Molecular cloning, purification, and IgE-binding of a recombinant class I chitinase from Hevea brasiliensis leaves (rHev b 11.0102)

[Hevea brasiliensis como fuente alergénica: revisión bibliográfica]

Abstract

La planta Hevea brasiliensis se utiliza ampliamente en la industria como fuente de extracción de caucho, un elemento empleado en diversas áreas comerciales y médicas. Los estudios inmunológicos de esta especie indican que es una fuente alergénica importante, que puede provocar sensibilización y alergia. Se han identificado diferentes componentes alergénicos de esta planta, con diversas propiedades inmunitarias y bioquímicas, y estudiado más de diez tipos diferentes de alérgenos, cada uno con distinta capacidad de inducir síntomas alérgicos. En esta revisión informamos los avances actuales en el estudio de Hevea brasiliensis.

Hevea latex-associated allergies: piecing together the puzzle of the latex IgE reactivity profile

Introduction: IgE-mediated Hevea latex allergy and associated food-allergies constitute a significant health issue with serious consequences of diagnostic error. Hence, there is a need for more reliable confirmatory diagnostics.Areas covered: Here, we summarize the major limitations of conventional tests using native extracts and describe how piecing together the IgE reactivity profile can benefit correct diagnosis in difficult cases in whom conventional tests yield equivocal or negative results. A diagnostic algorithm integrating traditional sIgE and component-resolved diagnosis (CRD) is presented.Expert opinion: Moreover, it is clear that the discoveries in the field of the Hevea latex proteome will contribute to our understandings and accurate approach of sometimes complex cross-reactivity phenomena that extend beyond the 'latex-fruit syndrome.'

Food allergies resulting from immunological cross-reactivity with inhalant allergens: Guidelines from the German Society for Allergology and Clinical Immunology (DGAKI), the German Dermatology Society (DDG), the Association of German Allergologists (AeDA) and the Society for Pediatric Allergology and Environmental Medicine (GPA)

A large proportion of immunoglobulin E (IgE)-mediated food allergies in older children, adolescents and adults are caused by cross-reactive allergenic structures. Primary sensitization is most commonly to inhalant allergens (e.g. Bet v 1, the major birch pollen allergen). IgE can be activated by various cross-reactive allergens and lead to a variety of clinical manifestations. In general, local and mild — in rare cases also severe and systemic — reactions occur directly after consumption of the food containing the cross-reactive allergen (e. g. plant-derived foods containing proteins of the Bet v 1 family). In clinical practice, sensitization to the primary responsible inhalant and/or food allergen can be detected by skin prick tests and/or in vitro detection of specific IgE. Component-based diagnostic methods can support clinical diagnosis. For individual allergens, these methods may be helpful to estimate the risk of systemic reactions. Confirmation of sensitization by oral provocation testing is important particulary in the case of unclear case history. New, as yet unrecognized allergens can also cause cross-reactions.

The therapeutic potential of specific immunotherapy (SIT) with inhalant allergens and their effect on pollen-associated food allergies is currently unclear: results vary and placebo-controlled trials will be necessary in the future. Pollen allergies are very common. Altogether allergic sensitization to pollen and cross-reactive food allergens are very common in our latitudes. The actual relevance has to be assessed on an individual basis using the clinical information.

Cite this as Worm M, Jappe U, Kleine-Tebbe J, Schäfer C, Reese I, Saloga J, Treudler R, Zuberbier T, Wassmann A, Fuchs T, Dölle S, Raithel M, Ballmer-Weber B, Niggemann B, Werfel T. Food allergies resulting from immunological cross-reactivity with inhalant allergens. Allergo J Int 2014; 23: 1–16 DOI 10.1007/s40629-014-0004-6

