Perinatal risk factors for wheezing phenotypes in the first 8 years of life.

BACKGROUND: A novel data-driven approach was used to identify wheezing phenotypes in pre-schoolchildren aged 0-8 years, in the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort. Five phenotypes were identified: never/infrequent wheeze, transient early wheeze, intermediate onset wheeze, persistent wheeze and late onset wheeze. It is unknown which perinatal risk factors drive development of these phenotypes. OBJECTIVE: The objective of the study was to assess associations of perinatal factors with wheezing phenotypes and to identify possible targets for prevention. METHODS: In the PIAMA study (n = 3963), perinatal factors were collected at 3 months, and wheezing was assessed annually until the age of 8 years. Associations between perinatal risk factors and the five wheezing phenotypes were assessed using weighted multinomial logistic regression models. Odds ratios were adjusted for confounding variables and calculated with 'never/infrequent wheeze' as reference category. RESULTS: Complete data were available for 2728 children. Risk factors for transient early wheeze (n = 455) were male gender, maternal and paternal allergy, low maternal age, high maternal body mass index, short pregnancy duration, smoking during pregnancy, presence of older siblings and day-care attendance. Risk factors for persistent wheeze (n = 83) were male gender, maternal and paternal allergy, and not receiving breastfeeding for at least 12 weeks. Intermediate onset wheeze (n = 98) was associated with a lower birth weight and late onset wheeze (n = 45) with maternal allergy. CONCLUSION AND CLINICAL RELEVANCE: We identified different risk factors for specific childhood wheezing phenotypes. Some of these are modifiable, such as maternal age and body mass index, smoking, day-care attendance and breastfeeding, and may be important targets for prevention programmes.

T cell responses to major peanut allergens in children with and without peanut allergy.

BACKGROUND: T cell responses involved in peanut allergy are poorly understood. OBJECTIVE: To investigate T cell responses towards major peanut allergens in peanut-allergic (PA) subjects compared with peanut-sensitized (PS) non-allergic children and non-atopic (NA) controls. METHODS: Eighteen PA children, seven non-allergic PS children and 11 NA adults were included. Peripheral blood mononuclear cells were stimulated with a crude peanut extract (CPE). Short-term T cell lines were generated and subsequently stimulated with CPE and purified Ara h 1, Ara h 2, Ara h 3 and Ara h 6. The proliferation and production of IL-13, IFN-gamma, IL-10 and TNF-alpha were analysed. RESULTS: Proliferation to CPE and major allergens was enhanced in PA subjects. The primary response to CPE was comparable with PS subjects, with increased production of IL-13 and IFN-gamma compared with NA. Production of IL-10 was not observed. In short-term T cell lines, the response to CPE was stronger in PA than in PS and NA subjects. Only PA children had a detectable response to major peanut allergens, characterized by IL-13 production. The response was the highest after Ara h 3 stimulation, and the lowest after Ara h 2 stimulation. No significant correlation was observed between peanut-specific IgE levels and T cell responses to CPE. CONCLUSION: T cell responses to CPE in PA and PS children were characterized by Th1 and Th2 cytokines. Only PA children showed enhanced Th2 responses to Ara h 1, Ara h 3 and Ara h 6.

Lactic acid bacteria differ in their ability to induce functional regulatory T cells in humans.

