Liposome-based vaccines

Advancements in Nanoparticle-Based Adjuvants for Enhanced Tuberculosis Vaccination: A Review

Tuberculosis (TB) remains a leading cause of morbidity and mortality worldwide, necessitating the development of more effective vaccines. Nanoparticle-based adjuvants represent a promising approach to enhancing tuberculosis vaccine efficacy. This review focuses on the advantages of nanoparticulate-loaded vaccines, emphasizing their ability to improve antigen delivery, safety, and immunogenicity. We discuss the various types of nanoparticles and their unique physicochemical properties that contribute to improved antigen delivery and sustained immune activation. Additionally, we highlight the advantages of nanoparticle-based adjuvants in inducing strong cellular and humoral immunity, enhancing vaccine stability, and reducing adverse effects. Finally, we address current challenges and future perspectives in the application of these novel adjuvants, emphasizing their potential to transform TB vaccine strategies and ultimately contribute to better global health outcomes.

Nanotechnology's frontier in combatting infectious and inflammatory diseases: prevention and treatment

Inflammation-associated diseases encompass a range of infectious diseases and non-infectious inflammatory diseases, which continuously pose one of the most serious threats to human health, attributed to factors such as the emergence of new pathogens, increasing drug resistance, changes in living environments and lifestyles, and the aging population. Despite rapid advancements in mechanistic research and drug development for these diseases, current treatments often have limited efficacy and notable side effects, necessitating the development of more effective and targeted anti-inflammatory therapies. In recent years, the rapid development of nanotechnology has provided crucial technological support for the prevention, treatment, and detection of inflammation-associated diseases. Various types of nanoparticles (NPs) play significant roles, serving as vaccine vehicles to enhance immunogenicity and as drug carriers to improve targeting and bioavailability. NPs can also directly combat pathogens and inflammation. In addition, nanotechnology has facilitated the development of biosensors for pathogen detection and imaging techniques for inflammatory diseases. This review categorizes and characterizes different types of NPs, summarizes their applications in the prevention, treatment, and detection of infectious and inflammatory diseases. It also discusses the challenges associated with clinical translation in this field and explores the latest developments and prospects. In conclusion, nanotechnology opens up new possibilities for the comprehensive management of infectious and inflammatory diseases.

Nanomaterials in tuberculosis DNA vaccine delivery: historical perspective and current landscape

Vaccinations, especially DNA vaccines that promote host immunity, are the most effective interventions for tuberculosis (TB) control. However, the vaccine delivery system exhibits a significant impact on the protective effects of the vaccine. Recently, effective nanomaterial-based delivery systems (including nanoparticles, nanogold, nanoliposomes, virus-like particles, and virus carriers) have been developed for DNA vaccines to control TB. This review highlights the historical development of various nanomaterial-based delivery systems for TB DNA vaccines, along with the emerging technologies. Nanomaterial-based vaccine delivery systems could enhance the efficacy of TB vaccination; therefore, this summary could guide nanomaterial selection for optimal and safe vaccine delivery, facilitating the design and development of highly effective TB vaccines.

Vaccines for colorectal cancer: an update

Colorectal cancer (CRC) is known as the third most common and fourth leading cancer associated death worldwide. The occurrence of metastasis has remained as a critical challenge in CRC, so that distant metastasis (mostly to the liver) has been manifested in about 20%-25% of patients. Several screening approaches have introduced for detecting CRC in different stages particularly in early stages. The standard treatments for CRC are surgery, chemotherapy and radiotherapy, in alone or combination. Immunotherapy is a set of novel approaches with the aim of remodeling the immune system battle with metastatic cancer cells, such as immunomodulatory monoclonal antibodies (immune checkpoint inhibitors), adoptive cell transfer (ACT) and cancer vaccine. Cancer vaccines are designed to trigger the intense response of immune system to tumor-specific antigens. In two last decades, introduction of new cancer vaccines and designing several clinical trials with vaccine therapy, have been taken into consideration in colon cancer patients. This review will describe the treatment approaches with the special attention to vaccines applied to treat colorectal cancer.

