Sialic acid-modified der p 2 allergen exerts immunomodulatory effects on human PBMCs

Background

House dust mite extract-based allergen immunotherapy (AIT) to treat house dust mite allergy is substantially effective but still presents some safety and efficacy concerns that warrant improvement. Several major allergen-based approaches to increase safety and efficacy of AIT have been proposed. One of them is the use of the group 2 allergen, Der p 2.

Objective

We sought to investigate the immunomodulatory effects of sialic acid-modified major allergen recombinant Der p 2 (sia-rDer p 2) on PBMCs from healthy volunteers.

Methods

We activated PBMCs with anti-CD3/CD28 antibodies and incubated them at 37°C for 6 days in the presence or absence of either native rDer p 2 or α2-3 sialic acid-modified rDer p 2 (sia-rDer p 2). We assessed the changes in CD4+ T-cell activation and proliferation by flow cytometry and changes in T-lymphocyte cytokine production in cell culture supernatant by ELISA.

Results

We observed that PBMCs treated with sia-rDer p 2 presented with a markedly decreased expression of CD69 and an increased abundance of LAG-3+ lymphocytes compared with cells treated with rDer p 2. Moreover, PBMCs treated with sia-rDer p 2 showed a reduced production of IL-4, IL-13, and IL-5 and displayed a higher IL-10/IL-5 ratio compared with rDer p 2-treated PBMCs.

Conclusions

We demonstrate that sia-rDer p 2 might be a safer option than native rDer p 2 for Der p 2-specific AIT. This is most relevant in the early phase of AIT that is often characterized by heightened TH2 responses, because sia-rDer p 2 does not enhance the production of TH2 cytokines.

Unique allergen-specific human IgE monoclonal antibodies derived from patients with allergic disease

Introduction

Allergic reactions are mediated by human IgE antibodies that bind to and cross-link allergen molecules. The sites on allergens that are recognized by IgE antibodies have been difficult to investigate because of the paucity of IgE antibodies in a human serum. Here, we report the production of unique human IgE monoclonal antibodies to major inhaled allergens and food allergens that can be produced at scale in perpetuity.

Materials and methods

The IgE antibodies were derived from peripheral blood mononuclear cells of symptomatic allergic patients, mostly children aged 3-18 years, using hybridoma fusion technology. Total IgE and allergen-specific IgE was measured by ImmunoCAP. Their specificity was confirmed through ELISA and immunoblotting. Allergenic potency measurements were determined by ImmunoCAP inhibition. Biological activity was determined in vitro by comparing β-hexosaminidase release from a humanized rat basophilic cell line.

Results

Human IgE monoclonal antibodies (n = 33) were derived from 17 allergic patients with symptoms of allergic rhinitis, asthma, atopic dermatitis, food allergy, eosinophilic esophagitis, or red meat allergy. The antibodies were specific for five inhaled allergens, nine food allergens, and alpha-gal and had high levels of IgE (53,450-1,702,500 kU/L) with ratios of specific IgE to total IgE ranging from <0.01 to 1.39. Sigmoidal allergen binding curves were obtained through ELISA, with low limits of detection (<1 kU/L). Allergen specificity was confirmed through immunoblotting. Pairs of IgE monoclonal antibodies to Ara h 6 were identified that cross-linked after allergen stimulation and induced release of significant levels of β-hexosaminidase (35%-80%) from a humanized rat basophilic cell line.

Conclusions

Human IgE monoclonal antibodies are unique antibody molecules with potential applications in allergy diagnosis, allergen standardization, and identification of allergenic epitopes for the development of allergy therapeutics. The IgE antibody probes will enable the unequivocal localization and validation of allergenic epitopes.

Corrigendum: Biological activity of human IgE monoclonal antibodies targeting Der p 2, Fel d 1, Ara h 2 in basophil mediator release assays

[This corrects the article DOI: 10.3389/fimmu.2023.1155613.].

A European-Japanese study on peach allergy: IgE to Pru p 7 associates with severity

BACKGROUND

Pru p 3 and Pru p 7 have been implicated as risk factors for severe peach allergy. This study aimed to establish sensitization patterns to five peach components across Europe and in Japan, to explore their relation to pollen and foods and to predict symptom severity.

METHODS

In twelve European (EuroPrevall project) and one Japanese outpatient clinic, a standardized clinical evaluation was conducted in 1231 patients who reported symptoms to peach and/or were sensitized to peach. Specific IgE against Pru p 1, 2, 3, 4 and 7 and against Cup s 7 was measured in 474 of them. Univariable and multivariable Lasso regression was applied to identify combinations of parameters predicting severity.

RESULTS

Sensitization to Pru p 3 dominated in Southern Europe but was also quite common in Northern and Central Europe. Sensitization to Pru p 7 was low and variable in the European centers but very dominant in Japan. Severity could be predicted by a model combining age of onset of peach allergy, probable mugwort, Parietaria pollen and latex allergy, and sensitization to Japanese cedar pollen, Pru p 4 and Pru p 7 which resulted in an AUC of 0.73 (95% CI 0.73-0.74). Pru p 3 tended to be a risk factor in South Europe only.

CONCLUSIONS

Pru p 7 was confirmed as a significant risk factor for severe peach allergy in Europe and Japan. Combining outcomes from clinical and demographic background with serology resulted in a model that could better predict severity than CRD alone.

IgE cross-inhibition between Ara h 1 and Ara h 2 is explained by complex formation of both major peanut allergens

BACKGROUND

Surprisingly, IgE cross-reactivity between the major peanut allergens Ara h 1, 2, and 3 has been reported despite very low sequence identities.

OBJECTIVE

We investigated the unexpected cross-reactivity between peanut major allergens.

METHODS

Cross-contamination of purified natural Ara h 1, 2, 3, and 6 was assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Western blot test, liquid chromatography-tandem mass spectrometry (LC-MS/MS), and sandwich enzyme-linked immunosorbent assay (ELISA). IgE cross-reactivity was studied with sera of peanut-allergic patients (n = 43) by ELISA and ImmunoCAP inhibition using both intact natural and recombinant allergens and synthetic peptides representing postulated Ara h 1 and Ara h 2 cross-reactive epitopes.

RESULTS

Both purified nAra h 1 and nAra h 3 were demonstrated to contain small but significant amounts of Ara h 2 and Ara h 6 (<1%) by sandwich ELISA, SDS-PAGE/Western blot analysis, and LC-MS/MS. IgE cross-inhibition between both 2S albumins and Ara h 1 and Ara h 3 was only observed when using natural purified allergens, not recombinant allergens or synthetic peptides. Apparent cross-reactivity was lost when purified nAra h 1 was pretreated under reducing conditions, suggesting that Ara h 2 and Ara h 6 contaminations may be covalently bound to Ara h 1 via disulfide interactions.

CONCLUSION

True cross-reactivity of both peanut 2S albumins with Ara h 1 and Ara h 3 could not be demonstrated. Instead, cross-contamination with small quantities was shown to be sufficient to cause significant cross-inhibition that can be misinterpreted as molecular cross-reactivity. Diagnostic tests using purified nAra h 1 and nAra h 3 can overestimate their importance as major allergens as a result of the presence of contaminating 2S albumins, making recombinant Ara h 1 and Ara h 3 a preferred alternative.

Biological activity of human IgE monoclonal antibodies targeting Der p 2, Fel d 1, Ara h 2 in basophil mediator release assays

Background

Human Immunoglobulin E monoclonal antibodies (hIgE mAb) are unique tools for investigating IgE responses. Here, the biological activity of hIgE mAb, derived from immortalized B cells harvested from the blood of allergic donors, targeting three allergens (Der p 2, Fel d 1 and Ara h 2) was investigated.

