Home and School Pollutant Exposure, Respiratory Outcomes, and Influence of Historical Redlining.

BACKGROUND: The discriminatory and racist policy of historical redlining in the United States (U.S.) during the 1930s played a role in perpetuating contemporary environmental health disparities. OBJECTIVE: Our objectives were to determine associations between home and school pollutant exposure (fine particulate matter (PM2.5), nitrogen dioxide (NO2)) and respiratory outcomes (Composite Asthma Severity Index (CASI), lung function) among school-aged children with asthma and examine whether associations differed between children who resided and/or attended school in historically redlined compared to non-redlined neighborhoods. METHODS: Children ages 6 to 17 with moderate-to-severe asthma (N=240) from 9 U.S. cities were included. Combined home and school exposure to PM2.5 and NO2 was calculated based on geospatially assessed monthly averaged outdoor pollutant concentrations. Repeated measures of CASI and lung function were collected. RESULTS: Overall, 37.5% of children resided and/or attended schools in historically redlined neighborhoods. Children in historically redlined neighborhoods had greater exposure to NO2 (median: 15.4 vs 12.1 ppb) and closer distance to a highway (median: 0.86 vs 1.23 km), compared to those in non-redlined neighborhoods (p<0.01). Overall, PM2.5 was not associated with asthma severity or lung function. However, among children in redlined neighborhoods, higher PM2.5 was associated with worse asthma severity (p<0.005). No association was observed between pollutants and lung function or asthma severity among children in non-redlined neighborhoods (p>0.005). CONCLUSIONS: Our findings highlight the significance of historical redlining and current environmental health disparities among school-aged children with asthma, specifically, the environmental injustice of PM2.5 exposure and its associations with respiratory health.

High TSLP responses in the human infant airways are associated with pre-activated airway epithelial IFN antiviral immunity.

Thymic stromal lymphopoietin (TSLP) is a primarily epithelial-derived cytokine that drives type 2 allergic immune responses. Early life viral respiratory infections elicit high TSLP production, which leads to the development of type 2 inflammation and airway hyperreactivity. The goal of this study was to examine in vivo and in vitro the human airway epithelial responses leading to high TSLP production during viral respiratory infections in early infancy. A total of 129 infants (<1-24 m, median age 10 m) with severe viral respiratory infections were enrolled for in vivo (n = 113), and in vitro studies (n = 16). Infants were classified as 'high TSLP' or 'low TSLP' for values above or below the 50th percentile. High versus low TSLP groups were compared in terms of type I-III IFN responses and production of chemokines promoting antiviral (CXCL10), neutrophilic (CXCL1, CXCL5, CXCL8), and type 2 responses (CCL11, CCL17, CCL22). Human infant airway epithelial cell (AEC) cultures were used to define the transcriptomic (RNAseq) profile leading to high versus low TSLP responses in vitro in the absence (baseline) or presence (stimulated) of a viral mimic (poly I:C). Infants in the high TSLP group had greater in vivo type III IFN airway production (median type III IFN in high TSLP 183.2 pg/mL vs. 63.4 pg/mL in low TSLP group, p = 0.007) and increased in vitro type I-III IFN AEC responses after stimulation with a viral mimic (poly I:C). At baseline, our RNAseq data showed that infants in the high TSLP group had significant upregulation of IFN signature genes (e.g., IFIT2, IFI6, MX1) and pro-inflammatory chemokine genes before stimulation. Infants in the high TSLP group also showed a baseline AEC pro-inflammatory state characterized by increased production of all the chemokines assayed (e.g., CXCL10, CXCL8). High TSLP responses in the human infant airways are associated with pre-activated airway epithelial IFN antiviral immunity and increased baseline AEC production of pro-inflammatory chemokines. These findings present a new paradigm underlying the production of TSLP in the human infant airway epithelium following early life viral exposure and shed light on the long-term impact of viral respiratory illnesses during early infancy and beyond childhood.

StethAid: A Digital Auscultation Platform for Pediatrics.

