Mapping Sequential IgE-Binding Epitopes on Major and Minor Egg Allergens.

INTRODUCTION: Molecular studies of hen's egg allergens help define allergic phenotypes, with IgE to sequential (linear) epitopes on the ovomucoid (OVM) protein associated with a persistent disease. Epitope profiles of other egg allergens are largely unknown. The objective of this study was to construct an epitope library spanning across 7 allergens and further evaluate sequential epitope-specific (ses-)IgE and ses-IgG4 among baked-egg reactive or tolerant children. METHODS: A Bead-Based Epitope Assay was used to identify informative IgE epitopes from 15-mer overlapping peptides covering the entire OVM and ovalbumin (OVA) proteins in 38 egg allergic children. An amalgamation of 12 B-cell epitope prediction tools was developed using experimentally identified epitopes. This ensemble was used to predict epitopes from ovotransferrin, lysozyme, serum albumin, vitellogenin-II fragment, and vitellogenin-1 precursor. Ses-IgE and ses-IgG4 repertoires of 135 egg allergic children (82 reactive to baked-egg, the remaining 52 tolerant), 46 atopic controls, and 11 healthy subjects were compared. RESULTS: 183 peptides from OVM and OVA were screened and used to create an aggregate algorithm, improving predictions of 12 individual tools. A final library of 65 sequential epitopes from 7 proteins was constructed. Egg allergic children had higher ses-IgE and lower ses-IgG4 to predominantly OVM epitopes than both atopic and healthy controls. Baked-egg reactive children had similar ses-IgG4 but greater ses-IgE than tolerant group. A combination of OVA-sIgE with ses-IgEs to OVM-023 and OVA-028 was the best predictor of reactive phenotype. CONCLUSION: We have created a comprehensive epitope library and showed that ses-IgE is a potential biomarker of baked-egg reactivity.

Immunodeficiency and bone marrow failure with mosaic and germline TLR8 gain of function.

Inborn errors of immunity (IEI) are a genetically heterogeneous group of disorders with a broad clinical spectrum. Identification of molecular and functional bases of these disorders is important for diagnosis, treatment, and an understanding of the human immune response. We identified 6 unrelated males with neutropenia, infections, lymphoproliferation, humoral immune defects, and in some cases bone marrow failure associated with 3 different variants in the X-linked gene TLR8, encoding the endosomal Toll-like receptor 8 (TLR8). Interestingly, 5 patients had somatic variants in TLR8 with <30% mosaicism, suggesting a dominant mechanism responsible for the clinical phenotype. Mosaicism was also detected in skin-derived fibroblasts in 3 patients, demonstrating that mutations were not limited to the hematopoietic compartment. All patients had refractory chronic neutropenia, and 3 patients underwent allogeneic hematopoietic cell transplantation. All variants conferred gain of function to TLR8 protein, and immune phenotyping demonstrated a proinflammatory phenotype with activated T cells and elevated serum cytokines associated with impaired B-cell maturation. Differentiation of myeloid cells from patient-derived induced pluripotent stem cells demonstrated increased responsiveness to TLR8. Together, these findings demonstrate that gain-of-function variants in TLR8 lead to a novel childhood-onset IEI with lymphoproliferation, neutropenia, infectious susceptibility, B- and T-cell defects, and in some cases, bone marrow failure. Somatic mosaicism is a prominent molecular mechanism of this new disease.

Development and Application of a Functional Human Esophageal Mucosa Explant Platform to Eosinophilic Esophagitis.

