Incorporation of LpxL1, a detoxified lipopolysaccharide adjuvant, in influenza H5N1 virosomes increases vaccine immunogenicity

Nanoparticles for Topical Application in the Treatment of Skin Dysfunctions-An Overview of Dermo-Cosmetic and Dermatological Products

Nanomaterials (NM) arouse interest in various fields of science and industry due to their composition-tunable properties and the ease of modification. They appear currently as components of many consumer products such as sunscreen, dressings, sports clothes, surface-cleaning agents, computer devices, paints, as well as pharmaceutical and cosmetics formulations. The use of NPs in products for topical applications improves the permeation/penetration of the bioactive compounds into deeper layers of the skin, providing a depot effect with sustained drug release and specific cellular and subcellular targeting. Nanocarriers provide advances in dermatology and systemic treatments. Examples are a non-invasive method of vaccination, advanced diagnostic techniques, and transdermal drug delivery. The mechanism of action of NPs, efficiency of skin penetration, and potential threat to human health are still open and not fully explained. This review gives a brief outline of the latest nanotechnology achievements in products used in topical applications to prevent and treat skin diseases. We highlighted aspects such as the penetration of NPs through the skin (influence of physical-chemical properties of NPs, the experimental models for skin penetration, methods applied to improve the penetration of NPs through the skin, and methods applied to investigate the skin penetration by NPs). The review summarizes various therapies using NPs to diagnose and treat skin diseases (melanoma, acne, alopecia, vitiligo, psoriasis) and anti-aging and UV-protectant nano-cosmetics.

Development of cross-protective influenza a vaccines based on cellular responses

Seasonal influenza vaccines provide protection against matching influenza A virus (IAV) strains mainly through the induction of neutralizing serum IgG antibodies. However, these antibodies fail to confer a protective effect against mismatched IAV. This lack of efficacy against heterologous influenza strains has spurred the vaccine development community to look for other influenza vaccine concepts, which have the ability to elicit cross-protective immune responses. One of the concepts that is currently been worked on is that of influenza vaccines inducing influenza-specific T cell responses. T cells are able to lyse infected host cells, thereby clearing the virus. More interestingly, these T cells can recognize highly conserved epitopes of internal influenza proteins, making cellular responses less vulnerable to antigenic variability. T cells are therefore cross-reactive against many influenza strains, and thus are a promising concept for future influenza vaccines. Despite their potential, there are currently no T cell-based IAV vaccines on the market. Selection of the proper antigen, appropriate vaccine formulation and evaluation of the efficacy of T cell vaccines remains challenging, both in preclinical and clinical settings. In this review, we will discuss the current developments in influenza T cell vaccines, focusing on existing protein-based and novel peptide-based vaccine formulations. Furthermore, we will discuss the feasibility of influenza T cell vaccines and their possible use in the future.

Adjuvant effects elicited by novel oligosaccharide variants of detoxified meningococcal lipopolysaccharides on Neisseria meningitidis recombinant PorA protein: a comparison in mice

Neisseria meningitidis lipopolysaccharide (LPS) has adjuvant properties that can be exploited to assist vaccine immunogenicity. The modified penta-acylated LPS retains the adjuvant properties of hexa-acylated LPS but has a reduced toxicity profile. In this study we investigated whether two modified glycoform structures (LgtE and IcsB) of detoxified penta-acylated LPS exhibited differential adjuvant properties when formulated as native outer membrane vesicles (nOMVs) as compared to the previously described LgtB variant. Detoxified penta-acylated LPS was obtained by disruption of the lpxL1 gene (LpxL1 LPS), and three different glycoforms were obtained by disruption of the lgtB, lgtE or icsB genes respectively. Mice (mus musculus) were immunized with a recombinant PorA P1.7-2,4 (rPorA) protein co-administered with different nOMVs (containing a different PorA serosubtype P1.7,16), each of which expressed one of the three penta-acylated LPS glycoforms. All nOMVs induced IgG responses against the rPorA, but the nOMVs containing the penta-acylated LgtB-LpxL1 LPS glycoform induced significantly greater bactericidal activity compared to the other nOMVs or when the adjuvant was Alhydrogel. Compared to LgtE or IcsB LPS glycoforms, these data support the use of nOMVs containing detoxified, modified LgtB-LpxL1 LPS as a potential adjuvant for future meningococcal protein vaccines.

