Small Airways Research Articles

Analysis of clinical characteristics and risk factors of chest tightness variant asthma in children

Objective: To analyze the clinical features and risk factors of chest tightness variant asthma (CTVA) in children, so as to provide basis for the prevention and management of the disease. Methods: A cross-sectional study was conducted to analyze 178 children aged 6-17 years old who were admitted to the Department of Allergy, Capital Institute of Pediatrics Affiliated Children's Hospital from January 2021 to January 2023 due to chest tightness. The age was 8.83(7.50, 11.58) years old, with 89 males (50%) and 89 females (50%). According to the diagnosis of CTVA, 130 cases were divided into CTVA group and 48 non-CTVA cases were divided into control group. Demographic data, personal history, family history, clinical features, auxiliary examination results and other data were collected. The clinical characteristics, allergens, FeNO level and pulmonary function parameters of the two groups were analyzed. Logistic regression analysis was used to explore the risk factors of the disease. Results: The proportion of school-age children (6-11 years old) in CTVA group was higher than that of adolescent children (≥12 years old) [(113/130,86.9%) vs (26/48,54.2%),Z=21.985,P<0.01]. The proportion of CTVA combined with eczema [(74/130,56.9%) vs (19/48,39.6%), χ2=4.225,P<0.05] and rhinitis symptoms [(98/130,75.4%) vs (27/48,56.2%), χ2=6.138,P<0.05] was higher. The positive rates of mold sensitization [(52/130,40.0%) vs (11/48,22.9%), χ2=4.474,P<0.05] and multiple sensitization [(71/130,54.6%) vs (18/48,37.5%), χ2=4.108,P<0.05] in inhaled allergens were significantly higher than those of control group. The proportion of elevated FeNO (>20 ppb) in CTVA children was 20.8% (27/130), which was significantly higher than that in control group 4.2%(2/48)(χ2=7.086,P<0.01). There were no statistical differences in spirometry parameters FEV1 and FVC between CTVA group and control group (P both>0.05). FEV1/FVC, PEF, FEF25, FEF50, FEF75 and MMEF were significantly lower than those in control group (P all<0.05). Logistic regression analysis showed that rhinitis symptoms (OR=2.351, 95%CI 1.105-5.002, P=0.026), multiple sensitizations (OR=2.184, 95%CI 1.046-4.557, P=0.038), tIgE>60 kU/L(OR=3.080, 95%CI 1.239-7.654, P=0.015), FeNO>20 ppb (OR=6.734, 95%CI 1.473-30.796, P=0.014) and small airway dysfunction (OR=3.164, 95%CI 1.089-9.194, P=0.034) were risk factors for chest tightness variant asthma. FeNO combined with FEF50 has the largest area under the curve (Z=2.744, P<0.01) in diagnosing CTVA. Conclusion: CTVA is more common in school-age children than in adolescent children. Rhinitis symptoms, multiple sensitization, tIgE>60 kU/L, FeNO>20 ppb and small airway dysfunction are risk factors for chest tightness variant asthma. FeNO combined with small airway indexes can improve the diagnostic value of CTVA.

Pulmonary Fibrosis Ferret Model Demonstrates Sustained Fibrosis, Restrictive Physiology, and Aberrant Repair.

The role of MUC5B mucin expression in IPF pathogenesis is unknown. Bleomycin-exposed rodent models do not exhibit sustained fibrosis or airway remodeling. Unlike mice, ferrets have human-like distribution of MUC5B expressing cell types and natively express the risk-conferring variant that induces high MUC5B expression in humans. We hypothesized that ferrets would consequently exhibit aberrant repair to propagate fibrosis similar to human IPF. Bleomycin (5U/kg) or saline-control was micro-sprayed intratracheally then wild-type ferrets were evaluated through 22 wks. Clinical phenotype was assessed with lung function. Fibrosis was assessed with µCT imaging and comparative histology with Ashcroft scoring. Airway remodeling was assessed with histology and quantitative immunofluorescence. Bleomycin ferrets exhibited sustained restrictive physiology including decreased inspiratory capacity, decreased compliance, and shifted Pressure-Volume loops through 22 wks. Volumetric µCT analysis revealed increased opacification of the lung bleomycin-ferrets. Histology showed extensive fibrotic injury that matured over time and MUC5B-positive cystic structures in the distal lung suggestive of honeycombing. Bleomycin ferrets had increased proportion of small airways that were double-positive for CCSP and alpha-tubulin compared to controls, indicating an aberrant 'proximalization' repair phenotype. Notably, this aberrant repair was associated with extent of fibrotic injury at the airway level. Bleomycin-exposed ferrets exhibit sustained fibrosis through 22 wks and have pathologic features of IPF not found in rodents. Ferrets exhibited proximalization of the distal airways and other pathologic features characteristic of human IPF. MUC5B expression through native cell types may play a key role in promoting airway remodeling and lung injury in IPF.

