Respiratory Symptoms In Infants Research Articles

Impact of Postpartum Influenza Vaccination of Mothers and Household Contacts in Preventing Febrile Episodes, Influenza-like Illness, Healthcare Seeking, and Administration of Antibiotics in Young Infants During the 2012-2013 Influenza Season

Influenza is associated with an increased risk for serious illness, hospitalization, and mortality in infants aged <6 months. However, influenza vaccines are not licensed for administration in this age group. The study evaluated the effectiveness of postpartum influenza vaccination of mothers and household members in infants. The influenza vaccine was offered to mothers and household members of neonates born or hospitalized in 3 hospitals prior to the 2012-2013 season. Mothers were contacted every 2 weeks during the influenza season, and data regarding the onset of fever and/or respiratory symptoms in infants, healthcare seeking, hospitalization, and administration of antibiotics were collected. The study group consisted of 553 mothers who delivered 573 neonates. The influenza vaccine was administered to 841 of 1844 (45.6%) household contacts. Vaccination coverage rates ranged between 41.9% for neonates siblings and 49% for mothers. Five hundred thirty infants were analyzed for vaccine effectiveness. For outcomes in the infant, postpartum maternal vaccination had 37.7% effectiveness against acute respiratory illness (ARI), 50.3% against a febrile episode, 53.5% against influenza-like illness (ILI), 41.8% against related healthcare seeking, and 45.4% against administration of antibiotics. Multiple logistic regression analyses showed that maternal influenza vaccination was significantly associated with a decreased probability for febrile episodes, ARIs, and/or ILIs in infants, related healthcare seeking, and/or administration of antibiotics during the influenza season. Vaccination of other household contacts had no impact. Maternal postpartum vaccination against influenza was associated with a significant reduction of influenza-related morbidity, healthcare seeking, and antibiotic prescription in infants during the influenza season.

The Efficacy of the Upright Position on Gastro-Esophageal Reflux and Reflux-Related Respiratory Symptoms in Infants With Chronic Respiratory Symptoms

PurposeGastro-esophageal reflux (GER), particularly non-acid reflux, is common in infants and is a known cause of chronic respiratory symptoms in infancy. Recent guidelines recommended empirical acid suppression therapy and the head-up position in patients with suspected GER. However, the efficacy of the upright position in relieving GER and reflux-related respiratory symptoms in infants is unclear. We conducted this study to investigate the efficacy of the upright position on GER and reflux-related respiratory symptoms in infants with chronic respiratory symptoms.MethodsThirty-two infants (21 male; median age, 5 months; range, 0 to 19 months) with unexplained chronic respiratory symptoms underwent multi-channel intraluminal esophageal impedance and pH monitoring. We retrospectively compared the frequencies of GER and reflux-related symptoms according to body position.ResultsA mean of 3.30 episodes of reflux per hour was detected. Overall, refluxes were more frequent during the postprandial period than the emptying period (3.77 vs. 2.79 episodes/hour, respectively; P=0.01). Although there was no significant difference in the total refluxes per hour between the upright and recumbent positions (6.12 vs. 3.77 episodes, P=0.10), reflux-related respiratory symptoms per reflux were significantly fewer in infants kept in an upright position than in a recumbent position during the postprandial period (3.07% vs. 14.75%, P=0.016). Non-acid reflux was the predominant type of reflux in infants, regardless of body position or meal time.ConclusionsThe upright position may reduce reflux-related respiratory symptoms, rather than reflux frequency. Thus, it may be a useful non-pharmacological treatment for infantile GER disease resistant to acid suppressants.

