Sex and gender differences in lung development and their clinical significance

Sex and gender differences during the lung lifespan: unveiling a pivotal impact

Sex and gender differences significantly influence lung parenchyma development, beginning as early as the embryonic stages of human life. Although this association is well known in the clinical manifestations of some relevant pulmonary diseases, there is less data available regarding their effects on cell biological programmes across different stages of body development. A deep understanding of these mechanisms could help in defining preventive strategies tailored to a fully personalised approach to respiratory medicine. From this perspective, this review aims to analyse the influence of sex and gender on bronchoalveolar and vascular compartments from embryonic and neonatal stages through to adolescence, adulthood and elder age.

Association between serum albumin and pulmonary function in adolescents: analyses of NHANES 2007-2012

BACKGROUND

Pulmonary function tests (PFTs) are an important tool for assessing pulmonary diseases, although clinicians often find it challenging to accurately evaluate the pulmonary function of children.

METHODS

We intend to investigate the association between serum albumin (SA) and lung function among U.S. adolescents. This cross-sectional study included 3,072 adolescents (aged 12 to 19) from 2007 to 2012National Health and Nutrition Examination Survey (NHANES). PFTs, including forced vital capacity (FVC)%predicted, forced expiratory volume in 1 s (FEV1)%predicted, FEV1/FVC%predicted, and maximum mid-expiratory flow (FEF25-75) % predicted, were utilized to assess the association between serum albumin levels and lung function. To explore the potential associations between SA and pulmonary function, we employed multivariate linear regression, subgroup analysis, smoothing curve fitting and threshold effect.

RESULTS

A positive correlation was observed between serum albumin levels and pulmonary function. In the model with a fully adjusted, each 1 g/dL serum albumin increase in SA corresponded to an increase of 2.69% in FVC%pred, 5.8% in FEV1%pred, 10.99% in FEF25-75%pred and 2.98% in FEV1/FVC%pred. This association between SA and FEV1%pred differed across gender subgroups. A non-linear relationship was observed between SA and FEV1/FVC%pred.

CONCLUSION

Our results demonstrated a positive correlation between SA and lung function, suggesting a novel modality for evaluating pulmonary function, specifically in children.

CLINICAL TRIAL NUMBER

Not applicable.

Dysregulation of CITED2 in abnormal lung development in the nitrofen rat model

PURPOSE

CITED2 both modulates lung, heart and diaphragm development. The role of CITED2 in the pathogenesis of congenital diaphragmatic hernia (CDH) is unknown. We aimed to study CITED2 during abnormal lung development in the nitrofen model.

METHODS

Timed-pregnant rats were given nitrofen on embryonic day (E) 9 to induce CDH. Fetal lungs were harvested on E15, 18 and 21. We performed RT-qPCR, RNAscope™ in situ hybridization and immunofluorescence staining for CITED2.

RESULTS

We observed no difference in RT-qPCR (control: 1.09 ± 0.22 and nitrofen: 0.95 ± 0.18, p = 0.64) and in situ hybridization (1.03 ± 0.03; 1.04 ± 0.03, p = 0.97) for CITED2 expression in E15 nitrofen and control pups. At E18, CITED2 expression was reduced in in situ hybridization of nitrofen lungs (1.47 ± 0.05; 1.14 ± 0.07, p = 0.0006), but not altered in RT-qPCR (1.04 ± 0.16; 0.81 ± 0.13, p = 0.33). In E21 nitrofen lungs, CITED2 RNA expression was increased in RT-qPCR (1.04 ± 0.11; 1.52 ± 0.17, p = 0.03) and in situ hybridization (1.08 ± 0.07, 1.29 ± 0.04, p = 0.02). CITED2 protein abundance was higher in immunofluorescence staining of E21 nitrofen lungs (2.96 × 109 ± 0.13 × 109; 4.82 × 109 ± 0.25 × 109, p < 0.0001).

CONCLUSION

Our data suggest that dysregulation of CITED2 contributes to abnormal lung development of CDH, as demonstrated by the distinct spatial-temporal distribution in nitrofen-induced lungs.

Fetal thoracic circumference in mid-pregnancy and infant lung function

BACKGROUND AND AIM

Impaired lung function in early infancy is associated with later wheeze and asthma, while fetal thoracic circumference (TC) predicts severity of neonatal lung hypoplasia. Exploring fetal origins of lung function in infancy, we aimed to determine if fetal TC in mid-pregnancy was associated with infant lung function.

METHODS

From the prospective Scandinavian general population-based PreventADALL mother-child birth cohort, all 851 3-month-old infants with tidal flow-volume measurements in the awake state and ultrasound fetal size measures at 18 (min-max 16-22) weeks gestational age were included. Associations between fetal TC and time to peak tidal expiratory flow to expiratory time (t_PTEF /t_E ) were analyzed in linear regression models. To account for gestational age variation, we adjusted TC for simultaneously measured general fetal size, by head circumference (TC/HC), abdominal circumference (TC/AC), and femur length (TC/FL). Multivariable models were adjusted for maternal age, maternal asthma, pre-pregnancy body mass index, parity, nicotine exposure in utero, and infant sex.

RESULTS

The infants (47.8% girls) were born at mean (SD) gestational age of 40.2 (1.30) weeks. The mean (SD) t_PTEF /t_E  was 0.39 (0.08). The mean (SD) TC/HC was 0.75 (0.04), TC/AC 0.87 (0.04), and TC/FL 4.17 (0.26), respectively. Neither TC/HC nor TC/AC were associated with infant t_PTEF /t_E while a week inverse association was observed between TC/FL and t_PTEF /t_E  ( β ^ $\hat{\beta }$  = -0.03, 95% confidence interval [-0.05, -0.007], p = 0.01).

CONCLUSION

Mid-pregnancy fetal TC adjusted for fetal head or abdominal size was not associated with t_PTEF /t_E in healthy, awake 3-month-old infants, while a weak association was observed adjusting for fetal femur length.

Infant lung function and maternal physical activity in the first half of pregnancy

Background and aim

Physical activity (PA) in pregnancy is important for maternal and possibly offspring health. To study the early origins of lung function we aimed to determine whether PA in the first half of pregnancy is associated with lung function in healthy 3-month-old infants.

Methods

From the general population-based Preventing Atopic Dermatitis and Allergies in Children birth cohort recruiting infants antenatally in Norway and Sweden, all 812 infants (48.8% girls) with available tidal flow-volume measures in the awake state at 3 months of age and mid-pregnancy data on PA were included. PA was self-reported by the mothers and, based on intensity, we categorised them as active or inactive during pregnancy. Furthermore, we defined active mothers as fairly or highly active. The main outcome was a ratio of time to peak tidal expiratory flow to expiratory time (t PTEF/t E) <0.25. Associations were analysed by logistic regression, adjusting for maternal age, education, parity, pre-pregnancy body mass index, in utero nicotine exposure and parental atopy.