Potential Hepatitis B Vaccine Formulation Prepared by Uniform-Sized Lipid Hybrid PLA Microparticles with Adsorbed Hepatitis B Surface Antigen

For the purpose of strengthening the immunogenicity of the hepatitis B vaccine, which contains hepatitis B surface antigen (HBsAg), the development of biodegradable poly(lactic acid) (PLA) microparticles (MPs) modified with the cationic surfactant didodecyldimethylammonium bromide (DDAB) was attempted. DDAB-PLA MPs with an uniform size of about 1 μm were prepared in a simple and mild way. DDAB-PLA MPs with increased surface charge enhanced antigen adsorption capacity compared to plain PLA MPs. After immunization, DDAB-PLA MPs induced the gene expression of inflammatory cytokines and chemokines, which facilitated the following immune responses. DDAB-PLA MPs augmented the expression of co-stimulatory molecules along with the activation of bone-marrow-derived dendritic cells (BMDCs). DDAB-PLA MP-based vaccine formulations efficiently induced antibody production more than the aluminum-based vaccine and plain PLA MP-based formulation in vivo. Moreover, DDAB-PLA MPs were more likely to generate the polarization of the Th1 response indicating the cytotoxic ability against infectious pathogens. In conclusion, DDAB-PLA MPs could be a potent vaccine formulation to prime robust cellular and humoral immune responses.

The Five Immune Forces Impacting DNA-Based Cancer Immunotherapeutic Strategy

DNA-based vaccine strategy is increasingly realized as a viable cancer treatment approach. Strategies to enhance immunogenicity utilizing tumor associated antigens have been investigated in several pre-clinical and clinical studies. The promising outcomes of these studies have suggested that DNA-based vaccines induce potent T-cell effector responses and at the same time cause only minimal side-effects to cancer patients. However, the immune evasive tumor microenvironment is still an important hindrance to a long-term vaccine success. Several options are currently under various stages of study to overcome immune inhibitory effect in tumor microenvironment. Some of these approaches include, but are not limited to, identification of neoantigens, mutanome studies, designing fusion plasmids, vaccine adjuvant modifications, and co-treatment with immune-checkpoint inhibitors. In this review, we follow a Porter’s analysis analogy, otherwise commonly used in business models, to analyze various immune-forces that determine the potential success and sustainable positive outcomes following DNA vaccination using non-viral tumor associated antigens in treatment against cancer.

Delivery methods to increase cellular uptake and immunogenicity of DNA vaccines

DNA vaccines are ideal candidates for global vaccination purposes because they are inexpensive and easy to manufacture on a large scale such that even people living in low-income countries can benefit from vaccination. However, the potential of DNA vaccines has not been realized owing mainly to the poor cellular uptake of DNA in vivo resulting in the poor immunogenicity of DNA vaccines. In this review, we discuss the benefits and shortcomings of several promising and innovative non-biological methods of DNA delivery that can be used to increase cellular delivery and efficacy of DNA vaccines.

Quantitative evaluation of DNA dissociation from liposome carriers and DNA escape from endosomes during lipid-mediated gene delivery

Nonviral vectors are highly attractive for gene therapy from a clinical point of view, and cationic lipid nanoparticles in particular have generated considerable interest. However, despite considerable recent advances, problems associated with low transfection efficiencies remain to be resolved to fully meet the potential of these vectors. The trafficking of plasmid DNA (pDNA) from the extracellular space up to the nucleus is prevented by several barriers, including liposome/pDNA dissociation within the endosome and pDNA escape into the cytosol. The aim of this work was to develop and optimize a tool that could offer simultaneous quantitative information both on the intracellular dissociation of oligonucleotides from lipid nanoparticles, and on the DNA escape from endocytic compartments. The ability to follow in real time both of these processes simultaneously (in a quantitative manner) is expected to be of high value in the rationalization and conception of new lipid nanoparticle vectors for gene delivery for therapeutic purposes. To this effect, a combination of Förster resonance energy transfer (FRET) and colocalization microscopy was employed. We show that it is possible to distinguish between liposome/pDNA dissociation and depletion of DNA within endosomes, providing resolution for the detection of intermediate species between endocytic particles with intact lipoplexes and endosomes devoid of DNA because of DNA escape or degradation. We demonstrate that after endocytosis, exceptionally few endocytic particles are found to exhibit simultaneously DNA/lipid colocalization and low FRET (DNA/lipid dissociation). These results clearly point to an extremely short-lived state for free plasmid within endosomes, which either escapes at once to the cytosol or is degraded within the endocytic compartment (because of exposure of DNA). It is possible that this limitation greatly contributes to reduction in probability of successful gene delivery through cationic lipid particles.

