Respiratory nanoparticle-based vaccines and challenges associated with animal models and translation

Nasal Delivery to the Brain: Harnessing Nanoparticles for Effective Drug Transport

The nose-to-brain drug-delivery system has emerged as a promising strategy to overcome the challenges associated with conventional drug administration for central nervous system disorders. This emerging field is driven by the anatomical advantages of the nasal route, enabling the direct transport of drugs from the nasal cavity to the brain, thereby circumventing the blood-brain barrier. This review highlights the significance of the anatomical features of the nasal cavity, emphasizing its high permeability and rich blood supply that facilitate rapid drug absorption and onset of action, rendering it a promising domain for neurological therapeutics. Exploring recent developments and innovations in different nanocarriers such as liposomes, polymeric nanoparticles, solid lipid nanoparticles, dendrimers, micelles, nanoemulsions, nanosuspensions, carbon nanotubes, mesoporous silica nanoparticles, and nanogels unveils their diverse functions in improving drug-delivery efficiency and targeting specificity within this system. To minimize the potential risk of nanoparticle-induced toxicity in the nasal mucosa, this article also delves into the latest advancements in the formulation strategies commonly involving surface modifications, incorporating cutting-edge materials, the adjustment of particle properties, and the development of novel formulations to improve drug stability, release kinetics, and targeting specificity. These approaches aim to enhance drug absorption while minimizing adverse effects. These strategies hold the potential to catalyze the advancement of safer and more efficient nose-to-brain drug-delivery systems, consequently revolutionizing treatments for neurological disorders. This review provides a valuable resource for researchers, clinicians, and pharmaceutical-industry professionals seeking to advance the development of effective and safe therapies for central nervous system disorders.

Nanomedicine at the Pulmonary Frontier: Immune-Centric Approaches for Respiratory Disease Treatment

Respiratory diseases (RD) are a group of common ailments with a rapidly increasing global prevalence, posing a significant threat to humanity, especially the elderly population, and imposing a substantial burden on society and the economy. RD represents an unmet medical need that requires the development of viable pharmacotherapies. While various promising strategies have been devised to advance potential treatments for RD, their implementation has been hindered by difficulties in drug delivery, particularly in critically ill patients. Nanotechnology offers innovative solutions for delivering medications to the inflamed organ sites, such as the lungs. Although this approach is enticing, delivering nanomedicine to the lungs presents complex challenges that require sophisticated techniques. In this context, we review the potential of novel nanomedicine-based immunomodulatory strategies that could offer therapeutic benefits in managing this pressing health condition.

Lipid-Based Nanotechnology: Liposome

Over the past several decades, liposomes have been extensively developed and used for various clinical applications such as in pharmaceutical, cosmetic, and dietetic fields, due to its versatility, biocompatibility, and biodegradability, as well as the ability to enhance the therapeutic index of free drugs. However, some challenges remain unsolved, including liposome premature leakage, manufacturing irreproducibility, and limited translation success. This article reviews various aspects of liposomes, including its advantages, major compositions, and common preparation techniques, and discusses present U.S. FDA-approved, clinical, and preclinical liposomal nanotherapeutics for treating and preventing a variety of human diseases. In addition, we summarize the significance of and challenges in liposome-enabled nanotherapeutic development and hope it provides the fundamental knowledge and concepts about liposomes and their applications and contributions in contemporary pharmaceutical advancement.

Potential of Nanotechnology-based Formulations in Combating Pulmonary Infectious Diseases: A Current Scenario

BACKGROUND

Pulmonary microbial infection is mainly caused by microbes like atypical bacteria, viruses, and fungi, on both the upper and lower respiratory tracts. One of the demands of the present is the use of nanotechnology-based treatments to fight various lung infections.

AIM

The main aim of the study is to explore all pulmonary infectious diseases and to compare the advanced and novel treatment approaches with the conventional methods which are available to treat infections.