Generation and characterization of anti-chitinase monoclonal antibodies

Class IV chitinase, an allergenic protein of Vitis vinifera (grape), was purified by anion exchange chromatography and used for immunization of Balb/c mice. Monoclonal antibodies (MAbs) were raised by hybridoma technology using Sp2/0 myeloma cells. Finally after three limiting dilutions, six stable clones were generated. Antibody isotyping showed that IgG(2a), IgG(2b), and IgM were produced by one, two, and three of the clones, respectively. All of the MAbs had kappa light chain. The affinities were in the range of 3 × 10(8) to 1.2 × 10(9) M(-1). The MAbs were specific for grape chitinase as confirmed by Western blotting. In conclusion, we successfully produced several MAbs against grape class IV chitinase, which could be used for assessment of this allergen in different grape cultivars.

Quantitative analysis of immunoglobulin E reactivity profiles in patients allergic or sensitized to natural rubber latex (Hevea brasiliensis)

BACKGROUND

Characterized native and recombinant Hevea brasiliensis (rHev b) natural rubber latex (NRL) allergens are available to assess patient allergen sensitization profiles.

OBJECTIVE

Quantification of individual IgE responses to the spectrum of documented NRL allergens and evaluation of cross-reactive carbohydrate determinants (CCDs) for more definitive diagnosis.

METHODS

Sera of 104 healthcare workers (HCW; 51 German, 21 Portuguese, 32 American), 31 spina bifida patients (SB; 11 German, 20 Portuguese) and 10 Portuguese with multiple surgeries (MS) were analysed for allergen-specific IgE antibody (sIgE) to NRL, single Hev b allergens and CCDs with ImmunoCAP technology.

RESULTS

In all patient groups rHev b 5-sIgE concentrations were the most pronounced. Hev b 2, 5, 6.01 and 13 were identified as the major allergens in HCW and combined with Hev b 1 and Hev b 3 in SB. In MS Hev b 1 displayed an intermediate relevance. Different sIgE antibody levels to native Hevea brasiliensis (nHev b) 2 and rHev b 6.01 allowed discrimination of SB with clinical relevant latex allergy vs. those with latex sensitization. Sensitization profiles of German, Portuguese and American patients were equivalent. rHev b 5, 6.01 and nHev b 13 combined detected 100% of the latex-allergic HCW and 80.1% of the SB. Only 8.3% of the sera showed sIgE response to CCDs.

CONCLUSIONS

Hev b 1, 2, 5, 6.01 and 13 were identified as the major Hev b allergens and they should be present in standardized latex extracts and in vitro allergosorbents. CCDs are only of minor relevance in patients with clinical relevant latex allergy. Component-resolved diagnostic analyses for latex allergy set the stage for an allergen-directed immunotherapy strategy.

Occupational allergy to latex among loom tuners in a textile factory

BACKGROUND

Occupational allergy to latex is generally reported from occupational groups such as health care workers; however, few reports derive from other occupational settings.

METHODS

Two male subjects working as loom tuners in a textile manufacturing plant developed severe allergic reactions during the cutting and weaving of elastic bands, initially not suspected to contain latex constituents. Clinical evaluation and lung function tests were supplemented by skin prick testing, specific IgE evaluation and basophil activation assays with extracted elastic bands.

RESULTS

Both workers presented with rhinitis, episodes of tight chest and itchy eyes. Initial spirometry was normal with no significant reversibility; however, a histamine challenge test was positive in one worker. Skin prick testing to a battery of common inhalant allergens was negative; however, raised IgE levels were detected to latex using ImmunoCAP. On further testing, the specific IgE response was directed mainly to the major latex allergens rHev b 5, rHev b 6.01, rHev b 6.02 and nHev b 13. Basophils of the two workers, but not the unaffected control subjects, were strongly activated by extracts of the elastic and the cutting dust material.

CONCLUSIONS

Workers are at high risk of becoming sensitised to latex allergens when exposed to excessive dust produced by loom tuning machines. Latex sensitisation should therefore be considered in workers developing unexplained work-related allergic reactions (including asthma) associated with unlabelled materials in the textile industry.

