Spectrum and mechanisms of inflammasome activation by chitosan

Nucleic acid vaccines: innovations, efficacy, and applications in at-risk populations

For more than two centuries, the field of vaccine development has progressed through the adaptation of novel platforms in parallel with technological developments. Building off the advantages and shortcomings of first and second-generation vaccine platforms, the advent of third-generation nucleic acid vaccines has enabled new approaches to tackle emerging infectious diseases, cancers, and pathogens where vaccines remain unavailable. Unlike traditional vaccine platforms, nucleic acid vaccines offer several new advantages, including their lower cost and rapid production, which was widely demonstrated during the COVID-19 pandemic. Beyond production, DNA and mRNA vaccines can elicit unique and targeted responses through specialized design and delivery approaches. Considering the growth of nucleic acid vaccine research over the past two decades, the evaluation of their efficacy in at-risk populations is paramount for refining and improving vaccine design. Importantly, the aging population represents a significant portion of individuals highly susceptible to infection and disease. This review seeks to outline the major impairments in vaccine-induced responses due to aging that may be targeted for improvement with design and delivery components encompassing mRNA and DNA vaccine formulations. Results of pre-clinical and clinical applications of these vaccines in aged animal models and humans will also be evaluated to outline current successes and limitations observed in these platforms.

Harnessing the immunomodulatory potential of chitosan and its derivatives for advanced biomedical applications

The success of biomaterial applications in medicine, particularly in tissue engineering, relies on achieving a balance between promoting tissue regeneration and controlling the immune response. Due to its natural origin, high biocompatibility, and versatility, chitosan has emerged as a promising biomaterial especially for immunomodulation purposes. Immunomodulation, refers to the deliberate alteration of the immune system's activity to achieve a desired therapeutic effect either by enhancing or suppressing the function of specific immune cells, signaling pathways, or cytokine production. This modulation opens up the unlimited possibilities for the use of biomaterials, especially about the use of natural polymers such as chitosan. Although numerous chitosan-based immunoregulatory strategies have been demonstrated over the past two decades, the lack of in-depth exploration hinders the full potential of strategies that include chitosan and its derivatives in biomedical applications. Thus, in this review, the possible immunomodulatory effects of chitosan, chitosan derivatives and their potential combined with various agents and therapies are investigated in detail. Moreover, this report includes agents for localized immune response control, chitosan-based strategies with complementary immunomodulatory properties to create synergistic effects that will influence the success of cell therapies for enhanced tissue acceptance and regeneration. Finally, the challenges and outlook of chitosan-based therapies as a powerful tool for improving immunomodulatory applications are discussed for paving the way for further studies.

Role of NLRP3 inflammasome in nanoparticle adjuvant-mediated immune response

The nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome is pivotal in orchestrating the immune response induced by nanoparticle adjuvants. Understanding the intricate mechanisms underlying the activation of NLRP3 inflammasome by these adjuvants is crucial for deciphering their immunomodulatory properties. This review explores the involvement of the NLRP3 inflammasome in mediating immune responses triggered by nanoparticle adjuvants. It delves into the signaling pathways and cellular mechanisms involved in NLRP3 activation, highlighting its significance in modulating the efficacy and safety of nanoparticle-based adjuvants. A comprehensive grasp of the interplay between NLRP3 inflammasome and nanoparticle adjuvants holds promise for optimizing vaccine design and advancing immunotherapeutic strategies.

A respiratory mucosal vaccine based on chitosan/aluminum adjuvant induces both mucosal and systemic immune responses

The respiratory mucosa serves as a critical barrier against the invasion of pathogens. Effective mucosal vaccines are essential for enhancing local immunity. However, there is an urgent need to develop new mucosal adjuvants. Chitosan is preferred as a mucosal adjuvant due to its mucosal adhesion and immunostimulatory properties. In this work, a novel mucosal adjuvant was synthesized by combining nano-aluminum hydroxide and chitosan (Al-CS), formulating a particle size approximately 1.5 μm. In vitro assays revealed that Al-CS notably promotes antigen uptake by enhancing activation and maturation of dendritic cells and macrophages. Furthermore, in vivo experiments indicated that Al-CS could extend antigen release duration, facilitate immune cell migration to the lungs, stimulates antigen-presenting cell maturation, enhances antigen presentation and significantly improves both humoral and cellular immunity as well as B/T cell memory differentiation. The immunological potential of Al-CS exceeds that of either aluminum or chitosan alone, making it a promising and safe adjuvant for the advancement of mucosal vaccine carrier systems.

The malic acid inhibiting inflammation in ankylosing spondylitis by interfering M1 macrophage polarization

Ankylosing spondylitis (AS) is a motor system immune disease with significant genetic characteristics, resulting in joint fusion, deformity, rigidity, seriously affecting the quality of life of patients. Inflammatory bowel disease (IBD), characterized by intestinal mucosal damage and inflammatory changes, the most common extra-articular manifestation of AS. Due to the limitations of the application of therapeutic drugs, it is urgent to look for new mechanisms and strategies to effectively inhibit AS inflammation is. The content of malic acid (MA) was significantly decreased in peripheral blood of AS patients, and it was significantly negatively correlated with C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). MA dramatically alleviated spinal damage and intestinal inflammation in mouse models of AS induced by β-1, 3-glucan solution. Mechanically, MA suppressed the NF-κB pathway by inhibiting polarization of M1-type macrophages, thereby alleviating spinal and intestinal inflammation. From the perspective of material metabolism, this study explored the mechanism by which MA, an intermediate product of glucose metabolism, reducing M1 polarization of macrophages to inhibit AS inflammation, providing a reliable basis for the pathogenesis research and precise targeted treatment of AS in the later stage.

Chitosan immunomodulation: insights into mechanisms of action on immune cells and signaling pathways

Chitosan, a biodegradable and biocompatible natural polymer composed of β-(1-4)-linked N-acetyl glucosamine (GlcNAc) and d-glucosamine (GlcN) and derived from crustacean shells, has been widely studied for various biomedical applications, including drug delivery, cartilage repair, wound healing, and tissue engineering, because of its unique physicochemical properties. One of the most promising areas of research is the investigation of the immunomodulatory properties of chitosan, since the biopolymer has been shown to modulate the maturation, activation, cytokine production, and polarization of dendritic cells and macrophages, two key immune cells involved in the initiation and regulation of innate and adaptive immune responses, leading to enhanced immune responses. Several signaling pathways, including the cGAS-STING, STAT-1, and NLRP3 inflammasomes, are involved in chitosan-induced immunomodulation. This review provides a comprehensive overview of the current understanding of the in vitro immunomodulatory effects of chitosan. This information may facilitate the development of chitosan-based therapies and vaccine adjuvants for various immune-related diseases.

Chitosan siRNA Nanoparticles Produce Significant Non-Toxic Functional Gene Silencing in Kidney Cortices

Chitosan shows effective nucleic acid delivery. To understand the influence of chitosan's molecular weight, dose, payload, and hyaluronic acid coating on in vivo toxicity, immune stimulation, biodistribution and efficacy, precisely characterized chitosans were formulated with unmodified or chemically modified siRNA to control for innate immune stimulation. The hemocompatibility, cytokine induction, hematological and serological responses were assessed. Body weight, clinical signs, in vivo biodistribution and functional target knockdown were monitored. Hemolysis was found to be dose- and MW-dependent with the HA coating abrogating hemolysis. Compared to cationic lipid nanoparticles, uncoated and HA-coated chitosan nanoparticles did not induce immune stimulation or hematologic toxicity. Liver and kidney biomarkers remained unchanged with chitosan formulations, while high doses of cationic lipid nanoparticles led to increased transaminase levels and a decrease in body weight. Uncoated and HA-coated nanoparticles accumulated in kidneys with functional knockdown for uncoated chitosan formulations reaching 60%, suggesting potential applications in the treatment of kidney diseases.

