Relationships among Maternal Stress and Depression, Type 2 Responses, and Recurrent Wheezing at Age 3 Years in Low-Income Urban Families

Viral and non-viral episodes of wheezing in early life and the development of asthma and respiratory phenotypes among urban children

BACKGROUND

Viral wheezing is an important risk factor for asthma, which comprises several respiratory phenotypes. We sought to understand if the etiology of early-life wheezing illnesses relates to childhood respiratory and asthma phenotypes.

METHODS

Data were collected prospectively on 429 children in the Urban Environment and Childhood Asthma (URECA) birth cohort study through age 10 years. We identified wheezing illnesses and the corresponding viral etiology (PCR testing of nasal mucus) during the first 3 years of life. Six phenotypes of respiratory health were identified at 10 years of age based on trajectories of wheezing, allergic sensitization, and lung function. We compared the etiology of early wheezing illnesses to these wheezing respiratory phenotypes and the development of asthma.

RESULTS

In the first 3 years of life, at least one virus was detected in 324 (67%) of the 483 wheezing episodes documented in the study cohort. Using hierarchical partitioning we found that non-viral wheezing episodes accounted for the greatest variance in asthma diagnosed at both 7 and 10 years of age (8.0% and 5.8% respectively). Rhinovirus wheezing illnesses explained the most variance in respiratory phenotype outcome followed by non-viral wheezing episodes (4.9% and 3.9% respectively) at 10 years of age.

CONCLUSION AND RELEVANCE

Within this high-risk urban-residing cohort in early life, non-viral wheezing episodes were frequently identified and associated with asthma development. Though rhinovirus wheezing illnesses had the greatest association with phenotype outcome, the specific etiology of wheezing episodes in early life provided limited information about subsequent wheezing phenotypes.

Postpartum Maternal Anxiety Affects the Development of Food Allergy Through Dietary and Gut Microbial Diversity During Early Infancy

PURPOSE

We aimed to investigate the mediating factors between maternal anxiety and the development of food allergy (FA) in children until 2 years from birth.

METHODS

In this longitudinal cohort of 122 mother-child dyads from pregnancy to 24 months of age, we regularly surveyed maternal psychological states, infant feeding data, and allergic symptoms and collected stool samples at 6 months of age for microbiome analysis. Considering the temporal order of data collection, we investigated serial mediating effects and indirect effects among maternal anxiety, dietary diversity (DD), gut microbial diversity, and FA using structural equation modeling.

RESULTS

Among the 122 infants, 15 (12.3%) were diagnosed with FA. Increased maternal anxiety between 3 and 6 months after delivery was associated with a lower DD score. Infants with low DD at 4 months showed low gut microbial richness, which was associated with FA development. When the infants were grouped into 4 subtypes, using consensus clustering of 13 gut bacteria significantly associated with maternal anxiety and DD, Prevotella, Eubacterium, Clostridiales and Lachnospiraceae were more abundant in the group with lower FA occurrence.

CONCLUSIONS

Postpartum maternal anxiety, mediated by reduced DD and gut microbial diversity, may be a risk factor for the development of FA in infants during the first 2 years of life.

Parental Mental Health and Childhood Respiratory Outcomes in a Severe Bronchiolitis Cohort

Parental mental health conditions appear to contribute to the development of childhood respiratory illness. We investigated the relationship between parental mental health and childhood respiratory illness using data from a 17-center prospective cohort study of infants hospitalized with bronchiolitis between 2011 and 2014 (n = 921). Among 779 (84.6%) participants with self-reported parental mental health history data, 184 (23.6%) had parental history of depression and 155 (19.9%) had anxiety. Multivariable analyses found that both parental history of depression (hazard ratio [HR] 1.41, 95% confidence interval [CI] 1.01-1.99) and anxiety (HR 1.28, 95% CI 1.08-1.52) were associated with an increased risk of recurrent wheezing by age 3 years. However, only parental history of anxiety was associated with asthma by age 5 years (odds ratio 1.79, 95% CI 1.25-2.55). Further research on exposure severity, other early life stressors, and effective methods of parental psychosocial support is needed to develop targeted risk factor prevention strategies to reduce the burden of childhood respiratory illness.

Social determinants of health influence preschool and caregiver experiences during symptoms and exacerbations of wheezing

BACKGROUND

Social determinants of health have been inadequately studied in preschool children with wheezing and their caregivers but may influence the care received.

OBJECTIVE

To evaluate the symptom and exacerbation experiences of wheezing preschool children and their caregivers, stratified by risk of social vulnerability, over 1 year of longitudinal follow-up.

METHODS

A total of 79 caregivers and their preschool children with recurrent wheezing and at least 1 exacerbation in the previous year were stratified by a composite measure of social vulnerability into "low" (N = 19), "intermediate" (N = 27), and "high" (N = 33) risk groups. Outcome measures at the follow-up visits included child respiratory symptom scores, asthma control, caregiver-reported outcome measures of mental and social health, exacerbations, and health care utilization. The severity of exacerbations reflected by symptom scores and albuterol use and exacerbation-related caregiver quality of life were also assessed.

RESULTS

Preschool children at high risk of social vulnerability had greater day-to-day symptom severity and more severe symptoms during acute exacerbations. High-risk caregivers were also distinguished by lower general life satisfaction at all visits and lower global and emotional quality of life during acute exacerbations which did not improve with exacerbation resolution. Rates of exacerbation or emergency department visits did not differ, but intermediate- and high-risk families were significantly less likely to seek unscheduled outpatient care.

CONCLUSION

Social determinants of health influence wheezing outcomes in preschool children and their caregivers. These findings argue for routine assessment of social determinants of health during medical encounters and tailored interventions in high-risk families to promote health equity and improve respiratory outcomes.

Poorer Caregiver Mental and Social Health Is Associated With Worse Respiratory Outcomes in Preschool Children With Recurrent Wheezing

BACKGROUND

Mental and social health in caregivers of preschool children has been inadequately studied, but it may influence respiratory symptom recognition and management.

OBJECTIVE

To identify preschool caregivers at highest risk for poor mental and social health outcomes on the basis of patient-reported outcome measures.

METHODS

Female caregivers 18 to 50 years old (N = 129) with a preschool child aged 12 to 59 months with recurrent wheezing and at least 1 exacerbation in the previous year completed 8 validated patient-reported outcome measures of mental and social health. k-means cluster analysis was performed using the T score for each instrument. Caregiver/child dyads were followed for 6 months. Primary outcomes included caregiver quality of life and wheezing episodes in their preschool children.