METHODS

This work sheds light on pulmonary infectious diseases with their conventional and present treatment approaches along with a focus on the advantageous roles of nano-based formulations. In the literature, it has been reported that the respiratory system is the key target of various infectious diseases which gives rise to various challenges in the treatment of pulmonary infections.

RESULTS

The present review article describes the global situation of pulmonary infections and the different strategies which are available for their management, along with their limitations. The article also highlights the advantages and different examples of nanoformulations currently combating the limitations of conventional therapies.

CONCLUSION

The content of the present article further reflects on the summary of recently published research and review works on pulmonary infections, conventional methods of treatment with their limitations, and the role of nano-based approaches to combat the existing infectious diseases which will jointly help the researchers to produce effective drug formulations with desired pharmacological activities.

Brief on Recent Application of Liposomal Vaccines for Lower Respiratory Tract Viral Infections: From Influenza to COVID-19 Vaccines

Vaccination is the most effective means of preventing infectious diseases and saving lives. Modern biotechnology largely enabled vaccine development. In the meantime, recent advances in pharmaceutical technology have resulted in the emergence of nanoparticles that are extensively investigated as promising miniaturized drug delivery systems. Scientists are particularly interested in liposomes as an important carrier for vaccine development. Wide acceptability of liposomes lies in their flexibility and versatility. Due to their unique vesicular structure with alternating aqueous and lipid compartments, liposomes can enclose both hydrophilic and lipophilic compounds, including antigens. Liposome composition can be tailored to obtain the desired immune response and adjuvant characteristics. During the current pandemic of COVID-19, many liposome-based vaccines have been developed with great success. This review covers a liposome-based vaccine designed particularly to combat viral infection of the lower respiratory tract (LRT), i.e., infection of the lung, specifically in the lower airways. Viruses such as influenza, respiratory syncytial virus (RSV), severe acute respiratory syndrome (SARS-CoV-1 and SARS-CoV-2) are common causes of LRT infections, hence this review mainly focuses on this category of viruses.

Revolutionizing polymer-based nanoparticle-linked vaccines for targeting respiratory viruses: A perspective

Viral respiratory tract infections have significantly impacted global health as well as socio-economic growth. Respiratory viruses such as the influenza virus, respiratory syncytial virus (RSV), and the recent SARS-CoV-2 infection (COVID-19) typically infect the upper respiratory tract by entry through the respiratory mucosa before reaching the lower respiratory tract, resulting in respiratory disease. Generally, vaccination is the primary method in preventing virus pathogenicity and it has been shown to remarkably reduce the burden of various infectious diseases. Nevertheless, the efficacy of conventional vaccines may be hindered by certain limitations, prompting the need to develop novel vaccine delivery vehicles to immunize against various strains of respiratory viruses and to mitigate the risk of a pandemic. In this review, we provide an insight into how polymer-based nanoparticles can be integrated with the development of vaccines to effectively enhance immune responses for combating viral respiratory tract infections.

Application of nanotechnology in drug delivery systems for respiratory diseases (Review)

Respiratory disease is a common disease with a high incidence worldwide, which is a serious threat to human health, and is considered a societal and economic burden. The application of nanotechnology in drug delivery systems has created new treatments for respiratory diseases. Within this context, the present review systematically introduced the physicochemical properties of nanoparticles (NPs); reviewed the current research status of different nanocarriers in the treatment of respiratory diseases, including liposomes, solid lipid nanocarriers, polymeric nanocarriers, dendrimers, inorganic nanocarriers and protein nanocarriers; and discussed the main advantages and limitations of therapeutic nanomedicine in this field. The application of nanotechnology overcomes drug inherent deficiencies to a certain extent, and provides unlimited potential for the development of drugs to treat respiratory diseases. However, most of the related research work is in the preclinical experimental stage and safety assessment is still a challenging task. Future studies are needed to focus on the performance modification, molecular mechanism and potential toxicity of therapeutic nanomedicine.