Methods

Three Der p 2-, three Fel d 1- and five Ara h 2-specific hIgE mAb produced by human B cell hybridomas, were combined in pairs and used to passively sensitize humanized rat basophilic leukemia cells and compared with sensitization using serum pools. Sensitized cells were stimulated with corresponding allergens (recombinant or purified), allergen extracts or structural homologs, having 40-88% sequence similarity, and compared for mediator (β-hexosaminidase) release.

Results

One, two and eight pairs of Der p 2-, Fel d 1- and Ara h 2-specific hIgE mAb, respectively, produced significant mediator release (>50%). A minimum hIgE mAb concentration of 15-30 kU/L and a minimum antigen concentration between 0.01-0.1 µg/mL were sufficient to induce a pronounced mediator release. Individual sensitization with one Ara h 2-specific hIgE mAb was able to induce crosslinking independently of a second specific hIgE mAb. Der p 2- and Ara h 2-specific mAb showed a high allergen specificity when compared to homologs. Mediator release from cells sensitized with hIgE mAb was comparable to serum sensitization.

Conclusion

The biological activity of hIgE mAb reported here provides the foundation for novel methods of standardization and quality control of allergen products and for mechanistic studies of IgE-mediated allergic diseases, using hIgE mAb.

Estimating the Risk of Severe Peanut Allergy Using Clinical Background and IgE Sensitization Profiles

Background: It is not well-understood why symptom severity varies between patients with peanut allergy (PA). Objective: To gain insight into the clinical profile of subjects with mild-to-moderate and severe PA, and investigate individual and collective predictive accuracy of clinical background and IgE to peanut extract and components for PA severity. Methods: Data on demographics, patient history and sensitization at extract and component level of 393 patients with probable PA (symptoms ≤ 2 h + IgE sensitization) from 12 EuroPrevall centers were analyzed. Univariable and penalized multivariable regression analyses were used to evaluate risk factors and biomarkers for severity. Results: Female sex, age at onset of PA, symptoms elicited by skin contact with peanut, family atopy, atopic dermatitis, house dust mite and latex allergy were independently associated with severe PA; birch pollen allergy with mild-to-moderate PA. The cross-validated AUC of all clinical background determinants combined (0.74) was significantly larger than the AUC of tests for sensitization to extract (0.63) or peanut components (0.54-0.64). Although larger skin prick test wheal size, and higher IgE to peanut extract, Ara h 1 and Ara h 2/6, were associated with severe PA, and higher IgE to Ara h 8 with mild-to-moderate PA, addition of these measurements of sensitization to the clinical background model did not significantly improve the AUC. Conclusions: Models combining clinical characteristics and IgE sensitization patterns can help establish the risk of severe reactions for peanut allergic patients, but clinical background determinants are most valuable for predicting severity of probable PA in an individual patient.

Bee- and Wasp-Venom Sensitization in Schoolchildren of High- and Low-Socioeconomic Status Living in an Urban Area of Indonesia

BACKGROUND

There is not much known about venom allergy in tropical regions. Here, we studied the prevalence of specific IgE (sIgE) and skin prick test (SPT) reactivity and reported sting-related symptoms, in high- and low-socioeconomic status (SES) schoolchildren living in urban city of Makassar in Indonesia.

METHODS

Children from high- (n = 160) and low- (n = 165) SES schools were recruited. Standardized questionnaires were used to record information on allergic disorders as well as sting-related symptoms. Parasitic infection, SPT reactivity, and sIgE to Apis mellifera (bee-venom) as well as Vespula spp. (wasp-venom) were assessed.

RESULTS

SPT reactivity to bee- and wasp-venom was 14.3 and 12.7%, while the prevalence of sIgE was 26.5 and 28.5%, respectively. When SES was considered, prevalence of SPT to bee- and wasp-venom was higher in high-SES than in low-SES schoolchildren (bee: 22.8 vs. 5.7%, p < 0.001; and wasp: 19.6 vs. 5.7%, p < 0.001). Conversely, sIgE to both venoms was lower in high-SES than in low-SES (bee: 19 vs. 34%, p = 0.016; and wasp: 19 vs. 38%, p = 0.003). Furthermore, among SPT positive subjects, considerable proportion had no detectable sIgE to bee- (65.85%) or wasp-venom (66.67%). Altogether the sensitizations were rarely translated into clinical reaction, as only 1 child reported significant local reaction after being stung. No association with parasitic infections was found.

CONCLUSIONS AND CLINICAL RELEVANCE

Sensitization against bee- or wasp-venom is quite prevalent among schoolchildren in Indonesia. The discordance between SPT and sIgE might suggest the direct (non-IgE) effect of venoms in skin reactivity. Recorded sensitizations had poor clinical relevance as they rarely translated into clinical symptoms.

Predicting food allergy: The value of patient history reinforced

Background

EAACI guidelines emphasize the importance of patient history in diagnosing food allergy (FA) and the need for studies investigating its value using standardized allergy‐focused questionnaires.

Objective

To determine the contribution of reaction characteristics, allergic comorbidities and demographics to prediction of FA in individuals experiencing food‐related adverse reactions.

Methods

Adult and school‐age participants in the standardized EuroPrevall population surveys, with self‐reported FA, were included. Penalized multivariable regression was used to assess the association of patient history determinants with “probable” FA, defined as a food‐specific case history supported by relevant IgE sensitization.

Results

In adults (N = 844), reproducibility of reaction (OR 1.35 [95% CI 1.29‐1.41]), oral allergy symptoms (OAS) (4.46 [4.19‐4.75]), allergic rhinitis (AR) comorbidity (2.82 [2.68‐2.95]), asthma comorbidity (1.38 [1.30‐1.46]) and male sex (1.50 [1.41‐1.59]) were positively associated with probable FA. Gastrointestinal symptoms (0.88 [0.85‐0.91]) made probable FA less likely. The AUC of a model combining all selected predictors was 0.85 after cross‐validation. In children (N = 670), OAS (2.26 [2.09‐2.44]) and AR comorbidity (1.47 [CI 1.39‐1.55]) contributed most to prediction of probable FA, with a combined cross‐validation‐based AUC of 0.73. When focusing on plant foods, the dominant source of FA in adults, the pediatric model also included gastrointestinal symptoms (inverse association), and the AUC increased to 0.81.

Conclusions

In both adults and school‐age children from the general population, reporting of OAS and of AR comorbidity appear to be the strongest predictors of probable FA. Patient history particularly allows for good discrimination between presence and absence of probable plant FA.

Association of frequent moisturizer use in early infancy with the development of food allergy

Background

Objectives

Methods

Results

Conclusions

Gut microbiota development during infancy: Impact of introducing allergenic foods

BACKGROUND

The gut microbiota potentially plays an important role in the immunologic education of the host during early infancy.

OBJECTIVE

We sought to determine how the infant gut microbiota evolve during infancy, particularly in relation to hygiene-related environmental factors, atopic disorders, and a randomized introduction of allergenic solids.

METHODS

A total of 1303 exclusively breast-fed infants were enrolled in a dietary randomized controlled trial (Enquiring About Tolerance study) from 3 months of age. In this nested longitudinal study, fecal samples were collected at baseline, with additional sampling of selected cases and controls at 6 and 12 months to study the evolution of their gut microbiota, using 16S ribosomal RNA gene-targeted amplicon sequencing.

