Chitosan-based particulate systems for drug and vaccine delivery in the treatment and prevention of neglected tropical diseases

Modified PEG-Lipids Enhance the Nasal Mucosal Immune Capacity of Lipid Nanoparticle mRNA Vaccines

BACKGROUND/OBJECTIVES

Omicron, the predominant variant of SARS-CoV-2, exhibits strong immune-evasive properties, leading to the reduced efficacy of existing vaccines. Consequently, the development of versatile vaccines is imperative. Intranasal mRNA vaccines offer convenient administration and have the potential to enhance mucosal immunity. However, delivering vaccines via the nasal mucosa requires overcoming complex physiological barriers. The aim of this study is to modify PEGylated lipids to enhance the mucosal immune efficacy of the vaccine.

METHODS

The PEGylated lipid component of lipid nanoparticle (LNP) delivery vectors was modified with chitosan or mannose to generate novel LNPs that enhance vaccine adhesion or targeting on mucosal surfaces. The impact of the mRNA encoding the receptor-binding domain of Omicron BA.4/BA.5 on the immune response was examined.

RESULTS

Compared to the unmodified LNP group, the IgG and IgA titers in the chitosan or mannose-modified LNP groups showed an increasing trend. The chitosan-modified group showed better effects. Notably, the PEGylated lipid with 1.5 mol% of chitosan modification produced high levels of IgG1 and IgG2a antibodies, promoting Th1/Th2 responses while also generating high levels of IgA, which can induce stronger cellular immunity, humoral immunity, and mucosal immunity.

CONCLUSIONS

The 1.5 mol% of chitosan-modified LNPs (mRNA-LNP-1.5CS) can serve as a safe and effective carrier for intranasal mRNA vaccines, offering a promising strategy for combating the Omicron variant.

Applications of Chitosan in Prevention and Treatment Strategies of Infectious Diseases

Chitosan is the most commonly investigated functional cationic biopolymer in a wide range of medical applications due to its promising properties such as biocompatibility, biodegradability, and bioadhesivity, as well as its numerous bioactive properties. Within the last three decades, chitosan and its derivatives have been investigated as biomaterials for drug and vaccine delivery systems, besides for their bioactive properties. Due to the functional groups in its structure, it is possible to tailor the delivery systems with desired properties. There has been a great interest in the application of chitosan-based systems also for the prevention and treatment of infectious diseases, specifically due to their antimicrobial, antiviral, and immunostimulatory effects. In this review, recent applications of chitosan in the prevention and treatment of infectious diseases are reviewed, and possibilities and limitations with regards to technical and regulatory aspects are discussed. Finally, the future perspectives on utilization of chitosan as a biomaterial are discussed.

Encapsulation of Citrus sinensis essential oil and R-limonene in lipid nanocarriers: A potential strategy for the treatment of leishmaniasis

Leishmaniases, a group of neglected tropical diseases caused by an intracellular parasite of the genus Leishmania, have significant impacts on global health. Current treatment options are limited due to drug resistance, toxicity, and high cost. This study aimed to develop nanostructured lipid carriers (NLCs) for delivering Citrus sinensis essential oil (CSEO) and its main constituent, R-limonene, against leishmaniasis. The influence of surface-modified NLCs using chitosan was also examined. The NLCs were prepared using a warm microemulsion method, and surface modification with chitosan was achieved through electrostatic interaction. These nanocarriers were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy, and dynamic light scattering (DLS). In vitro cytotoxicity was assessed in L929 and RAW 264.7 cells, and leishmanicidal activity was evaluated against promastigote and amastigote forms. The NLCs were spherical, with particle sizes ranging from 97.9 nm to 111.3 nm. Chitosan-coated NLCs had a positive surface charge, with zeta potential values ranging from 45.8 mV to 59.0 mV. Exposure of L929 cells to NLCs resulted in over 70 % cell viability. Conversely, surface modification significantly reduced the viability of promastigotes (93 %) compared to free compounds. Moreover, chitosan-coated NLCs presented a better IC50 against the amastigote forms than uncoated NLCs. Taken together, these findings demonstrate the feasibility of using NLCs to overcome the limitations of current leishmaniasis treatments, warranting further research.