Chitosan-adjuvanted Salmonella subunit nanoparticle vaccine for poultry delivered through drinking water and feed

Poor induction of mucosal immunity in the intestines by current Salmonella vaccines is a challenge to the poultry industry. We prepared and tested an oral deliverable Salmonella subunit vaccine containing immunogenic outer membrane proteins (OMPs) and flagellin (F) protein loaded and F-protein surface coated chitosan nanoparticles (CS NPs) (OMPs-F-CS NPs). The OMPs-F-CS NPs had mean particle size distribution of 514 nm, high positive charge and spherical in shape. In vitro and in vivo studies revealed the F-protein surface coated CS NPs were specifically targeted to chicken immune cells. The OMPs-F-CS NPs treatment of chicken immune cells upregulated TLRs, and Th1 and Th2 cytokines mRNA expression. Oral delivery of OMPs-F-CS NPs in birds enhanced the specific systemic IgY and mucosal IgA antibodies responses as well as reduced the challenge Salmonella load in the intestines. Thus, user friendly oral deliverable chitosan-based Salmonella vaccine for poultry is a viable alternative to current vaccines.

Nanoparticle-based vaccine development and evaluation against viral infections in pigs

Virus infections possess persistent health challenges in swine industry leading to severe economic losses worldwide. The economic burden caused by virus infections such as Porcine Reproductive and Respiratory Syndrome Virus, Swine influenza virus, Porcine Epidemic Diarrhea Virus, Porcine Circovirus 2, Foot and Mouth Disease Virus and many others are associated with severe morbidity, mortality, loss of production, trade restrictions and investments in control and prevention practices. Pigs can also have a role in zoonotic transmission of some viral infections to humans. Inactivated and modified-live virus vaccines are available against porcine viral infections with variable efficacy under field conditions. Thus, improvements over existing vaccines are necessary to: (1) Increase the breadth of protection against evolving viral strains and subtypes; (2) Control of emerging and re-emerging viruses; (3) Eradicate viruses localized in different geographic areas; and (4) Differentiate infected from vaccinated animals to improve disease control programs. Nanoparticles (NPs) generated from virus-like particles, biodegradable and biocompatible polymers and liposomes offer many advantages as vaccine delivery platform due to their unique physicochemical properties. NPs help in efficient antigen internalization and processing by antigen presenting cells and activate them to elicit innate and adaptive immunity. Some of the NPs-based vaccines could be delivered through both parenteral and mucosal routes to trigger efficient mucosal and systemic immune responses and could be used to target specific immune cells such as mucosal microfold (M) cells and dendritic cells (DCs). In conclusion, NPs-based vaccines can serve as novel candidate vaccines against several porcine viral infections with the potential to enhance the broader protective efficacy under field conditions. This review highlights the recent developments in NPs-based vaccines against porcine viral pathogens and how the NPs-based vaccine delivery system induces innate and adaptive immune responses resulting in varied level of protective efficacy.

The immune-adjuvant activity and the mechanism of resveratrol on pseudorabies virus vaccine in a mouse model

Resveratrol had shown various properties before, like immunomodulatory, anti-inflammatory and antiviral activities. Based on these properties, the present study was designed to evaluate the effects and mechanism of resveratrol as an immune-adjuvant for pseudorabies virus (PRV) vaccine. We found that oral administration of resveratrol to mice significantly increased the number of T lymphocytes in the spleen, and elevated the concentrations of antibodies and cytokines in the serum. Resveratrol (30 mg/kg) could enhance phagocytic capacity of peritoneal macrophage (PM) by boosting the percentage of phagocytosis, phagocytic index and the level of lysozyme. Resveratrol also enhanced antigen presentation function of PM by upregulating the expressions of CD86 and MHC-II. Further study revealed that resveratrol could increase the protein levels of TLR4, Ikk, IκBα, NF-κB and JNK when compared with non-adjuvant group. These results provide further insight into the mechanism of action in adjuvant activity of resveratrol, and also offer preclinical evidence for development as a PRV vaccine adjuvant.

