Preparation and Characterization of Innovative Protein-coated Poly(Methylmethacrylate) Core-shell Nanoparticles for Vaccine Purposes

A Nanoplasmonic Assay for Point-of-Care Detection of Mannose-Binding Lectin in Human Serum

Mannose-binding lectin (MBL) activates the complement system lectin pathway and subsequent inflammatory mechanisms. The incidence and outcome of many human diseases, such as brain ischemia and infections, are associated with and influenced by the activity and serum concentrations of MBL in body fluids. To quantify MBL levels, tests based on ELISA are used, requiring several incubation and washing steps and lengthy turnaround times. Here, we aimed to develop a nanoplasmonic assay for direct MBL detection in human serum at the point of care. Our assay is based on gold nanorods (GNRs) functionalized with mannose (Man-GNRs) via an amphiphilic linker. We experimentally determined the effective amount of sugar linked to the nanorods' surface, resulting in an approximate grafting density of 4 molecules per nm2, and an average number of 11 to 13 MBL molecules binding to a single nanoparticle. The optimal Man-GNRs concentration to achieve the highest sensitivity in MBL detection was 15 μg·mL-1. The specificity of the assay for MBL detection both in simple buffer and in complex pooled human sera was confirmed. Our label-free biosensor is able to detect MBL concentrations as low as 160 ng·mL-1 within 15 min directly in human serum via a one-step reaction and by using a microplate reader. Hence, it forms the basis for a fast, noninvasive, point-of-care assay for diagnostic indications and monitoring of disease and therapy.

A Systematic Overview of Eudragit® Based Copolymer for Smart Healthcare

Eudragit, synthesized by radical polymerization, is used for enteric coating, precise temporal release, and targeting the entire gastrointestinal system. Evonik Healthcare Germany offers different grades of Eudragit. The ratio of methacrylic acid to its methacrylate-based monomers used in the polymerization reaction defines the final product's characteristics and consequently its potential range of applications. Since 1953, these polymers have been made to use in a wide range of healthcare applications around the world. In this review, we reviewed the "known of knowns and known of unknowns" about Eudragit, from molecule to material design, its characterization, and its applications in healthcare.

Developments in Vaccine Adjuvants

Vaccines, including subunit, recombinant, and conjugate vaccines, require the use of an immunostimulator/adjuvant for maximum efficacy. Adjuvants not only enhance the strength and longevity of immune responses but may also influence the type of response. In this chapter, we review the adjuvants that are available for use in human vaccines, such as alum, MF59, AS03, and AS01. We extensively discuss their composition, characteristics, mechanism of action, and effects on the immune system. Additionally, we summarize recent trends in adjuvant discovery, providing a brief overview of saponins, TLRs agonists, polysaccharides, nanoparticles, cytokines, and mucosal adjuvants.

Determination of conjugated protein on nanoparticles by an adaptation of the Coomassie blue dye method

A new accurate spectrophotometric method for protein determination on nanoparticles is described. The method is based on the Coomassie blue dye that binds to the basic and aromatic amino acid residues of proteins, especially arginine and lysine. A known amount of reagent dye was mixed with a variety of protein-loaded nanoparticles. Thereafter the unconjugated reagent was mixed with excess protein (bovine serum albumin) and titrated. In this method, the reacted dye on the protein coating of nanoparticle is directly determined, in opposite to the conventional method, in which the conjugated protein is determined as the difference between the non-conjugated protein found in the supernatant after centrifugation, and the total amount of protein originally used. This method is able to measure amounts of coated protein lower than 1 ppm.

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Simple and accurate method especially adapted for protein-coated nanoparticles.

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The amino acid residues of protein in the nanoparticle surface react with Coomassie brilliant blue dye.

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The unreacted dye is titrated with an excess of a standard protein.

Induction of Immune Responses by DNA Vaccines Formulated with Dendrimer and Poly (Methyl Methacrylate) (PMMA) Nano-Adjuvants in BALB/c Mice Infected with Leishmania major

BACKGROUND:

Leishmaniasis is a parasitic disease induced by a protozoan from the genus Leishmania. No effective vaccine has yet been developed against the disease.

AIM:

In this work, two nano-vaccines, TSA recombinant plasmid and dendrimer and poly (methyl methacrylate) (PMMA) nanoparticles (as adjuvants), were designed and tested for their immunogenicity in BALB/c mice.