Bioarchitectural Design of Bioactive Biopolymers: Structure-Function Paradigm for Diabetic Wound Healing

Chronic wounds such as diabetic ulcers are a major complication in diabetes caused by hyperglycemia, prolonged inflammation, high oxidative stress, and bacterial bioburden. Bioactive biopolymers have been found to have a biological response in wound tissue microenvironments and are used for developing advanced tissue engineering strategies to enhance wound healing. These biopolymers possess innate bioactivity and are biodegradable, with favourable mechanical properties. However, their bioactivity is highly dependent on their structural properties, which need to be carefully considered while developing wound healing strategies. Biopolymers such as alginate, chitosan, hyaluronic acid, and collagen have previously been used in wound healing solutions but the modulation of structural/physico-chemical properties for differential bioactivity have not been the prime focus. Factors such as molecular weight, degree of polymerization, amino acid sequences, and hierarchical structures can have a spectrum of immunomodulatory, anti-bacterial, and anti-oxidant properties that could determine the fate of the wound. The current narrative review addresses the structure-function relationship in bioactive biopolymers for promoting healing in chronic wounds with emphasis on diabetic ulcers. This review highlights the need for characterization of the biopolymers under research while designing biomaterials to maximize the inherent bioactive potency for better tissue regeneration outcomes, especially in the context of diabetic ulcers.

Spray-dried pH-sensitive chitosan microparticles loaded with Mycobacterium bovis BCG intended for supporting treatment of Helicobacter pylori infection

Gram-negative spiral-shaped Helicobacter pylori (Hp) bacteria induce the development of different gastric disorders. The growing resistance of Hp to antibiotics prompts to search for new therapeutic formulations. A promising candidate is Mycobacterium bovis BCG (BCG) with immunomodulatory properties. Biodegradable mucoadhesive chitosan is a good carrier for delivering BCG mycobacteria to the gastric mucosal environment. This study aimed to show whether BCG bacilli are able to increase the phagocytic activity of Cavia porcellus-guinea pig macrophages derived from the bone marrow towards fluorescently labeled Escherichia coli. Furthermore, to encapsulate live BCG bacilli, in spray-dried chitosan microparticles (CHI-MPs), and assess the pH-dependent release of mycobacteria in pH conditions mimicking gastric (acidic) or gut (alkaline) milieu. Microparticles (MPs) were made of chitosan and coated with Pluronic F-127-(Plur) or N-Acetyl-D-Glucosamine-(GlcNAc) to increase the MPs resistance to low pH or to increase anti-Hp effect, respectively. Spray-drying method was used for microencapsulation of live BCG. The biosafety of tested CHI-MPs has been confirmed using cell models in vitro and the model of guinea pig in vivo. The CHI-MPs loaded with BCG released live mycobacteria at pH 3.0 (CHI-GlcNAc-MPs) or pH 8.0. (CHI-Plur-MPs). The CHI-MPs loaded with live BCG can be used for per os inoculation of Cavia porcellus to check the effectiveness of delivered mycobacteria in increasing anti-H. pylori host response.

Polysaccharide-based hydrogels for medical devices, implants and tissue engineering: A review

Hydrogels are highly biocompatible biomaterials composed of crosslinked three-dimensional networks of hydrophilic polymers. Owing to their natural origin, polysaccharide-based hydrogels (PBHs) possess low toxicity, high biocompatibility and demonstrate in vivo biodegradability, making them great candidates for use in various biomedical devices, implants, and tissue engineering. In addition, many polysaccharides also show additional biological activities such as antimicrobial, anticoagulant, antioxidant, immunomodulatory, hemostatic, and anti-inflammatory, which can provide additional therapeutic benefits. The porous nature of PBHs allows for the immobilization of antibodies, aptamers, enzymes and other molecules on their surface, or within their matrix, potentiating their use in biosensor devices. Specific polysaccharides can be used to produce transparent hydrogels, which have been used widely to fabricate ocular implants. The ability of PBHs to encapsulate drugs and other actives has been utilized for making neural implants and coatings for cardiovascular devices (stents, pacemakers and venous catheters) and urinary catheters. Their high water-absorption capacity has been exploited to make superabsorbent diapers and sanitary napkins. The barrier property and mechanical strength of PBHs has been used to develop gels and films as anti-adhesive formulations for the prevention of post-operative adhesion. Finally, by virtue of their ability to mimic various body tissues, they have been explored as scaffolds and bio-inks for tissue engineering of a wide variety of organs. These applications have been described in detail, in this review.

A detailed molecular network map and model of the NLRP3 inflammasome

The NLRP3 inflammasome is a key regulator of inflammation that responds to a broad range of stimuli. The exact mechanism of activation has not been determined, but there is a consensus on cellular potassium efflux as a major common denominator. Once NLRP3 is activated, it forms high-order complexes together with NEK7 that trigger aggregation of ASC into specks. Typically, there is only one speck per cell, consistent with the proposal that specks form - or end up at - the centrosome. ASC polymerisation in turn triggers caspase-1 activation, leading to maturation and release of IL-1β and pyroptosis, i.e., highly inflammatory cell death. Several gain-of-function mutations in the NLRP3 inflammasome have been suggested to induce spontaneous activation of NLRP3 and hence contribute to development and disease severity in numerous autoinflammatory and autoimmune diseases. Consequently, the NLRP3 inflammasome is of significant clinical interest, and recent attention has drastically improved our insight in the range of involved triggers and mechanisms of signal transduction. However, despite recent progress in knowledge, a clear and comprehensive overview of how these mechanisms interplay to shape the system level function is missing from the literature. Here, we provide such an overview as a resource to researchers working in or entering the field, as well as a computational model that allows for evaluating and explaining the function of the NLRP3 inflammasome system from the current molecular knowledge. We present a detailed reconstruction of the molecular network surrounding the NLRP3 inflammasome, which account for each specific reaction and the known regulatory constraints on each event as well as the mechanisms of drug action and impact of genetics when known. Furthermore, an executable model from this network reconstruction is generated with the aim to be used to explain NLRP3 activation from priming and activation to the maturation and release of IL-1β and IL-18. Finally, we test this detailed mechanistic model against data on the effect of different modes of inhibition of NLRP3 assembly. While the exact mechanisms of NLRP3 activation remains elusive, the literature indicates that the different stimuli converge on a single activation mechanism that is additionally controlled by distinct (positive or negative) priming and licensing events through covalent modifications of the NLRP3 molecule. Taken together, we present a compilation of the literature knowledge on the molecular mechanisms on NLRP3 activation, a detailed mechanistic model of NLRP3 activation, and explore the convergence of diverse NLRP3 activation stimuli into a single input mechanism.

The Distinct Properties of Polysaccharide Nanoparticles Tune Immune Responses against mRNA Antigen via Stimulator of Interferon Genes-Mediated Autophagy and Inflammasome

mRNA antigens require powerful nanocarriers for efficient delivery, as well as immunomodulators for controlling their excessive immunogenicity. While lipid nanoparticles (LNPs) used in mRNA vaccines exhibited systemic toxicity, there is an urgent need for developing potential nanoparticles with strong immunoenhancing effects for mRNA antigens. Although natural polysaccharides as adjuvants assisted various types of antigens in triggering potent immune responses, they have been rarely investigated in mRNA vaccines. Here, we constructed four polysaccharide nanoparticles with different molecular weights (MWs) to deliver and protect mRNA antigens, and boosted antigen cross-presentation, DC maturation, CD4+/CD8+T cell responses and humoral immune responses. Importantly, the immunoenhancing capacities of polysaccharide nanoparticles were highly dependent on their MW properties. CS NPs with high MW initiated stimulator of interferon genes (STING)-mediated autophagy and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome signaling, consequently possessing superior mRNA antigen-specific immune responses in vitro and in vivo. In contrast, CS NPs with low MWs induced NLRP3 signaling without STING or autophagy activation, which failed to induce robust immune responses. Therefore, it uncovered the MW-dependent immunoenhancing effects and mechanism of polysaccharide nanoparticles, providing a platform for designing potential nanosized polysaccharide immunomodulators for mRNA vaccines.

