Wheat and barley allergens associated with baker's asthma. Glycosylated subunits of the alpha-amylase-inhibitor family have enhanced IgE-binding capacity.
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ABSTRACT:
SUBMITTER: Sanchez-Monge R
PROVIDER: S-EPMC1130698 | biostudies-other | 1992 Jan
REPOSITORIES: biostudies-other
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Project description:Baker's asthma, a typical occupational allergic disease, is a serious problem in the food industries. In this study, purification and identification of major allergens recognized by IgEs in sera of allergic patients were performed. Major immunoreactive proteins were purified from the albumin fraction by gel filtration on a Toyopearl HW-50 column followed by reverse-phase HPLC. The N-terminal amino acid sequences and molecular masses measured by MS indicated that the major immunoreactive proteins are members of the alpha-amylase inhibitor family, 0.19 and 0.28. Significant leukotriene release by each purified protein was observed in cell-associated stimulation tests, suggesting in vivo activity of these antigens. Carbohydrate analyses of major allergens indicated that they are monoglycosylated but not N-glycosylated in spite of the presence of a potential N-glycosylation site. Recombinant 0.19 expressed in Escherichia coli showed the same reactivity with IgE as native wheat 0.19 in Western blotting and ELISA using methyl vinyl ether maleic anhydride co-polymer as an immobilizing reagent, suggesting that the allergenic epitopes are located in the peptide portions.
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Project description:Allergic asthma is characterized by airway hyperresponsiveness, inflammation, and a cellular infiltrate dominated by eosinophils. Numerous epidemiological studies have related the exacerbation of allergic asthma with an increase in ambient inhalable particulate matter from air pollutants. This is because inhalable particles efficiently deliver airborne allergens deep into the airways, where they can aggravate allergic asthma symptoms. However, the cellular mechanisms by which inhalable particulate allergens (pAgs) potentiate asthmatic symptoms remain unknown, in part because most in vivo and in vitro studies exploring the pathogenesis of allergic asthma use soluble allergens (sAgs). Using a mouse model of allergic asthma, we found that, compared with their sAg counterparts, pAgs triggered markedly heightened airway hyperresponsiveness and pulmonary eosinophilia in allergen-sensitized mice. Mast cells (MCs) were implicated in this divergent response, as the differences in airway inflammatory responses provoked by the physical nature of the allergens were attenuated in MC-deficient mice. The pAgs were found to mediate MC-dependent responses by enhancing retention of pAg/IgE/Fc?RI complexes within lipid raft–enriched, CD63(+) endocytic compartments, which prolonged IgE/Fc?RI-initiated signaling and resulted in heightened cytokine responses. These results reveal how the physical attributes of allergens can co-opt MC endocytic circuitry and signaling responses to aggravate pathological responses of allergic asthma in mice.
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Project description: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.
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Project description:Food-processing conditions may alter the allergenicity of food proteins by different means. In this study, the effect of the glycosylation as a result of thermal treatment on the digestibility and IgE-binding of codfish parvalbumin is investigated. Native and glycosylated parvalbumins were digested with pepsin at various conditions relevant for the gastrointestinal tract. Intact proteins and peptides were analysed for apparent molecular weight and IgE-binding. Glycosylation did not substantially affect the digestion. Although the peptides resulting from digestion were relatively large (3 and 4 kDa), the IgE-binding was strongly diminished. However, the glycosylated parvalbumin had a strong propensity to form dimers and tetramers, and these multimers bound IgE intensely, suggesting stronger IgE-binding than monomeric parvalbumin. We conclude that glycosylation of codfish parvalbumin does not affect the digestibility of parvalbumin and that the peptides resulting from this digestion show low IgE-binding, regardless of glycosylation. Glycosylation of parvalbumin leads to the formation of higher order structures that are more potent IgE binders than native, monomeric parvalbumin. Therefore, food-processing conditions applied to fish allergen can potentially lead to increased allergenicity, even while the protein's digestibility is not affected by such processing.
