Influence of antigen density and TLR ligands on preclinical efficacy of a VLP-based vaccine against peanut allergy

BACKGROUND

Virus-like particle (VLP) Peanut is a novel immunotherapeutic vaccine candidate for the treatment of peanut allergy. The active pharmaceutical ingredient represents cucumber mosaic VLPs (CuMVTT -VLPs) that are genetically fused with one of the major peanut allergens, Ara h 2 (CuMVTT -Ara h 2). We previously demonstrated the immunogenicity and the protective capacity of VLP Peanut-based immunization in a murine model for peanut allergy. Moreover, a Phase I clinical trial has been initiated using VLP Peanut material manufactured following a GMP-compliant manufacturing process. Key product characterization studies were undertaken here to understand the role and contribution of critical quality attributes that translate as predictive markers of immunogenicity and protective efficacy for clinical vaccine development.

METHOD

The role of prokaryotic RNA encapsulated within VLP Peanut on vaccine immunogenicity was assessed by producing a VLP Peanut batch with a reduced RNA content (VLP Peanut low RNA). Immunogenicity and peanut allergen challenge studies were conducted with VLP Peanut low RNA, as well as with VLP Peanut in WT and TLR 7 KO mice. Furthermore, mass spectrometry and SDS-PAGE based methods were used to determine Ara h 2 antigen density on the surface of VLP Peanut particles. This methodology was subsequently applied to investigate the relationship between Ara h 2 antigen density and immunogenicity of VLP Peanut.

RESULTS

A TLR 7 dependent formation of Ara h 2 specific high-avidity IgG antibodies, as well as a TLR 7 dependent change in the dominant IgG subclass, was observed following VLP Peanut vaccination, while total allergen-specific IgG remained relatively unaffected. Consistently, a missing TLR 7 signal caused only a weak decrease in allergen tolerability after vaccination. In contrast, a reduced RNA content for VLP Peanut resulted in diminished total Ara h 2 specific IgG responses, followed by a significant impairment in peanut allergen tolerability. The discrepant effect on allergen tolerance caused by an absent TLR 7 signal versus a reduced RNA content is explained by the observation that VLP Peanut-derived RNA not only stimulates TLR 7 but also TLR 3. Additionally, a strong correlation was observed between the number of Ara h 2 antigens displayed on the surface of VLP Peanut particles and the vaccine's immunogenicity and protective capacity.

CONCLUSIONS

Our findings demonstrate that prokaryotic RNA encapsulated within VLP Peanut, including antigen density of Ara h 2 on viral particles, are key contributors to the immunogenicity and protective capacity of the vaccine. Thus, antigenicity and RNA content are two critical quality attributes that need to be determined at the stage of manufacturing, providing robust information regarding the immunogenicity and protective capacity of VLP Peanut in the mouse which has translational relevance to the human setting.

Short-course subcutaneous treatment with PQ Grass strongly improves symptom and medication scores in grass allergy

BACKGROUND

A modified grass allergen subcutaneous immunotherapy (SCIT) product with MicroCrystalline Tyrosine and monophosphoryl lipid-A as an adjuvant system (Grass MATA MPL [PQ Grass]) is being developed as short-course treatment of grass-pollen allergic rhinitis (SAR) and/or rhinoconjunctivitis. We sought to evaluate the combined symptom and medication score (CSMS) of the optimized cumulative dose of 27,600 standardized units (SU) PQ Grass in a field setting prior to embarking on a pivotal Phase III trial.

METHODS

In this exploratory, randomized, double-blind, placebo-controlled trial subjects were enrolled across 14 sites (Germany and the United States of America). Six pre-seasonal subcutaneous injections of PQ Grass (using conventional or extended regimens) or placebo were administered to 119 subjects (aged 18-65 years) with moderate-to-severe SAR with or without asthma that was well-controlled. The primary efficacy endpoint was CSMS during peak grass pollen season (GPS). Secondary endpoints included Rhinoconjunctivitis Quality of Life Questionnaire standardized (RQLQ-S) and allergen-specific IgG4 response.

RESULTS

The mean CSMS compared to placebo was 33.1% (p = .0325) and 39.5% (p = .0112) for the conventional and extended regimens, respectively. An increase in IgG4 was shown for both regimens (p < .01) as well as an improvement in total RQLQ-S for the extended regimen (mean change -0.72, p = .02). Both regimens were well-tolerated.

CONCLUSIONS

This trial demonstrated a clinically relevant and statistically significant efficacy response to PQ Grass. Unprecedented effect sizes were reached for grass allergy of up to ≈40% compared to placebo for CSMS after only six PQ Grass injections. Both PQ Grass regimens were considered equally safe and well-tolerated. Based on enhanced efficacy profile extended regime will be progressed to the pivotal Phase III trial.

Ex Vivo Immunomodulatory Effects of Lactobacillus-, Lacticaseibacillus-, and Bifidobacterium-Containing Synbiotics on Human Peripheral Blood Mononuclear Cells and Monocyte-Derived Dendritic Cells in the Context of Grass Pollen Allergy

Sensing of the intestinal microbiota by the host immune system is important to induce protective immune responses. Hence, modification of the gut microbiota might be able to prevent or treat allergies, mediated by proinflammatory Th2 immune responses. The aim was to investigate the ex vivo immunomodulatory effects of the synbiotics Pollagen® and Kallergen®, containing the probiotic bacterial strains Lactobacillus, Lacticaseibacillus and Bifidobacterium, in the context of grass pollen allergy. Peripheral blood mononuclear cells (PBMCs) from grass pollen-allergic patients and healthy controls were stimulated with grass pollen extract (GPE) and synbiotics and Gata3 expression and cytokine secretion analyzed. Monocyte-derived dendritic cells (MoDCs) cells were matured in the presence of GPE and synbiotics, co-cultured with autologous naïve T cells and maturation markers and cytokine secretion analyzed. GPE stimulation of PBMCs from grass pollen-allergic patients resulted in a significant higher production of the Th2 cytokines IL-4, IL-5, IL-9 and IL-13 compared to healthy controls. Gata3+CD4+ T cell induction was independent of the allergic status. The synbiotics promoted IL-10 and IFN-γ secretion and downregulated the GPE-induced Th2-like phenotype. Co-culturing naïve T cells with MoDCs, matured in the presence of GPE and synbiotics, shifted the GPE-induced Th2 cytokine release towards Th1-Th17-promoting conditions in allergic subjects. The investigated synbiotics are effective in downregulating the GPE-induced Th2 immune response in PBMCs from grass pollen-allergic patients as well as in autologous MoDC-T cell stimulation assays. In addition to increased IL-10 release, the data indicates a shift from a Th2- to a more Th1- and Th17-like phenotype.