Unraveling the potential of 3D bioprinted immunomodulatory materials for regulating macrophage polarization: State-of-the-art in bone and associated tissue regeneration

Macrophage-assisted immunomodulation is an alternative strategy in tissue engineering, wherein the interplay between pro-inflammatory and anti-inflammatory macrophage cells and body cells determines the fate of healing or inflammation. Although several reports have demonstrated that tissue regeneration depends on spatial and temporal regulation of the biophysical or biochemical microenvironment of the biomaterial, the underlying molecular mechanism behind immunomodulation is still under consideration for developing immunomodulatory scaffolds. Currently, most fabricated immunomodulatory platforms reported in the literature show regenerative capabilities of a particular tissue, for example, endogenous tissue (e.g., bone, muscle, heart, kidney, and lungs) or exogenous tissue (e.g., skin and eye). In this review, we briefly introduced the necessity of the 3D immunomodulatory scaffolds and nanomaterials, focusing on material properties and their interaction with macrophages for general readers. This review also provides a comprehensive summary of macrophage origin and taxonomy, their diverse functions, and various signal transduction pathways during biomaterial-macrophage interaction, which is particularly helpful for material scientists and clinicians for developing next-generation immunomodulatory scaffolds. From a clinical standpoint, we briefly discussed the role of 3D biomaterial scaffolds and/or nanomaterial composites for macrophage-assisted tissue engineering with a special focus on bone and associated tissues. Finally, a summary with expert opinion is presented to address the challenges and future necessity of 3D bioprinted immunomodulatory materials for tissue engineering.

Polymeric nanoparticles for DNA vaccine-based cancer immunotherapy: a review

Cancer is one of the leading causes of death and mortality in the world. There is an essential need to develop new drugs or therapeutic approaches to manage treatment-resistant cancers. Cancer immunotherapy is a type of cancer treatment that uses the power of the body's immune system to prevent, control, and eliminate cancer. One of the materials used as a vaccine in immunotherapy is DNA. The application of polymeric nanoparticles as carriers for DNA vaccines could be an effective therapeutic approach to activate immune responses and increase antigen presentation efficiency. Various materials have been used as polymeric nanoparticles, including: chitosan, poly (lactic-co-glycolic acid), Polyethylenimine, dendrimers, polypeptides, and polyesters. Application of these polymer nanoparticles has several advantages, including increased vaccine delivery, enhanced antigen presentation, adjuvant effects, and more sustainable induction of the immune system. Besides many clinical trials and commercial products that were developed based on polymer nanoparticles, there is still a need for more comprehensive studies to increase the DNA vaccine efficiency in cancer immunotherapy using this type of carrier.

Enhancing effect of chitosan nanoparticles on the immune efficacy of Bordetella bronchiseptica outer membrane vesicles

The outer membrane vesicle (OMV) of bacteria is a bilayer membrane vesicle with a diameter of about 10-300 nm that is secreted during the growth of Gram-negative bacteria. OMV is considered as a high-quality vaccine candidate antigen because of its natural immunogenicity and non-replicability. Although the excellent antigenicity of OMV has been widely confirmed, its instability and heterogeneity greatly affect its immune effect. Many studies have demonstrated that in combination with nanoparticles can enhance the stability of OMV. In this study, OMVs were used to coat chitosan nanoparticles (CNPs) and obtain a stable OMV vaccine. The characteristics, including morphology, hydrodynamic size, and zeta potential were evaluated. The immune protection of CNP-OMV and anti-infection efficacy were examined and compared in vivo and in vitro. The results showed that the CNP-OMV were homogenous with a size of 139 nm and a stable core-shell structure. And CNP-OMV could significantly increase the cell proliferation, phagocytosis and TNF-α, IL-6 and IL-10 secretion of RAW264.7 in vitro. In vivo, CNP-OMV could significantly increase the levels of anti-Bb and OMV IgG antibodies. Levels of blood lymphocyte, and Th1 (IFN-γ, IL-12), Th2 (IL-4, IL-5), and Th17 (IL-17, TNF-α) type cytokines in the serum were all significantly increased. At the same time, CNP-OMV could significantly reduce the bacterial invading the lungs of challenged rabbits. And CNP-OMV could largely protect the lungs from injury. The above results showed that CNP-OMV had a good immune efficacy and could resist the infection of Bordetella bronchiseptica. This study provided a scientific basis for the development of novel effective and safe vaccine against Bordetella bronchiseptica, and also provided a new idea for the development of new bacterial vaccine.

Polyplex designs for improving the stability and safety of RNA therapeutics

Nanoparticle-based delivery systems have contributed to the recent clinical success of RNA therapeutics, including siRNA and mRNA. RNA delivery using polymers has several distinct properties, such as enabling RNA delivery into extra-hepatic organs, modulation of immune responses to RNA, and regulation of intracellular RNA release. However, delivery systems should overcome safety and stability issues to achieve widespread therapeutic applications. Safety concerns include direct damage to cellular components, innate and adaptive immune responses, complement activation, and interaction with surrounding molecules and cells in the blood circulation. The stability of the delivery systems should balance extracellular RNA protection and controlled intracellular RNA release, which requires optimization for each RNA species. Further, polymer designs for improving safety and stability often conflict with each other. This review covers advances in polymer-based approaches to address these issues over several years, focusing on biological understanding and design concepts for delivery systems rather than material chemistry.

Adjuvant physiochemistry and advanced nanotechnology for vaccine development

Vaccines comprising innovative adjuvants are rapidly reaching advanced translational stages, such as the authorized nanotechnology adjuvants in mRNA vaccines against COVID-19 worldwide, offering new strategies to effectively combat diseases threatening human health. Adjuvants are vital ingredients in vaccines, which can augment the degree, extensiveness, and longevity of antigen specific immune response. The advances in the modulation of physicochemical properties of nanoplatforms elevate the capability of adjuvants in initiating the innate immune system and adaptive immunity, offering immense potential for developing vaccines against hard-to-target infectious diseases and cancer. In this review, we provide an essential introduction of the basic principles of prophylactic and therapeutic vaccination, key roles of adjuvants in augmenting and shaping immunity to achieve desired outcomes and effectiveness, and the physiochemical properties and action mechanisms of clinically approved adjuvants for humans. We particularly focus on the preclinical and clinical progress of highly immunogenic emerging nanotechnology adjuvants formulated in vaccines for cancer treatment or infectious disease prevention. We deliberate on how the immune system can sense and respond to the physicochemical cues (e.g., chirality, deformability, solubility, topology, and chemical structures) of nanotechnology adjuvants incorporated in the vaccines. Finally, we propose possible strategies to accelerate the clinical implementation of nanotechnology adjuvanted vaccines, such as in-depth elucidation of nano-immuno interactions, antigen identification and optimization by the deployment of high-dimensional multiomics analysis approaches, encouraging close collaborations among scientists from different scientific disciplines and aggressive exploration of novel nanotechnologies.