BACKGROUND: Trials with probiotic lactic acid bacteria have yielded different results, which may be due to the strains used. Lactobacilli and bifidobacteria are known to be potent modulators of the immune system. The capacity of these bacteria used as probiotics to influence both T helper type 1 (Th1)- and Th2-mediated diseases has been shown before. However, the ability of strains to induce forkhead box P3 (FOXP3(+)) expressing regulatory T cells has not yet been investigated. OBJECTIVE: Test the inherent differences between strains in their capacity to induce functional regulatory T cells in human peripheral blood mononuclear cells (PBMC). METHODS: Human PBMC were co-cultured in vitro with either Bifidobacterium lactis W51, Lactobacillus acidophilus W55 or Lactobacillus plantarum W62 or an Escherichia coli control strain. The percentage of FOXP3(+) cells, the origin of the induced cells and the functionality of these cells were assessed. Results Probiotic strains differ in their capacity to induce regulatory T cells. FOXP3(+) cells were induced from CD25(-) cells and were able to suppress effector T cells. Naturally occurring regulatory T cells were not affected by co-culture with lactobacilli. IL-10 concentrations found in the supernatant showed a trend towards the same differences between strains. Blockade of IL-10 did not influence the up-regulation of FOXP3. No differences between lactic acid bacteria were found in IL-17, IFN-gamma or IL-13. CONCLUSIONS: Some probiotic strains are potent inducers of regulatory cells, while others are not. The clear differences between strains imply that an in vitro characterization of probiotic strains before application is recommended.

Breast feeding, parental allergy and asthma in children followed for 8 years. The PIAMA birth cohort study.

BACKGROUND: It is unclear how the association between breast feeding and asthma develops with age of the child and how this association over time is influenced by maternal or paternal allergy. These factors--the age of the child and maternal or paternal allergy--might partly explain the conflicting results observed in cross-sectional studies. METHODS: The study population consisted of 3115 Dutch children born in 1996/1997 who participated in the PIAMA (Prevention and Incidence of Asthma and Mite Allergy) birth cohort study. Data on breast feeding and asthma (based on wheeze, dyspnoea and prescription of inhaled steroids) were collected by yearly questionnaires. At 8 years, specific immunoglobulin E (IgE) to airborne allergens and bronchial responsiveness were measured. Data were analysed by logistic regression and generalised estimating equations (GEEs), and stratified by maternal and paternal allergic status. RESULTS: 35% (n = 1081) of the children were breast fed for >16 weeks. At 8 years of age, 12.6% (n = 392) had asthma. Breast feeding (>16 weeks vs no breast feeding) was significantly associated with a lower asthma prevalence from 3 to 8 years of age, in children of both non-allergic and allergic mothers. The inverse association between breast feeding and sensitisation to airborne allergens at 8 years was non-significant. Breast feeding was not associated with bronchial hyper-responsiveness. No interaction between breast feeding and gender, maternal allergy or paternal allergy was observed in any of the associations. CONCLUSIONS: Breast feeding is associated with a lower asthma risk in children until 8 years of age without evidence of attenuation and regardless of the family history of allergy.

Exploring the role of polymorphisms in ficolin genes in respiratory tract infections in children.

Ficolins are pattern-recognition molecules that appear to be relevant for innate immune defence against infections. The ficolin genes in Caucasians are polymorphic and genetic variations may have functional consequences, both in relation to function and concentration. Low levels of Ficolin-2 have been suggested to associate with recurrent respiratory tract infections (RTI), whereas data on Ficolin-3 are still very limited. We investigated the association between variation in genes encoding Ficolin-2 (FCN2) and Ficolin-3 (FCN3) and frequency of RTI during the first 4 years of life. The study population consisted of 900 children from a large, population-based birth cohort of Dutch children, followed prospectively from birth to 4 years of age. The number of RTI was assessed by annual parental questionnaires. Nine single nucleotide polymorphisms in FCN2 and two in FCN3, all based on functionality or haplotype-tagging characteristics, were determined and haplotypes constructed. We found that single nucleotide polymorphisms in FCN2 and FCN3 were not associated with increased risk of RTI during the first 4 years of life. No difference existed between haplotype-frequencies of FCN2 and FCN3 in children grouped according to the reported number of RTI. In conclusion, at a population level, genetic variation in ficolin genes FCN2 and FCN3 do not seem to contribute to the risk of RTI in Caucasian children.

Effects of pets on asthma development up to 8 years of age: the PIAMA study.

