In vivo and T cell cross-reactivity between walnut, cashew and peanut

Allergenicity evaluation of quinoa proteins - A study in Brown Norway rats

The popularity of quinoa seeds has increased in the last decade due to their high nutritional value and natural gluten-free composition. Consumption of new proteins may pose a risk of introducing new allergies. In the present study the immunogenicity and sensitising capacity of quinoa proteins were assessed in a dose-response experiment in Brown Norway rats in comparison to proteins from spinach and peanut. Cross-reactivity between quinoa proteins and known allergens was evaluated by in silico analyses followed by analyses with 11 selected protein extracts and their anti-sera by means of ELISAs and immunoblotting. Further, an in vitro simulated gastro-duodenal digestion was performed. Quinoa proteins were found to have an inherent medium to high immunogenicity and sensitising capacity, being able to induce specific IgG1 and IgE levels higher than spinach but lower than peanut and elicit reactions of clinical relevance similar to peanut. Quinoa proteins were generally shown to resist digestion and retain capacity to bind quinoa-specific antibodies. Quinoa proteins were shown to be cross-reactive with peanut and tree nut allergens as high sequence homology and antibody cross-binding were demonstrated. Present study suggests that quinoa pose a medium to high level of allergenicity that should be further investigated in human studies.

Identification and Structure of Epitopes on Cashew Allergens Ana o 2 and Ana o 3 Using Phage Display

BACKGROUND

Cashew (Anacardium occidentale L.) is a commercially important plant. Cashew nuts are a popular food source that belong to the tree nut family. Tree nuts are one of the eight major food allergens identified by the Food and Drug Administration in the USA. Allergies to cashew nuts cause severe and systemic immune reactions. Tree nut allergies are frequently fatal and are becoming more common.

AIM

We aimed to identify the key allergenic epitopes of cashew nut proteins by correlating the phage display epitope prediction results with bioinformatics analysis.

DESIGN

We predicted and experimentally confirmed cashew nut allergen antigenic peptides, which we named Ana o 2 (cupin superfamily) and Ana o 3 (prolamin superfamily). The Ana o 2 and Ana o 3 epitopes were predicted using DNAstar and PyMoL (incorporated in the Swiss-model package). The predicted weak and strong epitopes were synthesized as peptides. The related phage library was built. The peptides were also tested using phage display technology. The expressed antigens were tested and confirmed using microtiter plates coated with pooled human sera from patients with cashew nut allergies or healthy controls.

RESULTS

The Ana o 2 epitopes were represented by four linear peptides, with the epitopes corresponding to amino acids 108-111, 113-119, 181-186, and 218-224. Furthermore, the identified Ana o 3 epitopes corresponding to amino acids 10-24, 13-27, 39-49, 66-70, 101-106, 107-114, and 115-122 were also screened out and chosen as the key allergenic epitopes.

DISCUSSION

The Ana o 3 epitopes accounted for more than 40% of the total amino acid sequence of the protein; thus, Ana o 3 is potentially more allergenic than Ana o 2.

CONCLUSIONS

The bioinformatic epitope prediction produced subpar results in this study. Furthermore, the phage display method was extremely effective in identifying the allergenic epitopes of cashew nut proteins. The key allergenic epitopes were chosen, providing important information for the study of cashew nut allergens.

Mouse Models of Food Allergy in the Pursuit of Novel Treatment Modalities

The prevalence of IgE-mediated food allergies has increased dramatically in the past three decades, now affecting up to 10% of the US population. IgE-mediated food allergy is an immunologic disease, involving a variety of cells, including B and T cells, mast cells, basophils, ILC2s, and epithelial cells. Mouse models of food allergy mimic the overall immunologic processes known to exist in humans. Due to the limitations of invasive sampling of human tissue and the similarities of the human and mouse immune systems, comprehensive pathogenesis studies of food allergy have been performed in mouse models. Mouse models have been effective in elucidating the roles of non-oral routes of sensitization and identifying key cells and molecules involved in allergic sensitization. Furthermore, the development of novel therapeutic approaches for food allergy has been accelerated through the use of pre-clinical mouse models. Despite the groundbreaking findings stemming from research in mice, there are continued efforts to improve the translational utility of these models. Here, we highlight the achievements in understanding food allergy development and efforts to bring novel treatment approaches into clinical trials.

