Chitosan alters inactivated respiratory syncytial virus vaccine elicited immune responses without affecting lung histopathology in mice

A novel N95 respirator with chitosan nanoparticles: mechanical, antiviral, microbiological and cytotoxicity evaluations

BACKGROUND

It is known that some sectors of hospitals have high bacteria and virus loads that can remain as aerosols in the air and represent a significant health threat for patients and mainly professionals that work in the place daily. Therefore, the need for a respirator able to improve the filtration barrier of N95 masks and even inactivating airborne virus and bacteria becomes apparent. Such a fact motivated the creation of a new N95 respirator which employs chitosan nanoparticles on its intermediate layer (SN95 + CNP).

RESULTS

The average chitosan nanoparticle size obtained was 165.20 ± 35.00 nm, with a polydispersity index of 0.36 ± 0.03 and a zeta potential of 47.50 ± 1.70 mV. Mechanical tests demonstrate that the SN95 + CNP respirator is more resistant and meets the safety requisites of aerosol penetration, resistance to breath and flammability, presenting higher potential to filtrate microbial and viral particles when compared to conventional SN95 respirators. Furthermore, biological in vitro tests on bacteria, fungi and mammalian cell lines (HaCat, Vero E6 and CCL-81) corroborate the hypothesis that our SN95 + CNP respirator presents strong antimicrobial activity and is safe for human use. There was a reduction of 96.83% of the alphacoronavirus virus and 99% of H1N1 virus and MHV-3 betacoronavirus after 120 min of contact compared to the conventional respirator (SN95), demonstrating that SN95 + CNP have a relevant potential as personal protection equipment.

CONCLUSIONS

Due to chitosan nanotechnology, our novel N95 respirator presents improved mechanical, antimicrobial and antiviral characteristics.

Polysaccharide-based nanoassemblies: From synthesis methodologies and industrial applications to future prospects

Polysaccharides, due to their remarkable features, have gained significant prominence in the sustainable production of nanoparticles (NPs). High market demand and minimal production cost, compared to the chemically synthesised NPs, demonstrate a drive towards polysaccharide-based nanoparticles (PSNPs) benign to environment. Various approaches are used for the synthesis of PSNPs including cross-linking, polyelectrolyte complexation, and self-assembly. PSNPs have the potential to replace a wide diversity of chemical-based agents within the food, health, medical and pharmacy sectors. Nevertheless, the considerable challenges associated with optimising the characteristics of PSNPs to meet specific targeting applications are of utmost importance. This review provides a detailed compilation of recent accomplishments in the synthesis of PSNPs, the fundamental principles and critical factors that govern their rational fabrication, as well as various characterisation techniques. Noteworthy, the multiple use of PSNPs in different disciplines such as biomedical, cosmetics agrochemicals, energy storage, water detoxification, and food-related realms, is accounted in detail. Insights into the toxicological impacts of the PSNPs and their possible risks to human health are addressed, and efforts made in terms of PSNPs development and optimising strategies that allow for enhanced delivery are highlighted. Finally, limitations, potential drawbacks, market diffusion, economic viability and future possibilities for PSNPs to achieve widespread commercial use are also discussed.

A multifunctional chitosan-based hydrogel with self-healing, antibacterial, and immunomodulatory effects as wound dressing

Bacterial infection often leads to inflammatory responses and delays wound healing. Chitosan (CS)-based composite hydrogels can hold desirable mechanical properties and maintain excellent antibacterial abilities, and thus may be promising as wound dressings. Although CS-based hydrogels have been widely studied on the antibacterial and wound-healing abilities, their immunomodulatory abilities were rarely evaluated. Herein, we developed a multifunctional CS/Poly[2-(methacryloyloxy)ethyl] trimethyl ammonium chloride (PMETAC) hydrogel. In vitro, this hydrogel exhibited self-healing ability and excellent biocompatibility, promoted macrophage polarization towards M2 phenotype, and showed desirable antibacterial activity. In vivo, this hydrogel accelerated the wound regeneration process by reducing bacterial burden, increasing collagen deposition, stimulating angiogenesis, promoting macrophage polarization to M2 direction, and shifting the balance of T helper type 17 (Th17) cells towards anti-inflammatory regulatory T (Treg) cells. This work revealed the potential immunomodulatory effect of CS-based wound dressings and thus may provide a novel target for developing efficient wound healing tools.