RESULTS

In the 288 baseline samples from exclusively breast-fed infant at 3 months, the gut microbiota was highly heterogeneous, forming 3 distinct clusters: Bifidobacterium-rich, Bacteroides-rich, and Escherichia/Shigella-rich. Mode of delivery was the major discriminating factor. Increased Clostridium sensu stricto relative abundance at 3 months was associated with presence of atopic dermatitis on examination at age 3 and 12 months. From the selected cases and controls with longitudinal samples (n = 70), transition to Bacteroides-rich communities and influx of adult-specific microbes were observed during the first year of life. The introduction of allergenic solids promoted a significant increase in Shannon diversity and representation of specific microbes, such as genera belonging to Prevotellaceae and Proteobacteria (eg, Escherichia/Shigella), as compared with infants recommended to exclusively breast-feed.

CONCLUSIONS

Specific gut microbiota characteristics of samples from 3-month-old breast-fed infants were associated with cesarean birth, and greater Clostridium sensu stricto abundance was associated with atopic dermatitis. The randomized introduction of allergenic solids from age 3 months alongside breast-feeding was associated with differential dynamics of maturation of the gut microbial communities.

Cross-reactive carbohydrate determinant-specific IgE obscures true atopy and exhibits ⍺-1,3-fucose epitope-specific inverse associations with asthma

Background

In high-income, temperate countries, IgE to allergen extracts is a risk factor for, and mediator of, allergy-related diseases (ARDs). In the tropics, positive IgE tests are also prevalent, but rarely associated with ARD. Instead, IgE responses to ubiquitous cross-reactive carbohydrate determinants (CCDs) on plant, insect and parasite glycoproteins, rather than to established major allergens, are dominant. Because anti-CCD IgE has limited clinical relevance, it may impact ARD phenotyping and assessment of contribution of atopy to ARD.

Methods

Using an allergen extract-based test, a glycan and an allergen (glyco)protein microarray, we mapped IgE fine specificity among Ugandan rural Schistosoma mansoni (Sm)-endemic communities, proximate urban communities, and importantly in asthmatic and nonasthmatic schoolchildren.

Results

Overall, IgE sensitization to extracts was highly prevalent (43%-73%) but allergen arrays indicated that this was not attributable to established major allergenic components of the extracts (0%-36%); instead, over 40% of all participants recognized CCD-bearing components. Using glycan arrays, we dissected IgE responses to specific glycan moieties and found that reactivity to classical CCD epitopes (core β-1,2-xylose, α-1,3-fucose) was positively associated with sensitization to extracts, rural environment and Sm infection, but not with skin reactivity to extracts or sensitization to their major allergenic components. Interestingly, we discovered that reactivity to only a subset of core α-1,3-fucose-carrying N-glycans was inversely associated with asthma.

Conclusions

CCD reactivity is not just an epiphenomenon of parasite exposure hampering specificity of allergy diagnostics; mechanistic studies should investigate whether specific CCD moieties identified here are implicated in the protective effect of certain environmental exposures against asthma.

Variation in IgE binding potencies of seven Artemisia species depending on content of major allergens

BACKGROUND

Artemisia weed pollen allergy is important in the northern hemisphere. While over 350 species of this genus have been recorded, there has been no full investigation into whether different species may affect the allergen diagnosis and treatment. This study aimed to evaluate the variations in amino acid sequences and the content of major allergens, and how these affect specific IgE binding capacity in representative Artemisia species.

METHODS

Six representative Artemisia species from China and Artemisia vulgaris from Europe were used to determine allergen amino acid sequences by transcriptome, gene sequencing and mass spectrometry of the purified allergen component proteins. Sandwich ELISAs were developed and applied for Art v 1, Art v 2 and Art v 3 allergen quantification in different species. Aqueous pollen extracts and purified allergen components were used to assess IgE binding by ELISA and ImmunoCAP with mugwort allergic patient serum pools and individual sera from five areas in China.

RESULTS

The Art v 1 and Art v 2 homologous allergen sequences in the seven Artemisia species were highly conserved. Art v 3 type allergens in A. annua and A. sieversiana were more divergent compared to A. argyi and A. vulgaris. The allergen content of Art v 1 group in the seven extracts ranged from 3.4% to 7.1%, that of Art v 2 from 1.0% to 3.6%, and Art v 3 from 0.3% to 10.5%. The highest IgE binding potency for most Chinese Artemisia allergy patients was with A. annua pollen extract, followed by A. vulgaris and A. argyi, with A. sieversiana significantly lower. Natural Art v 1-3 isoallergens from different species have almost equivalent IgE binding capacity in Artemisia allergic patients from China.

CONCLUSION AND CLINICAL RELEVANCE

There was high sequence similarity but different content of the three group allergens from different Artemisia species. Choice of Artemisia annua and A. argyi pollen source for diagnosis and immunotherapy is recommended in China.

Frequency of food allergy in school-aged children in eight European countries-The EuroPrevall-iFAAM birth cohort

BACKGROUND

The prevalence of food allergy (FA) among European school children is poorly defined. Estimates have commonly been based on parent-reported symptoms. We aimed to estimate the frequency of FA and sensitization against food allergens in primary school children in eight European countries.

METHODS

A follow-up assessment at age 6-10 years of a multicentre European birth cohort based was undertaken using an online parental questionnaire, clinical visits including structured interviews and skin prick tests (SPT). Children with suspected FA were scheduled for double-blind, placebo-controlled oral food challenges (DBPCFC).

RESULTS

A total of 6105 children participated in this school-age follow-up (57.8% of 10 563 recruited at birth). For 982 of 6069 children (16.2%), parents reported adverse reactions after food consumption in the online questionnaire. Of 2288 children with parental face-to-face interviews and/or skin prick testing, 238 (10.4%) were eligible for a DBPCFC. Sixty-three foods were challenge-tested in 46 children. Twenty food challenges were positive in 17 children, including seven to hazelnut and three to peanut. Another seventy-one children were estimated to suffer FA among those who were eligible but refused DBPCFC. This yielded prevalence estimates for FA in school age between 1.4% (88 related to all 6105 participants of this follow-up) and 3.8% (88 related to 2289 with completed eligibility assessment).

INTERPRETATION

In primary school children in eight European countries, the prevalence of FA was lower than expected even though parents of this cohort have become especially aware of allergic reactions to food. There was moderate variation between centres hampering valid regional comparisons.

Comparative Study of Food Allergies in Children from China, India, and Russia: The EuroPrevall-INCO Surveys

BACKGROUND

A clear understanding of the differences in the epidemiology of food allergy between rural and urban populations may provide insights into the causes of increasing prevalence of food allergy in the developed world.

OBJECTIVE

We used a standardized methodology to determine the prevalence and types of food-specific allergic sensitization and food allergies in schoolchildren from urban and rural regions of China, Russia, and India.

METHODS

The current study is a multicenter epidemiological survey of children recruited from 5 cities in China (Hong Kong and Guangzhou), Russia (Tomsk), and India (Bengaluru and Mysore) and 1 rural county in Southern China (Shaoguan). A total of 35,549 children aged 6 to 11 years from 3 countries participated in this survey. Random samples of children from 3 countries were first screened by the EuroPrevall screening questionnaire. Children with and without a history of adverse reactions to foods were then recruited for the subsequent case-control comparative studies. We determined the prevalence rates of food-specific IgE sensitization and food allergies using the predefined criteria.

