Evolutionary biology of plant food allergens

Solution structure, copper binding and backbone dynamics of recombinant Ber e 1-the major allergen from Brazil nut

BACKGROUND

The 2S albumin Ber e 1 is the major allergen in Brazil nuts. Previous findings indicated that the protein alone does not cause an allergenic response in mice, but the addition of components from a Brazil nut lipid fraction were required. Structural details of Ber e 1 may contribute to the understanding of the allergenic properties of the protein and its potential interaction partners.

METHODOLOGY/PRINCIPAL FINDINGS

The solution structure of recombinant Ber e 1 was solved using NMR spectroscopy and measurements of the protein back bone dynamics at a residue-specific level were extracted using (15)N-spin relaxation. A hydrophobic cavity was identified in the structure of Ber e 1. Using the paramagnetic relaxation enhancement property of Cu(2+) in conjunction with NMR, it was shown that Ber e 1 is able to specifically interact with the divalent copper ion and the binding site was modeled into the structure. The IgE binding region as well as the copper binding site show increased dynamics on both fast ps-ns timescale as well as slower µs-ms timescale.

CONCLUSIONS/SIGNIFICANCE

The overall fold of Ber e 1 is similar to other 2S albumins, but the hydrophobic cavity resembles that of a homologous non-specific lipid transfer protein. Ber e 1 is the first 2S albumin shown to interact with Cu(2+) ions. This Cu(2+) binding has minimal effect on the electrostatic potential on the surface of the protein, but the charge distribution within the hydrophobic cavity is significantly altered. As the hydrophobic cavity is likely to be involved in a putative lipid interaction the Cu(2+) can in turn affect the interaction that is essential to provoke an allergenic response.

Environmental effects on allergen levels in commercially grown non-genetically modified soybeans: assessing variation across north america

Soybean (Glycinemax) is a hugely valuable soft commodity that generates tens of billions of dollars annually. This value is due in part to the balanced composition of the seed which is roughly 1:2:2 oil, starch, and protein by weight. In turn, the seeds have many uses with various derivatives appearing broadly in processed food products. As is true with many edible seeds, soybeans contain proteins that are anti-nutritional factors and allergens. Soybean, along with milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, and wheat, elicit a majority of food allergy reactions in the United States. Soybean seed composition can be affected by breeding, and environmental conditions (e.g., temperature, moisture, insect/pathogen load, and/or soil nutrient levels). The objective of this study was to evaluate the influence of genotype and environment on allergen and anti-nutritional proteins in soybean. To address genetic and environmental effects, four varieties of non-GM soybeans were grown in six geographically distinct regions of North America (Georgia, Iowa, Kansas, Nebraska, Ontario, and Pennsylvania). Absolute quantification of proteins by mass spectrometry can be achieved with a technique called multiple reaction monitoring (MRM), during which signals from an endogenous protein are compared to those from a synthetic heavy-labeled internal standard. Using MRM, eight allergens were absolutely quantified for each variety in each environment. Statistical analyses show that for most allergens, the effects of environment far outweigh the differences between varieties brought about by breeding.

Food-induced anaphylaxis

Food-induced anaphylaxis (FIA) is a serious allergic reaction that may cause death rapidly in otherwise healthy individuals. There is no universal agreement on its definition or criteria for diagnosis. Hospital admissions for FIA have more than doubled in the last decade. Food is one of the most common causes of anaphylaxis, with most surveys indicating that food-induced reactions account for 30% to 50% of cases. The most commonly implicated foods are peanut, tree nuts, milk, eggs, sesame seeds, fish, and shellfish. The only life-saving treatment for anaphylaxis is allergen avoidance, and epinephrine injection if an anaphylactic event occurs.

Evolutionary history of the non-specific lipid transfer proteins

The non-specific lipid transfer proteins (nsLTPs) are small, basic proteins characterized by a tunnel-like hydrophobic cavity, capable of transferring various lipid molecules between lipid bilayers. Most nsLTPs are synthesized with an N-terminal signal peptide that localizes the protein to the apoplastic space. The nsLTPs have only been identified in seed plants, where they are encoded by large gene families. We have initiated an analysis of the evolutionary history of the nsLTP family using genomic and EST information from non-seed land plants and green algae to determine: (1) when the nsLTP family arose, (2) how often new nsLTP subfamilies have been created, and (3) how subfamilies differ in their patterns of expansion and loss in different plant lineages. In this study, we searched sequence databases and found that genes and transcripts encoding nsLTPs are abundant in liverworts, mosses, and all other investigated land plants, but not present in any algae. The tertiary structures of representative liverwort and moss nsLTPs were further studied with homology modeling. The results indicate that the nsLTP family has evolved after plants conquered land. Only two of the four major subfamilies of nsLTPs found in flowering plants are present in mosses and liverworts. The additional subfamilies have arisen later, during land plant evolution. In this report, we also introduce a modified nsLTP classification system.

Identification of major rice allergen and their clinical significance in children

Purpose

Recently, an increase in the number of patients sensitized to rice allergen with or without clinical symptoms has been reported. This study was designed to determine the major allergens in rice and their clinical significance.