Model of Walnut Allergy in CC027/GeniUnc Mice Recapitulates Key Features of Human Disease

Tree nut allergies affect 1% of the United States population, are often severe in nature and rarely outgrown. Despite the severity and prevalence, there are no FDA-approved treatments for tree nut allergy. Development of a therapeutic would be expedited by having a mouse model that mimics the human disease. We utilized the CC027/GeniUnc mouse strain, which was previously identified as an orally reactive model of peanut allergy, to develop a model of walnut allergy. Mice were sensitized with walnut and cholera toxin for 4 weeks and subsequently challenged by oral gavage. Blood samples were collected to measure serum IgE. Walnut-sensitized mice produced high levels of walnut-IgE and were cross-sensitized to pecan. Oral challenges with walnut resulted in severe anaphylaxis and accompanying allergic symptoms. Importantly, pecan challenges also led to severe allergic reactions, indicating cross-reactivity to pecan. Overall, this novel mouse model reproduces key characteristics of human walnut allergy, which provides a platform to develop novel therapies and better understand sensitization mechanisms.

Epitopes with similar physicochemical properties contribute to cross reactivity between peanut and tree nuts

Many individuals with peanut (PN) allergy have severe reactions to tree nuts (TN) such as walnuts or cashews. Although allergenic proteins in TN and PN have overall low identity, they share discrete sequences similar in physicochemical properties (PCP) to known IgE epitopes. Here, PCP-consensus peptides (cp, 13 aa and 31 aa) were identified from an alignment of epitope rich regions of walnut vicilin, Jug r 2, leader sequence (J2LS) and cross-reactive epitopes in the 2S albumins of peanut and synthesized. A peptide similarity search in the Structural Database of Allergenic Proteins (SDAP) revealed a network of peptides similar (low property distance, PD) to the 13 aa cp (13cp) in many different plant allergens. Peptides similar to the 13cp in PN and TN allergens bound IgE from sera of patients allergic to PN and TN in peptide microarray analysis. The 13cp was used to produce a rabbit consensus peptide antibody (cpAB) that detected proteins containing repeats similar to the 13cp in western blots of various nut extracts, in which reactive proteins were identified by mass spectrometry. The cpAB bound more specifically to allergens and nut extracts containing multiple repeats similar to the 13 cp, such as almond (Pru du 6), peanut (Ara h 2) and walnut (Jug r 2). IgE binding to various nut extracts is inhibited by recombinant J2LS sequence and synthetic 31cp. Thus, several repeated sequences similar to the 13cp are bound by IgE. Multiple similar repeats in several allergens could account for reaction severity and clinically relevant cross-reactivity to PN and TN. These findings may help improve detection, diagnostic, and therapeutic tools.

IgE Cross-Reactivity of Cashew Nut Allergens

BACKGROUND

Allergic sensitisation towards cashew nut often happens without a clear history of eating cashew nut. IgE cross-reactivity between cashew and pistachio nut is well described; however, the ability of cashew nut-specific IgE to cross-react to common tree nut species and other Anacardiaceae, like mango, pink peppercorn, or sumac is largely unknown.

OBJECTIVES

Cashew nut allergic individuals may cross-react to foods that are phylogenetically related to cashew. We aimed to determine IgE cross-sensitisation and cross-reactivity profiles in cashew nut-sensitised subjects, towards botanically related proteins of other Anacardiaceae family members and related tree nut species.

METHOD

Sera from children with a suspected cashew nut allergy (n = 56) were assessed for IgE sensitisation to common tree nuts, mango, pink peppercorn, and sumac using dot blot technique. Allergen cross-reactivity patterns between Anacardiaceae species were subsequently examined by SDS-PAGE and immunoblot inhibition, and IgE-reactive allergens were identified by LC-MS/MS.

RESULTS

From the 56 subjects analysed, 36 were positive on dot blot for cashew nut (63%). Of these, 50% were mono-sensitised to cashew nuts, 19% were co-sensitised to Anacardiaceae species, and 31% were co-sensitised to tree nuts. Subjects co-sensitised to Anacardiaceae species displayed a different allergen recognition pattern than subjects sensitised to common tree nuts. In pink peppercorn, putative albumin- and legumin-type seed storage proteins were found to cross-react with serum of cashew nut-sensitised subjects in vitro. In addition, a putative luminal binding protein was identified, which, among others, may be involved in cross-reactivity between several Anacardiaceae species.