There is an increasing prevalence of esophageal diseases but intact human tissue platforms to study esophageal function, disease mechanisms, and the interactions between cell types in situ are lacking. To address this, we utilized full thickness human donor esophagi to create and validate the ex vivo function of mucosa and smooth muscle (n = 25). Explanted tissue was tested for contractile responses to carbachol and histamine. We then treated ex vivo human esophageal mucosa with a cytokine cocktail to closely mimic the Th2 and inflammatory milieu of eosinophilic esophagitis (EoE) and assessed alterations in smooth muscle and extracellular matrix function and stiffening. We found that full thickness human esophagus as well as the individual layers of circular and longitudinal muscularis propria developed tension in response to carbachol ex vivo and that mucosa demonstrated squamous cell differentiation. Treatment of mucosa with Th2 and fibrotic cytokines recapitulated the majority of the clinical Eosinophilic Esophagitis Diagnostic Profile (EDP) on fluidic transcriptional microarray. Transforming growth factor-beta-1 (TGFß1) increased gene expression of fibronectin, smooth muscle actin, and phospholamban (p < 0.001). The EoE cocktail also increased stiffness and decreased mucosal compliance, akin to the functional alterations in EoE (p = 0.001). This work establishes a new, transcriptionally intact and physiologically functional human platform to model esophageal tissue responses in EoE.

Effects of the ß-agonist, isoprenaline, on the down-regulation, functional responsiveness and trafficking of ß2-adrenergic receptors with N-terminal polymorphisms.

The ß2-AR (ß2-adrenergic receptor) is an important target for respiratory and CVD (cardiovascular disease) medications. Clinical studies suggest that N-terminal polymorphisms of ß2-AR may act as disease modifiers. We hypothesized that polymorphisms at amino acids 16 and 27 result in differential trafficking and down-regulation of ß2-AR variants following ß-agonist exposure. The functional consequences of the four possible combinations of these polymorphisms in the human ß2-AR (designated ß2-AR-RE, ß2-AR-GE, ß2-AR-RQ and ß2-AR-GQ) were studied using site-directed mutagenesis and recombinant expression in HEK-293 cells (human embryonic kidney cells). Ligand-binding assays demonstrated that after 24 h exposure to 1 µM isoprenaline, isoforms with Arg16 (ß2-AR-RE and ß2-AR-RQ) underwent increased down-regulation compared with isoforms with Gly16 (ß2-AR-GE and ß2-AR-GQ). Consistent with these differences in down-regulation between isoforms, prolonged isoprenaline treatment resulted in diminished cAMP response to subsequent isoprenaline challenge in ß2-AR-RE relative to ß2-AR-GE. Confocal microscopy revealed that the receptor isoforms had similar co-localization with the early endosomal marker EEA1 following isoprenaline treatment, suggesting that they had similar patterns of internalization. None of the isoforms exhibited significant co-localization with the recycling endosome marker Rab11 in response to isoprenaline treatment. Furthermore, we found that prolonged isoprenaline treatment led to a higher degree of co-localization of ß2-AR-RE with the lysosomal marker LAMP1 (lysosome-associated membrane protein 1) compared with that of ß2-AR-GE. Taken together, these results indicate that a mechanism responsible for differential responses of these receptor isoforms to the ß-agonist involves differences in the efficiency with which agonist-activated receptors are trafficked to the lysosomes for degradation, or differences in degradation in the lysosomes.

Development and validation of educational materials for food allergy.

OBJECTIVE: To develop and validate a food allergy educational program. STUDY DESIGN: Materials developed through focus groups and parental and expert review were submitted to 60 parents of newly referred children with a prior food allergy diagnosis and an epinephrine autoinjector. The main outcome was correct demonstration of an autoinjector. RESULTS: The correct number of autoinjector activation steps increased from 3.4 to 5.95 (of 6) after training (P < .001) and was 5.47 at 1 year (P < .05). The mean score for comfort with using the autoinjector (7-point Likert scale) before the curriculum was 4.63 (somewhat comfortable) and increased to 6.23 after the intervention (P < .05) and remained elevated at 1 year (6.03). Knowledge tests (maximum 15) increased from a mean score of 9.2 to 12.4 (P < .001) at the initial visit and remained at 12.7 at 1 year. The annualized rate of allergic reactions fell from 1.77 (historical) the year prior, to 0.42 (P < .001) after the program. On a 7-point Likert scale, all satisfaction categories remained above a favorable mean score of 6: straight-forward, organized, interesting, relevant, and recommend to others. CONCLUSIONS: This food allergy educational curriculum for parents, now available online at no cost, showed high levels of satisfaction and efficacy.

Food allergy educational needs of pediatric dietitians: a survey by the Consortium of Food Allergy Research.

