Demographic and neonatal risk factors for childhood asthma in the USA

Perinatal, obstetric and parental risk factors for asthma in the offspring throughout childhood: a longitudinal cohort study

OBJECTIVES

Asthma is a common chronic and burdensome disease which typically begins in childhood. The aim of this study was to assess perinatal and obstetric factors which may increase the risk of developing asthma in the offspring.

METHODS

Data from five consecutive waves (n=7,073 children, from birth to 15 years old) from a nationally-representative birth cohort of people born in the United Kingdom between 2000 and 2002, the Millennium Cohort Study (MCS), were used. The Kaplan-Meier survival curve was used to graphically display the risk of developing asthma from early childhood to adolescence. The Z-based Wald test was used to prove significant covariate loading.

RESULTS

Cox regression analyzing the influence of covariates on asthma development risk showed a significant likelihood ratio test, χ2(18)=899.30, p<0.01. A parent with asthma (OR=2.02, p<0.01), a younger maternal age at delivery (OR=0.98, p<0.05), and the use of assisted reproductive technology (OR=1.43, p<0.05) were associated with an increased risk of developing asthma in the offspring.

CONCLUSIONS

Perinatal factors (a younger maternal age, assisted reproductive technology) and a parental factor (a parent with asthma) increased the risk for developing asthma in the offspring.

Upregulated antimicrobial immune response mediated by neutrophils in the development from allergic rhinitis to asthma

Background

Allergic rhinitis (AR) and asthma are closely related, and AR is regarded as an important risk factor for the onset of asthma. However, the pathogenesis of the development of asthma from AR is still undefined.

Objective

The aim of this study was to investigate the mechanisms underlying the development of asthma from AR by comparing the transcriptome features of patients with AR with and without asthma.

Methods

Patients with AR with or without asthma caused by weed pollen who presented to the Allergy Clinic of Peking Union Medical College Hospital were recruited for this study. Peripheral blood samples of all the patients were collected during the weed pollen season (September) when the patients had allergic symptoms and outside the pollen season (November) when the patients had no symptoms. Transcriptomic analysis was conducted, and the differentially expressed genes (DEGs) and enriched immune pathways between the patients with AR with asthma (AR-asthma group) and those without asthma (AR group) were identified. In addition, the expression levels of some pivotal differentially expressed RNAs were quantified using quantitative polymerase chain reaction (PCR).

Results

During the weed pollen season, the immune-related Gene Ontology (GO) terms with P value < 0.05, enriched by the upregulated genes in the AR-asthma group compared to the AR group included antifungal humoral response, neutrophil-mediated killing of bacterium, antibacterial humoral response, antimicrobial humoral immune response mediated by antimicrobial peptides, and regulation of the T cell receptor signaling pathway. The immune-related GO terms with P values <0.05 enriched by downregulated genes were positive regulation of natural killer cell-mediated cytotoxicity, microglial cell activation, natural killer cell activation, and leukocyte-mediated cytotoxicity. The GO term of antimicrobial humoral immune response mediated by antimicrobial peptides was upregulated both during and outside the pollen season, and the upregulated expression of three DEGs (LTF, PF4, and ELANE) included in this term was verified through quantitative PCR.

Conclusions

The activation of the antimicrobial immune response mediated by neutrophils and the depression of cytotoxicity mediated by natural killer cells may play roles in the progression from AR to asthma.

Reported asthma and dental amalgam exposure among adults in the United States: An assessment of the National Health and Nutrition Examination Survey

