Safety of Oral Food Challenge for Individuals with Low Egg White and Ovomucoid-Specific IgE Antibodies.

INTRODUCTION: During an oral food challenge (OFC), there is a risk of adverse reactions, including anaphylaxis. Therefore, the physician should carefully conduct the OFC. This study aimed to evaluate the OFC results in individuals with low levels of egg white (EW)- and ovomucoid (OVM)-specific immunoglobulin E (sIgE) and the safety of a hen's egg (HE) OFC in these individuals. METHODS: A total of 2,058 individuals with low EW- or OVM-sIgE underwent HE-OFC at two institutions in Kumamoto prefecture, located in the western area of Japan, between January 1, 2017, and December 31, 2021, within 1 year of recorded sIgE measurements. The ImmunoCAP systems were used to measure sIgEs. The HE-OFC test was performed according to the 2017 Food Allergy Guidelines in an open and unblinded method. RESULTS: Five hundred and one individuals (24.3%) had low EW-sIgE levels (class 2 or lower), and 926 (45.0%) had low OVM-sIgE levels (class 2 or lower). Individuals with low EW-sIgE had lower total IgE and OVM-sIgE than did those with high EW-sIgE (greater than class 2). Those with low OVM-sIgE had lower total IgE and EW-sIgE than did those with high OVM-sIgE (greater than class 2). Among the individuals with low EW-sIgE, 86.4% (433/501 cases) passed the OFC without symptoms. Among the individuals with low OVF-sIgE, 82.6% (765/926 cases) passed the OFC without symptoms. CONCLUSION: More than 80% of individuals with suspected IgE-dependent HE allergy and low levels of EW- or OVM-specific IgE were able to consume at least a small amount of HE. As the OFC results are independent of the loading dose in cases with low EW- or OVM-sIgE, a medium-dose HE-OFC may be performed safely in individuals with no history of anaphylaxis.

Newly emerged genotypes of highly pathogenic H5N8 avian influenza viruses in Kagoshima prefecture, Japan during winter 2020/21.

During the 2020/21 winter season, 29 and 10 H5N8 high pathogenicity avian influenza viruses (HPAIVs) were isolated from environmental water and wild birds, respectively, in Kagoshima prefecture, Japan. Furthermore, seven subtypes of low pathogenicity avian influenza viruses (LPAIVs) were also isolated; H1N1, H2N9, H3N2, H3N6, H3N8, H4N6, and H6N6 subtypes. While the H5 hemagglutinin (HA) genes of the G1 cluster were isolated throughout the winter season, those of the G2 cluster were also detected in late winter, suggesting that H5 HPAIVs possessing H5 HA genes from the two different clusters were individually introduced into Kagoshima prefecture. Intriguingly, genetic constellations revealed that the H5N8 HPAIVs could be classified into six genotypes, including four previously reported genotypes (E1, E2, E3, and E7), and two new genotypes (tentatively named E8 and E9). The PB1 and PA gene segments of genotypes E8 and E9 shared high similarity with those of LPAIVs, whereas the remaining gene segments were close to those of genotype E1. Furthermore, LPAIVs whose PA gene segment was close to that of genotype E9 were isolated from the environmental water. Overall, we revealed that various HPAIV genotypes circulated in Kagoshima prefecture during the 2020/21 winter season. This study highlights the importance of monitoring both HPAIV and LPAIV to better understand AIV ecology in migratory waterfowl populations.

Genetic Characterization of Avian Influenza Viruses Isolated from the Izumi Plain, Japan in 2019/20 Winter Season.

The Izumi plain in the Kagoshima Prefecture, Japan, is known as an overwintering site for more than 30,000 migratory waterfowl, including endangered crane species. We previously reported that environmental water samples, from artificial wet paddies created as crane roost sites on the Izumi plain, are useful for avian influenza virus (AIV) surveillance. During the 2019/20 winter season, we collected 238 water samples from the crane roost sites and isolated 22 AIVs of six subtypes: one H1N1, one H3N2, seven H3N8, four H4N6, nine H6N6, and one H11N2 subtypes. Genetic analyses revealed that AIVs of the same subtype isolated from the Izumi plain during a single winter season exhibited multiple genetic constellations. Furthermore, phylogenetic analyses suggested that our H3N2 isolate may be a genetic reassortant between close relatives to our H3N8 and H11N2 isolates. Our study highlighted the importance of monitoring AIV circulation to better understand AIV ecology in migratory waterfowl populations.