BACKGROUND: Recall bias may provide discrepant relationships of pet exposure with sensitization and asthma development. We studied prospectively effects of pets at home on development of sensitization, asthma and respiratory symptoms from birth up to age 8 years. METHODS: Event history analysis was performed on annually registered data of 2951 children, participating in the PIAMA birth cohort study. RESULTS: Children with a cat or dog at home at 3 months of age had a significantly lower prevalence of sensitization to inhalant allergens at age 8, but not of asthma. A cat decreased the risk of house dust mite sensitization at age 8 [odds ratio (OR) = 0.68, 95% confidence interval (CI) 0.49-0.95], a dog of pollen sensitization (OR = 0.49, 95% CI: 0.29-0.83). A cat or dog at home did not significantly affect asthma incidence in each subsequent year. From 2 years of age onwards, the incidence of wheeze (OR = 1.52, 95% CI: 1.12-2.05) and a dry cough at night (OR = 1.28, 95% CI: 1.05-1.57) was higher in children with a dog, whereas removal of a dog increased the risk of developing asthma symptoms. Comparing analyses using prospectively and retrospectively collected data on diagnosed asthma showed important recall bias. CONCLUSIONS: Our prospective study shows a protective effect of early presence of pets at home on sensitization to inhalant allergens, but no prevention of asthma development. Furthermore, children with pets had more frequent transient or intermittent asthma symptoms. Parental report of asthma by recall may provide spurious results of these associations.

Asthma at 8 years of age in children born by caesarean section.

BACKGROUND: Caesarean section might be a risk factor for asthma because of delayed microbial colonisation, but the association remains controversial. A study was undertaken to investigate prospectively whether children born by caesarean section are more at risk of having asthma in childhood and sensitisation at the age of 8 years, taking into account the allergic status of the parents. METHODS: 2917 children who participated in a birth cohort study were followed for 8 years. The definition of asthma included wheeze, dyspnoea and prescription of inhaled steroids. In a subgroup (n = 1454), serum IgE antibodies for inhalant and food allergens were measured at 8 years. RESULTS: In the total study population, 12.4% (n = 362) of the children had asthma at the age of 8 years. Caesarean section, with a total prevalence of 8.5%, was associated with an increased risk of asthma (OR 1.79; 95% CI 1.27 to 2.51). This association was stronger among predisposed children (with two allergic parents: OR 2.91; 95% CI 1.20 to 7.05; with only one: OR 1.86; 95% CI 1.12 to 3.09) than in children with non-allergic parents (OR 1.36; 95% CI 0.77 to 2.42). The association between caesarean section and sensitisation at the age of 8 years was significant only in children of non-allergic parents (OR 2.14; 95% CI 1.16 to 3.98). CONCLUSIONS: Children born by caesarean section have a higher risk of asthma than those born by vaginal delivery, particularly children of allergic parents. Caesarean section increases the risk for sensitisation to common allergens in children with non-allergic parents only.

Gene expression in CD4+ T-cells reflects heterogeneity in infant wheezing phenotypes.

Although a marked increase in the reporting of wheezing symptoms since the mid-1970s has been described, the underlying immunopathology of the different wheezing phenotypes has not been clarified. Since differences in gene expression might be involved, the objective of the present study was to identify gene expression profiles in CD4+ T-cells from two distinct infant wheezing phenotypes. The gene expression profiles of peripheral CD4+ T-cells were compared by means of microarray analysis of six transient wheezers, six persistent wheezers and seven healthy controls. The differentially expressed genes were subsequently validated by RT-PCR. The differential gene expression profiles reflected common immunological pathways involved in apoptosis or proliferation of T-cells. Furthermore, both wheezing phenotypes showed decreased expression of the complement component 5 receptor 1 gene, a gene involved in the regulation of bronchial responsiveness. Moreover, differences in gene expression profiles were found in genes involved in the immune response against respiratory syncytial virus, such as those encoding signal transducer and activator of transcription 1 and an inflammatory mediator showing enhanced production in asthma (prostaglandin E(2) receptor 2). The present findings suggest that clinical symptoms of wheeze are reflected in common immunological pathways, whereas differences between wheezing phenotypes are, in part, reflected in distinct gene expression profiles.