Results

The mean±sd t PTEF/t E was 0.391±0.08 and did not differ significantly according to maternal PA level in pregnancy. The 290 infants of inactive mothers had higher odds of having t PTEF/t E <0.25 compared to infants of all active mothers (OR 2.07, 95% CI 1.13-3.82; p=0.019) and compared to infants (n=224) of fairly active (OR 2.83, 95% CI 1.26-7.24; p=0.018) but not highly active mothers (n=298).

Conclusion

Based on self-reported maternal PA in the first half of pregnancy, 3-month-old infants of inactive compared to active mothers had higher odds of a low t PTEF/t E.

Nebulized Magnesium Sulphate in Bronchiolitis: A Randomized Controlled Trial

OBJECTIVE

To evaluate the efficacy and safety of nebulized magnesium sulphate as a bronchodilator in young children aged 1-24 mo with moderate to severe bronchiolitis in comparison to standard therapy.

METHODS

This was an open labeled randomized controlled trial comprising 60 children with moderate to severe bronchiolitis which was randomly assigned to 2 groups. Intervention group received nebulization with 3 mL of 3.2% magnesium sulphate (MgSO₄) (iso-osmolar) every 4 hourly for 24 h in addition to standard care and the control group received standard care alone. The primary outcome measure was to compare the improvement of bronchiolitis severity score (BSS) and length of hospitalization. The secondary outcome was to measure the need for noninvasive ventilation, need for admission to intensive care unit (ICU) in the initial visit, to evaluate the safety of magnesium sulphate and need for clinic revisit, hospital readmission and ICU readmission within 2 wk after discharge in both the groups.

RESULTS

The mean age of children allocated in the control group was 7.4 ± 5.1 mo and 7.7 ± 4.5 mo in the intervention group. There was no significant difference with respect to improvement of BSS or reduced length of hospitalization in both the groups (p > 0.05). BSS monitored sequentially after enrollment at 1, 2, 4, 8, 12, 16, and 24 h did not show statistically significant differences between the groups. Mean length of hospital stay was 2.89 ± 2.25 d in treatment group and 2.96 ± 1.86 d in control group (p = 0.902). No adverse events were observed in both the groups.

CONCLUSION

Nebulized magnesium sulphate is not superior to standard therapy in children with moderate to severe bronchiolitis.

CLINICAL TRIAL REGISTRATION NUMBER

CTRI/2018/06/014400.

Sex and Gender Differences in Lung Disease

Sex differences in the anatomy and physiology of the respiratory system have been widely reported. These intrinsic sex differences have also been shown to modulate the pathophysiology, incidence, morbidity, and mortality of several lung diseases across the life span. In this chapter, we describe the epidemiology of sex differences in respiratory diseases including neonatal lung disease (respiratory distress syndrome, bronchopulmonary dysplasia) and pediatric and adult disease (including asthma, cystic fibrosis, idiopathic pulmonary fibrosis, chronic obstructive pulmonary disease, lung cancer, lymphangioleiomyomatosis, obstructive sleep apnea, pulmonary arterial hypertension, and respiratory viral infections such as respiratory syncytial virus, influenza, and SARS-CoV-2). We also discuss the current state of research on the mechanisms underlying the observed sex differences in lung disease susceptibility and severity and the importance of considering both sex and gender variables in research studies' design and analysis.

DNA methylation at birth is associated with lung function development until age 26 years

Little is known about whether DNA methylation (DNAm) of cytosine-phosphate-guanine (CpG) sites at birth predicts patterns of lung function development. We used heel prick DNAm from the F1-generation of Isle of Wight birth cohort (IOWBC-F1) for discovery of CpGs associated with lung function trajectories (forced expiratory volume in 1 s, forced vital capacity, their ratio, and forced expiratory flow at 25-75% of forced vital capacity) over the first 26 years, stratified by sex. We replicated the findings in the Avon Longitudinal Study of Parents and Children (ALSPAC) using cord blood DNAm.Epigenome-wide screening was applied to identify CpGs associated with lung function trajectories in 396 boys and 390 girls of IOWBC-F1. Replication in ALSPAC focussed on lung function at ages 8, 15 and 24 years. Statistically significantly replicated CpGs were investigated for consistency in direction of association between cohorts, stability of DNAm over time in IOWBC-F1, relevant biological processes and for association with gene expression (n=161) in IOWBC F2-generation (IOWBC-F2).Differential DNAm of eight CpGs on genes GLUL, MYCN, HLX, LHX1, COBL, COL18A1, STRA6, and WNT11 involved in developmental processes, were significantly associated with lung function in the same direction in IOWBC-F1 and ALSPAC, and showed stable patterns at birth, aged 10 and 18 years between high and low lung function trajectories in IOWBC-F1. CpGs on LHX1 and COL18A1 were linked to gene expression in IOWBC-F2.In two large cohorts, novel DNAm at birth were associated with patterns of lung function in adolescence and early adulthood providing possible targets for preventative interventions against adverse pulmonary function development.

Early prediction of moderate to severe bronchopulmonary dysplasia in extremely premature infants

BACKGROUND

Bronchopulmonary Dysplasia (BPD) is the commonest morbidity in extremely preterm infants (PTIs). Risk factors for BPD have been described in the era before the widespread availability of non-invasive ventilation (NIV) in the delivery room (DR). The objective of this study is to identify risk factors for Moderate/Severe BPD in an era of widespread availability of NIV in the DR.

METHODS

Detailed antenatal and postnatal data were abstracted for PTIs, 23^0/7-27^6/7 weeks GA. Multivariate logistic regression and classification and regression tree analyses (CART) identified predictors for the primary outcome of Moderate/Severe BPD.

RESULTS

Of 263 eligible infants, 59% had Moderate/Severe BPD. Moderate/Severe BPD was significantly associated with birthweight, gender, DR intubation and surfactant compared to No/Mild BPD. Of infants not intubated in the DR, 40% with No/Mild BPD and 80% with Moderate/Severe BPD received intubation by 48 hours (p < 0.05). Infants with Moderate/Severe BPD received longer duration of oxygen and mechanical (MV). On logistic regression, birthweight, gender, oxygen concentration, cumulative duration of oxygen and MV, surfactant, and blood transfusions predicted Moderate/Severe BPD. Both CART analysis and logistic regression showed duration of oxygen and MV to be the most important predictors for Moderate/Severe BPD.