(1) Background: Mastery of auscultation can be challenging for many healthcare providers. Artificial intelligence (AI)-powered digital support is emerging as an aid to assist with the interpretation of auscultated sounds. A few AI-augmented digital stethoscopes exist but none are dedicated to pediatrics. Our goal was to develop a digital auscultation platform for pediatric medicine. (2) Methods: We developed StethAid-a digital platform for artificial intelligence-assisted auscultation and telehealth in pediatrics-that consists of a wireless digital stethoscope, mobile applications, customized patient-provider portals, and deep learning algorithms. To validate the StethAid platform, we characterized our stethoscope and used the platform in two clinical applications: (1) Still's murmur identification and (2) wheeze detection. The platform has been deployed in four children's medical centers to build the first and largest pediatric cardiopulmonary datasets, to our knowledge. We have trained and tested deep-learning models using these datasets. (3) Results: The frequency response of the StethAid stethoscope was comparable to those of the commercially available Eko Core, Thinklabs One, and Littman 3200 stethoscopes. The labels provided by our expert physician offline were in concordance with the labels of providers at the bedside using their acoustic stethoscopes for 79.3% of lungs cases and 98.3% of heart cases. Our deep learning algorithms achieved high sensitivity and specificity for both Still's murmur identification (sensitivity of 91.9% and specificity of 92.6%) and wheeze detection (sensitivity of 83.7% and specificity of 84.4%). (4) Conclusions: Our team has created a technically and clinically validated pediatric digital AI-enabled auscultation platform. Use of our platform could improve efficacy and efficiency of clinical care for pediatric patients, reduce parental anxiety, and result in cost savings.

Effect of the coronavirus disease 2019 pandemic on morbidity among children hospitalized for an asthma exacerbation.

BACKGROUND: Pediatric asthma exacerbations account for substantial morbidity, including emergency department (ED) visits and hospitalizations. Although the coronavirus disease 2019 (COVID-19) pandemic was associated with a decrease in pediatric asthma ED visits and hospitalizations, there is limited information on the clinical characteristics of children hospitalized with an asthma exacerbation during the pandemic. OBJECTIVE: To investigate the clinical characteristics of children hospitalized with an asthma exacerbation during the pandemic as compared with those hospitalized during the same months in the year prior. METHODS: A retrospective case-control study was conducted at the Children's National Hospital, Washington, DC, comparing demographic and clinical characteristics of all children, 2 to 18 years old, hospitalized for an asthma exacerbation between April to September 2020 (cases) and April to September 2019 (controls). RESULTS: We identified 50 cases and 243 controls. Cases were significantly older than controls (9.8 ± 4.3 years vs 6.7 ± 3.8 years; P < .001), had significantly less eczema (16% vs 32.1%; P = .02) and food allergies (6% vs 18.5%; P = .03), and were more noncompliant with controller medications (46% vs 24.7%; P = .002) than controls. Magnesium sulfate was more frequently administered in the ED to the cases than to the controls (84% vs 63%; P = .004). Its use was associated with older age, African American race, and Hispanic ethnicity, but was independent of comorbid conditions. CONCLUSION: Patients hospitalized for asthma during the COVID-19 pandemic were older and have less atopy than those hospitalized prepandemic. A larger proportion received magnesium sulfate in the ED, suggesting patients had with more severe asthma presentation during the pandemic.

Spirometric Changes After Initiation of Hydroxyurea in Children With Sickle Cell Anemia.

Individuals with sickle cell disease (SCD) develop a decline in lung function over time. Hydroxyurea (HU) is the most common disease-modifying therapy used in SCD. We hypothesized that children with SCD treated with HU will have a slower decline in pulmonary function. We performed a retrospective chart review of children with HbSS and HbS-beta zero thalassemia referred to pulmonology for respiratory symptoms. We compared the spirometry results at 2 time points between children on HU (HU group) and not on HU (control group). For the HU group, these endpoints were evaluated before and after being on HU. The mean time interval between 2 spirometry studies was not significantly different between the groups (2.6±1.5 y for HU group vs. 3.0±1.8 y for the control group; P =0.33). The mean age of patients in the HU group was 9.8±3.8 years (55% male) and 10.7±4.9 years (50% male) in the control group. The spirometry data was compared within and between the groups using t test. There was a significant increase in forced vital capacity in HU group during follow-up, while children in the control group showed a decline (7.2±17.1 vs. -3.4±18.2; P <0.01). Our study suggests that HU therapy may help preserve lung function over time in children with SCD.