RESULTS

The prevalence rates of food-specific IgE sensitization (≥0.7 kU/L) to at least 1 food were 16.6% in Hong Kong, 7.0% in Guangzhou, 16.8% in rural Shaoguan, 8.0% in Tomsk, and 19.1% in India. Using a definition of probable food allergy as reporting allergic symptoms within 2 hours of ingestion of a specific food plus the presence of allergic sensitization to the specific food (positive IgE and/or positive skin prick test result), the prevalence of food allergy was highest in Hong Kong (1.50%), intermediate in Russia (0.87%), and lowest in Guangzhou (0.21%), Shaoguan (0.69%), and India (0.14%). For children recruited from Hong Kong, both sensitization and food allergy were significantly higher in children who were born and raised in Hong Kong when compared with those who were born in mainland China and migrated to Hong Kong, highlighting the importance of early-life exposures in affecting the subsequent development of food sensitization and food allergy.

CONCLUSIONS

There are wide variations in the prevalence of food-specific IgE sensitization and food allergy in the 3 participating countries. Food allergy appears to be less common when compared with developed countries. The variations in the prevalence of food allergen sensitization cannot be explained by the differences in the degree of urbanization. Despite the high prevalence of food-specific IgE sensitization in India and rural China, food allergy is still extremely uncommon. In addition to IgE sensitization, other factors must play important roles resulting in the clinical manifestations of food allergies.

Factors influencing adherence in a trial of early introduction of allergenic food

BACKGROUND

The Enquiring About Tolerance (EAT) study examined whether the early introduction of 6 allergenic foods from 3 months of age in exclusively breastfed infants prevented the development of food allergy. The intervention was effective in the per-protocol analysis for allergy to 1 or more foods and for egg and peanut individually, but only 42% of early introduction group (EIG) children met the per-protocol criteria.

OBJECTIVE

We sought to identify which factors were responsible for nonadherence in the EAT study.

METHODS

Factors influencing adherence within the key early introduction period in the EIG (up to 6 months of age) were divided into enrollment and postenrollment factors, and their association with nonadherence was explored.

RESULTS

In an adjusted analysis, at enrollment, increased maternal age, nonwhite ethnicity, and lower maternal quality of life were independently and significantly associated with overall nonadherence in the EIG. Enrollment eczema and enrollment serum allergen-specific IgE sensitization to 1 or more foods (≥0.1 kU/L) were not related to overall nonadherence. After enrollment, 2 factors were significantly related to EIG overall nonadherence: parent-reported IgE-type symptoms with infant allergenic food consumption by 6 months of age and reported feeding difficulties by 4 months of age.

CONCLUSION

If early introduction of allergenic foods were to be considered a strategy to prevent food allergy, families of nonwhite ethnicity, those with older mothers, and those with infants with reported feeding difficulties or early-onset eczema would benefit from support to promote early and sustained consumption.

Efficacy of the Enquiring About Tolerance (EAT) study among infants at high risk of developing food allergy

BACKGROUND

The Enquiring About Tolerance (EAT) study was a randomized trial of the early introduction of allergenic solids into the infant diet from 3 months of age. The intervention effect did not reach statistical significance in the intention-to-treat analysis of the primary outcome.

OBJECTIVE

We sought to determine whether infants at high risk of developing a food allergy benefited from early introduction.

METHODS

A secondary intention-to-treat analysis was performed of 3 groups: nonwhite infants; infants with visible eczema at enrollment, with severity determined by SCORAD; and infants with enrollment food sensitization (specific IgE ≥0.1 kU/L).

RESULTS

Among infants with sensitization to 1 or more foods at enrollment (≥0.1 kU/L), early introduction group (EIG) infants developed significantly less food allergy to 1 or more foods than standard introduction group (SIG) infants (SIG, 34.2%; EIG, 19.2%; P = .03), and among infants with sensitization to egg at enrollment, EIG infants developed less egg allergy (SIG, 48.6%; EIG, 20.0%; P = .01). Similarly, among infants with moderate SCORAD (15-<40) at enrollment, EIG infants developed significantly less food allergy to 1 or more foods (SIG, 46.7%; EIG, 22.6%; P = .048) and less egg allergy (SIG, 43.3%; EIG, 16.1%; P = .02).

CONCLUSION

Early introduction was effective in preventing the development of food allergy in specific groups of infants at high risk of developing food allergy: those sensitized to egg or to any food at enrollment and those with eczema of increasing severity at enrollment. This efficacy occurred despite low adherence to the early introduction regimen. This has significant implications for the new national infant feeding recommendations that are emerging around the world.

Rational Design, Structure-Activity Relationship, and Immunogenicity of Hypoallergenic Pru p 3 Variants

SCOPE

Allergies to lipid transfer proteins involve severe adverse reactions; thus, effective and sustainable therapies are desired. Previous attempts disrupting disulfide bonds failed to maintain immunogenicity; thus, the aim is to design novel hypoallergenic Pru p 3 variants and evaluate the applicability for treatment of peach allergy.

METHODS AND RESULTS

Pru p 3 proline variant (PV) designed using in silico mutagenesis, cysteine variant (CV), and wild-type Pru p 3 (WT) are purified from Escherichia coli. Variants display homogenous and stable protein conformations with an altered secondary structure in circular dichroism. PV shows enhanced long-term storage capacities compared to CV similar to the highly stable WT. Using sera of 33 peach allergic patients, IgE-binding activity is reduced by 97% (PV) and 71% (CV) compared to WT. Both molecules show strong hypoallergenicity in Pru p 3 ImmunoCAP cross-inhibition and histamine release assays. Immunogenicity of PV is demonstrated with a phosphate-based adjuvant formulation in a mouse model.

CONCLUSIONS

An in silico approach is used to generate a PV without targeting disulfide bonds, T cell epitopes, or previously reported IgE epitopes of Pru p 3. PV is strongly hypoallergenic while structurally stable and immunogenic, thus representing a promising candidate for peach allergen immunotherapy.

Chemically modified peanut extract shows increased safety while maintaining immunogenicity

BACKGROUND

Peanuts are most responsible for food-induced anaphylaxis in adults in developed countries. An effective and safe immunotherapy is urgently needed. The aim of this study was to investigate the immunogenicity, allergenicity, and immunotherapeutic efficacy of a well-characterized chemically modified peanut extract (MPE) adsorbed to Al(OH)₃ .

METHODS

Peanut extract (PE) was modified by reduction and alkylation. Using sera of peanut-allergic patients, competitive IgE-binding assays and mediator release assays were performed. The immunogenicity of MPE was evaluated by measuring activation of human PE-specific T-cell lines and the induction of PE-specific IgG in mice. The safety and efficacy of MPE adsorbed to Al(OH)₃ was tested in two mouse models by measuring allergic manifestations upon peanut challenge in peanut-allergic mice.

RESULTS

Compared to PE, the IgE-binding and capacity to induce allergic symptoms of MPE were lower in all patients. PE and MPE displayed similar immunogenicity in vivo and in vitro. In mice sensitized to PE, the threshold for anaphylaxis (drop in BT) upon subcutaneous challenge with PE was 0.01 mg, while at 0.3 mg MPE no allergic reaction occurred. Anaphylaxis was not observed when PE and MPE were fully adsorbed to Al(OH)₃ . Both PE and MPE + Al(OH)₃ showed to be efficacious in a model for immunotherapy.

CONCLUSION

In our studies, an Al(OH)₃ adsorbed MPE showed reduced allergenicity compared to unmodified PE, while the efficacy of immunotherapy is maintained. The preclinical data presented in this study supports further development of modified peanut allergens for IT.

Localization of Four Allergens in Artemisia Pollen by Immunofluorescent Antibodies

BACKGROUND

Artemisia pollens have a high potential to induce allergic symptoms. Seven allergen components have been identified, but only Art v 7 has been localized in the pollen grain. This study aimed to localize the allergens in the pollen grains of 4 Artemisia spp.

