Fractional exhaled nitric oxide measurements are most closely associated with allergic sensitization in school-age children

Background: Factors affecting fractional exhaled nitric oxide (FeNO) in early childhood are incompletely understood. Objective: To examine the relationships between FeNO and allergic sensitization, total IgE, atopic dermatitis, rhinitis, asthma, and lung function (spirometry) in children. Methods: Children at high risk of asthma and other allergic diseases because of parental history were enrolled at birth and followed prospectively. FeNO was measured by an online technique at ages 6 and 8 years. Relationships among FeNO, various atopic characteristics, and asthma were evaluated. Results: Reproducible FeNO measurements were obtained in 64% (135/210) of 6-year-old and 93% (180/194) of 8-year-old children. There was seasonal variability in FeNO. Children with aeroallergen sensitization at ages 6 and 8 years had increased levels of FeNO compared with those not sensitized (geometric mean; 6 years, 10.9 vs 6.7 parts per billion [ppb], P < .0001; 8 years, 14.6 vs 7.1 ppb, P < .0001). FeNO was higher in children with asthma than in those without asthma at 8 years but not 6 years of age (6 years, 9.2 vs 8.3 ppb, P 5 .48; 8 years, 11.5 vs 9.2 ppb, P 5 .03). At 8 years of age, this difference was no longer significant in a multivariate model that included aeroallerge

Rhinovirus illnesses during infancy predict subsequent childhood wheezing

Background: The contribution of viral respiratory infections during infancy to the development of subsequent wheezing and/ or allergic diseases in early childhood is not established. Objective: To evaluate these relationships prospectively from birth to 3 years of age in 285 children genetically at high risk for developing allergic respiratory diseases. Methods: By using nasal lavage, the relationship of timing, severity, and etiology of viral respiratory infections during infancy to wheezing in the 3rd year of life was evaluated. In addition, genetic and environmental factors that could modify risk of infections and wheezing prevalence were analyzed. Results: Risk factors for 3rd year wheezing were passive smoke exposure (odds ratio [OR] 5 2.1), older siblings (OR 5 2.5), allergic sensitization to foods at age 1 year (OR 5 2.0), any moderate to severe respiratory illness without wheezing during infancy (OR 5 3.6), and at least 1 wheezing illness with respiratory syncytial virus (RSV; OR 5 3.0), rhinovirus (OR 5 10) and/or non-rhinovirus/RSV pathogens (OR 5 3.9) during infancy. When viral etiology was considered, 1st-year wheezing illnesses caused by rhinovirus infection were the strongest predictor of subsequent 3rd year wheezing (OR 5 6.6; P < .0001). Moreover, 63% of infants who wheezed during rhinovirus seasons continued to wheeze in the 3rd year of life, compared with only 20% of all other infants (OR 5 6.6; P < .0001). Conclusion: In this population of children at increased risk of developing allergies and asthma, the most significant risk factor for the development of preschool childhood wheezing is the occurrence of symptomatic rhinovirus illnesses during infancy that are clinically and prognostically informative based on their seasonal nature. (J Allergy Clin Immunol 2005;116:571-7.

Enhanced Neutralizing Antibody Responses to Rhinovirus C and Age-Dependent Patterns of Infection

Knowledge of prevalent RV types, antibody responses, and populations at risk based on age and genetics may guide the development of vaccines or other novel therapies against this important respiratory pathogen.Longitudinal data from the Childhood Origins of ASThma (COAST) birth cohort study were analyzed to determine relationships between age and RV-C infections. Neutralizing antibodies specific for rhinovirus A (RV-A) and RV-C (3 types each) were determined using a novel polymerase chain reaction-based assay. We pooled data from 14 study cohorts in the United States, Finland, and Australia and used mixed-effects logistic regression to identify factors related to the proportion of RV-C versus RV-A detection.In COAST, RV-A and RV-C infections were similarly common in infancy, while RV-C was detected much less often than RV-A during both respiratory illnesses and scheduled surveillance visits (pRhinovirus C (RV-C) can cause asymptomatic infection and respiratory illnesses ranging from the common cold to severe wheezing.To identify how age and other individual-level factors are associated with susceptibility to RV-C illnesses.</div