Polydopamine-based nano adjuvant as a promising vaccine carrier induces significant immune responses against Acinetobacter baumannii-associated pneumonia

The objective of this study was to assess the effectiveness of polydopamine nanoparticles (PDANPs) as a delivery system for intranasal antigen administration to prevent Acinetobacter baumannii (A. baumannii)-associated pneumonia. In the in vitro phase, the conserved outer membrane protein 22 (Omp22)-encoding gene of A. baumannii was cloned, expressed, and purified, resulting in the production of recombinant Omp22 (rOmp22), which was verified using western blot. PDANPs were synthesized using dopamine monomers and loaded with rOmp22 through physical adsorption. The rOmp22-loaded PDANPs were characterized in terms of size, size distribution, zeta potential, field emission scanning electron microscopy (FESEM), loading capacity, Fourier transform infrared spectroscopy (FTIR), release profile, and cytotoxicity. In the in vivo phase, the adjuvant effect of rOmp22-loaded PDANPs was evaluated in terms of eliciting immune responses, including humoral and cytokine levels (IL-4, IL-17, and IFN-γ), as well as protection challenge. The rOmp22-loaded PDANPs were spherical with a size of 205 nm, a zeta potential of -14 mV, and a loading capacity of approximately 35.7 %. The released rOmp22 from nontoxic rOmp22-loaded PDANPs over 20 days was approximately 41.5 %, with preserved rOmp22 integrity. The IgG2a/IgG1 ratio and IFN-γ levels were significantly higher in immunized mice with rOmp22-loaded-PDANPs than in rOmp22-alum, naive Omp22, and control groups. Furthermore, rOmp22-loaded PDANPs induced effective protection against infection in the experimental challenge and showed more normal structures in the lung histopathology assay. The results of this study suggest the potential of PDANPs as a nano-adjuvant for inducing strong immune responses to combat A. baumannii.

Bone-Adhesive Hydrogel for Effective Inhibition of M. tuberculosis and Osteoblast Regeneration

Currently, bone tuberculosis (TB) treatment largely involves lifelong drug prescriptions and surgical intervention, resulting in poor quality of life for patients. Therefore, the fabrication of injectable scaffolds to form a solid framework around the defective bone region is gaining importance over the extensive use of antimicrobial inhibitors. Herein, we synthesized a novel bone-adhesive and thermoresponsive hydrogel via conjugation of poly(N-isopropylacrylamide-co-glycidyl methacrylate) (PNIPAM-co-GMA) and cysteine (CYS). Thiolation of the polymer enables chemical cross-linking with the bone glycoprotein, enhancing bone adhesion and permitting control of scaffold retention time. The PNIPAM-co-GMA-CYS hydrogel shows higher cross-linking behavior at 37 °C, forms a strong gel in 260 s, and has 151 kPa adhesion strength on cortical bone. The lead compounds 5-methyl-5H-[1,2,4]triazino[5,6-b]indole-3-thiol (MTIT) and N-tert-butyl-4-methyl-6-(5-methyl-5H-[1,2,4]triazino[5,6-b]indol-3-ylthio)pyrimidin-2-amine (TMTIPA) were identified by a high-throughput screening method. Effective MTIT and TMTIPA are encapsulated in bone-adhesive hydrogel separately, and both have a high release rate above >70% in 180 h. The MTIT- and TMTIPA-loaded PNIPAM-co-GMA-CYS showed an excellent bactericidal effect, reducing the relative intracellular bacterial survival in macrophages. Furthermore, the as-synthesized hydrogel has outstanding mechanical and biocompatibility properties to become a bone-replacing material and provide support to promote bone repair. This work presents a novel bone-adhesive PNIPAM-co-GMA-CYS for the sustained release of lead compounds toward promising alternative bone TB treatment.

Challenges and Prospective of Enhancing Hydatid Cyst Chemotherapy by Nanotechnology and the Future of Nanobiosensors for Diagnosis

Hydatid cysts have been widely recognized for decades as a common medical problem that affects millions of people. A revolution in medical treatment may be on the prospect of nanotechnology enhancing chemotherapy against hydatid cysts. An overview of nanotechnology's impact on chemotherapeutics is presented in the current review. It discusses some of the challenges as well as some of the opportunities. The application of nanotechnology to enhance chemotherapy against hydatid cysts is what this review will explore. Nanotechnology is a critical component of delivering therapeutic agents with greater precision and efficiency and targeting hydatid cysts with better efficacy, and minimizing interference with surrounding tissue. However, there are biodistribution challenges, toxicity, and resistance problems associated with nanotherapeutics. Additionally, nanobiosensors are being investigated to enable the early diagnosis of hydatid cysts. A nanobiosensor can detect hydatid cysts by catching them early, non-invasively, rapidly, and accurately. The sensitivity and specificity of diagnostic tests can be enhanced with nanobiosensors because they take advantage of the unique properties of nanomaterials. By providing more precise and customized treatment options for hydatid cysts, nanotechnology may improve therapeutic options and strategies for diagnosing the disease. In conclusion, treatment with nanotechnology to treat hydatid cysts is potentially effective but presents many obstacles. Furthermore, nanobiosensors are being integrated into diagnostic techniques, as well as helping to diagnose patients earlier and more accurately.

