Novel T-cell epitopes of ovalbumin in BALB/c mouse: potential for peptide-immunotherapy

The differences of characteristics and allergenicity between natural and recombinant tropomyosin of Macrobrachium nipponense

Tropomyosin (TM) is the main allergen of Macrobrachium nipponense. Recombinant allergens have great prospects in the detection, diagnosis, and treatment of food allergens. The purpose of this study was to compare the differences in structure and allergenicity between natural TM and recombinant TM. Recombinant TM of M. nipponense with a molecular weight of 38 kDa was successfully expressed in the Escherichia coli system. The amino acid sequence as well as secondary structure between natural and recombinant TM were similar, which were verified by mass and CD spectrometry, respectively. Studies showed that both natural TM and recombinant TM had strong allergenicity, and recombinant TM was more allergenic, which could be used as a substitute for natural TM in the diagnosis and treatment of shrimp allergy. This study provided stable and reliable allergen components for the detection of crustacean allergens and the diagnosis and treatment of food allergies caused by crustacean allergens.

Highly Prolonged Release of the Cancer Vaccine and Immunomodulator via a Two-Layer Biodegradable Microneedle for Prophylactic Treatment of Metastatic Cancer

Simultaneous sustained release of cancer vaccines and immunomodulators may effectively trigger durable immune responses and avoid multiple administrations. Here, we established a biodegradable microneedle (bMN) based on a biodegradable copolymer matrix made of polyethylene glycol (PEG) and poly(sulfamethazine ester urethane) (PSMEU). This bMN was applied to the skin and slowly degraded in the epidermis/dermis layers. Then, the complexes composed of a positively charged polymer (DA3), cancer DNA vaccine (pOVA), and toll-like receptor 3 agonist poly(I/C) were synchronously released from the matrix in a pain-free manner. The whole microneedle patch was fabricated with two layers. The basal layer was formed using polyvinyl pyrrolidone/polyvinyl alcohol that could be rapidly dissolved upon applying the microneedle patch to the skin, whereas the microneedle layer was formed by complexes encapsulating biodegradable PEG-PSMEU, which was stuck at the injection site for sustained release of therapeutic agents. According to the results, 10 days is the time for the complexes to be completely released and express specific antigens in antigen-presenting cells in vitro and in vivo. It is noteworthy that this system could successfully elicit cancer-specific humoral immune responses and inhibit metastatic tumors in the lungs after a single shot of immunization.

Optimized Extraction of cAMP From Jujube by Ultra-High Pressure Technology and the Anti-allergic Effect for Peanut Allergy Mouse

Jujube contains abundant cyclic adenosine monophosphate (cAMP). In contrast, the extraction technology of cAMP from jujube is still to be explored. In this study, the ultra-high pressure extraction (UHPE) conditions for obtaining the maximum cAMP yield from jujube were optimized. Orthogonal array design (OAD) was applied to evaluate the effects of three variables (pressure, pressure-holding time, and liquid-to-solid ratio) by UHPE on cAMP yield. The results showed that the optimal cAMP yield (1223.2 μg/g) was derived at 300 MPa, 20 min duration, and a liquid-to-solid ratio of 2.5 ml/g. In addition, as an important functional ingredient in jujube, cAMP has potential anti-allergic effect. To develop the functional characteristics of jujube, the effect of cAMP was characterized in vivo with the Balb/c mouse model of peanut allergy, which was established by subcutaneous injection of crude peanut protein extract (PN). The results showed that treatment with cAMP in PN-sensitized mice suppressed the lesions in jejunal tissues and allergic symptoms and restored spleen index. Meanwhile, cAMP treatment reduced serum levels of specific immunoglobulin E (IgE), histamine, as well as interleukin-4 (IL-4) and stimulated the secretion of tumor necrosis factor-α (TNF-α), whereas the serum levels of interleukin-10 (IL-10) were not affected. Our results suggested that cAMP has an anti-allergic effect in PN-sensitized mice.