Modular Three-component Delivery System Facilitates HLA Class I Antigen Presentation and CD8(+) T-cell Activation Against Tumors

Cell-mediated immunotherapies have potential as stand-alone and adjuvant therapies for cancer. However, most current protocols suffer from one or more of three major issues: cost, safety, or efficacy. Here we present a nanoparticle delivery system that facilitates presentation of an immunogenic measles antigen specifically in cancer cells. The delivery system does not contain viral particles, toxins, or biologically derived material. Treatment with this system facilitates activation of a secondary immune response against cancer cells, bypassing the need to identify tumor-associated antigens or educate the immune system through a primary immune response. The delivery system consists of a stealth liposome displaying a cancer-specific targeting peptide, named H1299.3, on its exterior surface and encapsulating H250, an immunogenic human leukocyte antigen class 1 restricted peptide. This targeted-nanoparticle facilitates presentation of the H250 peptide in major histocompatibility complex class I molecules. Activation is dependent on the targeting peptide, previous antigen exposure, and utilizes a novel autophagy-mediated mechanism to facilitate presentation. Treatment with this liposome results in a significant reduction of tumor growth using an aggressive LLC1 model in vaccinated C57BL/6 mice. These data provide proof-of-principle for a novel cell-mediated immunotherapy that is scalable, contains no biologically derived material, and is an efficacious cancer therapy.

Phase separation behavior of mixed lipid systems at neutral and low pH: coarse-grained simulations with DMD/LIME

We extend LIME, an intermediate resolution, implicit solvent model for phospholipids previously used in discontinuous molecular dynamics simulations of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayer formation at 325 K, to the description of the geometry and energetics of 1,2-distearoyl-sn-glycero-3-phospho-L-serine (DSPS) and 1,2-dihenarachidoyl-sn-glycero-3-phosphocholine (21PC) and mixtures thereof at both neutral and low pH at 310 K. A multiscale modeling approach is used to calculate the LIME parameters from atomistic simulation data on a mixed DPPC/DSPS system at different pH values. In the model, 17 coarse-grained sites represent DSPS and 18 coarse-grained sites represent 21PC. Each of these coarse-grained sites is classified as 1 of 9 types. LIME/DMD simulations of equimolar bilayers show the following: (1) 21PC/DSPS bilayers with and without surface area restrictions separate faster at low pH than at neutral pH, (2) 21PC/DSPS systems separate at approximately the same rate regardless of whether they are subjected to surface area restrictions, and (3) bilayers with a molar ratio of 9:1 (21PC:DSPS) phase separate to form heterogeneous domains faster at low pH than at neutral pH. Our results are consistent with experimental findings of Sofou and co-workers (Bandekar et al. Mol. Pharmaceutics, 2013, 10, 152-160; Karve et al. Biomaterials, 2010, 31, 4409-4416) that more doxorubicin is released from 21PC/DSPS liposomes at low pH than at neutral pH, presumably because greater phase separation is achieved at low pH than at neutral pH. These are the first molecular-level simulations of the phase separation in mixed lipid bilayers induced by a change in pH.