METHODS

Pollen extracts from 2 Chinese Artemisia spp., A. argyi and A. annua, were used to immunize BALB/c mice. Recombinant Art v 1 and Art v 3 allergens were used to select specific monoclonal antibodies (mAbs). Three mAbs were used to purify the natural allergens and were then analyzed by mass spectrometry. As reported previously, polyclonal antibodies were obtained from rabbits immunized with 3 synthesized peptides of Art an 7. Using conventional histology procedures with pollens from 4 Artemisia spp. (A. argyi, A. annua, A. capilaris, and A. sieversiana), allergen images were observed and recorded by fluorescence and confocal laser microscopy.

RESULTS

We obtained 2 specific mAbs against Art v 1, 1 against Art v 2, and 4 against Art v 3 homologs. The Art v 1 and Art v 3 homologs were mainly located on the pollen walls, and the Art v 7 homologous protein was localized intracellularly around nuclei. The location of the Art v 2 homologous protein varied across species, being intracellular around nuclei for A. annua and A. argyi, and in both the pollen wall and around nuclei for A. capilaris and A. sieversiana.

CONCLUSIONS

Four mugwort allergens were localized in the pollen, and the major Art v 1 and Art v 3 allergens were located mainly in the pollen wall.

Artemisia pollen allergy in China: Component-resolved diagnosis reveals allergic asthma patients have significant multiple allergen sensitization

Background

Artemisia pollen allergy is a major cause of asthma in Northern China. Possible associations between IgE responses to Artemisia allergen components and clinical phenotypes have not yet been evaluated. This study was to establish sensitization patterns of four Artemisia allergens and possible associations with demographic characteristics and clinical phenotypes in three areas of China.

Methods

Two hundred and forty patients allergic to Artemisia pollen were examined, 178 from Shanxi and 30 from Shandong Provinces in Northern China, and 32 from Yunnan Province in Southwestern China. Allergic asthma, rhinitis, conjunctivitis, and eczema symptoms were diagnosed. All patients’ sera were tested by ImmunoCAP with mugwort pollen extract and the natural components nArt v 1, nArt ar 2, nArt v 3, and nArt an 7.

Results

The frequency of sensitization and the IgE levels of the four components in Artemisia allergic patients from Southwestern China were significantly lower than in those from the North. Art v 1 and Art an 7 were the most frequently recognized allergens (84% and 87%, respectively), followed by Art v 3 (66%) and Art ar 2 (48%). Patients from Northern China were more likely to have allergic asthma (50%) than patients from Southwestern China (3%), and being sensitized to more than two allergens increased the risk of allergic asthma, in which co‐sensitization to three major allergens Art v 1, Art v 3, and Art an 7 is prominent.

Conclusions

Component‐resolved diagnosis of Chinese Artemisia pollen‐allergic patients helps assess the potential risk of mugwort‐associated allergic asthma.

Do helminth infections underpin urban-rural differences in risk factors for allergy-related outcomes?

Background

It is proposed that helminth exposure protects against allergy‐related disease, by mechanisms that include disconnecting risk factors (such as atopy) from effector responses.

Objective

We aimed to assess how helminth exposure influences rural‐urban differences in risk factors for allergy‐related outcomes in tropical low‐ and middle‐income countries.

Methods

In cross‐sectional surveys in Ugandan rural Schistosoma mansoni (Sm)‐endemic islands, and in nearby mainland urban communities with lower helminth exposure, we assessed risk factors for atopy (allergen‐specific skin prick test [SPT] reactivity and IgE [asIgE] sensitization) and clinical allergy‐related outcomes (wheeze, urticaria, rhinitis and visible flexural dermatitis), and effect modification by Sm exposure.

Results

Dermatitis and SPT reactivity were more prevalent among urban participants, urticaria and asIgE sensitization among rural participants. Pairwise associations between clinical outcomes, and between atopy and clinical outcomes, were stronger in the urban survey. In the rural survey, SPT positivity was inversely associated with bathing in lakewater, Schistosoma‐specific IgG4 and Sm infection. In the urban survey, SPT positivity was positively associated with age, non‐Ugandan maternal tribe, being born in a city/town, BCG scar and light Sm infection. Setting (rural vs urban) was an effect modifier for risk factors including Sm‐ and Schistosoma‐specific IgG4. In both surveys, the dominant risk factors for asIgE sensitization were Schistosoma‐specific antibody levels and helminth infections. Handwashing and recent malaria treatment reduced odds of asIgE sensitization among rural but not urban participants. Risk factors for clinical outcomes also differed by setting. Despite suggestive trends, we did not find sufficient evidence to conclude that helminth (Sm) exposure explained rural‐urban differences in risk factors.

Conclusions and clinical relevance

Risk factors for allergy‐related outcomes differ between rural and urban communities in Uganda but helminth exposure is unlikely to be the sole mechanism of the observed effect modification between the two settings. Other environmental exposures may contribute significantly.

Ratios of specific IgG4 over IgE antibodies do not improve prediction of peanut allergy nor of its severity compared to specific IgE alone

Background

IgG₄ antibodies have been suggested to play a protective role in the translation of peanut sensitization into peanut allergy. Whether they have added value as diagnostic read‐out has not yet been reported.

Objective

To evaluate whether (a) peanut‐specific IgG, IgG₄ and/or IgA antibodies are associated with tolerance and/or less severe reactions and (b) they can improve IgE‐based diagnostic tests.

Methods

Sera of 137 patients with challenge‐proven peanut allergy and of 25 subjects that tolerated peanut, both with known IgE profiles to peanut extract and five individual peanut allergens, were analyzed for specific IgG and IgG₄. Antibody levels and ratios thereof were associated with challenge outcome including symptom severity grades. For comparison of the discriminative performance, receiver operating characteristic curve (ROC) analysis was used.

Results

IgE against Ara h 2 was significantly higher in allergic than in tolerant patients and associated with severity of reactions (P < 0.001) with substantial diagnostic capability (AUC 0.91, 95%CI 0.87‐0.96 and 0.80, 95%CI 0.73‐0.87, respectively). IgG and IgG₄ were also positively associated albeit significantly weaker (AUCs from 0.65 to 0.72). On the other hand, ratios of IgG and IgG₄ over IgE were greater in patients that were tolerant or had mild symptoms as compared to severe patients but they did not predict challenge outcomes better than IgE alone (AUCs from 0.54 to 0.89).

Conclusion

IgE against Ara h 2 is the best biomarker for predicting peanut challenge outcomes including severity and IgG and IgG₄ antibody ratios over IgE do not improve these outcomes.

Abnormal Responses to Local Esophageal Food Allergen Injections in Adult Patients With Eosinophilic Esophagitis

Skin tests and measurement of serum levels of immunoglobulin E do not accurately identify foods for elimination from the diets of patients with eosinophilic esophagitis (EoE). We investigated whether an esophageal prick test, in which the esophageal mucosa is challenged by local injection of allergen extracts, could identify individuals with esophageal sensitization. During endoscopy, 6 allergens were injected in the esophagus of 8 patients with EoE and 3 patients without EoE (controls). A second endoscopy was performed after 24 hours to evaluate delayed responses. Five of the 8 patients with EoE had evidence for an acute response (luminal obstruction and mucosal blanching); 2 other patients had a delayed wheal or flare reaction. No responses were observed in controls. We conclude that esophageal mucosal food allergen injections induce acute and/or delayed responses in patients with EoE but not controls. The esophageal prick test deserves further exploration because it may guide elimination diets.