Polysaccharides-Naturally Occurring Immune Modulators

The prevention of disease and infection requires immune systems that operate effectively. This is accomplished by the elimination of infections and abnormal cells. Immune or biological therapy treats disease by either stimulating or inhibiting the immune system, dependent upon the circumstances. In plants, animals, and microbes, polysaccharides are abundant biomacromolecules. Due to the intricacy of their structure, polysaccharides may interact with and impact the immune response; hence, they play a crucial role in the treatment of several human illnesses. There is an urgent need for the identification of natural biomolecules that may prevent infection and treat chronic disease. This article addresses some of the naturally occurring polysaccharides of known therapeutic potential that have already been identified. This article also discusses extraction methods and immunological modulatory capabilities.

Biodistribution and Adjuvant Effect of an Intranasal Vaccine Based on Chitosan Nanoparticles against Paracoccidioidomycosis

Paracoccidioidomycosis (PCM) is a fungal infection caused by the thermodimorphic Paracoccidioides sp. PCM mainly affects the lungs, but, if it is not contained by the immune response, the disease can spread systemically. An immune response derived predominantly from Th1 and Th17 T cell subsets facilitates the elimination of Paracoccidioides cells. In the present work, we evaluated the biodistribution of a prototype vaccine based on the immunodominant and protective P. brasiliensis P10 peptide within chitosan nanoparticles in BALB/c mice infected with P. brasiliensis strain 18 (Pb18). The generated fluorescent (FITC or Cy5.5) or non-fluorescent chitosan nanoparticles ranged in diameter from 230 to 350 nm, and both displayed a Z potential of +20 mV. Most chitosan nanoparticles were found in the upper airway, with smaller amounts localized in the trachea and lungs. The nanoparticles complexed or associated with the P10 peptide were able to reduce the fungal load, and the use of the chitosan nanoparticles reduced the necessary number of doses to achieve fungal reduction. Both vaccines were able to induce a Th1 and Th17 immune response. These data demonstrates that the chitosan P10 nanoparticles are an excellent candidate vaccine for the treatment of PCM.

Long-term exposure to house dust mites accelerates lung cancer development in mice

BACKGROUND

Individuals with certain chronic inflammatory lung diseases have a higher risk of developing lung cancer (LC). However, the underlying mechanisms remain largely unknown. Here, we hypothesized that chronic exposure to house dust mites (HDM), a common indoor aeroallergen associated with the development of asthma, accelerates LC development through the induction of chronic lung inflammation (CLI).  METHODS: The effects of HDM and heat-inactivated HDM (HI-HDM) extracts were evaluated in two preclinical mouse models of LC (a chemically-induced model using the carcinogen urethane and a genetically-driven model with oncogenic KrasG12D activation in lung epithelial cells) and on murine macrophages in vitro. Pharmacological blockade or genetic deletion of the Nod-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome, caspase-1, interleukin-1β (IL-1β), and C-C motif chemokine ligand 2 (CCL2) or treatment with an inhaled corticosteroid (ICS) was used to uncover the pro-tumorigenic effect of HDM.  RESULTS: Chronic intranasal (i.n) instillation of HDM accelerated LC development in the two mouse models. Mechanistically, HDM caused a particular subtype of CLI, in which the NLRP3/IL-1β signaling pathway is chronically activated in macrophages, and made the lung microenvironment conducive to tumor development. The tumor-promoting effect of HDM was significantly decreased by heat treatment of the HDM extract and was inhibited by NLRP3, IL-1β, and CCL2 neutralization, or ICS treatment.

CONCLUSIONS

Collectively, these data indicate that long-term exposure to HDM can accelerate lung tumorigenesis in susceptible hosts (e.g., mice and potentially humans exposed to lung carcinogens or genetically predisposed to develop LC).

Oral administration of hepcidin and chitosan benefits growth, immunity, and gut microbiota in grass carp (Ctenopharyngodon idella)

Intensive high-density culture patterns are causing an increasing number of bacterial diseases in fish. Hepcidin links iron metabolism with innate immunity in the process of resisting bacterial infection. In this study, the antibacterial effect of the combination of hepcidin (Cihep) and chitosan (CS) against Flavobacterium columnare was investigated. The dosing regimen was also optimized by adopting a feeding schedule of every three days and every seven days. After 56 days of feeding experiment, grass carp growth, immunity, and gut microbiota were tested. In vitro experiments, Cihep and CS can regulate iron metabolism and antibacterial activity, and that the combination of Cihep and CS had the best protective effect. In vivo experiments, Cihep and CS can improve the growth index of grass carp. After challenge with Flavobacterium columnare, the highest survival rate was observed in the Cihep+CS-3d group. By serum biochemical indicators assay and Prussian blue staining, Cihep and CS can increase iron accumulation and decrease serum iron levels. The contents of lysozyme and superoxide dismutase in Cihep+CS-3d group increased significantly. Meanwhile, Cihep and CS can significantly reduce the pathological damage of gill tissue. The 16S rRNA sequencing results showed that Cihep and CS can significantly increase the abundance and diversity of grass carp gut microbiota. These results indicated that the protective effect of consecutive 3-day feeding followed by a 3-day interval was better than that of consecutive 7-day feeding followed by a 7-day interval, and that the protective effect of Cihep in combination with chitosan was better than that of Cihep alone. Our findings optimize the feeding pattern for better oral administration of Cihep in aquaculture.

Topical reinforcement of the cervical mucus barrier to sperm

Close to half of the world's pregnancies are still unplanned, reflecting a clear unmet need in contraception. Ideally, a contraceptive would provide the high efficacy of hormonal treatments, without systemic side effects. Here, we studied topical reinforcement of the cervical mucus by chitosan mucoadhesive polymers as a form of female contraceptive. Chitosans larger than 7 kDa effectively cross-linked human ovulatory cervical mucus to prevent sperm penetration in vitro. We then demonstrated in vivo using the ewe as a model that vaginal gels containing chitosan could stop ram sperm at the entrance of the cervical canal and prevent them from reaching the uterus, whereas the same gels without chitosan did not substantially limit sperm migration. Chitosan did not affect sperm motility in vitro or in vivo, suggesting reinforcement of the mucus physical barrier as the primary mechanism of action. The chitosan formulations did not damage or irritate the ewe vaginal epithelium, in contrast to nonoxynol-9 spermicide. The demonstration that cervical mucus can be reinforced topically to create an effective barrier to sperm may therefore form the technological basis for muco-cervical barrier contraceptives with the potential to become an alternative to hormonal contraceptives.

The evolution of the global COVID-19 epidemic in Morocco and understanding the different therapeutic approaches of chitosan in the control of the pandemic

In 2020, Coronavirus disease (COVID-19), a new viral respiratory disease caused by a virus that belongs to Coronaviridae family, has been identified. It is a very severe flu that negatively affects the functions of the lung and other respiratory organs. COVID-19 virus can be transmitted between people either by touching an infected person or by direct contact with their respiratory droplets. Therefore, the COVID-19 virus has become a global concern due to its rapid spread and severity. Based on the World Health Organization report from 2 March 2020 to 24 October 2022, the total infected cases and deaths in Morocco are around 1,265,389 (3.46%) and 16,280 (0.04%), respectively. Recently, some scientists have found that chitosan, a polymer existed in nature, can inhibit COVID-19 infection and repair damaged tissue. Therefore, understanding chitosan mechanisms in controlling COVID-19, might lead to innovative strategies in the medical field, such as developing drugs against SARS-CoV-2, and replacing vaccines, which have negative side effects. This review aims to show the evolution of the COVID-19 pandemic worldwide, specifically in Morocco, its pathophysiology, and its ability to silence the immune system. This review also provides an overview of the treatments and measures applied to protect human beings and how chitosan acts and controls COVID-19.

