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 2128 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 (COAST) birth cohort study.

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.

17q21 gene variation is not associated with asthma in adulthood

BACKGROUND

17q21 gene variants are the strongest known genetic determinants for childhood asthma and have been reported to interact with environmental tobacco smoke exposure in childhood. It remains unclear whether individuals with 17q21 risk variants have increased risk of asthma or reduced lung function in adulthood. The aim was to examine the association between the 17q21 region and current adult asthma and lung function, and interaction with active smoking.

METHODS

We investigated the single nucleotide polymorphism rs7216389 at the 17q21 locus in 3471 adults from the Health2006 cross-sectional study and in 7008 adults from The British 1958 Birth Cohort and examined the association with current asthma, spirometry measures, and related atopic traits. Analyses were performed for interaction with active smoking.

RESULTS

We found no association between rs7216389[T] and asthma when meta-analyzed (OR = 1.02 [0.92-1.13], P = 0.81). The risk variant was associated with reduced FEV1 as compared to normal FEV1 (OR = 1.10 [1.01-1.12], P = 0.033) and with allergic sensitization (OR = 1.10 [1.03-1.17], P = 0.003). Individuals with rs7216389 risk variants smoked as frequently as individuals without risk variants, and there was no evidence that smoking modified the association between rs7216389 and asthma.

CONCLUSION

Our study suggests that the 17q21 rs7216389 locus variant does not substantially influence asthma risk in adulthood or susceptibility to detrimental effects of active smoking. This contrasts the findings in children and suggests that this locus is associated with a childhood-specific asthma endotype.

Deep phenotyping of the unselected COPSAC2010 birth cohort study

Background

We hypothesize that perinatal exposures, in particular the human microbiome and maternal nutrition during pregnancy, interact with the genetic predisposition to cause an abnormal immune modulation in early life towards a trajectory to chronic inflammatory diseases such as asthma and others.

Objective

The aim of this study is to explore these interactions by conducting a longitudinal study in an unselected cohort of pregnant women and their offspring with emphasis on deep clinical phenotyping, exposure assessment, and biobanking. Exposure assessments focus on the human microbiome. Nutritional intervention during pregnancy in randomized controlled trials are included in the study to prevent disease and to be able to establish causal relationships.

Methods

Pregnant women from eastern Denmark were invited during 2008–2010 to a novel unselected ‘COPSAC₂₀₁₀’ cohort. The women visited the clinic during pregnancy weeks 24 and 36. Their children were followed at the clinic with deep phenotyping and collection of biological samples at nine regular visits until the age of 3 and at acute symptoms. Randomized controlled trials of high‐dose vitamin D and fish oil supplements were conducted during pregnancy, and a trial of azithromycin for acute lung symptoms was conducted in the children with recurrent wheeze.

Results

Seven hundred and thirty‐eight mothers were recruited from week 24 of gestation, and 700 of their children were included in the birth cohort. The cohort has an over‐representation of atopic parents. The participant satisfaction was high and the adherence equally high with 685 children (98%) attending the 1 year clinic visit and 667 children (95%) attending the 2 year clinic visit.

Conclusions

The COPSAC₂₀₁₀ birth cohort study provides longitudinal clinical follow‐up with highly specific end‐points, exposure assessments, and biobanking. The cohort has a high adherence rate promising strong data to elucidate the interaction between genomics and the exposome in perinatal life leading to lifestyle‐related chronic inflammatory disorders such as asthma.

Systemic exposure to inhaled beclometasone/formoterol DPI is age and body size dependent

AIM

Prescription of inhaled corticosteroids to children with asthma is recommended at half the nominal dose of adults in order to reduce the risk of systemic side effects. However, there is a lack of pharmacokinetic trials supporting such dose reduction regimens. Therefore, we aimed to compare the systemic exposure to the active ingredients of a fixed dose combination of beclometasone-dipropionate (BDP) and formoterol after dry powder inhaler (DPI) administration in children, adolescents and adults.