IgE-binding potencies of three peach Pru p 1 isoforms

SCOPE

Pru p 1, the Bet v 1 homologue from peach, has been identified as a clinically relevant allergen. Three isoforms have been described, two in peach fruit (Pru p 1.0101 and Pru p 1.0201) and one in pollen (Pru p 1.0301). The present study aimed to compare their IgE-binding potencies.

METHODS AND RESULTS

Three Pru p 1 isoforms were cloned and expressed as soluble proteins with His-tags in Escherichia coli. Protein identity was confirmed by MS, circular dichroism, and RNAse activity. IgE-binding capacity using ELISA and ImmunoCAP was compared. Three Pru p 1 isoforms had quite similar IgE-binding potencies for 60% of the sera, but more than twofold between any two isoforms among 40% of the 47 sera. The mean IgE binding of Pru p 1.0201 was slightly higher than other two isoforms. In a sera pool, homologous ImmunoCAP inhibition was higher than other two heterologous isoforms. Individual serum with diverse IgE values of three isoforms demonstrated the higher IgE inhibition of specific isoform with higher IgE value.

CONCLUSION

A similar and variable pattern of IgE recognition was observed among three Pru p 1 isoforms. The two new isoforms can be used as more accurate diagnostic reagents.

Changes in IgE sensitization and total IgE levels over 20 years of follow-up

Background

Cross-sectional studies have reported a lower prevalence of sensitization in older adults, but few longitudinal studies have examined whether this is an aging or a year-of-birth cohort effect.

Objective

We sought to assess changes in sensitization and total IgE levels in a cohort of European adults as they aged over a 20-year period.

Methods

Levels of serum specific IgE to common aeroallergens (house dust mite, cat, and grass) and total IgE levels were measured in 3206 adults from 25 centers in the European Community Respiratory Health Survey on 3 occasions over 20 years. Changes in sensitization and total IgE levels were analyzed by using regression analysis corrected for potential differences in laboratory equipment and by using inverse sampling probability weights to account for nonresponse.

Results

Over the 20-year follow-up, the prevalence of sensitization to at least 1 of the 3 allergens decreased from 29.4% to 24.8% (−4.6%; 95% CI, −7.0% to −2.1%). The prevalence of sensitization to house dust mite (−4.3%; 95% CI, −6.0% to −2.6%) and cat (−2.1%; 95% CI, −3.6% to −0.7%) decreased more than sensitization to grass (−0.6%; 95% CI, −2.5% to 1.3%). Age-specific prevalence of sensitization to house dust mite and cat did not differ between year-of-birth cohorts, but sensitization to grass was most prevalent in the most recent ones. Overall, total IgE levels decreased significantly (geometric mean ratio, 0.63; 95% CI, 0.58-0.68) at all ages in all year-of-birth cohorts.

Conclusion

Aging was associated with lower levels of sensitization, especially to house dust mite and cat, after the age of 20 years.

Hazelnut allergy across Europe dissected molecularly: A EuroPrevall outpatient clinic survey

BACKGROUND

Hazelnut allergy is birch pollen-driven in Northern/Western Europe and lipid transfer protein-driven in Spain and Italy. Little is known about other regions and other allergens.

OBJECTIVE

Establishing a molecular map of hazelnut allergy across Europe.

METHODS

In 12 European cities, subjects reporting reactions to hazelnut (n = 731) were evaluated and sensitization to 24 foods, 12 respiratory allergen sources, and latex was tested by using skin prick test and ImmunoCAP. A subset (124 of 731) underwent a double-blind placebo-controlled food challenge to hazelnut. Sera of 423 of 731 subjects were analyzed for IgE against 7 hazelnut allergens and cross-reactive carbohydrate determinants by ImmunoCAP.

RESULTS

Hazelnut allergy was confirmed in 70% of those undergoing double-blind placebo-controlled food challenges. Birch pollen-driven hazelnut sensitization (Cor a 1) dominated in most cities, except in Reykjavik, Sofia, Athens, and Madrid, where reporting of hazelnut allergy was less frequent anyhow. In Athens, IgE against Cor a 8 dominated and strongly correlated with IgE against walnut, peach, and apple and against Chenopodium, plane tree, and mugwort pollen. Sensitization to seed storage proteins was observed in less than 10%, mainly in children, and correlated with IgE to nuts, seeds, and legumes. IgE to Cor a 12, observed in all cities (10% to 25%), correlated with IgE to nuts, seeds, and pollen.

CONCLUSIONS

In adulthood, the importance of hazelnut sensitization to storage proteins, oleosin (Cor a 12), and Cor a 8 is diluted by the increased role of birch pollen cross-reactivity with Cor a 1. Cor a 8 sensitization in the Mediterranean is probably driven by diet in combination with pollen exposure. Hazelnut oleosin sensitization is prevalent across Europe; however, the clinical relevance remains to be established.

Development of a hypoallergenic recombinant parvalbumin for first-in-man subcutaneous immunotherapy of fish allergy

BACKGROUND

The FAST (food allergy-specific immunotherapy) project aims at developing safe and effective subcutaneous immunotherapy for fish allergy, using recombinant hypoallergenic carp parvalbumin, Cyp c 1.

OBJECTIVES

Preclinical characterization and good manufacturing practice (GMP) production of mutant Cyp (mCyp) c 1.

METHODS

Escherichia coli-produced mCyp c 1 was purified using standard chromatographic techniques. Physicochemical properties were investigated by gel electrophoresis, size exclusion chromatography, circular dichroism spectroscopy, reverse-phase high-performance liquid chromatography and mass spectrometry. Allergenicity was assessed by ImmunoCAP inhibition and basophil histamine release assay, immunogenicity by immunization of laboratory animals and stimulation of patients' peripheral blood mononuclear cells (PBMCs). Reference molecules were purified wild-type Cyp c 1 (natural and/or recombinant). GMP-compliant alum-adsorbed mCyp c 1 was tested for acute toxicity in mice and rabbits and for repeated-dose toxicity in mice. Accelerated and real-time protocols were used to evaluate stability of mCyp c 1 as drug substance and drug product.

RESULTS

Purified mCyp c 1 behaves as a folded and stable molecule. Using sera of 26 double-blind placebo-controlled food-challenge-proven fish-allergic patients, reduction in allergenic activity ranged from 10- to 5,000-fold (1,000-fold on average), but with retained immunogenicity (immunization in mice/rabbits) and potency to stimulate human PBMCs. Toxicity studies revealed no toxic effects and real-time stability studies on the Al(OH)3-adsorbed drug product demonstrated at least 20 months of stability.

CONCLUSION

The GMP drug product developed for treatment of fish allergy has the characteristics targeted for in FAST: i.e. hypoallergenicity with retained immunogenicity. These results have warranted first-in-man immunotherapy studies to evaluate the safety of this innovative vaccine.

The association between foodborne and orofecal pathogens and allergic sensitisation -- EuroPrevall study

BACKGROUND

An inverse association between markers of exposure to foodborne and orofecal pathogens and allergic sensitization has been reported. However, the findings of epidemiological studies have not been consistent. This study investigated the relationship between antibodies to hepatitis A, Toxoplasma gondii and salmonella and allergic sensitization to food and aeroallergens in children from different geographical areas.

METHODS

Specific IgE and/or skin prick testing against food and aeroallergens were measured in children from 6 to 12 years of age residing in Greece, the Netherlands, China, India and Russia. Seropositivity to the three pathogens was measured, and data on potential confounders were collected using questionnaire.

RESULTS

Data from 800 children (126 from Athens; 248 from Utrecht; 110 from Hong Kong; 119 from urban Tomsk; and 197 from rural Tomsk) could be analysed. The highest percentage of positive serology to salmonella was found in Hong Kong (46.4%), to T. gondii in urban Tomsk (13.4%) and to hepatitis A in Athens (71.2%). Although not significant, T. gondii seropositivity tends to be negatively associated, and hepatitis A seropositivity tends to be positively associated with allergic sensitization.