| S-EPMC3708386 | biostudies-literature
Project description:Barley is an important crop for the production of malt and beer. However, crops such as rice and wheat are rarely used for malting. α-amylase is the key enzyme that degrades starch during malting. In this study, we compared the genomic properties, gene copies, and conserved promoter motifs of α-amylase genes in barley, rice, and wheat. In all three crops, α-amylase consists of four subfamilies designated amy1, amy2, amy3, and amy4. In wheat and barley, members of amy1 and amy2 genes are localized on chromosomes 6 and 7, respectively. In rice, members of amy1 genes are found on chromosomes 1 and 2, and amy2 genes on chromosome 6. The barley genome has six amy1 members and three amy2 members. The wheat B genome contains four amy1 members and three amy2 members, while the rice genome has three amy1 members and one amy2 member. The B genome has mostly amy1 and amy2 members among the three wheat genomes. Amy1 promoters from all three crop genomes contain a GA-responsive complex consisting of a GA-responsive element (CAATAAA), pyrimidine box (CCTTTT) and TATCCAT/C box. This study has shown that amy1 and amy2 from both wheat and barley have similar genomic properties, including exon/intron structures and GA-responsive elements on promoters, but these differ in rice. Like barley, wheat should have sufficient amy activity to degrade starch completely during malting. Other factors, such as high protein with haze issues and the lack of husk causing Lauting difficulty, may limit the use of wheat for brewing.
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Project description:BackgroundThe specificities of IgE and IgG for allergen molecules in patients with inborn errors of immunity (IEI) have not been investigated in detail.ObjectiveTo study IgE and IgG antibody specificities in patients with defined hyper-IgE syndromes (HIES) using a comprehensive panel of allergen molecules.MethodsWe used chips containing micro-arrayed allergen molecules to analyze allergen-specific IgE and IgG levels in sera from two groups of HIES patients: Autosomal recessive mutations in phosphoglucomutase-3 (PGM3); Autosomal dominant negative mutations of STAT3 (STAT3); and age-matched subjects with allergic sensitizations. Assays with rat basophil leukemia cells transfected with human FcεRI were performed to study the biological relevance of IgE sensitizations.ResultsMedian total IgE levels were significantly lower in the sensitized control group (212.9 kU/L) as compared to PGM3 (5042 kU/L) and STAT3 patients (2561 kU/L). However, PGM3 patients had significantly higher allergen-specific IgE levels and were sensitized to a larger number of allergen molecules as compared to STAT3 patients. Biological relevance of IgE sensitization was confirmed for PGM3 patients by basophil activation testing. PGM3 patients showed significantly lower cumulative allergen-specific IgG responses in particular to milk and egg allergens as compared to STAT3 patients and sensitized controls whereas total IgG levels were comparable to STAT3 patients and significantly higher than in controls.ConclusionThe analysis with multiple micro-arrayed allergen molecules reveals profound differences of allergen-specific IgE and IgG recognition in PGM3 and STAT3 patients which may be useful for classification of IEI and clinical characterization of patients.
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Project description:Serpin protease inhibitors and ?-amylase starch hydrolases are very abundant seed proteins in the endosperm of grasses. ?-amylase is a crucial enzyme in the beer industry providing maltose for fermenting yeast. In animals and plants, inhibitory serpins form covalent linkages that inactivate their cognate proteases. Additionally, in animals, noninhibitory functions for serpins are observed such as metabolite carriers and chaperones. The function of serpins in seeds has yet to be unveiled. In developing endosperm, serpin Z4 and ?-amylase showed similar in vivo spatio-temporal accumulation properties and colocalize in the cytosol of transformed tobacco leaves. A molecular interaction between recombinant proteins of serpin Z4 and ?-amylase was revealed by surface plasmon resonance and microscale thermophoresis yielding a dissociation constant of 10-7 M. Importantly, the addition of serpin Z4 significantly changes ?-amylase enzymatic properties by increasing its maximal catalytic velocity. The presence of serpin Z4 stabilizes ?-amylase activity during heat treatment without affecting its critical denaturing temperature. Oxidative stress, simulated by the addition of CuCl2, leads to the formation of high molecular weight polymers of ?-amylase similar to those detected in vivo. The polymers were cross-linked through disulfide bonds, the formation of which was repressed when serpin Z4 was present. The results suggest an unprecedented function for a plant seed serpin as a ?-amylase-specific chaperone-like partner that could optimize ?-amylase activity upon germination. This report is the first to describe a noninhibitory function for a serpin in plants.