RESULTS

Three clusters of caregivers were identified: low risk (n = 38), moderate risk (n = 56), and high risk (n = 35). The high-risk cluster had the lowest life satisfaction, meaning and purpose, and emotional support and the highest social isolation, depression, anger, perceived stress, and anxiety that persisted for more than 6 months. This cluster had the poorest quality of life and marked disparities in social determinants of health. Preschool children from caregivers in the high-risk cluster had more frequent respiratory symptoms and a higher occurrence of any wheezing episode, but a lower outpatient physician utilization for wheezing management.

CONCLUSIONS

Caregiver mental and social health is associated with respiratory outcomes in preschool children. Routine assessment of mental and social health in caregivers is warranted to promote health equity and improve wheezing outcomes in preschool children.

Early childhood wheezing phenotypes and determinants in a South African birth cohort: longitudinal analysis of the Drakenstein Child Health Study

BACKGROUND

Developmental trajectories of childhood wheezing in low-income and middle-income countries (LMICs) have not been well described. We aimed to derive longitudinal wheeze phenotypes from birth to 5 years in a South African birth cohort and compare those with phenotypes derived from a UK cohort.

METHODS

We used data from the Drakenstein Child Health Study (DCHS), a longitudinal birth cohort study in a peri-urban area outside Cape Town, South Africa. Pregnant women (aged ≥18 years) were enrolled during their second trimester at two public health clinics. We followed up children from birth to 5 years to derive six multidimensional indicators of wheezing (including duration, temporal sequencing, persistence, and recurrence) and applied Partition Around Medoids clustering to derive wheeze phenotypes. We compared phenotypes with a UK cohort (the Avon Longitudinal Study of Parents and Children [ALSPAC]). We investigated associations of phenotypes with early-life exposures, including all-cause lower respiratory tract infection (LRTI) and virus-specific LRTI (respiratory syncytial virus, rhinovirus, adenovirus, influenza, and parainfluenza virus) up to age 5 years. We investigated the association of phenotypes with lung function at 6 weeks and 5 years.

FINDINGS

Between March 5, 2012, and March 31, 2015, we enrolled 1137 mothers and there were 1143 livebirths. Four wheeze phenotypes were identified among 950 children with complete data: never (480 children [50%]), early transient (215 children [23%]), late onset (104 children [11%]), and recurrent (151 children [16%]). Multivariate adjusted analysis indicated that LRTI and respiratory syncytial virus-LRTI, but not other respiratory viruses, were associated with increased risk of recurrent wheeze (odds ratio [OR] 2·79 [95% CI 2·05-3·81] for all LTRIs; OR 2·59 [1·30-5·15] for respiratory syncytial virus-LRTIs). Maternal smoking (1·88 [1·12-3·02]), higher socioeconomic status (2·46 [1·23-4·91]), intimate partner violence (2·01 [1·23-3·29]), and male sex (2·47 [1·50-4·04]) were also associated with recurrent wheeze. LRTI and respiratory syncytial virus-LRTI were also associated with early transient and late onset clusters. Wheezing illness architecture differed between DCHS and ALSPAC; children included in ALSPAC in the early transient cluster wheezed for a longer period before remission and late-onset wheezing started at an older age, and no persistent phenotype was identified in DCHS. At 5 years, airway resistance was higher in children with early or recurrent wheeze compared with children who had never wheezed. Airway resistance increased from 6 weeks to 5 years among children with recurrent wheeze.

INTERPRETATION

Effective strategies to reduce maternal smoking and psychosocial stressors and new preventive interventions for respiratory syncytial virus are urgently needed to optimise child health in LMICs.

FUNDING

UK Medical Research Council; The Bill & Melinda Gates Foundation; National Institutes of Health Human Heredity and Health in Africa; South African Medical Research Council; Wellcome Trust.

Maternal affective and stress-related factors during pregnancy affect the occurrence of childhood allergic diseases: A Shanghai MCPC study

OBJECTIVE

To investigate the association between exposures to maternal affective and stress-related factors during pregnancy and allergies in children from birth to 2 years of age.

METHODS

We enrolled a total of 4178 children from the Shanghai Maternal-Child Pairs Cohort and measured maternal stress, anxiety, and depression during pregnancy by applying the Life Events Scale for Pregnant Women, Self-Rating Anxiety Scale, and the Center for Epidemiologic Studies-Depression Scale, respectively. Children's allergies were assessed by community physicians at 2, 6, 12, and 24 months, respectively; these included eczema, atopic dermatitis, food allergy, wheezing, asthma, and atopic rhinitis. We applied a latent class analysis (LCA) to these factors and analyzed the impacts of maternal affective and stress-related factors on childhood allergies by exploiting multivariate logistic regression.

RESULTS

Three distinct classes of children were revealed by LCA: healthy (79.8%), transient allergy (15.2%), and persistent allergy (4.9%). High maternal stress in both early and late pregnancy was associated with an increased risk of infant eczema at 2 months (aOR = 1.30, 95% CI = 1.01-1.67; aOR = 1.64, 95% CI = 1.14-2.36). Moreover, high maternal stress in late pregnancy was also associated with food allergy at 6 months, rhinitis at 2 years of age, and persistent allergy (aOR = 3.22, 95% CI = 1.27-8.12; aOR = 1.78, 95% CI = 1.01-3.15; and aOR = 1.93, 95% CI = 1.10-3.40).

CONCLUSIONS

The associations of maternal affective and stress-related factors during pregnancy with childhood allergies may vary by type and disease onset. We postulate that maternal stress in late pregnancy may exert a sustained negative effect on early childhood allergic diseases.

Brain-Airway Interactions in Asthma

Asthma and brain interactions have long been appreciated and initially centered on increased anxiety and depression. Epidemiology studies have shown that early life stressors and situational disadvantages are risk factors for asthma. Conversely, the presence of asthma is a risk for mood and anxiety disorders, thus indicating a bidirectional effect between asthma and brain-related health. To substantiate asthma-brain interactions, validated instruments indicate and elucidate that communication likely exists between asthma and the brain. For example, provocation of an asthmatic response with an allergen challenge modulates how the brain responds to emotion-laden information. As detected by imaging studies, emotion-related brain activation is associated with generating airway inflammation. However, the specific mediators and processes mediating airway communication with the brain have yet to be established.Systemic inflammation is also associated with asthma and can affect other organ systems such as the cardiovascular system and the brain. Epidemiology studies have shown that asthma is a risk factor for dementia and Alzheimer's disease. In support of the importance of asthma as a risk factor for impaired cognitive function, imaging studies have shown changes to the white matter of the brain in asthma patients that resemble neuroinflammation changes seen in Alzheimer's disease and other neurodegenerative diseases. Therefore, bidirectional links between asthma and the brain exist with an important next research step to define asthma-brain interactions linked to neurodegeneration and dementia and explore whether treatments directed toward asthma-related inflammation can prevent the deleterious effects of asthma on brain health.