Paediatric obesity-related asthma: Disease burden and effects on pulmonary physiology.

The prevalence of asthma and obesity in children has been steadily increasing globally over the past several decades, with increased concern in low and middle income countries. In this review, we summarize the current literature on these two parallel epidemics and explore the relationship between paediatric obesity and asthma in the paediatric population. Finally, we focus on the current literature as it relates to underlying physiologic alterations and changes in pulmonary function for children with obesity and asthma.

Pediatric sleep questionnaire predicts more severe sleep apnea in children with uncontrolled asthma.

OBJECTIVE: While up to 35% of children with asthma have evidence of sleep disordered breathing (SDB), it is unclear if nocturnal symptoms stem from asthma itself or SDB. The Pediatric Sleep Questionnaire (PSQ) is a validated tool for identifying SDB in childhood asthma. We hypothesize children with asthma and abnormal PSQ demonstrate decreased asthma control and are at higher risk of obstructive sleep apnea (OSA). METHODS: We performed a retrospective, chart review of children and young adults referred to our tertiary children's hospital severe asthma clinic. Data collection included age, gender, BMI percentile, spirometry, PSQ, asthma control questionnaires, asthma severity, control, and impairment. These data were evaluated in the context of polysomnography, when available. RESULTS: 205 inner-city children were included; 37.2% female, median age 6.4 y, and mean BMI of 71.3%ile. Rhinitis (p = 0.028), eczema (p = 0.002), and reflux (p = 0.046) were associated with abnormal PSQ; however, overweight/obese status, spirometry, asthma severity, and serologic markers were not. After correcting for comorbidities, abnormal PSQ score was associated with poor asthma control based on validated measures (p < 0.001). In patients with polysomnography, we confirmed abnormal PSQ was associated with increased OSA severity (apnea-hypopnea index 9.1/hr vs. 3.6/hr; p = 0.027). CONCLUSIONS: In pediatric asthma, positive PSQ was associated with significantly decreased asthma control. Additionally, children with normal PSQ demonstrated mild OSA, while children with abnormal PSQ had increased severity of OSA. This demonstrates that PSQ can be used to screen children for more severe sleep apnea.

Innate IFN-lambda responses to dsRNA in the human infant airway epithelium and clinical regulatory factors during viral respiratory infections in early life.

INTRODUCTION: IFN lambda (type III-IFN-λ1) is a molecule primarily produced by epithelial cells that provides an important first-line defence against viral respiratory infections and has been linked to the pathogenesis of viral-induced wheezing in early life. The goal of this study was to better understand the regulation of innate IFN-lambda responses in vitro in primary human infant airway epithelial cells (AECs) and in vivo using nasal aspirates during viral respiratory infections. METHODS: IFN-lambda protein levels were quantified: (a) in human infant AECs exposed to (poly(I:C) dsRNA) under different experimental conditions (n = 8 donors); and (b) in nasal aspirates of young children (≤3 years) hospitalized with viral respiratory infection (n = 138) and in uninfected controls (n = 74). In vivo IFN-lambda airway levels during viral infections were correlated with individual characteristics and respiratory disease parameters. RESULTS: Our in vitro experiments showed that the poly(I:C)-induced innate production of IFN lambda in human infant AECs is regulated by (a) p38-MAPK/NF-kB dependent mechanism; and (b) exposure to pro-inflammatory signals such as IL1ß. Our in vivo studies demonstrated that (a) infants (<18 months) had higher virus-induced IFN-lambda airway secretion; (b) subjects with RSV infection showed the highest IFN-lambda airway levels; and (c) individuals with the highest virus-induced IFN-lambda levels (>90th percentile) had higher viral loads and were more likely to have respiratory sick visits within 12 months of discharge (OR = 5.8). CONCLUSION: IFN-lambda responses to dsRNA in the human infant airway epithelium are regulated by p38-MAPK and NF-kB signalling. High in vivo IFN-lambda production is influenced by virus type and associated with recurrent respiratory sick visits in young children.

