Increased allergen production in turnip (Brassica rapa) by treatments activating defense mechanisms

Performance-Enhancing Materials in Medical Gloves

Medical gloves, along with masks and gowns, serve as the initial line of defense against potentially infectious microorganisms and hazardous substances in the health sector. During the COVID-19 pandemic, medical gloves played a significant role, as they were widely utilized throughout society in daily activities as a preventive measure. These products demonstrated their value as important personal protection equipment (PPE) and reaffirmed their relevance as infection prevention tools. This review describes the evolution of medical gloves since the discovery of vulcanization by Charles Goodyear in 1839, which fostered the development of this industry. Regarding the current market, a comparison of the main properties, benefits, and drawbacks of the most widespread types of sanitary gloves is presented. The most common gloves are produced from natural rubber (NR), polyisoprene (IR), acrylonitrile butadiene rubber (NBR), polychloroprene (CR), polyethylene (PE), and poly(vinyl chloride) (PVC). Furthermore, the environmental impacts of the conventional natural rubber glove manufacturing process and mitigation strategies, such as bioremediation and rubber recycling, are addressed. In order to create new medical gloves with improved properties, several biopolymers (e.g., poly(vinyl alcohol) and starch) and additives such as biodegradable fillers (e.g., cellulose and chitin), reinforcing fillers (e.g., silica and cellulose nanocrystals), and antimicrobial agents (e.g., biguanides and quaternary ammonium salts) have been evaluated. This paper covers these performance-enhancing materials and describes different innovative prototypes of gloves and coatings designed with them.

Are Dietary Lectins Relevant Allergens in Plant Food Allergy?

Lectins or carbohydrate-binding proteins are widely distributed in seeds and vegetative parts of edible plant species. A few lectins from different fruits and vegetables have been identified as potential food allergens, including wheat agglutinin, hevein (Hev b 6.02) from the rubber tree and chitinases containing a hevein domain from different fruits and vegetables. However, other well-known lectins from legumes have been demonstrated to behave as potential food allergens taking into account their ability to specifically bind IgE from allergic patients, trigger the degranulation of sensitized basophils, and to elicit interleukin secretion in sensitized people. These allergens include members from the different families of higher plant lectins, including legume lectins, type II ribosome-inactivating proteins (RIP-II), wheat germ agglutinin (WGA), jacalin-related lectins, GNA (Galanthus nivalis agglutinin)-like lectins, and Nictaba-related lectins. Most of these potentially active lectin allergens belong to the group of seed storage proteins (legume lectins), pathogenesis-related protein family PR-3 comprising hevein and class I, II, IV, V, VI, and VII chitinases containing a hevein domain, and type II ribosome-inactivating proteins containing a ricin B-chain domain (RIP-II). In the present review, we present an exhaustive survey of both the structural organization and structural features responsible for the allergenic potency of lectins, with special reference to lectins from dietary plant species/tissues consumed in Western countries.

Influence of Heavy Metals (Ni, Cu, and Zn) on Nitro-Oxidative Stress Responses, Proteome Regulation and Allergen Production in Basil (Ocimum basilicum L.) Plants

One of the most significant biosphere contamination problems worldwide is derived from heavy metals. Heavy metals can be highly reactive and toxic according to their oxidation levels. Their toxic effects are associated with the increased production of reactive oxygen species (ROS) and cellular damage induced in plants. The present study focuses on the effects of nickel (Ni), copper (Cu), and zinc (Zn) applied to the soil on the antioxidant response and allergen production in the aromatic plant basil (Ocimum basilicum L.) following a combined physiological, biochemical and analytical approach. The concentrations used for the three heavy metals were based on the 2002 Regulation of the Polish Ministry of the Environment on Soil Quality Standards [(i) agricultural land (group B): Ni 100 ppm, Ni 210 ppm, Cu 200 ppm, Cu 500 ppm, Zn 720 ppm and (ii) industrial land (group C): Ni 500 ppm, Cu 1000 ppm, Zn 1500 ppm, Zn 3000 ppm]. The highest physiological and cellular damage in basil plants was caused by Cu and Zn. Increasing concentrations of Cu resulted in a further increase in cellular damage and nitro-oxidative stress, correlating with an induction in activity of reactive oxygen and nitrogen species metabolism enzymes (SOD, CAT, APX, NR). Treatment with Cu led to increased concentration of the allergenic protein profilin, while increasing concentrations of Cu and Zn led to a decrease in the concentration of total proteins (likely due to proteolysis) and antioxidant capacity. Interestingly, severe Cu stress resulted in the accumulation of specific proteins related to transpiration and photosynthetic processes. On the basis of these findings, Ni stress in basil plants appears to be less damaging and with lower allergenic potential compared with Cu and Zn stress, while Cu-stressed basil plants experience most detrimental effects and display highest allergen production.