Cytokine expression in rhinovirus- vs. respiratory syncytial virus-induced first wheezing episode and its relation to clinical course

Rhinovirus (RV) and respiratory syncytial virus (RSV) are common causes of bronchiolitis. Unlike an RSV etiology, an RV etiology is associated with a markedly increased risk of asthma. We investigated the cytokine profiles of RV- and RSV-induced first wheezing episode and their correlation with prognosis. We recruited 52 sole RV- and 11 sole RSV-affected children with a severe first wheezing episode. Peripheral blood mononuclear cells (PBMCs) were isolated during acute illness and 2 weeks later and stimulated in vitro with anti-CD3/anti-CD28. Culture medium samples were analyzed for 56 different cytokines by multiplex ELISA. Recurrences were prospectively followed for 4 years. In adjusted analyses, the cytokine response from PBMCs in the RV group was characterized by decreased expression of interleukin 1 receptor antagonist (IL-1RA), interleukin 1 beta (IL-1β), and monocyte chemoattractant protein-1 (MCP-1) and increased expression of eosinophil chemotactic protein 2 (eotaxin-2), thymus- and activation-regulated chemokine (TARC), and epithelial-derived neutrophil-activating peptide 78 (ENA-78) in the acute phase and increased expression of fractalkine in the convalescent phase compared to those in the RSV group. An analysis of the change in cytokine expression between study points revealed an increased expression of fractalkine and IL-1β and decreased expression of I-309 (CCL1) and TARC in the RV group compared to those in the RSV group.. Considering hospitalization time, a significant non-adjusted group × cytokine interaction was observed in the levels of interferon gamma (IFN-γ), macrophage-derived chemokine (MDC), IL-1RA, and vascular endothelial growth factor (VEGF), indicating that a higher expression of cytokine was associated with shorter hospitalization time in the RSV group but not in the RV group. A significant interaction was also found in interleukin 6 (IL-6), but the cytokine response was not associated with hospitalization time in the RSV or RV group. In the RV group, increased expression of I-309 (CCL1) and TARC was associated with fewer relapses within 2 months, and decreased expression of interleukin 13 (IL-13) and increased expression of I-309 (CCL1) were associated with less relapses within 12 months. Differences in cytokine response from PBMCs were observed between RV- and RSV-induced first severe wheezing episode. Our findings also reveal new biomarkers for short- and medium-term prognosis in first-time wheezing children infected with RV or RSV.

Pediatric Inner-City Asthma

Inner-city children with asthma are known to have high disease mortality and morbidity. Frequently, asthma in this high-risk population is difficult to control and more severe in nature. Several factors, including socioeconomic hardship, ability to access to health care, adherence to medication, exposure to certain allergens, pollution, crowd environment, stress, and infections, play an important role in the pathophysiology of inner-city asthma. Comprehensive control of home allergens and exposure to tobacco smoke, the use of immune based therapies, and school-based asthma programs have shown promising results in asthma control in this population.

Adenotonsillectomy, bronchoscopy and bronchoalveolar lavage in the management of preschool children with severe asthma: pilot study

PURPOSE

This is a pilot study that describes the feasibility and clinical course of a cohort of preschool children with severe asthma undergoing a combined adenotonillectomy (TA), bronchoscopy (B), and bronchoalveolar lavage (BAL) procedure.

METHODS

A retrospective cohort study of preschool patients with severe asthma who underwent a combined TA-B-BAL procedure between 2012 and 2019. Subjects were treated at a tertiary care asthma clinic and had a diagnosis of preschool asthma according to the Canadian Thoracic Society Guidelines. Data on demographics, clinical characteristics, medication use, virology and microbiology from bronchoalveolar lavage, and asthma control questionnaires were collected. Variables were analyzed using paired t test.

RESULTS

Eighteen preschool subjects (mean age 3.19 ± 1.13 years) with severe asthma were identified through the asthma clinic. Patients treated with standard asthma care and a combined  TA-B-BAL procedure  experienced a decrease in the number of oral steroid courses (p = 0.017), emergency department visits (p = 0.03) and wheezing exacerbations (p = 0.026) following the procedure. Ten patients experienced clinically meaningful improvements in TRACK scores after the procedure (p < 0.001).

CONCLUSION

This pilot study provides early evidence that a combined TA-B-BAL procedure is feasible in preschool children with severe asthma and that the procedure may reduce asthma medication use and hospital visits.

Maternal psychiatric status and infant wheezing: The role of maternal hormones and cord blood cytokines

RATIONALE

Maternal psychosocial stress might be associated with development of allergic diseases in the offspring.

OBJECTIVES

To evaluate the association of maternal depression and anxiety with ever wheezing and recurrent wheezing among infants and to assess the role of maternal hypothalamo-pituatary-adrenal axis changes and fetal immune response in this association.

METHODS

This study encompasses two designs; cohort design was developed to evaluate the association of prenatal depression with development of wheezing in infants while nested case-control design was used to assess the role of maternal cortisol and tetranectin and cord blood interleukin 13 and interferon γ.

RESULTS

We enrolled 697 pregnant women. Elementary school graduate mother (odds ratio [OR] = 1.5, p = .06), maternal smoking during pregnancy (OR = 3.4, p = .001), familial history of asthma (OR = 2.7, p < .001) increased the risk of ever wheezing. Elementary school graduate mother (OR = 2.6, p = .002), maternal smoking during pregnancy (OR = 4.8, p < .001) and familial history of asthma (OR = 1.7, p = .01) increased the risk of recurrent wheezing. Maternal previous psychiatric disease, or Edinburgh Postnatal Depression Scale or Spielberger State-Trait Anxiety Inventory scores were not associated with wheezing. Maternal tetranectin levels were significantly higher among never wheezers compared to the ever wheezers (264.3 ± 274.8 vs. 201.6 ± 299.7, p = .04).

CONCLUSIONS

In conclusion, the major risk factors for ever wheezing and recurrent wheezing were maternal smoking, level of education and family history of asthma. However, maternal depression and anxiety were not determined as risk factors for wheezing. Maternal tetranectin carries potential as a biomarker for wheezing in the infant.

Maternal stress and depression are associated with respiratory phenotypes in urban children

BACKGROUND

Prenatal and early-life exposure to maternal stress and depression is linked to development of recurrent wheezing in young children.

OBJECTIVE

We sought to determine whether maternal stress and depression in early life are associated with nonatopic wheezing phenotype in urban children.