CONCLUSIONS

Results demonstrate the in vitro presence of IgE cross-sensitisation in children towards multiple Anacardiaceae species. In this study, putative novel allergens were identified in cashew, pistachio, and pink peppercorn, which may pose factors that underlie the observed cross-sensitivity to these species. The clinical relevance of this widespread cross-sensitisation is unknown.

Jug r 6 is the allergenic vicilin present in walnut responsible for IgE cross-reactivities to other tree nuts and seeds

Walnuts are ranked high in the list of the culprit foods inducing severe allergic reactions. Jug r 2 has been identified as a major allergen in common walnut by cDNA cloning from a somatic cell line. So far, studies were performed on the allergenic activity of recombinant Jug r 2, yet there is still no evidence about the physicochemical characteristics of the natural allergen. Therefore, we aimed to purify and deeply characterize natural Jug r 2 and to assess IgE cross-reactivity among vicilins from different tree nuts. Extensive mass spectrometry analysis of the obtained purified vicilin allowed identification of the protein sequence that displayed only 44% identity to Jug r 2. The newly identified vicilin (Jug r 6) was recognized by IgE of 26% in walnut allergic patients’ sera tested. In contrast to Jug r 2, Jug r 6 displayed a remarkable level of cross-reactivity when tested with homologues from hazelnut, sesame and pistachio. It is the first report showing the necessity of proteomic studies to improve allergy component resolved diagnosis.

Tree nut allergies: Allergen homology, cross-reactivity, and implications for therapy

Tree nut allergy is a potentially life-threatening disease that is increasing in prevalence, now affecting 1% of the general population in the United States. While other food allergies often resolve spontaneously, tree nut allergies are outgrown in less than 10% of cases. Due to the likelihood of cross-sensitization to multiple tree nut allergens, the current treatment guideline is strict avoidance of all nuts once one tree nut allergy has been diagnosed. For example, walnut and pecan are highly cross-reactive, along with cashew and pistachio, but the extent of clinical, IgE-mediated cross-reactivity among other tree nuts remains unclear, therefore making avoidance of all tree nuts a safe approach. There have been recent advances in immunotherapy for food allergies. For instance, there are investigational immunotherapies for milk, egg and peanut allergies, specifically oral immunotherapy, sublingual immunotherapy and epicutaneous immunotherapy. However, there are no large randomized controlled clinical trials for tree nut allergies. Even though there has been less research into tree nut allergy immunotherapies, the evidence of T-cell cross-reactivity among tree nuts exists in animal models and in T cells from allergic patients indicates that immunotherapeutic interventions may be possible. Here, we review the literature regarding epidemiology, allergen homology and cross-reactivity among tree nuts, and explore how current findings can be employed for effective therapy.

Food allergen extracts to diagnose food-induced allergic diseases: How they are made

OBJECTIVE

To review the manufacturing procedures of food allergen extracts and applicable regulatory requirements from government agencies, potential approaches to standardization, and clinical application of these products. The effects of thermal processing on allergenicity of common food allergens are also considered.

DATA SOURCES

A broad literature review was conducted on the natural history of food allergy, the manufacture of allergen extracts, and the allergenicity of heated food. Regulations, guidance documents, and pharmacopoeias related to food allergen extracts from the United States and Europe were also reviewed.

STUDY SELECTIONS

Authoritative and peer-reviewed research articles relevant to the topic were chosen for review. Selected regulations and guidance documents are current and relevant to food allergen extracts.

RESULTS

Preparation of a food allergen extract may require careful selection and identification of source materials, grinding, defatting, extraction, clarification, sterilization, and product testing. Although extractions for all products licensed in the United States are performed using raw source materials, many foods are not consumed in their raw form. Heating foods may change their allergenicity, and doing so before extraction may change their allergenicity and the composition of the final product.

CONCLUSION

The manufacture of food allergen extracts requires many considerations to achieve the maximal quality of the final product. Allergen extracts for a select number of foods may be inconsistent between manufacturers or unreliable in a clinical setting, indicating a potential area for future improvement.

B cells establish, but do not maintain, long-lived murine anti-peanut IgE(a)

BACKGROUND

Peanut allergy (PNA) has been reported to be transferred to tolerant recipients through organ and bone marrow (BM) transplantation. The roles T and B cells play in establishing, and the roles B cell subsets play in maintaining lifelong anti-peanut IgE levels are unknown.

