Longitudinal analyses of development of the immune system during the first five years of life in relation to lifestyle.

BACKGROUND: Changes in immune cell composition during the immunological window within the first years after birth are not fully understood, especially the effect that different lifestyles might have on immune cell functionality. METHODS: Peripheral blood mononuclear cells from mothers and their children at birth and at two anvd five years were analyzed by mass cytometry. Immune cell composition and functionality was analyzed according to family lifestyle (anthroposophic and non-anthroposophic). RESULTS: We found no significant differences in the proportions of major immune lineages between anthroposophic and non-anthroposophic children at each time point, but there were clear changes over time in the proportions of mononuclear leukocytes, especially in B-cells and T lymphocytes. Phenotypic distances between cord blood and maternal blood were high at birth but decreased sharply the first two years, indicating strong phenotypic convergence with maternal cells. We found that children exhibited similar stimulation responses at birth, but subsequently segregated into two discrete functional trajectories. Trajectory 1 was associated with a decrease in tumor necrosis factor alpha (TNFa) production by CD4+ T- and NK-cells, while Trajectory 2 depicted an increase in the production of IL-2 and interferon gamma (INFg) by T-cells. In both trajectories, there was an increase in IL-17A production by T-cells resulting in prominent differences at five years of age. CONCLUSIONS: This exploratory study suggests that leukocyte frequencies and cell phenotypes change with age in the same way across all children, while functional development follows one of two discrete trajectories that largely segregate by family lifestyle, supporting the hypothesis that early environmental exposures imprint immune cell function which may contribute to IgE sensitization. Our results also support that the first two years are critical for the environmental exposures to imprint the immune cells. Further studies with larger sample sizes are required to validate our findings.

Prevalence and Progression of Recurrent Abdominal Pain, From Early Childhood to Adolescence.

BACKGROUND & AIMS: Little is known about the natural history of childhood recurrent abdominal pain (RAP). We investigated the prevalence and progression of childhood RAP and its association with Rome III abdominal pain-related functional gastrointestinal disorders (AP-FGID) and irritable bowel syndrome (IBS) during adolescence. METHODS: We collected data from a prospective population-based birth cohort study of 4089 children, born from 1994 through 1996 in Sweden. We analyzed data from 2455 children with complete follow-up evaluation at ages 1, 2, 12, and 16 years and no parent-reported diagnoses of inflammatory bowel diseases or celiac disease at ages 12 or 16 years. A subpopulation of 2374 children who had answered questions based on the Rome III criteria at age 16 years was identified. We assessed RAP at 3 assessment points and defined it as parent-reported attacks of colic in early childhood (1-2 years) and as self-reported weekly abdominal pain at ages 12 years and 16 years. AP-FGID at age 16 years was defined according to the Rome III criteria. RESULTS: RAP was reported by 26.2% of children on at least 1 of 3 assessment points, of which 11.3% reported symptoms more than once. Children with RAP at 12 years had persistent symptoms at 16 years in 44.9% of cases and increased risks for RAP (relative risk, 2.2; 95% CI, 1.7-2.8), any AP-FGID (relative risk, 2.6; 95% CI, 1.9-3.6), and IBS (relative risk, 3.2; 95% CI, 2.0-5.1) at 16 years. Early childhood RAP was not associated significantly with any outcome. CONCLUSIONS: RAP affects many children from early childhood through age 16 years, but most children do not have persistent symptoms throughout childhood. RAP at age 12 years is a risk factor for RAP, any Rome III AP-FGID, and IBS, at age 16 years.

DNA Methylation Levels in Mononuclear Leukocytes from the Mother and Her Child Are Associated with IgE Sensitization to Allergens in Early Life.

