Evaluation of IgE binding to proteins of hardy (Actinidia arguta), gold (Actinidia chinensis) and green (Actinidia deliciosa) kiwifruits and processed hardy kiwifruit concentrate, using sera of individuals with food allergies to green kiwifruit

Kiwifruit defense protein, kiwellin (Act d 5) percutaneously sensitizes mouse models through the epidermal application of crude kiwifruit extract

Background

Kiwifruit is a popular fruit consumed worldwide and is also used as a cosmetic ingredient. However, it is known to cause allergic reactions in humans. Recent studies have suggested an association between food allergy and food allergens entering the body via the skin. However, percutaneously sensitizing kiwifruit allergens have not been identified in human studies or in animal models.

Objective

This study aimed to identify kiwifruit proteins that percutaneously sensitized mice through the epidermal application of crude extracts from green and gold kiwifruit on the dorsal skin, and serum IgE and IgG1 levels were used as sensitization markers.

Design

BALB/c mice were back-shaved and their skin was exposed to crude extracts from green and gold kiwifruit that contained sodium dodecyl sulfate. Specific IgE and IgG1 antibodies generated and secreted in response to antigens were measured using enzyme-linked immunosorbent assay or immunoblotting.

Results

Skin exposure to kiwifruit extract induced an increase in the levels of kiwifruit-specific IgE and IgG1, which are helper T cell 2-related allergenic antibodies in mice. These antibodies reacted with 18, 23, and 24 kDa proteins found in both green and gold kiwifruits. Thus, three percutaneously sensitizing allergens were identified and purified. Their amino acid sequences partially matched with that of kiwellin (Act d 5).

Discussion and conclusion

Kiwellin has been identified as a plant defense-related protein. Interestingly, many plant allergens are biodefense-related proteins belonging to the pathogenesis-related protein family. Kiwellin, which was discovered to be a transdermal sensitizing antigen, might also be categorized as a biodefense-related protein. This study is the first to identify kiwellin (Act d 5) as a percutaneously sensitizing kiwifruit allergen in a mouse model.

Influence of high-intensity ultrasound on the IgE binding capacity of Act d 2 allergen, secondary structure, and In-vitro digestibility of kiwifruit proteins

Kiwifruit can trigger allergic reactions that can lead to death, causing public health concerns worldwide. In the present study, we treated kiwifruit samples with high-intensity ultrasound (20 kHz, 400 W, 50% duty cycle) for 0 to 16 min to evaluate its effect on the IgE binding capacity of kiwifruit allergen Act d 2, secondary structure and in-vitro digestibility of kiwifruit proteins. The changes in the protein solubility and microstructures of kiwifruit were also analyzed. The results showed that treatment with powerful ultrasound caused a significant disruption in the microstructure of kiwifruit tissues, leading to the changes in the secondary structures of proteins, including a loss of alpha-helixes and an increase in beta-sheet structures. These structural changes were due to the ultrasound treatment, especially 16 min of treatment, resulted in a 50% reduction in Act d 2 allergen content and significantly improved in-vitro digestibility up to 62% from the initial level of 35%. Furthermore, the solubility of the total proteins present in kiwifruit samples was significantly decreased by 20% after 16-min ultrasound processing. The results of this work showed that high-intensity ultrasound treatment has a potential application in reducing the allergenicity of kiwifruit or related products.

Structural responses of kiwifruit allergen Act d 2 to thermal and electric field stresses based on molecular dynamics simulations and experiments

Kiwifruit is considered to be the most common plant-based food causing allergic reactions, after peanuts, soybeans, and wheat.

