Characterizing human postprandial metabolic response using multiway data analysis.

INTRODUCTION: Analysis of time-resolved postprandial metabolomics data can improve our understanding of the human metabolism by revealing similarities and differences in postprandial responses of individuals. Traditional data analysis methods often rely on data summaries or univariate approaches focusing on one metabolite at a time. OBJECTIVES: Our goal is to provide a comprehensive picture in terms of the changes in the human metabolism in response to a meal challenge test, by revealing static and dynamic markers of phenotypes, i.e., subject stratifications, related clusters of metabolites, and their temporal profiles. METHODS: We analyze Nuclear Magnetic Resonance (NMR) spectroscopy measurements of plasma samples collected during a meal challenge test from 299 individuals from the COPSAC2000 cohort using a Nightingale NMR panel at the fasting and postprandial states (15, 30, 60, 90, 120, 150, 240 min). We investigate the postprandial dynamics of the metabolism as reflected in the dynamic behaviour of the measured metabolites. The data is arranged as a three-way array: subjects by metabolites by time. We analyze the fasting state data to reveal static patterns of subject group differences using principal component analysis (PCA), and fasting state-corrected postprandial data using the CANDECOMP/PARAFAC (CP) tensor factorization to reveal dynamic markers of group differences. RESULTS: Our analysis reveals dynamic markers consisting of certain metabolite groups and their temporal profiles showing differences among males according to their body mass index (BMI) in response to the meal challenge. We also show that certain lipoproteins relate to the group difference differently in the fasting vs. dynamic state. Furthermore, while similar dynamic patterns are observed in males and females, the BMI-related group difference is observed only in males in the dynamic state. CONCLUSION: The CP model is an effective approach to analyze time-resolved postprandial metabolomics data, and provides a compact but a comprehensive summary of the postprandial data revealing replicable and interpretable dynamic markers crucial to advance our understanding of changes in the metabolism in response to a meal challenge.

Fish oil supplementation during pregnancy, anthropometrics, and metabolic health at age ten: A randomized clinical trial.

BACKGROUND: We previously reported that children of mothers who received fish oil supplementation during pregnancy had higher body mass index [BMI (in kg/m2)] at 6 y of age as well as a concomitant increase in fat-, muscle, and bone mass, but no difference in fat percentage. OBJECTIVES: Here, we report follow-up at age 10 y including assessment of metabolic health. METHODS: This is a follow-up analysis of a randomized clinical trial conducted among 736 pregnant females and their offspring participating in the Copenhagen Prospective Studies on Asthma in Childhood mother-child cohort. The intervention was 2.4 g n-3 (ω-3) Long-Chain PolyUnsaturated Fatty Acid (n-3 LCPUFA) or control daily from pregnancy week 24 until 1 wk after birth. Outcomes were anthropometric measurements, body composition from Bioelectrical Impedance Analysis, blood pressure, concentrations of triglycerides, cholesterol, glucose, and C-peptide from fasting blood samples, and a metabolic syndrome score was calculated. Anthropometric measurements and body composition were prespecified secondary endpoints of the n-3 LCPUFA trial, and others were exploratory. RESULTS: Children in the n-3 LCPUFA group had a higher mean BMI at age 10 year compared to the control group: 17.4 (SD: 2.44) compared with 16.9 (2.28); P = 0.020 and a higher odds ratio of having overweight (odds ratio: 1.53; 95% CI: 1.01, 2.33; P = 0.047). This corresponded to differences in body composition in terms of increased lean mass (0.49 kg; 95% CI: -0.20, 1.14; P = 0.17), fat mass (0.49 kg; 95% CI: -0.03, 1.01; P = 0.06), and fat percent (0.74%; 95% CI: -0.01, 1.49; P = 0.053) compared to the control group. Children in the n-3 LCPUFA group had a higher metabolic syndrome score compared to the control (mean difference: 0.19; 95% CI: -0.02, 0.39; P = 0.053). CONCLUSIONS: In this randomized clinical trial, children of mothers receiving n-3 LCPUFA supplementation had increased BMI at age 10 y, increased risk of being overweight, and a tendency of increased fat percentage and higher metabolic syndrome score. These findings suggest potential adverse health effects from n-3 LCPUFA supplementation during pregnancy and need to be replicated in future independent studies. This trial was registered at clinicaltrials.gov as NCT00798226.