OBJECTIVES

To determine the cellular requirements for the transfer of murine PNA and to determine the role CD20(+) cells play in maintaining long-lived anti-peanut IgE levels.

METHODS

We developed a novel adoptive transfer model to investigate the cellular requirements for transferring murine PNA. We also treated peanut-allergic (PA) mice with anti-CD20 antibody and measured IgE levels throughout treatment.

RESULTS

Purified B220(+) cells from PA splenocytes and purified CD4(+) cells from naïve (NA) splenocytes are the minimal requirements for the adoptive transfer of PNA. Prolonged treatment of allergic mice with anti-CD20 antibody results in significant depletion of B cell subsets but does not affect anti-peanut IgE levels, symptoms, or numbers of IgE antibody secreting cells (ASCs) in the BM. Adoptive transfer of BM and spleen cells from allergic donors treated with anti-CD20 antibody does not result in the transfer of PNA in NA recipients, demonstrating that anti-CD20 antibody treatment depletes B cells capable of differentiating into peanut-specific IgE ASCs.

CONCLUSIONS AND CLINICAL RELEVANCE

Peanut allergy can be established in a NA hosts with B220(+) cells from PA donors and CD4(+) cells from peanut-NA donors. However, long-term depletion of B220(+) cells with anti-CD20 antibody does not affect anti-peanut IgE levels. These results highlight a novel role for B cells in the development of PNA and provide evidence that long-lived anti-peanut IgE levels may be maintained by long-lived ASCs.

Prolonged Treatment of Peanut-Allergic Mice with Bortezomib Significantly Reduces Serum Anti-Peanut IgE but Does Not Affect Allergic Symptoms

BACKGROUND

Anti-peanut immunoglobulin E (anti-Pn IgE) can persist throughout life, suggesting that this condition could be maintained by long-lived antibody-secreting cells (ASCs). To determine the role of long-lived ASCs, peanut-allergic mice underwent prolonged treatment with the proteasome inhibitor, bortezomib (Bz).

METHODS

Intravenous Bz was given twice weekly for 21 weeks to peanut-allergic mice. During treatment, serum anti-Pn IgE was measured, and the mice were rechallenged at the end of treatment. Cell populations were measured, and Pn-specific IgG, total IgG, and total IgE ASCs were enumerated in the bone marrow (BM) and spleen (SPL).

RESULTS

Prolonged treatment with Bz significantly reduced serum anti-Pn IgE and IgG1 but did not affect symptoms following challenge with Pn, even in mice with undetectable serum anti-Pn IgE. Numbers of CD138+ cells were significantly reduced in the BM but were unaffected in the SPL. Unexpectedly, Bz did not affect numbers of Pn-specific IgG, total IgG, or total IgE ASCs in either the BM or SPL.

CONCLUSIONS

Cells that maintain long-lived serum anti-Pn IgE are sensitive to Bz. However, prolonged depletion of serum Pn-specific IgE does not result in a decrease of symptoms following challenge with Pn.

Component-Resolved Diagnosis of Peanut Allergy and Its Possible Origins of Sensitization in China

BACKGROUND

Clinical and immunological characteristics of food allergies vary depending on geographic regions. Little is known about peanut allergy in China. The aim of this study was to investigate the peanut sensitization profile in China.

METHODS

Thirty-eight participants with immunoglobulin E (IgE)-positive responses to peanuts (peanut-sensitized) were included in our study, and clinical characteristics were evaluated. Total and specific IgE reactivity against peanuts, other plant-derived foods, pollens, and related allergen components were determined.

RESULTS

Eighteen patients were symptomatic when exposed to peanuts. The majority of them presented with systemic reactions. More than half of the peanut-sensitized subjects also suffered from mugwort pollinosis and peach allergy. In patients with both peanut and peach allergies, reactions to peanuts were the same as or severer than those to peaches. Positivity rates of IgE response to rAra h 1-3, 8, and 9 in the peanut allergy group were 5.6, 11.1, 5.6, 22.2, and 83.3%, respectively. 66.7% (12/18) of the peanut-allergic patients were monosensitized to rAra h 9. Anti-nArt v 3 [mugwort nonspecific lipid transfer protein (nsLTP)] IgE positivity in the peanut allergy group was significantly higher than that in the asymptomatic peanut-sensitized group. In Ara h 9 (peanut nsLTP)-sensitized patients with mugwort pollinosis, anti-nArt v 3 IgE levels were remarkably higher than anti-rAra h 9 (peanut nsLTP) IgE levels as well as anti-Pru p 3 (peach nsLTP) IgE levels.