PRENATAL ENVIRONMENTAL EXPOSURE, SUPPLEMENTATION WITH OMEGA-3 FATTY ACIDS DURING PREGNANCY AND RESPIRATORY SYMPTOMS IN INFANT FROM CUERNAVACA, MEXICO

Background and aims: Maternal consumption of omega 3 polyunsaturated fatty acid can to act as an adjuvant in the immune system and have effects on the neonatal inflammatory response. We conducted the present study to investigate the effect of prenatal docosahexaenoic acid (DHA) supplementation on respiratory symptoms and to identify the main prenatal environmental risk factors for these symptoms in infants. Methods: We included 784 infants whose mothers were randomly assigned to receive daily supplement of 400 mg of DHA or placebo from week 18-22 of pregnancy until childbirth. During pregnancy we collect information on sociodemographics characteristics, past health history, maternal stress and environmental exposures. Also, we collected blood samples to determine maternal specific IgE levels in plasma. Child respiratory symptoms information was collected using a recall questionnaire at 1, 3, 6, 9, 12 and 18 months of age. Poisson regression models were used to identify the main prenatal risk factors for respiratory symptoms. Results: The occurrence of respiratory symptoms did not differ significantly between groups; however, the occurrence of a combined measure of some symptoms was lower in the DHA group. We observed that the higher risk of respiratory symptoms were for the children whose mothers were randomly assigned to receive placebo. The main risks factors were use pesticides in home (OR= 1.18; 95%IC 1.08, 1.29) gender male (OR= 1.09; 95% CI 1.01, 1.18) and maternal atopy (OR= 1.03 95%CI 0.95, 1.12). Conclusions: DHA supplementation during pregnancy decreased the occurrence of respiratory symptoms in infants and this study strengthens the evidence that the family history and prenatal environmental exposure in early stages of life increase the risk of respiratory symptoms in childhood.

Urban land-use and respiratory symptoms in infants

Background Children's respiratory health has been linked to many factors, including air pollution. The impacts of urban land-use on health are not fully understood, although these relationships are of key importance given the growing populations living in urban environments. Objectives We investigated whether the degree of urban land-use near a family's residence is associated with severity of respiratory symptoms like wheeze among infants. Methods Wheeze occurrence was recorded for the first year of life for 680 infants in Connecticut for 1996–1998 from a cohort at risk for asthma development. Land-use categories were obtained from the National Land Cover Database. The fraction of urban land-use near each subject's home was related to severity of wheeze symptoms using ordered logistic regression, adjusting for individual-level data including smoking in the household, race, gender, and socio-economic status. Nitrogen dioxide (NO 2) exposure was estimated using integrated traffic exposure modeling. Different levels of urban land-use intensity were included in separate models to explore intensity-response relationships. A buffer distance was selected based on the log-likelihood value of models with buffers of 100–2000 m by 10 m increments. Results A 10% increase in urban land-use within the selected 1540 m buffer of each infant's residence was associated with 1.09-fold increased risk of wheeze severity (95% confidence interval, 1.02–1.16). Results were robust to alternate buffer sizes. When NO 2, representing traffic pollution, was added to the model, results for urban land-use were no longer statistically significant, but had similar central estimates. Higher urban intensity showed higher risk of prevalence and severity of wheeze symptoms. Conclusions Urban land-use was associated with severity of wheeze symptoms in infants. Findings indicate that health effect estimates for urbanicity incorporate some effects of traffic-related emissions, but also involve other factors. These may include differences in housing characteristics or baseline healthcare status.

Prolonged bedtime bottle feeding and respiratory symptoms in infants

BackgroundInfants with chronic respiratory symptoms should be evaluated thoroughly because there are various causes which are different from those of children and adolescents.ObjectiveThis study was designed to investigate the relationship between chronic respiratory symptoms and bedtime bottle feeding in infants after the age of 6 months.MethodsWe conducted a prospective study that included 44 infants who presented with respiratory symptoms for more than 8 weeks and also had been bottle-fed during bedtime even after 6 months of age. The infants were divided into 2 groups; infants who discontinued bedtime bottle feeding and those who did not. Respiratory symptom scores were graded with a four-point scale at 0, 1, 2 and 3 months, and were compared between the 2 groups.ResultsTwenty eight infants (63.6%) stopped being bottle-fed during bedtime and 16 infants (36.4%) were still bottle-fed. The respiratory symptom scores were significantly decreased in infants who stopped bedtime bottle feeding (p = 0.0003).ConclusionIt is suggested that prolonged bedtime bottle feeding might be one of the causes of chronic respiratory symptoms in infants.