A Cloud-connected NO2 and Ozone Sensor System for Personalized Pediatric Asthma Research and Management.

This paper presents a cloud-connected indoor air quality sensor system that can be deployed to patients' homes to study personal microenvironmental exposure for asthma research and management. The system consists of multiple compact sensor units that can measure residential NO2, ozone, humidity, and temperature at one-minute resolution and a cloud-based informatic system that acquires, stores, and visualizes the microenvironmental data in real-time. The sensor hardware can measure NO2 as low as 10 ppb and ozone at 15 ppb. The cloud informatic system is implemented using open-source software on Amazon Web Service for easy deployment and scalability. This system was successfully deployed to pediatric asthma patients' homes in a pilot study. In this study, we discovered that some families had short-term NO2 exposure higher than EPA's one-hour exposure limit (100 ppb), and NO2 micro-pollution episodes often arise from natural gas appliance usage such as gas stove burning during cooking. By combining the personalized air pollutant exposure measurements with the physiological responses from monitoring devices, patient diaries, or medical records, this system can potentially enable novel asthma research and personalized asthma management.

A Heterotopic Xenograft Model of Human Airways for Investigating Fibrosis in Asthma.

Limited in vivo models exist to investigate the lung airway epithelial role in repair, regeneration, and pathology of chronic lung diseases. Herein, we introduce a novel animal model in asthma-a xenograft system integrating a differentiating human asthmatic airway epithelium with an actively remodeling rodent mesenchyme in an immunocompromised murine host. Human asthmatic and nonasthmatic airway epithelial cells were seeded into decellularized rat tracheas. Tracheas were ligated to a sterile cassette and implanted subcutaneously in the flanks of nude mice. Grafts were harvested at 2, 4, or 6 weeks for tissue histology, fibrillar collagen, and transforming growth factor-ß activation analysis. We compared immunostaining in these xenografts to human lungs. Grafted epithelial cells generated a differentiated epithelium containing basal, ciliated, and mucus-expressing cells. By 4 weeks postengraftment, asthmatic epithelia showed decreased numbers of ciliated cells and decreased E-cadherin expression compared with nonasthmatic grafts, similar to human lungs. Grafts seeded with asthmatic epithelial cells had three times more fibrillar collagen and induction of transforming growth factor-ß isoforms at 6 weeks postengraftment compared with nonasthmatic grafts. Asthmatic epithelium alone is sufficient to drive aberrant mesenchymal remodeling with fibrillar collagen deposition in asthmatic xenografts. Moreover, this xenograft system represents an advance over current asthma models in that it permits direct assessment of the epithelial-mesenchymal trophic unit.

Quantitative proteomics reveals an altered cystic fibrosis in vitro bronchial epithelial secretome.

Alterations in epithelial secretions and mucociliary clearance contribute to chronic bacterial infection in cystic fibrosis (CF) lung disease, but whether CF lungs are unchanged in the absence of infection remains controversial. A proteomic comparison of airway secretions from subjects with CF and control subjects shows alterations in key biological processes, including immune response and proteolytic activity, but it is unclear if these are due to mutant CF transmembrane conductance regulator (CFTR) and/or chronic infection. We hypothesized that the CF lung apical secretome is altered under constitutive conditions in the absence of inflammatory cells and pathogens. To test this, we performed quantitative proteomics of in vitro apical secretions from air-liquid interface cultures of three life-extended CF (ΔF508/ΔF508) and three non-CF human bronchial epithelial cells after labeling of CF cells by stable isotope labeling with amino acids in cell culture. Mass spectrometry analysis identified and quantitated 666 proteins across samples, of which 70 exhibited differential enrichment or depletion in CF secretions (±1.5-fold change; P < 0.05). The key molecular functions were innate immunity (24%), cytoskeleton/extracellular matrix organization (24%), and protease/antiprotease activity (17%). Oxidative proteins and classical complement pathway proteins that are altered in CF secretions in vivo were not altered in vitro. Specific differentially increased proteins-MUC5AC and MUC5B mucins, fibronectin, and matrix metalloproteinase-9-were validated by antibody-based assays. Overall, the in vitro CF secretome data are indicative of a constitutive airway epithelium with altered innate immunity, suggesting that downstream consequences of mutant CFTR set the stage for chronic inflammation and infection in CF airways.