Antiviral and Antibacterial Sulfated Polysaccharide-Chitosan Nanocomposite Particles as a Drug Carrier

Drug delivery system (DDS) refers to the method of delivering drugs to the targeted sites with minimal risk. One popular strategy of DDS is using nanoparticles as a drug carrier, which are made from biocompatible and degradable polymers. Here, nanoparticles composed of Arthrospira-derived sulfated polysaccharide (AP) and chitosan were developed and expected to possess the capabilities of antiviral, antibacterial, and pH-sensitive properties. The composite nanoparticles, abbreviated as APC, were optimized for stability of morphology and size (~160 nm) in the physiological environment (pH = 7.4). Potent antibacterial (over 2 μg/mL) and antiviral (over 6.596 μg/mL) properties were verified in vitro. The pH-sensitive release behavior and release kinetics of drug-loaded APC nanoparticles were examined for various categories of drugs, including hydrophilic, hydrophobic, and protein drugs, under different pH values of the surroundings. Effects of APC nanoparticles were also evaluated in lung cancer cells and neural stem cells. The use of APC nanoparticles as a drug delivery system maintained the bioactivity of the drug to inhibit the proliferation of lung cancer cells (with ~40% reduction) and to relieve the growth inhibitory effect on neural stem cells. These findings indicate that the pH-sensitive and biocompatible composite nanoparticles of sulfated polysaccharide and chitosan well keep the antiviral and antibacterial properties and may serve as a promising multifunctional drug carrier for further biomedical applications.

Protective immunity against spring viremia of carp virus by mannose modified chitosan loaded DNA vaccine

Spring viremia of carp virus (SVCV) usually be considered as one of the serious in viral diseases of aquaculture, and DNA vaccine with novel delivery mechanism or adjuvant has proven to be a promising and effective strategy to control aquatic animal diseases. In this study, the mannose-modified chitosan, a carrier system for vaccine delivery, were used to developed a chitosan-encapsulated DNA vaccine (CS-M-G) against SVCV, then investigated immune response induced by the vaccine. Our results showed that CS-M-G was confirmed the spherical or elliptical with even distribution and ranging from approximately 50 to 150 nm in size, the expression of the antigen gene could still be detected after 21 d post vaccination. The CS-M-G induces the highest antibody levels in the 20 μg dose group which is about 3 times than naked plasmid group at 21 d post vaccination, and still hold a higher level than control group at 28 d post vaccination. On the side, strongest protection with relative percent survival of 62.1% in the 20 μg CS-M-G group, which could produce significantly higher enzyme activities and up-regulated expression of immune-associated genes than control group. Thus, our results indicate that DNA vaccine loaded with mannose-modified chitosan induces strong immune response and provided an effective protection against SVCV infection, may be helpful and extended for developing more aquatic animal vaccines in the future.

Research progress on the antiviral activities of natural products and their derivatives: Structure–activity relationships

Viruses spread rapidly and are well-adapted to changing environmental events. They can infect the human body readily and trigger fatal diseases. A limited number of drugs are available for specific viral diseases, which can lead to non-efficacy against viral variants and drug resistance, so drugs with broad-spectrum antiviral activity are lacking. In recent years, a steady stream of new viral diseases has emerged, which has prompted development of new antiviral drugs. Natural products could be employed to develop new antiviral drugs because of their innovative structures and broad antiviral activities. This review summarizes the progress of natural products in antiviral research and their bright performance in drug resistance issues over the past 2 decades. Moreover, it fully discusses the effect of different structural types of natural products on antiviral activity in terms of structure–activity relationships. This review could provide a foundation for the development of antiviral drugs.

Advances in the Prophylaxis of Respiratory Infections by the Nasal and the Oromucosal Route: Relevance to the Fight with the SARS-CoV-2 Pandemic

In this time of COVID-19 pandemic, the strategies for prevention of the infection are a primary concern. Looking more globally on the subject and acknowledging the high degree of misuse of protective face masks from the population, we focused this review on alternative pharmaceutical developments eligible for self-defense against respiratory infections. In particular, the attention herein is directed to the nasal and oromucosal formulations intended to boost the local immunity, neutralize or mechanically “trap” the pathogens at the site of entry (nose or mouth). The current work presents a critical review of the contemporary methods of immune- and chemoprophylaxis and their suitability and applicability in topical mucosal dosage forms for SARS-CoV-2 prophylaxis.