CONCLUSIONS

Ara h 9 was the major allergen of peanut, and Ara h 9 monosensitization was the most common peanut sensitization pattern in our population. Furthermore, there was a strong correlation between peanut sensitization and mugwort pollinosis, as well as peach allergy, in our country.

Heterogeneous responses and cross reactivity between the major peanut allergens Ara h 1, 2,3 and 6 in a mouse model for peanut allergy

BACKGROUND

The relative contribution and the relation between individual peanut allergens in peanut allergic responses is still matter of debate. We determined the individual contribution of peanut proteins to B, T cell and allergic effector responses in a mouse model for peanut allergy.

METHODS

Mice were immunized and challenged by oral gavage with peanut protein extract or isolated allergens Ara h 1, 2, 3 and 6 followed by assessment of food allergic manifestations. In addition, T cell responses to the individual proteins were measured by an in vitro dendritic cell-T cell assay.

RESULTS

Sensitization with the individual peanut proteins elicited IgE responses with specificity to the allergen used as expected. However, cross reactivity among Ara h 1, 2, 3 and 6 was observed. T cell re-stimulations with peanut extract and individual peanut proteins also showed cross reactivity between Ara h 1, 2, 3 and 6. Despite the cross reactivity at the IgE level, only Ara h 2 and 6 were able to elicit mast cell degranulation after an oral challenge. However, after systemic challenge, Ara h 1, 2 and 6 and to lesser extent Ara h 3 were able to elicit anaphylactic responses.

CONCLUSIONS

Ara h 1, 2, 3 and 6 sensitize via the intra-gastric route, but differ in their capacity to cause allergic effector responses. Interestingly, extensive cross reactivity at T cell and antibody level is observed among Ara h 1, 2, 3 and 6, which may have important implications for the diagnosis and therapy of peanut allergy. Awareness about the relative contribution of individual peanut allergens and cross reactivity between these allergens is of importance for current research in diagnostics and therapeutics for and the mechanism of peanut allergy.

Peanut allergy is common among hazelnut-sensitized subjects but is not primarily the result of IgE cross-reactivity

BACKGROUND

Hazelnut and peanut are botanically unrelated foods, but patients are often sensitized and allergic to both, for reasons that are not well understood.

METHODS

To investigate molecular cosensitization and cross-reactivity to peanut in hazelnut-sensitized individuals, children (n = 81) and adults (n = 80) were retrospectively selected based on sensitization to hazelnut. IgE to hazelnut extract, Cor a 1, 8, 9 and 14, to peanut extract, Ara h 1, 2, 3, 8 and 9, and to Bet v 1 was determined by ImmunoCAP. Allergy to hazelnut and peanut was established by DBPCFC and/or detailed clinical history. Patients were either tolerant or displayed subjective or objective symptoms to either food. IgE cross-reactivity between hazelnut and peanut storage proteins was assessed by reciprocal ImmunoCAP inhibition experiments.

RESULTS

Of the 161 hazelnut-sensitized subjects, 109 (68%) were also sensitized to peanut, and 73 (45%) had clinical expression of allergy to peanut that was not associated with the presence or severity of hazelnut allergy. Instead, it was associated with IgE reactivity to peanut storage proteins, in particular Ara h 2. No cross-reactivity could be detected between Ara h 2 and Cor a 14, and 2 of 13 subjects displayed extensive cross-reactivity between 11S globulins; in plasma of both individuals, Ara h 3 almost completely inhibited IgE binding to Cor a 9.

CONCLUSIONS

Peanut allergy is not primarily the result of IgE cross-reactivity to hazelnut storage proteins. IgE to Cor a 14 and Ara h 2 may serve as useful markers of primary sensitization to hazelnut and peanut, respectively.

Effects of a pre-existing food allergy on the oral introduction of food proteins: findings from a murine model

Cashew-allergic mice develop elevated walnut-specific IgE upon oral feeding of walnut proteins. Ingestion of tree nuts in the presence of a known nut allergy could lead to additional sensitizations and anaphylaxis following subsequent exposure.

