The clinical impact of cross-reactions between allergens on allergic skin diseases.

PURPOSE OF REVIEW: The route of allergen sensing via the skin appears to influence the immune system towards mounting a type 2 response, especially in genetically predisposed individuals. Allergens recognized this way may derive from microbial, animal, food, or other plant sources and trigger atopic dermatitis. Allergens can be grouped into families depending on their structure and function, harboring significant structural and sequence similarities. Cross-reactivity between allergens is believed to arise as a consequence, and to underlie the development of further atopic diseases. RECENT FINDINGS: Especially for the plant allergens of the families of PR10-related proteins and profilins, immune cross-reactions have been described. Actual studies support that food and pollen allergens can aggravate skin lesions in patients suffering from atopic dermatitis. Further on, allergens derived from air-borne or skin-borne fungi belong to common allergen families and bear cross-reactivity potential. Cross-reactivity to human homologous proteins, so-called autoallergens, is discussed to contribute to the chronification of atopic dermatitis. SUMMARY: Due to high evolutionary conservation, allergic reactions can be triggered by highly homologous members of allergen families on the humoral as well as on the cellular level.

Identification of Genetic Locus Underlying Easy Dehulling in Rice-Tartary for Easy Postharvest Processing of Tartary Buckwheat.

As a highly nutritious crop, Tartary buckwheat (Fagopyrum tartaricum) strongly adapts and grows in adverse environments and is widely grown in Asia. However, its flour contains a large proportion of the hull that adheres to the testa layer of the groats and is difficult to be removed in industrial processing. Fortunately, rice-Tartary, with the loose and non-adhering hull, provides potentiality of improving Tartary buckwheat that can dehull easily. Here, we performed high-throughput sequencing for two parents (Tartary buckwheat and rice-Tartary) and two pools (samples from the F2 population) and obtained 101 Gb raw sequencing data for further analysis. Sequencing reads were mapped to the reference genome of Tartary buckwheat, and a total of 633,256 unique SNPs and 270,181 unique indels were found in these four samples. Then, based on the Bulked Segregant Analysis (BSA), we identified a candidate genetic region, containing 45 impact SNPs/indels and 36 genes, that might underly non-adhering hull of rice-Tartary and should have value for breeding easy dehulling Tartary buckwheat.

Silkworm dropping extract regulates food allergy symptoms via inhibition of Th2-related responses in an ovalbumin-induced food allergy model.

BACKGROUND: Silkworm droppings have long been used in traditional medicine to remedy allergic itching, palsy, blood circulation problems, and arthritis in Asian countries. To investigate the anti-allergic effect of silkworm dropping extract (SDE) and its mechanism, we used a mouse model of food allergy induced by ovalbumin (OVA). RESULTS: SDE ameliorated the symptoms of OVA-induced food allergies, and the levels of T helper 2 (Th2)-related cytokines [such as interleukin (IL)-4, IL-5, IL-10, and IL-13] were found to be significantly decreased in both the spleen and mesenteric lymph nodes by SDE. Furthermore, SDE treatment directly inhibited OVA permeation, IL-4 production, and degranulation of mast cells; in contrast, immunoglobulin E (IgE) production from B cells was not affected. CONCLUSION: These results suggest that SDE has potential anti-allergic activities, and SDE may be useful in the treatment/prevention of allergic disorders such as food allergies, serving as therapeutic agents. © 2019 Society of Chemical Industry.

Anti-Food Allergic Activity of Sulfated Polysaccharide from Gracilaria lemaneiformis is Dependent on Immunosuppression and Inhibition of p38 MAPK.