OBJECTIVE: To determine pediatric dietitians' self-reported proficiency, educational needs, and preferences regarding food allergy (FA) management. DESIGN AND SETTING: An Internet-based, anonymous survey was distributed to the Pediatric Nutrition Practice Group (PNPG) of the American Dietetic Association. PARTICIPANTS: Respondents (n = 311) were registered dietitians and members of the PNPG. ANALYSIS: Results are presented using descriptive statistics. Chi-square tests were applied for subgroup analyses. Percentage responses were calculated per question based on the number of respondents answering the question. RESULTS: On a 4-point scale of proficiency ("high," "moderate," "low," and "none"), respondents primarily rated themselves "moderate" for educating families, creating diets, and evaluating safe food items, and "low" for creating diagnostic food challenges. Education was primarily self-taught (75%). Preferences for future resources included handbooks (77%) and Web-based instructional programs (53%). On a 4-point scale ("very" to "not at all" needed) among practices that included >10% patients with FA, ratings of "very" were defined as need resources to update FA knowledge (87%) and need for a FA "tool kit" (84%). CONCLUSIONS AND IMPLICATIONS: Pediatric dietitians manage FA for a substantial patient base although their self-reported proficiency is overall only moderate. Dietitians would prefer and likely benefit from Internet-accessible management handbooks and patient handouts.

Food allergy education for school nurses: a needs assessment survey by the consortium of food allergy research.

Food allergy is increasing in school-age children. School nurses are a primary health care resource for children with food allergy and must be prepared to manage allergen avoidance and respond in the event of an allergic reaction. An anonymous survey was administered to school nurses attending their association meetings to determine their educational needs regarding children with food allergy. With 199 school nurses responding, their self-reported proficiency for critical areas of food allergy knowledge and management varied, with weaknesses identified particularly for emergency plan development, staff education, delegation, developing guidelines for banning foods and planning school trips. Nurses reported a high interest in obtaining educational materials in these areas and prefer video and Internet resources that could be promoted through professional organizations.

Relationship of body mass index with asthma indicators in head start children.

OBJECTIVE: To examine the relationship of body mass index (BMI) and asthma indicators on children with asthma in a Head Start (HS) program. METHODS: In this cross-sectional study (November 18, 2000, to December 12, 2003) of children aged 3 to 5 years with asthma, we compared the BMI data of HS asthmatic patients (n = 213) with the data of peer control subjects from a sample (n = 816) of the National Health and Nutrition Examination Survey aged 3 to 5 years and with children in prekindergarten in Arkansas public schools (n = 1,024). Parental reports of asthma symptoms, health care use, medication use, school days missed, and quality of life were used as indicators of asthma morbidity. Categorical analysis and chi2 tests were performed to examine the relationship between BMI and asthma morbidity. RESULTS: The prevalence of overweight (> or =95th percentile) was significantly higher in HS children with asthma compared with the National Health and Nutrition Examination Survey children (P < .001) and Arkansas prekindergarten children (P = .05). Compared with HS asthmatic children with a BMI less than the 85th percentile, HS asthmatic patients with a BMI of the 85th percentile or greater reported significantly more school days missed (P = .02), lifetime hospitalizations (P = .04), emergency department visits (P = .02), and activity limitations (P = .03) and fewer oral corticosteroid bursts (P = .04). There was also a trend for more daytime symptoms (P = .05) and lower quality of life (P = .06). No differences were observed in rescue (P = .28) or controller (P = .47) medications, environmental tobacco smoke exposure (P = .47), positive allergy test results (P = .85), and nighttime symptoms (P > .99). CONCLUSIONS: Having an increased BMI was associated with more asthma morbidity in this group of HS asthmatic patients. Despite the lack of a clear explanation for the link between asthma and BMI, our data suggest that an increased BMI significantly affects the well-being of young asthmatic patients and should be further addressed.

X-linked agammaglobulinemia: report on a United States registry of 201 patients.