The next generation virus-like particle platform for the treatment of peanut allergy

BACKGROUND

Allergy to peanut is one of the leading causes of anaphylactic reactions among food allergic patients. Immunization against peanut allergy with a safe and protective vaccine holds a promise to induce durable protection against anaphylaxis caused by exposure to peanut. A novel vaccine candidate (VLP Peanut), based on virus-like particles (VLPs), is described here for the treatment of peanut allergy.

METHODS AND RESULTS

VLP Peanut consist of two proteins: a capsid subunit derived from Cucumber mosaic virus engineered with a universal T cell epitope (CuMV_TT ) and a CuMV_TT subunit fused with peanut allergen Ara h 2 (CuMV_TT -Ara h 2), forming mosaic VLPs. Immunizations with VLP Peanut in both naïve and peanut-sensitised mice resulted in a significant anti-Ara h 2 IgG response. Local and systemic protection induced by VLP Peanut were established in mouse models for peanut allergy following prophylactic, therapeutic and passive immunizations. Inhibition of FcγRIIb function resulted in a loss of protection, confirming the crucial role of the receptor in conferring cross protection against peanut allergens other than Ara h 2.

CONCLUSION

VLP Peanut can be delivered to peanut-sensitized mice without triggering allergic reactions, whilst remaining highly immunogenic and offering protection against all peanut allergens. In addition, vaccination ablates allergic symptoms upon allergen challenge. Moreover, the prophylactic immunization setting conferred the protection against subsequent peanut-induced anaphylaxis, showing the potential for preventive vaccination. This highlights the effectiveness of VLP Peanut as a prospective break-through immunotherapy vaccine candidate towards peanut allergy. VLP Peanut has now entered clinical development with the study PROTECT.

Major Allergen Content In Allergen Immunotherapy Products: The Limited Value of Numbers

The prevalence of allergic disorders drastically increased over the last 50 years that today they can be considered epidemic. At present, allergen-specific immunotherapy (AIT) is the only therapy targeting the underlying cause of allergic disorders, and its superior evidence is based on accumulated data from clinical trials and observational studies demonstrating efficacy and safety. However, several aspects remain unsolved, such as harmonization and standardization of manufacturing and quantification procedures across manufacturers, homogeneous reporting of strength, and also the establishment of international reference standards for many allergens. This article discusses the issues related to the measurement of major allergen content in AIT extracts, raising the question of whether comparison of products by different manufacturers are appropriate as basis to choose among the different AIT products. Allergen standardization in immunotherapy products is critical to ensure quality and thereby safety and efficacy. However, lack of harmonization in manufacturing process, allergen quantification (methodologies and references), national regulatory differences, clinical practice, and labeling shows that the comparison of AIT products solely based on major allergen amounts is not rationale and, in fact, impossible. Moreover, further inherent characteristics of products and their clinical use such as their state of extract modification, addition of adjuvant or adjuvant-system, route of administration (sublingual/subcutaneous) and cumulative dose as per posology (including the volume per administration) need to be taken into account, when rating the information given for a specific product. Finally, only convincing clinical data can serve as the product-specific evaluation, or the basis for cross-product comparability, for individual products.

Immunological effects of adjuvanted low-dose allergoid allergen-specific immunotherapy in experimental murine house dust mite allergy

BACKGROUND

Native allergen extracts or chemically modified allergoids are routinely used to induce allergen tolerance in allergen-specific immunotherapy (AIT), although mechanistic side-by-side studies are rare. It is paramount to balance optimal dose and allergenicity to achieve efficacy warranting safety. AIT safety and efficacy could be addressed by allergen dose reduction and/or use of allergoids and immunostimulatory adjuvants, respectively. In this study, immunological effects of experimental house dust mite (HDM) AIT were investigated applying high-dose HDM extract and low-dose HDM allergoids with and without the adjuvants microcrystalline tyrosine (MCT) and monophosphoryl lipid A (MPL) in a murine model of HDM allergy.

METHODS

Cellular, humoral, and clinical effects of the different AIT strategies were assessed applying a new experimental AIT model of murine allergic asthma based on physiological, adjuvant-free intranasal sensitization followed by subcutaneous AIT.

RESULTS

While low-dose allergoid and high-dose extract AIT demonstrated comparable potency to suppress allergic airway inflammation and Th2-type cytokine secretion of lung-resident lymphocytes and draining lymph node cells, low-dose allergoid AIT was less effective in inducing a potentially protective IgG1 response. Combining low-dose allergoid AIT with MCT or MCT and dose-adjusted MPL promoted Th1-inducing mechanisms and robust B-cell activation counterbalancing the allergic Th2 immune response.

CONCLUSION

Low allergen doses induce cellular and humoral mechanisms counteracting Th2-driven inflammation by using allergoids and dose-adjusted adjuvants. In light of safety and efficacy improvement, future therapeutic approaches may use low-dose allergoid strategies to drive cellular tolerance and adjuvants to modulate humoral responses.

Venom Immunotherapy: From Proteins to Product to Patient Protection

In this review, we outline and reflect on the important differences between allergen-specific immunotherapy for inhalant allergies (i.e., aeroallergens) and venom-specific immunotherapy (VIT), with a special focus on Venomil® Bee and Wasp. Venomil® is provided as a freeze-dried extract and a diluent to prepare a solution for injection for the treatment of patients with IgE-mediated allergies to bee and/or wasp venom and for evaluating the degree of sensitivity in a skin test. While the materials that make up the product have not changed, the suppliers of raw materials have changed over the years. Here, we consolidate relevant historical safety and efficacy studies that used products from shared manufacture supply profiles, i.e., products from Bayer or Hollister-Stier. We also consider the characterization and standardization of venom marker allergens, providing insights into manufacturing controls that have produced stable and consistent quality profiles over many years. Quality differences between products and their impacts on treatment outcomes have been a current topic of discussion and further research. Finally, we review the considerations surrounding the choice of depot adjuvant most suitable to augmenting VIT.