Plant food allergy: Influence of chemicals on plant allergens

Plant-derived foods are the most common allergenic sources in adulthood. Owing to the rapidly increasing prevalence of plant food allergies in industrialized countries, the environmental factors are suspected to play a key role in development of allergic sensitization. The present article provides an overview of ways by which chemicals may influence the development and severity of allergic reactions to plant foods, with especial focus on plant allergens up-regulated under chemical stress. In plants, a substantial part of allergens have defense-related function and their expression is highly influenced by environmental stress and diseases. Pathogenesis-related proteins (PR) account for about 25% of plant food allergens and some are responsible for extensive cross-reactions between plant-derived foods, pollen and latex allergens. Chemicals released by anthropogenic sources such as agriculture, industrial activities and traffic-related air pollutants are potential drivers of the increasing sensitization to allergenic PRs by elevating their expression and by altering their immunogenicity through post-translational modifications. In addition, some orally-taken chemicals may act as immune adjuvants or directly trigger non-IgE mediated food allergy. Taken together, the current literature provides an overwhelming body of evidence supporting the fact that plant chemical exposure and chemicals in diet may enhance the allergenic properties of certain plant-derived foods.

Environmental stress is the major cause of transcriptomic and proteomic changes in GM and non-GM plants

The approval of genetically modified (GM) crops is preceded by years of intensive research to demonstrate safety to humans and environment. We recently showed that in vitro culture stress is the major factor influencing proteomic differences of GM vs. non-GM plants. This made us question the number of generations needed to erase such "memory". We also wondered about the relevance of alterations promoted by transgenesis as compared to environment-induced ones. Here we followed three rice lines (1-control, 1-transgenic and 1-negative segregant) throughout eight generations after transgenesis combining proteomics and transcriptomics, and further analyzed their response to salinity stress on the F6 generation. Our results show that: (a) differences promoted during genetic modification are mainly short-term physiological changes, attenuating throughout generations, and (b) environmental stress may cause far more proteomic/transcriptomic alterations than transgenesis. Based on our data, we question what is really relevant in risk assessment design for GM food crops.

Grapevine Downy Mildew Plasmopara viticola Infection Elicits the Expression of Allergenic Pathogenesis-Related Proteins

BACKGROUND

Downy mildews are a group of microorganisms belonging to the Chromista kingdom that can infect specific plants. When growing on plant tissues these microbes can elicit the expression of pathogenesis-related proteins (PRs), a group of stress-induced proteins frequently described as allergens in many plant species. Our aim was to verify by a proteomic approach whether the allergic reactions experienced by a farmer working in a vineyard infected by Plasmopara viticola (Pv), the etiological agent of downy mildew, are elicited by PRs expressed by the grapevine upon infection or by allergens present in Pv.

METHODS

A skin prick test and prick-to-prick test with infected field grapevine leaves and control leaves were carried out. Field leaves and ad hoc Pv-inoculated leaves were compared by SDS-PAGE and IgE-immunoblotting with extracts from control leaves and Pv sporangia. IgE-binding proteins were further separated by two-dimensional electrophoresis and the positive spots analyzed by nanoHPLC-Chip and tandem mass spectrometry (MS/MS) for identification.

RESULTS

Only infected leaves showed IgE-binding protein bands at 42 and 36 kDa. This agreed with the positive skin prick test experienced by the patient only with the infected leaves extract. Two-dimensional electrophoresis followed by MS/MS analysis led to the identification of PR-2 (β-1,3-glucanase) and harpin-binding protein 1 as putative allergens, the latter having never been reported before.

CONCLUSION

The results indicate that Pv infection might represent a new source of plant allergens.

Overview of plant chitinases identified as food allergens

Food allergies are induced by proteins belonging to a limited number of families. Unfortunately, relationships between protein structure and capacity to induce the immune response have not been completely clarified yet, which precludes possible improvements in the diagnosis, prevention, and therapy of allergies. Plant chitinases constitute a good example of food allergenic proteins for which structural analysis of allergenicity has only been carried out partially. In plants, there are at least five structural classes of chitinases plus a number of chitinase-related polypeptides. Their allergenicity has been mostly investigated for chitinases of class I, due to both their higher prevalence among plant chitinases and by the high structural similarity between their substrate-binding domain and hevein, a well-known allergen present in the latex of rubber trees. Even if allergenic molecules have been identified for at least three other classes of plant chitinases, the involvement of the different structural motifs in the allergenicity of molecules has been disregarded so far. In this review, we provide a structurally based catalog of plant chitinases investigated for allergenicity, which could be a useful base for further studies aimed at better clarifying the structure-allergenicity relationships for this protein family.

Maize IgE binding proteins: each plant a different profile?