Utility of the Neonatal Calf Model for Testing Vaccines and Intervention Strategies for Use against Human RSV Infection

Respiratory syncytial virus (RSV) is a significant cause of pediatric respiratory tract infections. It is estimated that two-thirds of infants are infected with RSV during the first year of life and it is one of the leading causes of death in this age group worldwide. Similarly, bovine RSV is a primary viral pathogen in cases of pneumonia in young calves and plays a significant role in bovine respiratory disease complex. Importantly, naturally occurring infection of calves with bovine RSV shares many features in common with human RSV infection. Herein, we update our current understanding of RSV infection in cattle, with particular focus on similarities between the calf and human infection, and the recent reports in which the neonatal calf has been employed for the development and testing of vaccines and therapeutics which may be applied to hRSV infection in humans.

The porcine tonsils and Peyer's patches: A stereological morphometric analysis in conventionally and artificially reared piglets

Selection for prolificacy in modern pig farming has resulted in increasing litter sizes. Since rearing large litters is challenging, artificial rearing of piglets with a milk replacer is an alternative strategy. It is hypothesized that the development of the piglets' mucosa-associated lymphoid tissues (MALT) is affected by these artificial conditions. Therefore, the stereologically estimated volumes of the tonsil of the soft palate, and the lingual, nasopharyngeal and paraepiglottic tonsils, as well as the jejunal and ileal Peyer's patches were statistically compared at day 21 postpartum between six conventionally reared piglets and six piglets that were artificially reared from day 7 onwards. In addition, six 7-day-old sow-fed piglets were examined to evaluate the effect of age. All tonsils and Peyer's patches significantly increased in volume with age. The rearing strategy had no significant effect on the volumes of the tonsil of the soft palate and the lingual tonsil. The former tonsil was by far the largest with a mean volume of 967.2 ± 122.4 mm³ and 822.3 ± 125.4 mm³ in the conventionally and artificially reared piglets, respectively. The lingual tonsil only measured 9.4 ± 6.4 mm³ and 6.3 ± 2.6 mm³ in conventionally and artificially reared groups, respectively. In contrast, the rearing strategy did affect the volumes of the nasopharyngeal and paraepiglottic tonsils, which had a mean volume of 137.1 ± 32.4 mm³ and 84.4 ± 26.9 mm³, and 30.7 ± 7.8 mm³ and 20.0 ± 3.9 mm³ in conventionally and artificially reared piglets, respectively. The rearing strategy did not affect the development of the Peyer's patches. At day 21, the jejunal Peyer's patches of the conventionally and artificially reared piglets presented a volume of 1.6 ± 0.4 cm³ and 1.3 ± 0.2 cm³, respectively. The volumes of the ileal Peyer's patch amounted to 15.1 ± 3.0 cm³ in conventionally reared piglets and 12.0 ± 2.6 cm³ in artificially reared piglets at day 21. The results showed that artificial rearing hampers the morphological development of the tonsils that are exposed to inhaled antigens, but the voluminous lymphoid tissues that sample oral antigens are not influenced. Since it is unlikely that the observed differences in both tonsils are due to the milk replacer, artificial rearing could be a valuable alternative for raising large litters. In addition, the presence of developing MALT in piglets allows for investigating the value of nasal and oral vaccination in this species for human or veterinary purposes.