Shaping Modern Vaccines: Adjuvant Systems Using MicroCrystalline Tyrosine (MCT®)

The concept of adjuvants or adjuvant systems, used in vaccines, exploit evolutionary relationships associated with how the immune system may initially respond to a foreign antigen or pathogen, thus mimicking natural exposure. This is particularly relevant during the non-specific innate stage of the immune response; as such, the quality of this response may dictate specific adaptive responses and conferred memory/protection to that specific antigen or pathogen. Therefore, adjuvants may optimise this response in the most appropriate way for a specific disease. The most commonly used traditional adjuvants are aluminium salts; however, a biodegradable adjuvant, MCT®, was developed for application in the niche area of allergy immunotherapy (AIT), also in combination with a TLR-4 adjuvant-Monophosphoryl Lipid A (MPL®)-producing the first adjuvant system approach for AIT in the clinic. In the last decade, the use and effectiveness of MCT® across a variety of disease models in the preclinical setting highlight it as a promising platform for adjuvant systems, to help overcome the challenges of modern vaccines. A consequence of bringing together, for the first time, a unified view of MCT® mode-of-action from multiple experiments and adjuvant systems will help facilitate future rational design of vaccines while shaping their success.

Vaccine against peanut allergy based on engineered virus-like particles displaying single major peanut allergens

BACKGROUND

Peanut allergy is a severe and increasingly frequent disease with high medical, psychosocial, and economic burden for affected patients and wider society. A causal, safe, and effective therapy is not yet available.

OBJECTIVE

We sought to develop an immunogenic, protective, and nonreactogenic vaccine candidate against peanut allergy based on virus-like particles (VLPs) coupled to single peanut allergens.

METHODS

To generate vaccine candidates, extracts of roasted peanut (Ara R) or the single allergens Ara h 1 or Ara h 2 were coupled to immunologically optimized Cucumber Mosaic Virus-derived VLPs (CuMVtt). BALB/c mice were sensitized intraperitoneally with peanut extract absorbed to alum. Immunotherapy consisted of a single subcutaneous injection of CuMVtt coupled to Ara R, Ara h 1, or Ara h 2.

RESULTS

The vaccines CuMVtt-Ara R, CuMVtt-Ara h 1, and CuMVtt-Ara h 2 protected peanut-sensitized mice against anaphylaxis after intravenous challenge with the whole peanut extract. Vaccines did not cause allergic reactions in sensitized mice. CuMVtt-Ara h 1 was able to induce specific IgG antibodies, diminished local reactions after skin prick tests, and reduced the infiltration of the gastrointestinal tract by eosinophils and mast cells after oral challenge with peanut. The ability of CuMVtt-Ara h 1 to protect against challenge with the whole extract was mediated by IgG, as shown via passive IgG transfer. FcγRIIb was required for protection, indicating that immune complexes with single allergens were able to block the allergic response against the whole extract, consisting of a complex allergen mixture.

CONCLUSIONS

Our data suggest that vaccination using single peanut allergens displayed on CuMVtt may represent a novel therapy against peanut allergy with a favorable safety profile.

Correction: Zika Virus-Derived E-DIII Protein Displayed on Immunologically Optimized VLPs Induces Neutralizing Antibodies without Causing Enhancement of Dengue Virus Infection. Vaccines 2019, 7, 72

The authors wish to make the following correction to their paper [...].

Vaccination against Allergy: A Paradigm Shift?

Since the discovery that IgE antibodies mediate allergy, decades of research have unraveled complex mechanisms associated with conventional immunotherapy and the vital protagonists that shape 'immune tolerance' to allergens. Debate exists on what should constitute the dominant effector mechanism in driving rational drug designs for next-generation immunotherapies. As vaccine technology continues to advance, the development of novel vaccines in this area of continued medical need might stand on a threshold of breakthrough inspired by experiments by Dunbar on the passive vaccination of allergic animals more than 100 years ago. In this opinion article, we discuss both novel insights into IgG antibodies as the principle effector modality induced by specific immunotherapy and advances in antigen-carrier design that may catapult allergy treatment into our modern world.

Transcriptome analysis and safety profile of the early-phase clinical response to an adjuvanted grass allergoid immunotherapy

Background

Specific immunotherapy is the only type of disease-modifying treatment, which induces rapid desensitization and long-term sustained unresponsiveness in patients with seasonal allergic rhinoconjunctivitis. The safety and tolerability of a new cumulative dose regimen of 35600 SU Grass MATA MPL for subcutaneous immunotherapy were assessed in pre-seasonal, single-blind, placebo controlled Phase I clinical study. Underlying immunological mechanisms were explored using transcriptome analysis of peripheral blood mononuclear cells.

Methods

Study subjects with a history of moderate to severe seasonal allergic rhinitis and/or conjunctivitis (SAR) due to grass (Pooideae) pollen exposure were randomized on a 1:1 ratio to receive either six 1.0 mL injections of cumulative dose regimen 35600 SU of Grass MATA MPL or placebo. The study consisted of three periods: screening, randomization and treatment and End of Study period. Blood samples were taken for clinical safety laboratory assessments and for the assessment of gene expression analysis during screening visit and End of Study visit. The safety statistics was calculated using Fisher's exact test. Delta Delta Ct method analysis of RT² Profiler PCR Array gene expression results was used to calculate changes in gene expression level. Genes with the absolute value of log₂ fold change greater than ±1.1 and p-value less than 0.05 were identified as differentially expressed and underwent IPA data analysis.

Results

The results of the study indicated that the higher cumulative dose regimen of the immunotherapy was well-tolerated. Changes in gene expression profile were associated with early immune responses implicating innate and adaptive immune mechanisms. Pathways and mechanistic network analysis via IPA mapped differentially expressed genes onto canonical pathways related to T cell differentiation, cytokine signalling and Th1/Th2 activation pathways. The transcriptome findings of the study could be further verified in large-scale field studies in order to explore their potential as predictive markers of successful immunotherapy.