Adipocyte-derived exosomal miRNAs: a novel mechanism for obesity-related disease.

BACKGROUND: Obesity is frequently complicated by comorbid conditions, yet how excess adipose contributes is poorly understood. Although adipocytes in obese individuals induce systemic inflammation via secreted cytokines, another potential mediator has recently been identified (i.e., adipocyte-derived exosomes). We hypothesized that adipocyte-derived exosomes contain mediators capable of activating end-organ inflammatory and fibrotic signaling pathways. METHODS: We developed techniques to quantify and characterize exosomes shed by adipocytes from seven obese (age: 12-17.5 y, BMI: 33-50 kg/m(2)) and five lean (age: 11-19 y, BMI: 22-25 kg/m(2)) subjects. RESULTS: Abundant exosomal miRNAs, but no mRNAs, were detected. Comparison of obese vs. lean visceral adipose donors detected 55 differentially expressed miRNAs (P < 0.05; fold change ≥|1.2|). qRT-PCR confirmed downregulation of miR-148b (ratio = 0.2 (95% confidence interval = 0.1, 0.6)) and miR-4269 (0.3 (0.1, 0.8)), and upregulation of miR-23b (6.2 (2.2, 17.8)) and miR-4429 (3.8 (1.1-13.4)). Pathways analysis identified TGF-ß signaling and Wnt/ß-catenin signaling among the top canonical pathways expected to be altered with visceral adiposity based on projected mRNA targets for the 55 differentially expressed miRNAs. A select mRNA target was validated in vitro. CONCLUSION: These data show that visceral adipocytes shed exosomal-mediators predicted to regulate key end-organ inflammatory and fibrotic signaling pathways.

Directional secretomes reflect polarity-specific functions in an in vitro model of human bronchial epithelium.

The polarity of the conducting airway epithelium is responsible for its directional secretion. This is an essential characteristic of lung integrity and function that dictates interactions between the external environment (apical) and subepithelial structures (basolateral). Defining the directional secretomes in the in vitro human bronchial epithelial (HBE) differentiated model could bring valuable insights into lung biology and pulmonary diseases. Normal primary HBE cells (n = 3) were differentiated into respiratory tract epithelium. Apical and basolateral secretions (24 h) were processed for proteome profiling and pathway analysis. A total of 243 proteins were identified in secretions from all HBE cultures combined. Of these, 51% were classified as secreted proteins, including true secreted proteins (36%) and exosomal proteins (15%). Close examination revealed consistent secretion of 69 apical proteins and 13 basolateral proteins and differential secretion of 25 proteins across all donors. Expression of Annexin A4 in apical secretions and Desmoglein-2 in basolateral secretions was validated using Western blot or ELISA in triplicate independent experiments. To the best of our knowledge, this is the first study defining apical and basolateral secretomes in the in vitro differentiated HBE model. The data demonstrate that epithelial polarity directs protein secretion with different patterns of biological processes to the apical and basolateral surfaces that are consistent with normal bronchial epithelium homeostatic functions. Applying this in vitro directional secretome model to lung diseases may elucidate their molecular pathophysiology and help define potential therapeutic targets.

The human secretome atlas initiative: implications in health and disease conditions.