METHODS

The Urban Environment and Childhood Asthma Study examined a birth cohort of children at high risk for asthma in low-income neighborhoods. Prenatal and postnatal (through age 3 years) maternal stress and depression scores were compared with respiratory phenotypes through age 10 years (multinomial regression), self-reported colds (linear regression), and detection of respiratory viruses (Poisson regression).

RESULTS

Scores for maternal depression, and, to a lesser extent, maternal perceived stress, were positively related to multiple wheezing phenotypes. In particular, cumulative measures of maternal depression in the first 3 years were related to the moderate-wheeze-low-atopy phenotype (odds ratio, 1.13; [1.05, 1.21]; P < .01). Considering indicators of respiratory health that were used to identify the phenotypes, there were multiple positive associations between early-life scores for maternal stress and depression and increased wheezing illnesses, but no consistent relationships with lung function and some inverse relationships with allergic sensitization. Cumulative maternal stress and depression scores were associated with cumulative number of respiratory illnesses through age 3 years.

CONCLUSIONS

Among high-risk, urban children, maternal stress and depression in early life were positively associated with respiratory illnesses and a moderate-wheeze-low-atopy phenotype. These results suggest that treating stress and depression in expectant and new mothers could reduce viral respiratory illnesses and recurrent wheeze during the preschool years and some forms of childhood asthma.

Maternal Stress During Pregnancy Predicts Infant Infectious and Noninfectious Illness

OBJECTIVES

To examine the association between prenatal stress and infant physical health in the first year of life within an understudied, racially and ethnically diverse, highly stressed community sample. We expected that greater stress exposure would predict higher rates of infant illness.

STUDY DESIGN

Low-income, racially/ethnically diverse, overweight women with low medical risk pregnancies were recruited (2011-2014) during pregnancy. Pregnancy Stressful Life Events were assessed retrospectively (mean, 11.88 months postpartum). Perceived stress was assessed twice during pregnancy (at a mean of 17.4 weeks and again at a mean of 25.6 weeks) and at 6 months postpartum. Women with live births (n = 202) were invited; 162 consented to the offspring study. Medical records from pediatric clinics and emergency departments for 148 infants were abstracted for counts of total infectious illnesses, total noninfectious illness, and diversity of illnesses over the first year of life.

RESULTS

The final analytic sample included 109 women (mean age, 28.08 years) and their infants. In covariate-adjusted negative binomial models, maternal perceptions of stress across pregnancy were positively associated with infant illness. Each 1-point increase in average stress was associated with a 38% increase in incidence of infant infections (Incidence rate ratio, 1.38; 95% CI, 1.01-1.88; P < .05), a 73% increase in noninfectious illness (IRR, 1.73; 95% CI, 1.34-2.23; P < .05), and a 53% increase in illness diversity (IRR, 1.53; 95% CI, 1.25, 1.88; P < .01); effect sizes were larger for perceived stress later in pregnancy. Stressful life events count and postnatal stress were not uniquely associated with illness.

CONCLUSIONS

In line with recommendations from the American Academy of Pediatrics to screen for maternal perinatal depression, screening and support for stress reduction during pregnancy may benefit both maternal and child health.

A worldwide charter for all children with asthma

Childhood asthma is a huge global health burden. The spectrum of disease, diagnosis, and management vary depending on where children live in the world and how their community can care for them. Global improvement in diagnosis and management has been unsatisfactory, despite ever more evidence-based guidelines. Guidelines alone are insufficient and need supplementing by government support, changes in policy, access to diagnosis and effective therapy for all children, with research to improve implementation. We propose a worldwide charter for all children with asthma, a roadmap to better education and training which can be adapted for local use. It includes access to effective basic asthma medications. It is not about new expensive medications and biologics as much can be achieved without these. If implemented carefully, the overall cost of care is likely to fall and the global future health and life chance of children with asthma will greatly improve. The key to success will be community involvement together with the local and national development of asthma champions. We call on governments, institutions, and healthcare services to support its implementation.

Early life adversity exposure and circulating markers of inflammation in children and adolescents: A systematic review and meta-analysis

This study provides a comprehensive review of the published research on the association between early life adversity and markers of inflammation in children and adolescents. We conducted a systematic review of the published literature on the association between early life adversity and markers of inflammation in pediatric populations. To date, 27 studies have been published in this area representing a wide range of global populations and diverse methods of which nearly half were prospective, longitudinal studies. Of these 27, only 12 studies shared an inflammatory outcome with 4 or more other studies; 9 for CRP, and 6 for IL-6. The association between early life adversity and both CRP, z = .07 [.04, .10], and IL-6, z = .17 [-.07, .42], were small and only significant for CRP although comparable in magnitude to the effects observed in adult samples. Descriptively, the association between early life adversity and CRP appeared to be stronger in studies conducted in infants and adolescents compared with middle childhood. There was minimal evidence of publication bias for studies measuring CRP, but evidence of publication bias for studies using IL-6. Eight studies have looked at the association between early life adversity and stimulated inflammatory cytokines in vitro, and both the methods and results of these studies were mixed; the majority observed exaggerated production of inflammatory cytokines despite mixed methodological approaches that make comparisons across studies difficult. In summary, the evidence supporting an association between early life adversity and inflammation in pediatric samples is limited so far by the number of studies and their heterogeneous methodological approaches. More research that is grounded in a developmental framework and informed by the complexity of the innate immune system is needed in this area.

Association between maternal psychological adversity and lung function in South African infants: A birth cohort study

OBJECTIVE

The association of perinatal psychological adversity (ie, stressors and distress) with infant lung function (ILF) and development is not well studied in Africa and elsewhere. We determined the association between maternal perinatal psychological adversity and ILF in African infants.

DESIGN

Prospective longitudinal follow up of the Drakenstein Child Health Study birth cohort.

PARTICIPANTS

Seven hundred and sixty-two infants aged 6 to 10 weeks and 485 infants who had data for both maternal perinatal psychological adversity and ILF (measured at 6 to 10 weeks and 12 months).

METHODS

The main analyses were based on cross-sectional measures of ILF at each assessment (6 to 10 weeks or 12 months), using generalized linear models, and then on the panel-data of both longitudinal ILF assessments, using generalised estimating equations, that allowed specification of the within-group correlation structure.

RESULTS

Prenatal intimate partner violence (IPV) exposure was associated with reduced respiratory resistance at 6 to 10 weeks (beta coefficient [β] = -.131, P = .023); postnatal IPV with reduced ratio of time to peak tidal expiratory flow over total expiratory time (tPTEF /tE ) at 12 months (β = -.206, P = .016); and prenatal depression with lower respiratory rate at 6 to 10 weeks (β = -.044, P = .032) and at 12 months (β = -.053, P = .021). Longitudinal analysis found an association of prenatal IPV with reduced tPTEF /tE (β = -.052, P < .0001); postnatal IPV with decreased functional residual capacity (FRC; β = -.086, P < .0001); prenatal posttraumatic stress disorder with increased FRC (β = .017, P < .0001); prenatal depression with increased FRC (β = .026, P < .0001) and postnatal depression with increased FRC (β = .021, P < .0001).