Conclusions

The higher dose cumulative regime 35600 SU of Grass MATA MPL vaccine was well tolerated and safe. Molecular markers IL-27, IL-10, IL-4, TNF, IFNγ, TGFβ and TLR4 were the main predicted molecular drivers of the observed gene expression changes following early stages of SIT with Grass MATA MPL immunotherapy.

Safety Evaluation of PQ Birch Allergy Immunotherapy to Support Product Development

PQ Birch represents an allergen-specific immunotherapy for the treatment of birch pollinosis. It consists of native birch pollen extract chemically modified with glutaldehyde adsorbed to L-tyrosine in its microcrystalline form with addition of the adjuvant Monophosphoryl Lipid A (MPL®). A nonclinical safety testing strategy was designed based upon interpretation of current legislation and regulatory intelligence and comprised genotoxicity studies (bacterial reverse mutation and Chinese hamster ovary micronucleus assays), a rat repeat dose toxicology study and a rabbit local tolerance study. No safety findings of concern were found. Thus, no evidence of genotoxicity was found. Relatively minor, immunostimulatory effects were seen following repeated subcutaneous dosing (once every 2 weeks for 13 weeks) as reversible increased white cell count (notably neutrophils), increased globulin level (resulting in decreased albumin/globulin [A/G] ratio) and increased fibrinogen, as well as minor dose site reaction in the form of inflammatory cell infiltrate. These findings are likely due to the immunostimulatory nature of MPL® and/or the presence of L-tyrosine within the adjuvanted vaccine. Similar dose site inflammatory changes to the injected formulation were also noted in the rabbit local tolerance study.

Zika Virus-Derived E-DIII Protein Displayed on Immunologically Optimized VLPs Induces Neutralizing Antibodies without Causing Enhancement of Dengue Virus Infection

Zika virus (ZIKV) is a flavivirus similar to Dengue virus (DENV) in terms of transmission and clinical manifestations, and usually both viruses are found to co-circulate. ZIKV is usually transmitted by mosquitoes bites, but may also be transmitted by blood transfusion, via the maternal–foetal route, and sexually. After 2015, when the most extensive outbreak of ZIKV had occurred in Brazil and subsequently spread throughout the rest of South America, it became evident that ZIKV infection during the first trimester of pregnancy was associated with microcephaly and other neurological complications in newborns. As a result, the development of a vaccine against ZIKV became an urgent goal. A major issue with DENV vaccines, and therefore likely also with ZIKV vaccines, is the induction of antibodies that fail to neutralize the virus properly and cause antibody-dependent enhancement (ADE) of the infection instead. It has previously been shown that antibodies against the third domain of the envelope protein (EDIII) induces optimally neutralizing antibodies with no evidence for ADE for other viral strains. Therefore, we generated a ZIKV vaccine based on the EDIII domain displayed on the immunologically optimized Cucumber mosaic virus (CuMVtt) derived virus-like particles (VLPs) formulated in dioleoyl phosphatidylserine (DOPS) as adjuvant. The vaccine induced high levels of specific IgG after a single injection. The antibodies were able to neutralise ZIKV without enhancing infection by DENV in vitro. Thus, the here described vaccine based on EDIII displayed on VLPs was able to stimulate production of antibodies specifically neutralizing ZIKV without potentially enhancing disease caused by DENV.

New toxicity testing of PQ grass allergy immunotherapy to support product development

PQ Grass represents an allergen-specific immunotherapy for pre-seasonal treatment of patients with seasonal allergic rhinitis (or rhinoconjunctivitis) with or without mild-to-moderate bronchial asthma. It consists of a native pollen extract for 13 grass species, chemically modified with glutaraldehyde, and adsorbed to l-tyrosine in a microcrystalline form with addition of the adjuvant Monophosphoryl Lipid A (MPL^® ). Previous non-clinical safety testing, including rat repeat dose toxicity in adult and juvenile animals, rat reproductive toxicity and rabbit local tolerance studies showed no safety findings of concern. A new Good Laboratory Practice compliant rat subcutaneous repeat dose toxicity study to evaluate a higher clinical dose and modified posology (once every 2 weeks for 13 weeks) showed no signs of toxicity. As seen in previous studies, relatively minor, immunostimulatory effects were seen such as reversible increased white cell count (notably neutrophils), increased globulin level (resulting in decreased A/G ratio) and increased fibrinogen as well as minor dose site reaction in the form of inflammatory cell infiltrate. These findings are likely due to the immunostimulatory nature of MPL and/or the presence of l-tyrosine within the adjuvanted vaccine. This new toxicity study with PQ Grass therefore supports longer posology with higher dose levels.

Vaccination with nanoparticles combined with micro-adjuvants protects against cancer

BACKGROUND

Induction of strong T cell responses, in particular cytotoxic T cells, is a key for the generation of efficacious therapeutic cancer vaccines which yet, remains a major challenge for the vaccine developing world. Here we demonstrate that it is possible to harness the physiological properties of the lymphatic system to optimize the induction of a protective T cell response. Indeed, the lymphatic system sharply distinguishes between nanoscale and microscale particles. The former reaches the fenestrated lymphatic system via diffusion, while the latter either need to be transported by dendritic cells or form a local depot.

METHODS

Our previously developed cucumber-mosaic virus-derived nanoparticles termed (CuMV_TT-VLPs) incorporating a universal Tetanus toxoid epitope TT830-843 were assessed for their draining kinetics using stereomicroscopic imaging. A nano-vaccine has been generated by coupling p33 epitope as a model antigen to CuMV_TT-VLPs using bio-orthogonal Cu-free click chemistry. The CuMV_TT-p33 nano-sized vaccine has been next formulated with the micron-sized microcrystalline tyrosine (MCT) adjuvant and the formed depot effect was studied using confocal microscopy and trafficking experiments. The immunogenicity of the nanoparticles combined with the micron-sized adjuvant was next assessed in an aggressive transplanted murine melanoma model. The obtained results were compared to other commonly used adjuvants such as B type CpGs and Alum.