DNA methylation changes may predispose becoming IgE-sensitized to allergens. We analyzed whether DNA methylation in peripheral blood mononuclear cells (PBMC) is associated with IgE sensitization at 5 years of age (5Y). DNA methylation was measured in 288 PBMC samples from 74 mother/child pairs from the birth cohort ALADDIN (Assessment of Lifestyle and Allergic Disease During INfancy) using the HumanMethylation450BeadChip (Illumina). PBMCs were obtained from the mothers during pregnancy and from their children in cord blood, at 2 years and 5Y. DNA methylation levels at each time point were compared between children with and without IgE sensitization to allergens at 5Y. For replication, CpG sites associated with IgE sensitization in ALADDIN were evaluated in whole blood DNA of 256 children, 4 years old, from the BAMSE (Swedish abbreviation for Children, Allergy, Milieu, Stockholm, Epidemiology) cohort. We found 34 differentially methylated regions (DMRs) associated with IgE sensitization to airborne allergens and 38 DMRs associated with sensitization to food allergens in children at 5Y (Sidak p ≤ 0.05). Genes associated with airborne sensitization were enriched in the pathway of endocytosis, while genes associated with food sensitization were enriched in focal adhesion, the bacterial invasion of epithelial cells, and leukocyte migration. Furthermore, 25 DMRs in maternal PBMCs were associated with IgE sensitization to airborne allergens in their children at 5Y, which were functionally annotated to the mTOR (mammalian Target of Rapamycin) signaling pathway. This study supports that DNA methylation is associated with IgE sensitization early in life and revealed new candidate genes for atopy. Moreover, our study provides evidence that maternal DNA methylation levels are associated with IgE sensitization in the child supporting early in utero effects on atopy predisposition.

Maternal allergen-specific IgG might protect the child against allergic sensitization.

BACKGROUND: Analysis of allergen-specific IgE responses in birth cohorts with microarrayed allergens has provided detailed information regarding the evolution of specific IgE responses in children. High-resolution data regarding early development of allergen-specific IgG are needed. OBJECTIVE: We sought to analyze IgG reactivity to microarrayed allergens in mothers during pregnancy, in cord blood samples, in breast milk, and in infants in the first years of life with the aim to investigate whether maternal allergen-specific IgG can protect against IgE sensitization in the offspring. METHODS: Plasma samples from mothers during the third trimester, cord blood, breast milk collected 2 months after delivery, and plasma samples from children at 6, 12, and 60 months of age were analyzed for IgG reactivity to 164 microarrayed allergens (ImmunoCAP ISAC technology) in 99 families of the Swedish birth cohort Assessment of Lifestyle and Allergic Disease During Infancy (ALADDIN). IgE sensitizations to microarrayed allergens were determined at 5 years of age in the children. RESULTS: Allergen-specific IgG reactivity profiles in mothers, cord blood, and breast milk were highly correlated. Maternal allergen-specific IgG persisted in some children at 6 months. Children's allergen-specific IgG production occurred at 6 months and reflected allergen exposure. Children who were IgE sensitized against an allergen at 5 years of age had significantly higher allergen-specific IgG levels than nonsensitized children. For all 164 tested allergens, children from mothers with increased (>30 ISAC standardized units) specific plasma IgG levels against an allergen had no IgE sensitizations against that allergen at 5 years of age. CONCLUSION: This is the first detailed analysis of the molecular IgG recognition profile in mothers and their children in early life. High allergen-specific IgG reactivity in the mother's plasma and breast milk and in cord blood seemed to protect against allergic sensitization at 5 years of age.

Relevance of low specific IgE levels to egg, milk and peanut in infancy.