Methods

Twenty-four children (15 boys and 9 girls; mean age, 16.3 months) with allergic disease, who were sensitized to rice antigen (by UniCAP) in the Pediatric Allergy Respiratory Center at Soonchunhyang University Hospital, were enrolled in this study. The allergenicity of various types of rice (raw, cooked, and heat-treated, simulated gastric fluid [SGF], and simulated intestinal fluid [SIF]) was investigated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoglobulin E (IgE) immunoblots. The patients' medical records, including laboratory data and allergy symptoms after ingestion of rice were reviewed.

Results

Patients were sensitized to an average of 13.5 food antigens and their mean total IgE was 6,888.7 kU/L. In SDS-PAGE, more than 16 protein bands were observed in the raw rice, whereas only 14-16 kDa and 31-35 kDa protein bands were observed in cooked rice. The common SDS-PAGE protein bands observed in SGF-, SIF-, and heat-treated rice were 9, 14, and 31 kDa. In a heated-rice IgE immunoblot, protein bands of 9, 14, and 31-33 kDa were found in 27.8%, 38.9%, and 38.9% of all sera, respectively, and in 50%, 50%, and 75%, of ser a from the 4 symptomatic patients, respectively.

Conclusion

The 9-, 14-, and 31-kDa protein bands appeared to be the major allergens responsible for rice allergy symptoms.

Kiwifruit Act d 11 is the first member of the ripening-related protein family identified as an allergen

BACKGROUND

Kiwifruit is an important cause of food allergy. A high amount of a protein with a molecular mass compatible with that of Bet v 1 was observed in the kiwifruit extract.

OBJECTIVE

To identify and characterize kirola, the 17-kDa protein of green kiwifruit (Act d 11).

METHODS

Act d 11 was purified from green kiwifruit. Its primary structure was obtained by direct protein sequencing. The IgE binding was investigated by skin testing, immunoblotting, inhibition tests, and detection by the ISAC microarray in an Italian cohort and in selected Bet v 1-sensitized Austrian patients. A clinical evaluation of kiwi allergy was carried out.

RESULTS

Act d 11 was identified as a member of the major latex protein/ripening-related protein (MLP/RRP) family. IgE binding to Act d 11 was shown by all the applied testing. Patients tested positive for Act d 11 and reporting symptoms on kiwifruit exposure were found within the Bet v 1-positive subset rather than within the population selected for highly reliable history of allergic reactions to kiwifruit. Epidemiology of Act d 11 IgE reactivity was documented in the two cohorts. IgE co-recognition of Act d 11 within the Bet v 1-like molecules is documented using the microarray IgE inhibition assay.

CONCLUSIONS

Act d 11 is the first member of the MLP/RRP protein family to be described as an allergen. It displays IgE co-recognition with allergens belonging to the PR-10 family, including Bet v 1.

Ara h 2: crystal structure and IgE binding distinguish two subpopulations of peanut allergic patients by epitope diversity

BACKGROUND

Peanut allergy affects 1% of the population and causes the most fatal food-related anaphylactic reactions. The protein Ara h 2 is the most potent peanut allergen recognized by 80-90% of peanut allergic patients.

METHODS

The crystal structure of the major peanut allergen Ara h 2 was determined for the first time at 2.7 Å resolution using a customized maltose-binding protein (MBP)-fusion system. IgE antibody binding to the MBP fusion construct vs the natural allergen was compared by ELISA using sera from peanut allergic patients.

RESULTS

The structure of Ara h 2 is a five-helix bundle held together by four disulfide bonds and related to the prolamin protein superfamily. The fold is most similar to other amylase and trypsin inhibitors. The MBP--Ara h 2 fusion construct was positively recognized by IgE from 76% of allergic patients (25/33). Two populations of patients could be identified. Subpopulation 1 (n = 14) showed an excellent correlation of IgE antibody binding to natural vs recombinant Ara h 2. Subpopulation 2 (n = 15) showed significantly reduced IgE binding to the MBP fusion protein. Interestingly, about 20% of the IgE binding in subpopulation 2 could be recovered by increasing the distance between MBP and Ara h 2 in a second construct.

DISCUSSION

The reduced IgE binding to the MBP--Ara h 2 of subpopulation 2 indicates that the MBP molecule protects an immunodominant epitope region near the first helix of Ara h 2. Residues involved in the epitope(s) are suggested by the crystal structure. The MBP--Ara h 2 fusion constructs will be useful to further elucidate the relevance of certain epitopes to peanut allergy.