Histological studies on the development of porcine tonsils after birth

Tonsils form the topographically first immune barrier of an organism against the invasion of pathogens. We used histology to study the development of tonsils of pigs after birth. At birth, the tonsils consist of diffuse lymphoid tissue without any lymphoid follicle aggregations. At the age of 7 days, lymphoid follicles appeared in the soft palate tonsil. The lymphoid layer of the nasopharyngeal tonsil, soft palate tonsil, and lingual tonsil became thicker, and lymphoid follicles in the lamina propria were clearly visible at the age of 21 days. Secondary lymphoid follicles were present in the nasopharyngeal tonsil at the age of 50 days, and in the soft palate tonsil at the age of 120 days. Dendritic cells (DCs), CD3⁺ T cells and IgA⁺ B cells in the soft palate tonsil, nasopharyngeal tonsil and lingual tonsil increased continuously, especially during the first 21 days. The results suggested that tonsils have an important role in local immune defense against invading antigens after birth and will be beneficial for understanding the mechanisms of immunity in these animals after nasal and oral vaccination.

A review of metabolomics approaches and their application in identifying causal pathways of childhood asthma

Because asthma is a disease that results from host-environment interactions, an approach that allows assessment of the effect of the environment on the host is needed to understand the disease. Metabolomics has appealing potential as an application to study pathways to childhood asthma development. The objective of this review is to provide an overview of metabolomics methods and their application to understanding host-environment pathways in asthma development. We reviewed recent literature on advances in metabolomics and their application to study pathways to childhood asthma development. We highlight the (1) potential of metabolomics in understanding the pathogenesis of disease and the discovery of biomarkers; (2) choice of metabolomics techniques, biospecimen handling, and data analysis; (3) application to studying the role of the environment on asthma development; (4) review of metabolomics applied to the outcome of asthma; (5) recommendations for application of metabolomics-based -omics data integration in understanding disease pathogenesis; and (6) limitations. In conclusion, metabolomics allows use of biospecimens to identify useful biomarkers and pathways involved in disease development and subsequently to inform a greater understanding of disease pathogenesis and endotypes and prediction of the clinical course of childhood asthma phenotypes.

Room Temperature Stable PspA-Based Nanovaccine Induces Protective Immunity

Streptococcus pneumoniae is a major causative agent of pneumonia, a debilitating disease particularly in young and elderly populations, and is the leading worldwide cause of death in children under the age of five. While there are existing vaccines against S. pneumoniae, none are protective across all serotypes. Pneumococcal surface protein A (PspA), a key virulence factor of S. pneumoniae, is an antigen that may be incorporated into future vaccines to address the immunological challenges presented by the diversity of capsular antigens. PspA has been shown to be immunogenic and capable of initiating a humoral immune response that is reactive across approximately 94% of pneumococcal strains. Biodegradable polyanhydrides have been studied as a nanoparticle-based vaccine (i.e., nanovaccine) platform to stabilize labile proteins, to provide adjuvanticity, and enhance patient compliance by providing protective immunity in a single dose. In this study, we designed a room temperature stable PspA-based polyanhydride nanovaccine that eliminated the need for a free protein component (i.e., 100% encapsulated within the nanoparticles). Mice were immunized once with the lead nanovaccine and upon challenge, presented significantly higher survival rates than animals immunized with soluble protein alone, even with a 25-fold reduction in protein dose. This lead nanovaccine formulation performed similarly to protein adjuvanted with Alum, however, with much less tissue reactogenicity at the site of immunization. By eliminating the free PspA from the nanovaccine formulation, the lead nanovaccine was efficacious after being stored dry for 60 days at room temperature, breaking the need for maintaining the cold chain. Altogether, this study demonstrated that a single dose PspA-based nanovaccine against S. pneumoniae induced protective immunity and provided thermal stability when stored at room temperature for at least 60 days.

Histological and anatomical structure of the nasal cavity of Bama minipigs

Objective

The nasal mucosa is equipped with abundant lymphatic tissues, serving as the first line of defense against invasion by microorganisms. In this study, we characterized the features of the nasal mucosa of Bama minipigs (Sus scrofa domestica) via histological analysis.