Background

Allergies are nearly always triggered by protein molecules and the majority of individuals with documented immunologic reactions to foods exhibit IgE hypersensitivity reactions. In this study we aimed to understand if natural differences, at proteomic level, between maize populations, may induce different IgE binding proteins profiles among maize-allergic individuals. We also intended to deepen our knowledge on maize IgE binding proteins.

Results

In order to accomplish this goal we have used proteomic tools (SDS-PAGE and 2-D gel electrophoresis followed by western blot) and tested plasma IgE reactivity from four maize-allergic individuals against four different protein fractions (albumins, globulins, glutelins and prolamins) of three different maize cultivars. We have observed that maize cultivars have different proteomes that result in different IgE binding proteins profiles when tested against plasma from maize-allergic individuals. We could identify 19 different maize IgE binding proteins, 11 of which were unknown to date. Moreover, we found that most (89.5%) of the 19 identified potential maize allergens could be related to plant stress.

Conclusions

These results lead us to conclude that, within each species, plant allergenic potential varies with genotype. Moreover, considering the stress-related IgE binding proteins identified, we hypothesise that the environment, particularly stress conditions, may alter IgE binding protein profiles of plant components.

Current overview of allergens of plant pathogenesis related protein families

Pathogenesis related (PR) proteins are one of the major sources of plant derived allergens. These proteins are induced by the plants as a defense response system in stress conditions like microbial and insect infections, wounding, exposure to harsh chemicals, and atmospheric conditions. However, some plant tissues that are more exposed to environmental conditions like UV irradiation and insect or fungal attacks express these proteins constitutively. These proteins are mostly resistant to proteases and most of them show considerable stability at low pH. Many of these plant pathogenesis related proteins are found to act as food allergens, latex allergens, and pollen allergens. Proteins having similar amino acid sequences among the members of PR proteins may be responsible for cross-reactivity among allergens from diverse plants. This review analyzes the different pathogenesis related protein families that have been reported as allergens. Proteins of these families have been characterized in regard to their biological functions, amino acid sequence, and cross-reactivity. The three-dimensional structures of some of these allergens have also been evaluated to elucidate the antigenic determinants of these molecules and to explain the cross-reactivity among the various allergens.

Coping with abiotic stress: proteome changes for crop improvement

Plant breeders need new and more precise tools to accelerate breeding programs that address the increasing needs for food, feed, energy and raw materials, while facing a changing environment in which high salinity and drought have major impacts on crop losses worldwide. This review covers the achievements and bottlenecks in the identification and validation of proteins with relevance in abiotic stress tolerance, also mentioning the unexpected consequences of the stress in allergen expression. While addressing the key pathways regulating abiotic stress plant adaptation, comprehensive data is presented on the proteins confirmed as relevant to confer tolerance. Promising candidates still to be confirmed are also highlighted, as well as the specific protein families and protein modifications for which detection and characterization is still a challenge. This article is part of a Special Issue entitled: Translational Plant Proteomics.

Exposure to cadmium-contaminated soils increases allergenicity of Poa annua L. pollen

BACKGROUND

Pollution is considered as one main cause for the increase of allergic diseases. Air pollutants may cause and worsen airway diseases and are probably able to make pollen allergens more aggressive. Previous studies looked at traffic-related air pollution, but no data about the effects of polluted soils on pollen allergens are available. We aimed to assess the effects of plant exposure to cadmium-contaminated soil on allergenicity of the annual blue grass, Poa annua L, pollen.

METHODS

Poa plants were grown in soil contaminated or not contaminated (control) with cadmium. At flowering, mature pollen was analyzed by microscopy, to calculate the percentage of pollen grains releasing cytoplasmic granules, and by proteomic techniques to analyze allergen proteins. Allergens were identified by sera from grass pollen-allergic patients and by mass spectrometry.

RESULTS

Pollen from Cd-exposed plants released a higher amount of allergenic proteins than control plants. Moreover, Cd-exposed pollen released allergens-containing cytoplasmic grains much more promptly than control pollen. Group 1 and 5 allergens, the major grass pollen allergens, were detected both in control and Cd-exposed extracts. These were the only allergens reacting with patient's sera in control pollen, whereas additional proteins strengthening the signal in the gel region reacting with patient's sera were present in Cd-exposed pollen. These included a pectinesterase, a lipase, a nuclease, and a secretory peroxydase. Moreover, a PR3 class I chitinase-like protein was also immunodetected in exposed plants.

CONCLUSION

Pollen content of plants grown in Cd-contaminated soils is more easily released in the environment and also shows an increased propensity to bind specific IgE.

Clinical significance of cross-reactivity between tobacco and latex

BACKGROUND

Allergen cross-reactivity between tobacco and other species of Solanaceae family (tomato, potato, aubergine and egg plant) have been reported. We have recently studied IgE response to tobacco in asthmatic patients sensitised to Lolium perenne (Perennial rye grass pollen) and have found that 30% of the tobacco responsive patients also have latex sensitisation.