The nutritional and health attributes of kiwifruit: a review

PURPOSE

To describe the nutritional and health attributes of kiwifruit and the benefits relating to improved nutritional status, digestive, immune and metabolic health. The review includes a brief history of green and gold varieties of kiwifruit from an ornamental curiosity from China in the 19th century to a crop of international economic importance in the 21st century; comparative data on their nutritional composition, particularly the high and distinctive amount of vitamin C; and an update on the latest available scientific evidence from well-designed and executed human studies on the multiple beneficial physiological effects. Of particular interest are the digestive benefits for healthy individuals as well as for those with constipation and other gastrointestinal disorders, including symptoms of irritable bowel syndrome. The mechanisms of action behind the gastrointestinal effects, such as changes in faecal (stool) consistency, decrease in transit time and reduction of abdominal discomfort, relate to the water retention capacity of kiwifruit fibre, favourable changes in the human colonic microbial community and primary metabolites, as well as the naturally present proteolytic enzyme actinidin, which aids protein digestion both in the stomach and the small intestine. The effects of kiwifruit on metabolic markers of cardiovascular disease and diabetes are also investigated, including studies on glucose and insulin balance, bodyweight maintenance and energy homeostasis.

CONCLUSIONS

The increased research data and growing consumer awareness of the health benefits of kiwifruit provide logical motivation for their regular consumption as part of a balanced diet. Kiwifruit should be considered as part of a natural and effective dietary strategy to tackle some of the major health and wellness concerns around the world.

Fixed Food Eruption Caused by Actinidia arguta (Hardy Kiwi): A Case Report and Literature Review

Fixed drug eruption (FDE) is a common hypersensitivity reaction characterized by recurrent, well-circumscribed, erythematous patches that arise at the same site as a result of systemic drug exposure. However, fixed food eruption (FFE), a lesion triggered by food ingestion, is a rare allergy that was first defined in 1996. Based on their anti-inflammatory and anti-oxidant properties, the fruit and leaves of Actinidia arguta, the hardy kiwi, are widely consumed across Korea, Japan, and China. This report describes the first case of FFE caused by hardy kiwi leaves, known as Daraesun in Korean, confirmed by oral provocation tests and skin biopsy.

Water soluble extracts from Actinidia arguta, PG102, attenuates house dust mite-induced murine atopic dermatitis by inhibiting the mTOR pathway with Treg generation

ETHNOPHARMACOLOGICAL RELEVANCE

Actinidia arguta is widespread in northeastern Asia, being found in Siberia, Korea, Japan, and northern China. These fruits have been documented to regulate the uncontrolled heat of body resulting in various allergic diseases in the Korean traditional medicine. PG102, a water-soluble extract from an edible fruit, A. arguta, has been previously shown to control various factors involved in allergic pathogenesis.

AIM OF THE STUDY

In this study, we investigated whether PG102 prevents chronic allergic reactions via the generation of Tregs, which play a preventive role in the pathogenesis of allergic disease.

METHODS AND RESULTS

In dust mite extract-induced chronic atopic dermatitis, orally administered PG102 inhibited symptoms of dermatitis, including ear swelling and erythema, and decreased lymphocyte infiltration into the inflamed region. Moreover, PG102 reduced inflammatory T cell responses and increased the expression levels of Foxp3 and other Treg-related genes. PG102 treatment enhanced the induction of CD4+Foxp3+ Tregs from naive CD4+CD62L+ T cells, probably via the inhibition of mTOR activation and the phosphorylation of STAT5 rather than using the TGF-β signaling pathway.

CONCLUSION

PG102 may have potential as an orally active immunosuppressor for preventing chronic inflammatory diseases.

Inhibition of hardy kiwifruit (Actinidia aruguta) ripening by 1-methylcyclopropene during cold storage and anticancer properties of the fruit extract

Hardy kiwifruits (Actinidia arguta) were treated with 20 μl/l 1-methylcyclopropene (1-MCP) for 16 h at 10 °C and subsequently stored at 1 ± 0.5 °C. Anticancer properties of the fruit extracts were tested against five different human cancer cells. The hardy kiwifruits, without 1-MCP treatment, showed increases in both respiration and ethylene production rates during fruit storage. The 1-MCP treatment remarkably inhibited fruit ripening by reducing respiration and ethylene production. Fruits with the 1-MCP treatment could be stored for up to 5 weeks by maintaining higher fruit firmness, ascorbic acid and total phenolic contents compared to the control. The hardy kiwifruit extracts showed anti-proliferative effects to Hep3B and HeLa cells but not to HT29, HepG2 and LoVo cells. These results suggest that the application of 1-MCP at harvest effectively delayed the ripening process of the fruits, and the fruit extract had beneficial effects for the prevention of human cancer growth.

