Long-term outcomes of early childhood wheezing

Interleukin 1 receptor-like 1 rs13408661/13431828 polymorphism is associated with persistent post-bronchiolitis asthma at school age

Aim

Interleukin (IL) 1 receptor‐like 1, encoded by the IL1RL1 gene, is a receptor for IL‐33. In European birth cohorts, IL1RL1 rs102082293, rs10204137 (rs4988955), rs13424006 and rs13431828 (rs13048661) variations were associated with asthma at school age. In a Dutch multi‐centre study, IL1RL1 rs1921622 variation was associated with severe bronchiolitis. We evaluated the associations of these five IL1RL1 variations with asthma and lung function at school age after hospitalisation for bronchiolitis in infancy.

Methods

Follow‐up data, including impulse oscillometry at age 5–7 and flow‐volume spirometry at age 11–13 years, and the IL1RL1 genotype data were available for 141 children followed until 5–7 and for 125 children followed until 11–13 age years after bronchiolitis in infancy. The IL1RL1 rs10204137 and rs4988955, and the IL1RL1 rs13048661 and rs13431828, are 100% co‐segregating in the Finnish population.

Results

The variant IL1RL1 rs13048661/13431828 genotype was constantly associated with increased asthma risk by various definitions at 5–7 and 11–13 years of ages. The result was confirmed with analyses adjusted for current confounders and early‐life environment‐related factors. Statistical significances were lost, when maternal asthma and atopic dermatitis in infancy were included in the model.

Conclusion

IL1RL1 rs13048661/13431828 variation was associated with post‐bronchiolitis asthma outcomes at school age.

Epidemiology of Infections and Development of Asthma

Asthma and allergic diseases have become more prevalent, although the reasons for this increase in disease burden are not known. Understanding why these diseases have become more common requires knowledge of the disease pathogenesis. Multiple studies have identified respiratory viral infections and atypical bacteria as potential etiologic agents underlying the development of asthma (and possibly allergies). This review discusses the epidemiology and potential mechanistic studies that provide links between these infectious agents and the development (and exacerbation) of asthma. These studies provide insight into the increase in disease prevalence and have identified potential targets for future therapeutic intervention.

Increased epidermal growth factor in nasopharyngeal aspirates from infants with recurrent wheeze

Airway remodeling is known to be a consequence of repeated injury and thought to be involved in early stage of asthma. We aimed to investigate the mediators associated with airway remodeling in recurrent early wheezers. Thirty-three infants, aged 2 years or less, admitted with exacerbation of wheezing were enrolled. All of them had experienced three or more episodes of wheezing before admission. They were categorized into two groups: those who had been hospitalized two or more times for severe wheezing (N = 19) and those who had only once or never been hospitalized (N = 14). Epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), and transforming growth factor (TGF)-β1 levels in nasopharyngeal aspirates (NPA) collected on admission were measured. The difference between two patients groups divided based on their hospitalization history was assessed. We also examined these mediators in older asthmatic children (N = 15) admitted with exacerbation and their relationship with lung function parameters measured after stabilization. NPA EGF levels were significantly increased in recurrent early wheezers compared to controls. EGF, VEGF, and TGF-β1 levels were significantly higher in those with a previous history of multiple hospitalizations than in those without. In older asthmatic children, EGF levels were related with age and duration of asthma, but showed an inverse correlation with forced expiratory volume in 1 sec and forced expiratory flow between 25% and 75% of vital capacity. Our study shows that there might be significant damage during exacerbation in wheezy infants as levels of the mediators, EGF, VEGF, and TGF-β1 were higher in those who had been frequently hospitalized. It seems to suggest that those infants with severe recurrent wheezing might have chronic airway obstruction.

Polymorphism of the rs1800896 IL10 promoter gene protects children from post-bronchiolitis asthma

Viral bronchiolitis is a major cause of hospitalization in infancy, with increased asthma risk in later childhood. However, the principal mechanisms behind post-bronchiolitic asthma have remained unclear. Previously, different cytokine polymorphisms have been associated with asthma occurrence, but no previous follow-up study has investigated cytokine polymorphisms in relation to post-bronchiolitic asthma. We hypothesized that former bronchiolitis patients with cytokine gene variants associating with Th2 cell up-regulation are at asthma risk at preschool age. Our emphasis was in IL10 rs1800896, since IL-10 has an important role in immune tolerance, and lower production of IL-10 has been associated with Th2-type immunology, and accordingly, with increased asthma risk. IL10 rs1800896, IFNG rs2430561, and IL18 rs1872387 polymorphims and their associations with asthma and allergy were studied in 135 preschool-aged children hospitalized for bronchiolitis at age 0-6 months. Parents were interviewed to record asthma and allergy from infancy to present. At age 6.4 years (mean), asthma was present in 17(12.6%), atopic eczema in 47(34.8%) and allergic rhinitis in 36(26.7%) children. IL10 rs1800896 SNP associated significantly with asthma; only 1/32 (3.1%) of those with G/G genotype had asthma (P = 0.04). In logistic regression adjusted for gender, age and atopy, the carriage of allele A (rs1800896) was a significant risk factor for preschool asthma. IFNG rs2430561 or IL18 rs1872387 SNP's had no associations with asthma or allergy. In conclusion, IL10 rs1800896 SNP was significantly associated with preschool asthma after severe lower respiratory tract infection in early infancy.