Polysaccharide-based nanomedicines for cancer immunotherapy: A review

Cancer immunotherapy is an effective antitumor approach through activating immune systems to eradicate tumors by immunotherapeutics. However, direct administration of "naked" immunotherapeutic agents (such as nucleic acids, cytokines, adjuvants or antigens without delivery vehicles) often results in: (1) an unsatisfactory efficacy due to suboptimal pharmacokinetics; (2) strong toxic and side effects due to low targeting (or off-target) efficiency. To overcome these shortcomings, a series of polysaccharide-based nanoparticles have been developed to carry immunotherapeutics to enhance antitumor immune responses with reduced toxicity and side effects. Polysaccharides are a family of natural polymers that hold unique physicochemical and biological properties, as they could interact with immune system to stimulate an enhanced immune response. Their structures offer versatility in synthesizing multifunctional nanocomposites, which could be chemically modified to achieve high stability and bioavailability for delivering therapeutics into tumor tissues. This review aims to highlight recent advances in polysaccharide-based nanomedicines for cancer immunotherapy and propose new perspectives on the use of polysaccharide-based immunotherapeutics.

Multiple-therapy strategies via polysaccharides-based nano-systems in fighting cancer

Polysaccharide-based biomaterials (e.g., chitosan, dextran, hyaluronic acid, chondroitin sulfate and heparin) have received great attention in healthcare, particularly in drug delivery for tumor therapy. They are naturally abundant and available, outstandingly biodegradable and biocompatible, and they generally have negligible toxicity and low immunogenicity. In addition, they are easily chemically or physically modified. Therefore, PSs-based nanoparticles (NPs) have been extensively investigated for the enhancement of tumor treatment. In this review, we introduce the synthetic pathways of amphiphilic PS derivatives, which allow the constructs to self-assemble into NPs with various structures. We especially offer an overview of the emerging applications of self-assembled PSs-based NPs in tumor chemotherapy, photothermal therapy (PTT), photodynamic therapy (PDT), gene therapy and immunotherapy. We believe that this review can provide criteria for a rational and molecular level-based design of PS-based NPs, and comprehensive insight into the potential of PS-based NPs used in multiple cancer therapies.

The Serpin-like Loop Insertion of Ovalbumin Increases the Stability and Decreases the OVA 323-339 Epitope Processing Efficiency

Chicken ovalbumin (cOVA) has been studied for decades primarily due to the robust genetic and molecular resources that are available for experimental investigations. cOVA is a member of the serpin superfamily of proteins that function as protease inhibitors, although cOVA does not exhibit this activity. As a serpin, cOVA possesses a protease-sensitive reactive center loop that lies adjacent to the OVA 323-339 CD4+ T-cell epitope. We took advantage of the previously described single-substitution variant, OVA R339T, which can undergo the dramatic structural transition observed in serpins, to study how changes in loop size and protein stability influence the processing and presentation of the OVA 323-339 epitope. We observed that the OVA R339T loop insertion increases the stability and protease resistance, resulting in the reduced presentation of the OVA 323-339 epitope in vitro. These findings have implications for the design of more effective vaccines for the treatment of infectious diseases and cancer as well as the development of more robust CD4+ T-cell epitope prediction tools.

Characterization of systemic allergenicity of tropomyosin from shrimp (Macrobrachium nipponense) and anaphylactic reactions in digestive tract

BACKGROUND

Tropomyosin (TM) is the major allergen of crustaceans. The allergenicity of TM from Macrobrachium nipponense (MnTM) and the anaphylactic reaction in the digestive tract are still unclear. The aim of this study was to evaluate the allergenicity of MnTM and the anaphylactic reaction in the digestive tract.

RESULTS

Serum IgE and IgG1 binding ability in the TM group were significantly higher than those in the PBS and CT groups (P < 0.01) and CP group (P < 0.05), while serum IgG and IgG2a binding ability showed no obvious difference between the four groups (P > 0.05). The levels of cytokines IL-4, IL-5 and IL-13 in TM and CP groups were significantly higher than those in PBS and CT groups. Histamine and β-hexosaminidase in the TM and CP groups from basophil cell models were significantly higher than those in the PBS group. The highest mRNA expression of IL-4 and IL-13 was in the jejunum from TM-sensitized mice. Histopathological analysis showed that more immune cells infiltrated into the jejunum than the duodenum and ileum from the TM-sensitized mice.

