Risk Factors for Anaphylaxis in Children Allergic to Peanuts.

Background and Objectives: A peanut allergy is the most common single cause of anaphylaxis in children. The risk factors for anaphylaxis in children with a peanut allergy are not well defined. Therefore, we aimed to identify epidemiological, clinical, and laboratory characteristics of children with a peanut allergy that may predict the severity of the allergic reaction and anaphylaxis. Materials and Methods: We conducted a cross-sectional study and included 94 children with a peanut allergy. Allergy testing was performed, including skin prick testing and the determination of specific IgE levels to peanuts and their Ara h2 component. In case of discordance between patient history and allergy testing, an oral food challenge with peanuts was performed. Results: Anaphylaxis and moderate and mild reactions to peanuts occurred in 33 (35.1%), 30 (31.9%), and 31 (33.0%) patients, respectively. The severity of the allergic reaction was only weakly correlated (p = 0.04) with the amount of peanuts consumed. The median number of allergic reactions to peanuts was 2 in children with anaphylaxis compared to 1 in other patients (p = 0.04). The median level of specific IgE to Ara h2 was 5.3 IU/mL in children with anaphylaxis compared to 0.6 IU/mL and 10.3 IU/mL in children with mild and moderate peanut allergies (p = 0.06). The optimal cutoff for distinguishing between anaphylaxis and a less severe allergic reaction to peanuts was a specific IgE Ara h2 level of 0.92 IU/mL with 90% sensitivity and 47.5% specificity for predicting anaphylaxis (p = 0.04). Conclusions: Epidemiological and clinical characteristics of the patient cannot predict the severity of the allergic reaction to peanuts in children. Even standard allergy testing, including component diagnostics, is a relatively poor predictor of the severity of an allergic reaction to peanuts. Therefore, more accurate predictive models, including new diagnostic tools, are needed to reduce the need for oral food challenge in most patients.

Ara h 2-specific IgE epitope-like peptides inhibit the binding of IgE to Ara h 2 and suppress lgE-dependent effector cell activation.

BACKGROUND: Clinical and experimental analyses indicate a pathognomonic role for allergen IgE crosslinking through epitope-paratope interactions as a major initial step in the cascade leading to effector cell activation and clinical manifestations of lgE-mediated food allergies. We aimed to undertake the initial development and assessment of Ara h 2-specific IgE epitope-like peptides that can bind to allergen-specific IgE paratopes and suppress effector cell activation. METHODS: We performed biopanning, screening, IgE binding, selection and mapping of peptides. We generated synthetic peptides for use in all functional experiments. ImmunoCAP inhibition, basophil and mast cell activation tests, with LAD2 cells, a human mast cell line were performed. Twenty-six children or young adults who had peanut allergy were studied. RESULTS: We identified and selected three linear peptides (DHPRFNRDNDVA, DHPRYGP and DHPRFST), and immunoblot analyses revealed binding to lgE from peanut-allergic individuals. The peptide sequences were aligned to the disordered region corresponding to the loop between helices 2 and 3 of Ara h 2, and conformational mapping showed that the peptides match the surface of Ara h 2 and h 6 but not other peanut allergens. In ImmunoCAP inhibition experiments, the peptides significantly inhibit the binding of IgE to Ara h 2 (p < .001). In basophil and mast cell activation tests, the peptides significantly suppressed Ara h 2-induced effector cell activation (p < .05) and increased the half-maximal Ara h 2 effective concentration (p < .05). Binding of the peptides to specific IgEs did not induce activation of basophils or mast cells. CONCLUSIONS: These studies show that the indicated peptides reduce the allergenic activity of Ara h 2 and suppress lgE-dependent basophil and mast cell activation. These observations may suggest a novel therapeutic strategy for food allergy based on epitope-paratop blocking.

The Variants in the 3' Untranslated Region of the Matrix Metalloproteinase 9 Gene as Modulators of Treatment Outcome in Children with Asthma.

PURPOSE: The maintaining of asthma control is difficult due to high variability in response to therapy among patients. Since matrix metalloproteinase 9 (MMP9) is implicated in inflammation and remodeling of asthmatic airways, it could be associated with adequate response to asthma therapy. The aim of this study was to investigate whether variants in 3' end of the MMP9 gene are associated with clinical phenotype and responsiveness to treatment in children with asthma. METHODS: The study included 127 asthmatic children from Slovenia. Variants in the 3' end of the MMP9 gene were analyzed by direct DNA sequencing and the obtained results were correlated with clinical parameters. RESULTS: Two variants were detected, rs13925 and rs20544. For the variant rs20544, statistically significant difference in airway hyperresponsiveness (p = 0.011) and asthma control (p = 0.049) between genotypes was found. Patients with TT genotype had lower airway sensitivity, and after 12 months of treatment showed significant improvement in Asthma Control Test (ACT) scores compared to CC and CT genotype. For the variant rs13925, the association with lung function was observed. The carriers of A allele showed noticeable improvement of lung function after the first 6 months of treatment in comparison to the carriers of G allele (p = 0.046). CONCLUSION: The main finding of our study is the association of MMP9 genotypes rs20544 TT and rs13925 AA and AG with better asthma control, and indirectly better response to treatment. Based on these results, MMP9 deserves further research as a potential predictive biomarker for asthma.

