Kiwifruit Allergy in Children: Characterization of Main Allergens and Patterns of Recognition

Evaluation of Allergic Reactions and Tolerance with Fruit and Vegetable Allergy in Children

INTRODUCTION

Despite the increasing prevalence of fruit and vegetable allergies in childhood over the past decades, the clinical course of reaction types and tolerance remain unclear. Our aim was to evaluate the clinical course, demographic characteristics, and tolerance rate of allergic reactions induced by fruits or vegetables.

METHODS

We conducted a retrospective, descriptive, cross-sectional study on patients who presented with suspected allergic reactions to fruit or vegetables. We used patient records to identify demographic data, skin prick test, prick-to-prick test, and oral food challenge test results and laboratory findings.

RESULTS

The study included 78 children with a median age of 61.5 months. Class 1 and 2 allergies were found in 65 and 13 cases, respectively. The most common allergens were potato (21.8%), banana (15.4%), peach (14.1%), and tomato (12.8%). Clinical symptoms included urticaria (75.6%), oral allergy syndrome (15.4%), angioedema (7.7%), and anaphylaxis (1.3%). Thirteen children achieved tolerance, while 61.7% did not. The median time to tolerance was 13.5 months after diagnosis, with a minimum of 9 months. Significant differences in reaction type, clinical presentation, pan-allergy to aeroallergens, and serum total IgE levels were found between the tolerant and non-tolerant groups (p = 0.006, 0.009, 0.005, and 0.001, respectively).

CONCLUSION

This is the first study to provide guidance on the tolerance rate and resolution time of fruit and vegetable allergies based on demographic and diagnostic parameters. Further research is needed to deepen our understanding of fruit and vegetable allergy.

Kiwifruit's Allergy in Children: What Do We Know?

Kiwifruit allergy is an emerging pathological condition in both general and pediatric populations with a wide range of symptoms linked to variable molecular patterns, justifying systemic and cross-reactions with other allergens (i.e., latex, pollen, and fruit). Skin prick test (SPT), specific serum IgE (Act d 1, Act d 2, Act d 5, Act d 8, and Act d 10) directed against five out of thirteen molecular allergens described in the literature, and oral test challenge with kiwifruit are available for defining diagnosis. The management is similar to that of other food allergies, mostly based on an elimination diet. Although kiwi allergy has been on the rise in recent years, few studies have evaluated the clinical characteristics and methods of investigating this form of allergy. Data collected so far show severe allergic reaction to be more frequent in children compared to adults. Therefore, the aim of this review is to collect the reported clinical features and the available association with specific molecular patterns of recognition to better understand how to manage these patients and improve daily clinical practice.

Features of Molecular Sensitisation Profile in Infants with Risk of Allergic Diseases

Background. For now, there is little data on sensitivity features to specific allergen antigens in infants with initial allergy manifestations. Objective. The aim of the study is to determine the features of the primary molecular sensitisation profile in infants with risk of atopic disease according to their postnatal age. Methods. Full-term infants with burdened familial allergic history and/or skin/gastrointestinal allergy symptoms were examined: Group 1 — 50 children, age — 2.0 [1.0–3.0] months; Group 2 — 35 children, age — 9.0 [8.0–11.0] months. Results. The hereditary atopy risk was observed in 74% of cases (37/50) in Group 1 and in 71% of cases (25/35) in Group 2. 38% of children (19/50) in Group 1 were breastfed, in Group 2 — 60% of children (21/35). Supplemental feeding was implemented in 5.5 [5.0–6.0] months. Sensitisation was reported in 10% and 37% of cases respectively. Children of Group 1 were sensitised to food allergen antigens: cow's milk/meat (Bos d 6, Bos d 8), egg-white (Gal d 1, Gal d 2, Gal d 3), soybeans (Gly m 6), shrimps (Pen m 4); airborne allergens: house dust mite (Blo t 5, Der h 10), Anisakidae (Ani s 3), cockroach (Bla g 7). Children of Group 2 were sensitised to food allergen antigens: cow's milk (Bos d 6), egg-white (Gal d 1, Gal d 2), soybeans (Gly m 6), peanut (Ara h 1, Ara h 2, Ara h 6), kiwi (Act d 1), corn (Tri a 19); airborne allergens: cat (Fel d 1, Fel d 4), birch pollen (Bet v 1). Polyvalent sensitisation was revealed in 4% and 6% of cases, respectively. Conclusion. Infants have much wider range of allergens to which they are sensitive than it is commonly believed. Beside obligate food allergens, sensitisation can be caused by airborne allergens: house dust mites, epidermal, birch pollen; cross-reactive component — tropomyosin.