Epigenetic Regulation of Carbonic Anhydrase 9 Expression by Nitric Oxide in Human Small Airway Epithelial Cells.

DNA methylation is a crucial epigenetic modification that regulates gene expression and determines cell fate; however, the triggers that alter DNA methylation levels remain unclear. Recently, we showed that S-nitrosylation of DNA methyltransferase (DNMT) induces DNA hypomethylation and alters gene expression. Furthermore, we identified DBIC, a specific inhibitor of S-nitrosylation of DNMT3B, to suppress nitric oxide (NO)-induced gene alterations. However, it remains unclear how NO-induced DNA hypomethylation regulates gene expression and whether this mechanism is maintained in normal cells and triggers disease-related changes. To address these issues, we focused on carbonic anhydrase 9 (CA9), which is upregulated under nitrosative stress in cancer cells. We pharmacologically evaluated its regulatory mechanisms using human small airway epithelial cells (SAECs) and DBIC. We demonstrated that nitrosative stress promotes the recruitment of hypoxia-inducible factor 1 alpha to the CA9 promoter region and epigenetically induces CA9 expression in SAECs. Our results suggest that nitrosative stress is a key epigenetic regulator that may cause diseases by altering normal cell function.

Immunogenicity of biologics used in the treatment of asthma.

Asthma is a major global disease affecting adults and children, which can lead to hospitalization and death due to breathing difficulties. Although targeted monoclonal antibody therapies have revolutionized treatment of severe asthma, some patients still fail to respond. Here we critically evaluate the literature on biologic therapy failure in asthma patients with particular reference to anti-drug antibody production, and subsequent loss of response, as the potential primary cause of drug failure in asthma patients. Encouragingly, asthma in most cases responds to treatment, including the use of an increasing number of biologic drugs in moderate to severe disease. This includes monoclonal antibody inhibitors of immunoglobulin E and cytokines, including interleukin 4, 5, or 13 and thymic stromal lymphopoietin. These limit mast cell and eosinophil activity that cause the symptomatic small airways obstruction and exacerbations. Despite humanization of the antibodies, it is evident that benralizumab; dupilumab; mepolizumab; omalizumab; reslizumab and tezepelumab all induce anti-drug antibodies to some extent. These can contribute to adverse events including infusion reactions, serum sickness, anaphylaxis and potentially disease activity due to loss of therapeutic function. Monitoring anti-drug antibodies (ADA) may allow prediction of future treatment-failure in some individuals allowing treatment cessation and switching therefore potentially limiting disease breakthrough.

Iron Overload-induced Ferroptosis as a Target for Protection against Obliterative Bronchiolitis after Orthotopic Tracheal Transplantation in Mice.

The major complication of Obliterative Bronchiolitis (OB) is characterized by epithelial cell loss, fibrosis, and luminal occlusion of the terminal small airways, which limits the long-term survival of the recipient after lung transplantation. However, the underlying mechanisms are still not fully clarified. This research aims to investigate whether iron overload-induced ferroptosis is involved in OB development and provide a new target for OB prevention. Allograft orthotopic tracheal transplantation in mice was applied in our study. Ferrostatin-1 and deferoxamine were administrated to inhibit ferroptosis and get rid of ferric iron, while iron dextran was used to induce an iron overload condition in the recipient. The histological examination, luminal occlusion rate, collagen deposition, iron level, ferroptosis marker (GPX4, PTGS2), and mitochondrial morphological changes of the graft were evaluated in mice. Our research indicated that ferroptosis and iron overload contribute to OB development, while ferroptosis inhibition and iron chelator could reverse the changes. Iron overload exacerbated OB development after orthotopic tracheal transplantation via promoting ferroptosis. Overall, this research demonstrated that iron overload-induced ferroptosis is involved in OB, which may be a potential therapeutic target for OB after lung transplantation.

