Early life insults as determinants of chronic obstructive pulmonary disease in adult life

Host, Gender, and Early-Life Factors as Risks for Chronic Obstructive Pulmonary Disease

Although smoking results in lung pathology in many, still not all smokers develop chronic obstructive pulmonary disease (COPD). Roughly a quarter of patients with COPD have never smoked. An understanding of both host and environmental factors beyond smoking that contribute to disease development remain critical to understanding disease prevention and ultimately effectively intervene. In this article, we summarize host factors, including genetics and gender, as well as early-life events that contribute to the development of COPD.

Gestational Exposure to Cigarette Smoke Suppresses the Gasotransmitter H2S Biogenesis and the Effects Are Transmitted Transgenerationally

Rationale: Gestational cigarette smoke (CS) impairs lung angiogenesis and alveolarization, promoting transgenerational development of asthma and bronchopulmonary dysplasia (BPD). Hydrogen sulfide (H₂S), a proangiogenic, pro-alveolarization, and anti-asthmatic gasotransmitter is synthesized by cystathionine-γ-lyase (CSE), cystathionine-β-synthase (CBS), and 3-mercaptopyruvate sulfur transferase (3MST). Objective: Determine if gestational CS exposure affected the expression of H₂S synthesizing enzymes in the mouse lung and human placenta. Methods: Mice were exposed throughout gestational period to secondhand CS (SS) at approximating the dose of CS received by a pregnant woman sitting in a smoking bar for 3 h/days during pregnancy. Lungs from 7-days old control and SS-exposed pups and human placenta from mothers who were either non-smokers or smokers during pregnancy were analyzed for expression of the enzymes. Measurements: Mouse lungs and human placentas were examined for the expression of CSE, CBS, and 3MST by immunohistochemical staining, qRT-PCR and/or Western blot (WB) analyses. Results: Compared to controls, mouse lung exposed gestationally to SS had significantly lower levels of CSE, CBS, and 3MST. Moreover, the SS-induced suppression of CSE and CBS in F1 lungs was transmitted to the F2 generation without significant change in the magnitude of the suppression. These changes were associated with impaired epithelial-mesenchymal transition (EMT)-a process required for normal lung angiogenesis and alveolarization. Additionally, the placentas from mothers who smoked during pregnancy, expressed significantly lower levels of CSE, CBS, and 3MST, and the effects were partially moderated by quitting smoking during the first trimester. Conclusions: Lung H₂S synthesizing enzymes are downregulated by gestational CS and the effects are transmitted to F2 progeny. Smoking during pregnancy decreases H₂S synthesizing enzymes is human placentas, which may correlate with the increased risk of asthma/BPD in children.

Asthma-like symptoms in young children increase the risk of COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) may originate in early life and share disease mechanisms with asthma-like symptoms in early childhood. This possibility remains unexplored on account of the lack of long-term prospective studies from infancy to the onset of COPD.

OBJECTIVE

We aimed to investigate the relationship between asthma-like symptoms in young children and development of COPD.

METHODS

In a population-based cohort of women who gave birth at the central hospital in Copenhagen during period from 1959 to 1961, we investigated data from 3290 mother-child pairs who attended examinations during pregnancy and when the children were aged 1, 3, and 6 years. COPD was assessed from the Danish national registries on hospitalizations and prescription medication since 1994. A subgroup of 930 individuals underwent spirometry testing at age 50 years.

RESULTS

Of the 3290 children, 1 in 4 had a history of asthma-like symptoms in early childhood. The adjusted hazard ratio for hospitalization for COPD was 1.88 (95% CI = 1.32-2.68), and the odds ratio for prescription of long-acting muscarinic antagonists was 2.27 (95% CI = 1.38-3.70). Asthma-like symptoms in early childhood were also associated with a reduced FEV₁ percent predicted and an FEV₁-to-forced vital capacity ratio at age 50 years (-3.36% [95% CI = -5.47 to -1.24] and -1.28 [95% CI = -2.17 to -0.38], respectively) and with COPD defined according to Global Initiative for Chronic Obstructive Lung Disease stage higher than 1 (odds ratio = 1.96 [95% CI = 1.13-3.34]).

CONCLUSION

This 60-year prospective follow-up of a mother-child cohort demonstrated a doubled risk for COPD from childhood asthma-like symptoms.