The frontiers of mass spectrometry-based techniques in food allergenomics

In the last years proteomic science has started to provide an important contribution to the disclosure of basic aspects of food-related diseases. Among these, the identification of proteins involved in food allergy and their mechanism of activation of toxicity. Elucidation of these key issues requires the integration of clinical, immunological, genomic and proteomic approaches. These combined research efforts are aimed to obtain structural and functional information to assist the development of novel, more reliable and powerful diagnostic protocols alternative to the currently available procedures, mainly based on food challenge tests. Another crucial aspect related to food allergy is the need for methods to detect trace amounts of allergenic proteins in foods. Mass spectrometry is the only non-immunological method for high-specificity and high-sensitivity detection of allergens in foods. Nowadays, once provided the appropriate sample handling and the correct operative conditions, qualitative and quantitative determination of allergens in foods and ingredients can be efficiently obtained by MALDI-TOF-MS and LC-MS/MS methods, with limits of detection and quantification in the low-ppb range. The availability of accurate and fast alternatives to immunological ELISA tests may also enable the development of novel therapeutic strategies and food processing technologies to aid patients with food allergy or intolerance, and to support allergen labelling and certification processes, all issues where the role of proteomic science is emerging.

Specific conformational epitope features of pathogenesis-related proteins mediating cross-reactivity between pollen and food allergens

Selected members of plant pathogenesis-related and seed storage proteins represent specific groups of proteins with potential characteristics of allergens. Efforts to understand the mechanism by which pathogenesis-related proteins mediate a broad cross-reactivity in pollen-plant food allergens are still limited. In this study, computational biology approach was used to reveal specific structural implications and conservation of different epitopes from members of Bet v 1 and nsLTP protein families mediating cross-reactivity between pollen and food (fruits, vegetables, legumes, and nut/seeds) allergens. A commonly shared epitope conservation was found among all pollen and food Bet v 1 and nsLTP protein families, respectively. However, other allergenic epitopes were also specifically detected in each family. The implication of these conserved epitopes in a broad cross-reactivity for allergy clinical trials is here discussed.

A DIGE-based quantitative proteomic analysis of grape berry flesh development and ripening reveals key events in sugar and organic acid metabolism

Grapevine (Vitis vinifera L.) is an economically important fruit crop. Quality-determining grape components, such as sugars, acids, flavours, anthocyanins, tannins, etc., are accumulated during the different grape berry development stages. Thus, correlating the proteomic profiles with the biochemical and physiological changes occurring in grape is of paramount importance to advance the understanding of the berry development and ripening processes. Here, the developmental analysis of V. vinifera cv. Muscat Hamburg berries is reported at protein level, from fruit set to full ripening. A top-down proteomic approach based on differential in-gel electrophoresis (DIGE) followed by tandem mass spectrometry led to identification and quantification of 156 and 61 differentially expressed proteins in green and ripening phases, respectively. Two key points in development, with respect to changes in protein level, were detected: end of green development and beginning of ripening. The profiles of carbohydrate metabolism enzymes were consistent with a net conversion of sucrose to malate during green development. Pyrophosphate-dependent phosphofructokinase is likely to play a key role to allow an unrestricted carbon flow. The well-known change of imported sucrose fate at the beginning of ripening from accumulation of organic acid (malate) to hexoses (glucose and fructose) was well correlated with a switch in abundance between sucrose synthase and soluble acid invertase. The role of the identified proteins is discussed in relation to their biological function, grape berry development, and to quality traits. Another DIGE experiment comparing fully ripe berries from two vintages showed very few spots changing, thus indicating that protein changes detected throughout development are specific.

Comparative analysis of expressed sequence tags (ESTs) between drought-tolerant and -susceptible genotypes of chickpea under terminal drought stress

BACKGROUND

Chickpea (Cicer arietinum L.) is an important grain-legume crop that is mainly grown in rainfed areas, where terminal drought is a major constraint to its productivity. We generated expressed sequence tags (ESTs) by suppression subtraction hybridization (SSH) to identify differentially expressed genes in drought-tolerant and -susceptible genotypes in chickpea.

RESULTS

EST libraries were generated by SSH from root and shoot tissues of IC4958 (drought tolerant) and ICC 1882 (drought resistant) exposed to terminal drought conditions by the dry down method. SSH libraries were also constructed by using 2 sets of bulks prepared from the RNA of root tissues from selected recombinant inbred lines (RILs) (10 each) for the extreme high and low root biomass phenotype. A total of 3062 unigenes (638 contigs and 2424 singletons), 51.4% of which were novel in chickpea, were derived by cluster assembly and sequence alignment of 5949 ESTs. Only 2185 (71%) unigenes showed significant BLASTX similarity (<1E-06) in the NCBI non-redundant (nr) database. Gene ontology functional classification terms (BLASTX results and GO term), were retrieved for 2006 (92.0%) sequences, and 656 sequences were further annotated with 812 Enzyme Commission (EC) codes and were mapped to 108 different KEGG pathways. In addition, expression status of 830 unigenes in response to terminal drought stress was evaluated using macro-array (dot blots). The expression of few selected genes was validated by northern blotting and quantitative real-time PCR assay.

CONCLUSION

Our study compares not only genes that are up- and down-regulated in a drought-tolerant genotype under terminal drought stress and a drought susceptible genotype but also between the bulks of the selected RILs exhibiting extreme phenotypes. More than 50% of the genes identified have been shown to be associated with drought stress in chickpea for the first time. This study not only serves as resource for marker discovery, but can provide a better insight into the selection of candidate genes (both up- and downregulated) associated with drought tolerance. These results can be used to identify suitable targets for manipulating the drought-tolerance trait in chickpea.