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Project description:BackgroundTH2 cells have long been believed to play a pivotal role in allergic immune responses, including IgE antibody production and type 2 cytokine-mediated inflammation and pathology. A new T-cell subset, follicular helper T (TFH) cells, is specialized in supporting B-cell maturation and antibody production.ObjectiveWe sought to investigate the roles of TFH cells in allergic immune responses.MethodsNaive mice were exposed to cytokines or natural allergens through the airways. Development of allergic immune responses was analyzed by collecting draining lymph nodes and sera and by challenging the animals. Cytokine reporter mice and gene-deficient mice were used to dissect the immunologic mechanisms.ResultsWe observed the development of IL-4-producing TFH cells and TH2 cells in draining lymph nodes after airway exposure to IL-1 family cytokines or natural allergens. TFH and TH2 cells demonstrated unique phenotypes, tissue localization, and cytokine responses. TFH cells supported the sustained production of IgE antibody in vivo in the absence of other T-cell subsets or even when TH2 cell functions were severely compromised. Conversely, conditional deficiency of the master regulator Bcl6 in CD4+ T cells resulted in a marked reduction in TFH cell numbers and IgE antibody levels, but type 2 cytokine responses and eosinophilic inflammation in the airways remained unaffected.ConclusionTFH cells play critical roles in the regulation of IgE antibody production. Allergic immune responses to airborne allergens likely involve 2 distinct subsets of IL-4-producing CD4+ T cells, namely TFH and Th2 cells.
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Project description:BackgroundVarious clinical patterns based on routes of sensitization and sensitized allergens are reported in adult-onset IgE-mediated wheat allergy. There is still a paucity of data on IgE-bound wheat allergen profiles in wheat challenge-proven adult-onset wheat allergic cases. Therefore, we aim to identify the major sensitized allergens in Thai adult-onset wheat allergic patients whose first symptom occurred after the age of 18 years despite previous tolerance.MethodsThis cross-sectional pilot study recruited patients from the Thai Adult-onset IgE-mediated Wheat Allergy Cohort (TAWAC). The sera of patients with mostly challenge-proven cases were selected for allergen study, including ImmunoCAP and IgE-bound gliadins along with glutenins profiles. The IgE-bound proteins were identified by liquid chromatography-tandem mass spectrophotometry (LC-MS/MS). Direct binding of IgE to recombinant gliadin and glutenin was performed to confirm the results of immunoblot and LC-MS/MS.ResultsEleven wheat-dependent exercise-induced anaphylaxis (WDEIA) and 4 typical wheat allergy (WA) patients were enrolled. Serum IgE from >50% of bound proteins had a molecular weight ranging from 35 to 55 kDa in both gliadin and glutenin extracts. Further, ELISA demonstrated that γ-gliadin and ω5-gliadin were the most important major allergens. Other major allergens include α/β-gliadin, HMW glutenin, and possibly α-amylase inhibitor or LWM glutenin. Gamma-gliadin sensitization was found in all WA patients (4/4), while ω-5 gliadin was found in all WDEIA patients (11/11) from ELISA.ConclusionWheat γ-gliadin and ω-5 gliadin are major wheat allergens among adult-onset wheat allergy patients in Thailand. Component-resolved diagnosis using γ-gliadin might be helpful in high suspicion of wheat allergy.
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