BURDEN AND SUBTYPES OF EARLY-LIFE INFECTIONS INCREASE THE RISK OF ASTHMA.

BACKGROUND: Early-life respiratory tract infections have been linked to the development of asthma, but studies on burden and subtypes of common infections in asthma development are sparse. OBJECTIVE: The study aimed to examine the association between burden of early-life infections, including subtypes, with risk of asthma from ages 3-10 years and lung function at age 10 years. METHODS: We included 662 children from the COPSAC2010 birth cohort, where infections, i.e., colds, acute tonsillitis, acute otitis media (AOM), pneumonia, gastroenteritis, and fever were registered prospectively in daily diaries at age 0-3 years, and asthma was diagnosed longitudinally from ages 3-10 years. The association between infection burden and subtypes and risk of asthma was analysed by generalized estimating equations. RESULTS: The children experienced a median of 16 [IQR=12-23] infections age 0-3 years. Children with a high burden of infections (above median) had an increased risk of asthma age 3-10: aOR=3.61 (2.39-5.45), p<0.001, which was driven by colds, pneumonia, gastroenteritis, and fever episodes (p-values<0.05), but not by AOM and tonsillitis. Lower lung function measures age 10 were associated with burden of pneumonia, but not the overall infection burden. The association between colds and risk of asthma was significantly higher in children with allergic rhinitis at age 6 (p-interaction=0.032). CONCLUSION: High burden of early-life infections in terms of colds, pneumonia, gastroenteritis, and fever is associated with increased risk of developing asthma, particularly in children with respiratory allergy. Strategies to diminish these early-life infections could potentially offer a path for primary prevention of childhood asthma.

An Unhealthy Dietary Pattern during Pregnancy is Associated with Neurodevelopmental Disorders in Childhood and Adolescence.

Despite the high prevalence of neurodevelopmental disorders, there are a lack of clinical studies examining the impact of pregnancy diet on child neurodevelopment. This observational clinical study examined the associations between pregnancy dietary patterns and neurodevelopmental diagnoses, as well as their symptoms, in a prospective cohort of 10-year-old children (n=508). Data-driven dietary patterns were derived from self-reported food frequency questionnaires. An Unhealthy dietary pattern in pregnancy (per SD change) was significantly associated with attention deficit hyperactivity disorder (ADHD) OR 1.66 [1.21 - 2.27], p=0.002 and autism diagnosis OR 2.22 [1.33 - 3.74], p=0.002 and associated symptoms p<0.001. Findings for ADHD were validated in two large (n=656, n=348), independent mother-child cohorts via blood metabolome modelling. Objective metabolite scores, assessed at five timepoints in mothers and children in two independent mother-child cohorts, indicated that the strongest association with ADHD was during early-to mid-pregnancy. These results provide evidence for targeted prenatal dietary interventions to prevent neurodevelopmental disorders in children.

Vertical Metabolome Transfer from Mother to Child: An Explainable Machine Learning Method for Detecting Metabolomic Heritability.