OBJECTIVE

The aim of our study was to investigate the possibility of cross-reactivity between tobacco and latex in asthmatic patients with IgE response to latex.

METHODS

A study was performed on tobacco and latex exposure in 15 patients who suffered from asthma and latex sensitisation and who were randomly chosen from our database of latex-sensitive patients. To identify tobacco and latex as possible allergens that might cause clinical specific responses, all these patients were tested with prick-tests, specific IgE to tobacco, latex and related allergens, bronchial challenge, and patch tests with tobacco, latex and nicotine. Immunological response was evaluated with immunoblotting, immunoblotting-inhibition and EAST-inhibition tests.

RESULTS

Positive prick and bronchial challenge with specific IgE>0.35 kU/L to tobacco was demonstrated in 11 asthmatics who were also sensitised to rye grass. Tobacco IgE level was related with sensitisation to latex (p<0.002), but not to other vegetables belonging to the Solanaceae family. EAST-inhibition and immunoblotting-inhibition showed the existence of cross-reactivity between tobacco and latex.

CONCLUSIONS

Cross-reactivity exists between latex and tobacco allergens. Smoker patients with IgE response to tobacco may be a risk population for latex sensitisation.

Proof of concept pilot study: prevalence of grass virus infection and the potential for effects on the allergenic potency of pollen

BACKGROUND

Wild plants harbour a variety of viruses and these have the potential to alter the composition of pollen. The potential consequences of virus infection of grasses on pollen-induced allergic disease are not known.

METHODS

We have collected pollen from Dactylis glomerata (cocksfoot; a grass species implicated as a trigger of allergic rhino-conjunctivitis) from Wytham Wood, Oxfordshire UK. Extracts were prepared from pollen from uninfected grass, and from grass naturally infected by the Cocksfoot streak potyvirus (CSV). Preparations of pollen from virus-infected and non-infected grasses were employed in skin testing 15 grass pollen-allergic subjects with hayfever. Allergen profiles of extracts were investigated by Western blotting for IgE with sera from allergic subjects.

RESULTS

The prevalence of CSV infection in cocksfoot grasses sampled from the study site varied significantly over an eight-year period, but infection rates of up to 70% were detected. Virus infection was associated with small alterations in the quantities of pollen proteins detected by polyacrylamide gel electrophoresis, and in the patterns of allergens identified by Western blotting with IgE from grass pollen allergic subjects. For individual subjects there were differences in potencies of standardised extracts of pollen from virus-free and virus-infected plants as assessed by skin testing, though a consistent pattern was not established for the group of 15 subjects.

CONCLUSION

Infection rates for CSV in cocksfoot grass can be high, though variable. Virus-induced alterations in components of grass pollen have the potential to alter the allergenic potency.

Molecular allergology approach to allergic diseases in the paediatric age

Identification, characterization, and purification of allergens are essential for the structural and immunologic studies needed to understand how these molecules induce specific IgE antibody production by the human immune system. Advances in molecular biology techniques have led to the production of recombinant allergens having constant properties, allowing detection of specific IgE directed against different molecular components of an allergenic source. Presence of homologous allergens in different sources is the reason for cross-reaction. Molecule-based diagnostic tools can lead to better interpretation of poly-sensitizations, observed by ST and in vitro tests using allergenic extracts as they were made before. Some examples IgE sensitization to major genuine allergens and panallergens will be presented.

Differential responses of Coffea arabica L. leaves and roots to chemically induced systemic acquired resistance

Coffea arabica is susceptible to several pests and diseases, some of which affect the leaves and roots. Systemic acquired resistance (SAR) is the main defence mechanism activated in plants in response to pathogen attack. Here, we report the effects of benzo(1,2,3)thiadiazole-7-carbothioic acid-S-methyl ester (BTH), a SAR chemical inducer, on the expression profile of C. arabica. Two cDNA libraries were constructed from the mRNA isolated from leaves and embryonic roots to create 1587 nonredundant expressed sequence tags (ESTs). We developed a cDNA microarray containing 1506 ESTs from the leaves and embryonic roots, and 48 NBS-LRR (nucleotide-binding site leucine-rich repeat) gene fragments derived from 2 specific genomic libraries. Competitive hybridization between untreated and BTH-treated leaves resulted in 55 genes that were significantly overexpressed and 16 genes that were significantly underexpressed. In the roots, 37 and 42 genes were over and underexpressed, respectively. A general shift in metabolism from housekeeping to defence occurred in the leaves and roots after BTH treatment. We observed a systemic increase in pathogenesis-related protein synthesis, in the oxidative burst, and in the cell wall strengthening processes. Moreover, responses in the roots and leaves varied significantly.