Mannose‐binding lectin cord blood levels and respiratory symptoms during infancy: a prospective birth cohort study

Respiratory infections cause considerable morbidity during infancy. The impact of innate immunity mechanisms, such as mannose‐binding lectin (MBL), on respiratory symptoms remains unclear. The aims of this study were to investigate whether cord blood MBL levels are associated with respiratory symptoms during infancy and to determine the relative contribution of MBL when compared with known risk factors. This is a prospective birth cohort study including 185 healthy term infants. MBL was measured in cord blood and categorized into tertiles. Frequency and severity of respiratory symptoms were assessed weekly until age one. Association with MBL levels was analysed using multivariable random effects Poisson regression. We observed a trend towards an increased incidence rate of severe respiratory symptoms in infants in the low MBL tertile when compared with infants in the middle MBL tertile [incidence rate ratio (IRR) = 1.59; 95% confidence interval (CI): 0.95–2.66; p = 0.076]. Surprisingly, infants in the high MBL tertile suffered significantly more from severe and total respiratory symptoms than infants in the middle MBL tertile (IRR = 1.97; 95% CI: 1.20–3.25; p = 0.008). This association was pronounced in infants of parents with asthma (IRR = 3.64; 95% CI: 1.47–9.02; p = 0.005). The relative risk associated with high MBL was similar to the risk associated with well‐known risk factors such as maternal smoking or childcare. In conclusion the association between low MBL levels and increased susceptibility to common respiratory infections during infancy was weaker than that previously reported. Instead, high cord blood MBL levels may represent a so far unrecognized risk factor for respiratory morbidity in infants of asthmatic parents.

Effectiveness of a nutrition program in reducing symptoms of respiratory morbidity in children: A randomized field trial

Objectives To assess the effectiveness of home visits advising mothers about breast feeding and weaning in reducing symptoms of respiratory morbidity at the age of 12 months. Methods A randomized field trial was conducted with mothers who gave birth within the public health system in the Brazilian city of Sao Leopoldo (2001/2002). The intervention group received dietary advice during the first year based on a Brazilian national health policy for primary care, which is based on WHO guidelines. Morbidity data was assessed in 397 children at 12 months. Results A total of 23.3% of the children in the intervention group and 39.7% of the controls had one or more of the following symptoms during the month preceding assessment: cough, stuffy nose, runny nose, or breathlessness. The risk of respiratory morbidity symptoms was 41% lower for the intervention group (RR: 0.59; 95% CI: 0.43–0.81). The number of families needed to be visited to avoid one children presenting symptoms of respiratory morbidity (Number Needed to Treat) was 6.1. The intervention-group status was also associated with a longer duration of exclusive (RR:1.59; 95% CI: 1.21–2.07; p = 0.001) and total breastfeeding (RR: 1.25; 95% CI:1.02–1.55; p = 0.032) later introduction of solid foods (RR:1.11; 95% CI: 1.02–1.21; p = 0.023), and a lower proportion of current medication use (RR:0.56; 95% CI:0.34–0.91; p = 0.016). Conclusion A nutrition education program during the first year of life has a positive impact on reducing respiratory symptoms in infants.