CONCLUSIONS

MnTM could promote an allergic response in mice and lead to degranulation in basophil cells. The jejunum was more easily affected by MnTM than duodenum and ileum, and the jejunum may be the major site of allergic response in the digestive tract. © 2020 Society of Chemical Industry.

Vaccines as therapies for food allergies

Food allergy is a growing public health epidemic with few available treatments beyond allergen avoidance and rescue medications for accidental exposures. A major focus of therapeutic development for food allergies is allergen-specific immunotherapy (AIT) in which patients are exposed to increasing amounts of allergen in controlled dosing to induce desensitization or tolerance. The work of the past few decades has culminated in the recent FDA approval of a peanut product for oral AIT for peanut allergies. Despite these advances, current AIT protocols are cumbersome, take a long time to reach clinical benefit and often have significant side effects. Therefore, there is a great need to develop new therapeutics for food allergy. One area of research aims to improve AIT through the use of adjuvants which are substances traditionally added to vaccines to stimulate or direct a specific immune response. Adjuvants that induce Th1-polarized and regulatory immune responses while suppressing Th2 immunity have shown the most promise in animal models. The addition of adjuvants to AIT may reduce the amount and frequency of allergen required to achieve clinical benefit and may induce more long-lasting immune responses. In this chapter, we highlight examples of adjuvanted AIT and vaccines in development to treat food allergies.

T-Cell Epitope Immunotherapy in Mouse Models of Food Allergy

Food allergy has been rising in prevalence over the last two decades, affecting more than 10% of the world population. Current management of IgE-mediated food allergy relies on avoidance and rescue medications; research into treatments that are safer and providing guaranteed and durable curative effects is, therefore, essential. T-cell epitope-based immunotherapy holds the potential for modulating food allergic responses without IgE cross-linking. In this chapter, we describe the methods in evaluating the therapeutic capacities of immunodominant T-cell epitopes in animal models of food allergy. Moreover, we explain in detail the methods to measure the allergen-specific antibody levels, prepare single-cell suspension from spleen, and prepare small intestine for immunohistochemical analysis of eosinophils and Foxp3+ cells.

Hypoallergenic Proteins for the Treatment of Food Allergy

PURPOSE OF REVIEW

Food allergy is a growing health problem worldwide that impacts millions of individuals. Current treatment options are limited and strict dietary avoidance remains the standard of care. Immunotherapy using whole, native allergens is under active clinical investigation but harbors the risk of severe side effects including anaphylaxis. Newer food-specific therapies with hypoallergenic proteins may potentially offer safer treatment alternatives, and this review seeks to investigate the evidence supporting the use of these modalities.

RECENT FINDINGS

The utilization of different methods to alter allergen structure and IgE binding leads to reduced allergenicity and decreases the risk for systemic reactions, making the use of potential therapies including extensively heated egg/milk, peptide immunotherapy, recombinant allergen immunotherapy, and DNA vaccines safe and possibly efficacious forms of treatment in food allergy. However, for the majority of these treatment modalities, limited data currently exists looking at the safety and efficacy in human subjects with food allergy. This review provides a comprehensive overview of the current evidence examining the safety and efficacy of hypoallergenic proteins in the treatment of food allergies.

Immunomodulating peptides for food allergy prevention and treatment

Among the most promising strategies currently assayed against IgE-mediated allergic diseases stands the possibility of using immunomodulating peptides to induce oral tolerance toward offending food allergens or even to prevent allergic sensitization. This review focuses on the beneficial effects of food derived immunomodulating peptides on food allergy, which can be directly exerted in the intestinal tract or once being absorbed through the intestinal epithelial barrier to interact with immune cells. Food peptides influence intestinal homeostasis by maintaining and reinforcing barrier function or affecting intestinal cell-signalling to nearby immune cells and mucus secretion. In addition, they can stimulate cells of the innate and adaptive immune system while supressing inflammatory responses. Peptides represent an attractive alternative to whole allergens to enhance the safety and efficacy of immunotherapy treatments. The conclusions drawn from curative and preventive experiments in murine models are promising, although there is a need for more pre-clinical studies to further explore the immunomodulating strategy and its mechanisms and for a deeper knowledge of the peptide sequence and structural requirements that determine the immunoregulatory function.