Cross-reactivity of peanut allergens

Peanut seeds are currently widely used as source of human food ingredients in the United States of America and in European countries due to their high quality protein and oil content. This article describes the classification and molecular biology of peanut seed allergens with particular reference to their cross-reactivities. Currently, the IUIS allergen nomenclature subcommittee accepts 12 peanut allergens. Two allergens belong to the cupin and four to the prolamin superfamily, and six are distributed among profilins, Bet v 1-like proteins, oleosins, and defensins. Clinical observations frequently report an association of peanut allergy with allergies to legumes, tree nuts, seeds, fruits and pollen. Molecular cross-reactivity has been described between members of the Bet v 1-like proteins, the non-specific lipid transfer proteins, and the profilins. This review also addresses the less well-studied cross-reactivity between cupin and prolamin allergens of peanuts and of other plant food sources and the recently discovered cross-reactivity between peanut allergens of unrelated protein families.

Molecular diagnosis of peanut allergy

Peanut allergy prevalence has increased in developed countries over the last few decades in the frame of the allergy epidemics, currently affecting 1-2% of children. While less frequent in developing countries, its prevalence is rising as these countries adopt a more westernized lifestyle. There is no curative treatment for peanut allergy at present so patient management relies on peanut avoidance, which requires an accurate diagnosis. Recent progress in peanut allergy diagnosis was made with the introduction of component resolved diagnosis that allows the assessment of IgE specific to individual peanut allergens. Component-resolved diagnosis needs to be interpreted in the context of clinical data but overall increases the diagnostic accuracy, as described in the typical cases that we present. Novel diagnostic tools have been proposed recently, such as the basophil activation test, mRNA expression and resonance magnetic evaluation of biomarkers.

Type B CpG oligodeoxynucleotides induce Th1 responses to peanut antigens: modulation of sensitization and utility in a truncated immunotherapy regimen in mice

SCOPE

Peanut allergy stems from a Th2-biased immune response to peanut allergens leading to IgE production and allergic reactions upon ingestion.

METHODS AND RESULTS

A model of peanut allergy in C3H/HeJ mice was used to assess whether type A, B, or C CpG oligodeoxynucleotide (ODN) molecules would be effective in: (i) a prophylactic approach to prevent peanut allergy when administered simultaneously with a Th2-skewing adjuvant, and (ii) a therapeutic model to allow for shortened immunotherapy. Type B ODNs were extremely effective in inhibiting anaphylaxis in the sensitization protocol as evidenced by differences in symptom scores, body temperature, and mouse mast cell protease 1 release compared to sham treatment. In the therapeutic model, co-administration of type B ODN plus peanut proteins was highly effective in reducing anaphylactic reactions in mice with established peanut allergy. The therapeutic effect was accompanied by an increase in IFN-γ and peanut-IgG2a, without a significant decrease in peanut IgE or IL-4 responses.

CONCLUSION

CpG ODNs, especially type B, were highly effective in inducing Th1 responses in mice undergoing induction of peanut allergy, as well as in mice undergoing therapy for established peanut allergy. Interestingly, the IgE response was not significantly altered, suggesting that IgG antibodies may be enough to prevent peanut-induced anaphylaxis.

Pepsinized cashew proteins are hypoallergenic and immunogenic and provide effective immunotherapy in mice with cashew allergy

BACKGROUND

IgE-mediated allergic reactions to cashews and other nuts can trigger life-threatening anaphylaxis. Proactive therapies to decrease reaction severity do not exist.

OBJECTIVES

We aimed to determine the efficacy of pepsin-digested cashew proteins used as immunotherapy in a murine model of cashew allergy.

METHODS

Mice were sensitized to cashew and then underwent challenges with digested or native cashew allergens to assess the allergenicity of the protein preparations. Using native or pepsinized cashew proteins, mice underwent oral or intraperitoneal sensitization protocols to determine the immunogenic properties of the protein preparations. Finally, cashew-sensitized mice underwent an immunotherapy protocol with native or pepsinized cashew proteins and subsequent provocation challenges.