CONCLUSION

Inconsistent associations were observed between allergic sensitization to food and aeroallergens and markers of exposure to two common foodborne pathogens. The association with T. gondii tends to be negative, consistent with the 'hygiene hypothesis', but the association with hepatitis A tends to be positive. Taken together, there is no clear evidence that past exposure to foodborne and orofecal pathogens protects against allergic sensitization to food or aeroallergens.

Ara h 6 complements Ara h 2 as an important marker for IgE reactivity to peanut

The similarities of two major peanut allergens, Ara h 2 and Ara h 6, in molecular size, amino acid sequence, and structure have made it difficult to obtain natural Ara h 6 free of Ara h 2. The objectives of this study were to purify natural Ara h 6 that is essentially free of Ara h 2 and to compare its IgE reactivity and potency in histamine release assays to Ara h 2. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the highly purified allergen (<0.01% Ara h 2) revealed a single 14.5 kD band, and the identity of Ara h 6 was confirmed by liquid chromatography-tandem mass spectrometry. Ara h 6 showed a higher seroprevalence in chimeric IgE enzyme-linked immunosorbent assay (n = 54) but a weaker biological activity in basophil histamine release assays than Ara h 2. Purified Ara h 6 will be useful for diagnostic IgE antibody assays as well as molecular and cellular studies to investigate the immunological mechanisms of peanut allergy.

Risk Factors Associated with the Development of Atopic Sensitization in Indonesia

Background

The prevalence of allergic diseases has increased not only in high income but also in low-to-middle income countries. However, risk factors for their development are still not well established, particularly in the latter.

Objective

To assess prevalence and identify risk factors for sensitization to two major inhalant allergens among children from semi-urban and rural areas in Indonesia.

Method

A cross-sectional survey was performed among 1,674 school children aged 5–15 years old. Information on potential risk factors and reported allergic symptoms were obtained by questionnaire. Helminth infections were assessed. Skin prick tests (SPT) were performed, total IgE as well as allergen-specific IgE for house dust mite (HDM) and cockroach were measured.

Result

The prevalence of allergic skin sensitization to both aeroallergens was significantly higher in the semi-urban than in the rural area. However, serum IgE against HDM and cockroach as well as total IgE were significantly lower in semi-urban than in rural children. In the semi-urban area, there was a significant positive association between SPT to HDM and higher paternal education but a negative one with hookworm infection. The risk factors linked to cockroach sensitization were different: being of a farmer offspring and lacking access to piped water were associated with an increased risk for a positive SPT to cockroach. No significant associations between measured risk factors and having a positive SPT were found in the rural area.

Conclusion

Sensitization to HDM and cockroach is common in Indonesia, more often translating into a positive SPT in the semi-urban than in the rural setting. Whereas high paternal education and low hookworm infection were associated with increased risk of SPT to HDM, we were surprised to find parameters of lower SES were identified as risk factor for cockroach SPT.

Peanut-specific IgE antibodies in asymptomatic Ghanaian children possibly caused by carbohydrate determinant cross-reactivity

Background

The prevalence of peanut allergy has increased in developed countries, but little is known about developing countries with high peanut consumption and widespread parasitic infections.

Objective

We sought to investigate peanut allergy in Ghana.

Methods

In a cross-sectional survey among Ghanaian schoolchildren (n = 1604), data were collected on reported adverse reactions to peanut, peanut sensitization (serum specific IgE and skin reactivity), consumption patterns, and parasitic infections. In a subset (n = 43) IgE against Ara h 1, 2, 3, and 9 as well as cross-reactive carbohydrate determinants (CCDs) was measured by using ImmunoCAP. Cross-reactivity and biological activity were investigated by means of ImmunoCAP inhibition and basophil histamine release, respectively.

Results

Adverse reactions to peanut were reported in 1.5%, skin prick test reactivity in 2.0%, and IgE sensitization (≥0.35 kU/L) in 17.5% of participants. Moreover, 92.4% of those IgE sensitized to peanut (≥0.35 kU/L) had negative peanut skin prick test responses. Schistosoma haematobium infection was positively associated with IgE sensitization (adjusted odds ratio, 2.29; 95% CI, 1.37-3.86). In the subset IgE titers to Ara h 1, 2, 3, and 9 were low (<1.3 kU/L), except for 6 moderately strong reactions to Ara h 9. IgE against peanut was strongly correlated with IgE against CCDs (r = 0.89, P < .0001) and could be almost completely inhibited by CCDs, as well as S haematobium soluble egg antigen. Moreover, IgE to peanut showed poor biological activity.

Conclusions

Parasite-induced IgE against CCDs might account largely for high IgE levels to peanut in our study population of Ghanaian schoolchildren. No evidence of IgE-mediated peanut allergy was found.

The development of TH2 responses from infancy to 4 years of age and atopic sensitization in areas endemic for helminth infections

Background

Helminth infections and allergies are associated with TH₂ responses. Whereas the development of TH₂ responses and allergic disorders in pediatric populations has been examined in affluent countries, no or little data exist from low income regions of the world.

The aim of this study is to examine factors influencing the development of TH₂ responses of children born in areas endemic for helminth infections and to relate these factors to atopic sensitization at 4 years of age.

Methods

Data were collected from pregnant mothers on helminth infections, education and socioeconomic status (SES). Total IgE, IL-5 in response to mitogen, and helminth antigens were measured in children at 2, 5, 12, 24 and 48 months of age. Skin prick testing (SPT) and allergen-specific IgE were determined at 4 years of age.

Results

Strong TH₂ responses were seen at 5 months of age and increased with time. Although maternal filarial infection was associated with helminth-antigen specific TH₂ responses, it was low maternal education or SES but not helminth infection, which was associated with the development of high total IgE and PHA-induced IL-5. At 4 years of age when allergen reactivity was assessed by SPT, the high general TH₂ responses did not translate into higher prevalence of SPT. The risk factor for SPT reactivity was low maternal education which decreased the risk of SPT positivity to allergens (adjusted OR, 0.32; 95% CI, 0.12 – 0.87) independently of maternal filarial infection which tended to reduce the child’s risk for being SPT positive (adjusted OR, 0.35; 95% CI, 0.07 – 1.70).

Conclusions

In areas endemic for helminths, potent TH₂ responses were seen early in life, but did not translate into a higher SPT reactivity to allergens. Therefore, in many parts of the world TH₂ responses in general and IgE in particular cannot be used for diagnosis of allergic diseases.

FAST: towards safe and effective subcutaneous immunotherapy of persistent life-threatening food allergies

The FAST project (Food Allergy Specific Immunotherapy) aims at the development of safe and effective treatment of food allergies, targeting prevalent, persistent and severe allergy to fish and peach. Classical allergen-specific immunotherapy (SIT), using subcutaneous injections with aqueous food extracts may be effective but has proven to be accompanied by too many anaphylactic side-effects. FAST aims to develop a safe alternative by replacing food extracts with hypoallergenic recombinant major allergens as the active ingredients of SIT. Both severe fish and peach allergy are caused by a single major allergen, parvalbumin (Cyp c 1) and lipid transfer protein (Pru p 3), respectively. Two approaches are being evaluated for achieving hypoallergenicity, i.e. site-directed mutagenesis and chemical modification. The most promising hypoallergens will be produced under GMP conditions. After pre-clinical testing (toxicology testing and efficacy in mouse models), SCIT with alum-absorbed hypoallergens will be evaluated in phase I/II^a and II^b randomized double-blind placebo-controlled (DBPC) clinical trials, with the DBPC food challenge as primary read-out. To understand the underlying immune mechanisms in depth serological and cellular immune analyses will be performed, allowing identification of novel biomarkers for monitoring treatment efficacy. FAST aims at improving the quality of life of food allergic patients by providing a safe and effective treatment that will significantly lower their threshold for fish or peach intake, thereby decreasing their anxiety and dependence on rescue medication.