A new approach for activation of the kiwifruit cysteine protease for usage in in-vitro testing

Actinidin (Act d 1), a highly abundant cysteine protease from kiwifruit, is one of the major contributors to the development of kiwifruit allergy. Many studies have focused on the optimization of Act d 1 purification and its role in the development of food allergies. Testing on cell culture monolayers is a common step in the elucidation of food allergen sensitization. In the case of cysteine proteases, an additional activation step with L-cysteine is required before the testing. Hence, we aimed to evaluate whether L-cysteine already present in commonly used cell culture media would suffice for Act d 1 activation. Successfully activated Act d 1 (98.1% of proteolytic activity, as compared to L-cysteine activated Act d 1) was further tested in two commonly used 2D model systems (Caco-2 and HEK293 cells) to evaluate its role on the mRNA expression of cytokines involved in the innate immunity (IL-1β, IL-6, TNFα, TSLP). Furthermore, the contribution of Act d 1 in the promotion of inflammation through regulation of inducible nitric oxide synthase (iNOS) mRNA expression was also examined. These results demonstrate that activation of cysteine proteases can be achieved without previous enzyme incubation in L-cysteine -containing solution. Act d 1 incubated in cell culture medium was able to modulate gene expression of pro-inflammatory cytokines when tested on two model systems of the epithelial barrier.

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 Kiwifruit Allergen Act d 1 Activates NF-κB Signaling and Affects mRNA Expression of TJ Proteins and Innate Pro-Allergenic Cytokines

Impairment of the intestinal barrier is one of the key events in the initiation of the sensitization process in food allergy. The aim of this study was to explore the effects of kiwifruit allergen Act d 1 on intestinal permeability and tight junction protein (TJP) gene expression in vivo and to explore its potential to activate the NF-ĸB signaling pathway and to regulate expression of epithelial pro-allergenic cytokines. Influences of Act d 1 on TJP gene expression and pro-allergenic cytokines in the mouse intestine was analyzed by qPCR upon allergen administration by oral gavage. The effect on the in vivo intestinal permeability was assessed in ELISA by measuring the translocation of β-lactoglobulin (BLG) into circulation. The capacity of Act d 1 to activate the NF-ĸB pathway was tested in HEK293 cells by fluorescent microscopy and flow cytometry. Administration of Actinidin (Act d 1) increased intestinal permeability to the BLG. This was accompanied by changes in gene expression of TJP mRNA and pro-allergenic cytokines IL-25, IL-33, and thymic stromal lymphopoietin (TSLP) compared to the control. Act d 1 reduced TEER of the HEK293 monolayer, was positive in an NF-ĸB-reporter HEK293 cell assay, and induced secretion of TSLP. These findings shed more light on the molecular events in the sensitization process of kiwifruit but possibly also of other protease food allergens.

A Comprehensive Review on Kiwifruit Allergy: Pathogenesis, Diagnosis, Management, and Potential Modification of Allergens Through Processing

Kiwifruit is rich in bioactive components including dietary fibers, carbohydrates, natural sugars, vitamins, minerals, omega-3 fatty acids, and antioxidants. These components are beneficial to boost the human immune system and prevent cancer and heart diseases. However, kiwifruit is emerging as one of the most common elicitors of food allergies worldwide. Kiwifruit allergy results from an abnormal immune response to kiwifruit proteins and occur after consuming this fruit. Symptoms range from the oral allergy syndrome (OAS) to the life-threatening anaphylaxis. Thirteen different allergens have been identified in green kiwifruit and, among these allergens, Act d 1, Act d 2, Act d 8, Act d 11, and Act d 12 are defined as the "major allergens." Act d 1 and Act d 2 are ripening-related allergens and are found in abundance in fully ripe kiwifruit. Structures of several kiwifruit allergens may be altered under high temperatures or strong acidic conditions. This review discusses the pathogenesis, clinical features, and diagnosis of kiwifruit allergy and evaluates food processing methods including thermal, ultrasound, and chemical processing which may be used to reduce the allergenicity of kiwifruit. Management and medical treatments for kiwifruit allergy are also summarized.