Nano-adjuvanted dry powder vaccine for the mucosal immunization against airways pathogens

Nasal vaccination has been shown to provide optimal protection against respiratory pathogens. However, mucosal vaccination requires the implementation of specific immunization strategies to improve its effectiveness. Nanotechnology appears a key approach to improve the effectiveness of mucosal vaccines, since several nanomaterials provide mucoadhesion, enhance mucosal permeability, control antigen release and possess adjuvant properties. Mycoplasma hyopneumoniae is the main causative agent of enzootic pneumonia in pigs, a respiratory disease responsible for considerable economic losses in the pig farming worldwide. The present work developed, characterized, and tested in vivo an innovative dry powder nasal vaccine, obtained from the deposition on a solid carrier of an inactivated antigen and a chitosan-coated nanoemulsion, as an adjuvant. The nanoemulsion was obtained through a low-energy emulsification technique, a method that allowed to achieve nano droplets in the order of 200 nm. The oil phase selected was alpha-tocopherol, sunflower oil, and poly(ethylene glycol) hydroxystearate used as non-ionic tensioactive. The aqueous phase contained chitosan, which provides a positive charge to the emulsion, conferring mucoadhesive properties and favoring interactions with inactivated M. hyopneumoniae. Finally, the nanoemulsion was layered with a mild and scalable process onto a suitable solid carrier (i.e., lactose, mannitol, or calcium carbonate) to be transformed into a solid dosage form for administration as dry powder. In the experimental study, the nasal vaccine formulation with calcium carbonate was administered to piglets and compared to intramuscular administration of a commercial vaccine and of the dry powder without antigen, aimed at evaluating the ability of IN vaccination to elicit an in vivo local immune response and a systemic immune response. Intranasal vaccination was characterized by a significantly higher immune response in the nasal mucosa at 7 days post-vaccination, elicited comparable levels of Mycoplasma-specific IFN-γ secreting cells and comparable, if not higher, responsiveness of B cells expressing IgA and IgG in peripheral blood mononuclear cells, with those detected upon a conventional intramuscular immunization. In conclusion, this study illustrates a simple and effective strategy for the development of a dry powder vaccine formulation for nasal administration which could be used as alternative to current parenteral commercial vaccines.

Development of multistage recombinant protein vaccine formulations against toxoplasmosis using a new chitosan and porin based adjuvant system

Toxoplasmosis is a global health problem affecting both human and animal populations. The lack of effective treatment makes the development of a vaccine against toxoplasmosis one of the main goals in the management of this disease. In our study, vaccine formulations containing the multistage recombinant antigens, rBAG1 + rGRA1 were developed with a combined adjuvant system consisting of chitosan and Salmonella Typhi porins in micro (MicroAS) and nanoparticulate (NanoAS) forms. BALB/c mice were immunized intraperitoneally with vaccine formulations two times at three-week intervals. Three weeks after the second vaccination, mice were challenged with 7-8 live tissue cysts of the virulent T. gondii PRU strain by oral gavage. Higher cellular uptake by macrophages and enhanced cellular (IFN-γ and I-4 in stimulated spleen cells) and humoral (IgG, IgG1, IgG2a) responses were obtained with the adjuvanted formulation, higher with microsystem when compared to that of nanosystem. Microsystem was found to stimulate Th1-polarized immune responses, whereasnon-adjuvanted antigens stimulated Th2-polarized immune response. The highest survival rate and reduction in cysts numbers and T. gondii DNA were obtained with the adjuvanted antigens.Our study showed that adjuvanted multistage recombinant vaccine systems increase theimmune response with strong protection againstT. gondii, more profoundly in microparticulate form.