Anti-acid medication as a risk factor for food allergy

An important feature for oral allergens is their digestion-resistance during gastrointestinal transit. For some oral allergens, digestion stability is an innate feature, whereas digestion-labile antigens may only persist in times of impairment of the digestive system. In this review, we collect evidence from mouse and human studies that besides the inherent molecular characteristics of a food protein, the stomach function is decisive for the allergenic potential. Gastric acid levels determine the activation of gastric pepsin and also the release of pancreatic enzymes. When anti-ulcer drugs inhibit or neutralize gastric acid, they allow persistence of intact food allergens and protein-bound oral drugs with enhanced capacity to sensitize and elicit allergic reactions via the oral route. Mouse studies further suggest that maternal food allergy arising from co-application of a food protein with anti-acid drugs results in a Th2-biased immune response in the offspring. Especially, anti-ulcer drugs containing aluminum compounds act as Th2 adjuvants. Proton pump inhibitors act on proton secretion but also on expression of the morphogen Sonic hedgehog, which has been related to the development of atrophic gastritis. On the other hand, atrophic gastritis and resulting hypoacidity have previously been correlated with enhanced sensitization risk to food allergens in elderly patients. In summary, impairment of gastric function is a documented risk factor for sensitization against oral proteins and drugs.

Bet v 1 and its homologous food allergen Api g 1 stimulate dendritic cells from birch pollen-allergic individuals to induce different Th-cell polarization

BACKGROUND

Bet v 1 is the most relevant sensitizing protein for birch pollen (BP)-allergic individuals. Its homologues from plant foods are mainly involved in allergic reactions caused by IgE cross reactivity. We aimed to evaluate the polarizing effect of dendritic cells (DCs) pulsed with Bet v 1, Mal d 1, Api g 1 or Dau c 1 on Th-cell responses.

METHODS

Immature DCs were generated from peripheral blood monocytes of BP-allergic and healthy donors by culture with GM-CSF and IL-4 and subsequently pulsed with allergens in combination with maturation factors. Cell surface markers were analysed by FACS. Mature DCs were co-cultured with autologous Th cells and T-cell proliferation and cytokine profiles were determined.

RESULTS

In co-culture, mature allergen-pulsed DCs induced autologous Th cells of BP-allergic donors to proliferate significantly more than those of healthy individuals. Exposure of DCs from BP-allergic donors to Bet v 1 resulted in a robust Th2 skewing with significantly higher quantities of IL-5 and elevated IL-13 compared to maturation factors. In contrast, Api g 1-primed DCs from BP allergics significantly enhanced the production of the Th1 cytokine IFN-γ and significantly down-regulated IL-13 compared to maturation factors. In healthy donors, no significant cytokine production could be detected.

CONCLUSION

Bet v 1 in contrast to homologous food allergens seems to possess distinct molecular features that enable it to condition DCs from BP-allergic donors to induce allergen-specific T-cell proliferation and Th2 polarization.

Identification of Bet v 1-related allergens in fig and other Moraceae fruits

BACKGROUND

Allergy to fig fruit (Ficus carica) has been described in patients allergic to Ficus benjamina or rubber latex but may occur also in pollen-allergic patients.

OBJECTIVE

To study the potential cross-reactivity between fig and taxonomically related fruits with the major birch pollen allergen Bet v 1.

METHODS

One hundred and eighty-eight patients with or without birch pollen allergy were prick-to-prick tested with fig (F. carica), mulberry (Morus alba), jackfruit (Artocarpus heterophyllus; all family Moraceae) and other pollen-associated foods. Moraceae fruit extracts were separated by SDS-PAGE and tested with patient sera and polyclonal antisera against Mal d 1. Western blot inhibition was performed with Moraceae fruit extracts, birch pollen and recombinant Bet v 1. Putative Bet v 1 homologs in Moraceae fruits were analysed by liquid chromatography-ion trap mass spectrometry.

RESULTS

Among 85 patients with isolated birch pollen allergy, 78% had a positive skin test to fresh fig, 10% to dried fig, 91% to mulberry, 91% to jackfruit, 77% to Rosaceae fruits and 83% to hazelnut. Sixty-six per cent of birch pollen-allergic patients positive for fig, reported symptoms after consumption of fresh figs, whereas dried figs were mostly well tolerated. In 60 patients with isolated Ficus benjamina sensitization, the reactivity rates to the same foods were 83-40-0-0-0-0%. None of 32 mugwort pollen-allergic patients reacted to Moraceae fruits. Rabbit anti-Mal d 1 and patient sera reacted to a 17 kDa band in all Moraceae extracts. IgE binding to these proteins was completely inhibited by birch pollen and rBet v 1. Mass spectrometry identified several peptides from the 17 kDa fig, mulberry and jackfruit allergen with respectively 60%, 56% and 76% homology to Bet v 1.

CONCLUSION

Fig and other Moraceae fruits contain allergens homologous to Bet v 1 and represent clinically relevant birch pollen-associated foods.