BACKGROUND: IgE sensitization is usually associated with allergy-related diseases, but may also occur in asymptomatic individuals. The clinical importance of IgE antibody concentrations in the interval 0.1-0.34 kU/L in early life in relation to allergy development is poorly evaluated. OBJECTIVE: To assess the relevance of low specific IgE (s-IgE) to hen's egg, cow's milk and peanut at 6 months of age for development of sensitization and allergy-related disease during early childhood. METHODS: s-IgE concentrations to relevant allergens from blood samples taken at 6 months and 1, 2 and 5 years from children in the prospective ALADDIN cohort were divided into three categories: non-sensitized (<0.1 kU/L), low sensitized (0.1-0.34 kU/L) and sensitized (≥0.35 kU/L) and allergy-related disease assessed. RESULTS: A total of 372 children were included in this study. Compared with non-sensitized children at 6 months of age, children with low levels of allergen specific IgE (0.1-0.34 kU/L) to food allergens, especially to egg, at 6 months of age were associated with development of sensitization to aeroallergens at 5 years of age (10/14 [71%] vs 39/250 [15%]). In addition, children with low levels to egg or milk at 6 months were more often sensitized to the respective allergen at 1 year of age and, regarding low levels to egg, also to the development of eczema (6/18 [33%] vs 29/292 [10%]). CONCLUSION & CLINICAL RELEVANCE: IgE antibody concentrations in the interval 0.1-0.34 kU/L to food allergens in infancy seem to increase the probability of sensitization to aeroallergens and, regarding low levels to egg, also of eczema during early childhood. Thus, IgE levels during the first year of life, although below 0.35 kU/L, can provide additional allergy-related prognostic information.

Sublingual immunotherapy alters salivary IgA and systemic immune mediators in timothy allergic children.

BACKGROUND: Immunomodulatory effects of sublingual immunotherapy on systemic and mucosal mediators in allergic children are largely unexplored. The aim of this study was to investigate allergy-related cytokine and chemokine levels, as well as IgA-responses upon a 3-year treatment with timothy grass pollen sublingual immunotherapy in children with allergic rhinoconjunctivitis. METHODS: From children included in the GRAZAX® Asthma Prevention study, blood and saliva samples were analyzed at inclusion, after 3 years of treatment, and 2 years after treatment ending. By means of Luminex and ELISA methodologies, allergy-related cytokines and chemokines were measured in plasma samples and allergen-stimulated peripheral blood mononuclear cell supernatants. Furthermore, studies of total, secretory, and Phl p 1-specific salivary IgA antibodies were performed using the same methods. RESULTS: GRAZAX® -treated children exhibited significantly higher levels of Phl p 1-specific salivary IgA and serum IgG4 , along with significantly lower skin prick test positivity, after 3 years of treatment and 2 years after treatment cessation. Additionally, plasma levels of the Th1-associated chemokines CXCL10 and CXCL11 were significantly higher in treated than untreated children at these time points. Timothy-induced ratios of IL-5/IL-13 over IFN-γ were significantly decreased after 3 years with active treatment, as were symptoms of allergic rhinitis in terms of both severity and visual analogue scale scores. However, no consistent correlations were found between the clinical outcomes and immunologic parameters. CONCLUSION: Phleum pratense sublingual immunotherapy in grass pollen allergic children modulates the immune response in the oral mucosa as well as systemically-by increasing Th1-responses, decreasing Th2-responses, and inducing immunoregulatory responses-all signs of tolerance induction.

Placental inflammation, lifestyle, maternal and early child sensitisation to allergens - the assessment of lifestyle and allergic disease during infancy birth cohort.

AIM: To investigate (i) whether maternal sensitisation to allergens, and lifestyle can influence the risk of acute and chronic inflammation of the placenta, in the forms of chorioamnionitis and villitis, respectively, and (ii) whether these placental inflammations are associated with the outcome of sensitisation for the child during preschool age. METHODS: Placentas from term uncomplicated pregnancies (n = 275) in the assessment of lifestyle and allergic disease during infancy study were analysed for the presence of acute chorioamnionitis and chronic villitis. Stepwise logistic regression was performed to estimate the relative risk of placental inflammation in relation to maternal allergic sensitisation and lifestyle, and the association between placental inflammation and sensitisation of the child up to five years of age. RESULTS: Parity and delivery at home were independently associated with chorioamnionitis, home delivery only with the low grade. Maternal allergic sensitisation was associated with increased risk of villitis in the bivariable model, however, not in the multivariable model. No significant associations were detected between placental inflammation and the outcome of sensitisation to allergens at five years of age. CONCLUSION: Our data do not support the hypothesis that the increased risk for sensitisation of a child when the mother is allergic is mediated via placental inflammation.