Impaired Lung Homeostasis in Neonatal Mice Exposed to Cigarette Smoke

In infants, smoke exposure is associated with more respiratory illnesses and decreased lung function. We hypothesized that perinatal lung is particularly susceptible to the damaging effects of cigarette smoke (CS) and that exposure to CS during this period may alter expression of immune response genes and adversely affect lung growth. To test this, we exposed neonatal mice to 14 days of CS. Immediately after exposure to CS, pulmonary gene expression profiling was performed on 2-week-old CS-exposed lung and age-matched control lung. Nitrotyrosine, TUNEL, MAC3, and phospho-SMAD-2 (p-SMAD2) staining was also performed. At 8 weeks of age, lung volume measurements were determined and mean linear intercept measurements were calculated. Pulmonary gene expression profiling revealed that CS exposure significantly inhibited type 1 and type 2 interferon pathway genes in neonatal lung, compared with age-matched control lung. Neonatal CS-exposed lung also had a significant increase in n-tyrosine, TUNEL, and p-SMAD2 staining when compared with adult CS-exposed lung and age-matched control lung. Lung volumes at 8 weeks of age were modestly but significantly decreased in mice exposed to CS in the neonatal period compared with age-matched controls, consistent with impaired lung growth. The results of this study indicate that exposure to CS during the neonatal period inhibits expression of genes involved in innate immunity and mildly impairs postnatal lung growth. These findings may in part explain the increased incidence of respiratory symptoms in infants and children exposed to CS.

Congenital vascular rings: a rare cause of respiratory distress in infants and children

Congenital vascular rings may often cause unexplained respiratory symptoms in infants and young children. Their diagnosis and treatment are often delayed. Few studies of vascular rings have been reported in China. The aim of this study was to describe the clinical presentation, diagnosis and surgical management of infants and children with congenital vascular rings. Clinical histories, physical examinations, investigations, image studies and surgical interventions were retrospectively evaluated in 7 children (age range: 2 months-4 years, mean 7 months) with congenital vascular rings. Chest radiography was performed in all patients. Echocardiography and computed tomography (CT) with 3-dimensional (3D) reconstructions were performed in 6 patients. Esophagography, cardiac catheterization and angiography, and bronchoscopy were performed in 1, 1 and 4 children, respectively. Six of the 7 patients had respiratory symptoms, including recurrent cough, stridor and wheeze. Age at onset of symptoms ranged from 1 month to 11 months. Chest X-ray showed nothing important on the vascular rings, besides bronchitis and pneumonia. Contrast-enhanced CT diagnosed vascular rings in 6 patients. Four patients had double aortic arches, two had balanced arches and two were right arch dominant. One patient had a right aortic arch with left ligament and 1 patient had a pulmonary artery sling. Echocardiography failed to diagnose vascular rings in 2 patients. The esophagogram of 1 patient showed esophageal compression. Bronchoscopy of 4 patients showed compression of the distal trachea. Five of the 7 patients underwent surgical division of the vascular rings. Surgical observation confirmed the CT findings in each patient. Patients, especially infants or young children, with recurrent respiratory symptoms such as chronic cough, stridor and wheeze, should be examined for the possible presence of congenital vascular rings. Contrast-enhanced CT can clearly show the anatomy of vascular rings. As a noninvasive technique, echocardiography is helpful for diagnosis. Early surgical management in symptomatic patients is effective.

Respiratory symptoms among infants at risk for asthma: association with surfactant protein A haplotypes

BackgroundWe examined the association between single nucleotide polymorphisms (SNPs) in loci encoding surfactant protein A (SFTPA) and risk of wheeze and persistent cough during the first year of life among a cohort of infants at risk for developing asthma.MethodsBetween September 1996 and December 1998, mothers of newborn infants were invited to participate if they had an older child with clinician-diagnosed asthma. Each mother was given a standardized questionnaire within 4 months of her infant's birth. Infant respiratory symptoms were collected during quarterly telephone interviews at 6, 9 and 12 months of age. Due to the association of SFTPA polymorphisms and race/ethnicity, analyses were restricted to 221 white infants for whom whole blood and respiratory data were available. Ordered logistic regression models were used to examine the association between respiratory symptom frequency and SFTPA haplotypes.ResultsThe 6A allele haplotype of SFTPA1, with an estimated frequency of 6% among our study infants, was associated with an increased risk of persistent cough (OR 3.69, 95% CI 1.71, 7.98) and wheeze (OR 4.72, 95% CI 2.20, 10.11). The 6A/1A haplotype of SFTPA, found among approximately 5% of the infants, was associated with an increased risk of persistent cough (OR 3.20, 95% CI 1.39, 7.36) and wheeze (OR 3.25, 95% CI 1.43, 7.37).ConclusionPolymorphisms within SFTPA loci may be associated with wheeze and persistent cough in white infants at risk for asthma. These associations require replication and exploration in other ethnic/racial groups.