Objective: Mercury (Hg)-based amalgam is a dental restorative material in common use. This hypothesis-testing study evaluated the relationship between dental amalgam exposure and the risk of reported asthma diagnoses in American adults. Methods: A total of 97,861,577 weighted-persons with one or more dental amalgam surfaces (exposed group) and 31,716,558 weighted-persons with one or more other dental surfaces (no dental amalgams, unexposed group) were examined in the 2015–2016 National Health and Nutrition Examination Survey. All persons were 20–80 years old and with known reported asthma status (only newly diagnosed asthma cases were examined). Survey logistic regression and survey frequency modeling in SAS were employed to evaluate the relative incidence rate of reported asthma diagnoses among those in the exposed group compared to the unexposed group. Covariates of gender, race, socioeconomic status, educational status, country of birth, and tobacco exposure were considered. Results: Survey logistic modeling revealed a significantly increased incidence rate of reported asthma in the exposed group as compared to the unexposed group in unadjusted (4.46-fold) and adjusted (4.84-fold) models. A dose–response relationship was observed for the risk of reported asthma per dental amalgam filling surface in unadjusted (1.073) and adjusted (1.076) models. Survey frequency modeling revealed that the frequency of reported asthma (per 10,000 weighted-person years) was 3.66-fold significantly increased in the exposed group (2.06) as compared to the unexposed group (0.56). Conclusion: Increased dental amalgam exposure was associated with an increased risk of reported asthma diagnoses in American adults, but future studies should further evaluate this relationship.

Association analysis of the surfactant protein-C gene to childhood asthma

OBJECTIVES

This study aims to describe the molecular variability in the SFTPC gene in a childhood chronic respiratory disease, asthma, in the Tunisian population and to identify the implications based on a case-control study of p.Thr138Asn (T138N) and p.Ser186Asn (S186N) variants.

METHODS

We used direct sequencing for the genotyping of the SFTPC gene within 101 asthmatic children. The study of T138N and S186N variants in 110 controls is conducted by the PCR-RFLP technique.

RESULTS

The molecular study revealed 26 variants including 24 intronic variations and 2 exonic variations (T138N and S186N) with respective frequencies of 16.8% and 18.3%. We conducted a case-control study of the two identified exonic variations. A different genotypic and allelic distribution between the two groups was noted. Only the T138N polymorphism showed a significant association with asthma disease (p < 1 0 ^-3). Statistical analysis elaborated four haplotypes with the following frequencies in patients vs controls: 138Thr-186Ser (79.5% vs 57.6%), 138Thr-186Asn (3.7% vs 7.8%), 138Asn-186Thr (2.2% vs 20.2%) and 138Asn-186Asn (14.6% vs 14.4%). A significant difference (p < 1 0 ^-3) was highlighted in haplotype distribution. The 138Asn-186Ser (OR [95%CI] = 0.14[0.04-0.54], p = 0.004, R²=0.93) and 138Thr-186Asn (OR [95%CI] = 0.35[0.12-0.54], p = 0.047, R²=0.88) haplotypes showed a negative association with asthma which may constitute a protective factor against the disease.

CONCLUSION

In Tunisia, this work constitutes the first report interested in the SFTPC gene and highlights the genetic variability of the SFTPC gene in asthma. Therefore, the case-controls analysis may be useful in the study of surfactant proteins dysfunction in chronic respiratory disease at an early age.

Maternal Distress During Pregnancy and Recurrence in Early Childhood Predicts Atopic Dermatitis and Asthma in Childhood

BACKGROUND

Early-life stress is becoming an important determinant of immune system programming. Maternal prenatal distress is found to be associated with atopic disease in offspring but the separate effects of postnatal distress are not well-studied.

RESEARCH QUESTION

Does the likelihood of asthma and atopic dermatitis in children increase when they are exposed to maternal distress pre- and postnatally in a sex-specific manner?

STUDY DESIGN AND METHODS

Using data from a provincial newborn screen and health-care database for 12,587 children born in 2004, maternal distress (depression or anxiety) was defined as prenatal, self-limiting, recurrent, or late-onset postpartum. Atopic dermatitis (AD) and asthma at ages 5 years and 7 years of age were diagnosed by using hospitalization, physician visit, or prescription records. Associations between maternal distress and childhood asthma and AD were determined by using multiple logistic regression.