RESULTS

Pepsinized cashew proteins elicited weaker allergic reactions than native cashew proteins but importantly retained the ability to stimulate cellular proliferation and cytokine production. Mice sensitized with pepsinized proteins reacted on challenge with native allergens, demonstrating that pepsinized allergens retain immunogenicity in vivo. Immunotherapy with pepsinized cashew allergens significantly decreased allergic symptoms and body temperature decrease relative to placebo after challenge with native and pepsinized proteins. Immunologic changes were comparable after immunotherapy with native or pepsinized allergens: T(H)2-type cytokine secretion from splenocytes was decreased, whereas specific IgG(1) and IgG(2a) levels were increased.

CONCLUSIONS

Pepsinized cashew proteins are effective in treating cashew allergy in mice and appear to work through the same mechanisms as native protein immunotherapy.

The 2S albumin allergens of Arachis hypogaea, Ara h 2 and Ara h 6, are the major elicitors of anaphylaxis and can effectively desensitize peanut-allergic mice

BACKGROUND

Ara h 2 and Ara h 6, co-purified together in a 13-25 kD fraction (Ara h 2/6; 20 kD fraction) on gel filtration chromatography, account for the majority of effector activity in a crude peanut extract (CPE) when assayed with RBL SX-38 cells sensitized with IgE from human peanut allergic sera.

OBJECTIVES

To determine if Ara h 2/6 are the primary peanut allergens responsible for allergic reactions in vivo and to determine if Ara h 2/6 would be sufficient to prevent allergic reactions to a complete CPE.

METHODS

An oral sensitization mouse model of peanut allergy was used to assess the activity of Ara h 2/6 (20 kD) and CPE without the 20 kD fraction (CPE w/o 20 kD) for allergic provocation challenge and immunotherapy. The activity of these preparations was also tested in an assay of histamine release from human basophils in whole blood.

RESULTS

Compared with mice challenged with control CPE, mice challenged with CPE w/o 20 kD experienced reduced symptoms (P < 0.05) and a smaller decrease in body temperature (P < 0.01). Results with the basophil histamine release assay corroborated these findings (P < 0.01). The mouse model was also used to administer Ara h 2/6 (20 kD) in an immunotherapy protocol, in which peanut-allergic mice treated with the 20 kD fraction experienced significantly reduced symptoms, changes in body temperature, and mast cell protease (MMCP-1) release compared with placebo (P < 0.01 for all parameters). Importantly, immunotherapy with the 20 kD fraction was just as effective as treatment with CPE, whereas CPE w/o 20 kD was significantly less effective for higher dose peanut challenges.

CONCLUSIONS AND CLINICAL RELEVANCE

Ara h 2/6 are the most potent peanut allergens in vivo and can be used to desensitize peanut-allergic mice. These results have potential implications for clinical research in the areas of diagnosis and immunotherapy for peanut allergy.

Immunomodulatory gene therapy prevents antibody formation and lethal hypersensitivity reactions in murine pompe disease

Infantile Pompe disease progresses to a lethal cardiomyopathy in absence of effective treatment. Enzyme-replacement therapy (ERT) with recombinant human acid alpha-glucosidase (rhGAA) has been effective in most patients with Pompe disease, but efficacy was reduced by high-titer antibody responses. Immunomodulatory gene therapy with a low dose adeno-associated virus (AAV) vector (2 x 10(10) particles) containing a liver-specific regulatory cassette significantly lowered immunoglobin G (IgG), IgG1, and IgE antibodies to GAA in Pompe disease mice, when compared with mock-treated mice (P < 0.05). AAV-LSPhGAApA had the same effect on GAA-antibody production whether it was given prior to, following, or simultaneously with the initial GAA injection. Mice given AAV-LSPhGAApA had significantly less decrease in body temperature (P < 0.001) and lower anaphylactic scores (P < 0.01) following the GAA challenge. Mouse mast cell protease-1 (MMCP-1) followed the pattern associated with hypersensitivity reactions (P < 0.05). Regulatory T cells (Treg) were demonstrated to play a role in the tolerance induced by gene therapy as depletion of Treg led to an increase in GAA-specific IgG (P < 0.001). Treg depleted mice were challenged with GAA and had significantly stronger allergic reactions than mice given gene therapy without subsequent Treg depletion (temperature: P < 0.01; symptoms: P < 0.05). Ubiquitous GAA expression failed to prevent antibody formation. Thus, immunomodulatory gene therapy could provide adjunctive therapy in lysosomal storage disorders treated by enzyme replacement.