Vertical transmission of metabolic constituents from mother to child contributes to the manifestation of disease phenotypes in early life. This study probes the vertical transmission of metabolites from mothers to offspring by utilizing machine learning techniques to differentiate between true mother-child dyads and randomly paired non-dyads. Employing random forests (RF), light gradient boosting machine (LGBM), and logistic regression (Elasticnet) models, we analyzed metabolite concentration discrepancies in mother-child pairs, with maternal plasma sampled at 24 weeks of gestation and children's plasma at 6 months. The propensity of vertical transfer was quantified, reflecting the likelihood of accurate mother-child matching. Our findings were substantiated against an external test set and further verified through statistical tests, while the models were explained using permutation importance and SHapley Additive exPlanations (SHAP). The best model was achieved using RF, while xenobiotics were shown to be highly relevant in transfer. The study reaffirms the transmission of certain metabolites, such as perfluorooctanoic acid (PFOA), but also reveals additional insights into the maternal influence on the child's metabolome. We also discuss the multifaceted nature of vertical transfer. These machine learning-driven insights complement conventional epidemiological findings and offer a novel perspective on using machine learning as a methodology for understanding metabolic interactions.

Analyzing postprandial metabolomics data using multiway models: a simulation study.

BACKGROUND: Analysis of time-resolved postprandial metabolomics data can improve the understanding of metabolic mechanisms, potentially revealing biomarkers for early diagnosis of metabolic diseases and advancing precision nutrition and medicine. Postprandial metabolomics measurements at several time points from multiple subjects can be arranged as a subjects by metabolites by time points array. Traditional analysis methods are limited in terms of revealing subject groups, related metabolites, and temporal patterns simultaneously from such three-way data. RESULTS: We introduce an unsupervised multiway analysis approach based on the CANDECOMP/PARAFAC (CP) model for improved analysis of postprandial metabolomics data guided by a simulation study. Because of the lack of ground truth in real data, we generate simulated data using a comprehensive human metabolic model. This allows us to assess the performance of CP models in terms of revealing subject groups and underlying metabolic processes. We study three analysis approaches: analysis of fasting-state data using principal component analysis, T0-corrected data (i.e., data corrected by subtracting fasting-state data) using a CP model and full-dynamic (i.e., full postprandial) data using CP. Through extensive simulations, we demonstrate that CP models capture meaningful and stable patterns from simulated meal challenge data, revealing underlying mechanisms and differences between diseased versus healthy groups. CONCLUSIONS: Our experiments show that it is crucial to analyze both fasting-state and T0-corrected data for understanding metabolic differences among subject groups. Depending on the nature of the subject group structure, the best group separation may be achieved by CP models of T0-corrected or full-dynamic data. This study introduces an improved analysis approach for postprandial metabolomics data while also shedding light on the debate about correcting baseline values in longitudinal data analysis.

A systematic review and meta-analysis on absolute eosinophil counts and the risk of asthma in preschool children with wheezing: An EAACI Task Force Report.

Preschool children with wheezing disorders pose diagnostic and therapeutic challenges and consume substantial healthcare resources. Peripheral eosinophil blood count (EBC) has been proposed as a potential indicator for future asthma development. This review by the European Academy of Allergy and Clinical Immunology (EAACI) Preschool Wheeze Task Force aimed to provide systematic evidence for the association between increased EBC and the risk of future asthma, as well as to identify potential cutoff values. In February 2023, a search of PubMed, EMBASE, and Cochrane Library databases was conducted to identify studies comparing EBCs in preschool children with wheezing who continued to wheeze later in life and those who did not. Included observational studies focused on children aged <6 years with a wheezing disorder, assessment of their EBCs, and subsequent asthma status. No language or publication date restrictions were applied. Among the initial 3394 studies screened, 10 were included in the final analysis, involving 1225 patients. The data from these studies demonstrated that high EBC in preschool children with wheezing is associated with future asthma development, with odds ratios of 1.90 (95% CI: 0.45-7.98, p = .38), 2.87 (95% CI: 1.38-5.95, p < .05), and 3.38 (95% CI: 1.72-6.64, p < .05) for cutoff values in the <300, 300-449, and ≥450 cells/µL ranges, respectively. Defining a specific cutoff point for an elevated EBC lacks consistency, but children with EBC >300 cells/µL are at increased risk of asthma. However, further research is needed due to the limitations of the included studies. Future investigations are necessary to fully elucidate the discussed association.