Liposomes as vaccine delivery systems: a review of the recent advances

Liposomes and liposome-derived nanovesicles such as archaeosomes and virosomes have become important carrier systems in vaccine development and the interest for liposome-based vaccines has markedly increased. A key advantage of liposomes, archaeosomes and virosomes in general, and liposome-based vaccine delivery systems in particular, is their versatility and plasticity. Liposome composition and preparation can be chosen to achieve desired features such as selection of lipid, charge, size, size distribution, entrapment and location of antigens or adjuvants. Depending on the chemical properties, water-soluble antigens (proteins, peptides, nucleic acids, carbohydrates, haptens) are entrapped within the aqueous inner space of liposomes, whereas lipophilic compounds (lipopeptides, antigens, adjuvants, linker molecules) are intercalated into the lipid bilayer and antigens or adjuvants can be attached to the liposome surface either by adsorption or stable chemical linking. Coformulations containing different types of antigens or adjuvants can be combined with the parameters mentioned to tailor liposomal vaccines for individual applications. Special emphasis is given in this review to cationic adjuvant liposome vaccine formulations. Examples of vaccines made with CAF01, an adjuvant composed of the synthetic immune-stimulating mycobacterial cordfactor glycolipid trehalose dibehenate as immunomodulator and the cationic membrane forming molecule dimethyl dioctadecylammonium are presented. Other vaccines such as cationic liposome-DNA complexes (CLDCs) and other adjuvants like muramyl dipeptide, monophosphoryl lipid A and listeriolysin O are mentioned as well. The field of liposomes and liposome-based vaccines is vast. Therefore, this review concentrates on recent and relevant studies emphasizing current reports dealing with the most studied antigens and adjuvants, and pertinent examples of vaccines. Studies on liposome-based veterinary vaccines and experimental therapeutic cancer vaccines are also summarized.

Recent progress in adjuvant discovery for peptide-based subunit vaccines

Peptide-based subunit vaccines are of great interest in modern immunotherapy as they are safe, easy to produce and well defined. However, peptide antigens produce a relatively weak immune response, and thus require the use of immunostimulants (adjuvants) for optimal efficacy. Developing a safe and effective adjuvant remains a challenge for peptide-based vaccine design. Recent advances in immunology have allowed researchers to have a better understanding of the immunological implication of related diseases, which facilitates more rational design of adjuvant systems. Understanding the molecular structure of the adjuvants allows the establishment of their structure-activity relationships which is useful for the development of next-generation adjuvants. This review summarizes the current state of adjuvants development in the field of synthetic peptide-based vaccines. The structural, chemical and biological properties of adjuvants associated with their immunomodulatory effects are discussed.

Distribution characteristics of DNA vaccine encoded with glycoprotein C from Anatid herpesvirus 1 with chitosan and liposome as deliver carrier in ducks

Background

A eukaryotic expression plasmid encoding glycoprotein C (gC) of Anatid herpesvirus 1 (AnHV-1) (pcDNA3.1-gC) was constructed and validated. The tissue distribution of chitosan/DNA complexes, liposome/DNA complexes and pcDNA3.1-gC alone were evaluated using a quantitative real-time PCR based TaqMan™ probe following intramuscular administration in ducklings.

Results

Compared with pcDNA3.1-gC alone, liposomes universally increased the plasmid DNA copy number at the injection sites, liver, spleen, heart, brain, bursa of Fabricius, and especially in the enteron (esophagus, duodenum, rectum, and cecum). Chitosan also universally increased the plasmid DNA copy number at the injection sites, liver, spleen, heart, brain and esophagus. Compared with lipoplex-gC, higher chitosan-gC plasmid DNA copy numbers were detected at the injection sites, liver, spleen, heart, brain and esophagus. In contrast, compared with lipoplex-gC, lower copy numbers of chitosan-gC plasmid DNA were detected in the duodenum, rectum and cecum.

Conclusions

The results of this study demonstrated that chitosan and liposomes mediated rapid and extensive plasmid distribution in duck tissues, with low levels maintained from 1 d after DNA vaccination.