METHODS:

After the plasmid construction and preparation of adjuvants, three intramuscular injections of the nano-vaccines (100 µg) and the recombinant TSA protein (20 µg) were subcutaneously performed. Eventually, the challenged animals were infected with the parasites (1*10⁶ promastigotes). After the last injections of the nano-vaccines, the responses of their antibody subclasses and cytokines were assessed via ELISA method before and after the challenge.

RESULTS:

This study revealed that the new nano-vaccines were strong and effective in inducing specific antibody and cellular responses and reducing the parasite burden in the spleen compared to the control groups of Leishmania major-infected BALB/c mice.

CONCLUSION:

Based on the results, we can suggest that the formulated vaccines are suitable candidates for further studies in the field of leishmaniasis control.

Antimicrobial peptides: Possible anti-infective agents

Multidrug-resistant bacterial, fungal, viral, and parasitic infections are major health threats. The Infectious Diseases Society of America has expressed concern on the decrease of pharmaceutical companies working on antibiotic research and development. However, small companies, along with academic research institutes, are stepping forward to develop novel therapeutic methods to overcome the present healthcare situation. Among the leading alternatives to current drugs are antimicrobial peptides (AMPs), which are abundantly distributed in nature. AMPs exhibit broad-spectrum activity against a wide variety of bacteria, fungi, viruses, and parasites, and even cancerous cells. They also show potential immunomodulatory properties, and are highly responsive to infectious agents and innate immuno-stimulatory molecules. In recent years, many AMPs have undergone or are undergoing clinical development, and a few are commercially available for topical and other applications. In this review, we outline selected anion and cationic AMPs which are at various stages of development, from preliminary analysis to clinical drug development. Moreover, we also consider current production methods and delivery tools for AMPs, which must be improved for the effective use of these agents.

Biocompatible anionic polymeric microspheres as priming delivery system for effetive HIV/AIDS Tat-based vaccines

Here we describe a prime-boost regimen of vaccination in Macaca fascicularis that combines priming with novel anionic microspheres designed to deliver the biologically active HIV-1 Tat protein and boosting with Tat in Alum. This regimen of immunization modulated the IgG subclass profile and elicited a balanced Th1-Th2 type of humoral and cellular responses. Remarkably, following intravenous challenge with SHIV89.6P_cy243, vaccinees significantly blunted acute viremia, as compared to control monkeys, and this control was associated with significantly lower CD4⁺ T cell depletion rate during the acute phase of infection and higher ability to resume the CD4⁺ T cell counts in the post-acute and chronic phases of infection. The long lasting control of viremia was associated with the persistence of high titers anti-Tat antibodies whose profile clearly distinguished vaccinees in controllers and viremics. Controllers, as opposed to vaccinated and viremic cynos, exhibited significantly higher pre-challenge antibody responses to peptides spanning the glutamine-rich and the RGD-integrin-binding regions of Tat. Finally, among vaccinees, titers of anti-Tat IgG1, IgG3 and IgG4 subclasses had a significant association with control of viremia in the acute and post-acute phases of infection. Altogether these findings indicate that the Tat/H1D/Alum regimen of immunization holds promise for next generation vaccines with Tat protein or other proteins for which maintenance of the native conformation and activity are critical for optimal immunogenicity. Our results also provide novel information on the role of anti-Tat responses in the prevention of HIV pathogenesis and for the design of new vaccine candidates.

Immune responses in DNA vaccine formulated with PMMA following immunization and after challenge with Leishmania major

Leishmaniasis is a major infectious disease caused by protozoan parasites of the genus Leishmania. Despite of many efforts toward vaccine against Leishmania no effective vaccine has been approved yet. DNA vaccines can generate more powerful and broad immune responses than conventional vaccines. In order to increase immunity, the DNA vaccine has been supplemented with adjuvant. In this study a new nano-vaccine containing TSA recombinant plasmid and poly(methylmethacrylate) nanoparticles (act as adjuvant) was designed and its immunogenicity tested on BALB/c mouse. After three intramuscular injection of nano-vaccine (100 μg), the recombinant TSA protein (20 μg) was injected subcutaneously. Finally as a challenge animals were infected by Leishmania major. After the last injection of nano-vaccine, after protein booster injection, and also after challenge, cellular immune and antibody responses were evaluated by ELISA method. The findings of this study showed the new nano-vaccine was capable of induction both cytokines secretion and specific antibody responses, but predominant Th1 immune response characterized by IFN-γ production compared to control groups. Moreover, results revealed that nano-vaccine was effective in reducing parasite burden in the spleen of Leishmania major-infected BALB/c mice. Base on results, current candidate vaccine has potency for further studies.