[Sublingual immunotherapy in children with asthma or rhinoconjunctivitis: not enough evidence because of poor quality of the studies; a systematic review of literature]. / Sublinguale immunotherapie bij kinderen met astma of rinoconjunctivitis: onvoldoende evidence door matige kwaliteit van de verrichte studies; een systematisch literatuuroverzicht.

OBJECTIVE: To determine the evidence of the efficacy and safety of sublingual immunotherapy (SLIT) as a curative therapy for allergies in children. DESIGN: Systematic review. METHOD: All randomised, double blind and placebo-controlled studies (DBRPCT's) on SLIT in asthma or rhinoconjunctivitis in children were selected from Medline, Embase and Cochrane Central Register of Controlled Trials. Also references of the found articles were used. The selected studies were assessed for quality and the different outcomes were evaluated. RESULTS: 13 DBRPCT's on SLIT in children were selected, 5 studies on children with house dust mite allergy and 8 studies on children with grass pollen allergy. There was considerable heterogeneity among the different studies with respect to the choice and definition of outcome criteria. The quality of the included studies was moderate. After treatment with SLIT, especially reported symptoms decreased without improvement of objective parameters. Positive results originated especially from significant differences within the intervention group before and after treatment. CONCLUSION: It was not possible to substantiate the claim of authors of the studies regarding the favourable effects of SLIT in children with asthma or rhinoconjunctivitis, since all studies had serious methodological flaws. However, the studies showed that SLIT seems to be safe in children in the doses applied.

Bacille-Calmette-Guerin vaccination and the development of allergic disease in children: a randomized, prospective, single-blind study.

BACKGROUND: The increase in the prevalence of allergic diseases in countries with a so-called western lifestyle may be due to a decrease in exposure to infectious agents in early life. OBJECTIVE: To establish the effect of Bacille-Calmette-Guerin (BCG) vaccination in 6-week-old high-risk infants in a prospective single-blind, randomized, placebo-controlled trial on the prevalence of allergic disease at the age of 4 and 18 months. METHODS: Subjects were 121 predominantly Caucasian high-risk newborns, having either a mother, or both a father and at least one sibling with past or present allergic disease. BCG or placebo was administered at the age of 6 weeks, and repeated once when both a post-vaccination scar and a positive TB skin test were absent at the age of 4 months. RESULTS: At the age of 18 months, the prevalence of allergic disease was not significantly different between the two groups. A trend towards less eczema (P=0.07) and significantly less use of medication for eczema was shown in the BCG group compared with the placebo group (P=0.04). CONCLUSION: A single (or once repeated) BCG vaccination in 6-week-old high-risk Caucasian infants was not associated with a 50% reduction in the prevalence of allergic disease. However, there could be a smaller beneficial effect of BCG, especially because a trend towards less eczema and significantly less use of medication for eczema was shown. For definite proof, a larger study should be carried out.

Children with peanut allergy recognize predominantly Ara h2 and Ara h6, which remains stable over time.