RESULTS

Our results showed that CuMV_TT-VLPs can efficiently and rapidly drain into the lymphatic system due to their nano-size of ~ 30 nm. However, formulating the nanoparticles with the micron-sized MCT adjuvant of ~ 5 μM resulted in a local depot for the nanoparticles and a longer exposure time for the immune system. The preclinical nano-vaccine CuMV_TT-p33 formulated with the micron-sized MCT adjuvant has enhanced the specific T cell response in the stringent B16F10p33 murine melanoma model. Furthermore, the micron-sized MCT adjuvant was as potent as B type CpGs and clearly superior to the commonly used Alum adjuvant when total CD8⁺, specific p33 T cell response or tumour protection were assessed.

CONCLUSION

The combination of nano- and micro-particles may optimally harness the physiological properties of the lymphatic system. Since the nanoparticles are well defined virus-like particles and the micron-sized adjuvant MCT has been used for decades in allergen-specific desensitization, this approach may readily be translated to the clinic.

DOPS Adjuvant Confers Enhanced Protection against Malaria for VLP-TRAP Based Vaccines

Vaccination remains the most effective and essential prophylactic tool against infectious diseases. Enormous efforts have been made to develop effective vaccines against malaria but successes remain so far limited. Novel adjuvants may offer a significant advantage in the development of malaria vaccines, in particular if combined with inherently immunogenic platforms, such as virus-like particles (VLP). Dioleoyl phosphatidylserine (DOPS), which is expressed on the outer surface of apoptotic cells, represents a novel adjuvant candidate that may confer significant advantage over existing adjuvants, such as alum. In the current study we assessed the potential of DOPS to serve as an adjuvant in the development of a vaccine against malaria either alone or combined with VLP using Plasmodium falciparum thrombospondin-related adhesive protein (TRAP) as a target antigen. TRAP was chemically coupled to VLPs derived from the cucumber mosaic virus fused to a universal T cell epitope of tetanus toxin (CuMVtt). Mice were immunized with TRAP alone or formulated in alum or DOPS and compared to TRAP coupled to CuMVtt formulated in PBS or DOPS. Induced immune responses, in particular T cell responses, were assessed as the major protective effector cell population induced by TRAP. The protective capacity of the various formulations was assessed using a transgenic Plasmodium berghei expressing PfTRAP. All vaccine formulations using adjuvants and/or VLP increased humoral and T cell immunogenicity for PfTRAP compared to the antigen alone. Display on VLPs, in particular if formulated with DOPS, induced the strongest and most protective immune response. Thus, the combination of VLP with DOPS may harness properties of both immunogenic components and optimally enhance induction of protective immune responses.

Microcrystalline Tyrosine and Aluminum as Adjuvants in Allergen-Specific Immunotherapy Protect from IgE-Mediated Reactivity in Mouse Models and Act Independently of Inflammasome and TLR Signaling

Allergen immunotherapy (AIT) is the only modality that can modify immune responses to allergen exposure, but therapeutic coverage is low. One strategy to improve AIT safety and efficacy is the use of new or improved adjuvants. This study investigates immune responses produced by microcrystalline tyrosine (MCT)–based vaccines as compared with conventional aluminum hydroxide (alum). Wild-type, immune-signaling–deficient, and TCR-transgenic mice were treated with different Ags (e.g., OVA and cat dander Fel d 1), plus MCT or alum as depot adjuvants. Specific Ab responses in serum were measured by ELISA, whereas cytokine secretion was measured both in culture supernatants by ELISA or by flow cytometry of spleen cells. Upon initiation of AIT in allergic mice, body temperature and further clinical signs were used as indicators for anaphylaxis. Overall, MCT and alum induced comparable B and T cell responses, which were independent of TLR signaling. Alum induced stronger IgE and IL-4 secretion than MCT. MCT and alum induced caspase-dependent IL-1β secretion in human monocytes in vitro, but inflammasome activation had no functional effect on inflammatory and Ab responses measured in vivo. In sensitized mice, AIT with MCT-adjuvanted allergens caused fewer anaphylactic reactions compared with alum-adjuvanted allergens. As depot adjuvants, MCT and alum are comparably effective in strength and mechanism of Ag-specific IgG induction and induction of T cell responses. The biocompatible and biodegradable MCT seems therefore a suitable alternative adjuvant to alum-based vaccines and AIT.

Microcrystalline Tyrosine (MCT®): A Depot Adjuvant in Licensed Allergy Immunotherapy Offers New Opportunities in Malaria

Microcrystalline Tyrosine (MCT^®) is a widely used proprietary depot excipient in specific immunotherapy for allergy. In the current study we assessed the potential of MCT to serve as an adjuvant in the development of a vaccine against malaria. To this end, we formulated the circumsporozoite protein (CSP) of P. vivax in MCT and compared the induced immune responses to CSP formulated in PBS or Alum. Both MCT and Alum strongly increased immunogenicity of CSP compared to PBS in both C57BL/6 and BALB/c mice. Challenge studies in mice using a chimeric P. bergei expressing CSP of P. vivax demonstrated clinically improved symptoms of malaria with CSP formulated in both MCT and Alum; protection was, however, more pronounced if CSP was formulated in MCT. Hence, MCT may be an attractive biodegradable adjuvant useful for the development of novel prophylactic vaccines.

The grass pollen season 2015: a proof of concept multi-approach study in three different European cities

Background

Grasses release the most widespread aeroallergens with considerable sensitization rates, while different species produce several pollen concentration peaks throughout the season. This study analyzed the prevalence of grass species in three different European city areas and compared the flowering period of these species with daily pollen concentrations and the symptom loads of grass pollen allergy sufferers.

Methods

The most prevalent grass species in Vienna (Austria), Berlin (Germany) and Turku (Finland) were studied and examined by use of three different approaches: phenology, pollen monitoring and symptom load evaluation. A mobile pollen exposure chamber was employed to observe reaction patterns of grass pollen allergy sufferers to three common grass species evaluated in this study versus placebo.