CONCLUSION

Screening for psychological adversity and understanding the mechanisms involved may help identify children at risk of altered lung development and inform approaches to treatment.

Maternal psychosocial risk factors and lower respiratory tract infection (LRTI) during infancy in a South African birth cohort

Objective

To investigate the association between maternal antenatal and/or postnatal psychosocial risk factors (including depression, psychological distress, alcohol abuse and intimate partner violence (IPV) and infant lower respiratory tract infection (LRTI) in a low- and middle-income-country (LMIC).

Study design

Pregnant women (n = 1137) enrolled in a South African birth cohort study, the Drakenstein Child Health Study (DCHS) were longitudinally assessed for psychosocial risk factors including depression, psychological distress, alcohol abuse and/or intimate partner violence (IPV). Infants were followed from birth until one year of age for the development of LRTI by active surveillance. Two outcomes were evaluated: any LRTI, and severe and/or hospitalised LRTI. Logistic regression was used to identify associations between individual maternal psychosocial risk factors and LRTI outcomes. Analyses stratified by age were also performed to determine which age groups related to infant LRTI were linked with maternal psychosocial risk factors.

Results

There were 606 LRTI episodes in 369 infants in the first year (crude incidence rate = 0.53 episodes per person-year, 95%CI: 0.50; 0.56); 31% (n = 186) of episodes were severe or hospitalised events. Maternal psychosocial risk factors were associated with LRTI and severe LRTI, particularly postnatal and long-term maternal psychological distress, antenatal maternal alcohol consumption, and postnatal maternal IPV. Age stratified analyses found that antenatal maternal alcohol consumption was associated with early infant LRTI, while antenatal maternal depression was linked with infant severe LRTI between 3 and 6 months of age, and postnatal maternal IPV was associated with early LRTI and severe forms of LRTI.

Conclusion

The associations between maternal psychosocial risk factors and infant LRTI highlight the potential value of screening for maternal psychosocial risk factors in clinical settings and developing targeted interventions. Such interventions may not only improve maternal well-being, but also help reduce the burden of infant LRTI in LMIC settings.

Inner-City Asthma in Childhood

The inner-city is a well-established and well-studied location that includes children at high risk for high asthma prevalence and morbidity. A number of intrinsic and extrinsic risk factors contribute to asthma in inner-city populations. This review seeks to explore these risk factors and evaluate how they contribute to increased asthma morbidity. Previous literature has identified risk factors such as race and ethnicity, prematurity, obesity, and exposure to aeroallergens and pollutants. Environmental and medical interventions aimed at individual risk factors and specific asthma phenotypes have contributed to improved outcomes in the inner-city children with asthma.

New Directions in Pediatric Asthma

Childhood asthma affects many children placing them at significant risk for health care utilization and school absences. Several new developments relevant to the field of pediatric asthma have occurred over the last 5 years; yet, there is much more to learn. It is poorly understood how to prevent the disease, optimally address environmental challenges, or effectively manage poor adherence. Moreover, it is not clear how to customize therapy by asthma phenotype, age group, high risk groups, or severity of disease. Highlights of advances in pediatric asthma are reviewed and multiple essential areas for further exploration and research are discussed.

Perinatal maternal mental health is associated with both infections and wheezing in early childhood

BACKGROUND

Wheezing and infections are common during infancy, and the role of early-life exposures in their development is still under investigation. We examined associations between maternal mental health in pregnancy and after delivery and subsequent offspring wheezing and infections.

METHODS

We studied 2314 mother-child pairs recruited in the Piccolipiù birth cohort (Italy) from 2011 to 2015. Maternal mental health was assessed in pregnancy and 12 months after delivery via the General Health Questionnaire-12 (GHQ-12). GHQ-12 Likert scores were collapsed into low (below the upper tercile) and high (above). Risk ratios (RR) and 95% confidence intervals (CI) between each combination of scores-during pregnancy and 1 year after delivery-and outcomes were computed by log-binomial regression models.

RESULTS

High scores both in pregnancy and after delivery, compared with low scores in both periods, were associated with wheezing (RR: 1.35; 95% CI: 1.08, 1.69), recurrent (≥2 episodes) wheezing (1.35; 0.99, 1.83), any and recurrent (≥4 episodes) upper respiratory infections (1.20; 1.04, 1.41, and 1.45; 1.07, 1.97, respectively), lower respiratory infections (1.31; 1.08, 1.61), and diarrhea (1.49; 1.23, 1.80). High scores either during pregnancy or 1 year after delivery only were less consistently associated with outcomes.

CONCLUSIONS

Maternal mental health problems extending from pregnancy to the first year after delivery are associated with development of both wheezing and infections. As wheezing is mostly triggered by infections, increased infection susceptibility could represent a possible common biologic mechanism. This study confirms the importance of early-life exposures on childhood health.

Pediatric Inner-City Asthma

Inner-city children with asthma are known to have high disease mortality and morbidity. Frequently, asthma in this high-risk population is difficult to control and more severe in nature. Several factors, including socioeconomic hardship, ability to access to health care, adherence to medication, exposure to certain allergens, pollution, crowd environment, stress, and infections, play an important role in the pathophysiology of inner-city asthma. Comprehensive control of home allergens and exposure to tobacco smoke, the use of immune based therapies, and school-based asthma programs have shown promising results in asthma control in this population.

Inner-City Asthma in Children

Asthma in inner-city children is often severe and difficult to control. Residence in poor and urban areas confers increased asthma morbidity even after adjusting for ethnicity, age, and gender. Higher exposure to household pests, such as cockroaches and mice, pollutants and tobacco smoke exposure, poverty, material hardship, poor-quality housing, differences in health care quality, medication compliance, and heath care access also contribute to increased asthma morbidity in this population. Since 1991, the National Institutes of Allergy and Infectious Diseases established research networks: the National Cooperative Inner-City Asthma Study (NCICAS), the Inner-City Asthma Study (ICAS), and the Inner-City Asthma Consortium (ICAC), to improve care for this at risk population. The most striking finding of the NCICAS is the link between asthma morbidity and the high incidence of allergen sensitization and exposure, particularly cockroach. The follow-up ICAS confirmed that reductions in household cockroach and dust mite were associated with reduction in the inner-city asthma morbidity. The ICAC studies have identified that omalizumab lowered fall inner-city asthma exacerbation rate; however, the relationship between inner-city asthma vs immune system dysfunction, respiratory tract infections, prenatal environment, and inner-city environment is still being investigated. Although challenging, certain interventions for inner-city asthma children have shown promising results. These interventions include family-based interventions such as partnering families with asthma-trained social workers, providing guidelines driven asthma care as well as assured access to controller medication, home-based interventions aim at elimination of indoor allergens and tobacco smoke exposure, school-based asthma programs, and computer/web-based asthma programs.