Polysaccharides from Gracilaria lemaneiformis in particular possess various bioactive functions, but their antiallergic activity remains incompletely defined. Sulfated polysaccharide from Gracilaria lemaneiformis (GLSP) was obtained by water extraction and ethanol precipitation followed by column chromatography. BALB/c mice, RBL-2H3, and KU812 cells were used for verifying the anti food allergic activity of GLSP. According to the results of mice experiment, GLSP was able to alleviate allergy symptoms, to reduce TM-specific IgE and IgG1, to suppress Th2 cell polarization, and to promote the function of regulatory T (Treg) cells. In addition, GLSP had the ability to inhibit the function of RBL-2H3 cells. Furthermore, GLSP inhibited the activation of KU812 via suppression of p38 mitogen-activated protein kinase (MAPK). In conclusion, immunosuppression as well as the reduction in the level of p38 MAPK may contribute to GLSP's putative activity against food allergy. GLSP may be used as a functional food component for allergic patients.

Polymorphisms affecting vitamin D-binding protein modify the relationship between serum vitamin D (25[OH]D3) and food allergy.

BACKGROUND: There is evolving evidence that vitamin D insufficiency may contribute to food allergy, but findings vary between populations. Lower vitamin D-binding protein (DBP) levels increase the biological availability of serum vitamin D. Genetic polymorphisms explain almost 80% of the variation in binding protein levels. OBJECTIVE: We sought to investigate whether polymorphisms that lower the DBP could compensate for adverse effects of low serum vitamin D on food allergy risk. METHODS: From a population-based cohort study (n = 5276) we investigated the association between serum 25-hydroxyvitamin D3 (25[OH]D3) levels and food allergy at age 1 year (338 challenge-proven food-allergic and 269 control participants) and age 2 years (55 participants with persistent and 50 participants with resolved food allergy). 25(OH)D3 levels were measured using liquid chromatography-tandem mass spectrometry and adjusted for season of blood draw. Analyses were stratified by genotype at rs7041 as a proxy marker of DBP levels (low, the GT/TT genotype; high, the GG genotype). RESULTS: Low serum 25(OH)D3 level (≤50 nM/L) at age 1 years was associated with food allergy, particularly among infants with the GG genotype (odds ratio [OR], 6.0; 95% CI, 0.9-38.9) but not in those with GT/TT genotypes (OR, 0.7; 95% CI, 0.2-2.0; P interaction = .014). Maternal antenatal vitamin D supplementation was associated with less food allergy, particularly in infants with the GT/TT genotype (OR, 0.10; 95% CI, 0.03-0.41). Persistent vitamin D insufficiency increased the likelihood of persistent food allergy (OR, 12.6; 95% CI, 1.5-106.6), particularly in those with the GG genotype. CONCLUSIONS: Polymorphisms associated with lower DBP level attenuated the association between low serum 25(OH)D3 level and food allergy, consistent with greater vitamin D bioavailability in those with a lower DBP level. This increases the biological plausibility of a role for vitamin D in the development of food allergy.

Is Low Vitamin D Status A Risk Factor For Food Allergy? Current Evidence And Future Directions.

Studies from several countries have reported an association between latitudes further from the equator and proxy markers of food allergy prevalence. As latitudes further from the equator are associated with lower sun exposure and vitamin D status (VDS), it has been proposed that low VDS may be a risk factor for food allergy. A range of basic science evidence supports the biological plausibility of this hypothesis; and recent work has identified a cross sectional association between low VDS and challenge proven food allergy in infants. Overall, however, the evidence regarding the relationship between VDS and food allergy remains controversial and the limited longitudinal data are discouraging. In this review we consider the evidence for and against low VDS as a risk factor for food allergy and discuss the possibility that other factors (including genetic variables) may contribute to the inconsistent nature of the available observational evidence. We then discuss whether genetic and/or environmental factors may modify the potential influence of VDS on food allergy risk. Finally, we argue that given the rising burden of food allergy, the balance of available evidence regarding the potential relevance of VDS to this phenomenon, and the inherent limitations of the existing observational data, there is a compelling case for conducting randomised clinical trials of vitamin D supplementation for the prevention of food allergy during early life.

Maternal and postnatal dietary probiotic supplementation enhances splenic regulatory T helper cell population and reduces ovalbumin allergen-induced hypersensitivity responses in mice.