Proteomic analysis of human body fluids is highly challenging, therefore many researchers are redirecting efforts toward secretome profiling. The goal is to define potential biomarkers and therapeutic targets in the secretome that can be traced back in accessible human body fluids. However, currently there is a lack of secretome profiles of normal human primary cells making it difficult to assess the biological meaning of current findings. In this study we sought to establish secretome profiles of human primary cells obtained from healthy donors with the goal of building a human secretome atlas. Such an atlas can be used as a reference for discovery of potential disease associated biomarkers and eventually novel therapeutic targets. As a preliminary study, secretome profiles were established for six different types of human primary cell cultures and checked for overlaps with the three major human body fluids including plasma, cerebrospinal fluid and urine. About 67% of the 1054 identified proteins in the secretome of these primary cells occurred in at least one body fluid. Furthermore, comparison of the secretome profiles of two human glioblastoma cell lines to this new human secretome atlas enabled unambiguous identification of potential brain tumor biomarkers. These biomarkers can be easily monitored in different body fluids using stable isotope labeled standard proteins. The long term goal of this study is to establish a comprehensive online human secretome atlas for future use as a reference for any disease related secretome study. This article is part of a Special Issue entitled: An Updated Secretome.

Asthma as a comorbidity in COVID-19 pediatric ICU admissions in a large metropolitan children's hospital.

RATIONALE: Children contribute to 5% of coronavirus disease of 2019 (COVID-19)-related hospitalizations in the United States. There is mounting evidence suggesting childhood asthma is a risk factor for severe disease. We hypothesized that asthma is associated with longer length of stay (LOS) and need for respiratory support among children admitted to pediatric intensive care unit (PICU) with COVID-19. METHODS: We reviewed 150 charts of children and young adults with a positive severe acute respiratory syndrome coronavirus 2polymerase chain reaction test admitted to the PICU at Children's National Hospital, Washington, DC between 2020 and 2021. We recorded demographics, anthropometrics, past medical history, clinical course, laboratory findings, imaging, medication usage, respiratory support, and outcomes. Functional Status Scale (FSS), which measures an Intensive Care Unitpatient's physical function, was used to characterize children with multiple comorbidities; FSS and obesity were included as covariates in multivariate analysis. Statistical analysis was performed using SPSS v25.0. RESULTS: Sixty-Eight patients ages 0-21 years met inclusion criteria. Median age was 14.9 years, 55.9% were female, median Body Mass Index percentile was 62, and 42.6% were African American. Compared with those without asthma, patients with asthma averaged longer LOS (20.7 vs. 10.2 days, p = 0.02), with longer PICU stay (15.9 vs. 7.6 days, p = 0.033) and prolonged maximum respiratory support (8.3 vs. 3.3 days, p = 0.016). Adjusted for obesity and poor physical function (FSS > 6), asthma remained a significant predictor of hospital LOS, PICU LOS, and days on maximum respiratory support. CONCLUSION: Asthma can cause severe disease with prolonged need for maximum respiratory support among children with COVID-19.

TSLP bronchoalveolar lavage levels at baseline are linked to clinical disease severity and reduced lung function in children with asthma.

Rationale: Thymic stromal lymphopoietin (TSLP) is increasingly recognized as a key molecule in asthma pathogenesis and as a promising therapeutic target in adults. In contrast, in asthmatic children the clinical relevance of TSLP secretion in the lower airways has been remarkably understudied. We tested the hypothesis that pulmonary TSLP levels in asthmatic children correlate with clinical severity, airway inflammation and lower airway obstruction. Methods: Bronchoalveolar lavage (BAL) samples and relevant clinical data were collected from asthmatic children undergoing clinically indicated bronchoscopy at Children's National Hospital in Washington D.C. Protein levels of TSLP, IL-5, IL-1ß, and IL-33 were quantified in BAL at baseline and correlated with individual severity and clinical features including spirometry, serum IgE and eosinophils, BAL neutrophil and eosinophil counts. Results: We enrolled a total of 35 asthmatic children (median age: 9 years). Pediatric subjects with severe asthma had greater TSLP BAL levels at baseline relative to mild or moderate asthmatic subjects (p = 0.016). Asthmatic children with the highest TSLP levels (>75th percentile) had higher IL-5 and IL-1ß BAL levels and greater lower airway obstruction (lower FEV1/FVC ratios). Conclusion: Our study demonstrates for the first time that higher pulmonary TSLP levels obtained at baseline are linked to asthma disease severity in a subset of children. These data indicate that TSLP may play a key role in the pathogenesis of pediatric asthma and thus provide initial support to investigate the potential use of anti-TSLP biologics to treat severe uncontrolled asthmatic children.