Kiwifruit allergies

While kiwifruit has a high nutritive and health value, a small proportion of the world's population appears to be allergic to the fruit. IgE-mediated kiwifruit allergy is often associated with birch and grass pollinosis as well as with latex allergy. Isolated allergy to kiwifruit is also relatively common and often severe. Eleven green kiwifruit (Actinidia deliciosa cv. Hayward) allergens recognized to date are termed as Act d 1 through Act d 11. Bet v 1 homologue (Act d 8) and profilin (Act d 9) are important allergens in polysensitized subjects, whereas actinidin (Act d 1) is important in kiwifruit monosensitized subjects. Differences in allergenicity have been found among kiwifruit cultivars. Allergy sufferers might benefit from the selection and breeding of low-allergenic kiwifruit cultivars.

Impact of thermal processing and the Maillard reaction on the basophil activation of hazelnut allergic patients

Food allergy, an abnormal immunological response due to sensitization to a food component, has become an important health problem, especially in industrialized countries. The aim of this study was to investigate the impact of thermal processing and glycation on the basophil activation by hazelnut proteins using a basophil activation test. Patients with systemic allergic reactions (SR; n=6) to hazelnut as well as patients with an isolated oral allergy syndrome (OAS; n=4) were investigated. Thermal processing of hazelnut proteins either in the presence or absence of wheat proteins did not result in major changes in the stimulatory activity of the basophils for patients with SR or OAS. For the patients with OAS, incubation of hazelnut proteins with glucose led to complete depletion of the stimulatory activity of the basophils. An increase in stimulatory activity of the basophils for two out of six patients with SR was observed. For the other four patients slight or complete abolition of the stimulatory activity was observed. These results indicate that some patients with SR to hazelnut are at risk when exposed to hazelnut proteins, even in processed foods.

Evaluation of IgE reactivity of active and thermally inactivated actinidin, a biomarker of kiwifruit allergy

Actinidin, an abundant cysteine protease from kiwifruit, is a specific biomarker of isolated allergy to kiwifruit. This study evaluates the IgE-binding properties of biologically active and thermally inactivated actinidin. Employing two different activity assays (caseinolytic assay and zymogram with gelatin) we showed that actinidin obtained from kiwifruit extract under native conditions represents a mixture of inactive and active enzyme. The structural integrity of actinidin was confirmed by SDS-PAGE, Edman degradation, mass fingerprint and Western blot with polyclonal antibodies. Although it was capable of inducing positive skin prick test reactions, we failed to detect IgE reactivity of active actinidin in Western blot with patient sera. Thermally inactivated actinidin exhibited IgE reactivity both in vivo and in vitro, indicating that heat processed kiwifruit products may induce clinical reactivity. These findings imply that apart from the allergenic epitopes on its surface, actinidin also contains hidden epitopes inside the protein which become accessible to IgE upon thermal treatment.

Anti-oxidant effects of kiwi fruit in vitro and in vivo

We previously reported that kiwi fruit is rich in polyphenols and has immunostimulatory activity. Polyphenols are widely known for having anti-oxidant effects. We also revealed potential anti-oxidant effects of kiwi fruit in vivo by oral administration to mice. Here, we compared the anti-oxidant effects of kiwi fruit with those of other fruits in vitro. Then, we examined the inhibitory effects of kiwi fruit on oxidation in the human body. There are two varieties of kiwi fruit, green kiwi and gold kiwi. We also examined variation between these varieties. Comparison of the anti-oxidant effects in vitro demonstrated that kiwi fruit had stronger anti-oxidant effects than orange and grapefruit, which are rich in vitamin C; gold kiwi had the strongest anti-oxidant effects. Kiwi fruit inhibited oxidation of biological substances in the human body. In particular, kiwi fruit may inhibit early lipid oxidation. In this study, kiwi fruit had strong anti-oxidant effects and may prevent the development and deterioration of diseases caused by oxidative stress.