Nanotechnology in dermatology

The scientific community and general public have been exposed to a series of achievements attributed to a new area of knowledge: Nanotechnology. Both abroad and in Brazil, funding agencies have launched programs aimed at encouraging this type of research. Indeed, for many who come into contact with this subject it will be clear the key role that chemical knowledge will play in the evolution of this subject. And even more, will see that it is a science in which the basic structure is formed by distilling different areas of inter-and multidisciplinary knowledge along the lines of new paradigms. In this article, we attempt to clarify the foundations of nanotechnology, and demonstrate their contribution to new advances in dermatology as well as medicine in general. Nanotechnology is clearly the future.

Lipopolysaccharide engineering in Neisseria meningitidis: structural analysis of different pentaacyl lipid A mutants and comparison of their modified agonist properties

Engineering the lipopolysaccharide (LPS) biosynthetic pathway offers the potential to obtain modified derivatives with optimized adjuvant properties. Neisseria meningitidis strain H44/76 was modified by expression of the pagL gene encoding lipid A 3-O-deacylase from Bordetella bronchiseptica and by inactivation of the lgtB gene encoding the terminal oligosaccharide galactosyltransferase. Mass spectrometry analysis of purified mutant LPS was used for detailed compositional analysis of all present molecular species. This determined that the modified LPS was mainly pentaacylated, demonstrating high efficiency of conversion from the hexaacyl to the 3-O-deacylated form by heterologous lipid A 3-O-deacylase (PagL) expression. MS analyses also provided evidence for expression of only one major oligosaccharide glycoform, which lacked the terminal galactose residue as expected from inactivation of the lgtB gene. The immunomodulatory properties of PagL-deacylated LPS were compared with another pentaacyl form obtained from an lpxL1(-) mutant, which lacks the 2' secondary acyl chain. Although both LPS mutants displayed impaired capacity to induce production of the pro-inflammatory cytokine IL-6 in the monocytic cell line Mono Mac 6, induction of the Toll-interleukin-1 receptor domain-containing adaptor-inducing interferon-β-dependent chemokine interferon-γ-induced protein 10 was largely retained only for the lgtB(-)/pagL(+) mutant. Removal of remaining hexaacyl species exclusively present in lgtB(-)/pagL(+) LPS demonstrated that these minor species potentiate but do not determine the activity of this LPS. These results are the first to indicate a qualitatively different response of human innate cells to pentaacyl lpxL1(-) and pagL(+) LPS and show the importance of detailed structure-function analysis when working with modified lipid A structures. The pagL(+) LPS has significant potential as immune modulator in humans.

Influenza virosomes supplemented with GPI-0100 adjuvant: a potent vaccine formulation for antigen dose sparing

Adjuvants can stimulate vaccine-induced immune responses and can contribute decisively to antigen dose sparing when vaccine antigen production is limited, as for example during a pandemic influenza outbreak. We earlier showed that GPI-0100, a semi-synthetic saponin derivative with amphiphilic structure, significantly stimulates the immunogenicity and protective efficacy of influenza subunit vaccine administered via a systemic route. Here, we evaluated the adjuvant effect of GPI-0100 on a virosomal influenza vaccine formulation. In contrast to influenza subunit vaccine adjuvanted with GPI-0100, virosomal vaccine supplemented with the same dose of GPI-0100 provided full protection of mice against infection at the extremely low antigen dose of 2 × 8 ng hemagglutinin. Overall, adjuvanted virosomes elicited higher antibody and T-cell responses than did adjuvanted subunit vaccine. The enhanced immunogenicity of the GPI-0100-adjuvanted virosomes, particularly at low antigen doses, is possibly due to a physical association of the amphiphilic adjuvant with the virosomal membrane. These results show that a combination of GPI-0100 and a virosomal influenza vaccine formulation is highly immunogenic and allows the use of very low antigen doses without compromising the protective potential of the vaccine.