CONCLUSIONS

In an era of increasing availability of NIV in the DR, lower birthweight, male gender, surfactant treatment, blood transfusions and respiratory support in the first 2-3 weeks after birth predict Moderate/Severe BPD with high sensitivity and specificity. The majority of these infants received intubation within 48 hours of birth (97%). These data suggest that early failures of NIV represent opportunities for improvement of NIV techniques and of non-invasive surfactant to avoid intubation in the first 48 hours. Furthermore, these risk factors may allow earlier identification of infants most likely to benefit from interventions to prevent or decrease severity of BPD.

Respiratory syncytial virus infection: why does disease severity vary among individuals?

Introduction: Respiratory syncytial virus (RSV) is the most common cause of acute lower respiratory tract infections in infancy. While many infants are infected with RSV, the nature and severity of the disease vary among individuals. RSV causes bronchiolitis, pneumonia, and asthma exacerbation. However, most children infected with RSV have only mild upper airways disease and may be asymptomatic.Areas covered: Despite efforts to elucidate mechanisms for the various clinical responses to RSV infection, they remain largely unknown, suggesting that susceptibility and disease are influenced by multiple intrinsic and extrinsic factors. This article reviews the available literature on the field of RSV disease severity and discusses important factors associated to susceptibility and different disease outcome.Expert opinion: The severity of RSV-induced illness is a phenomenon that depends on a variety of graded mechanisms of interaction between the host, virus, and environment. This may lead to differences in the intensity of immune response in the lung and different courses of the disease. By characterizing, classifying, and grading the affecting factors in high-risk patients versus those who do not fall ill by RSV, we may find therapies or point to disease-limiting medications.

The association between gender and pediatric respiratory morbidity

OBJECTIVE

To evaluate the association between newborn gender and the risk for later pediatric respiratory morbidity.

STUDY DESIGN

A population based cohort analysis was performed by comparing the risk of long-term respiratory morbidity (until 18 years of age) according to gender. Respiratory morbidity included hospitalizations involving pneumonia, asthma, bronchitis, bronchiolitis, upper respiratory tract infection (URTI), influenza, and bronchiectasis. Deliveries occurred between the years 1991 and 2014 in a tertiary medical center. Kaplan-Meier survival curves were constructed to compare cumulative respiratory morbidity. A Cox proportional hazards model controlled for confounders.

RESULTS

During the study period 240 953 newborns met the inclusion criteria. Among them, 118 113 were females (49.0%) and 122 840 were males (51.0%). During the 18 years of follow-up, 13 719 (5.7%) different newborns were hospitalized with respiratory related morbidity. Males had significantly higher rates of respiratory morbidity as compared with females (6.4% vs 4.9% respectively, P < 0.001, OR 1.32, 95% CI 1.28-1.37). Specifically, pneumonia, bronchitis, asthma, bronchiolitis, and URTI were significantly more common in males. Males exhibited higher total cumulative respiratory morbidity (log rank P < 0.001), as well as higher cumulative morbidity in several sub-categories. These sub-categories included pneumonia, bronchitis, asthma, bronchiolitis, and URTI (P < 0.05 in all). The Cox regression model demonstrated male gender to be an independent risk factor for pediatric respiratory morbidity while adjusting for gestational age, birthweight, and other confounders (HR 1.29, 95% CI 1.25-1.34, P < 0.001).

CONCLUSIONS

Males are at an increased risk for pediatric respiratory morbidity, independent of obstetrical characteristics such as gestational age and birthweight.

Severe bronchopulmonary dysplasia - incidence and predictive factors in a prospective, multicenter study in very preterm infants with respiratory distress syndrome

BACKGROUND

Severe bronchopulmonary dysplasia (BPD) remains a major complication of prematurity and can have significant impact on long-term pulmonary sequelae and adverse neurodevelopmental outcomes.

OBJECTIVE

To assess the incidence and evaluate the predictive factors for severe BPD in very preterm infants with respiratory distress syndrome.

METHODS

Of the 846 premature infants born at ≤32-week gestation who developed respiratory distress syndrome (RDS), 707 infants with known oxygen dependency at 36 weeks gestational age were included in the analysis of BPD incidence. With univariate and multiple logistic regression models we evaluated the risk factors for the development of severe BPD and calculated odds ratios (ORs).

RESULTS

The overall incidence of BPD was 45.2%. Severe BPD accounted for 6%, with morbidity pertaining mainly to infants <29-week gestation (incidence 10%). The risk factors for severe BPD included male gender (OR 3.02 95%CI 1.30-7.46), intubation in the delivery room (OR 2.57, 95%CI 1.00-7.18), and invasive ventilation >7 days (OR 7.05, 95%CI 2.63-22.4). The protective factors were early continuous positive airway pressure (CPAP) in the univariate analysis and receiving surfactant <15 min after birth in the multivariate model.

CONCLUSIONS

Mechanical ventilation >7 days is the most prevalent risk factor for severe BPD. CPAP initiated in the delivery room and early surfactant are key preventive measures.

Sexual dimorphism of the pulmonary transcriptome in neonatal hyperoxic lung injury: identification of angiogenesis as a key pathway

Bronchopulmonary dysplasia (BPD) is characterized by impaired alveolar secondary septation and vascular growth. Exposure to high concentrations of oxygen (hyperoxia) contributes to the development of BPD. The male sex is considered an independent risk factor for the development of BPD. The reasons underlying sexually dimorphic outcomes in premature neonates are not known. We hypothesized that sex-specific modulation of biological processes in the lung under hyperoxic conditions contributes to sex-based differences. Neonatal male and female mice (C57BL/6) were exposed to hyperoxia [95% [Formula: see text], postnatal day (PND) 1-5: saccular stage of lung development] and euthanized on PND 7 or 21. Pulmonary gene expression was studied using RNA-Seq on the Illumina HiSeq 2500 platform. Analysis of the pulmonary transcriptome revealed differential sex-specific modulation of crucial pathways such as angiogenesis, response to hypoxia, inflammatory response, and p53 pathway. Candidate genes from these pathways were validated at the mRNA level by qPCR. Analysis also revealed sex-specific differences in the modulation of crucial transcription factors. Focusing on the differential modulation of the angiogenesis pathway, we also showed sex-specific differential activation of Hif-1α-regulated genes using ChIP-qPCR and differences in expression of crucial genes (Vegf, VegfR2, and Phd2) modulating angiogenesis. We demonstrate the translational relevance of our findings by showing that our murine sex-specific differences in gene expression correlate with those from a preexisting human BPD data set. In conclusion, we provide novel molecular insights into differential sex-specific modulation of the pulmonary transcriptome in neonatal hyperoxic lung injury and highlight angiogenesis as one of the crucial differentially modulated pathways.