Incidence trends of airflow obstruction among European adults without asthma: a 20-year cohort study

Investigating COPD trends may help healthcare providers to forecast future disease burden. We estimated sex- and smoking-specific incidence trends of pre-bronchodilator airflow obstruction (AO) among adults without asthma from 11 European countries within a 20-year follow-up (ECRHS and SAPALDIA cohorts). We also quantified the extent of misclassification in the definition based on pre-bronchodilator spirometry (using post-bronchodilator measurements from a subsample of subjects) and we used this information to estimate the incidence of post-bronchodilator AO (AOpost-BD), which is the primary characteristic of COPD. AO incidence was 4.4 (95% CI: 3.5-5.3) male and 3.8 (3.1-4.6) female cases/1,000/year. Among ever smokers (median pack-years: 20, males; 12, females), AO incidence significantly increased with ageing in men only [incidence rate ratio (IRR), 1-year increase: 1.05 (1.03-1.07)]. A strong exposure-response relationship with smoking was found both in males [IRR, 1-pack-year increase: 1.03 (1.02-1.04)] and females [1.03 (1.02-1.05)]. The positive predictive value of AO for AOpost-BD was 59.1% (52.0-66.2%) in men and 42.6% (35.1-50.1%) in women. AOpost-BD incidence was 2.6 (1.7-3.4) male and 1.6 (1.0-2.2) female cases/1,000/year. AO incidence was considerable in Europe and the sex-specific ageing-related increase among ever smokers was strongly related to cumulative tobacco exposure. AOpost-BD incidence is expected to be half of AO incidence.

Evolution and Determinants of Lung Function until Late Infancy among Infants Born Preterm

To investigate the evolution of lung function in preterm infants with and without bronchopulmonary dysplasia (BPD) and to determine the perinatal characteristics associated with indexes of lung function in later infancy. Longitudinal lung function assessments were performed at approximately 6, 12, 18, and 24 months of corrected age in preterm infants. Perinatal characteristics were further analyzed to ascertain the determinants of lung function indexes. Although all preterm infants (n = 121; 61 without BPD and 60 with BPD) exhibited decreased lung function in early infancy (6 months of age), after body length was adjusted for, only infants with BPD exhibited poor performance. Furthermore, the lung function of infants with mild to moderate BPD caught up gradually, but the generally poor lung function performance of infants with severe BPD, especially in forced expiratory flow, persisted until later age (24 months). Regarding perinatal characteristics, the z-score of body length at the time of examination and total number of days on positive-pressure ventilation are the major determinants of lung function in later infancy.

The relationship between second-hand smoke and wheezing in infants from Córdoba, Argentina

BACKGROUND

Wheezing constitutes a common respiratory symptom in children, and several risk factors have been associated with the prevalence of recurrent wheezing (RW) and its severity, especially viral respiratory infections and second-hand smoke (SHS) exposure.

OBJECTIVE

To analyze the relationship between smoking patterns in the home and wheezing, in infants from the city of Córdoba, Argentina, during their first year of life.

METHODS

Parents of infants were invited to complete a standardized questionnaire voluntarily and anonymously (WQ-P1-EISL). Wheezing in the first 12 months of life was classified as occasional wheezing (OW) when having one or two episodes during the first 12 months of life; recurrent wheezing (RW) if having three or more, and more frequent wheezing (MFW) ≥6 episodes.

RESULTS

409 infants (39.0%) had one or more episodes of wheezing in the first 12 months. Of these, 214 infants (52.3%) presented occasional wheezing (OW), 135 (33%) had recurrent wheezing (RW), and 60 (14.7%) more frequent wheezing (MFW). SHS was significantly related to MFW, especially if the mother smoked (OR=2.7; IC 95%: 1.4-5.18; p=0.0009) or if she smoked during pregnancy (OR=4; IC 95%: 1.8-8.5; p=0.0001). This group of MFW was also associated with SHS as well as having been to the emergency room for wheezing (40.87%, p=0.0056).

CONCLUSION

The results indicate that second-hand tobacco smoke is a significant risk factor for the presence of wheezing in infants, and for its severity. Our findings have significant implications for public health, as smoking is a modifiable behavior.

Paediatric and adult bronchiectasis: Specific management with coexisting asthma, COPD, rheumatological disease and inflammatory bowel disease

Bronchiectasis, conventionally defined as irreversible dilatation of the bronchial tree, is generally suspected on a clinical basis and confirmed by means of chest high-resolution computed tomography. Clinical manifestations, including chronic productive cough and endobronchial suppuration with persistent chest infection and inflammation, may deeply affect quality of life, both in children/adolescents and adults. Despite many cases being idiopathic or post-infectious, a number of specific aetiologies have been traditionally associated with bronchiectasis, such as cystic fibrosis (CF), primary ciliary dyskinesia or immunodeficiencies. Nevertheless, bronchiectasis may also develop in patients with bronchial asthma; chronic obstructive pulmonary disease; and, less commonly, rheumatological disorders and inflammatory bowel diseases. Available literature on the development of bronchiectasis in these conditions and on its management is limited, particularly in children. However, bronchiectasis may complicate the clinical course of the underlying condition at any age, and appropriate management requires an integration of multiple skills in a team of complementary experts to provide the most appropriate care to affected children and adolescents. The present review aims at summarizing the current knowledge and available evidence on the management of bronchiectasis in the other conditions mentioned and focuses on the new therapeutic strategies that are emerging as promising tools for improving patients' quality of life.