Proper design of silica nanoparticles combines high brightness, lack of cytotoxicity and efficient cell endocytosis

Silica-based luminescent nanoparticles (SiNPs) show promising prospects in nanomedicine in light of their chemical properties and versatility. In this study, we have characterized silica core-PEG shell SiNPs derivatized with PEG moieties (NP-PEG), with external amino- (NP-PEG-amino) or carboxy-groups (NP-PEG-carbo), both in cell cultures as well as in animal models. By using different techniques, we could demonstrate that these SiNPs were safe and did not exhibit appreciable cytotoxicity in different relevant cell models, of normal or cancer cell types, growing either in suspension (JVM-2 leukemic cell line and primary normal peripheral blood mononuclear cells) or in adherence (human hepatocarcinoma Huh7 and umbilical vein endothelial cells). Moreover, by multiparametric flow cytometry, we could demonstrate that the highest efficiency of cell uptake and entry was observed with NP-PEG-amino, with a stable persistence of the fluorescence signal associated with SiNPs in the loaded cell populations both in vitro and in vivo settings suggesting this as an innovative method for cell traceability and detection in whole organisms. Finally, experiments performed with the endocytosis inhibitor Genistein clearly suggested the involvement of a caveolae-mediated pathway in SiNP endocytosis. Overall, these data support the safe use of these SiNPs for diagnostic and therapeutic applications.

A review of nanotechnological approaches for the prophylaxis of HIV/AIDS

Successful treatment and control of HIV/AIDS is one of the biggest challenges of 21st century. More than 33 million individuals are infected with HIV worldwide and more than 2 million new cases of HIV infection have been reported. The situation demands development of effective prevention strategies to control the pandemic of AIDS. Due to lack of availability of an effective HIV vaccine, antiretroviral drugs and nucleic acid therapeutics like siRNA have been explored for HIV prophylaxis. Clinical trials shave shown that antiretroviral drugs, tenofovir and emtricitabine can offer some degree of HIV prevention. However, complete prevention of HIV infection has not been achieved yet. Nanotechnology has brought a paradigm shift in the diagnosis, treatment and prevention of many diseases. The current review discusses potential of various nanocarriers such as dendrimers, polymeric nanoparticles, liposomes, lipid nanocarriers, drug nanocrystals, inorganic nanocarriers and nanofibers in improving efficacy of various modalities available for HIV prophylaxis.

Biocompatibility of engineered nanoparticles for drug delivery

The rapid advancement of nanotechnology has raised the possibility of using engineered nanoparticles that interact within biological environments for treatment of diseases. Nanoparticles interacting with cells and the extracellular environment can trigger a sequence of biological effects. These effects largely depend on the dynamic physicochemical characteristics of nanoparticles, which determine the biocompatibility and efficacy of the intended outcomes. Understanding the mechanisms behind these different outcomes will allow prediction of the relationship between nanostructures and their interactions with the biological milieu. At present, almost no standard biocompatibility evaluation criteria have been established, in particular for nanoparticles used in drug delivery systems. Therefore, an appropriate safety guideline of nanoparticles on human health with assessable endpoints is needed. In this review, we discuss the data existing in the literature regarding biocompatibility of nanoparticles for drug delivery applications. We also review the various types of nanoparticles used in drug delivery systems while addressing new challenges and research directions. Presenting the aforementioned information will aid in getting one step closer to formulating compatibility criteria for biological systems under exposure to different nanoparticles.

Protein-polymer hybrid nanoparticles for drug delivery

Amphiphilic bovine serum albumin-poly(methyl methacrylate) conjugate forms nanoparticles with the uniform size of ~100 nm by self-assembling. Loaded with the hydrophobic anti-tumor drug camptothecin, the nanoparticle efficiently delivers drugs into cancer cells, and thus inhibits ~79% of tumor growth in animals compared with free drug.