Early smoke exposure is associated with asthma and lung function deficits in adolescents

OBJECTIVE

Early life tobacco smoke exposure may influence asthma, lung function and lung function growth into adolescence. We aimed to determine the associations between perinatal smoke exposure and asthma and lung function up to 18 years of age.

METHODS

We prospectively recorded perinatal parental smoking and measured respiratory outcomes at 12 and 18 years in the Melbourne Atopy Cohort Study (MACS), a longitudinal birth cohort. Multiple logistic regression was used to analyse the associations between perinatal smoke exposure and asthma at 12 (n = 370) and 18 years (n = 411). Multiple linear regression was used to investigate the relationship between perinatal smoking and: lung function (12 and 18 years) and lung function growth (between 12 and 18 years).

RESULTS

At 18 years, girls exposed to parental smoking during the perinatal period had increased odds of asthma (OR: 3.45, 95%CI: 1.36, 8.77), reduced pre-bronchodilator Forced expiratory volume in one-second (FEV₁) (-272 ml/s; -438, -107); FEV₁/ forced vital capacity (FVC) (-0.038; -0.065, -0.010); mid expiratory flow (MEF_25-75) (-430 ml/s; -798, -61), and reduced post-bronchodilator FEV₁/FVC (-0.028, -0.053, -0.004). No associations were found for boys (pre-bronchodilator FEV₁ 26ml/s; -202, 255; FEV₁/FVC 0.018; -0.013, 0.049).

CONCLUSIONS

Perinatal smoke may affect risk of asthma, reduce lung function and lung function growth in adolescence. Girls appear to be more susceptible than boys.

Increasing awareness of sex differences in airway diseases

There is growing epidemiologic data demonstrating sex differences with respect to prevalence and progression of airway diseases, including asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF) and non-CF-related bronchiectasis. In asthma, for example, young boys have increased exacerbations and higher morbidity than girls which distinctly reverses after adolescence and into adulthood. In COPD, a disease that was historically considered an illness of men, the number of women dying per year is now greater than in men. Finally, women with CF-related bronchiectasis have a decreased median life expectancy relative to men and a higher risk of respiratory infections despite equal prevalence of the disease. A number of studies now exist demonstrating mechanisms behind these sex differences, including influences of genetic predisposition, sex hormones and comorbidities. The notable sex disparity has potential diagnostic, therapeutic and prognostic implications and for the practicing respiratory or general physician, a familiarity with these distinctions may augment effective management of patients with airway diseases. This review seeks to concisely summarize the data regarding gender-based differences in airway diseases, outline the current understanding of contributing factors and discuss therapeutic implications for clinicians.

Sex and the lung: Observations, hypotheses, and future directions

Sex-related differences in a variety of lung diseases in infants and young children are reviewed, including respiratory distress syndrome, and chronic lung disease of prematurity, lower respiratory tract illnesses and wheezing, asthma, diffuse, and interstitial lung diseases, and cystic fibrosis. Differences in anatomy and physiology, such as airway size, airway muscle bulk, airway reactivity, airway tone, and cough reflexes may explain much of these sex differences. Better understanding of sex-related lung differences could help personalize respiratory treatment.

Childhood Asthma Management and Environmental Triggers

Asthma is the most common chronic disease among children. It cannot be prevented but can be controlled. Industrialized countries experience high lifetime asthma prevalence that has increased over recent decades. Asthma has a complex interplay of genetic and environmental triggers. Studies have revealed complex interactions of lung structure and function genes with environmental exposures such as environmental tobacco smoke and vitamin D. Home environmental strategies can reduce asthma morbidity in children but should be tailored to specific allergens. Coupled with education and severity-specific asthma therapy, tailored interventions may be the most effective strategy to manage childhood asthma.

BMI, waist circumference at 8 and 12 years of age and FVC and FEV1 at 12 years of age; the PIAMA birth cohort study

BACKGROUND

In adults, overweight is associated with reduced lung function, in children evidence on this association is conflicting. We examined the association of body mass index (BMI) and waist circumference (WC) at age 12, and of persistently (at ages 8 and 12 years) high BMI and large WC, with forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) at age 12.

METHODS

Height, weight, WC and FVC and FEV1 were measured during a medical examination in 1288 12-year-olds participating in the PIAMA birth cohort study. 1090 children also had BMI and WC measured at age 8. The associations between BMI and WC and FVC, FEV1, and FEV1/FVC ratio were studied using local and linear regression analyses, separately for girls and boys. The regression models were adjusted for age, height, and pubertal development and maternal educational level.

RESULTS

High BMI and large WC (sd-score >90th percentile) were associated with higher FVC; in girls these associations were statistically significant (4.6% (95% CI: 1.5, 7.9) and 3.6% (95% CI: 0.6, 6.8) respectively in adjusted models). Similar associations were observed for persistently high BMI or large WC: girls with a high BMI or large WC at both 8 and 12 years had statistically significantly higher FVC at age 12 years (BMI: 4.9% (95% CI 0.9, 9.1), WC: 5.0% (95% CI 0.7, 9.6)) than girls with normal BMI or WC at both ages. No statistically significant associations were observed between (persistently) high BMI or large WC and FEV1. The FEV1/FVC ratio was statistically significantly lower in children with a high BMI or large WC than in children with a normal BMI or WC. Girls and boys with a persistently high BMI or large WC status had statistically significantly lower FEV1/FVC ratios.

CONCLUSION

At 12 years of age, a persistently high BMI or large WC is not yet associated with lower FVC and FEV1, suggesting that this association, that is commonly observed in adults, develops at a later age.

Sex steroid signaling: implications for lung diseases

There is increasing recognition that sex hormones (estrogen, progesterone, and testosterone) have biological and pathophysiological actions in peripheral, non-reproductive organs, including the lung. Clinically, sex differences in the incidence, morbidity and mortality of lung diseases such as asthma, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis, lung cancer and pulmonary hypertension have been noted, although intrinsic sex differences vs. the roles of sex steroids are still not well-understood. Accordingly, it becomes important to ask the following questions: 1) Which sex steroids are involved? 2) How do they affect different components of the lung under normal circumstances? 3) How does sex steroid signaling change in or contribute to lung disease, and in this regard, are sex steroids detrimental or beneficial? As our understanding of sex steroid signaling in the lung improves, it is important to consider whether such information can be used to develop new therapeutic strategies to target lung diseases, perhaps in both sexes or in a sex-specific manner. In this review, we focus on the basics of sex steroid signaling, and the current state of knowledge regarding how they influence structure and function of specific lung components across the life span and in the context of some important lung diseases. We then summarize the potential for sex steroids as useful biomarkers and therapeutic targets in these lung diseases as a basis for future translational research in the area of gender and individualized medicine.