Association of Household Mold With Peak Expiratory Flow Rate Variability in Asthmatic Children

TAB3-PD-05 Introduction: Exposure to high household levels of Penicillium is associated with an increased risk of respiratory symptoms in infants at high risk for developing asthma. Variability in peak expiratory flow rate may occur as a result of bronchoconstricting effects of inhaled contaminants and is associated with asthma. We examined the association between exposure to household mold and peak expiratory flow in asthmatic children 6 to 12 years of age. Methods: A group of 307 asthmatic children participated in a 2-week peak flow monitoring as part of a larger study. At an enrollment visit to the subject's home, airborne mold samples were collected (Burkhard portable sampler using dichloran-18% glycerol agar plates), the use of the peak flow device (Vitalograph) was demonstrated, and the child was instructed to take a peak flow measurement in the morning after waking and in the evening before bedtime every day for 14 days. Mold samples were cultured and fungi genus identified. Peak flow for each child was expressed as an average of daily variability percent mean (VPM) for the monitoring period, ie, mean over days of (daily maximium peak flow − daily minimum peak flow)/(mean of all peak flows). Logistic regression models were used to examine the relationship between mean VPM over 18.5% (75th percentile) and any mold in the home (total mold, Cladosporium, Penicillium, or other). Results: Some mold was detected in 93% of the homes. The most common molds were Cladosporium in 73% and Penicillium in 42% of the samples. One half (53%) of children had 6 or more days of complete peak flow data for the 14-day monitoring period. Controlling for gender, ethnicity, age, and winter season of sampling, any Penicillium measured in the home was associated with mean VPM over 18.5% (OR = 2.4; 95% CI, 1.2–4.8). Greater peak flow variability was not associated with total mold, Cladosporium, or other mold measured in the home. Discussion and Conclusions: One limitation of the study is that compliance with peak flow instructions was poor: half of the children had complete peak flow data for less than half of the monitoring period days. Exposure to Penicillium in the home may have a negative impact on lung function in asthmatic children as measured by greater variability in peak flow.

Adverse effects of maternal smoking during pregnancy on innate immunity in infants

The potentially fatal effects of maternal smoking on infants have been recognised since the 1800s 1. In the latter half of the 1900s, the link between maternal smoking and the increased rate of lower respiratory infection (LRI) in early life was described 2. Given the high rates of smoking in many societies 3, the burden of the increase in LRI is substantial. In a meta-analysis of relationships between parental smoking and respiratory disease, Li et al. 4 calculated that the odds ratio (OR) for hospitalisation of LRI in infancy or early childhood for those exposed to parental environmental tobacco smoke (ETS) compared with those not exposed was 1.93 (95% confidence interval (CI) 1.66–2.25). The risk was age related, as the ORs of prevalence of serious LRI were 1.71 (95% CI 1.33–2.20) and 1.25 (95% CI 0.88–1.78) for children aged 0–2 and 3–6 yrs, respectively. Li et al. 4 concluded that the results of community and hospital studies were broadly consistent, and showed that the child of a parent who smokes is at approximately twice the risk of having a serious respiratory tract infection requiring hospitalisation in early life. Indeed, early respiratory infection is not only a major cause of morbidity in developed countries, but, in developing countries, respiratory infection is also the leading cause of death in children 5. There have been a large number of studies showing the relationships between maternal smoking and impaired lung function and increases in respiratory symptoms in infants and young children. An effect of maternal smoking on neonatal lung function has been demonstrated in a study …

Association of surfactant protein A polymorphisms with otitis media in infants at risk for asthma