Prenatal Maternal Depression and Neonatal Immune Responses

OBJECTIVE

The aim of the study was to examine the association of lifetime maternal depression with regulation of immune responses in the infant, measured by cytokine levels and lymphocyte proliferation (LP) in cord blood mononuclear cells collected at delivery.

METHODS

We studied women recruited in early pregnancy into the Project Viva longitudinal cohort who had cord blood assayed after delivery (N = 463). Women reported about depressive symptoms in midpregnancy (Edinburgh Postnatal Depression Scale) and depression history by questionnaire. Immune responses were assayed by an index of LP, and concentrations of five cytokines (interleukin [IL]-6, IL-10, IL-13, tumor necrosis tumor necrosis factor factor α, and interferon γ) after incubation of cord blood mononuclear cells either in medium alone or stimulated with phytohemagglutinin (PHA), cockroach extract, or house dust mite extract. We examined associations of maternal depression with these sets of cytokine measures using multivariable linear or tobit regression analyses.

RESULTS

After adjustment for confounders (mother's age, race/ethnicity, education, household income, season of birth, and child sex), levels of IL-10 after stimulation with cockroach or dust mite allergen were lower in cord blood from ever versus never depressed women, and a similar trend was evident in IL-10 stimulated with PHA (percentage difference: cockroach extract = -41.4, p = .027; house dust mite extract = 1-36.0, p = .071; PHA = -24.2, p = .333). No significant differences were seen in levels of other cytokines or LP.

CONCLUSIONS

Maternal depression is associated with offspring immune responses at birth, which may have implications for later life atopic risk or immune function.

Asthma in inner city children: recent insights: United States

PURPOSE OF REVIEW

Children living in US inner cities experience disparate burdens of asthma, especially in severity, impairment, exacerbations, and morbidity. Investigations seeking to better understand the factors and mechanisms underlying asthma prevalence, severity, and exacerbation in children living in these communities can lead to interventions that can narrow asthma disparities and potentially benefit all children with asthma. This update will focus on recent (i.e. late 2016-2017) advances in the understanding of asthma in US inner city children.

RECENT FINDINGS

Studies published in the past year expand understanding of asthma prevalence, severity, exacerbation, and the outcomes of guidelines-based management of these at-risk children, including: asthma phenotypes in US inner city children that are severe and difficult-to-control; key environmental determinants and mechanisms underlying asthma severity and exacerbations (e.g. allergy-mediated exacerbation susceptibility to rhinovirus); the importance of schools as a place for provocative exposures (e.g. mouse allergen, nitrogen dioxide) as well as a place where asthma care and outcomes can be improved; and the development and validation of clinically useful indices for gauging asthma severity and predicting exacerbations.

SUMMARY

These recent studies provide a trove of actionable findings that can improve asthma care and outcomes for these at-risk children.

Sex-specific association between prenatal life stress exposure and infant pro-inflammatory cytokine levels during acute respiratory infection

BACKGROUND

Prenatal life stress exposure is linked to dysregulated immune function and chronic inflammatory disease in offspring, but we know little about its effects on infant immune response during viral infection.

METHOD

To address this issue, we examined associations between prenatal life stress exposure and infant upper-airway inflammatory markers during acute respiratory infection (ARI) using data from a prospective, population-based birth-cohort study (N = 180). Infant inflammation was measured as a continuous latent factor within a structural equation modeling framework using nasal wash concentrations of interleukin-1β, interleukin-6, and tumor necrosis factor-α. We hypothesized that infants exposed to prenatal life stress would have greater levels of nasal inflammation during ARI and increased risk for ARI-related morbidity in early childhood.

RESULTS

Our findings contradicted these hypotheses and provided evidence of sexually dimorphic effects of prenatal stress exposure on infant immune functioning during ARI. Among boys, but not girls, prenatal stress was negatively associated with nasal inflammation and indirectly associated with both lower ARI severity and reduced likelihood of subsequent ARI-related hospitalization in the 2nd and 3rd years of life.

CONCLUSION

These data suggest that prenatal stress exposure may be beneficial for infant boys in the context of respiratory viral infections; however, it will be critical to determine if these benefits are offset by increased risk for chronic inflammatory diseases in later childhood. As the participants in this cohort are being followed longitudinally through age 8, we will be able to evaluate long-term health outcomes in future studies.

Longitudinal depression or anxiety in mothers and offspring asthma: a Swedish population-based study

Background

Previous research has found that maternal stress during pregnancy increases the risk of offspring asthma. However, whether this association is consistent with a causal interpretation has never been tested. The objective is to determine whether there is a critical exposure period for maternal depression or anxiety on offspring asthma or whether cumulative exposure is most important, and to investigate evidence of confounding.

Methods

The study population included all children born in Sweden from July 2006 to December 2009 (n = 360 526). Information about childhood asthma, maternal depression or anxiety (diagnosis or medication) and covariates was obtained from the Swedish national health registers. The associations between exposure periods (pre-conception, pregnancy, postnatal or current) and childhood asthma were estimated using structured life course approach hypothesis testing. Paternal and cousin analyses were used to test for evidence of confounding from shared genes and environment.

Results

For childhood asthma, cumulative exposure best described the effect of exposure to maternal depression or anxiety up to a maximum of any two exposure periods [adjusted odds ratio 1.44, 95% confidence interval (CI) 1.38, 1.52]. The hypotheses of a critical period were not supported. The paternal and cousin analyses indicated minimal influence from familial confounding.

Conclusions

These findings support an association between cumulative exposure to maternal depression or anxiety and asthma development in offspring. This association is unique for maternal depression or anxiety and not due to familial confounding. The clinical implication is that effective psychological management of women with chronic distress may reduce offspring asthma risk.

Longitudinal Phenotypes of Respiratory Health in a High-Risk Urban Birth Cohort

RATIONALE

Characterization of patterns of wheezing and allergic sensitization in early life may allow for identification of specific environmental exposures impacting asthma development.

OBJECTIVES

To define respiratory phenotypes in inner-city children and their associations with early-life environmental exposures.