Transition in genetic constellations of H3N8 and H4N6 low-pathogenic avian influenza viruses isolated from an overwintering site in Japan throughout different winter seasons.

The Izumi plain in Kagoshima Prefecture, Japan, is an overwintering site for migratory ducks and endangered cranes. We have surveyed avian influenza viruses (AIVs) in this area since 2012 and isolated low-pathogenic AIVs (LPAIVs) of various subtypes every winter season. H3N8 LPAIVs were isolated during the 2012/13 and 2016/17 seasons, and H4N6 LPAIVs were isolated during the 2012/13 and 2013/14 seasons. In the 2017/18 season, one H3N8 and two H4N6 LPAIV strains were isolated from environmental water samples. Genetic and phylogenetic analysis for each gene segment from these H3N8 and H4N6 LPAIVs suggested that our isolates were genetic reassortants generated by intermixing between AIVs circulating not only in Eurasia but also in Africa and/or North America. Comparison of the genetic constellations of our three isolates with their counterparts isolated during previous seasons from the Izumi plain revealed a drastic transition in the genetic constellations of both subtypes. These findings emphasize the importance of continuous surveillance of AIVs on the Izumi plain.

Phylogenetic variations of highly pathogenic H5N6 avian influenza viruses isolated from wild birds in the Izumi plain, Japan, during the 2016-17 winter season.

During the 2016-2017 winter season, we isolated 33 highly pathogenic avian influenza viruses (HPAIVs) of H5N6 subtype and three low pathogenic avian influenza viruses (LPAIVs) from debilitated or dead wild birds, duck faeces, and environmental water samples collected in the Izumi plain, an overwintering site for migratory birds in Japan. Genetic analyses of the H5N6 HPAIV isolates revealed previously unreported phylogenetic variations in the PB2, PB1, PA, and NS gene segments and allowed us to propose two novel genotypes for the contemporary H5N6 HPAIVs. In addition, analysis of the four gene segments identified close phylogenetic relationships between our three LPAIV isolates and the contemporary H5N6 HPAIV isolates. Our results implied the co-circulation and co-evolution of HPAIVs and LPAIVs within the same wild bird populations, thereby highlighting the importance of avian influenza surveillance targeting not only for HPAIVs but also for LPAIVs.

The Oral Provocation Test for Raw Egg in Patients with Hen Egg Allergy.

BACKGROUND: Many researchers have made efforts to develop diagnostic tools for predicting the outcome of oral food challenges (OFCs). The aim of this study was to assess the diagnostic value of the skin prick test (SPT) and blood-specific IgE concentrations based on the outcome of the OFCs for heated and raw hen egg. METHODS: This study included 103 children with suspected hen egg allergy (HEA; median age 23 months, range 10-155; 72 boys, 31 girls). Forty-three patients were diagnosed with HEA by OFC. Of 60 patients who tolerated heated egg white (HEW), 22 underwent the OFC for raw hen egg and 7 developed adverse reactions after ingesting raw egg. Their wheal diameters and specific IgE levels for egg white and ovomucoid were determined. RESULTS: Wheal diameters as well as blood-specific IgE levels for egg white and ovomucoid were significantly larger in children with positive OFC results for HEW than in those with negative results. However, there were no significant differences between the positive and negative test results for raw hen egg white (REW) in wheal diameter or blood-specific IgE levels. CONCLUSIONS: The SPT and blood-specific IgE can be used to diagnose HEA. However, the provocation test for REW in children without HEW allergy is important because the values of SPT and specific IgE were not significantly different between children with and without raw egg allergy.

Evaluation of the skin-prick test for predicting the outgrowth of cow's milk allergy.