Effects of wheezing in early childhood in the development of allergic rhinitis in later years

BACKGROUND

Studies on the long-term effects of wheezing in infancy have particularly focused on asthma. There isn't adequate information about the effects of wheezing in the development of allergic rhinitis in later years.

OBJECTIVE

In this study, children with wheezing in the first year of life were investigated in terms of allergic rhinitis after five years of age.

METHODS

The study consisted of children with early-transient wheezing or persistent wheezing. The study groups were evaluated in terms of allergic rhinitis with physical examination and a questionnaire translated from International Study of Asthma and Allergies in Children (ISAAC) questionnaire after five years of age.

RESULTS

The study included 50 children; 23 (46%) had early-transient wheezing and 27 (54%) had persistent wheezing. The symptoms of allergic rhinitis were reported in 13 (48%) of children with persistent wheezing but in none of children with early-transient wheezing (p < 0.05). Skin prick tests showed positive results in 4.3% of children with early-transient wheezing and in 48.1% of children with persistent wheezing (p < 0.05).

CONCLUSION

Persistent wheezing, but not early transient wheezing seems to be a risk factor in the development of allergic rhinitis in children after five years of age.

Adolescent asthma after rhinovirus and respiratory syncytial virus bronchiolitis

BACKGROUND AND AIMS

Asthma risk is increased after bronchiolitis in infancy. Recent studies have suggested that the risk may be dependent on the causative virus. The aim of the study was to evaluate the asthma risk in adolescence in subjects hospitalized for rhinovirus or respiratory syncytial virus (RSV) bronchiolitis in infancy.

SUBJECTS AND METHODS

At the median age of 16.5 years, a questionnaire was sent to 96 study subjects hospitalized for bronchiolitis at <24 months of age and since then prospectively followed-up. Sixty-seven (70%) returned the fulfilled questionnaire. RSV and rhinovirus etiology of bronchiolitis had been studied in serum and respiratory samples obtained on admission in infancy. The occurrence of asthma was compared between former bronchiolitis patients and population controls recruited for this study in adolescence.

RESULTS

Doctor-diagnosed asthma was present in 30% of former bronchiolitis patients and in 5% of controls (OR 7.9, 95% CI 3.3-19.3). The respective figures for self-reported asthma were 64% and 11% (OR 14.7, 95% CI 7.2-30.0). Self-reported asthma was more common in the former rhinovirus than RSV patients (83.3% vs. 47.6%, P = 0.023, mixed infections included; 81.3% vs. 50%, P = 0.067, mixed infections excluded).

CONCLUSIONS

Patients hospitalized for RSV and rhinovirus bronchiolitis at <24 months of age had an increased asthma risk at 15-18 years of age compared with population controls. Within the former bronchiolitis group, the risk of self-reported asthma was higher after non-RSV versus RSV and after rhinovirus versus non-rhinovirus bronchiolitis.

Immunogenicity and safety of an inactivated trivalent split influenza virus vaccine in young children with recurrent wheezing

Influenza virus vaccination is recommended for children, but so far, active vaccination has not been achieved because most parents lack knowledge of vaccine safety and many doctors are reluctant to administer vaccine due to concerns that steroids might alter immunogenicity. The aim of this study was to compare the immunogenicity and safety of inactivated trivalent split influenza virus vaccine between children with recurrent wheezing and healthy children of the same age group. Sixty-eight healthy children and 62 children with recurrent wheezing took part in this study. Seroconversion rates, seroprotection rates, geometric mean titers (GMTs), and geometric mean titer ratios (GMTRs) were measured by a hemagglutination inhibition assay for the assessment of immunogenicity. Solicited and unsolicited local and systemic adverse events were measured for the assessment of safety. Regarding immunogenicity, the seroconversion and seroprotection rates showed no difference overall between healthy children and children with recurrent wheezing. Also, no difference was observed between steroid-treated and nontreated groups with recurrent wheezing. Generally, the GMTs after vaccination were higher in the one-dose vaccination groups for healthy children and children with recurrent wheezing, but the GMTRs revealed different results according to strain in the two groups. Regarding safety, solicited local and systemic adverse events showed no differences between healthy children and children with recurrent wheezing. This study demonstrates that inactivated split influenza virus vaccine is able to induce protective immune responses in healthy children, as observed in previous studies, as well as in children with recurrent wheezing who require frequent steroid treatment.