Cytokine response patterns, exposure to viruses, and respiratory infections in the first year of life

Keywords: interferon-␥; respiratory syncytial virus; daycare; sibling Viral respiratory illnesses, many of which are contracted through contact with siblings or attendance at daycare, are the most common triggers for wheezing and asthma exacerbations among young children. In both the Tucson Children&apos;s Respiratory Study (1, 2) and the Italian Studies of Respiratory Disorders in Childhood and the Environment project (3), daycare attendance was shown to be a risk factor for viral infections and viral-associated wheezing in the first 2 years of life, but protective against viral infections and asthma later in life. Celedon and colleagues found that daycare attendance during the first year of life was associated with lower rates of asthma at 6 years of age, but only among children without a maternal history of asthma (4). Similarly, children with older siblings in the home are more likely to experience viral illnesses and wheezing in the first 2 years of life, but have decreased rates of wheezing, and decreased rates of atopic sensitization later in childhood (2, 3, 5, 6). Despite the convincing evidence linking exposure to other children with rates of respiratory illnesses and wheezing, the effects of increased exposure on specific viral infections have not been ascertained. While exposure is an important determinant of lower respiratory tract illnesses, it does not explain why some children entering daycare experience a dramatic increase in viral infections, while others are relatively healthy. In addition, recent genetic studies suggest that clinical outcomes of viral infections in infancy might also be influenced by polymorphisms in cytokine genes (7-9). These observations suggest the hypotheses that variations and/or subtle defects in the antiviral immune response also affect the clinical expression of viral respiratory infections. Furthermore, stressing the immune system with increased viral exposure may uncover relatively minor immune defects that are not apparent in children with less exposure to viruses. To test these hypotheses, we conducted a prospective birth cohort study to evaluate interactions between exposure to other children, the development patterns of cytokine responses in peripheral blood cells, and the etiology and severity of respiratory viral infections during the first year of life. Other study results pertinent to this cohort have been previously published as both original articles and abstracts (10-13)

Genetic associations with viral respiratory illnesses and asthma control in children

BACKGROUND: Viral respiratory infections can cause acute wheezing illnesses in children and exacerbations of asthma. OBJECTIVE: We sought to identify variation in genes with known antiviral and pro-inflammatory functions to identify specific associations with more severe viral respiratory illnesses and the risk of virus-induced exacerbations during the peak fall season. METHODS: The associations between genetic variation at 326 SNPs in 63 candidate genes and 10 phenotypes related to viral respiratory infection and asthma control were examined in 226 children enrolled in the RhinoGen study. Replication of asthma control phenotypes was performed in 2,128 children in the Copenhagen Prospective Study on Asthma in Childhood (COPSAC). Significant associations in RhinoGen were further validated using virus-induced wheezing illness and asthma phenotypes in an independent sample of 122 children enrolled in the Childhood Origins of Asthma birth cohort study (COAST). RESULTS: A significant excess of P values smaller than 0.05 was observed in the analysis of the 10 RhinoGen phenotypes. Polymorphisms in 12 genes were significantly associated with variation in the four phenotypes showing a significant enrichment of small P values. Six of those genes (STAT4, JAK2, MX1, VDR, DDX58, and EIF2AK2) also showed significant associations with asthma exacerbations in the COPSAC study or with asthma or virus-induced wheezing phenotypes in the COAST study. CONCLUSIONS: We identified genetic factors contributing to individual differences in childhood viral respiratory illnesses and virus-induced exacerbations of asthma. Defining mechanisms of these associations may provide insight into the pathogenesis of viral respiratory infections and virus-induced exacerbations of asthma

Wheezing Rhinovirus Illnesses in Early Life Predict Asthma Development in High-Risk Children

Rationale: Virus-induced wheezing episodes in infancy often precede the development of asthma. Whether infections with specific viral pathogens confer differential future asthma risk is incompletely understood