Current strategies employed in the manipulation of gene expression for clinical purposes

Abnormal gene expression level or expression of genes containing deleterious mutations are two of the main determinants which lead to genetic disease. To obtain a therapeutic effect and thus to cure genetic diseases, it is crucial to regulate the host's gene expression and restore it to physiological conditions. With this purpose, several molecular tools have been developed and are currently tested in clinical trials. Genome editing nucleases are a class of molecular tools routinely used in laboratories to rewire host's gene expression. Genome editing nucleases include different categories of enzymes: meganucleses (MNs), zinc finger nucleases (ZFNs), clustered regularly interspaced short palindromic repeats (CRISPR)- CRISPR associated protein (Cas) and transcription activator-like effector nuclease (TALENs). Transposable elements are also a category of molecular tools which includes different members, for example Sleeping Beauty (SB), PiggyBac (PB), Tol2 and TcBuster. Transposons have been used for genetic studies and can serve as gene delivery tools. Molecular tools to rewire host's gene expression also include episomes, which are divided into different categories depending on their molecular structure. Finally, RNA interference is commonly used to regulate gene expression through the administration of small interfering RNA (siRNA), short hairpin RNA (shRNA) and bi-functional shRNA molecules. In this review, we will describe the different molecular tools that can be used to regulate gene expression and discuss their potential for clinical applications. These molecular tools are delivered into the host's cells in the form of DNA, RNA or protein using vectors that can be grouped into physical or biochemical categories. In this review we will also illustrate the different types of payloads that can be used, and we will discuss recent developments in viral and non-viral vector technology.

Polymeric Nanoparticles for Inhaled Vaccines

Many recent studies focus on the pulmonary delivery of vaccines as it is needle-free, safe, and effective. Inhaled vaccines enhance systemic and mucosal immunization but still faces many limitations that can be resolved using polymeric nanoparticles (PNPs). This review focuses on the use of properties of PNPs, specifically chitosan and PLGA to be used in the delivery of vaccines by inhalation. It also aims to highlight that PNPs have adjuvant properties by themselves that induce cellular and humeral immunogenicity. Further, different factors influence the behavior of PNP in vivo such as size, morphology, and charge are discussed. Finally, some of the primary challenges facing PNPs are reviewed including formulation instability, reproducibility, device-related factors, patient-related factors, and industrial-level scale-up. Herein, the most important variables of PNPs that shall be defined in any PNPs to be used for pulmonary delivery are defined. Further, this study focuses on the most popular polymers used for this purpose.

Mixed lineage kinase-like protein protects against Clostridium perfringens infection by enhancing NLRP3 inflammasome-extracellular traps axis

Despite intense research in understanding Clostridium perfringens (C. perfringens) pathogenesis, the mechanisms by which it is cleared from the host are largely unclarified. In C. perfringens gas gangrene and enterocolitis model, Mlkl ^-/- mice, lacking mixed lineage kinase-like protein (MLKL), are more susceptible to C. perfringens infection. Mlkl deficiency results in a defect in inflammasome activation, and IL-18 and IL-1β releases. Exogenous administration of recombinant IL-18 is able to rescue the susceptibility of Mlkl ^-/- mice. Notably, K⁺ efflux-dependent NLRP3 inflammasome signaling downstream of active MLKL promotes bacterial killing and clearance. Interestingly, the defect of bactericidal activity is also mediated by decreased classical extracellular trap formation in the absence of Mlkl. Our results demonstrate that MLKL mediates extracellular trap formation in a NLRP3 inflammasome-dependent manner. These findings highlight the requirement of MLKL for host defense against C. perfringens infection through enhancing NLRP3 inflammasome-extracellular traps axis.

Physical, Chemical, and Biological Properties of Chitosan-Coated Alginate Microparticles Loaded with Porcine Interleukin-1β: A Potential Protein Adjuvant Delivery System

We previously developed chicken interleukin-1β (IL-1β) mutants as single-dose adjuvants that induce protective immunity when co-administered with an avian vaccine. However, livestock such as pigs may require a vaccine adjuvant delivery system that provides long-lasting protection to reduce the need for successive booster doses. Therefore, we developed chitosan-coated alginate microparticles as a carrier for bovine serum albumin (BSA) or porcine IL-1β (pIL-1β) and assessed their physical, chemical, and biological properties. Electrospraying of the BSA-loaded alginate microparticles (BSA/ALG MPs) resulted in an encapsulation efficiency of 50%, and those MPs were then coated with chitosan (BSA/ALG/CHI MPs). Optical and scanning electron microscopy, zeta potential analysis, and Fourier transform infrared spectroscopy were used to characterize these MPs. The BSA encapsulation parameters were applied to ALG/CHI MPs loaded with pIL-1β, which were not cytotoxic to porcine fibroblasts but had enhanced bio-activity over unencapsulated pIL-1β. The chitosan layer of the BSA/ALG/CHI MPs prevented burst release and facilitated sustained release of pIL-1β for at least 28 days. In conclusion, BSA/ALG/CHI MPs prepared as a carrier for pIL-1β may be used as an adjuvant for the formulation of pig vaccines.

Immunostimulatory Polymers as Adjuvants, Immunotherapies, and Delivery Systems

Activating innate immunity in a controlled manner is necessary for the development of next-generation therapeutics. Adjuvants, or molecules that modulate the immune response, are critical components of vaccines and immunotherapies. While small molecules and biologics dominate the adjuvant market, emerging evidence supports the use of immunostimulatory polymers in therapeutics. Such polymers can stabilize and deliver cargo while stimulating the immune system by functioning as pattern recognition receptor (PRR) agonists. At the same time, in designing polymers that engage the immune system, it is important to consider any unintended initiation of an immune response that results in adverse immune-related events. Here, we highlight biologically derived and synthetic polymer scaffolds, as well as polymer–adjuvant systems and stimuli-responsive polymers loaded with adjuvants, that can invoke an immune response. We present synthetic considerations for the design of such immunostimulatory polymers, outline methods to target their delivery, and discuss their application in therapeutics. Finally, we conclude with our opinions on the design of next-generation immunostimulatory polymers, new applications of immunostimulatory polymers, and the development of improved preclinical immunocompatibility tests for new polymers.

Nanosafety: An Evolving Concept to Bring the Safest Possible Nanomaterials to Society and Environment

The use of nanomaterials has been increasing in recent times, and they are widely used in industries such as cosmetics, drugs, food, water treatment, and agriculture. The rapid development of new nanomaterials demands a set of approaches to evaluate the potential toxicity and risks related to them. In this regard, nanosafety has been using and adapting already existing methods (toxicological approach), but the unique characteristics of nanomaterials demand new approaches (nanotoxicology) to fully understand the potential toxicity, immunotoxicity, and (epi)genotoxicity. In addition, new technologies, such as organs-on-chips and sophisticated sensors, are under development and/or adaptation. All the information generated is used to develop new in silico approaches trying to predict the potential effects of newly developed materials. The overall evaluation of nanomaterials from their production to their final disposal chain is completed using the life cycle assessment (LCA), which is becoming an important element of nanosafety considering sustainability and environmental impact. In this review, we give an overview of all these elements of nanosafety.