BackgroundOtitis media is one of the most common infections of early childhood. Surfactant protein A functions as part of the innate immune response, which plays an important role in preventing infections early in life. This prospective study utilized a candidate gene approach to evaluate the association between polymorphisms in loci encoding SP-A and risk of otitis media during the first year of life among a cohort of infants at risk for developing asthma.MethodsBetween September 1996 and December 1998, women were invited to participate if they had at least one other child with physician-diagnosed asthma. Each mother was given a standardized questionnaire within 4 months of her infant's birth. Infant respiratory symptoms were collected during quarterly telephone interviews at 6, 9 and 12 months of age. Genotyping was done on 355 infants for whom whole blood and complete otitis media data were available.ResultsPolymorphisms at codons 19, 62, and 133 in SP-A1, and 223 in SP-A2 were associated with race/ethnicity. In logistic regression models incorporating estimates of uncertainty in haplotype assignment, the 6A4/1A5haplotype was protective for otitis media among white infants in our study population (OR 0.23; 95% CI 0.07,0.73).ConclusionThese results indicate that polymorphisms within SP-A loci may be associated with otitis media in white infants. Larger confirmatory studies in all ethnic groups are warranted.

Association of Surfactant Protein a Polymorphisms with Respiratory Symptoms in Infants

Association of Surfactant Protein a Polymorphisms with Respiratory Symptoms in Infants

Low-Level Ozone Exposure and Respiratory Symptoms in Infants

ObjectiveRecent studies indicate that the U.S. Environmental Protection Agency (EPA) ozone standards may not protect sensitive individuals. In this study we examined respiratory effects of ozone in infants who may be vulnerable, particularly if they are children of asthmatic mothers.DesignWomen delivering babies at one of five hospitals in southwestern Virginia between 1994 and 1996 were invited to participate in a cohort study; 780 women enrolled. Ambient air quality data (ozone and particulate matter) were collected at a central monitoring site.ParticipantsThis analysis is of 691 infants followed for approximately 83 days between 10 June and 31 August 1995 and/or 1996; they contributed a total of 52,421 infant-days of follow-up. Mothers were interviewed at enrollment and approximately biweekly to report infants’ daily symptoms. Repeated measures logistic regression models were run separately for wheeze, difficulty breathing, and cough. Ozone metrics included 24-hr average, peak 1-hr, and maximum 8-hr average. Analyses were repeated for the 61 infants whose mothers had asthma.ResultsFor every interquartile-range increase in same-day 24-hr average ozone, likelihood of wheeze increased 37% [95% confidence interval (CI), 2–84%]. Among infants of asthmatic mothers, same-day 24-hr average ozone increased likelihood of wheeze 59% (95% CI, 1–154%) and of difficulty breathing 83% (95% CI, 42–136%). Maximum 8-hr ozone and peak 1-hr ozone were associated with difficulty breathing, but not wheeze, in infants of asthmatic mothers. Ozone was not associated with cough.ConclusionsAt levels of ozone exposure near or below current U.S. EPA standards, infants are at increased risk of respiratory symptoms, particularly infants whose mothers have physician-diagnosed asthma.

Association of early‐onset otitis media in infants and exposure to household mould

Otitis media is one of the most common infections of early childhood. Children who first experience acute otitis media at an early age (before 6 months) are at increased risk for recurrent otitis media. This prospective study investigated exposure to measured levels of airborne household mould and the risk of early otitis media in the first 6 months of life among a cohort of infants at high risk for asthma. Between September 1996 and December 1998, women were invited to participate if they had at least one other child with physician-diagnosed asthma. Mothers were given a standardised questionnaire within 4 months of their infant's birth. Airborne mould samples were also taken at this time, and culturable fungi were categorised into four levels according to the report of the Commission of European Communities: 0 (undetectable), 1-499 colony forming units (CFU)/m(3) (low), 500-999 CFU/m(3) (medium), > or =1000 CFU/m(3) (high). Infant respiratory symptoms were collected during quarterly telephone interviews at 6, 9 and 12 months of age. Of the 806 children in the study, 27.8% experienced otitis media before six months of age. Household levels of Penicillium and Cladosporium were modestly associated with the number of otitis media episodes (P = 0.056 and 0.081 respectively). After controlling for potential confounders, Penicillium and Cladosporium were not associated with early otitis media. High levels of 'other' mould (defined as total spore count minus counts for Penicillium, Cladosporium, and yeast) were associated with early otitis media (OR 3.49; 95% CI [1.38, 8.79]). We also found associations between day-care outside of the home and birth during the summer or fall season with early otitis media. This study is suggestive of a relationship between otitis media and mould that warrants further study.