Hypoallergenic hydrolysates of egg white proteins modulate allergen responses induced ex vivo on spleen cells from sensitized mice

This study describes the in vivo allergenicity of enzymatic hydrolysates of egg white proteins (ovalbumin, lysozyme and ovomucoid) and explores the possibility that they could modulate T cell cytokine responses to egg allergens ex vivo, using splenocytes from BALB/c mice sensitized to individual egg proteins or to their mixtures in different proportions. The hydrolysate of ovalbumin with pepsin could be regarded as a good candidate for peptide-based immunotherapy on the grounds of its reduced ability to trigger allergic symptoms in a passive cutaneous anaphylaxis assay and its potential to reduce Th2 responses (release of IL-4 and IL-5) induced by egg allergens in the spleen cell cultures, but also to enhance Th1 responses (release of TNF-α and IFN-γ). While it is possible to obtain chromatographic fractions containing peptides with different Th2-inhibiting or promoting properties, as judged by cytokine production, selective peptide enrichment did not lead to an increase in the immunomodulating efficiency as compared with the whole ovalbumin hydrolysate, possibly due to the presence in the latter of a combination of immunogenic peptides with synergistic or adjuvant actions.

Egg proteins as allergens and the effects of the food matrix and processing

Hen eggs are an important and inexpensive source of high-quality proteins in the human diet. Egg, either as a whole or its constituents (egg yolk and white), is a key ingredient in many food products by virtue of its nutritional value and unique functional properties, such as emulsifying, foaming, and gelling. Nevertheless, egg is also known because of its allergenic potential and, in fact, it is the second most frequent source of allergic reactions, particularly in children. This review deals with the structural or functional properties of egg proteins that make them strong allergens. Their ability to sensitize and/or elicit allergic reactions is linked to their resistance to gastroduodenal digestion, which ultimately allows them to interact with the intestinal mucosa where absorption occurs. The factors that affect protein digestibility, whether increasing it, decreasing it, or inducing a different proteolysis pattern, and their influence on their capacity to induce or trigger an allergic reaction are discussed. Special attention is paid to the effect of the food matrix and the processing practices on the capacity of egg proteins to modulate the immune response.

Amyloid form of ovalbumin evokes native antigen-specific immune response in the host: prospective immuno-prophylactic potential

Amyloids are highly organized protein aggregates that arise from inappropriately folded versions of proteins or polypeptides under both physiological as well as simulated ambiences. Once thought to be irreversible assemblies, amyloids have begun to expose their more dynamic and reversible attributes depending upon the intrinsic properties of the precursor protein/peptide and experimental conditions such as temperature, pressure, structural modifications in proteins, or presence of chemicals in the reaction mixture. It has been repeatedly proposed that amyloids undergo transformation to the bioactive peptide/protein forms under specific conditions. In the present study, amyloids assembled from the model protein ovalbumin (OVA) were found to release the precursor protein in a slow and steady manner over an extended time period. Interestingly, the released OVA from amyloid depot was found to exhibit biophysical characteristics of native protein and reacted with native-OVA specific monoclonal as well as polyclonal antibodies. Moreover, antibodies generated upon immunization of OVA amyloidal aggregates or fibrils were found to recognize the native form of OVA. The study suggests that amyloids may act as depots for the native form of the protein and therefore can be exploited as vaccine candidates, where slow antigen release over extended time periods is a pre-requisite for the development of desired immune response.