BACKGROUND: Although considerable efforts have been made to develop diagnostic tools for predicting the outcome of oral food challenges, tests for predicting the outgrowth of food allergies are lacking. OBJECTIVE: The aim of this study was to assess the diagnostic value of the wheal size and skin index (SI) (the ratio of an allergen-induced wheal to a histamine-induced wheal diameter) of the skin-prick test based on the outcome of a controlled oral provocation test for cow's milk. Moreover, we assessed whether wheal size and/or SI were useful for predicting the outgrowth of cow's milk allergy (CMA). METHODS: This study included 135 children with suspected CMA. Eighty-one patients were definitely diagnosed by oral provocation tests for cow's milk, and their wheal diameters, SIs, and cow milk's-specific serum immunoglobulin E concentrations were determined. RESULTS: The wheal diameters were significantly larger and the SIs significantly higher in children with positive oral provocation test results than in those with negative test results. We found that 50% of the patients were expected to be able to drink cow's milk by age 5 years. In these patients, the wheal diameters were significantly smaller and the SIs significantly lower at the time of CMA outgrowth than at the time of diagnosis, whereas these values were apt to increase in patients who did not outgrow CMA, with no significant difference. CONCLUSIONS: The skin-prick test can be used to diagnose CMA and predict CMA outgrowth. A wheal diameter of 8 mm or/and an SI of 1.0 is informative, not only in diagnosing CMA but also in predicting a natural CMA outgrowth.

Enhanced CCL26 production by IL-4 through IFN-gamma-induced upregulation of type 1 IL-4 receptor in keratinocytes.

A Th2 cytokine, IL-4, induces various chemokines from epidermal keratinocytes which play crucial roles in the pathogenesis of skin disorders such as atopic dermatitis. In contrast, the role of IFN-gamma, a Th1 cytokine, on eosinophilic skin inflammation is unclear. This study investigated the effects of IFN-gamma on IL-4-induced production of eotaxin-3/CCL26, a potent chemoattractant to eosinophils, in normal human epidermal keratinocytes (NHEK). When the cells were stimulated with IL-4 and IFN-gamma simultaneously, IL-4-induced CCL26 production was attenuated. In contrast, prior stimulation with IFN-gamma enhanced IL-4-induced CCL26 production. NHEK constitutively expressed type 1 IL-4 receptor, and expression at the cell surface was upregulated by stimulation with IFN-gamma. This upregulation resulted in an enhanced IL-4-mediated cellular signal. These results indicate that IFN-gamma has opposite effects on IL-4-induced CCL26 production in NHEK depending on the time of exposure. Thus, changes in IL-4R expression by IFN-gamma might modulate eosinophilic skin inflammation.

Squamous cell carcinoma-related antigen in children with acute asthma.

BACKGROUND: Increased serum levels of squamous cell carcinoma-related antigen (SCCA) have been observed in patients with allergic disorders, such as atopic dermatitis and bronchial asthma. T(H)2 cytokines, which are known to be involved in the pathogenesis of allergic disorders, stimulate new synthesis of SCCA in cultured human airway epithelial cells. OBJECTIVE: To investigate whether SCCA levels increase during acute exacerbations of asthma in children and whether the T(H)2 cytokines, interleukin 4 (IL-4) and IL-13, are associated with SCCA levels. METHODS: Serum levels of SCCA, IL-4, and IL-13 were measured by enzyme immunoassay during the acute phase of an asthma exacerbation (on hospital admission) and in the recovery phase (after symptoms had subsided). RESULTS: In the 35 children who participated in this study, serum levels of SCCA were significantly elevated in the acute phase (mean +/- SD, 3.09 +/- 2.03 ng/mL) compared with the recovery phase (mean +/- SD, 1.47 +/- 0.64 ng/mL) of an asthma exacerbation (P < .001). In 12 children, the IL-13 levels were observed to correlate with SCCA levels during the recovery phase (r = 0.68, P = .02) but not during the acute phase of an asthma exacerbation. CONCLUSIONS: Serum SCCA levels increase during the acute phase of an asthma exacerbation. During this phase, the increased synthesis of SCCA is not associated with IL-13 but rather mediated by other undefined stimuli. IL-13 may contribute to the basal production of SCCA in asthmatic children.