Some nutritional, technological and environmental advances in the use of enzymes in meat products

The growing consumer demand for healthier products has stimulated the development of nutritionally enhanced meat products. However, this can result in undesirable sensory consequences to the product, such as texture alterations in low-salt and low-phosphate meat foods. Additionally, in the meat industry, economical aspects have stimulated researchers to use all the animal parts to maximize yields of marketable products. This paper aimed to show some advances in the use of enzymes in meat processing, particularly the application of the proteolytic enzymes transglutaminase and phytases, associated with nutritional, technological, and environmental improvements.

The effect of digestion and pH on the allergenicity of kiwifruit proteins

It is suggested that patients with oral allergy syndrome (OAS) respond to pepsin-sensitive allergens, and systemic reactors identify pepsin-resistant allergens. We sought to assess the digestibility of kiwifruit proteins in simulated gastric fluid (SGF), and to compare the immunogenicity of the digests in patients with isolated oral and systemic reactions to kiwifruit. In addition, the effect of pH on digestibility of kiwifruit proteins was investigated. The in vitro resistance of kiwifruit proteins to digestion was determined using SGF. G-immunoglobulin (IgE) binding to digested proteins was investigated by Western blotting using sera from children and adults (aged 5-72 yr) with systemic reactions and patients with isolated oral symptoms. To determine whether pH conditions influence digestion of kiwifruit extracts, digestion at pHs 1.5-7 were compared by SDS-PAGE. Patients with systemic reactions showed IgE binding to digestion-resistant allergens, but patients with oral symptoms reacted only to digestion-labile allergens. An increase in pH from 1.5 to 2.5 significantly reduced pepsin breakdown of kiwifruit allergens. Immunoreactive digested protein fragments were detectable by immunoblot but not Coomassie stain. This study confirms a difference in the lability of food allergens recognized by patients with systemic reactions and those with OAS. Pepsin digestion of kiwifruit proteins was impaired by hypoacidic conditions suggesting that patients with hypoacidic gastric conditions are at increased risk of systemic absorption of allergens. The data indicate that commonly used methods for predicting allergenicity of novel proteins using Coomassie stains may be flawed.

Performing IgE serum testing due to bioinformatics matches in the allergenicity assessment of GM crops

Proteins introduced into genetically modified (GM) organisms through genetic engineering must be evaluated for their potential to cause allergic disease under various national laws and regulations. The Codex Alimentarius Commission guidance document (2003) calls for testing of serum IgE binding to the introduced protein if the gene was from an allergenic source, or the sequence of the transferred protein has >35% identity in any segment of 80 or more amino acids to a known allergen or shares significant short amino acid identities. The Codex guidance recognized that the assessment will evolve based on new scientific knowledge. Arguably, the current criteria are too conservative as discussed in this paper and they do not provide practical guidance on serum testing. The goals of this paper are: (1) to summarize evidence supporting the level of identity that indicates potential risk of cross-reactivity for those with existing allergies; (2) to provide example bioinformatics results and discuss their interpretation using published examples of proteins expressed in transgenic crops; and (3) to discuss key factors of experimental design and methodology for serum IgE tests to minimize the rate of false negative and false positive identification of potential allergens and cross-reactive proteins.

Analysis of expressed sequence tags from Actinidia: applications of a cross species EST database for gene discovery in the areas of flavor, health, color and ripening

Background

Kiwifruit (Actinidia spp.) are a relatively new, but economically important crop grown in many different parts of the world. Commercial success is driven by the development of new cultivars with novel consumer traits including flavor, appearance, healthful components and convenience. To increase our understanding of the genetic diversity and gene-based control of these key traits in Actinidia, we have produced a collection of 132,577 expressed sequence tags (ESTs).