Intranasal Delivery of Thermostable Subunit Vaccine for Cross-Reactive Mucosal and Systemic Antibody Responses Against SARS-CoV-2

Despite the remarkable efficacy of currently approved COVID-19 vaccines, there are several opportunities for continued vaccine development against SARS-CoV-2 and future lethal respiratory viruses. In particular, restricted vaccine access and hesitancy have limited immunization rates. In addition, current vaccines are unable to prevent breakthrough infections, leading to prolonged virus circulation. To improve access, a subunit vaccine with enhanced thermostability was designed to eliminate the need for an ultra-cold chain. The exclusion of infectious and genetic materials from this vaccine may also help reduce vaccine hesitancy. In an effort to prevent breakthrough infections, intranasal immunization to induce mucosal immunity was explored. A prototype vaccine comprised of receptor-binding domain (RBD) polypeptides formulated with additional immunoadjuvants in a chitosan (CS) solution induced high levels of RBD-specific antibodies in laboratory mice after 1 or 2 immunizations. Antibody responses were durable with high titers persisting for at least five months following subcutaneous vaccination. Serum anti-RBD antibodies contained both IgG1 and IgG2a isotypes suggesting that the vaccine induced a mixed Th1/Th2 response. RBD vaccination without CS formulation resulted in minimal anti-RBD responses. The addition of CpG oligonucleotides to the CS plus RBD vaccine formulation increased antibody titers more effectively than interleukin-12 (IL-12). Importantly, generated antibodies were cross-reactive against RBD mutants associated with SARS-CoV-2 variants of concern, including alpha, beta and delta variants, and inhibited binding of RBD to its cognate receptor angiotensin converting enzyme 2 (ACE2). With respect to stability, vaccines did not lose activity when stored at either room temperature (21-22°C) or 4°C for at least one month. When delivered intranasally, vaccines induced RBD-specific mucosal IgA antibodies, which may protect against breakthrough infections in the upper respiratory tract. Altogether, data indicate that the designed vaccine platform is versatile, adaptable and capable of overcoming key constraints of current COVID-19 vaccines.

Resolving the Mutually Exclusive Immune Responses of Chitosan with Nanomechanics and Immunological Assays

Multifaceted functions displayed by both pro- and anti-inflammatory properties of chitosan hinder its effective development as an immunomodulatory agent. Herein, the contributions of the bending stiffness of chitosan with regard to its immune regulatory properties toward inflammation are investigated. The anti-inflammatory properties of chitosan molecular weight (MW) with a shorter (≈1 kDa) or longer (≈15 kDa) than the persistent length (L_P ) are compared using immunological assays and nanomechanics-based experiments on the surface forces apparatus (SFA). Interestingly, 1 kDa chitosan significantly enhances the generation of anti-inflammatory regulatory T cells (Tregs) through the Dectin-1-dependent pattern recognition receptor (PRR) on antigen-presenting cells. SFA analyses also show a similar trend of interaction forces between chitosan and diverse PRRs depending on their MW. The results obtained in the immunological and nanomechanical experiments are consistent and imply that the binding features of PRRs vary depending on the MW of chitosan, which may alter immune activity. In accordance, in vivo administration of only 1 kDa represses inflammatory responses and suppresses the progression of experimental colitis. This study elucidates a previously unexplored bending stiffness-dependent immune regulatory property of chitosan and suggests the applicability of low MW (rod-like) chitosan as a pharmaceutical ingredient to treat diverse inflammatory disorders.

Chemical and Biomolecular Strategies for STING Pathway Activation in Cancer Immunotherapy

The stimulator of interferon genes (STING) cellular signaling pathway is a promising target for cancer immunotherapy. Activation of the intracellular STING protein triggers the production of a multifaceted array of immunostimulatory molecules, which, in the proper context, can drive dendritic cell maturation, antitumor macrophage polarization, T cell priming and activation, natural killer cell activation, vascular reprogramming, and/or cancer cell death, resulting in immune-mediated tumor elimination and generation of antitumor immune memory. Accordingly, there is a significant amount of ongoing preclinical and clinical research toward further understanding the role of the STING pathway in cancer immune surveillance as well as the development of modulators of the pathway as a strategy to stimulate antitumor immunity. Yet, the efficacy of STING pathway agonists is limited by many drug delivery and pharmacological challenges. Depending on the class of STING agonist and the desired administration route, these may include poor drug stability, immunocellular toxicity, immune-related adverse events, limited tumor or lymph node targeting and/or retention, low cellular uptake and intracellular delivery, and a complex dependence on the magnitude and kinetics of STING signaling. This review provides a concise summary of the STING pathway, highlighting recent biological developments, immunological consequences, and implications for drug delivery. This review also offers a critical analysis of an expanding arsenal of chemical strategies that are being employed to enhance the efficacy, safety, and/or clinical utility of STING pathway agonists and lastly draws attention to several opportunities for therapeutic advancements.

Chitosan based nanoformulation expressing miR-155 as a promising adjuvant to enhance Th1-biased immune responses

BACKGROUND AND AIM

MiR-155 could act as a key modulator of different aspects of immune system including Th1 responses. In this study, we designed chitosan nanoparticles containing miR-155-expressing plasmid and explored their effects as an adjuvant to enhance Th1 responses for potential future application against intracellular pathogens.

METHODS

Nanoparticles were formulated by complex coacervation method and characterized for physicochemical and functional characteristics. Transfection efficiency in Raw 264.7 cells, effects on miR-155 target genes and NO production were evaluated. The prepared nanoparticles were co-administered as an adjuvant with ovalbumin to immunize mice and finally production of IFN-γ and IL-4 were measured by ELISA in splenocyte recall responses.

RESULTS

The prepared nanoparticles had the mean size of 244 nm and zeta potential of +17 mV, respectively. Electrophoresis analysis indicated the high capability of nanoparticles to protect the plasmid from DNaseI degradation. Furthermore, nanoparticles showed an appropriate transfection efficiency in Raw 264.7 cells and could downregulate the expression of miR-155 target genes and also upregulate NO production. In vivo immunization examinations revealed successful shift of T cell responses toward Th1.

CONCLUSION

Our data suggests the high potential of chitosan nanoparticles containing miR-155-expressing plasmid as an adjuvant for significantly enhanced Th1-biased immune responses upon immunization with a given antigen.

Reviewing the biological activity of chitosan in the mucosa: Focus on intestinal immunity

Chitosan is a polymer derived from the partial deacetylation of chitin with particular characteristics, such as mucoadhesiveness, tolerability, biocompatibility and biodegradability. Biomedical uses of chitosan cover a wide spectrum of applications as dietary fiber, immunoadjuvant and regulator of the intestinal microbiota or delivery agent. Chemical modification of chitosan is feasible because its reactive amino and hydroxyl groups can be modified by a diverse array of ligands, functional groups and molecules. This gives rise to numerous derivatives that allow different formulation types influencing their activity. Considering the multiple events resulting from the interaction with mucosal tissues, chitosan is a singular candidate for strategies targeting immune stimulation (i.e., tolerance induction, vaccination). Its role as a prebiotic and probiotic carrier represents an effective option to manage intestinal dysbiosis. In the intestinal scenario where the exposure of the immune system to a wide variety of antigens is permanent, chitosan increases IgA levels and favors a tolerogenic environment, thus becoming a key ally for host homeostasis.

Advances in Encapsulation and Delivery Strategies for Islet Transplantation

Type 1 diabetes mellitus (T1DM) is a chronic metabolic disease caused by the destruction of pancreatic β-cells in response to autoimmune reactions. Shapiro et al. conducted novel islet transplantation with a glucocorticoid-free immunosuppressive agent in 2000 and achieved great success; since then, islet transplantation has been increasingly regarded as a promising strategy for the curative treatment of T1DM. However, many unavoidable challenges, such as a lack of donors, poor revascularization, blood-mediated inflammatory reactions, hypoxia, and side effects caused by immunosuppression have severely hindered the widespread application of islet transplantation in clinics. Biomaterial-based encapsulation and delivery strategies are proposed for overcoming these obstacles, and have demonstrated remarkable improvements in islet transplantation outcomes. Herein, the major problems faced by islet transplantation are summarized and updated biomaterial-based strategies for islet transplantation, including islet encapsulation across different scales, delivery of stem cell-derived beta cells, co-delivery of islets with accessory cells and immunomodulatory molecules are highlighted.