[Latex allergy]

Latex allergy has become an increasing cause of morbility in the last few years and is now recognized as an international health problem. The prevalence of latex sensitization among the general population is less than 1 %. The groups at highest risk include healthcare workers, rubber industry workers, patients with a history of multiple surgical procedures, particularly children with spina bifida and urogenital abnormalities, atopic individuals, and patients with certain fruit allergies (especially kiwi, avocado, chestnut and banana). The molecular and immunological characteristics of several natural latex allergens have been identified. Symptoms range from contact urticaria to anaphylaxis. Diagnosis is based on clinical history and is confirmed by skin prick tests. Measurement of serum specific IgE to latex can also be useful. The best treatment is latex avoidance and substitution by other materials. However, because latex products are ubiquitous in medical and nonmedical devices of daily use, a latex-free environment is not easy to achieve. In some patients, immunotherapy could be an alternative.

The hevein domain of the major latex-glove allergen Hev b 6.01 contains dominant T cell reactive sites

BACKGROUND

Sensitization to natural rubber latex (Hevea brasiliensis) is a major cause of occupational asthma and rhinitis affecting frequent latex-glove users. Hev b 6.01, a known major latex allergen, is cleaved naturally into hevein (4.7 kDa) and a C-terminal fragment (14 kDa). Hevein is an abundant protein in latex-glove extracts. As the immune response to allergens is initiated by activation of allergen-specific CD4(+) T cells, identification of dominant T cell epitopes is crucial for the development of specific immunotherapy.

OBJECTIVE

To identify dominant T cell epitopes of Hev b 6.01 in latex-allergic glove users.

METHODS

Ten latex-allergic frequent glove users and six non-latex-allergic atopic control subjects were selected, based on clinical symptoms and positive latex-specific serum IgE. Serum IgE reactivity to glove extract and recombinant Hev b 6.01 (rHev b 6.01) were analysed by ELISA. Latex-specific short-term oligoclonal T cell lines were generated from peripheral blood of latex-allergic subjects. These lines were tested for proliferative responses to overlapping 20-mer peptides of the Hev b 6.01 molecule. CD4(+) T cell intracellular cytokines, IL-4 and IFN-gamma were assessed following stimulation with immobilized anti-CD3 in the presence of IL-2.

RESULTS

All ten of the latex-allergic patients showed serum IgE binding to glove extract while eight of these also showed IgE binding to rHev b 6.01 by ELISA. Western blotting confirmed reactivity with rHev b 6.01 at around 20 kDa. T cell proliferation assays showed that latex-specific T cell lines from all subjects responded to one or more peptides, with greatest frequency of reactivity to peptides Hev b 6.01 p(10-29) and Hev b 6.01 p(19-38) in the hevein domain. An allergic-type cytokine profile with considerable IL-4 in addition to IFN-gamma was evident from intracellular cytokine staining.

CONCLUSION

Hevein is an important T cell as well as B cell immunogen and contains dominant T cell reactive sites.

Allergic cross-reactivity: from gene to the clinic

A large number of allergenic proteins have now their complete cDNA sequences determined and in some cases also the 3D structures. It turned out that most allergens could be grouped into a small number of structural protein families, regardless of their biological source. Structural similarity among proteins from diverse sources is the molecular basis of allergic cross-reactivity. The clinical relevance of immunoglobulin E (IgE) cross-reactivity seems to be influenced by a number of factors including the immune response against the allergen, exposure and the allergen. As individuals are exposed to a variable number of allergenic sources bearing homologous molecules, the exact nature of the antigenic structure inducing the primary IgE immune response cannot be easily defined. In general, the 'cross-reactivity' term should be limited to defined clinical manifestations showing reactivity to a source without previous exposure. 'Co-recognition', including by definition 'cross-reactivity', could be used to describe the large majority of the IgE reactivity where co-exposure to a number of sources bearing homologous molecules do not allow unequivocal identification of the sensitizing molecule. The analysis of reactivity clusters in diagnosis allows the interpretation of the patient's reactivity profile as a result of the sensitization process, which often begins with exposure to a single allergenic molecule.

Implicación clínica de la reactividad cruzada entre alergenos

Cross reactivity describes the development of symptoms as a consequence of the presence of specific IgE to a protein without the subject having had previous contact with that protein. Cross-reactivity depends on factors such as the individual's immune response, the type and intensity of exposure and, above all, the type of allergen. The identification of pan-allergens, which are present in various animal and vegetable sources and which show great structural and sequential similarity, even among species with little taxonomic relation, explains the existence of distinct, well-defined cross-reactivity syndromes. Knowledge of these phenomena could have important diagnostic and therapeutic consequences.