RESULTS

After adjusting for risk factors, a significant association between maternal prenatal (OR, 1.27; 95% CI, 1.11-1.46), recurrent postpartum (OR, 1.28; 95% CI, 1.11-1.48), and late-onset postpartum (OR, 1.19, 95% CI, 1.06-1.34) distress was found with AD at age 5 years. Asthma at age 7 years was also associated with maternal prenatal distress (OR, 1.57; 95% CI, 1.29-1.91) and late-onset postnatal distress (OR, 1.22; 95% CI, 1.01-1.46). Self-limiting postnatal distress was not found to be a risk factor for either atopic condition. Associations with AD or asthma were of a similar magnitude in boys and girls; the exception was recurrent postnatal distress, which increased risk for asthma in boys only.

INTERPRETATION

This population-based study provides evidence for sex-specific associations between maternal prenatal and postnatal distress, as well as the development of AD and asthma. The findings support recommendations for greater psychosocial support of mothers during pregnancy and early childhood to prevent childhood atopic disease.

A cross-sectional study of the relationship between reported human papillomavirus vaccine exposure and the incidence of reported asthma in the United States

Objectives:

Asthma is a chronic disorder that affects persons of all ages impacting the quality of their lives. This cross-sectional hypothesis-testing study evaluated the relationship between human papillomavirus vaccine and the risk of an incident asthma diagnosis in a defined temporal period post-vaccination.

Methods:

The 2015–2016 National Health and Nutrition Examination Survey data were examined for a group of 60,934,237 weighted persons between 9 and 26 years old in Statistical Analysis Software.

Results:

Reported incident asthma significantly clustered in the year of reported human papillomavirus vaccination. When the data were separated by gender, the effects observed remained significant for males but not females.

Conclusion:

The results suggest that human papillomavirus vaccination resulted in an excess of 261,475 asthma cases with an estimated direct excess lifetime cost of such persons being US$42 billion. However, it is unclear what part of the vaccine and/or vaccine medium may have increased an individual’s susceptibility to an asthma episode, whether the asthma diagnosis represented one asthma episode or if it is chronic, and how much therapeutic support was needed (if any) and for how long, which would impact cost. Despite the negative findings in this study, routine vaccination is an important public health tool, and the results observed need to be viewed in this context.

Sex-specific airway hyperreactivity and sex-specific transcriptome remodeling in neonatal piglets challenged with intra-airway acid

Acute airway acidification is a potent stimulus of sensory nerves and occurs commonly with gastroesophageal reflux disease, cystic fibrosis, and asthma. In infants and adults, airway acidification can acutely precipitate asthma-like symptoms, and treatment-resistant asthma can be associated with gastroesophageal reflux disease. Airway protective behaviors, such as mucus secretion and airway smooth muscle contraction, are often exaggerated in asthma. These behaviors are manifested through activation of neural circuits. In some populations, the neural response to acid might be particularly important. For example, the immune response in infants is relatively immature compared with adults. Infants also have a high frequency of gastroesophageal reflux. Thus, in the current study, we compared the transcriptomes of an airway-nervous system circuit (e.g., tracheal epithelia, nodose ganglia, and brain stem) in neonatal piglets challenged with intra-airway acid. We hypothesized that the identification of parallel changes in the transcriptomes of two neutrally connected tissues might reveal the circuit response, and, hence, molecules important for the manifestation of asthma-like features. Intra-airway acid induced airway hyperreactivity and airway obstruction in male piglets. In contrast, female piglets displayed airway obstruction without airway hyperreactivity. Pairwise comparisons revealed parallel changes in genes directly implicated in airway hyperreactivity ( scn10a) in male acid-challenged piglets, whereas acid-challenged females exhibited parallel changes in genes associated with mild asthma ( stat 1 and isg15). These findings reveal sex-specific responses to acute airway acidification and highlight distinct molecules within a neural circuit that might be critical for the manifestation of asthma-like symptoms in pediatric populations.