Factors affecting nasal intermittent positive pressure ventilation failure and impact on bronchopulmonary dysplasia in neonates

BACKGROUND

Nasal intermittent positive pressure ventilation (NIPPV) is becoming more important as a mode of ventilation in premature neonates predisposed to development of bronchopulmonary dysplasia (BPD). To the best of our knowledge, there have been no detailed studies characterizing neonates who fail NIPPV.

OBJECTIVE

To determine the differences between neonates who are successfully extubated to NIPPV and those who require re-intubation from NIPPV, and the impact of timing of NIPPV failure on BPD rates.

STUDY DESIGN

This was a retrospective cohort study in which we included infants with gestational age (GA) ⩽ 28 weeks and birth weight ⩽ 1000 g. χ²-test, analysis of variance and multivariate logistic regression models were used.

RESULTS

Two hundred and forty infants were studied; 180 failed NIPPV and of those, 33 (18%), 39 (22%) and 108 (60%) failed NIPPV within 0 to 6 h, ⩾ 6 to 24 h and ⩾ 24 h, respectively. Female sex and increased weight were protective against NIPPV failure (adjusted odds ratio (95% confidence interval): 0.28 (0.14 to 0.58), 0.04 (0.01 to 0.22)). Increased GA at extubation and female sex were both associated with increased time to failure (P=0.008, <0.001, respectively). Apnea was more likely the cause for failure ⩾ 24 h (P=0.015), whereas increased work of breathing/fraction of inspired oxygen requirements were more significant when NIPPV failure occurred earlier (P=0.001). Neonates who failed NIPPV within 24 h did not have any association with likelihood of developing BPD or severity of BPD, after adjusting for confounding variables.

CONCLUSION

Significant differences in neonatal characteristics may help identify which neonates are more likely to fail NIPPV, and their timing of failure.

Obesity in children with poorly controlled asthma: Sex differences

BACKGROUND

Obesity increases asthma risk, and may alter asthma severity. In adults, sex appears to modify the effect of obesity on asthma. Among children, the effect of sex on the relationship between obesity and asthma severity remains less clear, particularly when considering race.

OBJECTIVE

To determine how obesity affects disease characteristics in a diverse cohort of children with poorly controlled asthma, and if obesity effects are altered by sex.

DESIGN

We analyzed 306 children between 6 and 17 years of age with poorly controlled asthma enrolled in a 6-month trial assessing lansoprazole for asthma control. In this secondary analysis, we determined associations between obesity and symptom severity, spirometry, exacerbation risk, airway biomarkers, bronchial reactivity, and airflow perception. We used both a multivariate linear regression and longitudinal mixed-effect model to determine if obesity interacted with sex to affect asthma severity.

RESULTS

Regardless of sex, BMI >95th percentile did not affect asthma control, exacerbation risk or airway biomarkers. Sex changed the effect of obesity on lung function (sex × obesity FEV1%, interaction P-value < 0.01, sex × obesity FEV1/FVC, interaction P-value = 0.03). Obese males had significantly worse airflow obstruction compared to non-obese males, while in females there was no obesity effect on airflow obstruction. In females, obesity was associated with significantly greater FEV1 and FVC, and a trend toward reduced airway reactivity.

CONCLUSIONS

Obesity did not affect asthma control, airway markers or disease stability; however obesity did affect lung function in a sex-dependent manner. In males, obesity associated with reduced FEV1/FVC, and in females, obesity associated with substantially improved lung function.

Early lung development: lifelong effect on respiratory health and disease

Interest in the contribution of changes in lung development during early life to subsequent respiratory morbidity is increasing. Most evidence of an association between adverse intrauterine factors and structural effects on the developing lung is from animal studies. Such evidence has been augmented by epidemiological studies showing associations between insults to the developing lung during prenatal and early postnatal life and adult respiratory morbidity or reduced lung function, and by physiological studies that have elucidated mechanisms underlying these associations. The true effect of early insults on subsequent respiratory morbidity can be understood only if the many prenatal and postnatal factors that can affect lung development are taken into account. Adverse factors affecting lung development during fetal life and early childhood reduce the attainment of maximum lung function and accelerate lung function decline in adulthood, initiating or worsening morbidity in susceptible individuals. In this Review, we focus on factors that adversely affect lung development in utero and during the first 5 years after birth, thereby predisposing individuals to reduced lung function and increased respiratory morbidity throughout life. We focus particularly on asthma and COPD.

Waist circumference, BMI, and lung function in 8-year-old children: the PIAMA birth cohort study

BACKGROUND

Body mass index (BMI) and waist circumference (WC) may be associated with lung function in children, as observed in adults.

METHODS

Height, weight, waist circumference, and lung function (FVC and FEV1 ) were measured during a medical examination in 1,058 eight-year-old children participating in the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort study.

RESULTS

After adjusting for height, age and other potential confounders large WC or high BMI (>90th percentile) were not associated with forced expiratory volume in 1 sec (FEV1) or forced vital capacity (FVC). In girls only, large WC was, independently of BMI, associated with 3.5% (95% confidence interval (CI): -6.4, -0.6) lower FEV1 /FVC ratio in the model including WC and BMI. Girls with low BMI (<10th percentile) had 4.6% lower FEV1 (95% CI: -8.4, -0.6) and 5.1% lower FVC (95% CI: -8.8, -1.2) than girls with normal BMI. In boys, we did not observe associations between low or high BMI and lung function independent of WC, or between small or large WC and lung function after adjustment for BMI.

CONCLUSION

At 8 years of age, a high BMI or large WC are not yet associated with FEV1 and FVC, indicating that this association may change over the course of life from childhood to adulthood.

Early-onset chronic obstructive pulmonary disease is associated with female sex, maternal factors, and African American race in the COPDGene Study

RATIONALE

The characterization of young adults who develop late-onset diseases may augment the detection of novel genes and promote new pathogenic insights.

METHODS

We analyzed data from 2,500 individuals of African and European ancestry in the COPDGene Study. Subjects with severe, early-onset chronic obstructive pulmonary disease (COPD) (n=70, age < 55 yr, FEV1 < 50% predicted) were compared with older subjects with COPD (n =306, age >64 yr, FEV1 <50% predicted).