METHODS

Data were collected prospectively from 442 children in the URECA (Urban Environment and Childhood Asthma) birth cohort through age 7 years, reflecting symptoms (wheezing), aeroallergen sensitization, pulmonary function, and body mass index. Latent class mixed models identified trajectories of wheezing, allergic sensitization, and pulmonary function. Cluster analysis defined nonoverlapping groups (termed phenotypes). Potential associations between phenotypes and early-life environmental exposures were examined.

MEASUREMENTS AND MAIN RESULTS

Five phenotypes were identified and mainly differentiated by patterns of wheezing and allergic sensitization (low wheeze/low atopy; low wheeze/high atopy; transient wheeze/low atopy; high wheeze/low atopy; high wheeze/high atopy). Asthma was most often present in the high-wheeze phenotypes, with greatest respiratory morbidity among children with frequent wheezing and allergic sensitization. These phenotypes differentially related to early-life exposures, including maternal stress and depression, antenatal environmental tobacco smoke, house dust microbiome, and allergen content (all P < 0.05). Prenatal smoke exposure, maternal stress, and depression were highest in the high-wheeze/low-atopy phenotype. The high-wheeze/high-atopy phenotype was associated with low household microbial richness and diversity. Early-life aeroallergen exposure was low in high-wheeze phenotypes.

CONCLUSIONS

Patterns of wheezing, allergic sensitization, and lung function identified five respiratory phenotypes among inner-city children. Early-life environmental exposure to stress, depression, tobacco smoke, and indoor allergens and microbes differentially associate with specific phenotypes.

Maternal psychological distress during pregnancy and childhood health outcomes: a narrative review

Maternal psychological distress is common in pregnancy and may influence the risk of adverse outcomes in children. Psychological distress may cause a suboptimal intrauterine environment leading to growth and developmental adaptations of the fetus and child. In this narrative review, we examined the influence of maternal psychological distress during pregnancy on fetal outcomes and child cardiometabolic, respiratory, atopic and neurodevelopment-related health outcomes. We discussed these findings from an epidemiological and life course perspective and provided recommendations for future studies. The literature in the field of maternal psychological distress and child health outcomes is extensive and shows that exposure to stress during pregnancy is associated with multiple adverse child health outcomes. Because maternal psychological distress is an important and potential modifiable factor during pregnancy, it should be a target for prevention strategies in order to optimize fetal and child health. Future studies should use innovative designs and strategies in order to address the issue of causality.

The effects of caregiver depression on childhood asthma: Pathways and mechanisms

OBJECTIVE

To review the literature regarding the effects of caregiver depression on childhood asthma and integrate the findings into a multilevel model of pathways by which these effects occur to further the understanding of the complex biopsychosocial nature of childhood asthma and the key role that is played by caregiver depression.

DATA SOURCES

PubMed was searched for articles published from 2007 to the present (10-year search), and Google Scholar was searched for articles published in 2017 and 2018 to identify the most recent publications.

STUDY SELECTIONS

Studies selected were recent, empirical, or meta-analytic, conducted in humans, and had specific relevance to one or more of the identified pathways. Articles published before 2007 were included if deemed essential because they addressed key pathways, for which there were no more recent articles.

RESULTS

Review of the literature substantiates that caregiver depression plays a key role in the socioeconomic, familial, psychological, and biological cascade of effects on childhood asthma. Childhood asthma outcomes are affected indirectly by socioeconomic status and family stress mediated by caregiver depression, which affects disease management, and/or stress and depression in the child, which, in turn, affect asthma through alterations in immune modulation and autonomic regulation.

CONCLUSION

Findings indicate that future research should concentrate on mediators and moderators to further clarify the complex interplay of these factors that affect childhood asthma. The findings also have substantial translational implications. Given that child stress and depression contribute to asthma disease activity and that treating caregiver depression improves child stress and depression, there is strong rationale for treating depressed caregivers of children with asthma as a component means of improving childhood asthma control.

Association of Maternal Psychosocial Stress With Increased Risk of Asthma Development in Offspring

Prenatal maternal psychosocial stress might influence the development of childhood asthma. Evaluating paternal psychosocial stress and conducting a sibling comparison could provide further insight into the role of unmeasured confounding. We examined the associations of parental psychosocial stress during and after pregnancy with asthma at age 7 years in the Norwegian Mother and Child Cohort Study (n = 63,626; children born in 2000-2007). Measures of psychosocial stress included lifetime major depressive symptoms, current anxiety/depression symptoms, use of antidepressants, anxiolytics, and/or hypnotics, life satisfaction, relationship satisfaction, work stress, and social support. Childhood asthma was associated with maternal lifetime major depressive symptoms (adjusted relative risk (aRR) = 1.19, 95% confidence interval (CI): 1.09, 1.30), in addition to symptoms of anxiety/depression during pregnancy (aRR = 1.17, 95% CI: 1.06, 1.29) and 6 months after delivery (aRR = 1.17, 95% CI: 1.07, 1.28). Maternal negative life events during pregnancy (aRR = 1.10, 95% CI: 1.06, 1.13) and 6 months after delivery (aRR = 1.14, 95% CI: 1.11, 1.18) were also associated with asthma. These associations were not replicated when evaluated within sibling groups. There were no associations with paternal psychosocial stress. In conclusion, maternal anxiety/depression and negative life events were associated with offspring asthma, but this might be explained by unmeasured maternal background characteristics that remain stable across deliveries.

Associations between maternal mental health and early child wheezing in a South African birth cohort

BACKGROUND

Wheezing in early childhood is common and has been identified in high-income countries (HIC) as associated with maternal antenatal or postnatal psychosocial risk factors. However, the association between maternal mental health and childhood wheezing has not been well studied in low and middle-income countries (LMIC), such as South Africa.

METHODS

A total of 1137 pregnant women over 18 year old, between 20 and 28 weeks' gestation, and attending either of two catchment area clinics were enrolled in a South African parent study, the Drakenstein Child Health Study (DCHS). Psychosocial risk factors including maternal depression, psychological distress, early adversity, and intimate partner violence (IPV), were measured antenatally and postnatally by validated questionnaires. Two outcomes were evaluated: Presence of wheeze (at least one episode of child wheeze during the first 2 years of life); and recurrent wheeze (two or more episodes of wheezing in a 12-month period). Logistic regression was used to investigate the association between antenatal or postnatal psychosocial risk factors and child wheeze, adjusting for clinical and socio-demographic covariates.

RESULTS

Postnatal psychological distress and IPV were associated with both presence of wheeze (adjusted OR = 2.09, 95%CI: 1.16-3.77 and 1.63, 95%CI: 1.13-2.34, respectively), and recurrent child wheeze (adjusted OR = 2.26, 95%CI: 1.06-4.81 and 2.20, 95%CI: 1.35-3.61, respectively).