BACKGROUND: In peanut-allergic adults, IgE is mainly directed to Ara h1 and Ara h2. More recently, a role for Ara h6 has been suggested. In contrast to adults, IgE in children can fluctuate over time. Therefore, children may have a more dynamic reactivity to peanut. OBJECTIVE: To examine the IgE reactivity to major peanut allergens in peanut-allergic children at two subsequent time-points. METHODS: Twenty children (3-15 years old) with peanut allergy, confirmed by a double-blind placebo-controlled food challenge (DBPCFC), were included. Just before and 20 months after DBPCFC, IgE reactivity to purified Ara h1, Ara h2, Ara h3 and Ara h6 was studied by immunoblots and skin prick tests (SPTs). RESULTS: Before DBPCFC, all peanut-allergic children showed IgE reactivity to Ara h2; Ara h6 was recognized by 16 children, and Ara h1 and Ara h3 by 10 children. After 20 months, peanut-specific IgE levels (median 23 kU/L) and the individual recognition of major allergens were comparable with the levels and recognition before challenge (median 28.2 kU/L). SPT with Ara h2 and Ara h6 was positive in most children, whereas SPT with Ara h1 and Ara h3 was positive in approximately half of the children. Ara h6 induced the largest weals. None of the parameters were related to the severity of peanut allergy. CONCLUSION: Ara h2 and Ara h6 are the most frequently recognized major peanut allergens in children. The individual reactivity to the major peanut allergens remained stable over time, despite DBPCFC.

Selection of probiotic bacteria for prevention of allergic diseases: immunomodulation of neonatal dendritic cells.

Modification of intestinal microbiota early in life by administration of probiotic bacteria may be a potential approach to prevent allergic disease. To select probiotic bacteria for in vivo purposes, we investigated the capacity of probiotic bacteria to interact with neonatal dendritic cells (DC) and studied the ensuing T cell polarizing effect. Immature DC were generated from cord blood-derived monocytes and maturation was induced by maturation factors (MF), lipopolysaccharide (LPS) plus MF and Bifidobacterium bifidum, B. infantis, Lactobacillus salivarius, Lactococcus lactis alone or combined with MF. After 12 days of co-culture with DC and Staphylococcus aureus enterotoxin B (SEB) as antigenic stimulus, cytokine production by autologous T cells was determined by intracellular cytokine staining. Additionally, cells were stimulated with CD3 and CD28 monoclonal antibodies and cytokines were measured in supernatants by multiplex assay. The probiotic strains induced partial maturation of DC. Full maturation of DC was induced for all strains tested when MF was added. The percentage of interleukin (IL)-4 producing T cells was lower in T cell cultures stimulated with B. bifidum matured DC compared to MF and LPS matured DC, which coincided with a higher percentage of interferon (IFN)-gamma-producing T cells. Furthermore, T cells stimulated by B. bifidum matured DC produced significantly more IL-10 compared to MF matured DC. Selected species of the Bifidobacterium genus prime in vitro cultured neonatal DC to polarize T cell responses and may therefore be candidates to use in primary prevention of allergic diseases.

The interleukin-10 inducing effect of transforming growth factor-beta on human naive CD4+ T cells from cord blood is restricted to the TH1 subset.

Transforming growth factor (TGF-beta) seems to play a role in the regulation of immune responses, mainly by its suppressive function towards cells of the immune system. However, both in mice and human, conflicting data are published on the capacity of TGF-beta to induce interleukin (IL)-10 secretion in both naive and skewed T cell populations. Our aim was to test the IL-10-inducing capacity of TGF-beta in both naive and skewed cord blood mononuclear cells (CBMCs) and elucidate the mechanism by which TGF-beta exerts its effect. Therefore, naive CBMCs and CBMCs during skewing under T helper 1 (Th1) and Th2 polarizing conditions were stimulated with CD3 and/or CD28 in the presence or absence of TGF-beta. Proliferation, cytokine production and mRNA expression of transcription factors was measured. TGF-beta enhanced the IL-10 production in Th1 and naive cells only, and suppressed the T(H)1 phenotype as demonstrated in cytokine levels and T-box expression in T cells (T-bet) expression. Interestingly, forkhead box p3 (Foxp3) expression tended to increase in both Th1 and Th2 cells. These data indicate that TGF-beta can induce a regulatory phenotype in both naive and Th1-polarized cells derived from cord blood. The induction of IL-10 was not observed in Th2-polarized phenotype, indicating that TGF-beta might be especially of interest for immunomodulation in Th1 cells.