Results

Common meadow grass (Poa pratensis) and the fescue grass species (Festuca spp.) are important contributors within the grass pollen season. The pollination period of orchard grass (Dactylis glomerata) and false-oat grass (Arrhenatherum elatius) indicated a greater importance in Berlin and Vienna, whereas a broader spectrum of grass species contributed in Turku to the main pollen season. The standardized provocation induced a nasal symptom load, reduction in nasal flow and increased secretion, in contrary to the placebo control group in grass pollen allergic subjects.

Conclusion

The phenological observations, pollen measurements and symptom data evaluation provided unique insights into the contribution of multiple grass species in different European regions. All investigated grass species in the provocation induced rhinitis symptoms of comparable significance, with some degree of variation in symptom patterns.

Molecular fingerprinting of complex grass allergoids: size assessments reveal new insights in epitope repertoires and functional capacities

Background

Subcutaneous allergen immunotherapy (SCIT) is a well-documented treatment for allergic disease which involves injections of native allergen or modified (allergoid) extracts. The use of allergoid vaccines is a growing sector of the allergy immunotherapy market, associated with shorter-course therapy. The aim of this study was the structural and immunological characterisation of group 1 (Lol p 1) IgG-binding epitopes within a complex mix grass allergoid formulation containing rye grass.

Methods

HP-SEC was used to resolve a mix grass allergoid preparation of high molecular weight into several distinct fractions with defined molecular weight and elution profiles. Allergen verification of the HP-SEC allergoid fractions was confirmed by mass spectrometry analysis. IgE and IgG immunoreactivity of the allergoid preparations was explored and Lol p 1 specific IgG-binding epitopes mapped by SPOT synthesis technology (PepSpot™) with structural analysis based on a Lol p 1 homology model.

Results

Grass specific IgE reactivity of the mix grass modified extract (allergoid) was diminished in comparison with the mix grass native extract. A difference in IgG profiles was observed between an intact mix grass allergoid preparation and HP-SEC allergoid fractions, which indicated enhancement of accessible reactive IgG epitopes across size distribution profiles of the mix grass allergoid formulation. Detailed analysis of the epitope specificity showed retention of six Lol p 1 IgG-binding epitopes in the mix grass modified extract.

Conclusion

The structural and immunological changes which take place following the grass allergen modification process was further unravelled revealing distinct IgG immunological profiles. All epitopes were mapped on the solvent exposed area of Lol p 1 homology model accessible for IgG binding. One of the epitopes was identified as an ‘immunodominant’ Lol p 1 IgG-binding epitope (62-IFKDGRGCGSCFEIK-76) and classified as a novel epitope. The results from this study support the concept that modification allows shorter-course therapy options as a result of providing an IgG epitope repertoire important for efficacy. Additionally, the work paves the way to help further develop methods for standardising allergoid platforms.

Electronic supplementary material

The online version of this article (doi:10.1186/s40413-017-0146-3) contains supplementary material, which is available to authorized users.

Comparison of a novel microcrystalline tyrosine adjuvant with aluminium hydroxide for enhancing vaccination against seasonal influenza

Background

Vaccination against seasonal influenza strains is recommended for “high risk” patient groups such as infants, elderly and those with respiratory or circulatory diseases. However, efficacy of the trivalent influenza vaccine (TIV) is poor in many cases and in the event of an influenza pandemic, mono-valent vaccines have been rapidly developed and deployed. One of the main issues with use of vaccine in pandemic situations is the lack of a suitable quantity of vaccine early enough during the pandemic to exert a major influence on the transmission of virus and disease outcome. One approach is to use a dose-sparing regimen which inevitably involves enhancing the efficacy using adjuvants.

Methods

In this study we compare the use of a novel microcrystalline tyrosine (MCT) adjuvant, which is currently used in a niche area of allergy immunotherapy, for its ability to enhance the efficacy of a seasonal TIV preparation. The efficacy of the MCT adjuvant formulation was compared to alum adjuvanted TIV and to TIV administered without adjuvant using a ferret challenge model to determine vaccine efficacy.

Results

The MCT was found to possess high protein-binding capacity. In the two groups where TIV was formulated with adjuvant, the immune response was found to be higher (as determined by HAI titre) than vaccine administered without adjuvant and especially so after challenge with a live influenza virus. Vaccinated animals exhibited lower viral loads (as determined using RT-PCR) than control animals where no vaccine was administered.

Conclusions

The attributes of each adjuvant in stimulating single-dose protection against a poorly immunogenic vaccine was demonstrated. The properties of MCT that lead to the reported effectiveness warrants further exploration in this and other vaccine targets - particularly where appropriate immunogenic, biodegradable and stable alternative adjuvants are sought.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2329-5) contains supplementary material, which is available to authorized users.

A novel microcrystalline tyrosine-adsorbed, mite-allergoid subcutaneous immunotherapy: 1-year follow-up report

Aim: A 1-year follow-up study comparing the safety and tolerability of the dosing schedules, satisfaction and effectiveness of a novel microcrystalline tyrosine-adsorbed mite (Dermatophagoides pteronyssinus)-allergoid subcutaneous immunotherapy (Acarovac Plus™) in 30 adult patients (18–65 years) with allergic rhinitis and/or asthma. Materials & methods: The effectiveness of the product was assessed by nasal provocation test measuring peak nasal inspiratory flow/symptoms, in vitro immunologic changes (IgE, IgG4 and IL-10) and Treatment Satisfaction Questionnaire for Medication. Results: No adverse events were reported during dosing schedules. Significant decreases in symptom scores and drop of peak nasal inspiratory flow in follow-up visits (4 weeks and 1 year) were recorded. Significant increases in IgG4-specific antibody titers and IL-10 were exhibited. Conclusion: Significant decreases in clinical symptoms and immunological parameters were observed, accompanying a high level of patient satisfaction and tolerance.