CONCLUSION

Maternal postnatal psychological distress and IPV were associated with wheezing in early childhood. Thus, screening and treatment programs to address maternal psychosocial risk factors may be potential strategies to reduce the burden of childhood wheeze in LMICs.

Evidence establishing a link between prenatal and early-life stress and asthma development

PURPOSE OF REVIEW

The objective of this review is to provide an update on our evolving understanding of the effects of stress in pregnancy and during early development on the onset of asthma-related phenotypes across childhood, adolescence, and into early adulthood.

RECENT FINDINGS

Accumulating evidence over the past 2 decades has established that prenatal and early-life psychological stress and stress correlates (e.g., maternal anxiety or depression) increase the risk for childhood respiratory disorders. Recent systematic reviews and meta-analyses including numerous prospective epidemiological and case-control studies substantiate a significant effect of prenatal stress and stress in early childhood on the development of wheeze, asthma, and other atopic-related disorders (eczema and allergic rhinitis), with many studies showing an exposure-response relationship. Offspring of both sexes are susceptible to perinatal stress, but effects differ. The impact of stress on child wheeze/asthma can also be modified by exposure timing. Moreover, coexposure to prenatal stress can enhance the effect of chemical stressors, such as prenatal traffic-related air pollution, on childhood respiratory disease risk. Understanding complex interactions among exposure dose, timing, child sex, and concurrent environmental exposures promises to more fully characterize stress effects and identify susceptible subgroups. Although the link between perinatal stress and childhood asthma-related phenotypes is now well established, pathways by which stress predisposes children to chronic respiratory disorders are not as well delineated. Mechanisms central to the pathophysiology of wheeze/asthma and lung growth and development overlap and involve a cascade of events that include disrupted immune, neuroendocrine, and autonomic function as well as oxidative stress. Altered homeostatic functioning of these integrated systems during development can enhance vulnerability to asthma and altered lung development.

SUMMARY

Mechanistic studies that more comprehensively assess biomarkers reflecting alterations across interrelated stress response systems and associated regulatory processes, in both pregnant women and young children, could be highly informative. Leveraging high-throughput systems-wide technologies to include epigenomics (e.g., DNA methylation, microRNAs), transcriptomics, and microbiomics as well as integrated multiomics are needed to advance this field of science. Understanding stress-induced physiological changes occurring during vulnerable life periods that contribute to chronic respiratory disease risk could lead to the development of preventive strategies and novel therapeutic interventions.

Development of allergic immunity in early life

The growth and maturity of the peripheral immune system and subsequent development of pulmonary immunity in early life is dictated by host, environmental and microbial factors. Dysregulation during the critical window of immune development in the postnatal years results in disease which impacts on lifelong lung health. Asthma is a common disease in childhood and is often preceded by wheezing illnesses during the preschool years. However, the mechanisms underlying development of wheeze and how and why only some children progress to asthma is unknown. Human studies to date have generally focused on peripheral immune development, with little assessment of local tissue pathology in young children. Moreover, mechanisms underlying the interactions between inflammation and tissue repair at mucosal surfaces in early life remain unknown. Disappointingly, mechanistic studies in mice have predominantly used adult models. This review will consider the aspects of the neonatal immune system which might contribute to the development of early life wheezing disorders and asthma, and discuss the external environmental factors which may influence this process.

Better understanding of childhood asthma, towards primary prevention - are we there yet? Consideration of pertinent literature

Asthma is a chronic disease, characterized by reversible airway obstruction, airway inflammation and hyper-reactivity. The prevalence of asthma has risen dramatically over the past decade, affecting around 300,000,000 people. The etiology is multifactorial, with genetic, epigenetic, developmental and environmental factors playing a role. A complex interaction between the intrauterine environment, the developing immune system, the infant's microbiome and infectious organisms may lead to the development of allergic sensitization and asthma. Thus, a large number of studies have investigated the risk factors for childhood asthma, with a meticulous search of modifiable factors that could aid in primary prevention.

We present a current literature review from 2014-2017, as well as older classic publications, on the pathogenesis and the potential modifiable factors for primary prevention of asthma. No ideal preventive measure has yet been found. Rather, creating favorable prenatal and postnatal environments, minimal exposure to hostile environmental factors, prevention of infections in early life, allergic desensitization and nutritional modifications could possibly reduce asthma inception. In the era of personalized medicine, identifying individual risk factors and tailoring specific preventive measures is warranted.

Role of viral infections in the development and exacerbation of asthma in children

Viral infections are closely linked to wheezing illnesses in children of all ages. Respiratory syncytial virus (RSV) is the main causative agent of bronchiolitis, whereas rhinovirus (RV) is most commonly detected in wheezing children thereafter. Severe respiratory illness induced by either of these viruses is associated with subsequent development of asthma, and the risk is greatest for young children who wheeze with RV infections. Whether viral illnesses actually cause asthma is the subject of intense debate. RSV-induced wheezing illnesses during infancy influence respiratory health for years. There is definitive evidence that RSV-induced bronchiolitis can damage the airways to promote airway obstruction and recurrent wheezing. RV likely causes less structural damage and yet is a significant contributor to wheezing illnesses in young children and in the context of asthma. For both viruses, interactions between viral virulence factors, personal risk factors (eg, genetics), and environmental exposures (eg, airway microbiome) promote more severe wheezing illnesses and the risk for progression to asthma. In addition, allergy and asthma are major risk factors for more frequent and severe RV-related illnesses. Treatments that inhibit inflammation have efficacy for RV-induced wheezing, whereas the anti-RSV mAb palivizumab decreases the risk of severe RSV-induced illness and subsequent recurrent wheeze. Developing a greater understanding of personal and environmental factors that promote more severe viral illnesses might lead to new strategies for the prevention of viral wheezing illnesses and perhaps reduce the subsequent risk for asthma.

Lessons learned from birth cohort studies conducted in diverse environments

Childhood asthma develops from a complex interaction among host and environmental factors in early life. Birth cohort studies have provided valuable insight into asthma risk factors and the natural history of wheezing and asthma through childhood and beyond. Early life aeroallergen sensitization and wheezing illnesses associated with virus and bacterial infections have been identified as pivotal risk factors for asthma inception. Recently, focus has turned toward protective factors that promote lung health in children. Studies in a variety of environments, including farms and urban communities, suggest that diverse exposures to microbes in early life lead to a lower risk of allergy and asthma in childhood. The mechanisms underlying how these exposures and the gut and airway microbiomes alter the host response to allergens and viruses are of interest and an area of ongoing study. Longitudinal follow up of birth cohorts in diverse environments worldwide will continue to provide critical knowledge about the factors that impact the natural history of asthma.