Shell-mediated phagocytosis to reshape viral-vectored vaccine-induced immunity

Adenovirus (Ad) has been extensively developed as a gene delivery vector, but the potential side effect caused by systematic immunization remains one major obstacle for its clinical application. Needle-free mucosal immunization with Ad-based vaccine shows advantages but still faces poor mucosal responses. We herein report that the chemical engineering of single live viral-based vaccine effectively modulated the location and pattern of the subsequently elicited immunity. Through precisely assembly of functional materials onto single live Ad particle, the modified virus entered host cell in a phagocytosis-dependent manner, which is completely distinct from the receptor-mediated entry of native Ad. RNA-Seq data further demonstrated that the modified Ad-induced innate immunity was sharply reshaped via phagocytosis-related pathway, therefore promoting the activation and mature of antigen presentation cells (APC). Moreover, the functional shell enabled the modified Ad-based vector with enhanced muco-adhesion to nasal tissues in mice, and then prolonged resident time onto mucosal surface, leading to the robust mucosal IgA production and T cell immunity at local and even remote mucosal-associated lymphoid tissues. This study demonstrated that vaccine-induced immunity can be well modulated by chemistry engineering, and this method provides the rational design for needle-free mucosa-targeting vaccine against a variety of emerging infectious diseases.

Analysis of Safety and Effectiveness of Sodium Alginate/Poly(γ-glutamic acid) Microspheres for Rapid Hemostasis

Most preventable deaths after trauma are related to hemorrhage and occur early after injury. Timely hemostatic treatment is essential to minimize blood loss and improve survival. Among the various treatment methods, the most economical and effective is to use a hemostatic agent. A powdered hemostatic agent can be used for wounds of any shape or depth with high compactness and excellent accumulation effect. Herein, we chose the natural, hydrophilic polymer poly(γ-glutamic acid) (γ-PGA) to form composite hemostatic microspheres with sodium alginate (SA), which show good biocompatibility, water absorptivity, and viscosity. The morphology and structure of the hemostatic microspheres were determined using Fourier transform infrared spectroscopy and scanning electron microscopy. The overall safety, hemolysis, pyrogenic, and intradermal irritation tests were examined. The relationship between hemostatic pressure and hemostatic time during microsphere use was also measured. The hemostatic effect was analyzed with a liver, spleen, and femoral artery bleeding model. The composite microspheres were well tolerated in vivo and exhibited better hemostatic effects in animal experiments than a microporous polysaccharide powder compound. Research results showed that SA/γ-PGA microspheres are materials with good hemostatic effect, high safety, and great potential in clinical applications.

Non-viral Vectors in Gene Therapy: Recent Development, Challenges, and Prospects

Gene therapy has been experiencing a breakthrough in recent years, targeting various specific cell groups in numerous therapeutic areas. However, most recent clinical studies maintain the use of traditional viral vector systems, which are challenging to manufacture cost-effectively at a commercial scale. Non-viral vectors have been a fast-paced research topic in gene delivery, such as polymers, lipids, inorganic particles, and combinations of different types. Although non-viral vectors are low in their cytotoxicity, immunogenicity, and mutagenesis, attracting more and more researchers to explore the promising delivery system, they do not carry ideal characteristics and have faced critical challenges, including gene transfer efficiency, specificity, gene expression duration, and safety. This review covers the recent advancement in non-viral vectors research and formulation aspects, the challenges, and future perspectives.

Chitin and chitosan as tools to combat COVID-19: A triple approach

The progressive and fatal outbreak of the newly emerged coronavirus, SARS-CoV-2, necessitates rigorous collaboration of all health care systems and researchers from all around the world to bring such a devastating pandemic under control. As there is so far no officially approved drug or ideal vaccine for this disease, investigations on this infectious disease are actively pursued. Chitin and chitosan have shown promising results against viral infections. In this review, we first delve into the problematic consequences of viral pandemics followed by an introduction on SARS-CoV-2 taxonomical classification. Then, we elaborate on the immunology of COVID-19. Common antiviral therapies and their related limitations are described and finally, the potential applicability of chitin and chitosan to fight this overwhelming viral pandemic is addressed.

Alginate-chitosan microcapsules improve vaccine potential of gamma-irradiated Listeria monocytogenes against listeriosis in murine model

Listeria monocytogenes is a cause of infectious food-borne disease in humans, characterized by neurological manifestations, abortion, and neonatal septicemia. It is intracellular bacterium, which limits the development of protective inactivated vacines. Adjuvants capable of stimulating cellular immune response are important tools for developing novel vaccines against intracellular bacteria. The aim of this study was to evaluate the vaccine potential of L. monocytogenes inactivated by gamma irradiation (KLM-γ) encapsulated in alginate microcapsules associated or not with chitosan against listeriosis in the murine model. At the fourth day after challenge there was a reduction in bacterial recovery in mice vaccinated with KLM-γ encapsulated with alginate or alginate-chitosan, with lower bacterial loads in the spleen (10 fold) and liver (100 fold) when compared to non-vaccinated mice. In vitro stimulation of splenocytes from mice vaccinated with alginate-chitosan-encapsulated KLM-γ resulted in lymphocyte proliferation, increase of proportion of memory CD4⁺ and CD8⁺ T cell and production of IL-10 and IFN-γ. Interestingly, the group vaccinated with alginate-chitosan-encapsulated KLM-γ had increased survival to lethal infection with lower L. monocytogenes-induced hepatic inflammation and necrosis. Therefore, KLM-γ encapsulation with alginate-chitosan proved to have potential for development of novel and safe inactivated vaccine formulations against listeriosis.

Synthesis of Biotin-Tagged Chitosan Oligosaccharides and Assessment of Their Immunomodulatory Activity

Chitin, a polymer of β-(1→4)-linked N-acetyl-d-glucosamine, is one of the main polysaccharide components of the fungal cell wall. Its N-deacetylated form, chitosan, is enzymatically produced in the cell wall by chitin deacetylases. It exerts immunomodulative, anti-inflammatory, anti-cancer, anti-bacterial, and anti-fungal activities with various medical applications. To study the immunobiological properties of chitosan oligosaccharides, we synthesized a series of β-(1→4)-linked N-acetyl-d-glucosamine oligomers comprising 3, 5, and 7 monosaccharide units equipped with biotin tags. The key synthetic intermediate employed for oligosaccharide chain elongation, a disaccharide thioglycoside, was prepared by orthogonal glycosylation of a 4-OH thioglycoside acceptor with a glycosyl trichloroacetimidate bearing the temporary 4-O-tert-butyldimethylsilyl group. The use of silyl protection suppressed aglycon transfer and provided a high yield for the target disaccharide donor. Using synthesized chitosan oligomers, as well as previously obtained chitin counterparts, the immunobiological relationship between these synthetic oligosaccharides and RAW 264.7 cells was studied in vitro. Evaluation of cell proliferation, phagocytosis, respiratory burst, and Th1, Th2, Th17, and Treg polarized cytokine expression demonstrated effective immune responsiveness and immunomodulation in RAW 264.7 cells exposed to chitin- and chitosan-derived oligosaccharides. Macrophage reactivity was accompanied by significant inductive dose- and structure-dependent protective Th1 and Th17 polarization, which was greater with exposure to chitosan- rather than chitin-derived oligosaccharides. Moreover, no antiproliferative or cytotoxic effects were observed, even following prolonged 48 h exposure. The obtained results demonstrate the potent immunobiological activity of these synthetically prepared chito-oligosaccharides.