Relevance of the recombinant lipid transfer protein of Hevea brasiliensis: IgE-binding reactivity in fruit-allergic adults

BACKGROUND

Lipid transfer proteins (LTPs) are relevant allergens in certain plants. The role of the LTP of Hevea brasiliensis in the latex-fruit syndrome is widely unknown.

OBJECTIVE

To study IgE reactivity with recombinant Hevea LTP in sera of fruit-allergic adults with and without natural rubber latex (NRL) allergy.

METHODS

An LTP-specific complementary DNA of H brasiliensis leaves was amplified, subcloned into the pMAL expression system, and analyzed. The recombinant protein was coupled to ImmunoCAP, and the IgE-binding properties were studied in sera of 10 NRL-allergic patients without symptoms to fruit and 48 atopic patients with fruit allergy. Eleven of these 48 patients were also allergic to NRL, 14 displayed sensitization to NRL without symptoms on NRL exposure so far, and 23 had neither symptoms nor IgE antibodies to NRL.

RESULTS

After expression in Escherichia coli, a soluble maltose-binding protein-rHev b 12 fusion protein was isolated and coupled to ImmunoCAP to determine rHev b 12 specific IgE reactivity. rHev b 12 specific IgE binding was found in 3 fruit-allergic patients with NRL sensitization (0.68, 0.88, and 0.96 kU/L) and in 3 fruit-allergic patients without NRL sensitization (1.58, 2.25, and 2.27 kU/L). The remaining 52 serum samples and all maltose-binding protein control test results were negative (< 0.35 kU/L).

CONCLUSIONS

In these patients, rHev b 12 specific IgE reactivity seems to result from common cross-reactive epitopes with some of the fruit LTPs tested and underscores only an involvement in co-recognition. No clinical relevance of IgE binding to the LTP of H brasiliensis in association with NRL allergy was detected.

A single amino acid substitution on the surface of a natural hevein isoform (Hev b 6.0202), confers different IgE recognition

Decreased immune reactivity of isoforms of major allergens has been reported. However, such claims have always been based on experiments with recombinant proteins. This work describes the molecular and physicochemical characterization of a hevein (Hev b 6.0201) natural isoform (Hev b 6.0202), which is present in rubber latex from Hevea brasiliensis. The isoallergen has a single substitution Asn14Asp, which gives rise to local differences in the surface potential, as observed from the crystal structure presented here. Besides, ELISA inhibition using serum pools of adult and pediatric patients showed reduced IgE-binding capacity ( approximately 27%) with the isoallergen. Overall, these results are relevant to delineate crucial residues involved in this dominant discontinuous epitope.

Basophil Activation Test and specific IgE measurements using a panel of recombinant natural rubber latex allergens to determine the latex allergen sensitization profile in children