Adjuvant activity of Sargassum pallidum polysaccharides against combined Newcastle disease, infectious bronchitis and avian influenza inactivated vaccines

This study evaluates the effects of Sargassum pallidum polysaccharides (SPP) on the immune responses in a chicken model. The adjuvanticity of Sargassum pallidum polysaccharides in Newcastle disease (ND), infectious bronchitis (IB) and avian influenza (AI) was investigated by examining the antibody titers and lymphocyte proliferation following immunization in chickens. The chickens were administrated combined ND, IB and AI inactivated vaccines containing SPP at 10, 30 and 50 mg/mL, using an oil adjuvant vaccine as a control. The ND, IB and AI antibody titers and the lymphocyte proliferation were enhanced at 30 mg/mL SPP. In conclusion, an appropriate dose of SPP may be a safe and efficacious immune stimulator candidate that is suitable for vaccines to produce early and persistent prophylaxis.

The design of new adjuvants for mucosal immunity to Neisseria meningitidis B in nasally primed neonatal mice for adult immune response

The aim of this study was to determine the value of detoxified Shiga toxins Stx1 and Stx2 (toxoids of Escherichia coli) as mucosal adjuvants in neonatal mice for immunogenicity against the outer membrane proteins (OMPs) of Neisseria meningitidis B. Mucosal immunization has been shown to be effective for the induction of antigen-specific immune responses in both the systemic and mucosal compartments. Systemic antibody levels (IgG, IgG1, IgG2a, IgG2b, IgM, and IgA) and mucosal IgM and IgA were measured by ELISA using an N. meningitidis as an antigen. In addition, IFN-γ and IL-6 production were measured after stimulated proliferation of immune cells. Intranasal administration elicited a higher anti-OMP IgA response in both saliva and vaginal fluids. Our results suggest that both Stx1 and Stx2 toxoids are effective mucosal adjuvants for the induction of Ag-specific IgG, IgM, and IgA antibodies. The toxoids significantly enhanced the IgG and IgM response against OMPs with a potency equivalent to CT, with the response being characterized by both IgG1 and IgG2a isotypes, and increased IFN-gamma production. Additionally, bactericidal activity was induced with IgG and IgM antibodies of high avidity. These results support the use of the new toxoids as potent inducing adjuvants that are particularly suitable for mucosal immunization.

Nanoparticles in dermatology

Recent advances in the field of nanotechnology have allowed the manufacturing of elaborated nanometer-sized particles for various biomedical applications. A broad spectrum of particles, extending from various lipid nanostructures such as liposomes and solid lipid nanoparticles, to metal, nanocrystalline and polymer particles have already been tested as drug delivery systems in different animal models with remarkable results, promising an extensive commercialization in the coming years. Controlled drug release to skin and skin appendages, targeting of hair follicle-specific cell populations, transcutaneous vaccination and transdermal gene therapy are only a few of these new applications. Carrier systems of the new generation take advantage of improved skin penetration properties, depot effect with sustained drug release and of surface functionalization (e.g., the binding to specific ligands) allowing specific cellular and subcellular targeting. Drug delivery to skin by means of microparticles and nanocarriers could revolutionize the treatment of several skin disorders. However, the toxicological and environmental safety of micro- and nanoparticles has to be evaluated using specific toxicological studies prior to a wider implementation of the new technology. This review aims to give an overview of the most investigated applications of transcutaneously applied particle-based formulations in the fields of cosmetics and dermatology.

