Genome-wide association study reveals an association between the HLA-DPB1∗02:01:02 allele and wheat-dependent exercise-induced anaphylaxis.

Wheat-dependent exercise-induced anaphylaxis (WDEIA) is a life-threatening food allergy triggered by wheat in combination with the second factor such as exercise. The identification of potential genetic risk factors for this allergy might help high-risk individuals before consuming wheat-containing food. We aimed to identify genetic variants associated with WDEIA. A genome-wide association study was conducted in a discovery set of 77 individuals with WDEIA and 924 control subjects via three genetic models. The associations were confirmed in a replication set of 91 affected individuals and 435 control individuals. Summary statistics from the combined set were analyzed by meta-analysis with a random-effect model. In the discovery set, a locus on chromosome 6, rs9277630, was associated with WDEIA in the dominant model (OR = 3.95 [95% CI, 2.31-6.73], p = 7.87 × 10-8). The HLA-DPB1∗02:01:02 allele displayed the most significant association with WDEIA (OR = 4.51 [95% CI, 2.66-7.63], p = 2.28 × 10-9), as determined via HLA imputation following targeted sequencing. The association of the allele with WDEIA was confirmed in replication samples (OR = 3.82 [95% CI, 2.33-6.26], p = 3.03 × 10-8). A meta-analysis performed in the combined set revealed that the HLA-DPB1∗02:01:02 allele was significantly associated with an increased risk of WDEIA (OR = 4.13 [95% CI, 2.89-5.93], p = 1.06 × 10-14). Individuals carrying the HLA-DPB1∗02:01:02 allele have a significantly increased risk of WDEIA. Further validation of these findings in independent multiethnic cohorts is needed.

Efficacy and safety of omalizumab in adult patients with wheat-dependent exercise-induced anaphylaxis: Reduction of in vitro basophil activation and allergic reaction to wheat.

BACKGROUND: In patients with wheat-dependent exercise-induced anaphylaxis (WDEIA), anaphylactic shock occurs frequently, therefore avoidance of wheat products is recommended. We aimed to evaluate efficacy and safety of long-term omalizumab treatment for adult patients with WDEIA. METHODS: In this phase 2, multicentre single-arm trial, 20 adult patients with WDEIA were enrolled (UMIN 000019250). All patients were administered 150-600 mg of omalizumab subcutaneously and evaluations (basophil activation and blood examination) were performed at regular intervals during administration period (0-48 weeks) and observation period (48-68 weeks). Primary endpoint was proportion of the patients who achieved a basophil activation rate below 10% with fractionated wheat preparations, and secondary endpoint was proportion of the patients with no allergic reactions after wheat products ingestion. RESULTS: During the omalizumab treatment, more than 80% of the patients achieved the basophil activation rate less than 10% against all fractionated wheat preparations, and 68.8% of the patients who achieved the primary endpoint experienced no allergic reaction. During the observation period, the proportion of the patients who achieved a basophil activation rate below 10% decreased gradually, and the proportion of patients with positive allergic reactions increased gradually thereafter and reached maximum of 46.7%. Severe adverse events were not observed during the study. CONCLUSIONS: Long-term omalizumab treatment is safe and effective for adult patients with WDEIA when assessed by basophil activation rate with wheat allergens as well as allergic reactions after lifting of restrictions on wheat intake. However, this is not enough to achieve desensitization.

A novel detection method for cross-linking of IgE-receptors by autoantibodies in chronic spontaneous urticaria.

BACKGROUND: Autoantibodies (AAbs) against immunoglobulin E (IgE) antibodies (Abs) and their high-affinity receptor alpha subunits (FcεRIα) are key factors in the elicitation of type IIb autoimmune chronic spontaneous urticaria (type IIb aiCSU). In this study, we aimed to develop a new method to detect functional anti-FcεRIα and anti-IgE AAbs, which can crosslink the plural FcεRІα molecules and IgE Abs on the surface of mast cells and basophils, in sera from aiCSU patients using the amplified luminescence proximity homogeneous assay (Alpha). METHODS: Sera were obtained from 14 aiCSU patients, as diagnosed by recurrent chronic spontaneous urticaria episodes and positive results for the autologous serum skin test and/or histamine release test (HRT). The AAbs to FcεRIα and IgE Abs were determined in sera from aiCSU patients using enzyme-linked immunosorbent assay (ELISA) and Alpha by cross-linking (AlphaCL) of IgE Abs and/or FcεRІα. RESULTS: Serum anti-FcεRIα and anti-IgE AAb levels were not significantly different between aiCSU patients and healthy subjects in ELISA. Anti-FcεRIα AAbs were detected in 10 of 14 aiCSU patients who displayed positive (5/5) and negative (5/9) results in the HRT for anti-FcεRIα AAbs by AlphaCL, whereas no signals were observed in healthy subjects. Additionally, anti-IgE AAbs were detected in two of four aiCSU patients who displayed positive results in the HRT for anti-IgE AAbs. CONCLUSIONS: A new assay method using AlphaCL can detect anti-FcεRIα and anti-IgE AAbs with FcεRIα- and IgE-crosslinking abilities in sera from aiCSU patients. This simple and practical assay method may be available as a diagnostic tool for urticaria patients.