Titrating T-cell epitopes within self-assembled vaccines optimizes CD4+ helper T cell and antibody outputs

Epitope content plays a critical role in determining T-cell and antibody responses to vaccines, biomaterials, and protein therapeutics, but its effects are nonlinear and difficult to isolate. Here, molecular self-assembly is used to build a vaccine with precise control over epitope content, in order to finely tune the magnitude and phenotype of T helper and antibody responses. Self-adjuvanting peptide nanofibers are formed by co-assembling a high-affinity universal CD4+ T-cell epitope (PADRE) and a B-cell epitope from Staphylococcus aureus at specifiable concentrations. Increasing the PADRE concentration from micromolar to millimolar elicited bell-shaped dose-responses that are unique to different T-cell populations. Notably, the epitope ratios that maximize T follicular helper and antibody responses differed by an order of magnitude from those that maximized Th1 or Th2 responses. Thus, modular materials assembly provides a means of controlling epitope content and efficiently skewing the adaptive immune response in the absence of exogenous adjuvant; this approach may contribute to the development of improved vaccines and immunotherapies.

Oral Administration of T Cell Epitope Peptide Inhibits the Systemic IL-4 Response Elicited by an Egg-White Diet in a TCR Transgenic Mouse Model

Oral immunotherapy with T cell epitope peptides is a promising treatment for food allergy. We examined the effect of oral administration of an ovalbumin T cell epitope peptide (OVA323-339) in a TCR transgenic mouse model (OVA23-3 mice). OVA23-3 mice were fed egg-white diet containing ovalbumin and subsequently orally administrated the OVA323-339 peptide. Cytokine measurements revealed that the IL-4 production of splenic CD4⁺ T cells was significantly decreased by feeding the OVA323-339 peptide. Our study suggested that oral administration of the OVA323-339 T cell epitope peptide was capable of inhibiting systemic IL-4 response after elicitation of predominant Th2 responses.

Food allergy diagnosis and therapy: where are we now?

Food allergy is a growing worldwide epidemic that adversely effects up to 10% of the population. Causes and risk factors remain unclear and diagnostic methods are imprecise. There is currently no accepted treatment for food allergy. Therefore, there is an imminent need for greater understanding of food allergies, revised diagnostics and development of safe, effective therapies. Oral immunotherapy provides a particularly promising avenue, but is still highly experimental and not ready for clinical use.

Combination peptide immunotherapy based on T-cell epitope mapping reduces allergen-specific IgE and eosinophilia in allergic airway inflammation

Peptide immunotherapy using soluble peptides containing allergen-derived immunodominant T-cell epitopes holds therapeutic promise for allergic asthma. Previous studies in BALB/c mice using the immunodominant peptide epitope of chicken ovalbumin (p323-339) have been unable to demonstrate therapeutic effects in ovalbumin-induced allergic airway inflammation. We have previously shown that intravenous application of p323-339 can effectively tolerise p323-339-reactive T cells in a non-allergic model in C57BL/6 mice. This study aimed to assess the effects of using p323-339 immunotherapy in a C57BL/6 model of ovalbumin-induced allergic airway inflammation, identify any additional epitopes recognized by the ovalbumin-responsive T-cell repertoire in C57BL/6 mice and assess the effects of combination peptide immunotherapy in this model. Ovalbumin-reactive T-cell lines were generated from ovalbumin-immunized C57BL/6 mice and proliferative responses to a panel of overlapping peptides covering the ovalbumin sequence were assessed. Soluble peptides (singly or combined) were administered intravenously to C57BL/6 mice before the induction of ovalbumin-induced allergic airway inflammation. Peptide immunotherapy using the 323-339 peptide alone did not reduce the severity of allergic airway inflammation. An additional immunodominant T-cell epitope in ovalbumin was identified within the 263-278 sequence. Combination peptide immunotherapy, using the 323-339 and 263-278 peptides together, reduced eosinophilia in the bronchoalveolar lavage and ovalbumin-specific IgE, with apparent reductions in interleukin-5 and interleukin-13. Characterization of the T-cell response to a model allergen has allowed the development of combination peptide immunotherapy with improved efficacy in allergic airway inflammation. This model holds important potential for future mechanistic studies using peptide immunotherapy in allergy.

Vaccines and immunomodulatory therapies for food allergy

The apparent increase in food allergy prevalence has led to a surge in the amount of clinical and basic science research dedicated to the field. At the current time, allergen avoidance remains the cornerstone of treatment; however, recent clinical trials investigating various forms of immunotherapy have opened doors to the possible future application of an active treatment strategy in everyday practice. In addition, improvements in molecular biology have allowed researchers to purify, clone, and modify allergens, thus laying the groundwork for research on vaccines using modified proteins of decreased allergenicity. Finally, various allergen-nonspecific immunomodulatory therapies are also being investigated as a means to alter the immune response to food allergens. With these emerging therapeutic strategies, it is hoped that practitioners will have options in caring for their food-allergic patients in the near future.