In vitro evidence for efficacy in food intolerance for the multispecies probiotic formulation Ecologic® Tolerance (Syngut™)

The beneficial effects of probiotics are currently the subject of extensive studies in health and medical research. The aim of this research was to specifically design a new probiotic formulation for supplementation in people suffering from food intolerance. The selection of strains was focussed on the capacity to influence mechanisms of action that are important in development of food intolerance with the following parameters measure: in vitro capacity to produce β-galactosidase, in vitro strengthening of the epithelial barrier, in vitro stimulation of cytokines produced by regulatory T cells, in addition to assessing fundamental quality criteria (stability, gastrointestinal (GI)-survival, multispecies concept, allergen-free). Ecologic®Tolerance/Syngut™ was subsequently developed consisting of a multispecies concept using 4 different probiotic strains (Bifidobacterium lactis W51, Lactobacillus acidophilus W22, Lactobacillus plantarum W21 and Lactococcus lactis W19). Each of these strains demonstrated ability to survive the GI-tract and strain specific effects in producing β-galactosidase, strengthening the gut barrier function after immunological-induced stress and inhibiting Th2 cytokines (IL-4, IL-5 and IL-13 (≥50%), in addition to stimulating interleukin-10 levels; thus, providing in vitro evidence for the efficacy of the selected strains to provide beneficial effects in patients suffering from food intolerance.

Molecular, proteomic and immunological parameters of allergens provide inclusion criteria for new candidates within established grass and tree homologous groups

Background

Our knowledge of allergen structure and function continues to rise and new scientific data on the homology and cross-reactivity of allergen sources should be considered to extend the work of Lorenz et al., 2009 (Int Arch Allergy Immunol. 148(1):1–1, 2009) and the concept of homologous groups. In addition to this, sophisticated techniques such as mass spectrometry (MS) are increasingly utilised to better characterise the complex mix and nature of allergen extracts.

Methods

Homology models were used of Fag s 1 (Beech) and Cyn d 1 (Bermuda grass) and compared with template crystal structures of Bet v 1 and Phl p 1 from the ‘exemplar’ species of Birch and Timothy grass, respectively. ELISA experiments were performed to assess cross-reactivity of Beech (tree) and Bermuda (grass) extracts to rabbit sera raised to either “3-Tree” (Birch, Alder and Hazel) extract or “Grass” (12-grass mix extract), respectively. The comparability of biochemical stability of different allergen sources was assessed through statistical methods for a range of tree and grass species.

Results

Allergen cross-reactivity and/or structural homology have been described providing justification for inclusion of Beech within the Birch homologous tree group. Data from Bermuda grass (Cyn d 1) provides further justification for the inclusion of this species into the homologous group of the sweet grasses. However, further characterisation of relevant allergens from Bermuda grass and, in particular, comparison of cross-reactive patterns between subjects specifically in areas with high abundance of both Pooideae and Chloridoideae is sought.

Conclusion

MS allows the possibility to identify individual proteins or allergens from complex mixes by mass and/or sequence, and this has been extensively applied to the allergen field. New data on the homology, cross-reactivity and biological parameters of allergen sources have been considered to extend the work of Lorenz et al., 2009 in the context of tree and grass species. The concept of homologous groups is certainly dynamic allowing the flexibility and potential in streamlining quality parameters, such as stability profiles, due to extrapolation of exemplar data to a wider range of allergens.

Electronic supplementary material

The online version of this article (doi:10.1186/s40413-015-0069-9) contains supplementary material, which is available to authorized users.

A novel and well tolerated mite allergoid subcutaneous immunotherapy: evidence of clinical and immunologic efficacy

Allergy to house dust mite is one of the most common causes of allergic rhinitis. A novel tyrosine-adsorbed, modified allergen product, Acarovac Plus, developed for the treatment of perennial mite allergy seeks to address the underlying cause of allergic rhinitis in this instance. One of two dosing regimens may be used, either the Conventional Regimen or the Cluster Regimen. We sought to compare the efficacy and safety of a specific immunotherapy, developed for the treatment of perennial mite allergy, administered under a Conventional and Clustered dosing schedule in patients with persistent allergic rhinitis. Thirty adult patients, between 18 and 65 years old, with allergic rhinitis and/or asthma secondary to hypersensitivity to Dermatophagoides pteronyssinus were administered with either conventional or cluster initial regime, with a final visit one week after the last dose administration. The efficacy to the Conventional and Cluster regimens was measured using a Nasal Challenge Test monitoring clinical symptoms and peak nasal inspiratory flow. Total IgE, serum-specific inmunoglobulins (IgE and IgG4) to Dermatophagoides pteronyssinus and relevant cytokines (IFN-γ, IL-4, IL-5, IL-10 and IL-13) were assessed. A Satisfaction Questionnaire (TSQM) was completed after each patient's final visit. The tolerability of the vaccine was assessed monitoring adverse reactions. No adverse events were recorded in either conventional or cluster regime. The specific Nasal Challenge Test led to a decrease in symptom scores and a significant decrease in mean nasal peak inspiratory flow drop was recorded in both dosing regimen groups. A significant increase in IgG4-specific antibody titres was assessed. No significant changes were observed in concentrations of total IgE, specific IgE or cytokines (IFN-γ, IL-4, IL-5, IL-10 and IL-13). Patients declared themselves most satisfied in relation to "Secondary effects", with high overall satisfaction in both groups. Cluster and conventional specific immunotherapy resulted in no adverse reaction(s) and led to similar improvements in immunological parameters, clinical efficacy (Nasal Challenge Test) and high overall satisfaction.

Aluminium in allergen-specific subcutaneous immunotherapy--a German perspective

We are living in an "aluminium age" with increasing bioavailability of the metal for approximately 125 years, contributing significantly to the aluminium body burden of humans. Over the course of life, aluminium accumulates and is stored predominantly in the lungs, bones, liver, kidneys and brain. The toxicity of aluminium in humans is briefly summarised, highlighting links and possible causal relationships between a high aluminium body burden and a number of neurological disorders and disease states. Aluminium salts have been used as depot-adjuvants successfully in essential prophylactic vaccinations for almost 100 years, with a convincing positive benefit-risk assessment which remains unchanged. However, allergen-specific immunotherapy commonly consists of administering a long-course programme of subcutaneous injections using preparations of relevant allergens. Regulatory authorities currently set aluminium limits for vaccines per dose, rather than per treatment course. Unlike prophylactic vaccinations, numerous injections with higher proportions of aluminium-adjuvant per injection are applied in subcutaneous immunotherapy (SCIT) and will significantly contribute to a higher cumulative life dose of aluminium. While the human body may cope robustly with a daily aluminium overload from the environment, regulatory cumulative threshold values in immunotherapy need further addressing. Based on the current literature, predisposing an individual to an unusually high level of aluminium, such as through subcutaneous immunotherapy, has the potential to form focal accumulations in the body with the propensity to exert forms of toxicity. Particularly in relation to longer-term health effects, the safety of aluminium adjuvants in immunotherapy remains unchallenged by health authorities - evoking the need for more consideration, guidance, and transparency on what is known and not known about its safety in long-course therapy and what measures can be taken to prevent or minimise its risks. The possibility of providing an effective means of measuring aluminium accumulation in patients undergoing long-term SCIT treatment as well as reducing their aluminium body burden is discussed.