Identification of peroxidase-1 and beta-glucosidase as cross-reactive wheat allergens in grass pollen-related wheat allergy.

BACKGROUND: Some patients with wheat-dependent exercise-induced anaphylaxis (WDEIA) or wheat allergy showed negative ω-5 gliadin-specific IgE test and high level of grass pollen-specific IgE. It was presumed that these patients developed allergic reaction upon cross-reaction of their IgE antibodies raised against grass pollen allergens to wheat allergens. This study aimed to clarify clinical characteristics and wheat allergens of this phenotype of WDEIA/wheat allergy, which were tentatively diagnosed as grass pollen-related wheat allergy (GPWA). METHODS: A total of six patients with GPWA were enrolled, and controls were 17 patients with grass pollen allergy but no episode of wheat allergy, and 29 patients with other wheat allergies: 18 with conventional WDEIA and 11 with hydrolyzed wheat protein allergy. Sensitization to wheat proteins was determined by basophil activation test (BAT). IgE-binding proteins in wheat flour were identified by immunoblotting followed by mass spectrometry. Wheat allergen-specific IgE tests were established by CAP-FEIA system. RESULTS: All the six patients with GPWA were sensitized to water-soluble wheat proteins in BAT and IgE-immunoblotting, and peroxidase-1 (35 kDa) and beta-glucosidase (60 kDa) were identified as specific IgE-binding wheat proteins. The binding of patient IgE to these proteins was inhibited by pre-incubation of patient sera with grass pollen. The peroxidase-1- and beta-glucosidase-specific IgE tests identified three and four of six patients with GPWA, respectively, but only two of 29 controls, indicating high specificity of these tests. CONCLUSIONS: Peroxidase-1 and beta-glucosidase are specific wheat allergens for GPWA among grass pollen allergy and other types of wheat-induced food allergies.

A Case of Pork-cat Syndrome That Developed as Food-dependent Exercise-induced Anaphylaxis.

is missing (Short communication).

HLA-DQ and RBFOX1 as susceptibility genes for an outbreak of hydrolyzed wheat allergy.

BACKGROUND: Food allergy is a growing health problem worldwide because of its increasing prevalence, life-threatening potential, and shortage of effective preventive treatments. In an outbreak of wheat allergy in Japan, thousands of patients had allergic reactions to wheat after using soap containing hydrolyzed wheat protein (HWP). OBJECTIVES: The aim of the present study was to investigate genetic variation that can contribute to susceptibility to HWP allergy. METHODS: We conducted a genome-wide association study of HWP allergy in 452 cases and 2700 control subjects using 6.6 million genotyped or imputed single nucleotide polymorphisms. Replication was assessed by genotyping single nucleotide polymorphisms in independent samples comprising 45 patients with HWP allergy and 326 control subjects. RESULTS: Through the genome-wide association study, we identified significant associations with the class II HLA region on 6p21 (P = 2.16 × 10-24 for rs9271588 and P = 2.96 × 10-24 for HLA-DQα1 amino acid position 34) and with the RBFOX1 locus at 16p13 (rs74575857, P = 8.4 × 10-9). The associations were also confirmed in the replication data set. Both amino acid polymorphisms (HLA-DQß1 amino acid positions 13 and 26) located in the P4 binding pockets on the HLA-DQ molecule achieved the genome-wide significance level (P < 5.0 × 10-8). CONCLUSIONS: Our data provide the first demonstration of genetic risk for HWP allergy and show that this genetic risk is mainly represented by multiple combinations of HLA variants.

Type-I-hypersensitivity to 15 kDa, 28 kDa and 54 kDa proteins in vitellogenin specific to Gadus chalcogrammus roe.