Neonatal to early childhood is the critical period for establishing a balance of T helper 1 (Th1) versus T helper 2 (Th2) cellular immunity within the gut, which is strongly influenced by the source and establishment of gut microflora. Probiotic administration has been shown to attenuate Th2-biased cellular immunity and predisposition to food allergies. To test this hypothesis we provided ad libitum a probiotic-supplemented (Primalac 454 Feed Grade Microbials) or control diet to lactating dams with suckling pups and weaned pups until 10 weeks of age. Weaned mice were sensitized/challenged with egg allergen ovalbumin, saline or adjuvant at 6, 8 and 10 weeks of age. At 3, 6, 8 and 10 weeks, fecal samples were collected for microbial analysis, while blood samples were analyzed for ovalbumin-IgE and total plasma IgE levels. At termination, splenic T helper cell lymphocyte population subtypes were determined using FACS analysis and Th1/Th2/Th17 gene expression by PCR array. At 21 days of age, pups suckled by lactating dams fed the probiotic supplemented diet had significantly enhanced Lactobacillus acidophilus fecal counts compared to controls. Moreover, mice fed the probiotic supplemented diet had enhanced splenic naturally occurring and induced regulatory T cell populations, enhanced TGFß gene expression and reduced expression of allergic mediator IL13 compared to controls. These results provide evidence that early probiotic supplementation may provide host protection from hypersensitivity reactions to food allergens by attenuating food allergen inflammatory responses.

Early introduction of fish decreases the risk of eczema in infants.

BACKGROUND: Atopic eczema in infants has increased in western societies. Environmental factors and the introduction of food may affect the risk of eczema. AIMS: To investigate the prevalence of eczema among infants in western Sweden, describe patterns of food introduction and assess risk factors for eczema at 1 year of age. METHODS: Data were obtained from a prospective, longitudinal cohort study of infants born in western Sweden in 2003; 8176 families were randomly selected and, 6 months after the infant's birth, were invited to participate and received questionnaires. A second questionnaire was sent out when the infants were 12 months old. Both questionnaires were completed and medical birth register data were obtained for 4921 infants (60.2% of the selected population). RESULTS: At 1 year of age, 20.9% of the infants had previous or current eczema. Median age at onset was 4 months. In multivariable analysis, familial occurrence of eczema, especially in siblings (OR 1.87; 95% confidence interval (CI) 1.50 to 2.33) or the mother (OR 1.54; 95% CI 1.30 to 1.84), remained an independent risk factor. Introducing fish before 9 months of age (OR 0.76; 95% CI 0.62 to 0.94) and having a bird in the home (OR 0.35; 95% CI 0.17 to 0.75) were beneficial. CONCLUSIONS: One in five infants suffer from eczema during the first year of life. Familial eczema increased the risk, while early fish introduction and bird keeping decreased it. Breast feeding and time of milk and egg introduction did not affect the risk.

Risk factors for the development of food allergy.

Both genetic and environmental factors seem to predispose to the development of food allergy. A most notable factor is diet, particularly during infancy. Possible other factors include maternal diet during pregnancy and lactation, birth by cesarean section, exposure to tobacco smoke, multivitamin supplementation, and intake of antacids. It is important to identify and control such risk factors to reduce the development of food allergy.

Breastfeeding and introduction of solid foods in Swedish infants: the All Babies in Southeast Sweden study.

