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.

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.

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.

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.

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.

Positive bronchoalveolar lavage pepsin assay associated with viral and fungal respiratory infections in children with chronic cough.

OBJECTIVE: To assess the association between commonly obtained endoscopic and serologic data and bronchoalveolar lavage pepsin assay (BAL) results in children with chronic cough. STUDY DESIGN: We performed a retrospective chart review of 72 children with a BAL pepsin obtained through our Aerodigestive Center over an 18-month period. BAL outcomes include evidence of viral, bacterial, or fungal infection, presence of lipid-laden macrophages, and cytology (eosinophils, neutrophils, and lymphocytes). Gastrointestinal outcomes include esophagogastroduodenoscopy (EGD) and pH impedance probe findings. Other characteristics include serum eosinophils, neutrophils, and lymphocytes; spirometry; FeNO; and IgE. RESULTS: Seventy-two patients underwent BAL pepsin testing. Median age was 4.9 years, 30.6% had severe persistent asthma, and 59.2% were on reflux medication. There was an association between positive BAL pepsin assay and positive viral panel (p = .002) or fungal culture (p = .027). No significant association found between positive BAL bacterial culture; BAL cytology; the presence of BAL lipid-laden macrophages; IgE; spirometry; FeNO; CBC neutrophil, eosinophil, or lymphocytes; pH impedance testing parameters; or EGD pathology. CONCLUSIONS: BAL pepsin is associated with a positive BAL viral PCR or fungal culture. Lack of correlation between pepsin-positivity and pH-impedance parameters or EGD pathology suggests microaspiration may be due to an acute event (such as a respiratory infection) rather than chronic gastroesophageal reflux disease. This may be especially true in the presence of a positive viral panel or fungal culture when a BAL pepsin is obtained.

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.

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.

High BAL sRAGE is Associated with Low Serum Eosinophils and IgE in Children with Asthma.

Asthma remains the most common chronic lung disease in childhood in the United States. The receptor for advanced glycation end products (RAGE) has been recognized as both a marker of and participant in pulmonary pathophysiology. While membrane-bound RAGE (mRAGE) perpetuates the type 2 immune response, the soluble form (sRAGE) may act as a decoy receptor for pro-inflammatory ligands. Bronchoalveolar samples from 45 pediatric patients with asthma were obtained. Patients were divided into high and low BAL sRAGE groups using median sRAGE. Descriptive statistical analysis and non-parametric testing were applied. Children in the "high" sRAGE group had a lower median serum eosinophil (0.27 [SE ± 0.04] vs. 0.57 [± 0.06] K/mcl, adjusted p = 0.003) and lower serum IgE level (194.4 [± 60.7] vs. 676.2 ± 140.5) IU/mL, adjusted p = 0.004) as compared to the "low" sRAGE group. When controlling for age and body mass index percentile, absolute eosinophil count (p = 0.03) and serum IgE (p = 0.043) remained significantly lower in the "high" sRAGE group. Children with asthma and high levels of BAL sRAGE have lower serum eosinophil and IgE levels. These findings are consistent with the hypothesis that sRAGE may act as a decoy receptor by binding ligands that normally interact with mRAGE.

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.

Pediatric Quality-of-Life Scores Following a Multidisciplinary Aerodigestive Team Approach to Manage Chronic Cough.

OBJECTIVES: Chronic recalcitrant cough is present in 2/3 of pediatric patients evaluated in our tertiary-care multidisciplinary aerodigestive clinic (ADC). This study aimed to determine the impact of chronic cough and efficacy of ADC treatment using the validated Pediatric-Cough Quality-of-Life-27 tool (PC-QOL-27). METHODS: The PC-QOL-27 survey was administered to ADC patients with chronic cough at initial clinic visit and 6 to 12 weeks after cough management. Pre and post survey scores, demographic data, treatment and evaluation season were collected over 16 months. RESULTS: Twenty parents completed pre and post PC-QOL-27 surveys (mean 12.1 weeks later). Patient median age was 6.04 years (IQR: 2.2-10.44 years). A total of 65% were males and 65% were African American. Management was tailored based on clinical assessment and diagnostic studies, including direct laryngoscopy/bronchoscopy (4), pulmonary function tests (PFT's 9), esophagogastroduodenoscopy (9), and flexible bronchoscopy/lavage (9).Following ADC management, changes in physical, social and psychological domain scores of the PC-QOL-27 each met the threshold for minimal clinical important difference (MCID) indicating a clinically meaningful improvement. Improvements were most notable in the physical domain where post survey scores significantly improved from pre-survey scores (P = .009) regardless of age, gender, ethnicity, history of endoscopy and season. CONCLUSIONS: The physical impact of chronic cough in pediatric patients who failed prior management by a single specialist was lessened by an ADC team approach to management.