X-linked agammaglobulinemia (XLA) is a primary immunodeficiency caused by mutations in the gene for Bruton tyrosine kinase (BTK) that result in the deficient development of B lymphocytes and hypogammaglobulinemia. Because the disorder is uncommon, no single institution has had sufficient numbers of patients to develop a comprehensive clinical picture of the disorder. Accordingly, a national registry of United States residents with XLA was established in 1999 to provide an updated clinical view of the disorder in a large cohort of patients. A total of 201 patients were registered by 66 physicians. The estimated birth rate for the 10-year period of 1988-1997 was 1/379,000. Infection was the most common initial clinical presentation (85%), followed by a positive family history (41%) and neutropenia (11%). Although the average age of diagnosis was younger in patients with a positive family history (mean, 2.59 yr) than in patients with a negative family history (mean, 5.37 yr) (p < 0.001), only 34.5% of patients with a positive family history at the time of their birth were diagnosed before clinical symptoms developed-that is, based on family history alone. Seventy percent of patients had at least 1 episode of otitis, 62% at least 1 episode of pneumonia, 60% at least 1 episode of sinusitis, 23% at least 1 episode of chronic/recurrent diarrhea, 21% at least 1 episode of conjunctivitis, 18% at least 1 episode of pyoderma and/or cellulitis, 11% at least 1 episode of meningitis/encephalitis, 10% at least 1 episode of sepsis, 8% at least 1 episode of septic arthritis, 6% at least 1 episode of hepatitis, and 3% at least 1 episode of osteomyelitis. Fourteen of 201 (6.9%) patients were dead at the time they were entered in the Registry. However, in a prospective 4 /4-year follow-up of living patients, only 3/80 (3.75%) patients died. Causes of death included disseminated enterovirus infection (n = 6), pulmonary insufficiency (n = 5), adenovirus infection (n = 1), sepsis (n = 1), acquired immunodeficiency disease syndrome (AIDS) (n = 1), myocarditis (n = 1), hepatitis (n = 2), and stem cell transplantation (n = 1).

Allergic fungal sinusitis in children.

BACKGROUND: Allergic fungal sinusitis (AFS) has been characterized in adults presenting with chronic sinusitis. Rare reports allude to a similar disease in children. OBJECTIVE: To characterize the features of AFS in children. METHODS: Children referred to otolaryngology clinics at Arkansas and LeBonheur Children's Hospitals for chronic sinusitis during a 12-year period were studied. This retrospective analysis reviews the following: clinical presentation, laboratory evaluations, radiographic and pathologic findings, and surgical intervention. Twenty patients (age range, 7-18 years; mean age, 12.5 years; median age, 16 years) met previously published criteria for AFS. Thirteen patients were male and 7 were female. Thirteen were African American and 7 were white. RESULTS: Presentation at diagnosis included the following: atopy (n = 20), nasal symptoms (n = 20), recurrent sinusitis (n = 18), nasal polyps (n = 18), recurrent headaches (n = 12), asthma (n = 11), proptosis (n = 10), and ocular symptoms (n = 10). All had radiographic evidence of sinusitis and allergy to fungal organisms. IgE levels were elevated in 8 of 9 patients, and 10 of 15 patients had eosinophilia. Surgical specimens demonstrated allergic mucin (n = 11), Charcot-Leyden crystals (n = 2), hyphae or fungal debris (n = 9), and fungal growth (n = 17). All patients underwent endoscopic sinus surgery, with 11 requiring multiple surgical procedures. Postoperatively, 19 patients received intranasal and oral steroids, and all had nasal saline washes. Eleven patients (9 who had undergone multiple surgical procedures) were treated with immunotherapy. Relapse was seen in 55% of patients at 1 year of follow-up. CONCLUSION: AFS presents with a higher incidence of proptosis in children when compared with adults. Typically, AFS occurs in atopic children with refractory sinus disease, requiring a high index of suspicion for evaluation and aggressive treatment.

The beta-agonist isoproterenol attenuates EGF-stimulated wound closure in human airway epithelial cells.