Oxygen dose responsiveness of human fetal airway smooth muscle cells

Maintenance of blood oxygen saturation dictates supplemental oxygen administration to premature infants, but hyperoxia predisposes survivors to respiratory diseases such as asthma. Although much research has focused on oxygen effects on alveoli in the setting of bronchopulmonary dysplasia, the mechanisms by which oxygen affects airway structure or function relevant to asthma are still under investigation. We used isolated human fetal airway smooth muscle (fASM) cells from 18-20 postconceptual age lungs (canalicular stage) to examine oxygen effects on intracellular Ca(2+) ([Ca(2+)](i)) and cellular proliferation. fASM cells expressed substantial smooth muscle actin and myosin and several Ca(2+) regulatory proteins but not fibroblast or epithelial markers, profiles qualitatively comparable to adult human ASM. Fluorescence Ca(2+) imaging showed robust [Ca(2+)](i) responses to 1 μM acetylcholine (ACh) and 10 μM histamine (albeit smaller and slower than adult ASM), partly sensitive to zero extracellular Ca(2+). Compared with adult, fASM showed greater baseline proliferation. Based on this validation, we assessed fASM responses to 10% hypoxia through 90% hyperoxia and found enhanced proliferation at <60% oxygen but increased apoptosis at >60%, effects accompanied by appropriate changes in proliferative vs. apoptotic markers and enhanced mitochondrial fission at >60% oxygen. [Ca(2+)](i) responses to ACh were enhanced for <60% but blunted at >60% oxygen. These results suggest that hyperoxia has dose-dependent effects on structure and function of developing ASM, which could have consequences for airway diseases of childhood. Thus detrimental effects on ASM should be an additional consideration in assessing risks of supplemental oxygen in prematurity.

Vaccination coverage and risk factors for incomplete vaccination in children with recurrent wheeze

AIM

To determine the possible impact of recurrent wheeze on immunisation status in the first three years of life.

METHOD

A cross-sectional case control study of 288 children less than three years of age with a history of recurrent wheezing, hospitalised at a single centre for wheeze; and a control group of 190 children with no prior history of wheezing. Vaccination charts of all children were analysed according to the National Immunisation Schedule. Additionally, some associated data were collected through a questionnaire to the parents.

RESULTS

Children with recurrent wheezing during the first three years of life were less likely to be vaccinated against BCG (Bacillus-Calmette-Guerin), hepatitis B, Hib (Haemophilus influenza type B), and MMR (Measles, Mumps, Rubella) (p < 0.001). A significant inverse association was also found between the number of wheezy episodes and the number of vaccine doses received. The odds ratio of incomplete vaccination in children with recurrent wheeze was 10.6 (95% CI, 2.96 to 38.1).

CONCLUSION

Children under three years of age with recurrent wheeze run a high risk of incomplete immunisation. Efforts should be therefore made to insure that such children receive adequate vaccination.

Bacterial infections and pediatric asthma

Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis seem to have no role in asthma in children. Mycoplasma pneumoniae and Chlamydophila pneumoniae can induce wheezing and cause asthma exacerbations in children, and chronic Chlamydophila infections may even participate in asthma pathogenesis. However, studies have failed to show any benefits from antibiotics for incipient or stable pediatric asthma, as well as for asthma exacerbations in children. Exposure to antibiotics in infancy has been an independent risk factor of later asthma in many studies. A recent study applying molecular biology methods to lower airway samples provided preliminary evidence that lower airways are not sterile but have their own protective microbiota, which can be disturbed in lung diseases like asthma.

Diagnosis of allergy and asthma in childhood

Childhood asthma is a widespread health problem because of its epidemic prevalence, as asthma affects more than 300 million people worldwide. Results from cross-sectional and cohort studies show that asthma starts in childhood in a large proportion of cases. A proper diagnosis is easier to make in adults and school-age children, as permanent changes in lung development, the strong impact of environmental factors on the airways, the immunologic maturity process, and the use of some diagnostic tools make asthma more difficult to diagnose in preschool children. This period of a child's life is an interesting challenge for pediatricians and specialists. The aim of the present review is to analyze the current knowledge regarding making an early and accurate asthma diagnosis and therefore deciding on the correct treatment to gain control over asthma symptoms and minimize health risks.

Interaction between early maternal smoking and variants in TNF and GSTP1 in childhood wheezing

BACKGROUND

Children exposed to tobacco smoke early in life have a higher risk of wheeze. Individual susceptibility may depend on genetic factors.

OBJECTIVE

We studied whether variations in single nucleotide polymorphisms (SNPs) in the TNF, glutathione S transferase P1 (GSTP1) and beta2-adrenoreceptor (ADRB2) genes modify the effect of early maternal smoking on the development of childhood asthma, wheeze and allergic sensitization.