A phase 1 study of a meningococcal native outer membrane vesicle vaccine made from a group B strain with deleted lpxL1 and synX, over-expressed factor H binding protein, two PorAs and stabilized OpcA expression

This phase I clinical trial assessed the safety and immunogenicity of a native outer membrane vesicle (NOMV) vaccine prepared from an lpxL1(-) synX(-) mutant of strain 8570(B:4:P1.19,15:L8-5) of Neisseria meningitidis. Additional mutations enhance the expression of factor H binding protein variant 1 (fHbp v.1), stabilize expression of OpcA and introduce a second PorA (P1.22,14). Thirty-six volunteers were assigned to one of four dose groups (10, 25, 50 and 75 mcg, based on protein content) to receive three intramuscular injections at six week intervals with aluminum hydroxide adjuvant. Specific local and systemic adverse events were solicited by diary and at visits on days 2, 7, and 14 after each vaccination. Blood chemistries, complete blood count, and coagulation studies were measured on each vaccination day and again 2 and 14 days later. Blood for ELISA and serum bactericidal assays was drawn two and six weeks after each vaccination. The proportion of volunteers who developed a fourfold or greater increase in bactericidal activity to the wild type parent of the vaccine strain at two weeks after the third dose was 27 out of 34 (0.79, 95% C.I. 0.65-0.93). Against four other group B strains the response rate ranged from 41% to 82% indicating a good cross reactive antibody response. Depletion assays show contributions to bactericidal activity from antibodies to lipooligosaccharide (LOS), fHbp v.1 and OpcA.

Advances in the design and delivery of peptide subunit vaccines with a focus on toll-like receptor agonists

Considerable success has been made with many peptide antigen formulations, and peptide-based vaccines are emerging as the next generation of prophylactic and remedial immunotherapy. However, finding an optimal platform balancing all of the requirements for an effective, specific and safe immune response remains a major challenge for many infectious and chronic diseases. This review outlines how peptide immunogenicity is influenced by the way in which peptides are presented to the immune system, underscoring the need for multifunctional delivery systems that couple antigen and adjuvant into a single construct. Particular attention is given to the ability of Toll-like receptor agonists to act as adjuvants. A survey of recent approaches to developing peptide antigen delivery systems is given, many of which incorporate Toll-like receptor agonists into the design.

Coincorporation of LpxL1 and PagL mutant lipopolysaccharides into liposomes with Neisseria meningitidis opacity protein: influence on endotoxic and adjuvant activity

Wild-type lipopolysaccharide (LPS) of Neisseria meningitidis normally contains six acyl chains. Penta-acylated LPS forms were generated through inactivation of the lpxL1 gene or through the expression of the Bordetella bronchiseptica pagL gene in N. meningitidis. The resulting LPS species, designated LpxL1 LPS and PagL LPS, respectively, display reduced endotoxic activity compared to wild-type LPS. Here, we determined the adjuvant potential of PagL LPS by comparison with the broadly used LpxL1 LPS. We also investigated the potential benefit for adjuvanticity of coincorporating these LPS species, together with the meningococcal opacity-associated protein OpaJ as a model antigen, in a liposomal delivery system. PagL LPS showed a higher endotoxic activity than LpxL1 LPS, and their incorporation into liposomes significantly reduced their endotoxic activity as determined by measuring the induction of interleukin-6 (IL-6) production in a murine macrophage cell line. To determine the adjuvant effect, BALB/c mice were immunized with OpaJ-containing liposomes and either free LPS or LPS coincorporated into the proteoliposomes. OpaJ-containing liposomes adjuvanted with AlPO(4) or not adjuvanted at all were included as control groups. In the appropriate dose, PagL LPS showed a superior adjuvant effect compared with LpxL1 LPS, and for both LPS types, free LPS showed a higher adjuvant effect than when coincorporated into the liposomes, as evidenced by higher titers of IgG2a and IgG2b antibodies against OpaJ(+) meningococci and higher bactericidal titers. In conclusion, PagL LPS is a better adjuvant than LpxL1 LPS, but coincorporation of either LPS into proteoliposomes did not improve their adjuvant activity.