Histone Acetylation of Immune Regulatory Genes in Human Placenta in Association with Maternal Intake of Olive Oil and Fish Consumption.

Maternal diet modifies epigenetic programming in offspring, a potentially critical factor in the immune dysregulation of modern societies. We previously found that prenatal fish oil supplementation affects neonatal T-cell histone acetylation of genes implicated in adaptive immunity including PRKCZ, IL13, and TBX21. In this study, we measured H3 and H4 histone acetylation levels by chromatin immunoprecipitation in 173 term placentas collected in the prospective birth cohort, ALADDIN, in which information on lifestyle and diet is thoroughly recorded. In anthroposophic families, regular olive oil usage during pregnancy was associated with increased H3 acetylation at FOXP3 (p = 0.004), IL10RA (p = 0.008), and IL7R (p = 0.007) promoters, which remained significant after adjustment by offspring gender. Furthermore, maternal fish consumption was associated with increased H4 acetylation at the CD14 gene in placentas of female offspring (p = 0.009). In conclusion, prenatal olive oil intake can affect placental histone acetylation in immune regulatory genes, confirming previously observed pro-acetylation effects of olive oil polyphenols. The association with fish consumption may implicate ω-3 polyunsaturated fatty acids present in fish oil. Altered histone acetylation in placentas from mothers who regularly include fish or olive oil in their diets could influence immune priming in the newborn.

Morning Salivary Cortisol in Young Children: Reference Values and the Effects of Age, Sex, and Acute Bronchiolitis.

OBJECTIVE: To identify morning salivary cortisol reference values in infancy and at 2 years of age and to investigate the influence of age, sex and acute bronchiolitis. STUDY DESIGN: In this South-East Norwegian cohort study, 308 children hospitalized with moderate to severe acute bronchiolitis in infancy in 2010-2011 were compared with 223 healthy controls included in 2012 by measuring morning salivary cortisol levels at inclusion and at 2 years of age. Samples were collected shortly after awakening after 6 am. The influences of age, sex, and acute bronchiolitis were assessed by regression analysis. RESULTS: In infancy, cortisol values were higher in acute bronchiolitis, with an age- and sex-adjusted weighted mean group difference of 13.9 nmol/L (95% CI 8.1-19.7; P < .0001). The median level in reference group was 23.7 nmol/L (95% CI 9.7-119.6). At 2 years of age, sex but not inclusion groups differed, with significantly higher values in girls. The weighted mean of all boys' cortisol levels was 32.4 nmol/L, (95% CI 30.5-34.3), and all girls' levels were 36.9 nmol/L (95% CI 34.7-39.2; P < .003). CONCLUSIONS: Salivary cortisol levels were higher at 2 years of age than in infancy in the reference group, were higher in girls than in boys at 2 years of age, and were higher in infants at the time of acute bronchiolitis than in healthy infants. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00817466.

Vaccination and allergy: EAACI position paper, practical aspects.

Immunization is highly effective in preventing infectious diseases and therefore an indispensable public health measure. Allergic patients deserve access to the same publicly recommended immunizations as non-allergic patients unless risks associated with vaccination outweigh the gains. Whereas the number of reported possible allergic reactions to vaccines is high, confirmed vaccine-triggered allergic reactions are rare. Anaphylaxis following vaccination is rare, affecting <1/100 000, but can occur in any patient. Some patient groups, notably those with a previous allergic reaction to a vaccine or its components, are at heightened risk of allergic reaction and require special precautions. Allergic reactions, however, may occur in patients without known risk factors and cannot be predicted by currently available tools. Unwarranted fear and uncertainty can result in incomplete vaccination coverage for children and adults with or without allergy. In addition to concerns about an allergic reaction to the vaccine itself, there is fear that routine childhood immunization may promote the development of allergic sensitization and disease. Thus, although there is no evidence that routine childhood immunization increases the risk of allergy development, such risks need to be discussed.