 even when it was used in combination with lipoamino acids. These findings highlight the impact of lipoamino acids moiety as a promising immunostimulant carrier and its number of attachment to peptide epitope was found to have a profound effect on the vaccine immunogenicity.

Recent progress in adjuvant discovery for peptide-based subunit vaccines

Peptide-based subunit vaccines are of great interest in modern immunotherapy as they are safe, easy to produce and well defined. However, peptide antigens produce a relatively weak immune response, and thus require the use of immunostimulants (adjuvants) for optimal efficacy. Developing a safe and effective adjuvant remains a challenge for peptide-based vaccine design. Recent advances in immunology have allowed researchers to have a better understanding of the immunological implication of related diseases, which facilitates more rational design of adjuvant systems. Understanding the molecular structure of the adjuvants allows the establishment of their structure-activity relationships which is useful for the development of next-generation adjuvants. This review summarizes the current state of adjuvants development in the field of synthetic peptide-based vaccines. The structural, chemical and biological properties of adjuvants associated with their immunomodulatory effects are discussed.