Results

The ESTs were derived mainly from four Actinidia species (A. chinensis, A. deliciosa, A. arguta and A. eriantha) and fell into 41,858 non redundant clusters (18,070 tentative consensus sequences and 23,788 EST singletons). Analysis of flavor and fragrance-related gene families (acyltransferases and carboxylesterases) and pathways (terpenoid biosynthesis) is presented in comparison with a chemical analysis of the compounds present in Actinidia including esters, acids, alcohols and terpenes. ESTs are identified for most genes in color pathways controlling chlorophyll degradation and carotenoid biosynthesis. In the health area, data are presented on the ESTs involved in ascorbic acid and quinic acid biosynthesis showing not only that genes for many of the steps in these pathways are represented in the database, but that genes encoding some critical steps are absent. In the convenience area, genes related to different stages of fruit softening are identified.

Conclusion

This large EST resource will allow researchers to undertake the tremendous challenge of understanding the molecular basis of genetic diversity in the Actinidia genus as well as provide an EST resource for comparative fruit genomics. The various bioinformatics analyses we have undertaken demonstrates the extent of coverage of ESTs for genes encoding different biochemical pathways in Actinidia.

Identification and characterisation of acidic and novel basic forms of actinidin, the highly abundant cysteine protease from kiwifruit

Actinidin is a cysteine protease found in Actinidia Lindl. (kiwifruit) species that affects the nutraceutical properties, processing characteristics and allergenicity of the fruit. Given the increased consumption of kiwifruit worldwide and the release of new varieties from different Actinidia species, the expression of actinidin mRNA and protein in a range of kiwifruit tissues was examined. Ten different actinidin mRNAs were identified encoding mature proteins of similar molecular weight (~24 kDa), but with predicted pIs ranging from acidic (pI 3.9) to basic (pI 9.3). In A. deliciosa 'Hayward' (green-fleshed kiwifruit) and A. chinensis 'Hort16A' and EM4 (gold-fleshed kiwifruit), actinidin mRNAs for acidic and basic proteins were expressed at comparable levels throughout ripening. Actinidin mRNA expression was highest in fruit at harvest, expression decreased as fruit ripened and was much lower in the core compared with outer pericarp tissue. Two-dimensional gel electrophoresis, combined with western analysis and liquid chromatography mass spectrometry (LC-MS) identified low levels of a novel basic actinidin protein in ripe A. deliciosa and A. chinensis fruit. Extremely high levels of an acidic actinidin protein were detected in A. deliciosa fruit and EM4, but this acidic protein appeared to be absent in 'Hort16A', the most important commercial cultivar of A. chinensis. Analyses on native gels indicated that both the basic and acidic actinidin isoforms in A. deliciosa were active cysteine proteases. Immunolocalisation showed that actinidin was present in small cells, but not large cells in the outer pericarp of mature A. deliciosa fruit at harvest. Within the small cells, actinidin was localised diffusely in the vacuole, associated with the plasma membrane, and in a layer in the plastids near starch granules. The presence of multiple forms of actinidin and varying protein levels in fruit will impact on the ability to breed new kiwifruit varieties with altered actinidin levels.

Fruits of the actinidia genus

Kiwifruit is the most well-known crop in the genus Actinidia. Although Actinidia fruit sales in the international market are dominated by a single kiwifruit cultivar Actinidia deliciosa "Hayward," there are a considerable number of cultivars and selections in the genus that have widely diverse shape, size, and hairiness. They also offer a wide variation in sensory attributes such as flesh color, flavor, and taste, and in nutritional attributes such as the vitamin C level and carotenoid content. The level of actinidin, which is a cysteine protease in kiwifruit, also varies greatly among cultivars. This chapter reviews available information related to several important components, allergenic properties, and health benefits of Actinidia fruits.