Regulatory mechanisms of Th2 cytokine-induced eotaxin-3 production in bronchial epithelial cells: possible role of interleukin 4 receptor and nuclear factor-kappaB.

BACKGROUND: Several cytokine combinations have been shown to induce eotaxins in bronchial epithelium. The mechanism for differential regulation of eotaxin expression remains unclear. OBJECTIVE: To investigate the regulatory mechanisms of eotaxin-3 production vs eotaxin-1 production in cultured bronchial epithelium. METHODS: Messenger RNA (mRNA) expression levels of eotaxin-1, eotaxin-2, and eotaxin-3 in a human bronchial epithelial cell line (BEAS-2B) and a normal human bronchial epithelial cell were examined using reverse transcriptase-polymerase chain reaction. Protein production was determined by enzyme-linked immunosorbent assay. Receptor expression was examined by flow cytometry. Phosphorylation of signal transducer and activator of transcription factor 6 (STAT6) was examined by immunoblotting. RESULTS: Eotaxin-1 and eotaxin-3, but not eotaxin-2, mRNA expressions were induced by stimulation with interleukin (IL) 13 or IL-4. However, eotaxin-3 was the only protein detected after stimulation. A consistent 10-fold difference in the potency of IL-13- and IL-4-mediated induction of eotaxin-3 mRNA expression was observed. Interleukin 4 induced more potent induction of STAT6 phosphorylation compared with IL-13. The BEAS-2B cells were observed to express types 1 and 2 IL-4 receptors. Pretreatment with tumor necrosis factor a enhanced IL-4-induced eotaxin-1, but not eotaxin-3, mRNA expression. An inhibitor of nuclear factor-KB inhibited IL-13- and IL-4-induced eotaxin-1 gene expressions. However, it enhanced eotaxin-3 gene expression. CONCLUSIONS: These results suggest that differences in the potency of IL-13- and IL-4-mediated induction of eotaxin-3 might be explained by expression of types 1 and 2 IL-4 receptors in bronchial epithelium. Differences in eotaxin-1 and eotaxin-3 mRNA and protein expression might be due to differential effects of nuclear factor-kappaB on gene expression.

Upregulation of interleukin-4 receptor by interferon-gamma: enhanced interleukin-4-induced eotaxin-3 production in airway epithelium.

Airway epithelial cells produce a number of chemokines, including eotaxins. Among the three known eotaxins, T helper (Th) type 2 cytokines have been observed to induce the expression of eotaxin-3 mRNA. This study investigated the effect of interferon (IFN)-gamma, a Th1 cytokine, on Th2 cytokine-induced eotaxin-3 production in a bronchial epithelial cell line, BEAS-2B. BEAS-2B cells produced eotaxin-3 after stimulation with the Th2 cytokines interleukin (IL)-13 and IL-4. When BEAS-2B cells were cultured with varying concentrations of IFN-gamma for 24 h, dose-dependent inhibition of Th2 cytokine-induced eotaxin-3 mRNA expression and protein production was observed. This was associated with downregulation of signal transducer and activator of transcription 6 activation. On the other hand, 2-d pretreatment of BEAS-2B cells with IFN-gamma dose-dependently enhanced Th2 cytokine-induced eotaxin-3 mRNA expression and production. IFN-gamma also increased the mRNA expression and protein production of IL-4 receptor (R) alpha in a time- and dose-dependent manner. In addition, IL-2Rgamma, a component of the type 1 IL-4R, was also upregulated by IFN-gamma. These results indicate that IFN-gamma has opposite effects on Th2 cytokine-induced eotaxin-3 production in BEAS-2B cells, depending on the length of exposure. Because high levels of IFN-gamma are produced during viral infection, airway viral infection may affect allergic airway inflammation in vivo by modulation of eotaxin-3 production.