BACKGROUND: Fish roe allergy is a common health problem in countries where sea food is a major part of the diet, such as Japan. ß'-component (ß'-c) in fish roe has been identified as a major antigen for patients who show hypersensitivity to various fish roes. However, little is known about causative antigens for patients reactive to fish roe of specific species. METHODS: Serum and basophils were obtained from patients who had reactivity to roes of Gadus chalcogrammus (GC) and/or other fish species. GC roe specific antigens were analyzed by immunoblotting, histamine release assay (HRA) and mass spectrometry. Recombinant-fragments of vitellogenin (Vg) were obtained by the Escherichia coli expression system. RESULTS: Serum IgE of a patient with specific reactions to GC roe bound to 15, 28, 40 and 70 kDa-proteins in GC roe extract. Mass spectrometry analysis revealed that proteins in these bands contained fragments corresponding to Vg. Immunoblotting of Vg immunoprecipitated by rabbit anti-Vg antiserum from the extract revealed 15, 28 and 54 kDa fragments bound by the patient's IgE. These bindings were inhibited by the pretreatment of recombinant phosvitin (rPv) and ß'-c (rß'-c). Fractions obtained by native gel electrophoresis containing 15, 28 and 54 kDa proteins, but not the other fractions, induced significant histamine release from the patient's basophils. Sera of the other patients with GC roe specific-IgE showed IgE binding to rPv and/or rß'-c. CONCLUSIONS: The 15, 28 and 54 kDa-fragments of Vg which include structures of Pv and ß'-c, could be antigens for GC roe specific type-I-hypersensitivity.

Alpha-Gal-containing biologics and anaphylaxis.

Cetuximab, the IgG1 subclass chimeric mouse-human monoclonal antibody biologic that targets the epidermal growth factor receptor (EGFR), is used worldwide for the treatment of EGFR-positive unresectable progressive/recurrent colorectal cancer and head and neck cancer. Research has shown that the principal cause of cetuximab-induced anaphylaxis is anti-oligosaccharide IgE antibodies specific for galactose-α-1,3-galactose (α-Gal) oligosaccharide present on the mouse-derived Fab portion of the cetuximab heavy chain. Furthermore, it has been revealed that patients who are allergic to cetuximab also develop an allergic reaction to mammalian meat containing the same α-Gal oligosaccharide owing to cross-reactivity, and the presumed cause of sensitization is tick bites: Amblyomma in the United States, Ixodes in Australia and Europe, and Haemaphysalis in Japan. The α-Gal-specific IgE test (bovine thyroglobulin-conjugated ImmunoCAP) or CD63-expression-based basophil activation test may be useful to identify patients with IgE to α-Gal in order to predict risk for cetuximab-induced anaphylactic shock. Investigations of cetuximab-related anaphylaxis have revealed three novel findings that improve our understanding of immediate-type allergy: 1) oligosaccharide can serve as the main IgE epitope of anaphylaxis; 2) because of the oligosaccharide epitope, a wide range of cross-reactivity with mammalian meats containing α-Gal similar to cetuximab occurs; and 3) tick bites are a crucial factor of sensitization to the oligosaccharide. Nonetheless, taking a medical history of tick bites and beef allergy may be insufficient to prevent cetuximab-induced anaphylaxis, and therefore blood testing with an α-Gal-specific IgE test, with high sensitivity and specificity, is necessary to detect sensitization to α-Gal.

[EARLY CHILDHOOD-ONSET PORK-CAT SYNDROME DUE TO SENSITIZATION BY BOTH CATS AND DOGS -A CASE REPORT].

We present a case of early childhood-onset pork-cat syndrome possibly due to sensitization by both cats and dogs. A 6-year-old girl was referred to our hospital because of repetitive episodes of urticaria when she consumed pork meat. The patient lived with a dog and the ground floor of her house was a veterinary clinic run by her veterinarian parents. Blood tests demonstrated high specific IgE (≥50UA/ml) against cat dander, dog dander, pork, Sus s 1, Fel d 2, Can f 1, Can f 2, and Can f 3. The skin prick test was positive for raw pork and beef. Western blotting analysis detected hot spots on 67-kDa proteins in pork meat and cat dander extract. Cross-reactivity between these two proteins was confirmed by an inhibition test. Furthermore, crossreactivity between pork meat and dog dander extract was also noted. Taken together, the diagnosis of porkcat syndrome was made, and both cats and dogs were suggested to have led to the sensitization. The patient was advised to only eat well-cooked pork, and has been followed thereafter without additional reactions. The previously reported cases of this syndrome developed during adolescence and young adulthood because a considerable period from the sensitization to the development cross-reactivity with pork meat is required. To our best knowledge, this is the youngest reported case of pork-cat syndrome among English and Japanese literatures. The nomenclature of this syndrome as pet animal-meat syndrome improves the understanding of the underlying pathogenesis of cross-reactivity between animal albumins and meat albumins.