Pulmonary delivery of mucosal nanovaccines

Mucosal vaccination can elicit both systemic and mucosal immunity, and therefore has the potential to not only treat mucosal immune diseases, prevent the pathogen infection at the mucosal entry sites, but also treat distant or systemic immune disorders. However, only a few mucosal vaccines have been approved for human use in the clinic. Effective mucosal immunization requires the delivery of immunogenic agents to appropriate mucosal surfaces, which remains significantly challenging due to the essential biological barriers presenting at mucosal tissues. In the past decade, remarkable progress has been made in the development of pulmonary mucosal nanovaccines. The nanovaccines leverage advanced nanoparticle-based pulmonary delivery technologies on the characteristics of large surface area and rich antigen presentation cell environment of the lungs for triggering robust immune protection against various mucosal diseases. Herein, we review current methods and formulations of pulmonary delivery, discuss the design strategies of mucosal nanovaccines for potent and long-lasting immune responses, and highlight recent advances in the application of lipid-based pulmonary nanovaccines against mucosal diseases. These advances promise to accelerate the development of novel mucosal nanovaccines for the prophylaxis and therapy of infectious diseases, and cancer, as well as autoimmune disorders at mucosal tissues.

Recent advances in antiviral activities and potential mechanisms of sulfated polysaccharides

Natural polysaccharides derived from plants, fungi and animals are well known as ideal functional products with multiple biological activities and few side effects. Among them, natural occurring sulfated polysaccharides and those from synthetic origin are increasingly causing more attention worldwide, as they have been proved to possess broad-spectrum antiviral activities. The focus of this review is on analyzing the current state of knowledge about the origin of sulfated polysaccharides, more importantly, the potential connection between the structure and their antiviral mechanisms. Sulfated polysaccharide may interfere with a few steps in the virus life cycle (i.e. adsorption, invasion, transcription and replication) and/or improve the host antiviral immune response. Moreover, their antiviral activity was affected by degree of substitution, substitution position, molecular weight, and spatial conformation. This review may provide approach for the development of novel and potent therapeutic agents.

Marine sulfated polysaccharides as potential antiviral drug candidates to treat Corona Virus disease (COVID-19)

The viral infection caused by SARS-CoV-2 has increased the mortality rate and engaged several adverse effects on the affected individuals. Currently available antiviral drugs have found to be unsuccessful in the treatment of COVID-19 patients. The demand for efficient antiviral drugs has created a huge burden on physicians and health workers. Plasma therapy seems to be less accomplishable due to insufficient donors to donate plasma and low recovery rate from viral infection. Repurposing of antivirals has been evolved as a suitable strategy in the current treatment and preventive measures. The concept of drug repurposing represents new experimental approaches for effective therapeutic benefits. Besides, SARS-CoV-2 exhibits several complications such as lung damage, blood clot formation, respiratory illness and organ failures in most of the patients. Based on the accumulation of data, sulfated marine polysaccharides have exerted successful inhibition of virus entry, attachment and replication with known or unknown possible mechanisms against deadly animal and human viruses so far. Since the virus entry into the host cells is the key process, the prevention of such entry mechanism makes any antiviral strategy effective. Enveloped viruses are more sensitive to polyanions than non-enveloped viruses. Besides, the viral infection caused by RNA virus types embarks severe oxidative stress in the human body that leads to malfunction of tissues and organs. In this context, polysaccharides play a very significant role in providing shielding effect against the virus due to their polyanionic rich features and a molecular weight that hinders their reactive surface glycoproteins. Significantly the functional groups especially sulfate, sulfate pattern and addition, uronic acids, monosaccharides, glycosidic linkage and high molecular weight have greater influence in the antiviral activity. Moreover, they are very good antioxidants that can reduce the free radical generation and provokes intracellular antioxidant enzymes. Additionally, polysaccharides enable a host-virus immune response, activate phagocytosis and stimulate interferon systems. Therefore, polysaccharides can be used as candidate drugs, adjuvants in vaccines or combination with other antivirals, antioxidants and immune-activating nutritional supplements and antiviral materials in healthcare products to prevent SARS-CoV-2 infection.

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.