Vitamin D Primary Prevention of Respiratory Infections and Asthma in Early Childhood: Evidence and Mechanisms.

Respiratory infections are a leading cause of child morbidity worldwide, and asthma is the most common chronic disorder in childhood. Both conditions associate with high socioeconomic costs and are major reasons for medication prescriptions and hospitalizations in children. Vitamin D deficiency has concomitantly increased with asthma prevalence and is hypothesized to play a key role in the development. Current evidence suggests that high prenatal and early childhood vitamin D could be protective against respiratory infections and asthma in some studies where several mechanisms are proposed. However, other studies have reported no effects on these outcomes. Therefore, future large intervention studies on this topic are warranted. Mechanistic studies have shown that vitamin D holds antimicrobial properties by inducing production of several peptides through altered gene expression. Others have shown a complex interplay between asthma risk genotypes, the sphingolipid pathway, and prenatal vitamin D in early childhood asthma. Vitamin D has also been suggested to change both airway immune and microbiota profiles, which are directly related to asthma risk. Finally, systemic low-grade inflammation seems to be regulated by vitamin D exposure. This review presents the current literature of the primary preventive effect of vitamin D on early childhood asthma and respiratory infections. Mechanisms of actions are discussed, and gaps in knowledge are highlighted to facilitate planning of future intervention trials.

Maternal Diet Associates with Offspring Bone Mineralization, Fracture Risk and Enamel Defects in Childhood and Influences the Prenatal Effect of High-Dose Vitamin D Supplementation.

We previously demonstrated a beneficial effect of high-dose vitamin D in pregnancy on offspring bone and dental health. Here, we investigated the effect of maternal dietary patterns during pregnancy on the risk of bone fractures, bone mineralization and enamel defects until age 6 years in the offspring. Further, the influence of diet on the effect of high-dose vitamin D was analyzed in the COPSAC2010 mother-child cohort including 623 mother-child pairs. A weighted network analysis on FFQs revealed three specific maternal dietary patterns that associated (Bonferroni p < 0.05) with both offspring bone and dental health. The effect of prenatal high-dose (2800 IU/day) vs. standard-dose (400 IU/day) vitamin D on offspring bone mineral content (adjusted mean difference (aMD): 33.29 g, 95% CI: 14.48-52.09, p < 0.001), bone mineral density (aMD: 0.02 g/cm2 (0.01-0.04), p < 0.001), fracture risk (adjusted incidence rate ratio: 0.36 (0.16-0.84), p = 0.02), and enamel defects in primary (adjusted odds ratio (aOR): 0.13 (0.03-0.58), p < 0.01) and permanent molars (aOR: 0.25; (0.10-0.63), p < 0.01) was most pronounced when mothers had lower intake of fruit, vegetables, meat, eggs, sweets, whole grain, offal and fish. This study suggests that prenatal dietary patterns influence offspring bone and dental development, and should be considered in order to obtain the full benefits of vitamin D to enhance personalized supplementation strategy.

Normal saline for children with bronchiolitis: study protocol for a randomised controlled non-inferiority trial.