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.

Aerodigestive Approach to Chronic Cough in Children.

PURPOSE OF REVIEW: Chronic cough is the most common presenting complaint in a pediatric aerodigestive clinic. The etiology of chronic cough is varied and often includes more than one organ system. This review aims to summarize the current literature for a multidisciplinary approach when evaluating a child with chronic cough. RECENT FINDINGS: There is very little medical literature focused on a multidisciplinary approach to chronic cough. In the limited data available, multidisciplinary clinics have been shown to be more cost-efficient for the families of children with complex medical problems, and also increase the likelihood of successfully obtaining a diagnosis. SUMMARY: There is no consensus in the literature on how to work-up a child with chronic cough presenting to an aerodigestive clinic. Current studies from these clinics have shown improved outcomes related to cost-effectiveness and identifying definitive diagnoses. Future studies evaluating clinical outcomes are necessary to help delineate the utility of testing routinely performed, and to demonstrate the impact of interventions from each specialty on quality of life and specific functional outcome measures.

Sino-Nasal 5 Questionnaire is Associated with Poor Asthma Control in Children with Asthma.

Up to 80% of asthmatic children may experience upper airway symptoms which are often perceived as coming from the lower airways. Currently, there are no validated questionnaires to assess upper airway contribution to pediatric asthma symptoms. The Sino-Nasal 5 (SN-5) questionnaire was previously validated for identifying radiographic confirmed sinus disease in children. In this study, we hypothesize that significant SN-5 scores (≥3.5) are associated with abnormal National Asthma Education and Prevention Program (NAEPP) based asthma impairment and control in asthmatic children. Retrospective data collected on children with asthma referred for pulmonary evaluation included age, gender, ethnicity, NAEPP asthma severity, asthma control (Test for Respiratory and Asthma Control in Kids (TRACK) < 5 years, Asthma Control Test (ACT) 5 years) and pulmonary function testing. Associations between SN-5 scores and asthma impairment and control were identified. Seventy-six children were evaluated; 38% were female with a mean age of 6.9 years. Significant SN-5 scores were associated with decreased control of daytime symptoms (odds ratio (OR): 0.16 (95% confidence interval (CI): 0.06-0.44)), night time awakenings (0.09 (0.03-0.29)), activity interference (0.2 (0.06-0.68)), NAEPP defined asthma control (0.32 (0.12-0.85)) and poor asthma control based on TRACK (p < 0.001) and ACT (p < 0.001). This suggests upper airways may play a larger role in perceived lower airway symptoms, and SN-5 may be beneficial in assessing the contribution of upper airway conditions on asthma control.

Is a Multidisciplinary Aerodigestive Clinic More Effective at Treating Recalcitrant Aerodigestive Complaints Than a Single Specialist?

OBJECTIVE: To determine the utility of a pediatric multidisciplinary aerodigestive clinic (ADC) in treating recalcitrant aerodigestive conditions. METHODS: Longitudinal observational study of presenting complaints, evaluation, management, and outcome of patients seen during 12 monthly ADCs beginning August 2013. RESULTS: Fifty-five patients were seen by the ADC team (otolaryngology/gastroenterology/pulmonology/speech pathology/nurse practitioner) and followed for a mean 17.6 months (range, 12-26 months). Mean age was 4.3 years (range, 0.5-19 years). All were seen by at least 1 specialist before ADC referral but without significant improvement. Chronic cough was the most common primary symptom (44%). Clinic evaluation included flexible nasopharyngolaryngoscopy (FFL, 53%) and pulmonary function testing (36%.) FFL influenced management in 79%. An operative procedure usually combined endoscopy was warranted in 58%. Endoscopy provided high diagnostic yield, detecting laryngeal cleft (8), adenoid hypertrophy (8), vocal cord dysfunction (4), pulmonary infection (4), reflux disease (3), laryngomalacia (3), tracheomalacia (2), cilia abnormality (2), celiac disease (1), Helicobacter pylori (1), duodenal web (1), and eosinophilic esophagitis (1). Outcome was available for 48 of 55 patients, with 73% reporting resolved to markedly improved symptoms and 27% minimal to no improvement. CONCLUSIONS: The ADC team approach resulted in resolved to markedly improved symptoms in 73% of patients whose symptoms persisted despite seeing a single specialist prior to referral.

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.