Recent advances in nanocarrier-based mucosal delivery of biomolecules

This review highlights the recent developments in the area of nanocarrier-based mucosal delivery of therapeutic biomolecules and antigens. Macromolecular drugs have the unique power to tackle challenging diseases but their structure, physicochemical properties, stability, pharmacodynamics, and pharmacokinetics place stringent demands on the way they are delivered into the body (e.g., inability to cross mucosal surfaces and biological membranes). Carrier-based drug delivery systems can diminish the toxicity of therapeutic biomolecules, improve their bioavailability and make possible their administration via less-invasive routes (e.g., oral, nasal, pulmonary, etc.). Thus, the development of functionalized nanocarriers and nanoparticle-based microcarriers for the delivery of macromolecular drugs is considered an important scientific challenge and at the same time a business breakthrough for the biopharmaceutical industry. In order to be translated to the clinic the nanocarriers need to be biocompatible, biodegradable, stable in biological media, non-toxic and non-immunogenic, to exhibit mucoadhesive properties, to cross mucosal barriers and to protect their sensitive payload and deliver it to its target site in a controlled manner, thus increasing significantly its bioavailability and efficacy.

Poly(methyl methacrylate) particulate carriers in drug delivery

Poly(methyl methacrylate) (PMMA) is one of the most widely explored biomedical materials because of its biocompatibility, and recent publications have shown an increasing interest in its applications as a drug carrier. PMMA-based particulate carriers (PMMA(P)) can be prepared either by polymerization methods or from pre-formed polymer-based techniques. Potential biomedical application of these particles includes their use as adjuvant for vaccines and carrier of many drugs as antibiotics and antioxidants via different routes of administration. Release of drugs from PMMA(P) occurs typically in a biphasic way with an incomplete drug release. To improve release profiles, recent strategies are focusing on increasing polymer hydrophilicity by synthesizing functionalized PMMA microspheres or by formulating PMMA composites with hydrophilic polymers. This review examines the current status of preparation techniques, drug release kinetics, biomedical applications and toxicity of these nano/micro PMMA-based particulate carriers.

Polímeros usados como sistemas de transporte de princípios ativos

Os diferentes sistemas de transporte têm evidenciado potencial terapêutico para uma grande variedade de princípios ativos, satisfazendo vários requisitos, como a prevenção da sua eliminação rápida do organismo, a redução da sua toxicidade sistêmica, a estabilização e a otimização do seu metabolismo, e o direcionamento específico ao local alvo e os mecanismos de defesa. No entanto, têm sido reconhecidos vários outros desafios associados à liberação específica do princípio ativo ao local alvo, pelo que, para ultrapassar os obstáculos químicos e biológicos, a seleção do polímero utilizado para a preparação do sistema de transporte é de importância crucial. O presente trabalho apresenta um relato sobre os principais polímeros naturais e sintéticos utilizados para a preparação de sistemas de transporte de princípios ativos in vivo.

Development of peptide and protein nanotherapeutics by nanoencapsulation and nanobioconjugation

The targeted delivery of therapeutic peptide by nanocarriers systems requires the knowledge of interactions of nanomaterials with the biological environment, peptide release, and stability of therapeutic peptides. Therapeutic application of nanoencapsulated peptides are increasing exponentially and >1000 peptides in nanoencapsulated form are in different clinical/trial phase. This review covers current scenario of therapeutic protein and peptides encapsulation on polymer to metallic nanocarriers including methods of protein encapsulation, peptide bioconjugation on nanoparticles, stability enhancement of encapsulated proteins and its biomedical applications.

Innovative approaches to develop prophylactic and therapeutic vaccines against HIV/AIDS

The acquired immunodeficiency syndrome (AIDS) emerged in the human population in the summer of 1981. According to the latest United Nations estimates, worldwide over 33 million people are infected with human immunodeficiency virus (HIV) and the prevalence rates continue to rise globally. To control the alarming spread of HIV, an urgent need exists for developing a safe and effective vaccine that prevents individuals from becoming infected or progressing to disease. To be effective, an HIV/AIDS vaccine should induce broad and long-lasting humoral and cellular immune responses, at both mucosal and systemic level. However, the nature of protective immune responses remains largely elusive and this represents one of the major roadblocks preventing the development of an effective vaccine. Here we summarize our present understanding of the factors responsible for resistance to infection or control of progression to disease in human and monkey that may be relevant to vaccine development and briefly review recent approaches which are currently being tested in clinical trials. Finally, the rationale and the current status of novel strategies based on nonstructural HIV-1 proteins, such as Tat, Nef and Rev, used alone or in combination with modified structural HIV-1 Env proteins are discussed.