INTRODUCTION: Bronchiolitis is one of the most common reasons for hospital admissions in early childhood. As supportive treatment, some treatment guidelines suggest using nasal irrigation with normal saline (NS) to facilitate clearance of mucus from the airways. In addition, most paediatric departments in Denmark use nebulised NS for the same purpose, which can mainly be administered as inpatient care. However, no studies have ever directly tested the effect of saline in children with bronchiolitis. METHODS AND ANALYSIS: The study is an investigator-initiated, multicentre, open-label, randomised, controlled non-inferiority trial and will be performed at six paediatric departments in eastern Denmark. We plan to include 300 children aged 0-12 months admitted to hospital with bronchiolitis. Participating children are randomised 1:1:1 to nebulised NS, nasal irrigation with NS or no saline therapy. All other treatment will be given according to standard guidelines.The primary outcome is duration of hospitalisation, analysed according to intention-to-treat analysis using linear regression and Cox regression analysis. By including at least 249 children, we can prove non-inferiority with a limit of 12 hours admission, alpha 2.5% and a power of 80%. Secondary outcomes are need for respiratory support with nasal continuous positive airway pressure or high-flow oxygen therapy and requirement of fluid supplements (either by nasogastric tube or intravenous). ETHICS AND DISSEMINATION: This study may inform current practice for supportive treatment of children with bronchiolitis. First, if NS is found to be helpful, it may be implemented into global guidelines. If no effect of NS is found, we can stop spending resources on an ineffective treatment. Second, if NS is effective, but nasal irrigation is non-inferior to nebulisation, it may reduce the workload of nurses, and possible duration of hospitalisation because the treatment can be delivered by the parents at home. TRIAL REGISTRATION NUMBER: NCT05902702.

High-dose vitamin D3 supplementation in pregnancy and risk of neurodevelopmental disorders in the children at age 10: A randomized clinical trial.

BACKGROUND: Vitamin D deficiency in pregnancy may increase the risk of autism and attention deficit hyperactivity disorder (ADHD). OBJECTIVE: The objective of this study was to estimate the effect of vitamin D3 supplementation in pregnancy on risk of autism and ADHD. DESIGN: This randomized clinical trial was part of the COpenhagen Prospective Study on Neuro-PSYCHiatric Development (COPYCH) project nested within the Copenhagen Prospective Studies on Asthma in Childhood 2010 (COPSAC2010) cohort comprising a population-based sample of 700 healthy mother-child pairs enrolled at week 24 of pregnancy. Maternal 25-hydroxy-vitamin D (25(OH)D) was measured at inclusion and 623 mothers were randomized 1:1 to either high-dose (2800 IU/d) or standard dose (400 IU/d) vitamin D3 until 1 wk postpartum (315 received high-dose, 308 standard dose). At age 10, diagnoses and symptom load of autism and ADHD, respectively, were established using the Kiddie-Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version. RESULTS: The psychopathologic evaluation was completed by 591 children aged 10 y, and 16 children (2.7%) were diagnosed with autism and 65 (11.0%) with ADHD. Hereof, 496 children participated in the vitamin D3 trial (246 received high-dose, 250 standard dose). Of these, 12 children (2.4%) were diagnosed with autism and 58 (11.7%) with ADHD. Higher maternal preintervention 25(OH)D levels were associated with a decreased risk of autism [odd ratio (OR) per 10 nmol/L: 0.76 (0.59,0.97); P = 0.034], lower autistic symptom load [ß per 10 nmol/L: -0.03 (-0.05,0.00); P = 0.024), and decreased risk of ADHD diagnosis (OR per 10 nmol/L: 0.88 (0.78,0.99); P = 0.033]. High-dose vitamin D3 supplementation was not associated with risk of autism or ADHD. CONCLUSIONS: Higher maternal preintervention 25(OH)D was associated with a decreased risk of autism, lower autistic symptom load, and decreased risk of ADHD diagnosis, but high-dose vitamin D3 supplementation in pregnancy had no effect on risk of autism and ADHD. This trial was registered at clinicaltrials.gov as NCT00856947.

Sphingolipid classes and the interrelationship with pediatric asthma and asthma risk factors.