Epicutaneous natural rubber latex sensitization induces T helper 2-type dermatitis and strong prohevein-specific IgE response

In addition to immediate type I allergy symptoms, natural rubber latex allergy may manifest as protein contact dermatitis on the hands of health-care workers and other natural rubber latex glove users. We examined whether repeated application of natural rubber latex on mouse skin causes sensitization to natural rubber latex and dermatitis. Epicutaneous sensitization with natural rubber latex produced a significant influx of mononuclear cells, CD4+ CD3+ cells, and eosinophils to the sensitized skin sites. The number of degranulated mast cells in natural rubber latex-sensitized skin sites was significantly higher compared with control sites treated with phosphate-buffered saline. The expression of interleukin-1beta and interleukin-4 mRNA was markedly increased in natural rubber latex-sensitized skin sites. Moreover, significant increases in the mRNA expression of chemokines CCL2 (monocyte chemoattractant protein-1), CCL11 (eotaxin-1), CCL3 (macrophage inflammatory protein-1alpha), and CCL4 (macrophage inflammatory protein-1beta) were found. In addition to the cutaneous inflammatory response, epicutaneous sensitization with natural rubber latex induced a striking increase in the total and specific immunoglobulin E levels but not in the immunoglobulin G2a levels. Intraperitoneal immunization with natural rubber latex induced a strong natural rubber latex-specific immunoglobulin G2a response, but only a weak immunoglobulin E response. We also studied the role of two major natural rubber latex allergens, the highly hydrophilic prohevein and the hydrophobic rubber elongation factor. Cutaneous application of natural rubber latex elicited a strong immunoglobulin E response against prohevein, but not against rubber elongation factor. On the contrary, intraperitoneal immunization with natural rubber latex elicited strong immunoglobulin G2a production to rubber elongation factor but not to prohevein. These results demonstrate that epicutaneous sensitization with natural rubber latex induces T helper 2-dominated dermal inflammation and strong immunoglobulin E response in this murine model of natural rubber latex induced protein contact dermatitis. Epicutaneous sensitization to natural rubber latex proteins eluting from latex gloves may therefore contribute to the development of hand dermatitis and also natural rubber latex-specific immunoglobulin E antibodies.

Latex allergies in the health care worker

A dramatic increase in the incidence of latex allergies in health care workers followed the surge in latex glove use accompanying the rise of human immunodeficiency virus (HIV) in the early 1980s. This increase in latex glove use was driven by the release of Universal Precautions issued by the Centers for Disease Control (CDC) in response to the rise of HIV and other blood-borne pathogens. Efforts to stem allergic responses in the workplace have relied on the substitution of other materials for latex. Unfortunately, there is so much latex in everyday life that avoiding this allergen is exceedingly difficult once one is sensitized. Additionally, there are numerous cross reactants that are present in the environment. The situation is further confounded by the introduction of genetically manipulated foods and agricultural products that contain defense proteins genetically inserted to protect plants from pests and pathogens. Many of these defense proteins are antigens that will cross react with latex. Sensitivity reactions, once developed, may progress to the point at which the health care worker is excluded from working. This report provides an overview of rubber products and cross reactants, allergic reactions, and latex sensitivity for the health care worker.

Enhancement of tomato allergenicity after treatment with plant hormones

BACKGROUND

Practical applications to enhance the productivity of agriculture by using plants with improved resistance to pathogens are expected to increase in the near future. Although tomato has been widely investigated for breeding purposes, there have been no studies on tomato allergenicity after plant hormones treatments.

METHODS

Prick by prick tests were carried out with different tomato samples (fruits grown under biological conditions without addition of chemical products, and treated with ethylene and salicylic acid) in eight patients with ages between 12 and 27 years who suffered from anaphylaxis episodes after eating raw tomatoes. An immunoblot experiment with the different tomato extracts was performed using sera from these eight patients and controls.

RESULTS

The wheals obtained in prick tests were significantly higher with the extracts of tomato treated with ethylene and SAA (chi(2) = 31.3, p < 0.0001) and the patients who presented higher wheal diameters in skin tests were those who had more severe episodes of anaphylaxis. Neither the protein stain nor the IgE immunodetection patterns clearly varied between the untreated and the hormone-treated samples.

CONCLUSIONS

In the case of anaphylaxis induced by tomato, the treatment with plant hormones induced a higher cutaneous response than with non-treated tomato, but the "in vitro" response was similar.

Latex-fruit syndrome

Natural rubber latex immunoglobulin E-mediated hypersensitivity is probably one of the most relevant challenges that has been faced in the treatment of allergies during recent years. Additionally, allergen cross-reactivity has arisen as another very important problem, in the difficulty in diagnosing it and in its clinical implications. It is clear that some latex allergens cross-react with plant-derived food allergens, the so-called latex-fruit syndrome, with evident clinical consequences. Although the foods most frequently involved are banana, avocado, kiwi, and chestnut, several others are also implicated. Investigations point to a group of defense-related plant proteins, class I chitinases, which cross-react with a major latex allergen, hevein, as the panallergens responsible for the syndrome. This review focuses on our current understanding of the latex-fruit syndrome.