Asthma is a disease characterized by reversible airway obstruction. An additional hallmark of chronic asthma is altered wound healing that leads to airway remodeling. Although beta-agonists are effective in treating the bronchospasm associated with asthma, their effects on airway wound healing, which are related to airway remodeling, are unknown. It has been demonstrated that beta-agonists can alter the signaling of epidermal growth factor (EGF) receptors, which are important in timely wound healing. Therefore, we hypothesized that the beta-agonist isoproterenol would affect wound healing. Using an in vitro scrape wound assay, we demonstrated that isoproterenol attenuates EGF-stimulated wound healing in 16HBE airway epithelial cell cultures. Through experiments with forskolin and cells overexpressing beta2-adrenergic receptor-yellow fluorescent protein, we show that attenuation is due to the accumulation of cAMP and the involvement of at least one additional pathway. Furthermore, attenuation is not due to a direct effect on the EGF receptor or to an alteration of the ERK/MAPK signaling cascade. Based on these results, we propose that isoproterenol may exert its effects through other MAPK signaling pathways (JNK and/or p38) or through parallel mechanisms. These results also demonstrate a problem of potential therapeutic relevance in which a commonly prescribed medication may alter wound healing and contribute to the remodeling of asthmatic airways.

Coordinating epidermal growth factor-induced motility promotes efficient wound closure.

Wound healing is a response to injury that is initiated to reconstruct damaged tissue. In skin, reepithelialization involves both epithelial cells and fibroblasts and contributes to the reformation of a barrier between the external environment and internal milieu. Growth factors including epidermal growth factor (EGF) play important roles in promoting this process. In the present studies we employed CV-1 fibroblasts in a tissue culture model of reepithelialization to develop strategies for optimizing wound closure stimulated by EGF. We found that EGF enhanced cell motility within 6-8 h of EGF treatment in serum-free medium but wounds failed to close within 24 h. However, if medium on these cultures was exchanged for medium containing serum, cells pretreated with EGF closed new scrape wounds more rapidly than did cells that were not pretreated. These results indicate that serum factors work in concert with EGF to coordinate cell motility for efficient wound closure. Indeed, EGF enhanced the rate of wound closure in the presence of serum, and this effect also persisted for at least 24 h after EGF was removed. This coordination of EGF-induced cell motility was accompanied by an increase in the transient phosphorylation of ERK1 and ERK2. The persistent effects of EGF were blocked by transient exposure to reversible inhibitors of transcription and translation, indicating that the expression of new proteins mediated this response. We propose that EGF-stimulated CV-1 fibroblast motility is coordinated by a serum component that induces cell-cell adhesive properties consistent with an epithelial phenotype, thereby enhancing the reepithelialization process.

Characteristics of children with asthma who are enrolled in a Head Start program.

BACKGROUND: Asthma is an increasing public health concern that disproportionally affects children. In 1998, the Centers for Disease Control identified children aged 0 to 4 years as the "driving force" behind climbing rates of asthma-related emergency department visits and hospitalizations. Despite the significant asthma burden in preschool children, few studies characterize this population. OBJECTIVE: This study identifies and characterizes children at risk for asthma who are enrolled in a local Head Start program. METHODS: Caregivers of 368 children aged 3 to 5 years who were identified by using an asthma survey were recruited. Data were collected on demographics, health care use and access, medication use, symptoms, and trigger exposure. Exposure to tobacco smoke was determined by urinary cotinine and allergen sensitization by skin prick test. RESULTS: At baseline, 64% of the children had more than 1 emergency department visit for asthma in their lifetime, whereas 31% had more than 1 visit in the previous 6 months. Caretakers reported smoking in 37% of households with cotinine exceeding 20 ng/mg in 27% of the sample. Twenty-one percent reported symptoms consistent with intermittent asthma, and 79% reported symptoms consistent with persistent asthma. Forty-five percent of the children reported nighttime symptoms more than 1 night per week. Seventy-one percent had positive test results for more than 1 allergen, and 42% had positive test results for more than 3 allergens. Only 32% of children with persistent asthma had both rescue and controller medications. CONCLUSION: Children with asthma enrolled in a Head Start program have significant environmental tobacco smoke exposure, are highly atopic and symptomatic, and do not receive appropriate medication treatment. Overall, children in the study had poor asthma control. This high-risk group could benefit from case management programs.

Enhanced beta2-adrenergic receptor (beta2AR) signaling by adeno-associated viral (AAV)-mediated gene transfer.