METHODS

The pharmacokinetic profiles of formoterol and beclometasone-17-monopropionate (B17MP; active metabolite of BDP) were evaluated over 8 h from two independent studies comprising children (6-11yrs, n = 27), adolescents (12-17 yrs, n = 28) and adults (≥18 yrs, n = 30) receiving a single, fixed dose of BDP/formoterol (children: 200 μg/24 μg, adolescents and adults: 400 μg/24 μg) via DPI.

RESULTS

The systemic exposure (AUC) for children versus adults was almost doubled for formoterol and similar for B17MP despite the halved BDP dose administered in children. In adolescents the AUC for formoterol and B17MP were approximately one third higher than in adults for both compounds. Upon normalization for the BDP/formoterol dose in the three populations the AUC and peak concentration (C(max)) correlated inversely with age and body surface area of the patients (r ≤ -0.53; p < 0.0001).

CONCLUSION

The systemic exposure to the active ingredients of BDP/formoterol administered as DPI correlates inversely with age and body size suggesting that dry powder dosage regimens should be adjusted for age and body size to avoid high systemic drug levels in children.

VEGFA variants are associated with pre-school lung function, but not neonatal lung function

BACKGROUND

Vascular endothelial growth factor (VEGF) is implicated in airway remodelling and asthma development. We studied VEGFA gene variants and plasma levels and the development of lung function, bronchial hyperresponsiveness and asthma in childhood.

METHODS

We analysed 13 SNPs in the VEGFA gene in 411 children from the COPSAC2000 high-risk birth cohort. Asthma was diagnosed prospectively, and lung function measurements were obtained at birth and 6 years of age. Plasma VEGF levels were measured at 18 months of age. We used a Bonferroni adjusted significance level. Findings were replicated in the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort at age 8.

RESULTS

At age six, three SNPs from the same linkage block were associated with FEV1 (rs699947, P = 1.31E-05), independent of asthma, and there were suggestive associations between FEV1/FVC ratio and rs833052 and maximal mid-expiratory flow and rs6900017. Replication in the PIAMA cohort showed borderline association between FEV1 and rs699947 and significant meta-analysis result. SNPs upstream and nearby rs699947 were nominally associated with VEGF plasma levels. VEGF levels were not associated with asthmatic symptoms or lung function measures.

CONCLUSIONS AND CLINICAL RELEVANCE

VEGF gene variants are associated with lung function at school age, but not at birth, suggesting a role of VEGF in post-natal lung function development.

Allergic rhinitis is associated with otitis media with effusion: a birth cohort study

BACKGROUND

Childhood otitis media with effusion is a common disease and a link to allergic diseases has been suggested.

OBJECTIVE

To investigate the association between atopic disease and otitis media with effusion diagnosed according to strict objective case definitions by age 6 years.

METHODS

We evaluated 291 children in the 6th year of life from the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) 2000 birth cohort. Otitis media with effusion was diagnosed based on tympanometric and objective evaluation. Asthma, eczema, allergic- and non-allergic rhinitis was diagnosed prospectively by pre-defined algorithms. Nasal mucosal swelling was assessed using acoustic rhinometry and nasal eosinophilia from scrapings. Analyses were performed using logistic regression and adjusted for dog, cat and smoking exposure, paternal atopy, household income, older siblings, gender and number of acute otitis media episodes.

RESULTS

Otitis media with effusion was diagnosed in 39% of the cohort and was associated with allergic rhinitis (aOR = 3.36, CI = 1.26-8.96, P = 0.02), but not with nasal mucosal swelling, nasal oeosinophilia, non-allergic rhinitis, asthma or eczema.

CONCLUSION

Otitis media with effusion is closely associated with allergic rhinitis presumably caused by allergic inflammation, but not mechanical nasal mucosal swelling. These findings warrant an increased awareness of otitis media with effusion in children with allergic rhinitis.