The peptide specificity of the endogenous T follicular helper cell repertoire generated after protein immunization

T follicular helper (Tfh) cells potentiate high-affinity, class-switched antibody responses, the predominant correlate of protection from vaccines. Despite intense interest in understanding both the generation and effector functions of this lineage, little is known about the epitope specificity of Tfh cells generated during polyclonal responses. To date, studies of peptide-specific Tfh cells have relied on either the transfer of TcR transgenic cells or use of peptide∶MHC class II tetramers and antibodies to stain TcR and follow limited peptide specificities. In order to comprehensively evaluate polyclonal responses generated from the natural endogenous TcR repertoire, we developed a sorting strategy to separate Tfh cells from non-Tfh cells and found that their epitope-specific responses could be tracked with cytokine-specific ELISPOT assays. The immunodominance hierarchies of Tfh and non-Tfh cells generated in response to immunization with several unrelated protein antigens were remarkably similar. Additionally, increasing the kinetic stability of peptide-MHC class II complexes enhanced the priming of both Tfh and conventional CD4 T cells. These findings may provide us with a strategy to rationally and selectively modulate epitope-specific Tfh responses. By understanding the parameters that control epitope-specific priming, vaccines may be tailored to enhance or focus Tfh responses to facilitate optimal B cell responses.

Oral immunotherapy with immunodominant T-cell epitope peptides alleviates allergic reactions in a Balb/c mouse model of egg allergy

BACKGROUND

  Allergen-specific T-cell epitopes are obvious targets for immunotherapeutic interventions in allergic disease. T-cell epitope peptides given orally may provide a practical way of inducing tolerance and preventing allergy.

OBJECTIVE

  This study investigates oral immunotherapy (OIT) with T-cell epitope peptides of the dominant egg-white allergen ovomucoid (Ovm) in a Balb/c mouse model of egg allergy.

METHODS

  Groups of mice were orally sensitized to Ovm and subsequently administered Ovm T-cell epitopes [single peptide 157-171 (SP) or multiple peptide (157-171)(3) (MP)], followed by oral challenge with Ovm. Outcomes post oral challenge were measured as clinical signs, serum histamine, antibody activity (IgG, IgE, IgG1, IgG2, IgA), cytokines (IL-4, IFN-γ, IL-12p70, IL-10, TGF-β, and IL-17), and T regulatory cells (Tregs).

RESULTS

  Clinical signs were less frequent in both SP and MP groups (P ≤ 0.05). Specific IgE was less and IgA was more in both groups; however, SP-treated mice had less histamine and IgG1 and more IgG2-related antibodies indicating a bias toward the type-1 response (P ≤ 0.05). Concentration of type-2 cytokine interleukin-4 (IL-4) was significantly less in both groups and IL-12p70 and IL-10 were more in SP-treated mice (P ≤ 0.001). Interferon-γ, IL-17, and TGF-β did not differ significantly. There was significant increase in the percentage of CD4+FOXP3+ and CD4+CD25+ cells in the SP group, indicating the significant role of Tregs in immune regulation.

CONCLUSION

  In summary, we demonstrated that OIT with SP and MP comprising the immunodominant regions of Ovm was safe and significantly reduced subsequent frequency of allergy to Ovm, and validated potential use of Ovm T-cell epitope as an immunoregulator.