The major conformational IgE-binding epitopes of hevein (Hev b6.02) are identified by a novel chimera-based allergen epitope mapping strategy

A novel approach to localize and reconstruct conformational IgE-binding epitope regions of hevein (Hev b6.02), a major natural rubber latex allergen, is described. An antimicrobial protein (AMP) from the amaranth Amaranthus caudatus was used as an immunologically non-IgE-binding adaptor molecule to which terminal or central parts of hevein were fused. Hevein and AMP share a structurally identical core region but have different N-terminal and C-terminal regions. Only 1 of 16 hevein-allergic patients showed weak IgE binding to purified native or recombinant AMP. Chimeric AMP with the hevein N terminus was recognized by IgE from 14 (88%) patients, and chimeric AMP with the hevein C terminus was recognized by IgE from 6 (38%) patients. In contrast, chimeric AMP containing the hevein core region was recognized by IgE from only two patients. When both the N-terminal and C-terminal regions of hevein were fused with the AMP core, IgE from all 16 patients bound to the chimera. This chimera was also able to significantly inhibit (>70%) IgE binding to the native hevein. On the contrary, linear synthetic peptides corresponding to hevein regions in the AMP chimeras showed no significant IgE binding capacity in either enzyme-linked immunosorbent assay or inhibition enzyme-linked immunosorbent assay. These results suggest that the IgE binding ability of hevein is essentially determined by its N-terminal and C-terminal regions and that major IgE-binding epitopes of hevein are conformational. The chimera-based epitope mapping strategy described here provides a valuable tool for defining structural epitopes and creating specific reagents for allergen immunotherapy.

Clinical implications of cross-reactive food allergens

As a consequence of the general increase in allergic sensitization, the prevalence of hypersensitivity reactions to multiple foods that share homologous proteins has become a significant clinical problem. A variety of these allergens conserved among plants (eg, profilin and lipid transfer proteins) and animals (eg, tropomyosin and caseins) have been characterized. Although studies with molecular biologic techniques have elucidated the nature of these ubiquitous allergens, clinical studies have lagged behind. The physician is called on to determine the risk of reaction to related foods among legumes, tree nuts, fish, shellfish, cereal grains, mammalian and avian food products, and a variety of other plant-derived foods that may share proteins with pollens, latex, and each other. Clinical evaluations require a careful history, laboratory evaluation, and in some cases oral food challenges. The pitfalls in the evaluation of food allergy-unreliable histories and limitations in laboratory assessment primarily caused by false-positive skin prick test responses/RAST results are magnified when dealing with cross-reactive proteins. This review focuses on the clinical data regarding cross-reacting food allergens with the goal of providing a background for improved risk assessment and a framework on which to approach these difficult clinical questions.

A local accumulation of the Ralstonia solanacearum PopA protein in transgenic tobacco renders a compatible plant-pathogen interaction incompatible

Plants activate disease resistance responses when they recognize pathogen-derived molecules (elicitors). Frequently, recognition results in a hypersensitive response (HR), which is characterized by local host cell death at the infection site. Here we describe a genetic engineering approach to generate an HR in plants, whether or not an invading micro-organism produces a recognized elicitor. To that aim we created transgenic tobacco plants in which the pathogen-inducible promoter of the hsr203J gene from tobacco controls the expression of the popA elicitor gene from Ralstonia solanacearum. Because PopA itself also induces the hsr203J promoter, transgenic plants rapidly accumulate the bacterial elicitor in the pathogen infection sites. The elicitor becomes converted in plant tissues into its fully active derivatives PopA1-PopA3, showing that the previously observed processing events are not dependent on the bacterial type III secretion system. The outcome of induced PopA accumulation is a localized HR and a high degree of resistance of the transgenic plants to an oomycete pathogen. The system is functional in hybrids between different tobacco varieties, and we show that the engineered resistance, but not the associated cell death, is dependent on the salicylic acid signalling cascade. Although the approach is powerful in generating oomycete resistance, the induced HR might affect plant health. Its application thus requires a careful selection of individual transgenic lines and trials with various pathogens.

Pathogenesis-related proteins of plants as allergens

OBJECTIVE

Many pathogenesis-related (PR) proteins from plants are allergenic. We review the evidence that PR proteins represent an increasingly important group of plant-derived allergens.

DATA SOURCES

A detailed literature search was conducted through PubMed and GenBank databases.

STUDY SELECTION

All reports in PubMed and GenBank related to PR protein allergens for which at least partial amino acid sequence is known were included.