MEASUREMENTS AND MAIN RESULTS

Subjects with severe, early-onset COPD were predominantly females (66%), P =0.0004. Proportionally,early-onset COPD was seen in 42% (25 of 59) of African Americans versus 14% (45 of 317) of non-Hispanic whites, P <0.0001. Other risk factors included current smoking (56 vs. 17%, P < 0.0001) and self-report of asthma (39 vs. 25%, P =0.008). Maternal smoking (70 vs. 44%, P=0.0001) and maternal COPD (23 vs.12%, P=0.03) were reported more commonly in subjects with early-onset COPD. Multivariable regression analysis found association with African American race, odds ratio (OR), 7.5 (95% confidence interval [CI], 2.3–24; P ¼=0.0007); maternal COPD, OR, 4.7 (95% CI,1.3–17; P=0.02); female sex, OR, 3.1 (95% CI, 1.1–8.7; P=0.03); and each pack-year of smoking, OR, 0.98 (95% CI, 0.96–1.0; P ¼ 0.03).

CONCLUSIONS

These observations support the hypothesis that severe, early-onset COPD is prevalent in females and is influenced by maternal factors. Future genetic studies should evaluate (1) gene-by-sex interactions to address sex-specific genetic contributions and (2) gene-by-race interactions.

Lower respiratory tract infections and gastrointestinal infections among mature babies in Japan

BACKGROUND

Epidemiologic evidence regarding the background factors of childhood infections in Japan is scarce. The aim of the present study was therefore to investigate the rates and associated factors of hospitalization for lower respiratory tract infections (LRTI) and gastrointestinal infections (GII) among children with birthweight ≥ 2500 g and ≥ 37 weeks of gestational age.

METHOD

The data for the study were collected at 18-month health checkups in one city in Japan. The community database included information on the main outcome (past hospitalization) and 16 host, environmental, and parenting factors. The Kaplan-Meier method and log-rank test were used to determine sex differences in hospital admission for infection, and the Cox regression model to analyze sex-specific factors associated with the hospitalization.

RESULTS

The proportion of children who were admitted to hospital before their 18-month checkup was 7.1% for LRTI and 2.2% for GII. Hospital admission for LRTI among boys was higher than girls. Multivariate analysis indicated the following LRTI-associated factors: child-care attendance (hazard ratio [HR]= 1.97) and three or more adults living together (HR = 2.63) for boys; and child-care attendance (HR = 4.30) and two or more children living together (HR = 4.57) for girls. GII-associated factors were maternal age <25 years (HR = 3.45) for boys, and hand washing by caregivers after lavatory use and diaper changing (HR = 6.93) for girls.

CONCLUSIONS

One out of 11 children was hospitalized because of LRTI or GII during their first 18 months, which was associated with a biologic factor (sex), environmental factors (child-care attendance and family size), and parenting practices (shorter duration of exclusive breast-feeding and caregivers' unfavorable hygiene practices).

Asthma in childhood: a complex, heterogeneous disease

Asthma in childhood is a heterogeneous disease with different phenotypes and variable clinical manifestations, which depend on the age, gender, genetic background, and environmental influences of the patients. Several longitudinal studies have been conducted to classify the phenotypes of childhood asthma, on the basis of the symptoms, triggers of wheezing illness, or pathophysiological features of the disease. These studies have provided us with important information about the different wheezing phenotypes in young children and about potential mechanisms and risk factors for the development of chronic asthma. The goal of these studies was to provide a better insight into the causes and natural course of childhood asthma. It is well-known that complicated interactions between genes and environmental factors contribute to the development of asthma. Because childhood is a period of rapid growth in both the lungs and the immune system, developmental factors should be considered in the pathogenesis of childhood asthma. The pulmonary system continues to grow and develop until linear growth is completed. Longitudinal studies have reported significant age-related immune development during postnatal early life. These observations suggest that the phenotypes of childhood asthma vary among children and also in an individual child over time. Improved classification of heterogeneous conditions of the disease will help determine novel strategies for primary and secondary prevention and for the development of individualized treatment for childhood asthma.

Bronchopulmonary dysplasia - prevalence, severity and predictive factors in a national cohort of extremely premature infants

AIM

To study prevalence and predictive factors of bronchopulmonary dysplasia (BPD) in a cohort of preterm infants with a high incidence of prenatal steroid and surfactant treatment.

METHODS

BPD was analysed in a national cohort of infants with gestational age (GA) of 22-27 completed weeks (wks) or birth weight (BW) of 500-999 g. Of 464 infants who were transferred to a NICU, 377 infants with GA ≤ 30 wks and survived beyond 28 days were included in the study.

RESULTS

Moderate or severe BPD was strongly related to GA. Of infants with GA 22-25 wks, 67.3% developed BPD compared to 36.6% at GA 26-30 wks. Overall, moderate and severe BPD was significantly more common in boys (63.3%) than in girls (36.6%) (p = 0.0004), but female gender was not a protective factor in infants with GA 22-25 wks. In multivariate analyses, BPD was significantly associated with gender, surfactant treatment and treatment for PDA.

CONCLUSIONS

BPD remains a severe complication of extreme prematurity in spite of prenatal steroids and surfactant treatment. Whether associations with surfactant and PDA treatment simply reflect severity of early lung disease or have causal relationships should probably be studied in randomized controlled trials.

Interleukin-9 polymorphism in infants with respiratory syncytial virus infection: an opposite effect in boys and girls

The predominance of severe respiratory syncytial virus (RSV) bronchiolitis in boys compared to girls is well known, but its mechanism is not yet understood. This is the first study focusing on gender-specific genetic factors affecting the risk of severe RSV infection using a previously described cohort. We determined 347 single-nucleotide polymorphisms (SNPs) in 470 children hospitalized for RSV infection, their parents, and 1,008 random population controls. We tested if these SNPs exerted a different effect in boys and girls by performing statistical interaction tests. Only one SNP (rs2069885) had a gender-specific significant association with RSV infection, severe enough to require hospitalization (P-value 0.00057). The major allele of this structural polymorphism in the interleukin (IL)-9 gene is associated with an increased susceptibility to severe RSV infection in boys, while there is a decreased susceptibility in girls. Haplotype analysis of two SNPs in the IL-9 gene (rs2069885 and rs1799962) showed overrepresentation of the TT haplotype in girls with severe RSV bronchiolitis requiring hospitalization indicating that this is the haplotype conferring the highest risk in girls. In conclusion, the IL-9 genetic polymorphism (rs2069885) has an opposite effect on the risk of severe RSV bronchiolitis in boys and girls. Although so far a difference in IL-9 production in boys and girls has not been reported, this study may help in explaining the different risks of severe RSV bronchiolitis in boys and girls.