The thymus and activation-regulated chemokine (TARC) level in serum at an early stage of a drug eruption is a prognostic biomarker of severity of systemic inflammation.

BACKGROUND: In severe drug eruptions, precise evaluation of disease severity at an early stage is needed to start appropriate treatment. It is not always easy to diagnose these conditions at their early stage. In addition, there are no reported prognostic biomarkers of disease severity in drug eruptions. The aim of this study was to test whether the thymus and activation-regulated chemokine (TARC) level in serum at an early stage of a drug eruption can serve as a prognostic biomarker of systemic inflammation. METHODS: Study participants included 76 patients who received a diagnosis of a drug eruption, one of the following: drug rash with eosinophilia and systemic symptoms/drug-induced hypersensitivity syndrome, maculopapular exanthema, and erythema multiforme. Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) was eliminated in this study because scoring system for evaluating the severity was established. Correlation coefficients between serum TARC levels and indicators of systemic inflammation, including the neutrophil-to-lymphocyte ratio, Glasgow prognostic score, modified systemic inflammatory response syndrome (mSIRS) score, and C-reactive protein in serum were evaluated. RESULTS: Serum TARC levels positively correlated with the neutrophil-to-lymphocyte ratio, Glasgow prognostic score, mSIRS score, C-reactive protein, albumin, white blood cell count, body temperature, and pulse rate. TARC levels negatively correlated with systolic blood pressure. Among these parameters, the mSIRS score showed strong correlation (correlation coefficient: 0.68). CONCLUSIONS: Serum TARC levels correlate well with indicators of systemic inflammation and of disease severity among patients with a drug eruption except SJS/TEN. Serum TARC may be a prognostic biomarker of severity of inflammation in drug eruptions.

Efficacy and safety of omalizumab for the treatment of refractory chronic spontaneous urticaria in Japanese patients: Subgroup analysis of the phase 3 POLARIS study.

BACKGROUND: Omalizumab, a humanized anti-IgE monoclonal antibody, proved efficacious and well tolerated in patients with chronic spontaneous urticaria (CSU) refractory to H1 antihistamines (H1AH) in the POLARIS study (NCT02329223), a randomized, double-blind, placebo-controlled trial in East Asian patients. However, data in Japanese patients, who have specific baseline characteristics (e.g., low angioedema incidence, different background medications) that may impact clinical outcomes, are lacking. This pre-specified analysis presents additional patient-level data over time, pharmacokinetic and pharmacodynamics data for omalizumab and IgE, and efficacy and safety data for omalizumab in Japanese patients. METHODS: Japanese patients (N = 105) were randomized 1:1:1 to omalizumab 300 mg, 150 mg, or placebo by subcutaneous injection every 4 weeks. Efficacy and safety were assessed primarily based on changes from baseline to Week 12 in weekly itch-severity scores (ISS7) and weekly urticaria activity scores (UAS7), and incidence of adverse events (AEs), respectively. Patient-level UAS7 data over time were also reviewed. RESULTS: At Week 12, least squares mean (LSM) changes from baseline in ISS7 were greater with omalizumab vs. placebo (-9.54 and -7.29 for omalizumab 300 mg and 150 mg, respectively, vs. placebo [-5.17]). Corresponding LSM changes from baseline in UAS7 were -21.61 and -15.59 (vs. placebo [-10.88]). Most responders in the omalizumab 300 mg group displayed improvement of disease activity within 2-4 weeks and had well-controlled symptoms during the treatment period. Overall AE incidence was similar across treatment arms. CONCLUSIONS: This subgroup analysis demonstrated that omalizumab is a well-tolerated, beneficial option for treatment of CSU in H1AH-refractory Japanese patients.

Serum TARC levels are strongly correlated with blood eosinophil count in patients with drug eruptions.