BACKGROUND: While dysregulated sphingolipid metabolism has been associated with risk of childhood asthma, the specific sphingolipid classes and/or mechanisms driving this relationship remain unclear. We aimed to understand the multifaceted role between sphingolipids and other established asthma risk factors that complicate this relationship. METHODS: We performed targeted LC-MS/MS-based quantification of 77 sphingolipids in plasma from 997 children aged 6 years from two independent cohorts (VDAART and COPSAC2010 ). We examined associations of circulatory sphingolipids with childhood asthma, lung function, and three asthma risk factors: functional SNPs in ORMDL3, low vitamin D levels, and reduced gut microbial maturity. Given racial differences between these cohorts, association analyses were performed separately and then meta-analyzed together. RESULTS: We observed elevations in circulatory sphingolipids with asthma phenotypes and risk factors; however, there were differential associations of sphingolipid classes with clinical outcomes and/or risk factors. While elevations from metabolites involved in ceramide recycling and catabolic pathways were associated with asthma and worse lung function [meta p-value range: 1.863E-04 to 2.24E-3], increased ceramide levels were associated with asthma risk factors [meta p-value range: 7.75E-5 to .013], but not asthma. Further investigation identified that some ceramides acted as mediators while some interacted with risk factors in the associations with asthma outcomes. CONCLUSION: This study demonstrates the differential role that sphingolipid subclasses may play in asthma and its risk factors. While overall elevations in sphingolipids appeared to be deleterious overall; elevations in ceramides were uniquely associated with increases in asthma risk factors only; while elevations in asthma phenotypes were associated with recycling sphingolipids. Modification of asthma risk factors may play an important role in regulating sphingolipid homeostasis via ceramides to affect asthma. Further function work may validate the observed associations.

Key risk factors of asthma-like symptoms are mediated through infection burden in early childhood.

BACKGROUND: Risk factors of asthma-like symptoms in childhood may act through an increased infection burden because infections often trigger these symptoms. OBJECTIVE: We sought to investigate whether the effect of established risk factors of asthma-like episodes in early childhood is mediated through burden and subtypes of common infections. METHODS: The study included 662 children from the Copenhagen Prospective Studies on Asthma in Childhood 2010 mother-child cohort, in which infections were registered prospectively in daily diaries from age 0 to 3 years. The association between established risk factors of asthma-like episodes and infection burden was analyzed by quasi-Poisson regressions, and mediation analyses were performed for significant risk factors. RESULTS: In the first 3 years of life, the children experienced a median of 16 (interquartile range, 12-23) infectious episodes. We found that the infection burden significantly (PACME < .05) mediated the association of maternal asthma (36.6% mediated), antibiotics during pregnancy (47.3%), siblings at birth (57.7%), an asthma exacerbation polygenic risk score (30.6%), and a bacterial airway immune score (80.2%) with number of asthma-like episodes, whereas the higher number of episodes from male sex, low birth weight, low gestational age, and maternal antibiotic use after birth was not mediated through an increased infection burden. Subtypes of infections driving the mediation were primarily colds, pneumonia, gastroenteritis, and fever, but not acute otitis media or acute tonsillitis. CONCLUSIONS: Several risk factors of asthma-like symptoms in early childhood act through an increased infection burden in the first 3 years of life. Prevention of infectious episodes may therefore be beneficial to reduce the burden of asthma-like symptoms in early childhood.

Maternal inflammation during pregnancy is associated with risk of ADHD in children at age 10.