A new allergen from ragweed (Ambrosia artemisiifolia) with homology to art v 1 from mugwort

Art v 1, the major pollen allergen of the composite plant mugwort (Artemisia vulgaris) has been identified recently as a thionin-like protein with a bulky arabinogalactan-protein moiety. A close relative of mugwort, ragweed (Ambrosia artemisiifolia) is an important allergen source in North America, and, since 1990, ragweed has become a growing health concern in Europe as well. Weed pollen-sensitized patients demonstrated IgE reactivity to a ragweed pollen protein of apparently 29-31 kDa. This reaction could be inhibited by the mugwort allergen Art v 1. The purified ragweed pollen protein consisted of a 57-amino acid-long defensin-like domain with high homology to Art v 1 and a C-terminal proline-rich domain. This part contained hydroxyproline-linked arabinogalactan chains with one galactose and 5 to 20 and more alpha-arabinofuranosyl residues with some beta-arabinoses in terminal positions as revealed by high field NMR. The ragweed protein contained only small amounts of the single hydroxyproline-linked beta-arabinosyl residues, which form an important IgE binding determinant in Art v 1. cDNA clones for this protein were obtained from ragweed flowers. Immunological characterization revealed that the recombinant ragweed protein reacted with >30% of the weed pollen allergic patients. Therefore, this protein from ragweed pollen constitutes a novel important ragweed allergen and has been designated Amb a 4.

The strawberry fruit Fra a allergen functions in flavonoid biosynthesis

The strawberry Fra a 1 allergen is a homolog of the major birch pollen allergen Bet v 1. It is synthesized by red ripe fruits of Fragaria x ananassa while white fruits of a mutant genotype, which is known to be tolerated by individuals affected by allergy, are devoid of it. Proteomic analyses have shown that Fra a 1 is down-regulated in the tolerated white-fruited genotype along with enzymes of the anthocyanin pigment pathway. In this study, we report the spatial and temporal expression of three Fra a genes that encode different isoforms, and the transient RNAi-mediated silencing of the Fra a genes in strawberry fruits of the red-fruited cultivar Elsanta with an ihpRNA construct. As a consequence of reduced levels of Fra a mRNAs, fruits were obtained that produced significantly decreased levels of anthocyanins and upstream metabolites. This effect is consistent with the parallel down-regulation of the phenylalanine ammonia lyase (FaPAL) and to a lesser extent of the chalcone synthase (FaCHS) transcript levels also found in these fruits. In naturally occurring white-fruited genotypes of F. chiloensis and F. vesca, Fra a transcript levels are higher than those of the red-fruited varieties, likely to compensate for the low expression levels of FaPAL and FaCHS in these mutant genotypes. The results demonstrate that Fra a expression is directly linked to flavonoid biosynthesis and show that the Fra a allergen has an essential biological function in pigment formation in strawberry fruit.

Food allergy

Adverse immune responses to foods affect approximately 5% of young children and 3% to 4% of adults in westernized countries and appear to have increased in prevalence. Food-induced allergic reactions are responsible for a variety of symptoms and disorders involving the skin and gastrointestinal and respiratory tracts and can be attributed to IgE-mediated and non-IgE-mediated (cellular) mechanisms. Genetic disposition and environmental factors might abrogate oral tolerance, leading to food allergy. Disease outcomes are influenced by the characteristics of the immune response and of the triggering allergen. Diagnosis is complicated by the observation that detection of food-specific IgE (sensitization) does not necessarily indicate clinical allergy. Therefore diagnosis requires a careful medical history, laboratory studies, and, in many cases, an oral food challenge to confirm a diagnosis. Novel diagnostic methods, including ones that focus on immune responses to specific food proteins or epitopes of specific proteins, are under study. Currently, management of food allergies consists of educating the patient to avoid ingesting the responsible allergen and to initiate therapy (eg, with injected epinephrine for anaphylaxis) in case of an unintended ingestion. Improved therapeutic strategies under study include oral and sublingual immunotherapy, Chinese herbal medicine, anti-IgE antibodies, and modified vaccines.

Novel IgE recognized components of Lolium perenne pollen extract: comparative proteomics evaluation of allergic patients sensitization profiles

In the last years, proteomic investigation provided a powerful tool in molecular characterization of complex allergen sources with relevant implications in both diagnosis and immunotherapic treatment of allergies. We followed a proteomic approach to characterize ryegrass (Lolium perenne) pollen, a common cause of seasonal allergic diseases affecting an increasing part of world population. Peptide shotgun experiments performed on nanoLiquid Ultra Pressure Chromatography coupled with fast Q-TOF MS-MS/MS acquisition protocols (MS(E)) and 2-DE immunoblot combined with MALDI-TOF-TOF analysis allowed the detection of all previously identified ryegrass allergens. Comparative analysis of immunoblot highlighted a class of patients characterized by a more complex 2-DE pattern associated with increased levels of IgE antibodies and by higher susceptibility to multiple sensitization toward different allergen sources. Cluster analysis revealed that all these patients recognized profilin, considered the main cross-reactive allergen in grass pollen. Furthermore, mass spectrometry analysis revealed the presence of other IgE reactive components in ryegrass pollen that might be involved in polysensitization, such as cyclophilin, fructosyltransferase and legumin-like protein.