The etiologic origins for chronic obstructive pulmonary disease

COPD, characterized by long-term poorly irreversible airway limitation and persistent respiratory symptoms, has resulted in enormous challenges to human health worldwide, with increasing rates of prevalence, death, and disability. Although its origin was thought to be in the interactions of genetic with environmental factors, the effects of environmental factors on the disease during different life stages remain little known. Without clear mechanisms and radical cure for it, early screening and prevention of COPD seem to be important. In this review, we will discuss the etiologic origins for poor lung function and COPD caused by specific adverse effects during corresponding life stages, as well as try to find new insights and potential prevention strategies for this disease.

Respiratory frequency plasticity during development

Respiratory frequency plasticity is a long-lasting increase in breathing frequency due to a perturbation. Mechanisms underlying respiratory frequency are poorly understood, and there is little evidence of frequency plasticity in neonates. This hybrid review/research article discusses available literature regarding frequency plasticity and highlights potential research opportunities. Also, we include data demonstrating a model of frequency plasticity using isolated neonatal rat brainstem-spinal cord preparations. Specifically, substance P (SubP) application induced a long-lasting (>60 min) increase in spontaneous respiratory motor burst frequency, particularly in brainstem-spinal cords with the pons attached; there were no male/female differences. SubP-induced frequency plasticity is dependent on the application pattern, such that intermittent (rather than sustained) SubP applications induce more frequency plasticity. SubP-induced frequency plasticity was blocked by a neurokinin-1 receptor antagonist. Thus, the newborn rat respiratory control system has the capacity to express frequency plasticity. Identifying mechanisms that induce frequency plasticity may lead to novel methods to safely treat breathing disorders in premature and newborn infants.

Plasma cathelicidin and longitudinal lung function in current and former smokers

INTRODUCTION

Cathelicidin (also known as LL-37 in humans) is an antimicrobial peptide secreted by epithelial and immune cells and regulated by vitamin D. The immunological roles of cathelicidin make it a putative biomarker to identify individuals at risk for reduced lung function. The objective of this study is to determine potential independent associations between low plasma cathelicidin and longitudinal lung function in current or former smokers without COPD.

METHODS

In a nested analysis of 308 participants from an observational cohort study, plasma cathelicidin and serum 25-hydroxy-vitamin D measurements were obtained at baseline, years three and five. The independent association between lowest quartile cathelicidin (<35 ng/ml) and forced-expiratory-volume-in-1-second (FEV1) at baseline, six and 18 months from each cathelicidin measurement was assessed with generalized estimating equations after adjusting for age, sex, race, smoking status and intensity. The long-term stability of cathelicidin and relationship with vitamin D was evaluated.

RESULTS

The cohort was 91% African-American, mean age 48.6 years, 32% female, and 81% current smokers. Participants with low cathelicidin were more likely to be female and have lower FEV1. Low cathelicidin was not independently associated with baseline FEV1. There was an independent association between low cathelicidin and reduced FEV1 at six months [-72 ml (95% CI, -140 to -8ml); p = 0.027] and 18 months [-103 ml (95% CI, -180 to -27 ml); p = 0.007]. Cathelicidin was stable over time and not correlated with vitamin D level.

CONCLUSION

In current and former smokers with preserved lung function, low cathelicidin is associated with sustained lung function reductions at six and 18 months, suggesting that cathelicidin may be an informative biomarker to predict persistent lung function disparities among at-risk individuals.

Bronchopulmonary dysplasia: what are its links to COPD?

Emerging evidence suggests that adverse early life events can affect long-term health trajectories throughout life. Preterm birth, in particular, is a significant early life event that affects approximately 10% of live births. Worldwide, prematurity is the number one cause of death in children less than 5 years of age and has been shown to disrupt normal lung development with lasting effects into adult life. Along with impaired lung development, interventions used to support gas exchange and other sequelae of prematurity can lead to the development of bronchopulmonary dysplasia (BPD). BPD is a chronic respiratory disease of infancy characterized by alveolar simplification, small airways disease, and pulmonary vascular changes. Although many survivors of BPD improve with age, survivors of BPD often have chronic lung disease characterized by airflow obstruction and intermittent pulmonary exacerbations. Long-term lung function trajectories as measured by FEV1 can be lower in children and adults with a history BPD. In this review, we discuss the epidemiology and manifestations of BPD and its long-term consequences throughout childhood and into adulthood. Available evidence suggests that disrupted lung development, genetic susceptibility and subsequent environment and infectious events that occur in prenatal and postnatal life likely increase the predisposition of children with BPD to develop early onset chronic obstructive pulmonary disease (COPD). The reviews of this paper are available via the supplemental material section.