The Designing of a Gel Formulation with Chitosan Polymer Using Liposomes as Nanocarriers of Amphotericin B for a Non-invasive Treatment Model of Cutaneous Leishmaniasis

PURPOSE

Leishmaniasis is a disease caused by different Leishmania spp., which are transmitted to humans by a bite of infected female sand flies. Cutaneous leishmaniasis (CL, oriental sore), visceral leishmaniasis (VL), and mucocutaneous leishmaniasis (MCL) are three main clinical forms, however, only CL and VL are seen in Turkey. Cutaneous leishmaniasis is characterized by skin lesion(s) and is one of the most important vector-borne diseases in Turkey with over 2000 cases reported annually in 40 out of 81 provinces. The treatment is usually made invasively and painfully by intralesional injection of pentavalent antimony compounds. Non-invasive and innovative treatment methods are needed as aimed in this study.

METHODS

In the present study, one of the classical antileishmanial drugs, amphotericin B (AmB), encapsulated in liposomes was evaluated using non-invasive design based on chitosan, which is a nontoxic, biocompatible and biodegradable polymer. To avoid the invasive effect of conventional intralesional needle application, the drug was encapsulated in liposomes and incorporated into a chitosan gel for applying topically on the skin lesion. The efficacy of encapsulation of amphotericin B into liposomes and the drug release from liposomes were studied. The chitosan gel was evaluated for viscosity, flowability, appearance and pH. The efficacy of the drug embedded into chitosan gel, liposomal AmB alone and chitosan gel alone in four different concentrations was also tested using Leishmania spp. promastigotes in vitro.

RESULTS

The findings have shown that AmB was encapsulated into the liposomes with high efficiency (86.6%) and long-term physical and chemical stability. Therefore, designed liposomal formulation was suitable for sustained release. The appearance of the drug-embedded chitosan gel was transparent and appropriate. Chitosan gels showed non- Newtonian behavior and plastic flow. The liposomal AmB also showed higher efficacy with no parasites in all concentrations while drug embedded into chitosan gel and chitosan gel alone were effective in two higher concentrations. The lower efficacy of the drug-embedded chitosan gel in 24 h in in-vitro study was probably due to slow release of the drug.

CONCLUSION

The gel design created in this study will provide ease of use for the lesions of CL patients that do not have a specific number, size, and shape. Follow-up studies by the ex-vivo macrophage infection model with Leishmania intracellular amastigote forms and Leishmania-infected animal models are needed to understand the present design's efficacy better.

Applications of Chitosan-Alginate-Based Nanoparticles-An Up-to-Date Review

Chitosan and alginate are two of the most studied natural polymers that have attracted interest for multiple uses in their nano form. The biomedical field is one of the domains benefiting the most from the development of nanotechnology, as increasing research interest has been oriented to developing chitosan-alginate biocompatible delivery vehicles, antimicrobial agents, and vaccine adjuvants. Moreover, these nanomaterials of natural origin have also become appealing for environmental protection (e.g., water treatment, environmental-friendly fertilizers, herbicides, and pesticides) and the food industry. In this respect, the present paper aims to discuss some of the newest applications of chitosan-alginate-based nanomaterials and serve as an inception point for further research in the field.

Nanovaccine: an emerging strategy

INTRODUCTION

Vaccination is so far the most effective way of eradicating infections. Rapidly emerging drug resistance against infectious diseases and chemotherapy-related toxicities in cancer warrant immediate vaccine development to save mankind. Subunit vaccines alone, however, fail to elicit sufficiently strong and long-lasting protective immunity against deadly pathogens. Nanoparticle (NP)-based delivery vehicles like microemulsions, liposomes, virosomes, nanogels, micelles and dendrimers offer promising strategies to overcome limitations of traditional vaccine adjuvants. Nanovaccines can improve targeted delivery, antigen presentation, stimulation of body's innate immunity, strong T cell response combined with safety to combat infectious diseases and cancers. Further, nanovaccines can be highly beneficial to generate effective immutherapeutic formulations against cancer.

AREAS COVERED

This review summarizes the emerging nanoparticle strategies highlighting their success and challenges in preclinical and clinical trials in infectious diseases and cancer. It provides a concise overview of current nanoparticle-based vaccines, their adjuvant potential and their cellular delivery mechanisms.

EXPERT OPINION

The nanovaccines (50-250 nm in size) are most efficient in terms of tissue targeting, prolonged circulation and preferential uptake by the professional APCs chiefly due to their small size. More rational designing, improved antigen loading, extensive functionalization and targeted delivery are some of the future goals of ideal nanovaccines.