14-Day Repeat-Dose Oral Toxicity Evaluation of Oxazyme in Rats and Dogs

Oxazyme (OC4) is an orally administered formulation that has as an active component a recombinant mutant form of Bacillus subtilis oxalate decarboxylase (OxDC) enzyme C383S, designed to degrade dietary oxalate in the stomach. Fourteen-day repeat-dose studies were conducted in rats and dogs to evaluate toxicity and determine a no observed adverse effect level (NOAEL). Animals were administered OC4 by oral gavage twice daily for 14 consecutive days. Reversibility, progression, and delayed appearance of any observed changes were evaluated in a subset of animals that underwent a recovery of 7 days following 14 days of control or test-article. There were no test-article-related adverse effects or deaths in either species. Results indicate that the NOAEL under the conditions used in the studies was 720.8 mg/kg/d in rats and 187.2 mg/kg/d in dogs, the high dose tested in each species.

Food allergy: review, classification and diagnosis

Food allergies, defined as an immune response to food proteins, affect as many as 8% of young children and 2% of adults in westernized countries, and their prevalence appears to be rising like all allergic diseases. In addition to well-recognized urticaria and anaphylaxis triggered by IgE antibody-mediated immune responses, there is an increasing recognition of cell-mediated disorders such as eosinophilic esophagitis and food protein-induced enterocolitis. New knowledge is being developed on the pathogenesis of both IgE and non-IgE mediated disease. Currently, management of food allergies consists of educating the patient to avoid ingesting the responsible allergen and initiating therapy if ingestion occurs. However, novel strategies are being studied, including sublingual/oral immunotherapy and others with a hope for future.

Molecular cloning, mass spectrometric identification, and nutritional evaluation of 10 coixins in adlay ( Coix lachryma-jobi L.)

Adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) is regarded as a nutritive food source as well as herbal medicine. The food nutrition is a consequence of its high protein content and superior amino acid composition. From ca. 200 expressed sequence tag (EST) sequences in maturing adlay grains, clones encoding precursor polypeptides of 10 seed storage proteins in the prolamin family, including 8 alpha-coixin isoforms, 1 delta-coixin, and 1 gamma-coixin, were identified. Full-length cDNA fragments encoding these 10 coixins were obtained by PCR cloning. Mass spectrometric analyses confirmed the presence of these 10 coixins in the extract of adlay grain. Calculated amino acid compositions indicate that all 10 coixins are rich in glutamine (>20% in alpha-coixin isoforms, 13.3% in delta-coixin, and 31.2% in gamma-coixin). The 8 alpha-coixin isoforms are low in methionine, cysteine, and lysine (on average, 0.8, 0.6, and 0.1%, respectively). However, the delta-coixin is a sulfur-rich protein (18.2% methionine and 9.1% cysteine), and the gamma-coixin is a nutritive protein composed of 2.0% methionine, 6.6% cysteine, 2.6% lysine, and 8.9% histidine. The company of delta-coixin and gamma-coixin with alpha-coixin isoforms enhances the nutritional value of alday grain for human consumption.

Food allergy: recent advances in pathophysiology and treatment

Food allergies, defined as an adverse immune response to food proteins, affect as many as 6% of young children and 3%-4% of adults in westernized countries, and their prevalence appears to be rising. In addition to well-recognized acute allergic reactions and anaphylaxis triggered by IgE antibody-mediated immune responses to food proteins, there is an increasing recognition of cell-mediated disorders such as eosinophilic gastroenteropathies and food protein-induced enterocolitis syndrome. We are gaining an increasing understanding of the pathophysiology of food allergic disorders and are beginning to comprehend how these result from a failure to establish or maintain normal oral tolerance. Many food allergens have been characterized at a molecular level, and this knowledge, combined with an increasing appreciation of the nature of humoral and cellular immune responses resulting in allergy or tolerance, is leading to novel therapeutic approaches. Currently, management of food allergies consists of educating the patient to avoid ingesting the responsible allergen and initiating therapy if ingestion occurs. However, numerous strategies for definitive treatment are being studied, including sublingual/oral immunotherapy, injection of anti-IgE antibodies, cytokine/anticytokine therapies, Chinese herbal therapies, and novel immunotherapies utilizing engineered proteins and strategic immunomodulators.

Isolation and expression analysis of a novel major latex-like protein (MLP151) gene from Panax ginseng

This is the first reports on isolation and expression analysis of a major latex-like protein (MLP151) gene in Panax ginseng C.A. Meyer. A full-length cDNA of MLP151 was 850 bp and contained a 456 bp open reading frame encoding a polypeptide of 151 amino acids. A theoretical pI value of MLP151 was 4.86 and calculated molecular weight was about 16.87 kDa. The MLP homolog proteins are found in various plants and the neighbor-joining analysis revealed that MLP151 has the closest distance with Sn-1 (bell pepper, MLP homolog gene). We analyzed the expression of MLP151 in different levels in various organs of ginseng and plantlet. In the result, the gene was low expressed in plantlet. We treated the ginseng plantlets with nine kinds of different stresses and analyzed the expression profile of MLP151. Transcript levels were significantly induced by stress treatment of light and mannitol, whereas transcript levels were drastically decreased in dark, H(2)O(2), salicylic acid and wounding samples.