Role of chitosan based nanomedicines in the treatment of chronic respiratory diseases

Chitosan-loaded nanomedicines provide a greater opportunity for the treatment of respiratory diseases. Natural biopolymer chitosan and its derivatives have a large number of proven pharmacological actions like antioxidant, wound healing, immuno-stimulant, hypocholesterolemic, antimicrobial, obesity treatment, anti-inflammatory, anticancer, bone tissue engineering, antifungal, regenerative medicine, anti-diabetic and mucosal adjuvant, etc. which attracted its use in the pharmaceutical industry. As compared to other polysaccharides, chitosan has excellent mucoadhesive characteristics, less viscous, easily modified into the chemical and biological molecule and gel-forming property due to which the drugs retain in the respiratory tract for a longer period of time providing enhanced therapeutic action of the drug. Chitosan-based nanomedicines would have the greatest effect when used to transport poor water soluble drugs, macromolecules like proteins, and peptides through the lungs. In this review, we highlight and discuss the role of chitosan and its nanomedicines in the treatment of chronic respiratory diseases such as pneumonia, asthma, COPD, lung cancer, tuberculosis, and COVID-19.

Application prospect of polysaccharides in the development of anti-novel coronavirus drugs and vaccines

Since the outbreak of the novel coronavirus disease COVID-19, caused by the SARS-CoV-2 virus, it has spread rapidly worldwide and poses a great threat to public health. This is the third serious coronavirus outbreak in <20 years, following SARS in 2002-2003 and MERS in 2012. So far, there are almost no specific clinically effective drugs and vaccines available for COVID-19. Polysaccharides with good safety, immune regulation and antiviral activity have broad application prospects in anti-virus, especially in anti-coronavirus applications. Here, we reviewed the antiviral mechanisms of some polysaccharides, such as glycosaminoglycans, marine polysaccharides, traditional Chinese medicine polysaccharides, and their application progress in anti-coronavirus. In particular, the application prospects of polysaccharide-based vaccine adjuvants, nanomaterials and drug delivery systems in the fight against novel coronavirus were also analyzed and summarized. Additionally, we speculate the possible mechanisms of polysaccharides anti-SARS-CoV-2, and propose the strategy of loading S or N protein from coronavirus onto polysaccharide capped gold nanoparticles vaccine for COVID-19 treatment. This review may provide a new approach for the development of COVID-19 therapeutic agents and vaccines.

Respiratory Syncytial Virus F Subunit Vaccine With AS02 Adjuvant Elicits Balanced, Robust Humoral and Cellular Immunity in BALB/c Mice

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory illness, particularly in infants, the elderly, and immunocompromised adults. There is no licensed commercial vaccine against RSV. Importantly, formalin-inactivated RSV vaccines mediate enhanced respiratory disease. RSV fusion (F) protein with pre-fusion conformation is a promising candidate subunit vaccine. However, some problems remain to be solved, such as low immunogenicity and humoral immunity bias. Adjuvants can effectively enhance and adjust vaccine immune responses. In this study, we formulated pre-fusion RSV-F protein with the adjuvants, Alhydrogel, MF59, AS03, AS02, and glycol chitosan (GCS). We then conducted head-to-head comparisons of vaccine-induced immune responses in BALB/c mice. All adjuvanted vaccines enhanced antigen-specific and neutralizing antibody titers and viral clearance and gave an order of adjuvant activity: AS02 > AS03, MF59 > GCS, and Alhydrogel. Among them, AS02 elicited the highest antibody expression, which persisted until week 18. Moreover, AS02 significantly enhanced Th1 type immune response in immunized mice. Mice in the AS02 group also showed faster recovery from viral attacks in challenge tests. Further transcriptome analysis revealed that AS02 regulates immune balance by activating TLR-4 and promotes Th1-type immune responses. These results suggest that AS02 may be an excellent candidate adjuvant for RSV-F subunit vaccines. This study also provides valuable information regarding the effect of other adjuvants on immune responses of RSV-F subunit vaccines.

Immunomodulation as a Novel Strategy for Prevention and Treatment of Bordetella spp. Infections

Well-adapted pathogens have evolved to survive the many challenges of a robust immune response. Defending against all host antimicrobials simultaneously would be exceedingly difficult, if not impossible, so many co-evolved organisms utilize immunomodulatory tools to subvert, distract, and/or evade the host immune response. Bordetella spp. present many examples of the diversity of immunomodulators and an exceptional experimental system in which to study them. Recent advances in this experimental system suggest strategies for interventions that tweak immunity to disrupt bacterial immunomodulation, engaging more effective host immunity to better prevent and treat infections. Here we review advances in the understanding of respiratory pathogens, with special focus on Bordetella spp., and prospects for the use of immune-stimulatory interventions in the prevention and treatment of infection.