Methods

Five cross sections (I, II, III, IV, and V) were obtained from the distal end of the nasal cavity toward the pharynx (along the cavity axis) and examined. Specifically, CD3⁺ T cells, immunoglobulin A (IgA)⁺ cells, and M cells were detected by immunohistochemistry, while dendritic cells (DCs) were detected by immunofluorescence. The distribution of goblet cells was determined by periodic acid-Schiff (PAS) staining.

Results

The nasal cavity of Bama minipigs can be divided into three parts: the regio vestibularis (I, II), regio respiratoria (III, IV), and regio olfactoria (V). Lymphoid tissue was present at random locations in the nasal cavity. Abundant lymphoid tissue was located in the roof of the nasopharyngeal meatus and was continuous with the lymphoid tissue of the pharynx. The distribution of CD3⁺ T cells, IgA⁺ cells, M cells, and DCs increased distally in the nasal cavity.

Conclusions

The present work comprises a histological study of the nasal cavity of Bama minipigs, and will be beneficial for understanding the mechanisms of immunity in these animals after nasal vaccination.

Biodegradable nanoparticle delivery of inactivated swine influenza virus vaccine provides heterologous cell-mediated immune response in pigs

Swine influenza virus (SwIV) is one of the important zoonotic pathogens. Current flu vaccines have failed to provide cross-protection against evolving viruses in the field. Poly(lactic-co-glycolic acid) (PLGA) is a biodegradable FDA approved polymer and widely used in drug and vaccine delivery. In this study, inactivated SwIV H1N2 antigens (KAg) encapsulated in PLGA nanoparticles (PLGA-KAg) were prepared, which were spherical in shape with 200 to 300nm diameter, and induced maturation of antigen presenting cells in vitro. Pigs vaccinated twice with PLGA-KAg via intranasal route showed increased antigen specific lymphocyte proliferation and enhanced the frequency of T-helper/memory and cytotoxic T cells (CTLs) in peripheral blood mononuclear cells (PBMCs). In PLGA-KAg vaccinated and heterologous SwIV H1N1 challenged pigs, clinical flu symptoms were absent, while the control pigs had fever for four days. Grossly and microscopically, reduced lung pathology and viral antigenic mass in the lung sections with clearance of infectious challenge virus in most of the PLGA-KAg vaccinated pig lung airways were observed. Immunologically, PLGA-KAg vaccine irrespective of not significantly boosting the mucosal antibody response, it augmented the frequency of IFN-γ secreting total T cells, T-helper and CTLs against both H1N2 and H1N1 SwIV. In summary, inactivated influenza virus delivered through PLGA-NPs reduced the clinical disease and induced cross-protective cell-mediated immune response in a pig model. Our data confirmed the utility of a pig model for intranasal particulate flu vaccine delivery platform to control flu in humans.

Mucosal vaccine delivery: Current state and a pediatric perspective

Most childhood infections occur via the mucosal surfaces, however, parenterally delivered vaccines are unable to induce protective immunity at these surfaces. In contrast, delivery of vaccines via the mucosal routes can allow antigens to interact with the mucosa-associated lymphoid tissue (MALT) to induce both mucosal and systemic immunity. The induced mucosal immunity can neutralize the pathogen on the mucosal surface before it can cause infection. In addition to reinforcing the defense at mucosal surfaces, mucosal vaccination is also expected to be needle-free, which can eliminate pain and the fear of vaccination. Thus, mucosal vaccination is highly appealing, especially for the pediatric population. However, vaccine delivery across mucosal surfaces is challenging because of the different barriers that naturally exist at the various mucosal surfaces to keep the pathogens out. There have been significant developments in delivery systems for mucosal vaccination. In this review we provide an introduction to the MALT, highlight barriers to vaccine delivery at different mucosal surfaces, discuss different approaches that have been investigated for vaccine delivery across mucosal surfaces, and conclude with an assessment of perspectives for mucosal vaccination in the context of the pediatric population.