[Asthma: a disease of the whole bronchial tree]

Inflammation and remodelling are constant features of asthma. They are present throughout the whole bronchial tree, even in the small airways (less than 2 mm). The inflammatory cell infiltrate and structural changes are, in most cases, identical. However, in severe asthma, nocturnal asthma and fatal asthma, the cellular infiltrate in the distal airways is more intense and the number of activated cells is increased. In fatal asthma there are major alterations in the distal airways involving the smooth muscle and the bronchial epithelium, and mucus hypersecretion leading to distal airway plugging. Thus the histopathological changes in the distal airways contribute to the most severe stages of asthma and should be targeted by treatment. Currently the non-invasive tools that reflect inflammation are unable to assess these changes in the distal airways.

Non-linear and gender-specific relationships among placental growth measures and the fetoplacental weight ratio

GOALS

Fetal growth depends on placental growth; the fetoplacental weight ratio (FPR) is a common proxy for the balance between fetal and placental growth. Male and female infants are known to have differing vulnerabilities in fetal life, during parturition and in infancy. We hypothesized that these differences may be paralleled by differences in how birth weight (BW) and the fetoplacental weight ratio (FPR) are affected by changes in placental proportions.

MATERIALS AND METHODS

Placental proportion measures (disk shape, larger and smaller chorionic diameters, chorionic plate area calculated as the area of an ellipse with the 2 given diameters, disk thickness, cord eccentricity and cord length) were available for 24,601 participants in the Collaborative Perinatal Project delivered between >34 and <43 completed weeks. The variables were standardized and entered into multiple automated regression splines (MARS 2.0, Salford Systems, Vista CA) to identify nonlinearities in the relationships of placental growth measures to BW and FPR with results compared for male and female infants.

RESULTS

Changes in chorionic plate growth in female compared to male infants resulted in a greater change in BW and FPR. The positive effects of umbilical cord length on BW reversed at the mean umbilical cord length in females and at +0.08 SD in male infants.

CONCLUSIONS

Female infants' BW and FPR are each more responsive to changes in placental chorionic plate growth dimensions than males; this may account for greater female resilience (and greater male vulnerability) to gestational stressors. The effect of umbilical cord length on FPR may be due to longer cords carrying greater fetal vascular resistance. Again male fetuses show a higher "threshold" to the negative effects of longer cords on FPR.

Physiology of the small airways: A gender difference?

Small airways are affected in asthma, but gender differences have not been investigated. This study aims to assess whether gender differences exist in the extent of small airway involvement in asthma. Sixteen patients with mild-to-moderate asthma (seven males, median (range) age 39 (19-56) years, FEV(1)%predicted 89% (62-120), PC(20) Methacholine (MCh) 0.4 mg/mL (0.1-4.2)) participated in the study. MCh-induced air trapping at end-expiratory CT scans, alveolar and bronchial exhaled Nitric Oxide (eNO), Single-Breath N(2) closing volume, FEF(25-75%), FEF(50%) and % change in FVC at PC(20) adenosine-5'-monophosphate (AMP) and at PC(20)MCh were evaluated. Multiple regression analyses evaluated whether gender, body mass index and age were explanatory variables for the severity of air trapping. Males had significantly larger MCh-induced increases in low attenuation areas on CT than females, 6% (1-9) versus 2% (-1-7), p=0.012. Males had significantly more signs of MCh-induced air trapping in the non-dependent lung lobes than females. Male gender was the sole factor explaining higher values of MCh-induced signs of air trapping. Females had higher bronchial eNO values than males, 4 nL/s (2-7) versus 2 nL/s (1-4), p=0.04. Small airway involvement in asthma as reflected by MCh-induced air trapping at CT was significantly larger in males than females even in this relatively small group. Bronchial eNO, reflecting partially small airway inflammation, was higher in females than males. These data suggest that the small airways are affected differently in males and females with asthma. Males exhibit small airway involvement by attenuated small airway patency and females by small airway inflammation.

The effects of tobacco smoke exposure on respiratory health in school-aged children

The effects of tobacco smoke exposure on the respiratory health of school-aged children relate to persisting effects of exposure to tobacco smoke during pregnancy and early infancy, passive exposure to environmental tobacco smoke in the home and elsewhere, and active smoking during later childhood. Much of the current evidence comes from cross-sectional and longitudinal observational studies and suggests that, for asthma and pulmonary function outcomes, the strongest associations are with smoke exposure in pregnancy and early childhood, although independent effects of later exposure are reported. Exposure in later childhood to environmental tobacco smoke is associated with increased respiratory symptoms, although for some of these, the effect appears to diminish with increasing age of the child. There is currently a paucity of evidence on the long-term adverse respiratory consequences of active smoking by children and adolescents, but such evidence there is suggests that these may be substantial.

Vermindering van diagnostiek en overbehandeling bij RS-virus-bronchiolitis na geprotocolleerde behandeling

Doel: Evalueren of invoering van een protocol ’Diagnostiek en behandeling van RS-virus-bronchiolitis’ leidt tot minder thoraxfoto’s, minder C-reactieve proteïne (CRP-) en leukocytenbepalingen en minder antibioticavoorschriften bij opgenomen kinderen met respiratoir syncytieel (RS-)bronchiolitis

Opzet: Retrospectieve ‘vóór-ná’-cohortstudie.

Plaats: Canisius-Wilhelmina Ziekenhuis, Nijmegen

Patiënten: Opgenomen kinderen met bewezen RS-virusinfectie

Methoden: Het protocol, met duidelijke restricties voor wat betreft het maken van een thoraxfoto en het bepalen van CRP en leukocyten, werd in februari 2003 ingevoerd. Data van kinderen met RSvirusinfectie opgenomen in de periode 1997 t/m 1999 (cohort A) werden vergeleken met die van kinderen opgenomen van 2003 t/m april 2006 (cohort B).

Resultaten: Cohort A omvatte 155 kinderen en cohort B 170. Na invoering van het protocol nam het aantal CRP- en leukocytenbepalingen af met respectievelijk 49,0% en 48,2% (beide p<0,001) en het aantal thoraxfoto’s met 30,3% (p=0,020). Antibioticatoediening nam af met 55% (p<0,001). De kans op het krijgen van antibiotica nam significant toe zodra een thoraxfoto werd gemaakt (OR=5,2), een CRP-bepaling werd gedaan (OR=5,4) of een leukocytenbepaling werd verricht (OR=4,2). De mediane opnameduur nam na invoering van het protocol significant af van 8,0 naar 6,0 dagen (p<0,001; range 1-13 dagen en 2-23 dagen, respectievelijk). Het verrichten van CRP- en leukocytenbepalingen, het maken van een thoraxfoto of antibioticatoediening hadden geen significante invloed op de opnameduur.