[Double-blind placebo-controlled cow's milk challenge for children in general hospitals]. / Dubbelblinde placebogecontroleerde koemelkprovocaties bij kinderen in een algemeen ziekenhuis.

Every child with possible food allergies has the right to a double-blind, placebo-controlled cow's milk challenge. This test can be performed in the paediatric ward of a non-academic hospital. Challenge with other foodstuffs can lead to more serious side effects and therefore should be considered in a general hospital setting only after extensive experience with double-blind, placebo-controlled challenge for cow's milk has been obtained. Other items of international discussion on double-blind, placebo-controlled challenge in children are: the natural development of tolerance for cow's milk, IgE- versus non-IgE-mediated cow's milk allergy, and the exacerbation of pre-existing eczema during and after double-blind, placebo-controlled challenge.

Respiratory atopic disease, Ascaris-immunoglobulin E and tuberculin testing in urban South African children.

BACKGROUND: Epidemiological relation of intestinal helminth infection and atopic disease, both associated with a T-helper (Th) 2 immune response, is controversial, as it has been reported that helminth infection may either suppress or pre-dispose to atopic disease. This relation has not been tested in an area with a high burden of Mycobacterium tuberculosis (MTB) infection, a known Th1-stimulating infection. OBJECTIVE: To study the association of intestinal helminth infection and atopic disease in a community where helminth infection is endemic and MTB infection is high. METHODS: Three-hundred and fifty-nine randomly selected children aged 6-14 years from a poor urban suburb were tested with allergy questionnaire, skin prick test (SPT) to common aeroallergens, Ascaris-specific IgE (Ascaris-sIgE), fecal examination for pathogenic intestinal helminths and tuberculin skin testing (TST). Histamine bronchoprovocation was tested in the group of children aged 10 years and older. RESULTS: were corrected for demographic variables, socioeconomic status, parental allergy, environmental tobacco smoke (ETS) exposure in the household, recent anthelminthic treatment and for clustering in the sampling unit. Results Ascaris-sIgE was elevated in 48% of children, Ascaris eggs were found in 15% and TST was positive in 53%. Children with elevated Ascaris-sIgE had significantly increased risk of positive SPT to aeroallergens, particularly house dust mite, atopic asthma (ever and recent), atopic rhinitis (ever and recent) and increased atopy-related bronchial hyper-responsiveness. In children with negative TST (<10 mm), elevated Ascaris-sIgE was associated with significantly increased risk of atopic symptoms (adjusted odds ratio (OR(adj)) 6.5; 95% confidence interval (CI) 1.9-22.4), whereas in those with positive TST (>/=10 mm) this association disappeared (OR(adj) 0.96; 95% CI 0.4-2.8). CONCLUSIONS: These results suggest that immune response to Ascaris (Ascaris-sIgE) may be a risk factor of atopic disease in populations exposed to mild Ascaris infection and that MTB infection may be protective against this risk, probably by stimulation of anti-inflammatory networks.

[Episodes of angioedema in children with C1 esterase inhibitor deficiency]. / Aanvallen van angio-oedeem bij kinderen door C1-esteraseremmerdeficiëntie.

A 6-year-old boy and a 3.5-year-old girl presented with unexplained episodes of angioedema without urticaria. Low serum C1 esterase inhibitor activity was found in both children. Family history revealed autosomal dominant inheritance in the girl. The boy had a negative family history for angioedema. C1 esterase inhibitor deficiency is a rare but serious condition that may cause oedema of the upper respiratory tract and death by asphyxiation. Episodes of angioedema occur spontaneously, usually subsiding within 48-72 h. Between episodes, the patients are symptom free. Treatment consists of substitution of synthetic C1 esterase inhibitor during episodes of edema carrying a risk of upper airway obstruction. In patients who have more than one episode of severe angioedema per month, daily treatment with tranexamic acid should be considered. Both of these patients were not receiving daily treatment.