INTRODUCTION: Maternal inflammation during pregnancy may affect early neurodevelopment in offspring as suggested by preclinical and register data. However, clinical evidence for risk of aberrant neurodevelopment later in childhood is scarce. In the population-based COPSAC2010 mother-child cohort, we investigated associations between maternal inflammation levels during pregnancy and the risk of a diagnosis of ADHD as well as the load of ADHD symptoms in the children at age 10. METHODS: The COPSAC2010 cohort consists of 700 mother-child pairs followed prospectively since pregnancy week 24.Maternal high-sensitivity C-Reactive Protein (hs-CRP) level at week 24 of gestation was investigated in relation to child neurodevelopment by age 10 using logistic and linear regression models with extensive confounder adjustment, including socioeconomic status and maternal polygenic risk of ADHD. The children completed a comprehensive examination of neurodevelopment including categorical (i.e., diagnostic) and dimensional (i.e., symptom load) psychopathology using the Kiddie Schedule for Affective Disorders and Schizophrenia Present and Lifetime Version (K-SADS-PL) and parental rated ADHD-Rating Scale (ADHD-RS). RESULTS: A total of 604 (86 %) of the 700 children in the COPSAC2010 cohort participated in the COPSYCH visit at age 10. Sixty-five (10.8 %) fulfilled a research diagnosis of ADHD (16 girls and 49 boys). Higher maternal hs-CRP level in pregnancy at week 24 (median 5.4 mg/L) was significantly associated with increased risk for a diagnosis of ADHD, adjusted OR 1.40, 95 %CI (1.16-1.70), p = 0.001. Additionally, higher maternal hs-CRP was associated with increased ADHD symptom load in the entire cohort, reflected by ADHD-RS raw scores. DISCUSSION: These clinical data demonstrated a robust association of prenatal maternal inflammation assessed by hs-CRP with a diagnosis of ADHD by age 10. Moreover, maternal inflammation was associated with ADHD symptom load in the complete cohort. Identifying inflammation as an important marker will provide a potential target for future increased awareness and prevention during pregnancy thereby ultimately improving neurodevelopmental outcomes in children.

Bacterial colonisation of the airway in neonates and risk of asthma and allergy until age 18†years.

BACKGROUND: We previously showed an association between neonatal bacterial airway colonisation and increased risk of persistent wheeze/asthma until age 5 years. Here, we study the association with persistent wheeze/asthma and allergy-related traits until age 18 years. METHODS: We investigated the association between airway colonisation with Streptococcus pneumoniae, Moraxella catarrhalis and/or Haemophilus influenzae in 1-month-old neonates from the COPSAC2000 mother-child cohort and the development of persistent wheeze/asthma and allergy-related traits longitudinally until age 18 years using generalised estimating equations. Replication was sought in the similarly designed COPSAC2010 cohort of 700 children. RESULTS: Neonatal airway colonisation was present in 66 (21%) out of 319 children and was associated with a 4-fold increased risk of persistent wheeze/asthma (adjusted OR 4.01 (95% CI 1.76-9.12); p<0.001) until age 7 years, but not from age 7 to 18 years. Replication in the COPSAC2010 cohort showed similar results using 16S data. Colonisation was associated with an increased number of exacerbations (adjusted incidence rate ratio 3.20 (95% CI 1.38-7.44); p<0.01) until age 7 years, but not from age 7 to 18 years. Colonisation was associated with increased levels of blood eosinophils (adjusted geometric mean ratio 1.24 (95% CI 1.06-1.44); p<0.01) and tumour necrosis factor (TNF)-α (adjusted geometric mean ratio 1.09 (95% CI 1.02-1.16); p=0.01) until age 12 years. There were no associations with lung function, bronchial reactivity, fractional exhaled nitric oxide, allergic sensitisation, total IgE or atopic dermatitis up to age 18 years. CONCLUSIONS: Neonatal airway colonisation was associated with early-onset persistent wheeze/asthma, exacerbations, elevated blood eosinophils and elevated TNF-α in blood, most prominent in early childhood, thereafter diminishing and no longer evident by age 18 years.

The infant gut virome is associated with preschool asthma risk independently of bacteria.

Bacteriophage (also known as phage) communities that inhabit the gut have a major effect on the structure and functioning of bacterial populations, but their roles and association with health and disease in early life remain unknown. Here, we analyze the gut virome of 647 children aged 1 year from the Copenhagen Prospective Studies on Asthma in Childhood2010 (COPSAC2010) mother-child cohort, all deeply phenotyped from birth and with longitudinally assessed asthma diagnoses. Specific temperate gut phage taxa were found to be associated with later development of asthma. In particular, the joint abundances of 19 caudoviral families were found to significantly contribute to this association. Combining the asthma-associated virome and bacteriome signatures had additive effects on asthma risk, implying an independent virome-asthma association. Moreover, the virome-associated asthma risk was modulated by the host TLR9 rs187084 gene variant, suggesting a direct interaction between phages and the host immune system. Further studies will elucidate whether phages, alongside bacteria and host genetics, can be used as preclinical biomarkers for asthma.