Conclusie: Invoering van het protocol leidde tot significante afname van het aantal thoraxfoto’s, CRP- en leukocytenbepalingen en antibioticavoorschriften. Onze gegevens ondersteunen een restrictief beleid met betrekking tot het verrichten van thoraxfoto’s, CRP- en leukocytenbepalingen bij in het ziekenhuis opgenomen kinderen met RS-virus-bronchiolitis

Alveoli increase in number but not size from birth to adulthood in rhesus monkeys

Postnatal developmental stages of lung parenchyma in rhesus monkeys is about one-third that of humans. Alveoli in humans are reported to be formed up to 8 yr of age. We used design-based stereological methods to estimate the number of alveoli (N(alv)) in male and female rhesus monkeys over the first 7 yr of life. Twenty-six rhesus monkeys (13 males ranging in age from 4 to 1,920 days and lung volumes from 41.7 to 602 cm(3), 13 females ranging in age from 22 to 2,675 days and lung volumes from 43.5 to 380 cm(3)) were necropsied and lungs fixed, isotropically oriented, fractionated, sampled, embedded, and sectioned for alveolar counting. Parenchymal, alveolar, alveolar duct core air, and interalveolar septal tissue volumes increased rapidly during the first 2 yr with slowed growth from 2 to 7 yr. The rate of change was greater in males than females. N(alv) also showed consistent growth throughout the study, with increases in N(alv) best predicted by increases in lung volume. However, mean alveolar volume showed little relationship with age, lung volume, or body weight but was larger in females and showed a greater size distribution than in males. Alveoli increase in number but not volume throughout postnatal development in rhesus monkeys.

Genome wide responses of murine lungs to dietary alpha-tocopherol

Alpha-tocopherol (alpha-T) may affect biological processes by modulating mRNA concentrations. This study screened the responses of approximately 15,000 lung mRNAs to dietary alpha-T in mice. The lung was chosen as the target organ because it is subjected to cyclical variations in oxidant and inflammatory stressors and alpha-T has been implicated in their modulations. The analysis identified approximately 400 mRNAs sensitive to alpha-T status of lungs determined by dietary alpha-T. The female lung transcriptome appears to be more sensitive to the alpha-T status than that of the male lungs. Here, we focus on the induction of 13 cytoskeleton genes by dietary alpha-T because they were similarly induced in the male and the female lungs. Their inductions were confirmed by quantitative-real-time-polymerase chain reaction (qRT-PCR). Immunohistochemical analyses of three of the encoded proteins suggest that they are expressed in lung vasculature and alveolar regions. The data suggest that the lung alpha-T status may modulate cytoarchitecture of lungs.

Predicting adult asthma in childhood

PURPOSE OF REVIEW

There still is no cure for asthma. Early identification of patients at risk for disease progression may lead to better treatment opportunities and hopefully better disease outcomes in adulthood. Recent literature on childhood risk factors associated with the outcome of asthma in adulthood is reviewed.

RECENT FINDINGS

The role of sex and smoking on the outcome of childhood asthma is still uncertain. Better lung function in childhood is consistently associated with better prognosis in adulthood, whereas the severity of bronchial hyperresponsiveness is not a good predictor of asthma outcome. Childhood atopy is associated with the persistence of symptoms but not with lung function in adulthood. An important finding is that anti-inflammatory treatment can reduce the accelerated decline in forced expiratory volume in 1 s and airway remodelling, but there is considerable variety in treatment response between individuals, which possibly can be explained by genetic make-up. Although many studies have investigated the genetics of asthma susceptibility, longitudinal studies on genes associated with asthma outcome are scarce.

SUMMARY

Despite many high-quality investigations, accurate prediction of adult asthma in childhood is still not feasible. Future studies should focus on associations between genetic background and asthma prognosis as an important area of research with great potential.

Gender differences in respiratory symptoms in 19-year-old adults born preterm

Objective

To study the prevalence of respiratory and atopic symptoms in (young) adults born prematurely, differences between those who did and did not develop Bronchopulmonary Disease (BPD) at neonatal age and differences in respiratory health between males and females.

Methods

Design: Prospective cohort study.

Setting: Nation wide follow-up study, the Netherlands.

Participants: 690 adults (19 year old) born with a gestational age below 32 completed weeks and/or with a birth weight less than 1500 g. Controls were Dutch participants of the European Community Respiratory Health Survey (ECRHS).

Main outcome measures: Presence of wheeze, shortness of breath, asthma, hay fever and eczema using the ECRHS-questionnaire

Results

The prevalence of doctor-diagnosed asthma was significantly higher in the ex-preterms than in the general population, whereas eczema and hay fever were significant lower. Women reported more symptoms than men. Preterm women vs controls: asthma 13% vs 5% (p < 0.001); hay fever 8% vs 20% (p < 0.001); eczema 10% vs 42% (p < 0.001). Preterm men vs controls: asthma 9% vs 4% (p = 0.007); hay fever 8% vs 17% (p = 0.005); eczema 9% vs 31% (p < 0.001) Preterm women reported more wheeze and shortness of breath during exercise (sob) than controls: wheeze 30% vs 22% (p = 0.009); sob 27% vs 16% (p < 0.001); 19-year-old women with BPD reported a higher prevalence of doctor diagnosed asthma compared to controls (24% vs 5% p < 0.001) and shortness of breath during exercise (43% vs 16% p = 0.008). The prevalence of reported symptoms by men with BPD were comparable with the controls.

Conclusion

Our large follow-up study shows a higher prevalence of asthma, wheeze and shortness of breath in the prematurely born young adults. 19-year-old women reported more respiratory symptoms than men. Compared to the general population atopic diseases as hay fever and eczema were reported less often.

Effects of viral respiratory infections on lung development and childhood asthma

Viral infections are closely linked to wheezing in infancy, and those children with recurrent virus-induced wheezing episodes are at great risk for chronic childhood asthma. Infancy is a time of increased susceptibility to viral infections, and this stage is also characterized by pulmonary alveolar multiplication and extensive remodeling of the airways to accommodate growth. This coincidence, together with the observation that children with asthma can have structural lung changes and functional deficits at an early age, suggests that viral infections could adversely affect lung development. Inflammatory mediators induced by viral infection are known to have effects on the remodeling process, suggesting a plausible mechanism to support this theory. Furthermore, animal models of viral infection during lung growth and development suggest that developmental factors are important in determining the consequences of infection on long-term lung function. Greater understanding of the effects of viral infections on lung development and growth in early childhood might lead to the discovery of additional strategies for the prevention of recurrent wheezing and chronic asthma.