Role of Macrophage in Tumor Microenvironment: Prospect in Cancer Immunotherapy

Current evidence suggests an increasing role of macrophages in inflammation and tumor progression. Most tumors contain an abundant number of macrophages as a major component of their leukocyte infiltrate, which co-exist with tumor cells at the tumor microenvironment. Upon activation with soluble tumor antigens, macrophages release a distinct repertoire of growth factor, cytokines, chemokines and enzymes that inhibit growth of the tumor. However, the anti-tumor immune response induced by macrophages does not always ensue. Tumor cells themselves are capable of down-regulating macrophage phenotype and functions and anti-tumor immune responses in the tumor-bearing host. The present review aims to elucidate the role of macrophages in tumor growth and progression, invasion, metastasis, and angiogenesis at the site of tumor growth. Moreover, the effect of tumor microenvironment on the phenotype and function of macrophages, which are altered due to the continuous exposure of various soluble and non-soluble tumor promoting factors secreted by tumor cells, and implication of macrophages in cancer immunotherapy have been discussed in detail.

Peptide Vaccine Therapy in Colorectal Cancer

Colorectal cancer is the third most common cause of cancer-related deaths and the second most prevalent (after breast cancer) in the western world. High metastatic relapse rates and severe side effects associated with the adjuvant treatment have urged oncologists and clinicians to find a novel, less toxic therapeutic strategy. Considering the limited success of the past clinical trials involving peptide vaccine therapy to treat colorectal cancer, it is necessary to revise our knowledge of the immune system and its potential use in tackling cancer. This review presents the efforts of the scientific community in the development of peptide vaccine therapy for colorectal cancer. We review recent clinical trials and the strategies for immunologic monitoring of responses to peptide vaccine therapy. We also discuss the mechanisms underlying the therapy and potential molecular targets in colon cancer.

Intradermal naked plasmid DNA immunization: mechanisms of action

Plasmid DNA is a promising vaccine modality that is regularly examined in prime-boost immunization regimens. Recent advances in skin immunity increased our understanding of the sophisticated cutaneous immune network, which revived scientific interest in delivering vaccines to the skin. Intradermal administration of plasmid DNA via needle injection is a simple and inexpensive procedure that exposes the plasmid and its encoded antigen to the dermal immune surveillance system. This triggers unique mechanisms for eliciting local and systemic immunity that can confer protection against pathogens and tumors. Understanding the mechanisms of intradermal plasmid DNA immunization is essential for enhancing and modulating its immunogenicity. With regard to vaccination, this is of greater importance as this routine injection technique is highly desirable for worldwide immunization. This article will focus on the current understanding of the mechanisms involved in antigen expression and presentation during primary and secondary syringe and needle intradermal plasmid DNA immunization.

Technologies for enhanced efficacy of DNA vaccines

Despite many years of research, human DNA vaccines have yet to fulfill their early promise. Over the past 15 years, multiple generations of DNA vaccines have been developed and tested in preclinical models for prophylactic and therapeutic applications in the areas of infectious disease and cancer, but have failed in the clinic. Thus, while DNA vaccines have achieved successful licensure for veterinary applications, their poor immunogenicity in humans when compared with traditional protein-based vaccines has hindered their progress. Many strategies have been attempted to improve DNA vaccine potency including use of more efficient promoters and codon optimization, addition of traditional or genetic adjuvants, electroporation, intradermal delivery and various prime-boost strategies. This review summarizes these advances in DNA vaccine technologies and attempts to answer the question of when DNA vaccines might eventually be licensed for human use.

DNA vaccination: using the patient's immune system to overcome cancer

Cancer is one of the most challenging diseases of today. Optimization of standard treatment protocols consisting of the main columns of chemo- and radiotherapy followed or preceded by surgical intervention is often limited by toxic side effects and induction of concomitant malignancies and/or development of resistant mechanisms. This requires the development of therapeutic strategies which are as effective as standard therapies but permit the patients a life without severe negative side effects. Along this line, the development of immunotherapy in general and the innovative concept of DNA vaccination in particular may provide a venue to achieve this goal. Using the patient's own immune system by activation of humoral and cellular immune responses to target the cancer cells has shown first promising results in clinical trials and may allow reduced toxicity standard therapy regimen in the future. The main challenge of this concept is to transfer the plethora of convincing preclinical and early clinical results to an effective treatment of patients.