A not so healthy muesli: a case report

We present a patient with severe anaphylaxis, angioedema, hypotension and shock. The near fatal allergic reaction was caused by eating yogurt with muesli containing pine nuts. The patient developed an acute infero-posterolateral myocardial infarction due to systemic hypotension and shock. Food allergy to pine nut was demonstrated by dosage of specific IgE to pine nut.

Partial Characterization of a Vicilin-Like Glycoprotein from Seeds of Flowering Tobacco (Nicotiana sylvestris)

A vicilin-like glycoprotein from the seeds of Nicotiana sylvestris, flowering tobacco, has been identified using nanoLC/ESI-MS/MS. Sequences from a fragment of protein demonstrated homology with vicilins from other members of the Solanaceae family, notably potato (Solanum demissum). Reducing and nonreducing SDS-PAGE analyses of the identified protein indicated that fragments resulting from in situ proteolytic processing are joined by intrachain disulphide bonds. Staining with Con A lectin was specifically inhibited by mannose suggested the presence of -linked glycosylation which was confirmed by carbohydrate compositional analysis of PVDF-bound protein subunits. HPAEC-PAD analysis of the monosaccharides released from the glycoprotein by acid hydrolysis revealed glucosamine and mannose. -acetylglucosamine termination of attached oligosaccharides was further verified by inhibitable WGA lectin staining. Immunostaining of PVDF-bound N. sylvestris proteins with antibodies against G. max total protein demonstrated cross-staining at masses corresponding to fragments from the proteolytically processed protein subunits.

Peach ( Prunus persica L. Batsch) allergen-encoding genes are developmentally regulated and affected by fruit load and light radiation

The fruits of Rosaceae species may frequently induce allergic reactions in both adults and children, especially in the Mediterranean area. In peach, true allergens and cross-reactive proteins may cause hypersensitive reactions involving a wide diversity of symptoms. Three known classes of allergenic proteins, namely, Pru p 1, Pru p 3, and Pru p 4, have been reported to be mostly involved, but an exhaustive survey of the proteins determining the overall allergenic potential, their biological functions, and the factors affecting the expression of the related genes is still missing. In the present study, the expression profiles of some selected genes encoding peach allergen isoforms were studied during fruit growth and development and upon different fruit load and light radiation regimens. The results indicate that the majority of allergen-encoding genes are expressed at their maximum during the ripening stage, therefore representing a potential risk for peach consumers. Nevertheless, enhancing the light radiation and decreasing the fruit load achieved a reduction of the transcription rate of most genes and a possible decrease of the overall allergenic potential at harvest. According to these data, new growing practices could be set up to obtain hypoallergenic peach fruits and eventually combined with the cultivation of hypoallergenic genotypes to obtain a significant reduction of the allergenic potential.

Allergen structures and biologic functions: the cutting edge of allergy research

Studies of structure and function of allergens using state-of-the-art technologies have led to a better understanding of allergenicity, including aspects related to cross-reactivity, allergen nomenclature, and the identification of antigenic determinants. This information is being applied to the design and production of allergy vaccines, some of which already have proven efficacy and safety in clinical trials.

The Bet v 1 fold: an ancient, versatile scaffold for binding of large, hydrophobic ligands

Background

The major birch pollen allergen, Bet v 1, is a member of the ubiquitous PR-10 family of plant pathogenesis-related proteins. In recent years, a number of diverse plant proteins with low sequence similarity to Bet v 1 was identified. In addition, determination of the Bet v 1 structure revealed the existence of a large superfamily of structurally related proteins. In this study, we aimed to identify and classify all Bet v 1-related structures from the Protein Data Bank and all Bet v 1-related sequences from the Uniprot database.

Results

Structural comparisons of representative members of already known protein families structurally related to Bet v 1 with all entries of the Protein Data Bank yielded 47 structures with non-identical sequences. They were classified into eleven families, five of which were newly identified and not included in the Structural Classification of Proteins database release 1.71. The taxonomic distribution of these families extracted from the Pfam protein family database showed that members of the polyketide cyclase family and the activator of Hsp90 ATPase homologue 1 family were distributed among all three superkingdoms, while members of some bacterial families were confined to a small number of species. Comparison of ligand binding activities of Bet v 1-like superfamily members revealed that their functions were related to binding and metabolism of large, hydrophobic compounds such as lipids, hormones, and antibiotics. Phylogenetic relationships within the Bet v 1 family, defined as the group of proteins with significant sequence similarity to Bet v 1, were determined by aligning 264 Bet v 1-related sequences. A distance-based phylogenetic tree yielded a classification into 11 subfamilies, nine exclusively containing plant sequences and two subfamilies of bacterial proteins. Plant sequences included the pathogenesis-related proteins 10, the major latex proteins/ripening-related proteins subfamily, and polyketide cyclase-like sequences.