RESULTS

Production of PR proteins by plants is induced in plants by stress. Members of PR-protein groups 2, 3, 4, 5, 8, 10, and 14 have demonstrated allergenicity. PR2-, 3-, 4-, and 8-homologous allergens are represented by the latex allergens. Cross-reactivity of PR3 latex allergen, Hev b 6.02, with some fruit allergens may be a reflection of the representation of homologous PR proteins among varied plants. The expression of one of the representative PR5-homologous cedar pollen allergens, Jun a 3, is highly variable across years and geographic areas, possibly because of variable induction of this PR protein by environmental factors. PR10-homologous birch pollen allergen, Bet v 1, is structurally similar to and cross-reacts with PR10 proteins from fruits (eg, Mal d 1) which cause oral allergy syndrome. PR14 allergens (eg, Zea m 14) consist of lipid transfer proteins found in grains and fruits and are inducers of anaphylaxis.

CONCLUSIONS

PR-homologous allergens are pervasive in nature. Similarity in the amino acid sequences among members of PR proteins may be responsible for cross-reactivity among allergens from diverse plants. Induced expression of PR-homologous allergens by environmental factors may explain varying degrees of allergenicity. Man-made environmental pollutants may also alter the expression of some PR protein allergens.

Digestibility of allergens extracted from natural rubber latex and vegetable foods

BACKGROUND

Several cross-reactive allergens are now known to be involved in the defense responses of higher plants. Such proteins are drawing the attention of plant breeders because of their antimicrobial or stress-alleviating activities. Plants genetically modified to express defense-related proteins are being developed. The current concern is focused on the allergenicity of these intentionally expressed proteins.

OBJECTIVE

It is believed that food allergens are proteins resistant to digestion. Digestibility tests have been accepted as an appropriate method for evaluating the allergenicity of newly introduced proteins. In this study we investigated the usefulness of this method for detecting allergens from natural rubber latex and vegetable foods.

METHODS

Proteins were extracted from rubber latex, potato, and 5 kinds of fruits. Simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were used for the digestibility test. An aliquot of each digest was periodically withdrawn and analyzed. Allergens were detected with pooled sera from individuals with latex allergy or patients given a diagnosis of oral allergy syndrome.

RESULTS

Most latex and vegetable food proteins were digested by the SGF within 4 minutes. Numerous allergens were also decomposed by the SGF within 8 minutes. Although vegetable food allergens were relatively stable in the SIF, kiwi allergens were substantially degraded by the SIF within 16 hours.

CONCLUSION

The pronounced lability of the plant-derived allergens was thought to reflect the discrete sensitization and elicitation processes of patients with latex-fruit syndrome or oral allergy syndrome. These results indicate that the allergenicity of a newly expressed protein should be carefully evaluated according to not only its digestibility but also other important properties.

Molecular and biochemical classification of plant-derived food allergens

Molecular biology and biochemical techniques have significantly advanced the knowledge of allergens derived from plant foods. Surprisingly, many of the known plant food allergens are homologous to pathogenesis-related proteins (PRs), proteins that are induced by pathogens, wounding, or certain environmental stresses. PRs have been classified into 14 families. Examples of allergens homologous to PRs include chitinases (PR-3 family) from avocado, banana, and chestnut; antifungal proteins such as the thaumatin-like proteins (PR-5) from cherry and apple; proteins homologous to the major birch pollen allergen Bet v 1 (PR-10) from vegetables and fruits; and lipid transfer proteins (PR-14) from fruits and cereals. Allergens other than PR homologs can be allotted to other well-known protein families such as inhibitors of alpha-amylases and trypsin from cereal seeds, profilins from fruits and vegetables, seed storage proteins from nuts and mustard seeds, and proteases from fruits. As more clinical data and structural information on allergenic molecules becomes available, we may finally be able to answer what characteristics of a molecule are responsible for its allergenicity.

Variable expression of pathogenesis-related protein allergen in mountain cedar (Juniperus ashei) pollen

Allergic diseases have been increasing in industrialized countries. The environment is thought to have both direct and indirect modulatory effects on disease pathogenesis, including alterating on the allergenicity of pollens. Certain plant proteins known as pathogenesis-related proteins appear to be up-regulated by certain environmental conditions, including pollutants, and some have emerged as important allergens. Thus, the prospect of environmentally regulated expression of plant-derived allergens becomes yet another potential environmental influence on allergic disease. We have identified a novel pathogenesis-related protein allergen, Jun a 3, from mountain cedar (Juniperus ashei) pollen. The serum IgE from patients with hypersensitivity to either mountain cedar or Japanese cedar were shown to bind to native and recombinant Jun a 3 in Western blot analysis and ELISA. Jun a 3 is homologous to members of the thaumatin-like pathogenesis-related (PR-5) plant protein family. The amounts of Jun a 3 extracted from mountain cedar pollen varied up to 5-fold in lots of pollen collected from the same region in different years and between different regions during the same year. Thus, Jun a 3 may contribute not only to the overall allergenicity of mountain cedar pollen, but variable levels of Jun a 3 may alter the allergenic potency of pollens produced under different environmental conditions.