A parent completed questionnaire to describe the patterns of wheezing and other respiratory symptoms in infants and preschool children

Aim: To develop a standardised and validated respiratory symptom questionnaire for use in epidemiological or follow up studies in infants and preschool children. Methodology: After initial design and development, the...

Infant respiratory symptoms associated with indoor heating sources.

This study examined the effects of indoor heating sources on infant respiratory symptoms during the heating season of the first year of life. Mothers delivering babies between 1993 and 1996 at 12 hospitals in Connecticut and Virginia were enrolled. Daily symptom and heating source use information about their infant was obtained every 2 weeks during the first year of life. Heating sources included fireplace, wood stove, kerosene heater, and gas space heater use. Four health outcomes were analyzed by reporting period: days of wheeze, episodes of wheeze, days of cough, and episodes of cough. A large percentage of infants had at least one episode of cough (88%) and wheeze (33%) during the heating season of the first year of life. Wood stove, fireplace, kerosene heater, and gas space heater use was intermittent across the study period. In adjusted Poisson regression models controlling for important confounders, gas space heater use was associated with episodes and days of wheeze. Wood stove use was associated with total days of cough, and kerosene heater use was associated with episodes of cough. Fireplace use was not associated with any of the respiratory symptoms. Use of some heating sources appears related to respiratory symptoms in infants.

Lung function at one month of age as a risk factor for infant respiratory symptoms in a high risk population

Background: Abnormal premorbid lung function is a risk factor for subsequent wheezing in children with one or no atopic parent. This study was undertaken to establish whether early lung function...

Effect of Nitrogen Dioxide on Respiratory Viral Infection in Airway Epithelial Cells

Nitrogen dioxide (NO2) is a common air pollutant outdoors and indoors in homes with unvented combustion sources. It is also a constituent of tobacco smoke. Epidemiological studies suggest that children exposed to NO2, or living with smoking parents, have an increased incidence of respiratory viral infections. The most common virus causing severe respiratory symptoms in infants and young children is respiratory syncytial virus (RSV). In the present study we investigated whether NO2 exposure affects RSV infection in airway epithelial cells, the host cells for viral replication and virus-induced cytokine production. Cultures of the bronchial epithelial cell line BEAS-2B exposed to 0.5, 1.0, and 1.5 ppm NO2 for 60 min were infected with RSV. Viral replication, as well as RSV-induced interleukin (IL)-6 and IL-8, was assessed at various times postinfection. The NO2 doses used were not toxic to the BEAS-2B cells as measured by release of lactic dehydrogenase (LDH). The internalization of RSV was increased by exposure to 0.5 ppm NO2 and decreased by exposure to 1.5 ppm NO2. On the other hand, the release of infectious virus 48 h postexposure was not affected by the two lower doses of NO2, but was significantly reduced in cells exposed to 1.5 ppm NO2. Virus-induced cytokine production was also significantly reduced in cells exposed to 1.5 ppm NO2, and not affected by 0.5 and 1.0 ppm. It is likely that the decrease in cytokine production is related to the decrease in viral burden. These data suggest that possible increases in viral clinical symptoms associated with NO2 may not be caused by increased susceptibility of the epithelial cells to infection but may result from effects of NO2 on host defenses that prevent the spread of virus.