Preparation and characterization of microencapsulated DwPT trivalent vaccine using water soluble chitosan and its in-vitro and in-vivo immunological properties

The Role of Mucoadhesion and Mucopenetration in the Immune Response Induced by Polymer-Based Mucosal Adjuvants

Mucus is a viscoelastic gel that acts as a protective barrier for epithelial surfaces. The mucosal vehicles and adjuvants need to pass through the mucus layer to make drugs and vaccine delivery by mucosal routes possible. The mucoadhesion of polymer particle adjuvants significantly increases the contact time between vaccine formulations and the mucosa; then, the particles can penetrate the mucus layer and epithelium to reach mucosa-associated lymphoid tissues. This review presents the key findings that have aided in understanding mucoadhesion and mucopenetration while exploring the influence of physicochemical characteristics on mucus-polymer interactions. We describe polymer-based particles designed with mucoadhesive or mucopenetrating properties and discuss the impact of mucoadhesive polymers on local and systemic immune responses after mucosal immunization. In future research, more attention paid to the design and development of mucosal adjuvants could lead to more effective vaccines.

Fabrication of chitosan-coated epigallocatechin-3-gallate (EGCG)-hordein nanoparticles and their transcellular permeability in Caco-2/HT29 cocultures

Epigallocatechin-3-gallate (EGCG) has gained appreciable attention because of its health benefits. However, the poor permeability across the intestine limits its use. In this study, we have fabricated chitosan-coated EGCG-hordein nanoparticles (Cs-EHNs), with the aim to enhance the intestinal permeability of EGCG. Cs-EHNs were fabricated by layer-by-layer electrostatic stacking method, and its uptake and transcellular permeability were studied in the Caco-2/HT29 co-culture model. The constructed Cs-EHNs had the average diameter of 296 nm, polymer dispersity index (PDI) of 0.30, zeta potential of 59.6 mV, and showed a spherical morphology. Encapsulation efficiency of EGCG was 87.3%. The transcellular permeability experiments indicated that the apparent permeability coefficient (P_app) of Cs-EHNs was higher than that of free EGCG. Furthermore, the cellular uptake of Cs-EHNs was studied by specific endocytosis inhibitors, and results showed that the uptake mechanisms of Cs-EHNs were through caveolae-mediated endocytosis and macropinocytosis. This study demonstrated that encapsulation of EGCG using chitosan-coated hordein nanoparticles could be a promising approach to improve the absorption of EGCG.

Biomaterials and nanomaterials for sustained release vaccine delivery

Vaccines are considered one of the most significant medical advancements in human history, as they have prevented hundreds of millions of deaths since their discovery; however, modern travel permits disease spread at unprecedented rates, and vaccine shortcomings like thermal sensitivity and required booster shots have been made evident by the COVID-19 pandemic. Approaches to overcoming these issues appear promising via the integration of vaccine technology with biomaterials, which offer sustained-release properties and preserve proteins, prevent conformational changes, and enable storage at room temperature. Sustained release and thermal stabilization of therapeutic biomacromolecules is an emerging area that integrates material science, chemistry, immunology, nanotechnology, and pathology to investigate different biocompatible materials. Biomaterials, including natural sugar polymers, synthetic polyesters produced from biologically derived monomers, hydrogel blends, protein-polymer blends, and metal-organic frameworks, have emerged as early players in the field. This overview will focus on significant advances of sustained release biomaterial in the context of vaccines against infectious disease and the progress made towards thermally stable "single-shot" formulations. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

Mucosal Immunization Against Pertussis: Lessons From the Past and Perspectives

Background

Current vaccination strategies against pertussis are sub-optimal. Optimal protection against Bordetella pertussis, the causative agent of pertussis, likely requires mucosal immunity. Current pertussis vaccines consist of inactivated whole B. pertussis cells or purified antigens thereof, combined with diphtheria and tetanus toxoids. Although they are highly protective against severe pertussis disease, they fail to elicit mucosal immunity. Compared to natural infection, immune responses following immunization are short-lived and fail to prevent bacterial colonization of the upper respiratory tract. To overcome these shortcomings, efforts have been made for decades, and continue to be made, toward the development of mucosal vaccines against pertussis.

Objectives

In this review we systematically analyzed published literature on protection conferred by mucosal immunization against pertussis. Immune responses mounted by these vaccines are summarized.