Personal NO2 sensor demonstrates feasibility of in-home exposure measurements for pediatric asthma research and management.

BACKGROUND: One of the most common pollutants in residences due to gas appliances, NO2 has been shown to increase the risk of asthma attacks after small increases in short term exposure. However, standard environmental sampling methods taken at the regional level overlook chronic intermittent exposure due to lack of temporal and spatial granularity. Further, the EPA and WHO do not currently provide exposure recommendations to at-risk populations. AIMS: A pilot study with pediatric asthma patients was conducted to investigate potential deployment challenges as well as benefits of home-based NO2 sensors and, when combined with a subject's hospital records and self-reported symptoms, the richness of data available for larger-scale epidemiological studies. METHODS: We developed a compact personal NO2 sensor with one minute temporal resolution and sensitivity down to 15 ppb to monitor exposure levels in the home. Patient hospital records were collected along with self-reported symptom diaries, and two example hypotheses were created to further demonstrate how data of this detail may enable study of the impact of NO2 in this sensitive population. RESULTS: 17 patients (55%) had at least 1 h each day with average NO2 exposure >21 ppb. Frequency of acute NO2 exposure >21 ppb was higher in the group with gas stoves (U = 27, p ≤ 0.001), and showed a positive correlation (rs = 0.662, p = 0.037, 95% CI 0.36-0.84) with hospital admissions. SIGNIFICANCE: Similar studies are needed to evaluate the true impact of NO2 in the home environment on at-risk populations, and to provide further data to regulatory bodies when developing updated recommendations.

Asthmatic airway epithelium is intrinsically inflammatory and mitotically dyssynchronous.

Asthma is an inflammatory condition for which anti-inflammatory glucocorticoids are the standard of care. However, similar efficacy has not been shown for agents targeting inflammatory cells and pathways. This suggests a noninflammatory cell contributor (e.g., epithelium) to asthmatic inflammation. Herein, we sought to define the intrinsic and glucocorticoid-affected properties of asthmatic airway epithelium compared with normal epithelium. Human primary differentiated normal and asthmatic airway epithelia were cultured in glucocorticoid-free medium beginning at -48 hours. They were pulsed with dexamethasone (20 nM) or vehicle for 2 hours at -26, -2, +22, and +46 hours. Cultures were mechanically scrape-wounded at 0 hours and exposed continuously to bromodeoxyuridine (BrdU). Cytokine secretions were analyzed using cytometric bead assays. Wound regeneration/mitosis was analyzed by microscopy and flow cytometry. Quiescent normal (n = 3) and asthmatic (n = 6) epithelia showed similar minimal inflammatory cytokine secretion and mitotic indices. After wounding, asthmatic epithelia secreted more basolateral TGF-ß1, IL-10, IL-13, and IL-1ß (P < 0.05) and regenerated less efficiently than normal epithelia (+48 h wound area reduction = [mean ± SEM] 50.2 ± 7.5% versus 78.6 ± 7.7%; P = 0.02). Asthmatic epithelia showed 40% fewer BrdU(+) cells at +48 hours (0.32 ± 0.05% versus 0.56 ± 0.07% of total cells; P = 0.03), and those cells were more dyssynchronously distributed along the cell cycle (52 ± 10, 25 ± 4, 23 ± 7% for G1/G0, S, and G2/M, respectively) than normal epithelia (71 ± 1, 12 ± 2, and 17 ± 2% for G1/G0, S, and G2/M, respectively). Dexamethasone pulses improved asthmatic epithelial inflammation and regeneration/mitosis. In summary, we show that inflammatory/fibrogenic cytokine secretions are correlated with dyssynchronous mitosis upon injury. Intermittent glucocorticoids simultaneously decreased epithelial cytokine secretions and resynchronized mitosis. These data, generated in an airway model lacking inflammatory cells, support the concept that epithelium contributes to asthmatic inflammation.