Evaluation of a whole-blood cytokine release assay for use in measuring endotoxin activity of group B Neisseria meningitidis vaccines made from lipid A acylation mutants

Bacterial endotoxin interacts with the human immune system via complex immunological pathways. The evaluation of endotoxicity is important in the development of safe vaccines and immunomodulatory therapeutics. The Limulus amebocyte lysate (LAL) assay is generally accepted by the FDA for use for the quantification of lipopolysaccharide (LPS), while the rabbit pyrogen test (RPT) is used to estimate pyrogenicity during early development and production. Other in vitro assays, such as cytokine release assays with human whole blood (WB) or peripheral blood mononuclear cells (PBMCs), have also been used and may better estimate the human immunological response to products containing novel LPS molecules. In this study, WB and PBMC interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) release assays were used to estimate the endotoxic activities of purified LPS and native outer membrane vesicle (NOMV) vaccines derived from wild-type (hexa-acylated lipid A) and genetically detoxified (penta- and tetra-acylated lipid A) group B Neisseria meningitidis. A method for quantification of the differences in endotoxicity observed in the WB and PBMC assays is elucidated. The LAL assay was shown to be relatively insensitive to lipid A variations, and the RPT was less sensitive than the cytokine release assay with WB. The IL-6 and TNF-alpha assays with WB but not the assays with PBMCs distinguished between vaccines containing LPS from penta- and tetra-acylated strains. The high degree of sensitivity of the WB system to LPS variations and the presumed relevance of the use of human tissues to predict toxicity in humans suggest that this assay may be particularly well suited for the safety evaluation of vaccines and therapeutics containing acylation variants of LPS.

Report of the 5th meeting on the evaluation of pandemic influenza prototype vaccines in clinical trials: World Health Organization, Geneva, Switzerland, 12-13 February 2009

Influenza vaccines are potentially the most efficacious means of mitigating the impact of influenza pandemic and might contribute to the rapid containment of an emerging pandemic virus. On the 12-13 February 2009, the Initiative For Vaccine Research (IVR) of the World Health Organisation convened the 5th meeting on the 'Evaluation of pandemic influenza prototype vaccines in clinical trials' in Geneva. This was a follow-up meeting to the 4th meeting held on 14-15 February 2008 [Girard M, Palkonyay L, Kieny MP. Report of the 4th meeting on the evaluation of pandemic influenza prototype vaccines in clinical trials. Vaccine 2008;26:4975-7], and presentations were made by representatives from industry, academia, and governmental organisations. This year's meeting aimed to update the progress made during the past year on H5N1 and other prototype pandemic vaccines that have undergone clinical trials. A number of vaccine types were covered, including classical egg-derived inactivated vaccines, cell-derived inactivated vaccines, live-attenuated vaccines (LAIV) and vaccines developed using new technologies. The effects of different adjuvants and prime-boosting schedules were important topics, and further data were presented to show that children mount vigorous antibody responses to several H5N1 vaccines. Other subjects presented and discussed were standardisation, and regulatory issues concerning pandemic vaccines.

Animal models for the study of influenza pathogenesis and therapy

Influenza A viruses causes a variety of illnesses in humans. The most common infection, seasonal influenza, is usually a mild, self-limited febrile syndrome, but it can be more severe in infants, the elderly, and immunodeficient persons, in whom it can progress to severe viral pneumonitis or be complicated by bacterial superinfection, leading to pneumonia and sepsis. Seasonal influenza also occasionally results in neurologic complications. Rarely, viruses that have spread from wild birds to domestic poultry can infect humans; such “avian influenza” can range in severity from mild conjunctivitis through the rapidly lethal disease seen in persons infected with the H5N1 virus that first emerged in Hong Kong in 1997. To develop effective therapies for this wide range of diseases, it is essential to have laboratory animal models that replicate the major features of illness in humans. This review describes models currently in use for elucidating influenza pathogenesis and evaluating new therapeutic agents.