Method

The PubMed Library database was searched for published studies on mucosal pertussis vaccines. Eligibility criteria included mucosal administration and the evaluation of at least one outcome related to efficacy, immunogenicity and safety.

Results

While over 349 publications were identified by the search, only 63 studies met the eligibility criteria. All eligible studies are included here. Initial attempts of mucosal whole-cell vaccine administration in humans provided promising results, but were not followed up. More recently, diverse vaccination strategies have been tested, including non-replicating and replicating vaccine candidates given by three different mucosal routes: orally, nasally or rectally. Several adjuvants and particulate formulations were tested to enhance the efficacy of non-replicating vaccines administered mucosally. Most novel vaccine candidates were only tested in animal models, mainly mice. Only one novel mucosal vaccine candidate was tested in baboons and in human trials.

Conclusion

Three vaccination strategies drew our attention, as they provided protective and durable immunity in the respiratory tract, including the upper respiratory tract: acellular vaccines adjuvanted with lipopeptide LP1569 and c-di-GMP, outer membrane vesicles and the live attenuated BPZE1 vaccine. Among all experimental vaccines, BPZE1 is the only one that has advanced into clinical development.

Biological properties the novel application of N-trimethyl chitosan nanospheres as a stabilizer and preservative in tetanus vaccine

Purpose

Chitosan is a natural polymer that has excellent properties include biocompatibility, biodegradability, no cytotoxicity, high charge density, low cost, mucoadhesive, permeation enhancing (ability to cross tight junction), and immunomodulating ability that makes the spectrum of its applicability much broader. This study was conducted to investigate the stabilizing, preservative and immunogenicity properties of N-trimethyl chitosan nanospheres (N-TMCNS).

Materials and Methods

The tetanus toxoid (TT) was encapsulated into N-TMCNS and then characterized by scanning electron microscope, atomic force microscope, and dynamic light scattering. For stabilizer assay of N-TMCNS after storage of TT-N-TMCNS at different temperatures for 3 weeks, they were used for immunization of mice and different temperatures groups' anti-TT-N-TMCNS production compared with other groups. Finally, the immunized mice were challenged with tetanus toxin. The preservation activity of TT-N-TMCNS against Escherichia coli was compared with thimerosal formulated TT.

Results

Our results revealed that heat-treated TT-N-TMCNS could induce higher titer of neutralizing immunoglobulin G in compared to TT vaccine and was able to protect the mice better than TT vaccine in challenge test. Furthermore, N-TMCNS as a preservative inhibited the growth of E. coli more effective than thimerosal.

Conclusion

Overall, the obtained results indicated that the N-TMCNS is one of the best stabilizer and preservative agent that can be used in the formulation of TT vaccine.

Current and New Approaches for Mucosal Vaccine Delivery

Mucosal surfaces are the interface between the host’s internal milieu and the external environment, and they have dual functions, serving as physical barriers to foreign antigens and as accepting sites for vital materials. Mucosal vaccines are more favored to prevent mucosal infections from the portal of entry. Although mucosal vaccination has many advantages, licensed mucosal vaccines are scarce. The most widely studied mucosal routes are oral and intranasal. Licensed oral and intranasal vaccines are composed mostly of whole cell killed or live attenuated microorganisms serving as both delivery systems and built-in adjuvants. Future mucosal vaccines should be made with more purified antigen components, which will be relatively less immunogenic. To induce robust protective immune responses against well-purified vaccine antigens, an effective mucosal delivery system is an essential requisite. Recent developments in biomaterials and nanotechnology have enabled many innovative mucosal vaccine trials. For oral vaccination, the vaccine delivery system should be able to stably carry antigens and adjuvants and resist harsh physicochemical conditions in the stomach and intestinal tract. Besides many nano/microcarrier tools generated by using natural and chemical materials, the development of oral vaccine delivery systems using food materials should be more robustly researched to expand vaccine coverage of gastrointestinal infections in developing countries. For intranasal vaccination, the vaccine delivery system should survive the very active mucociliary clearance mechanisms and prove safety because of the anatomical location of nasal cavity separated by a thin barrier. Future mucosal vaccine carriers, regardless of administration routes, should have certain common characteristics. They should maintain stability in given environments, be mucoadhesive, and have the ability to target specific tissues and cells.