BACKGROUND: Beta2-adrenergic receptors (beta2AR) play important regulatory roles in a variety of cells and organ systems and are important therapeutic targets in the treatment of airway and cardiovascular disease. Prolonged use of beta-agonists results in tolerance secondary to receptor down-regulation resulting in reduced therapeutic efficiency. The purpose of this work is to evaluate the signaling capabilities of the beta2AR expressed by a recombinant adeno-associated viral (AAV) vector that also included an enhanced green fluorescent protein (EGFP) gene (AAV-beta2AR/EGFP). RESULTS: By epifluorescence microscopy, approximately 40% of infected HEK 293 cells demonstrated EGFP expression. beta2AR density measured with [3H]dihydroalprenolol ([3H]DHA) increased either 13- or 77-fold in infected cells compared to mock infected controls depending on the culture conditions used. The [3H]DHA binding was to a single receptor population with a dissociation constant of 0.42 nM, as would be expected for wild-type beta2AR. Agonist competition assays with [3H]DHA showed the following rank order of potency: isoproterenol>epinephrine> norepinephrine, consistent with beta2AR interaction. Isoproterenol-stimulated cyclic AMP levels were 5-fold higher in infected cells compared to controls (314 +/- 43 vs. 63.4 +/- 9.6 nmol/dish; n = 3). Receptor trafficking demonstrated surface expression of beta2AR with vehicle treatment and internalization following isoproterenol treatment. CONCLUSIONS: We conclude that HEK 293 cells infected with AAV-beta2AR/EGFP effectively express beta2AR and that increased expression of these receptors results in enhanced beta2AR signaling. This method of gene transfer may provide an important means to enhance function in in vivo systems.

Molecular cloning and functional characterization of a vasotocin receptor subtype expressed in the pituitary gland of the domestic chicken (Gallus domesticus): avian homolog of the mammalian V1b-vasopressin receptor.

The neurohypophysial hormone arginine vasotocin (AVT) stimulates adrenocorticotropin hormone (ACTH) secretion from the avian anterior pituitary gland resulting in increased adrenal secretion of corticosterone in response to stress. Here, we report molecular cloning and functional characterization of a gene encoding an AVT receptor subtype, designated the VT2 receptor, that may mediate the stimulatory effect of AVT on ACTH secretion in birds. The open reading frame predicts a 425 amino acid polypeptide that includes seven segments of 19 to 24 hydrophobic amino acids, typical of guanine nucleotide-protein coupled receptors. Phylogenetic analysis revealed that the VT2 receptor shares highest identity with the mammalian V1b-vasopressin receptor subtype. Expressed VT2 receptors in COS7 cells mediate AVT-induced phosphatidylinositol turnover and Ca(2+) mobilization. In the domestic chicken, expression of VT2 receptor gene transcripts is limited to the pituitary gland. Based on similarities in sequence, site of expression and coupled signal transduction pathways, we conclude that the VT2 receptor is the avian homolog of the mammalian V1b-vasopressin receptor, and therefore may play an important role in the avian stress response.

EGF receptor downregulation depends on a trafficking motif in the distal tyrosine kinase domain.

On binding to its receptor, epidermal growth factor (EGF) initiates a cascade of events leading to cell proliferation or differentiation. In addition, the EGF receptor itself is downregulated to attenuate mitogenic signaling. Downregulation occurs through trafficking of receptors to lysosomes, culminating in proteolytic destruction of both the receptor and ligand; however, endocytic sorting mechanisms that underlie lysosomal targeting remain obscure. The goal of this study was to explore one aspect of the molecular basis for ligand-induced lysosomal targeting and degradation of EGF receptors. In this study, we identify a tyrosine-leucine motif ((954)YLVI) that is essential for transit of ligand-receptor complexes to lysosomes. When this motif is mutated, HEK 293 cells expressing the mutant receptors demonstrate impaired lysosomal targeting and downregulation compared with wild-type receptors. (954)YLVI is highly conserved among EGF receptors from various mammalian and invertebrate species and is critical for receptor downregulation. We propose that (954)YLVI works in concert with at least two additional regions within the EGF receptor cytoplasmic domain that are essential for efficiently targeting ligand-receptor complexes to the lysosome.