There are no documented studies that describe natural rubber latex (NRL) sensitization in children with a history of surgical intervention but without any congenital malformation (urogenital anomalies, spina bifida, etc.), although some authors have studied NRL allergy in children without a history of surgical intervention. The aim of this work was to evaluate the sensitization profile to single NRL allergens in children without spina bifida and without repeated surgical interventions, by using different recombinant and natural latex allergens in two analytical techniques: specific serum immunoglobulin E (IgE) quantification and flow cytometry determination of activated basophils expressing CD63, after stimulating cells from patients with NRL allergens. A total of 23 patients and 10 healthy children were selected. Conjunctival and in-use NRL provocation tests were carried out, as well as specific IgE determination in all patients' and controls' sera with the recombinant NRL allergens: rHev b 1, rHev b 2, rHev b 3, rHev b 5, rHev b 6.01, rHev b 6.02, rHev b 8, rHev b 9 and rHev b 11 and with NRL (k82) using appropriate ImmunoCAPs. The Basophil Activation Test (BAT) was performed with whole latex extract and with the recombinant allergens rHev b 5 and rHev b 6.01, as well as with the natural allergen Hev b 6.02. The sensitivity and the specificity of NRL-specific IgE (k82) were 100%. Positive IgE responses to rHev b 5 were found in sera of 10 children, to rHev b 6.01 in 16 and for rHev b 6.02 in 15 children's sera. Specific IgE to rHev b 8 was found in four sera of the children. We only found significant differences in sensitization to rHev b 5 in children with two or more surgical interventions compared with the non-intervened group or those with only one intervention. Specific IgE in sera of children with latex-fruit syndrome recognized rHev b 6.02, but not to rHev b 11. The patients sensitized to Hev b 8, Hev b 9 and/or Hev b 11 were atopic. The four patients presenting a positive response to the NRL profilin Hev b 8 were allergic to pollen. The BAT against whole NRL extract was positive in 22 of 23 children; against rHev b 5 in 14 of the patients studied; against rHev b 6.01 in seven cases and against nHev b 6.02 in 19 children. In all the control subjects, the results using this technique were negative. If combined rHev b 5, rHev b 6.01 and nHev b 6.02 together, BAT could detect 20 of the 23 children with latex allergy. The combined use of ImmunoCAP with all the recombinant NRL allergens and BAT with rHev b 5, rHev b 6.01 and nHev b 6.02, enabled the identification of NRL allergy in 22 of 23 patients. There is a positive and significant correlation between sensitization to Hev b 5 and the number of interventions. BAT and allergen-specific IgE determination could be used as first-line in vitro diagnostic tests in patients with NRL allergy.

Identification of an obeche (Triplochiton scleroxylon) wood allergen as a class I chitinase

BACKGROUND

Wood dust is known to cause allergic occupational asthma and obeche (Triplochiton scleroxylon) is a prominent exponent in this field. However, the knowledge about wood allergens is still limited. The aim of this study was to identify and characterize obeche wood allergens.

METHODS

Obeche extracts were prepared from freshly ground in comparison to 7 years stored wood dust and investigated by Sodium dodecyl sulfate-polyacrylamid gel electrophoresis, enzyme-linked allergosorbent test and immunoglobulin (Ig)E-immunoblot. Allergens were detected by specific IgE of seven obeche allergic patients' sera and protein analysis was performed by mass spectrometry. Cross-reactivity was demonstrated by ImmunoCAP-inhibition with sera of seven obeche and four latex-allergic patients.

RESULTS

Obeche extracts showed different protein pattern and IgE-binding capacities depend on the age of the wood dust. A 38 kDa protein was identified as major obeche wood allergen, detected by six of seven (85%) obeche allergic patients' sera and was entitled as Trip s 1. Trip s 1 is homologous to plant class I chitinases and exhibited enzyme activity demonstrated by chitinolysis. Co-recognition or cross-reactivity of Trip s 1 according to structural similarity was seen in sera of latex allergic patients. IgE inhibition studies with obeche as solid phase and Trip s 1 and latex hevein as inhibitor demonstrated that Trip s 1 was a more effective inhibitor in obeche as well as in latex allergic patients' sera.

CONCLUSIONS

Trip s 1 is a new obeche wood allergen of the plant class I chitinase family. This finding may explain the dominant role of obeche in sensitization against wood dust.

Hevea brasiliensis latex allergens: current panel and clinical relevance

Latex allergy has been studied in detail in Europe and the US over the past two decades, resulting in specific guidelines that succeeded in reducing its incidence in high-risk populations within the medical field. How these developments have affected high-risk populations outside the health care scenario is an important unanswered question. In addition, a second wave of latex allergy may occur in nations that are striving to attain higher economic and technologic standards, including population-dense countries such as China. Therefore, the application of Hevea allergens in novel diagnostic assays and the development of specific latex immunotherapy will provide new opportunities for latex allergy research. In this review, we summarize current knowledge on the immunological properties of the 13 officially accepted Hevea brasiliensis latex allergens.