The relevance of basophil allergen sensitivity testing to distinguish between severe and mild peanut-allergic children.

BACKGROUND: Peanut sensitization is common in children. However, it is difficult to assess which children will react mildly and which severely. This study evaluated the relevance of basophil allergen sensitivity testing to distinguish the severity of peanut allergy in children. METHODS: Twenty-seven peanut-sensitized children with symptoms varying from mild symptoms to severe anaphylaxis underwent peanut CD63 dose-response curve analysis with the inclusion of basophil allergen sensitivity calculation (CD-sens) and peanut component immunoglobulin E (IgE) testing. RESULTS: Eleven children who had experienced anaphylaxis to peanuts showed a markedly higher peanut CD63 response at submaximal allergen concentrations and CD-sens (median 1,667 vs. 0.5; p < 0.0001) than 16 children who experienced a milder reaction. Furthermore, a negative or low CD-sens to peanuts unambiguously excluded anaphylactic peanut allergy. Children with anaphylaxis have higher levels of Ara h 1, 2, 3 and 9 IgE, but comparable levels of IgE to Ara h 8 and whole-peanut extract. The diagnostic specificity calculated with a receiver operating characteristic analysis reached 100% for CD-sens and 73% for Ara h 2. CONCLUSIONS: We demonstrated that severe peanut allergy is significantly associated with higher basophil allergen sensitivity. This cellular test should facilitate a more accurate diagnosis of peanut allergy.

Asthma treatment outcome in children is associated with vascular endothelial growth factor A (VEGFA) polymorphisms.

BACKGROUND: Asthma is a common chronic disease characterized by airway inflammation and structural remodeling. Vascular endothelial growth factor (VEGF), a major regulator of angiogenesis, is elevated in asthma patients. VEGF contributes to airway responsiveness and remodeling. It has been shown that treatment of asthma patients decreases VEGF levels, and inhibition of VEGF diminishes asthma symptoms in mice. Therefore, polymorphisms in the vascular endothelial growth factor A (VEGFA) gene might be associated with asthma treatment response. METHODS: This study enrolled 131 children with asthma treated with different therapies - specifically, the inhaled corticosteroid (ICS) fluticasone propionate or the leukotriene receptor antagonist (LTRA) montelukast. We performed an association analysis between improvement of lung function - assessed by measurement of the percentage of the predicted forced expiratory volume in 1 second (%predicted FEV(1)), the ratio between the FEV(1) and the forced vital capacity (FEV(1)/FVC) after 6 and 12 months of treatment, and asthma control after 12 months of treatment - and two polymorphisms, rs2146323 and rs833058, in the VEGFA gene. RESULTS: Polymorphism rs2146323 A>C in VEGFA was associated with response to ICS therapy. Asthma patients with the AA genotype had a greater improvement in the %predicted FEV(1) than those with the AC or CC genotype (p = 0.018). Conversely, the AA genotype in rs2146323 was associated with uncontrolled asthma in patients regularly receiving LTRA therapy (p = 0.020) and a worse FEV(1)/FVC ratio in patients who episodically used LTRA therapy (p = 0.044). Furthermore, polymorphism rs833058 C>T was associated with treatment response to episodically used LTRA therapy. A subgroup of patients with the TT genotype had an improvement in the %predicted FEV(1), compared with no improvement in patients with the CT or CC genotype (p = 0.029). CONCLUSIONS: Our results showed that treatment response to commonly used asthma therapies (ICS or LTRA) is associated with polymorphisms rs2146323 and rs833058 in VEGFA. With additional replication of this preliminary study, our findings could contribute to the development of individualized asthma therapy.

A colloid cyst of the third ventricle -- the cause of episodic headache and sudden unexpected death in an adolescent girl.

An 18-year-old girl was found dead in her bed. The autopsy revealed a colloid cyst of the third ventricle. The cyst obstructed the flow of cerebrospinal fluid, leading to prominent internal hydrocephalus with consecutive brain edema and compression of the caudal medulla at the foramen magnum. The girl's only previous complaints were episodic headaches for the previous 2-3 years. Computed tomography and magnetic resonance imaging were not performed prior to her death. This case report highlights the importance of early diagnosis of colloid cyst of the third ventricle and the need to perform computed tomography and magnetic resonance imaging in patients with episodic headaches even when they show no neurologic deficit. Although it is a very rare disorder, it should be included in the differential diagnosis of headaches in children and young adults, and also in the differential diagnosis of conditions causing increased intracranial pressure, in view of the life-saving management required to prevent a fatal outcome.