Probiotics in the treatment of chronic rhinoconjunctivitis and chronic rhinosinusitis

Chronic rhinitis and rhinosinusitis (CRS) are relevant health conditions affecting significant percentages of the western population. They are frequently coexisting and aggravating diseases. Both are chronic, noninfectious, and inflammatory conditions sharing to a certain extent important pathophysiologic similarities. Beneficial effects of probiotics are long known to mankind. Research is beginning to unravel the true nature of the human microbiome and its interaction with the immune system. The growing prevalence of atopic diseases in the developed world led to the proposition of the "hygiene hypothesis." Dysbiosis is linked to atopic diseases; probiotic supplementation is able to alter the microbiome and certain probiotic strains have immunomodulatory effects in favour of a suppression of Th-2 and stimulation of a Th1 profile. This review focuses on randomized, double-blind, placebo-controlled trials investigating clinical parameters in the treatment of chronic rhinitis and CRS. An emerging number of publications demonstrate beneficial effects using probiotics in clinical double-blind placebo-controlled (dbpc) trials in allergic rhinitis (AR). Using probiotics as complementary treatment options in AR seems to be a promising concept although the evidence is of a preliminary nature to date and more convincing trials are needed. There are no current data to support the use of probiotics in non-AR or CRS.

Cold-adapted arsenite oxidase from a psychrotolerant Polaromonas species

Polaromonas sp. str. GM1 is an aerobic, psychrotolerant, heterotrophic member of the Betaproteobacteria and is the only isolate capable of oxidising arsenite at temperatures below 10 °C. Sequencing of the aio gene cluster in GM1 revealed the presence of the aioB and aioA genes, which encode the arsenite oxidase but the regulatory genes typically found upstream of aioB in other members of the Proteobacteria were absent. The GM1 Aio was purified to homogeneity and was found to be a heterodimer. The enzyme contained Mo and Fe as cofactors and had, using the artificial electron acceptor 2,6-dichlorophenolindophenol, a Km for arsenite of 111.70 ± 0.88 μM and a Vmax of 12.16 ± 0.30 U mg(-1), which is the highest reported specific activity for any known Aio. The temperature-activity profiles of the arsenite oxidases from GM1 and the mesophilic betaproteobacterium Alcaligenes faecalis were compared and showed that the GM1 Aio was more active at low temperatures than that of A. faecalis. A homology model of the GM1 Aio was made using the X-ray crystal structure of the Aio from A. faecalis as the template. Structural changes that account for cold adaptation were identified and it was found that these resulted in increased enzyme flexibility and a reduction in the hydrophobicity of the core.

Electrochemically driven catalysis of Rhizobium sp. NT-26 arsenite oxidase with its native electron acceptor cytochrome c552

We describe the catalytic voltammograms of the periplasmic arsenite oxidase (Aio) from the chemolithoautotrophic bacterium Rhizobium sp. str. NT-26 that oxidizes arsenite to arsenate. Electrochemistry of the enzyme was accomplished using its native electron transfer partner, cytochrome c552 (cyt c552), as a mediator. The protein cyt c552 adsorbed on a mercaptoundecanoic acid (MUA) modified Au electrode exhibited a stable, reversible one-electron voltammetric response at +275mV vs NHE (pH6). In the presence of arsenite and Aio the voltammetry of cyt c552 is transformed from a transient response to an amplified sigmoidal (steady state) wave consistent with an electro-catalytic system. Digital simulation was performed using a single set of parameters for all catalytic voltammetries obtained at different sweep rates and various substrate concentrations. The obtained kinetic constants from digital simulation provide new insight into the kinetics of the NT-26 Aio catalytic mechanism.

Ion-specific effects on the interaction between fibronectin and negatively charged mica surfaces

Atomic force microscopy (AFM) imaging and subsequent image analysis have been used to measure the ion-specific and ionic strength effects on the adsorption of fibronectin to mica surfaces in buffer solution. Increasing the concentration of monovalent Na(+) salt solutions is shown to cause a transition from tightly aggregated and "string-of-beads" structures on the mica surface to well dispersed single-molecule adsorption. Studying the effect of two divalent salts, Ni(2+) and Ca(2+), reveals a dramatic enhancement of fibronectin adsorption to mica in buffer solutions containing Ni(2+), but not for Ca(2+). The origin of this ion-specific effect is discussed.

Memory for kinesthetically defined target location: evidence for manual asymmetries

Sixteen right-handed male adults performed a pointing task without vision. The participant's arm was moved passively to one of four targets which was subsequently pointed to following a delay of 1, 2, or 10 s. Our previous research on visual memory for target location showed a rapid decay which was comparable for both hands. The present study of memory for kinesthetic target location found decay for the left hand only. These findings suggest two memory stores for target location information, one visual which decays over time but is accessible to both hands and another based on kinesthetic information which is more stable and limb specific.

Transitive gesture production in apraxia: visual and nonvisual sensory contributions

The production of transitive limb gestures is optimized when the appropriate tool can be physically manipulated. Little research has addressed the independent contributions of visual and nonvisual sources of sensory information to this phenomenon. In this study, 12 control, 37 LHD, and 50 RHD stroke patients performed transitive limb gestures to pantomime (to verbal command with the object visible) and object manipulation. Performance was more accurate in the object manipulation condition, suggesting that haptic and kinesthetic cues are important for transitive gesture production. Various patterns of performance were observed in the stroke groups, indicating that selective damage to the haptic/kinesthetic processing system is possible and common following unilateral stroke.