Molecularly Distinct NLRP3 Inducers Mediate Diverse Ratios of Interleukin-1β and Interleukin-18 from Human Monocytes

Inflammasomes cleave and activate interleukin- (IL-) 1β and IL-18 which have both shared and unique biological functions. IL-1β is an important mediator of the acute phase response to infections and tissue damage, whereas IL-18 takes part in activation and tailoring of the adaptive immune response. While IL-1β has served as the prototypic indicator of inflammasome activation, few studies have compared the potential differences in IL-1β and IL-18 production during inflammasome activation. Since these cytokines partake in different immune pathways, the involvement of inflammasome activity in different conditions needs to be described beyond IL-1β production alone. To address a potential heterogeneity in inflammasome functionality, ATP, chitosan, or silica oxide (SiO₂) were used to induce NLRP3 inflammasome activation in THP-1 cells and the subsequent outcomes were quantified. Despite using doses of the inflammasome inducers yielding similar release of IL-1β, SiO₂-stimulated cells showed a lower concentration of released IL-18 compared to ATP and chitosan. Hence, the cells stimulated with SiO₂ responded with a distinctly different IL-18 : IL-1β ratio. The difference in the IL-18 : IL-1β ratio for SiO₂ was constant over different doses. While all downstream responses were strictly dependent on a functional NLRP3 inflammasome, the differences did not depend on the level of gene expression, caspase-1 activity, or pyroptosis. We suggest that the NLRP3 inflammasome response should be considered a dynamic process, which can be described by taking the ratio between IL-1β and IL-18 into account and moving away from an on/off perspective of inflammasome activation.

Sulfated chitosan rescues dysfunctional macrophages and accelerates wound healing in diabetic mice

Emerging evidence suggests that dysfunctional macrophages can cause chronic inflammation and impair tissue regeneration in diabetic wounds. Therefore, improving macrophage behaviors and functions may improve therapeutic outcomes of current treatments in diabetic wounds. Herein, we present a sulfated chitosan (SCS)-doped Collagen type I (Col I/SCS) hydrogel as a candidate for diabetic wound treatments, and assess its efficacy using streptozocin (STZ)-induced diabetic wound model. Results showed that Col I/SCS hydrogel significantly improved wound closure rate, collagen deposition, and revascularization in diabetic wounds. Flow cytometry analysis and immunofluorescent staining analysis showed that the Col I/SCS hydrogel accelerated the resolution of excessive inflammation by reducing the polarization of M1-like macrophages in chronic diabetic wounds. In addition, ELISA analysis revealed that the Col I/SCS hydrogel reduced the production of pro-inflammatory interleukin (IL)-6 and increased the production of anti-inflammatory cytokines including IL-4 and transforming growth factor-beta 1 (TGF-β1) during wound healing. Moreover, the Col I/SCS hydrogel enhanced the transdifferentiation of macrophages into fibroblasts, which enhanced the formation of collagen and the extracellular matrix (ECM) in wound tissue. We highlight a potential application of manipulating macrophages behaviors in the pathological microenvironment via materials strategy. STATEMENT OF SIGNIFICANCE: Improving the chronic inflammatory microenvironment of diabetic wounds by regulating macrophage behaviors has been of wide concern in recent years. We designed a Col I/SCS hydrogel based on Collagen type I and sulfated chitosan (SCS) without exogenous cells or cytokines, which could significantly improve angiogenesis and resolve chronic inflammation in diabetic wounds, and hence accelerate diabetic wound healing. The Col I/SCS hydrogel could facilitate the polarization of M1-to-M2 macrophages and activate the transdifferentiation of macrophages to fibroblasts. Additionally, the Col I/SCS hydrogel also equilibrated the content of pro-inflammatory and anti-inflammatory cytokines. This strategy may afford a new avenue to improve macrophage functions and accelerate diabetic chronic wound healing.

Anti-Inflammatory Activity of Chitosan and 5-Amino Salicylic Acid Combinations in Experimental Colitis

Chitosan is used in various drug delivery approaches as a pharmaceutical excipient. Although its potential as an immunomodulatory agent has been reported, its use in this capacity has not been fully explored. The efficacy of chitosan as an active pharmacological agent, particularly in anti-inflammatory therapy in inflammatory bowel diseases (IBD), was investigated in this study. The potential impact of the molecular weight (MW) and degree of deacetylation (DD) of chitosan was investigated together with 5-amino salicylic acid (5-ASA) for its efficacy in a combination anti-inflammatory therapy in murine experimental colitis. Such a combination would potentially be developed into novel dual strategies whereby chitosan acts as a mucoadhesive excipient as well as provide an additional anti-inflammatory benefit. Chitosan grades with different MW and DD were administered intrarectally alone or in combination with 5-ASA to colitis mice for 3 days. Myeloperoxidase (MPO) and alkaline phosphatase (ALP) activity and tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β) and nuclear factor kappa-B (NF-κB) levels were assessed from the colon. Intrarectal treatment of colitis with 30 mg/kg chitosan alone and with 30 mg/kg 5-ASA for 3 days led to a significant decrease in MPO, ALP, TNF-α, IL-6, IL-1β and NF-κB in colitis mice compared to untreated mice. Surprisingly, the efficacy of chitosan as an anti-inflammatory polymer was relatively independent from its structural properties, namely DD and MW. However, combinations of chitosan with 5-ASA showed a significant pharmacological improvement, whereby the additive anti-inflammatory efficacy observed shows the possibility of finetuning chitosan by combining it with anti-inflammatory agents to optimize its anti-inflammatory potential.

Inflammasome-Mediated Immunogenicity of Clinical and Experimental Vaccine Adjuvants

In modern vaccines, adjuvants can be sophisticated immunological tools to promote robust and long-lasting protection against prevalent diseases. However, there is an urgent need to improve immunogenicity of vaccines in order to protect mankind from life-threatening diseases such as AIDS, malaria or, most recently, COVID-19. Therefore, it is important to understand the cellular and molecular mechanisms of action of vaccine adjuvants, which generally trigger the innate immune system to enhance signal transition to adaptive immunity, resulting in pathogen-specific protection. Thus, improved understanding of vaccine adjuvant mechanisms may aid in the design of “intelligent” vaccines to provide robust protection from pathogens. Various commonly used clinical adjuvants, such as aluminium salts, saponins or emulsions, have been identified as activators of inflammasomes - multiprotein signalling platforms that drive activation of inflammatory caspases, resulting in secretion of pro-inflammatory cytokines of the IL-1 family. Importantly, these cytokines affect the cellular and humoral arms of adaptive immunity, which indicates that inflammasomes represent a valuable target of vaccine adjuvants. In this review, we highlight the impact of different inflammasomes on vaccine adjuvant-induced immune responses regarding their mechanisms and immunogenicity. In this context, we focus on clinically relevant adjuvants that have been shown to activate the NLRP3 inflammasome and also present various experimental adjuvants that activate the NLRP3-, NLRC4-, AIM2-, pyrin-, or non-canonical inflammasomes and could have the potential to improve future vaccines. Together, we provide a comprehensive overview on vaccine adjuvants that are known, or suggested, to promote immunogenicity through inflammasome-mediated signalling.

Induction of antibody responses in mice immunized intranasally with Type I interferon as adjuvant and synergistic effect of chitosan

Type I IFNs are a range of host-derived molecules with adjuvant potential; they have been used for many years in the treatment of cancer and viral hepatitis. Therefore, the safety of IFNs for human use has been established. In this study, we evaluated the mucosal adjuvanticity of IFN-β administered intranasally to mice with diphtheria toxoid, and suggested a method to improve its adjuvanticity. When IFN-β alone was used as a mucosal adjuvant, no clear results were obtained. However, simultaneous administration of IFN-β and chitosan resulted in an enhancement of the specific serum immunoglobulin G (IgG) and IgA antibody responses, the mucosal IgA antibody response, and antitoxin titers. Furthermore, the intranasal administration of IFN-α alone resulted in a greater increase in antibody titer than IFN-β, and a synergistic effect with chitosan was also observed. These findings suggest that intranasal administration of chitosan and Type I IFNs may display an effective synergistic mucosal adjuvant activity.