BACKGROUND: This study aims to evaluate the relationship between serum thymus and activation-regulated chemokine (TARC) levels with various clinicopathological conditions in patients with drug eruptions. The value of TARC in diagnosing drug-induced hypersensitivity syndrome (DIHS) was also examined. METHODS: Study participants included 84 patients who presented with generalized eruptions suspected to be drug-related, including DIHS, Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN), maculopapular exanthema (MPE), erythema multiforme (EM), erythroderma, and toxicoderma. The correlation coefficients between serum TARC levels and clinical parameters in peripheral blood samples were calculated. RESULTS: Serum TARC levels in patients with DIHS were higher than those found in patients with SJS/TEN, MPE, EM, and toxicoderma. TARC levels had 100% sensitivity and 92.3% specificity in diagnosing DIHS, with a threshold value of 13,900 pg/mL. Serum TARC levels positively correlated with age, white blood cell (WBC) count, neutrophil count, eosinophil count, monocyte count, atypical lymphocyte (Aty-ly) count, serum blood urea nitrogen (BUN) levels, and creatinine (Cr) levels. It negatively correlated with serum total protein (TP), albumin (Alb), and estimated glomerular filtration rate (eGFR). Among these clinical parameters, blood eosinophil counts were most strongly correlated with serum TARC levels, with a correlation coefficient of 0.53. CONCLUSIONS: Serum TARC levels are well correlated with blood eosinophil counts in patients with generalized drug eruptions, indicating that Th2-type immune reactions underlie TARC production. Serum TARC measurements also have potent diagnostic value for DIHS, with high sensitivity and specificity.

A new reliable method for detecting specific IgE antibodies in the patients with immediate type wheat allergy due to hydrolyzed wheat protein: correlation of its titer and clinical severity.

BACKGROUND: Immediate-type wheat allergy caused by a specific hydrolyzed wheat protein (HWP-IWA), Glupearl 19S (GP19S), typically develops food-dependent exercise-induced anaphylaxis (FDEIA), but is different from conventional FDEIA, or simple wheat allergy in many aspects. The skin prick test (SPT) is considered to be the most effective method for diagnosis of HWP-IWA. As SPT is a relatively qualitative method, we developed quantitative and high-throughput test method for HWP-IWA. METHODS: An enzyme-linked immunosorbent assay (ELISA)-based GP19S-specific IgE assay was tested using sera from 14 HWP-IWA and five conventional wheat-dependent exercise-induced anaphylaxis (CO-WDEIA) patients, as well as five healthy subjects. Then a validation study at five different institutions was carried out using sera from 10 HWP-IWA and five CO-WDEIA patients, as well as five healthy subjects different from the previous studies. RESULTS: The mean unit values converted from measured absorbance of ELISA were 68.3, 1.3 and 1.1 respectively. Furthermore, the validation study revealed reproducible results across all five institutions, with the standard deviation (SD) being 0.3-0.4 for the healthy group, 0.2-0.6 for the CO-WDEIA group, and 3.8-9.6 for HWP-IWA group except for one case. One case of HWP-IWA was excluded from analysis due to the high SD of 53.3 units, indicating that samples with a unit value > 100.0 will affect inter-laboratory reproducibility. CONCLUSIONS: Our findings suggest that the ELISA-based GP19S-specific IgE assay can be used to test HWP-IWA using venous blood samples, except for those with a unit value > 100.0.

Higher allergenicity of high molecular weight hydrolysed wheat protein in cosmetics for percutaneous sensitization.

BACKGROUND: Wheat protein derivatives are used in a variety of products worldwide. Gluten is commercially used 'as is' or with modifications such as hydrolysis, which is carried out to overcome its insolubility. Several cases of contact urticaria following exposure to hydrolysed wheat protein (HWP) in cosmetics or of anaphylaxis caused by deamidated gluten in food or non-food products have been described. OBJECTIVES: To evaluate the types of HWP that have higher allergenicity for percutaneous sensitization. METHODS: We enrolled 7 patients with wheat-dependent exercise-induced anaphylaxis who had been sensitized to HWP primarily through the percutaneous and/or the rhinoconjunctival route by using facial soap containing HWP. Reaction to wheat proteins was confirmed by IgE immunoblotting and basophil CD203c expression with six HWP variants. RESULTS: The IgE of all the patients reacted to HWPs composed of large polypeptide aggregates. High molecular weight (MW) HWPs were also found to induce significant enhancement of basophil CD203c expression. CONCLUSIONS: HWPs composed of large polypeptide aggregates possibly induce sensitization to a greater degree than lower-MW HWPs. Basophil surface CD203c expression is useful for evaluating the allergenicity of HWPs.