Sex Differences in Vulnerability to Prenatal Stress: a Review of the Recent Literature

PURPOSE OF REVIEW

To evaluate the degree to which recent studies provide evidence that the effects of prenatal maternal stress (PNMS) on child health outcomes vary depending on the child's biological sex. In this review, we used a broad definition of stress, including negative life events, psychological stress, and established stress biomarkers. We identified 50 peer-reviewed articles (published January 2015-December 2017) meeting the inclusion criteria.

RECENT FINDINGS

Most articles (k = 35) found evidence of either sex-specific associations (significant in one sex but not the other) or significant PNMSxstress interactions for at least one child health outcome. Evidence for sex-dependent effects was strongest in the group of studies evaluating child neural/nervous system development and temperament as outcomes. There is sufficient evidence of sex-dependent associations to recommend that researchers always consider the potential role of child sex in PNMS programming studies and report descriptive statistics for study outcomes stratified by child biological sex.

A new model of wheezing severity in young children using the validated ISAAC wheezing module: A latent variable approach with validation in independent cohorts

BACKGROUND

The International Study of Asthma and Allergies in Children (ISAAC) Wheezing Module is commonly used to characterize pediatric asthma in epidemiological studies, including nearly all airway cohorts participating in the Environmental Influences on Child Health Outcomes (ECHO) consortium. However, there is no consensus model for operationalizing wheezing severity with this instrument in explanatory research studies. Severity is typically measured using coarsely-defined categorical variables, reducing power and potentially underestimating etiological associations. More precise measurement approaches could improve testing of etiological theories of wheezing illness.

METHODS

We evaluated a continuous latent variable model of pediatric wheezing severity based on four ISAAC Wheezing Module items. Analyses included subgroups of children from three independent cohorts whose parents reported past wheezing: infants ages 0-2 in the INSPIRE birth cohort study (Cohort 1; n = 657), 6-7-year-old North American children from Phase One of the ISAAC study (Cohort 2; n = 2,765), and 5-6-year-old children in the EHAAS birth cohort study (Cohort 3; n = 102). Models were estimated using structural equation modeling.

RESULTS

In all cohorts, covariance patterns implied by the latent variable model were consistent with the observed data, as indicated by non-significant χ2 goodness of fit tests (no evidence of model misspecification). Cohort 1 analyses showed that the latent factor structure was stable across time points and child sexes. In both cohorts 1 and 3, the latent wheezing severity variable was prospectively associated with wheeze-related clinical outcomes, including physician asthma diagnosis, acute corticosteroid use, and wheeze-related outpatient medical visits when adjusting for confounders.

CONCLUSION

We developed an easily applicable continuous latent variable model of pediatric wheezing severity based on items from the well-validated ISAAC Wheezing Module. This model prospectively associates with asthma morbidity, as demonstrated in two ECHO birth cohort studies, and provides a more statistically powerful method of testing etiologic hypotheses of childhood wheezing illness and asthma.

Treatment of Allergic Rhinitis as a Strategy for Preventing Asthma

PURPOSE OF REVIEW

To evaluate the impact of allergic rhinitis (AR) on the development of asthma and to update readers on recent literature suggesting that early treatment of allergic subjects with immunotherapy may prevent asthma onset.

RECENT FINDINGS

AR is frequently associated with asthma, leading to the concept that these two conditions are different aspects of the same disease. There is increasing evidence that AR precedes the onset of asthmatic symptoms and current treatment strategies are beneficial in symptom control with no impact prevention. There is limited knowledge about the risk factors responsible for the progression of AR to asthma, though recent data supports the notion that it is possible to prevent asthma onset by allergen immunotherapy. Despite significant advances in specific immunotherapy (SIT) therapy strengthening its efficacy in AR and possible prevention of progression to asthma, the adoption of this therapeutic strategy is still restricted in comparison to therapies directed towards treatment of AR symptoms. Unlike corticosteroids and other symptomatic therapies, the benefit of SIT treatment in allergic individuals has been shown to prevent the development of allergic conditions. Hence, large well-conducted randomized clinical trials with long-term efficacy of SIT are required to confirm or refute the concept that SIT may abrogate the progression of AR to asthma in patients.