Exhaled nitric oxide is only an asthma-relevant biomarker among children with allergic sensitization.

BACKGROUND: Fraction of exhaled nitric oxide (FeNO) is used for diagnosing and monitoring asthma in children, but the influence of allergic sensitization is still poorly understood. Here, we investigate how asthma and allergic sensitization influence FeNO levels during childhood. METHODS: We investigated the associations between asthma, aeroallergen sensitization, and FeNO measured from age 5-18 years in the COPSAC2000 birth cohort of 411 children using repeated measurement mixed models adjusted for gestational age, sex, concurrent airway infection, inhaled corticosteroids, and tobacco exposure. Replication was sought in the similarly designed COPSAC2010 cohort of 700 children. RESULTS: In the COPSAC2000 cohort, 133 had asthma between age 5 and 18 years, and in the COPSAC2010 cohort, 112 had asthma between age 5 and 10 years. In the COPSAC2000 cohort, asthma and aeroallergen sensitization were both associated with higher FeNO from age 5 to 18 years: adjusted geometric mean ratio (aGMR), 1.22 (1.08-1.35), p < .01, and 1.41 (1.21-1.65), p < 0.001, respectively. However, asthma was associated with increased FeNO among children with aeroallergen sensitization: 1.44 (1.23-1.69), p < .0001, whereas asthma was associated with decreased FeNO among nonsensitized children: 0.80 (0.65-0.99), p = .05 (p-interaction<.0001 for asthma x sensitization). Replication in the COPSAC2010 cohort showed similar results (p-interaction <.01). Further, blood eosinophil count, total-IgE, bronchodilator response, and bronchial hyperreactivity were all associated with increased FeNO among children sensitized to aeroallergens, but not among nonsensitized children. CONCLUSION: Fraction of exhaled nitric oxide is elevated through childhood in children with asthma and is correlated with asthma-associated traits depending on the presence of aeroallergen sensitization. These findings indicate that FeNO is only a valid asthma biomarker in children with concurrent aeroallergen sensitization, which is important for guideline recommendations on the clinical use of FeNO.

Limited clinical role of blood eosinophil levels in early life atopic disease: A mother-child cohort study.

BACKGROUND: Blood eosinophil count is a well-established biomarker of atopic diseases in older children and adults. However, its predictive role for atopic diseases in preschool children is not well established. OBJECTIVE: To investigate the association between blood eosinophil count in children and development of atopic diseases up to age 6 years. METHODS: We investigated blood eosinophil count at age 18 months and 6 years in relation to recurrent wheeze/asthma, atopic dermatitis, allergic rhinitis, and allergic sensitization during the first 6 years of life in the two Copenhagen Prospective Studies on Asthma in Childhood cohorts (n = 1111). Blood eosinophil count was investigated in association with remission of existing atopic disease, current atopic disease, and later development of atopic disease. RESULTS: Blood eosinophil count at 18 months was not associated with current wheezing/asthma or atopic dermatitis, while blood eosinophil count at age 6 years was associated with increased occurrence of current wheezing/asthma (OR = 1.1; 1.04-1.16, p = .0005), atopic dermatitis (OR = 1.06; 1.01-1.1, p = .02), and allergic rhinitis (OR = 1.11; 1.05-1.18, p = .0002). Blood eosinophil count at 18 months did not predict persistence or development of recurrent wheeze/asthma or atopic dermatitis at age 6 years. CONCLUSION: Blood eosinophil count at 18 months was not associated with current wheezing/asthma or atopic dermatitis and did not predict persistence or development of disease. This implies a limited clinical role of blood eosinophil levels in early-life atopic disease and questions the clinical value of blood eosinophil counts measured in toddlers as a predictive biomarker for subsequent atopic disease in early childhood.