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.

Genetic predisposition to high BMI increases risk of early life respiratory infections and episodes of severe wheeze and asthma.

BACKGROUND: High BMI is an established risk factor for asthma, but the underlying mechanisms remain unclear.Objective: To increase understanding of the BMI-asthma relationship by studying the association between genetic predisposition to higher body mass index (BMI) and asthma, infections, and other asthma-traits during childhood. METHODS: Data was obtained from the two ongoing COPSAC mother-child cohorts. Polygenic risk score (PRS) for adult BMI were calculated for each child. Replication was done in the large-scale iPSYCH cohort using data on hospitalization for asthma and infections. RESULTS: In the COPSAC cohorts (n=974), the adult BMI PRS was significantly associated with lower respiratory tract infections (LRTI) (IRR 1.20 95% CI 1.08-1.33, FDR=0.005) age 0-3 years and episodes of severe wheeze (IRR 1.30, 1.06-1.60, FDR=0.04) age 0-6 years. LRTI partly mediated the association between the adult BMI PRS and severe wheeze (proportion mediated: 0.59, 0.28-2.24, pACME 2E-16). In contrast, these associations were not mediated through the child's current BMI and the PRS was not associated with an asthma diagnosis or reduced lung function up to age 18. The associations were replicated in iPSYCH (n=114 283), where the adult BMI PRS significantly increased the risk of hospitalizations for LRTI and wheeze or asthma during childhood to age 18 years. CONCLUSION: Children with genetic predisposition to higher BMI had increased risk of LRTI and severe wheeze, independent of the child's current BMI. These results shed further light on the complex relationship between BMI and asthma.

Infantile colic is associated with development of later constipation and atopic disorders.

BACKGROUND: Infantile colic is a common condition with limited knowledge about later clinical manifestations. We evaluated the role of the early life gut microbiome in infantile colic and later development of atopic and gastrointestinal disorders. METHODS: Copenhagen Prospective Studies on Asthma in Childhood2010 cohort was followed with 6 years of extensive clinical phenotyping. The 1-month gut microbiome was analyzed by 16S rRNA sequencing. Infantile colic was evaluated at age 3 months by interviews. Clinical endpoints included constipation to age 3 years and prospectively diagnosed asthma and atopic dermatitis in the first 6 years of life, and allergic sensitization from skin prick tests, specific Immunoglobulin E, and component analyses. RESULTS: Of 695 children, 55 children (7.9%) had infantile colic. Several factors were associated with colic including race, breastfeeding, and pets. The 1-month gut microbiome composition and taxa abundances were not associated with colic, however a sparse Partial Least Squares model including combined abundances of nine species was moderately predictive of colic: median, cross-validated AUC = 0.627, p = .003. Children with infantile colic had an increased risk of developing constipation (aOR, 2.88 [1.51-5.35], p = .001) later in life, but also asthma (aHR, 1.69 [1.02-2.79], p = .040), atopic dermatitis (aHR, 1.84 [1.20-2.81], p = .005) and had a higher number of positive allergic components (adjusted difference, 116% [14%-280%], p = .012) in the first 6 years. These associations were not mediated by gut microbiome differences. CONCLUSIONS: We link infantile colic with risk of developing constipation and atopic disorders in the first 6 years of life, which was not mediated through an altered gut microbiome at age 1-month. These results suggest infantile colic to involve gastrointestinal and/or atopic mechanisms.

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.