USE OF ARTIFICIAL CELLS AS DRUG CARRIERS

Cells are the fundamental functional units of biological systems and mimicking their size, function and complexity is a primary goal in the development of new therapeutic strategies. Recent advances in chemistry, synthetic biology and material science have enabled the development of cell membrane-based drug delivery systems (DDSs), often referred to as "artificial cells" or protocells. Artificial cells can be made by removing functions from natural systems in a top-down manner, or assembly from synthetic, organic or inorganic materials, through a bottom-up approach where simple units are integrated to form more complex structures. This review covers the latest advances in the development of artificial cells as DDSs, highlighting how their designs have been inspired by natural cells or cell membranes. Advancement of artificial cell technologies has led to a set of drug carriers with effective and controlled release of a variety of therapeutics for a range of diseases, and with increasing complexity they will have a greater impact on therapeutic designs.

Exploring novel and potent cell penetrating peptides in the proteome of SARS-COV-2 using bioinformatics approaches

Among various delivery systems for vaccine and drug delivery, cell-penetrating peptides (CPPs) have been known as a potent delivery system because of their capability to penetrate cell membranes and deliver some types of cargoes into cells. Several CPPs were found in the proteome of viruses such as Tat originated from human immunodeficiency virus-1 (HIV-1), and VP22 derived from herpes simplex virus-1 (HSV-1). In the current study, a wide-range of CPPs was identified in the proteome of SARS-CoV-2, a new member of coronaviruses family, using in silico analyses. These CPPs may play a main role for high penetration of virus into cells and infection of host. At first, we submitted the proteome of SARS-CoV-2 to CellPPD web server that resulted in a huge number of CPPs with ten residues in length. Afterward, we submitted the predicted CPPs to C2Pred web server for evaluation of the probability of each peptide. Then, the uptake efficiency of each peptide was investigated using CPPred-RF and MLCPP web servers. Next, the physicochemical properties of the predicted CPPs including net charge, theoretical isoelectric point (pI), amphipathicity, molecular weight, and water solubility were calculated using protparam and pepcalc tools. In addition, the probability of membrane binding potential and cellular localization of each CPP were estimated by Boman index using APD3 web server, D factor, and TMHMM web server. On the other hand, the immunogenicity, toxicity, allergenicity, hemolytic potency, and half-life of CPPs were predicted using various web servers. Finally, the tertiary structure and the helical wheel projection of some CPPs were predicted by PEP-FOLD3 and Heliquest web servers, respectively. These CPPs were divided into: a) CPP containing tumor homing motif (RGD) and/or tumor penetrating motif (RXXR); b) CPP with the highest Boman index; c) CPP with high half-life (~100 hour) in mammalian cells, and d) CPP with +5.00 net charge. Based on the results, we found a large number of novel CPPs with various features. Some of these CPPs possess tumor-specific motifs which can be evaluated in cancer therapy. Furthermore, the novel and potent CPPs derived from SARS-CoV-2 may be used alone or conjugated to some sequences such as nuclear localization sequence (NLS) for vaccine and drug delivery.

How glycobiology can help us treat and beat the COVID-19 pandemic

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged during the last months of 2019, spreading throughout the world as a highly transmissible infectious illness designated as COVID-19. Vaccines have now appeared, but the challenges in producing sufficient material and distributing them around the world means that effective treatments to limit infection and improve recovery are still urgently needed. This review focuses on the relevance of different glycobiological molecules that could potentially serve as or inspire therapeutic tools during SARS-CoV-2 infection. As such, we highlight the glycobiology of the SARS-CoV-2 infection process, where glycans on viral proteins and on host glycosaminoglycans have critical roles in efficient infection. We also take notice of the glycan-binding proteins involved in the infective capacity of virus and in human defense. In addition, we critically evaluate the glycobiological contribution of candidate drugs for COVID-19 therapy such as glycans for vaccines, anti-glycan antibodies, recombinant lectins, lectin inhibitors, glycosidase inhibitors, polysaccharides, and numerous glycosides, emphasizing some opportunities to repurpose FDA-approved drugs. For the next-generation drugs suggested here, biotechnological engineering of new probes to block the SARS-CoV-2 infection might be based on the essential glycobiological insight on glycosyltransferases, glycans, glycan-binding proteins, and glycosidases related to this pathology.