Conclusion

The ubiquitous distribution of Bet v 1-related proteins among all superkingdoms suggests that a Bet v 1-like protein was already present in the last universal common ancestor. During evolution, this protein diversified into numerous families with low sequence similarity but with a common fold that succeeded as a versatile scaffold for binding of bulky ligands.

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

BACKGROUND

Examination of IgE cross-reactivity among nuts has been limited to in vitro experiments. Cross-reactivity studies of nuts at the T cell level are difficult to interpret because of the inability to determine which cellular responses are from a true sensitization and which are due to cross-reactivity. Using a mouse model in which the sensitizing nuts are controlled may provide novel methods to investigate in vivo and T cell cross-reactivity.

METHODS

C3H/HeJ mice were sensitized by intraperitoneal injection of cashew alone (monosensitized mice), or cashew plus walnut, utilizing alum as an adjuvant. Both groups underwent challenges to cashew, walnut and peanut, with subsequent monitoring of anaphylactic reactions. Anaphylactic antibodies were quantified by ELISA, and protein allergens were identified by Western blotting. Cellular responses were studied via splenocyte proliferation assay and measurement of secreted cytokines.

RESULTS

The monosensitized mice reacted to cashew and walnut during challenges, with significantly weaker reactions induced on challenge with peanut. Cross-reactive IgE to walnut and peanut were detected by ELISA, and the cross-reactive allergens were identified as vicilin proteins. In cellular assays, splenocytes from the monosensitized mice proliferated and produced IL-4 and IL-5 in response to cashew, walnut and peanut. The cashew- plus walnut-sensitized mice experienced stronger clinical reactions to walnut, recognized additional walnut allergens and secreted significantly more IL-4 and IL-5 in walnut-stimulated splenocyte assays compared to the monosensitized mice.

CONCLUSIONS

Cross-reactivity in vivo was found between cashew and walnut, while cross-reactivity among cashew, walnut and peanut was demonstrated at the T cell level.

Allergens are distributed into few protein families and possess a restricted number of biochemical functions

BACKGROUND

Existing allergen databases classify their entries by source and route of exposure, thus lacking an evolutionary, structural, and functional classification of allergens.

OBJECTIVE

We sought to build AllFam, a database of allergen families, and use it to extract common structural and functional properties of allergens.

METHODS

Allergen data from the Allergome database and protein family definitions from the Pfam database were merged into AllFam, a database that is freely accessible on the Internet at http://www.meduniwien.ac.at/allergens/allfam/. A structural classification of allergens was established by matching Pfam families with families from the Structural Classification of Proteins database. Biochemical functions of allergens were extracted from the Gene Ontology Annotation database.

RESULTS

Seven hundred seven allergens were classified by sequence into 134 AllFam families containing 184 Pfam domains (2% of 9318 Pfam families). A random set of 707 sequences with the same taxonomic distribution contained a significantly higher number of different Pfam domains (479 +/- 17). Classifying allergens by structure revealed that 5% of 3012 Structural Classification of Proteins families contained allergens. The biochemical functions of allergens most frequently found were limited to hydrolysis of proteins, polysaccharides, and lipids; binding of metal ions and lipids; storage; and cytoskeleton association.

CONCLUSION

The small number of protein families that contain allergens and the narrow functional distribution of most allergens confirm the existence of yet unknown factors that render proteins allergenic.

Factors predicting anaphylaxis to peanuts and tree nuts in patients referred to a specialist center

BACKGROUND

Although acute allergic reactions after ingestion of peanuts and tree nuts are common, fatalities are rare. Other than patients with coexisting asthma, it is currently not possible to predict which patients are most likely to develop severe reactions.

OBJECTIVE

The aim of this study was to determine which clinical and laboratory parameters best predict the likelihood of severe allergic reactions.

METHODS

From 1992 to 2004, we collected detailed information on the clinical severity and allergy test results of 1094 patients with peanut and tree nut allergy attending a regional allergy center. In a subgroup of 122 patients, sera were assayed for activity of enzymes involved in the catabolism of bradykinin.

RESULTS

Severe pharyngeal edema was 3.8 (2.1-6.9) times more common in patients with severe rhinitis and 2.6 (1.8-3.7) more common after ingestion of tree nuts compared with peanuts. Patients with serum angiotensin-converting enzyme concentrations <37.0 mmol/L had a 9.6 (1.6-57)-fold risk of severe pharyngeal edema. Life-threatening bronchospasm was most likely in patients with severe asthma (relative risk, 6.8 [4.1-11.3]) and less so in patients with milder asthma (2.7 [1.7-4.0]). Altered levels of consciousness were more likely in patients with severe eczema (3.1 [1.1-8.4]).

CONCLUSION

Severity of coexisting atopic diseases predicted which patients attending a tertiary referral clinic were most likely to develop life-threatening allergic reactions to peanuts and tree nuts. Patients with the lowest serum angiotensin-converting enzyme concentrations were more likely to develop life-threatening pharyngeal edema, suggesting that this complication may be partly mediated by bradykinin.