Toxicological and immunological aspects of occupational latex allergy

Latex allergy continues to be an important occupational health problem as latex products are used increasingly worldwide, particularly in healthcare. Although there are few epidemiological studies on the incidence of latex allergy, there has been an increase in the number of case reports over the last 10 years and, based on skin-prick tests, estimates of prevalence of latex allergy in healthcare workers range from 2% to 17%. The allergic health effects arise either from the latex proteins, generally causing a type I immediate hypersensitivity reaction, or from the chemicals added to latex during processing, causing a type IV delayed hypersensitivity reaction. Clinical manifestations of latex allergy depend on the route of exposure and occur by direct contact either with skin or mucosa, or by inhalation. The diagnosis of latex allergy is based on the history, skin tests, serological tests and challenge tests. Thirteen latex allergens have been identified and isolated so far from natural rubber latex. They differ in their potential to elicit immunological responses in individuals allergic to latex and thus have been designated as major or minor allergens. In latex gloves, cornstarch powder used as a donning agent carries latex proteins, thereby increasing inhalational and mucosal exposure to latex proteins. There also appears to be a positive correlation between protein content and allergenicity of gloves. The use of powder-free, low-protein gloves is effective in reducing symptoms and markers of sensitisation. Alternatives to latex gloves, such as nitrile or vinyl gloves are available but may be inferior in respect to manual dexterity and biological impermeability.

Natural rubber latex allergens: new developments

PURPOSE OF REVIEW

New allergenic latex proteins have been identified, whereas further information on known latex allergens has emerged in recent years. Although prevalence figures for sensitization to the various latex allergens have been published in several studies in the past, the data have not been collated to facilitate cross-comparison.

RECENT FINDINGS

Salient characteristics of the three most recently identified latex allergens, Hev b 11, 12 and 13 are described, whereas new findings on some of the previously recognized allergens are examined. Hev b 2 is viewed from the standpoint of allergenicity and protein glycosylation, Hev b 4 in relation to its biochemical identity and molecular cloning, Hev b 5 with respect to its recombinant form, and Hev b 6 in connection with conformational IgE epitopes. Reports on sensitization or allergic reaction to purified latex allergens from recent and past work are summarized. The use of latex allergens in latex allergy diagnostics is reviewed and discussed.

SUMMARY

Thirteen latex allergens have been recognized by the International Union of Immunological Societies. Based on the results of published studies, native Hev b 2, recombinant Hev b 5, native or recombinant Hev b 6, native Hev b 13, and possibly native Hev b 4 are the major allergens relevant to latex-sensitized adults. Although there is an increasing tendency to identify and characterize latex allergens largely on the basis of their recombinant forms, not all such recombinant proteins have been fully validated against their native counterparts with respect to clinical significance.

Allermatch, a webtool for the prediction of potential allergenicity according to current FAO/WHO Codex alimentarius guidelines

Background

Novel proteins entering the food chain, for example by genetic modification of plants, have to be tested for allergenicity. Allermatch™ is a webtool for the efficient and standardized prediction of potential allergenicity of proteins and peptides according to the current recommendations of the FAO/WHO Expert Consultation, as outlined in the Codex alimentarius.

Description

A query amino acid sequence is compared with all known allergenic proteins retrieved from the protein databases using a sliding window approach. This identifies stretches of 80 amino acids with more than 35% similarity or small identical stretches of at least six amino acids. The outcome of the analysis is presented in a concise format. The predictive performance of the FAO/WHO criteria is evaluated by screening sets of allergens and non-allergens against the Allermatch databases. Besides correct predictions, both methods are shown to generate false positive and false negative hits and the outcomes should therefore be combined with other methods of allergenicity assessment, as advised by the FAO/WHO.

Conclusions

Allermatch™ provides an accessible, efficient, and useful webtool for analysis of potential allergenicity of proteins introduced in genetically modified food prior to market release that complies with current FAO/WHO guidelines.