Impact of viral dose and major histocompatibility complex class IB haplotype on viral outcome in mauritian cynomolgus monkeys vaccinated with Tat upon challenge with simian/human immunodeficiency virus SHIV89.6P

The effects of the challenge dose and major histocompatibility complex (MHC) class IB alleles were analyzed in 112 Mauritian cynomolgus monkeys vaccinated (n = 67) or not vaccinated (n = 45) with Tat and challenged with simian/human immunodeficiency virus (SHIV) 89.6P(cy243.) In the controls, the challenge dose (10 to 20 50% monkey infectious doses [MID(50)]) or MHC did not affect susceptibility to infection, peak viral load, or acute CD4 T-cell loss, whereas in the chronic phase of infection, the H1 haplotype correlated with a high viral load (P = 0.0280) and CD4 loss (P = 0.0343). Vaccination reduced the rate of infection acquisition at 10 MID(50) (P < 0.0001), and contained acute CD4 loss at 15 MID(50) (P = 0.0099). Haplotypes H2 and H6 were correlated with increased susceptibility (P = 0.0199) and resistance (P = 0.0087) to infection, respectively. Vaccination also contained CD4 depletion (P = 0.0391) during chronic infection, independently of the challenge dose or haplotype.

HIV-1 Tat-based vaccines: an overview and perspectives in the field of HIV/AIDS vaccine development

The HIV epidemic continues to represent one of the major problems worldwide, particularly in the Asia and Sub-Saharan regions of the world, with social and economical devastating effects. Although antiretroviral drugs have had a dramatically beneficial impact on HIV-infected individuals that have access to treatment, it has had a negligible impact on the global epidemic. Hence, the inexorable spreading of the HIV pandemic and the increasing deaths from AIDS, especially in developing countries, underscore the urgency for an effective vaccine against HIV/AIDS. However, the generation of such a vaccine has turned out to be extremely challenging. Here we provide an overview on the rationale for the use of non-structural HIV proteins, such as the Tat protein, alone or in combination with other HIV early and late structural HIV antigens, as novel, promising preventative and therapeutic HIV/AIDS vaccine strategies.

Induction of humoral and enhanced cellular immune responses by novel core-shell nanosphere- and microsphere-based vaccine formulations following systemic and mucosal administration

Anionic surfactant-free polymeric core-shell nanospheres and microspheres were previously described with an inner core constituted by poly(methylmethacrylate) (PMMA) and a highly hydrophilic outer shell composed of a hydrosoluble co-polymer (Eudragit L100-55). The outer shell is tightly linked to the core and bears carboxylic groups capable of adsorbing high amounts (antigen loading ability of up to 20%, w/w) of native basic proteins, mainly by electrostatic interactions, while preserving their activity. In the present study we have evaluated in mice the safety and immunogenicity of new vaccine formulations composed of these nano- and microspheres and the HIV-1 Tat protein. Vaccines were administered by different routes, including intramuscular, subcutaneous or intranasal and the results were compared to immunization with Tat alone or with Tat delivered with the alum adjuvant. The data demonstrate that the nano- and microspheres/Tat formulations are safe and induce robust and long-lasting cellular and humoral responses in mice after systemic and/or mucosal immunization. These delivery systems may have great potential for novel Tat protein-based vaccines against HIV-1 and hold promise for other protein-based vaccines.

Characterization of immune responses elicited in mice by intranasal co-immunization with HIV-1 Tat, gp140 DeltaV2Env and/or SIV Gag proteins and the nontoxicogenic heat-labile Escherichia coli enterotoxin

The development of a vaccine against HIV/AIDS capable of inducing broad humoral and cellular responses at both systemic and mucosal sites, able to stop or reduce viral infection at the portal of entry, represents the only realistic way to control the infection caused by HIV world-wide. The promising results obtained with the HIV-1 Tat-based vaccines in preclinical and clinical settings, the evidence that a broad immunity against HIV correlates with reduced viral load or virus control, as well as the availability of novel gp140 V2-loop deleted HIV-1 Env (DeltaV2Env) immunogens capable of inducing cross-reactive neutralizing antibodies, have led to the design of new vaccine strategies based on the combination of non-structural and structural proteins. In this study, we demonstrate that immunization with a biologically active HIV-1 Tat protein in combination with the oligomeric HIV-1 gp140 DeltaV2Env and/or SIV Gag proteins, delivered intranasally with the detoxified LTK63 mucosal adjuvant, whose safety has been recently shown in humans, elicits long-lasting local and systemic antibody and cellular immune responses against the co-administered antigens in a fashion similar to immune responses induced by vaccination with Tat, DeltaV2Env and Gag proteins alone. The results indicate lack of antigen interference implying that HIV-1 Tat is an optimal co-antigen for combined vaccine strategies employing DeltaV2Env and/or Gag proteins.