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 the burden and subtypes of common infections in asthma development are sparse. OBJECTIVE: To examine the association between burden of early life infections, including subtypes, with the risk of asthma from age 3 to 10 years and lung function at age 10 years. METHODS: We included 662 children from the Copenhagen Prospective Studies on Asthma in Childhood 2010 birth cohort, for whom infections such as colds, acute tonsillitis, acute otitis media, pneumonia, gastroenteritis, and fever were registered prospectively in daily diaries at age 0 to 3 years and asthma was diagnosed longitudinally from age 3 to 10 years. The association between the burden of infection and subtypes and risk of asthma was analyzed by generalized estimating equations. RESULTS: The children experienced a median of 16 infections (interquartile range, 12-23 infections) at age 0 to 3 years. Children with a high burden of infections (above the median) had an increased risk of asthma at age 3 to 10 years (adjusted odds ratio = 3.61; 95% CI, 2.39-5.45; P < .001), which was driven by colds, pneumonia, gastroenteritis, and fever episodes (P < .05) but not by acute otitis media and tonsillitis. Lower lung function measures at age 10 years were associated with the burden of pneumonia but not the overall infection burden. The association between colds and the risk of asthma was significantly higher in children with allergic rhinitis at age 6 years (P interaction = .032). CONCLUSION: A high burden of early life infections in terms of colds, pneumonia, gastroenteritis, and fever is associated with an increased risk of developing asthma, particularly in children with respiratory allergy. Strategies to diminish these early life infections may offer a path for the primary prevention of childhood asthma.

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.

Prenatal Fish Oil Supplementation, Maternal COX1 Genotype, and Childhood Atopic Dermatitis: A Secondary Analysis of a Randomized Clinical Trial.

Importance: Eicosanoids have a pathophysiological role in atopic dermatitis (AD), but it is unknown whether this is affected by prenatal ω-3 long-chain polyunsaturated fatty acid (n-3 LCPUFA; ie, fish oil) supplementation and genetic variations in the cyclooxygenase-1 (COX1) pathway. Objective: To explore the association of n-3 LCPUFA supplementation during pregnancy with risk of childhood AD overall and by maternal COX1 genotype. Design, Setting, and Participants: This prespecified secondary analysis of a randomized clinical trial included mother-child pairs from the Danish Copenhagen Prospective Studies on Asthma in Childhood 2010 birth cohort, with prospective follow-up until children were aged 10 years. In the trial, maternal and child COX1 genotypes were determined, and urinary eicosanoids were quantified when the child was 1 year of age. The present study was conducted from January 2019 to December 2021, and data were analyzed from January to September 2023. Intervention: A total of 736 pregnant women at 24 weeks' gestation were randomized 1:1 to 2.4 g of n-3 LCPUFA (fish oil) or placebo (olive oil) per day until 1 week post partum. Main Outcomes and Measures: Risk of childhood AD until age 10 years overall and by maternal COX1 genotype. Results: At age 10 years, 635 children (91%; 363 [57%] female) completed the clinical follow-up, and these mother-child pairs were included in this study; 321 (51%) were in the intervention group and 314 (49%) in the control group. Pregnancy n-3 LCPUFA supplementation was associated with lower urinary thromboxane A2 metabolites at age 1 year (ß, -0.46; 95% CI, -0.80 to -0.13; P = .006), which was also associated with COX1 rs1330344 genotype (ß per C allele, 0.47; 95% CI, 0.20-0.73; P = .001). Although neither n-3 LCPUFA supplementation (hazard ratio [HR], 1.00; 95% CI, 0.76-1.33; P = .97) nor maternal COX1 genotype (HR, 0.94; 95% CI, 0.74-1.19; P = .60) was associated with risk of childhood AD until age 10 years, there was evidence of an interaction between these variables (P < .001 for interaction). Among mothers with the TT genotype, risk of AD was reduced in the n-3 LCPUFA group compared with the placebo group (390 mother-child pairs [61%]; HR, 0.70; 95% CI, 0.50-0.98; P = .04); there was no association for mothers with the CT genotype (209 [33%]; HR, 1.29; 95% CI, 0.79-2.10; P = .31), and risk was increased among offspring of mothers with the CC genotype (37 [6%]; HR, 5.77; 95% CI, 1.63-20.47; P = .007). There was a significant interaction between n-3 LCPUFA supplementation and child COX1 genotype and development of AD (P = .002 for interaction). Conclusions and Relevance: In this secondary analysis of a randomized clinical trial, the association of prenatal n-3 LCPUFA supplementation with risk of childhood AD varied by maternal COX1 genotype. The findings could be used to inform a personalized prevention strategy of providing supplementation only to pregnant individuals with the TT genotype. Trial Registration: ClinicalTrials.gov: NCT00798226.