The aim of this report is to describe breastfeeding duration and introduction of foods in Swedish infants born 1997-9, in relation to current recommendations. A secondary aim is to examine breastfeeding duration and introduction of certain allergenic foods in allergy-risk families (for whom allergy-preventive advice has been issued). Out of 21,700 invited infants, screening questionnaires were completed for 16,070 infants after delivery. Parents to 11,081 infants completed a follow-up questionnaire regarding breastfeeding and introduction of foods and 9849 handed in detailed food diaries at 1 year of age. The percentages of infants who were exclusively breast-fed at 3, 6 and >or=9 months of age were 78.4, 10.1 and 3.9, respectively. The corresponding percentages for partial breastfeeding were 87.8, 68.9 and 43.6. Gluten-containing foods were introduced to 66% of infants between 4 and 6 months, as recommended at the time of the study, and one-quarter had stopped breastfeeding when gluten was introduced. More than 90% of parents introduced the first sample of solid food during months 4-6, as recommended. Fish and eggs had been introduced during the first year in 43% and 29%, respectively, of infants with atopic heredity. Exclusive breastfeeding duration and time of introduction of solid foods, including gluten, seemed to have been in line with Swedish recommendations at the time, although gluten was often introduced late, and not during ongoing breastfeeding as recommended. The adherence to allergy-preventive advice was less than optimal in infants with atopic heredity.

Clinical update on peanut allergy.

BACKGROUND: Peanut allergy is common, potentially severe, and there has been a recent surge in clinical investigation of this important food allergen. OBJECTIVE: To provide the reader with a clinically oriented update on peanut allergy. DATA SOURCES: English language articles were selected from PubMed searches (search terms: peanut allergy, food allergy, anaphylaxis) and selected abstracts with a bias toward recent (3 years) studies judged to have immediate, practical clinical implications. RESULTS: Peanut allergy is an increasing problem in western diets that include this food. Both genetic and environmental factors influences the expression of this allergy. The at-risk subject is an atopic individual, with heightened risk for those with atopic dermatitis and/or other food allergies. The allergy is long-lived for most, may increase slightly in severity over time, but approximately 20% of young children will develop tolerance. Parameters that may identify the subset likely to achieve tolerance have been identified. Several large studies have determined laboratory parameters (skin tests, peanut-specific serum immunoglobulin E concentrations) with excellent predictive value (>95%) to diagnose current clinical reactivity or tolerance, although oral food challenges are necessary for a definitive diagnosis. Numerous practical lessons concerning management (avoidance, treatment, and prevention) have been identified. CONCLUSIONS: Recent studies provide the clinician with an armament of improved diagnostic and treatment modalities for peanut allergy. Studies are underway that are likely to provide more definitive therapies in the near future.

Genetics and specific immune response in allergy to birch pollen and food: evidence of a strong, positive association between atopy and the HLA class II allele HLA-DR7.

BACKGROUND: In some geographic areas birch pollen represents the most prominent cause for airborne allergic diseases. Up to 70% of patients allergic to birch pollen are hypersensitive to fruits, especially apples. Associations have been found, in some instances, with a sensitivity to aeroallergens and HLA class II genes. OBJECTIVES: We investigated whether susceptibility or resistance to birch pollen allergy with and without food allergy was associated with HLA class II genes. METHODS: Blood samples were obtained from 2 groups of unrelated European-born white adults: 42 atopic patients (31 of them with asthma) and 42 healthy control subjects with no personal or familial history of asthma or atopy. Their antibody responses to birch pollen, apples, grass, and weed pollens were evaluated by skin tests, RASTs, and immunoprints. Genomic DNA was extracted from PBLs. The exons of DQA1, DQB1, DRB1, and DPB1 genes were selectively amplified by using the PCR method. Genotyping was carried out by digestion of the amplified DNA products with allele-specific endonucleases (PCR-RFLP), which recognize allelic variations in the polymorphic exon. RESULTS: We found no significant differences in the frequency of DPB1 alleles between patients and control subjects. HLA class II DR4 and/or DR7 alleles were present in 42.6% of the patients and in only 2.4% of the healthy subjects. These results confirm a previous study of a group of polysensitized atopic patients, which showed that DR4 and DR7 alleles were rare in healthy control subjects and frequently observed in atopic subjects with or without concomitant asthma. CONCLUSION: We conclude that the allele HLA-DR7 is significantly involved in the presentation of apple and pollen allergens. However, we suggest that this susceptibility is more related to atopy than to specific responses to allergens.