Encapsulation of antigen in poly(D,L-lactide-co-glycolide) microspheres protects from harmful effects of γ-irradiation as assessed in mice

During the last two decades, synthetic polymers such as poly(lactide-co-glycolide) (PLGA) have been investigated for the development of nano- or microparticles as adjuvants or antigen vehicles. To enable transfer of this technology to human settings, the issue of sterilisation is of central importance. Since most polymers are heat-sensitive, sterilisation of polymeric microspheres for parenteral administration is assured either by costly and laborious aseptical preparation or the more preferred γ-irradiation. Many studies have investigated the effect of γ-irradiation on various physiochemical properties of the microspheres, but investigations on immunological effects are rare. We prepared poly(lactide-co-glycolide) (PLGA) microspheres containing ovalbumin (OVA) and tested the effect of γ-irradiation on the various immunological properties in mice. For reference, OVA was γ-irradiated and tested equivalently. The ability of encapsulated or non-encapsulated OVA to trigger activation of dendritic cells (DCs) was not affected by irradiation. However, while γ-irradiation of free OVA strongly influenced the antigen presentation, encapsulated OVA was not affected by irradiation. γ-Irradiation of OVA also reduced the immunogenicity in mice with regard to OVA-specific IgG1 production. In contrast, the antibody and the T-cell responses in mice immunised with PLGA-encapsulated OVA were similar irrespective of the γ-irradiation status. Hence, encapsulation of antigen into PLGA microspheres protects antigen from the potential detrimental effect of γ-irradiation leading to inactivation or altered immunogenicity. Sterilisation by γ-irradiation therefore enables a cost-effective production of PLGA-based antigen-delivery systems as compared to the more laborious and expensive aseptical production of such vaccines.

Immunotherapy in food allergy

Food allergies are caused by immune responses to food proteins and represent a breakdown of oral tolerance. They can range from mild pruritus to life-threatening anaphylaxis. The only current consensus for treatment is food avoidance, which is fraught with compliance issues. For this reason, there has been recent interest in immunotherapy, which may induce desensitization and possibly even tolerance. Through these effects, immunotherapy may decrease the potential for adverse serious reactions with accidental ingestions while potentially leading to an overall health benefit. In this review, we discuss the mechanisms of food allergy and give an overview of the various immunotherapeutic options and current supporting evidence, as well as look towards the future of potential novel therapeutic modalities.

A self-assembling peptide acting as an immune adjuvant

The development of vaccines and other immunotherapies has been complicated by heterogeneous antigen display and the use of incompletely defined immune adjuvants with complex mechanisms of action. We have observed strong antibody responses in mice without the coadministration of any additional adjuvant by noncovalently assembling a T and B cell epitope peptide into nanofibers using a short C-terminal peptide extension. Self-assembling peptides have been explored recently as scaffolds for tissue engineering and regenerative medicine, but our results indicate that these materials may also be useful as chemically defined adjuvants. In physiological conditions, these peptides self-assembled into long, unbranched fibrils that displayed the epitope on their surfaces. IgG1, IgG2a, and IgG3 were raised against epitope-bearing fibrils in levels similar to the epitope peptide delivered in complete Freund's adjuvant (CFA), and IgM production was even greater for the self-assembled epitope. This response was dependent on self-assembly, and the self-assembling sequence was not immunogenic by itself, even when delivered in CFA. Undetectable levels of interferon-gamma, IL-2, and IL-4 in cultures of peptide-challenged splenocytes from immunized mice suggested that the antibody responses did not involve significant T cell help.

Immunomodulatory effects of egg white enzymatic hydrolysates containing immunodominant epitopes in a BALB/c mouse model of egg allergy

Egg has ben documented as a rich source for the supply of biologically active peptides. This study characterizes the immunomodulatory effects of an egg white enzymatic hydrolysate (EWH) using a BALB/c mouse model of egg allergy. Mice were orally sensitized to egg white and subsequently gavaged with EWH. ELISA results indicated significant reductions of both serum histamine and specific IgE titers in EWH-fed mice, accompanied by a repression of both IL-4 and IFN-gamma production in spleen cell cultures. Similarly, real-time RT-PCR analyses highlighted decreased mRNA expression of IFN-gamma and IL-12 (Th1-biased), as well as lower ratios of IL-4 and IL-13 mRNA (Th2-biased). On the other hand, increased intestinal expressions of TGF-beta and FOXp3 mRNA were determined in EWH-fed mice, suggesting induction of local regulatory mechanisms. The presence of immunodominant epitopes was proposed to be responsible for the immunomodulatory effects observed.