METHODS

In the Swedish prospective birth cohort BAMSE (Children, Allergy, Milieu, Stockholm, Epidemiological Survey) (n=4089), data collection included questionnaires to measure tobacco smoke exposure and clinical outcomes up to age 4 and medical examinations with blood sampling for specific IgE measurements and genotyping. We defined early maternal smoking as daily smoking by the mother during pregnancy and/or postnatally. We investigated five TNF, six GSTP1 and three ADRB2 SNPs in 982 selected wheezers and non-wheezers.

RESULTS

An interaction with early maternal smoking was found for three TNF SNPs (-857C/T, Intron 1, Intron 3) with respect to early wheeze (up to 2 years of age). For example, the odds ratio (OR) for developing early wheeze related to early maternal smoking was 2.4 [95% confidence interval (CI) 1.6-3.7] in children with a wild-type CC homozygote genotype of the TNF-857 SNP, while no tobacco-related risk was seen in children carrying the rare T allele. A clear dose response was observed in children with the CC genotype, with an OR of 1.3 (95% CI 1.1-1.5) per each additional pack per week smoked by the mother during pregnancy. A suggestive interaction with early maternal smoking was also seen for three GSTP1 SNPs (Intron 5, Intron 6 and Ile105Val) with respect to transient wheeze, but not for ADRB2 and wheeze phenotypes. No effect modifications were observed for allergic sensitization.

CONCLUSION

Our results suggest that the risk of early childhood wheeze associated with early maternal smoking may be modified by TNF and GSTP1 polymorphisms.

Adulthood asthma after wheezing in infancy: a questionnaire study at 27 years of age

BACKGROUND

Wheezing in early childhood is a heterogeneous condition, the longterm prognosis varying from total recovery to chronic asthma. Though short-term outcome has been actively studied, there is lack of data on long-term outcome until adulthood. The aim of the study was to evaluate the prevalence and risk factors of asthma at 26-29 years of age after early-life wheezing.

METHODS

At the median age of 27.3 years (range 26.3-28.6), a questionnaire was sent to 78 study subjects hospitalized for wheezing at <24 months of age, and 59 (76%) answered. Asthma, allergy and weight status were compared with selected controls followed up from birth and with non-selected population controls recruited for this adulthood study.

RESULTS

Doctor-diagnosed asthma was present in 20% of the former bronchiolitis patients, compared with 5% in the two control groups (OR 2.1, 95% CI 0.3-17.9 vs selected controls; OR 5.2, 95% CI 1.7-15.8 vs nonselected controls). The respective figures for current self-reported asthma were 41% and 7-10% (OR 11.4, 95% CI 2.3-56.1 vs selected controls; OR 12.2, 95% CI 4.4-33.7 vs nonselected controls). Current allergic rhinitis and current smoking were significantly associated with asthma, but current overweight or obesity was not. In multivariate analyses, early-life wheezing was an independent risk factor of adulthood asthma.

CONCLUSION

An increased asthma risk in early-life wheezers continues, even after many symptom-free years at school age, at least until 27 years of age.

Benign joint hypermobility syndrome: a cause of childhood asthma?

Benign joint hypermobility syndrome (BJHS) is a hereditable disorder of connective tissue, which is characterized by the occurrence of multiple musculoskeletal problems in hypermobile individuals who do not have a systemic rheumatological disease. Rectal, uterine and mitral prolapses, varicose veins, myopia and recurrent urinary tract infections are more common in patients with BJHS, which indicates a diffuse anomaly in the structure of connective tissue rather than a limited involvement of the musculoskeletal system. Asthma, as a complex trait disease, develops after environmental exposure to innocuous allergens, infectious agents and air pollutants in susceptible individuals on the basis of their genetics. However, genetic factors cannot explain the recent rise in the prevalence, morbidity, or mortality of asthma. Asthma may also be caused by a connective tissue defect. Changes in the mechanical properties of the bronchial airways and lung parenchyma may underlie the increased tendency of the airways to collapse in asthmatic children. In this paper, we postulate that BJHS may lead to persistent childhood wheezing by causing airway collapse through a connective tissue defect that affects the structure of the airways.

Is there a link between wheezing in early childhood and adverse birth outcomes? A systematic review

We aimed to provide a summary of the existing published knowledge on the association between adverse birth outcomes and the development of wheezing during the first two years of life. We carried out a systematic review of epidemiological studies within the MEDLINE database. Epidemiological studies on human subjects, published in English, were included in the review. A comprehensive literature search yielded 72 studies for further consideration. Following the application of the eligibility criteria we identified nine studies. A positive association and an excess risk of wheezing during the first two years of life were revealed for adverse birth outcomes.