Diminished response to grass pollen allergen challenge in subjects with concurrent house dust mite allergy

INTRODUCTION

The clinical manifestation of allergic rhinitis is influenced by many factors; while different subpopulations are not well defined. Different combinations of allergic sensitization may lead to different clinical manifestations of allergic disease.

METHODS

In a nasal allergen challenge model we compared allergic rhinitis symptoms between subjects mono-sensitized to grass pollen or house dust mite, poly-sensitized subjects, and healthy controls. We measured visual analogue scales of symptoms and peak nasal inspiratory flow. We also compared serum total IgE, allergen-specific IgE and IgG4, and basophil histamine release.

RESULTS

Nasal challenge with grass pollen extract led to a significantly larger increase in subjective (p = 0.031) and objective (p = 0.001) nasal symptoms in grass pollen mono-sensitized subjects than in poly-sensitized subjects. No differences were found in serum levels of allergen-specific IgE and IgG4 or in biological activity of IgE (basophil histamine release) between mono-sensitized and poly-sensitized subjects. We found a strong inverse correlation between serum allergen-specific IgE and basophil histamine release (-0.789, p = 0.001).

CONCLUSIONS

Grass pollen mono-sensitized subjects have a more severe clinical response to nasal challenge than poly-sensitized subjects. This cannot be explained by serum levels of IgE or its biological activity. The continuous allergen exposure in poly-sensitized subjects may alter local immuno-regulatory processes, leading to a reduced clinical response to allergen challenge.

The canine sarcoglycan delta gene: BAC clone contig assembly, chromosome assignment and interrogation as a candidate gene for dilated cardiomyopathy in Dobermann dogs

Dilated cardiomyopathy (DCM) is a common disease of the myocardium recognized in human, dog and experimental animals. Genetic factors are responsible for a large proportion of cases in humans, and 17 genes with DCM causing mutations have been identified. The genetic origin of DCM in the Dobermann dogs has been suggested, but no disease genes have been identified to date. In this paper, we describe the characterization and evaluation of the canine sarcoglycan delta (SGCD), a gene implicated in DCM in human and hamster. Bacterial artificial chromosomes (BACs) containing the canine SGCD gene were isolated with probes for exon 3 and exons 4-8 and were characterized by Southern blot analysis. BAC end sequences were obtained for four BACs. Three of the BACs overlapped and could be ordered relative to each other and the end sequences of all four BACs could be anchored on the preliminary assembly of the dog genome sequence (www. ensembl.org). One of the BACs of the partial contig was localized by fluorescent in situ hybridization to canine chromosome 4q22, in agreement with the dog genome sequence. Two highly informative polymorphic microsatellite markers in intron 7 of the SGCD gene were identified. In 25 DCM-affected and 13 non DCM-affected dogs seven different haplotypes could be distinguished. However, no association between any of the SGCD variants and the disease locus was apparent.

Characterization of the canine desmin (DES) gene and evaluation as a candidate gene for dilated cardiomyopathy in the Dobermann

Canine-dilated cardiomyopathy (DCM) in dogs is a disease of the myocardium associated with dilatation and impaired contraction of the ventricles and is suspected to have a genetic cause. A missense mutation in the desmin gene (DES) causes DCM in a human family. Human DCM closely resembles the canine disease. In the present study, we evaluated whether DES gene mutations are responsible for DCM in Dobermann dogs. We have isolated bacterial artificial chromosome clones (BACs) containing the canine DES gene and determined the chromosomal location by fluorescence in situ hybridization (FISH). Using data deposited in the NCBI trace archive and GenBank, the canine DES gene DNA sequence was assembled and seven single nucleotide polymorphisms (SNPs) were identified. From the canine DES gene BAC clones, a polymorphic microsatellite marker was isolated. The microsatellite marker and four informative desmin SNPs were typed in a Dobermann family with frequent DCM occurrence, but the disease phenotype did not associate with a desmin haplotype. We concluded that mutations in the DES gene do not play a role in Dobermann DCM. Availability of the microsatellite marker, SNPs and DNA sequence reported in this study enable fast evaluation of the DES gene as a DCM candidate gene in other dog breeds with DCM occurrence.

DNA testing for type III von Willebrand disease in Dutch Kooiker dogs

Von Willebrand disease type III is widespread in Dutch Kooiker dogs. To eradicate von Willebrand disease from the breed, affected dogs and nonsymptomatic carriers must be excluded from breeding. Previous efforts to detect carriers in Kooiker dogs by a von Willebrand factor antigen assay were not satisfactory because of considerable overlap of plasma concentrations in normal dogs and carriers. The aim of this study was to develop and apply a DNA test for the detection of von Willebrand disease carriers in the Kooiker breed. Two mutations in the von Willebrand factor gene in affected Kooiker dogs have been described previously, a splice site mutation at the border of intron 16 and exon 16 and a missense mutation in exon 3. We have developed polymerase chain reaction tests for both mutations in genomic DNA. The missense mutation most likely is a neutral variant and appears to be a polymorphism present in many breeds. The allele-specific oligonucleotide test for the splice site mutation was applied in the selection of animals cleared to breed by the Dutch breeding club. In a few years, the mutation has been eliminated from the breeding stock without apparent increase of inbreeding or preferential sire usage.

Isolation and characterization of the canine serotonin receptor 1B gene (htr1B)

The serotonin receptor 1B gene (htr1B) has been suggested to be implicated in mental disorders in both humans and other species. We have isolated a canine bacterial artificial chromosome (BAC) clone containing htr1B, revealed the coding and surrounding DNA sequence of canine htr1B and designed primer sets for genomic sequencing of the gene. A mutation scan in 10 dogs revealed five single nucleotide polymorphisms in the htr1B coding sequence. By random sequencing of subclones of the BAC a polymorphic microsatellite repeat was found. We found evidence for at least four extended haplotypes in six dogs of the same breed. The chromosomal localization of the gene was confirmed by fluorescence in situ hybridisation and radiation hybrid mapping. This work provides a starting point for mutation scans and association studies on dogs with behavioural problems.

Familial footpad hyperkeratosis and inheritance of keratin 2, keratin 9, and desmoglein 1 in two pedigrees of Irish Terriers

OBJECTIVE

To investigate the possibility that variants in the acidic or basic keratin genes or in desmoglein 1 may cause the clinical manifestation of familial footpad hyperkeratosis in Irish Terriers.

ANIMALS

11 dogs belonging to 2 related affected pedigrees of Irish Terriers.

PROCEDURE

Genomic DNA was extracted from blood samples obtained from each dog. The DNA markers linked to the genes keratin 2, keratin 9, and desmoglein 1 were amplified by use of a polymerase chain reaction technique, and length of the products was determined by use of an automatic DNA analyzer.

RESULTS

All tested markers yielded information. None of the markers (genotype) cosegregated with the clinical status of the dogs (phenotype) in the 2 pedigrees.

CONCLUSIONS AND CLINICAL RELEVANCE

Mutations in the genes encoding keratin 2 and 9 as well as desmoglein 1 are highly unlikely to be the primary cause of familial footpad hyperkeratosis in Irish Terriers.