Impulse oscillometry in patients with persistent post-COVID-19 symptoms: A retrospective study.

Impaired lung function has been observed in patients following COVID-19 infection, with studies reporting persistent lung volume and diffusing capacity impairments. Some studies have demonstrated significantly higher small airway resistance in COVID-19 positive cases. This retrospective study aims to examine impulse oscillometry (IOS) data of patients with persistent symptoms after COVID-19 infection, focusing on the relationship between time and symptoms. The study analyzed data from adult patients with persistent symptoms who underwent IOS testing within and after 84 days from the diagnosis date. The results showed that patients within 84 days and those between 31 and 84 days had higher small airway resistance values, indicating peripheral airway disease. Patients with dyspnea exhibited higher IOS values compared to those with cough symptoms, suggesting more significant impairment in the peripheral airways. The study highlights the importance of using comprehensive diagnostic tools like IOS to assess respiratory impairments in post-COVID-19 patients, particularly in the small airways. Understanding the relationship between time and symptoms can provide valuable insights for the treatment of peripheral airway dysfunction in post-COVID-19 patients.

FOT Technique Applied for Monitoring of COVID-19 Pneumonia Reveals Small Airways Involvement.

The fact that some SARS-CoV-2 pneumonia patients benefit from changing body position, and some from continuous positive airways pressure (CPAP), indicates the functional character of hypoxia. We hypothesize that such effects could be explained by the closure of small airways. To prove the hypothesis, we evaluated the patency of small airways in 30 oxygen-dependent, spontaneously breathing patients with SARS-CoV-2 pneumonia during their hospital stay using the FOT method and then compared the results with data obtained three months later. During the acute period, total resistance (R5) and peripheral resistance (R5-20) rose above the upper limit of normal (ULN) in 28% and 50% of all patients, respectively. Reactance indices X5, AX and Fres exceeded ULN in 55%, 68% and 66% of cases. Significant correlations were observed between PaO2/FiO2, the time spent in the hospital and R5, X5, AX and Fres. After 3 months, 18 patients were re-examined. During the hospital stay, 11 of them had risen above the upper limit of normal (ULN), for both resistance (R5-20) and reactance (X5, AX) values. Three months later, ULN for R5-20 was exceeded in only four individuals, but ULN for X5 and AX was exceeded in five individuals. Lung function examination revealed a combined restrictive/obstructive ventilatory failure and reduced CO transfer factor. We interpret these changes as lung tissue remodeling due to the process of fibrosis. We conclude that during acute period of SARS-CoV-2 pneumonia, dilated pulmonary blood vessels and parenchymal oedema induce functional closure of small airways, which in turn induce atelectasis with pulmonary right-to-left shunting, followed by the resulting hypoxemia.

The adverse effects of vaping in young people

Vapes or e-cigarettes are battery operated devices that heat a liquid until it becomes a vapour, which is inhaled. Typically, e-liquids contain nicotine, different flavourings, and propylene glycol. Vaping devices are either disposable vapes or rechargeable. Vapes were initially developed as stop smoking aid but they have now become a recreational product popular among teenagers.Vaping has increased at an alarming rate among teenagers and young adults in Ireland. The European Schools Project for Alcohol and Other Drugs (ESPAD) survey 2019 showed that almost 4 in 10 Irish 16-year-olds had tried vaping and 15 % currently use them. More worrying is the dramatic rise in the use of disposable vapes in recent years. An Action on Smoking and Health (ASH) UK survey data revealed a 9-fold increase from 2021 to 2023 in their use (7.7 % to 69 %) among 11–17-year-old vapers.A combination of clever marketing by vaping companies, a strong social media presence, attractive flavours and easy accessibility has contributed to the increasing use of vapes by young people.Exposure of children and adolescents to nicotine in vaping solutions can lead to long-term negative impacts on brain development, as well as addiction. Many teenagers who vape experience poor concentration, anxiety, mood disorders and sleep disturbance. A paper from NEJM in 2022 reported a case series where chronic vaping resulted in small airway fibrosis of the airways. A systematic review conducted in 2021 concluded that teenager vapers were three to five times more likely to take up tobacco smoking when compared with non-vapers.Strong legislation is required to ban the sale of disposable vapes to teenagers along with controls on marketing online. Healthcare Professionals should ask and counsel their patients about vaping. Increased public awareness and education for Health care professionals on teenage vaping needs to be addressed.Vaping has become a global public health issue that must be addressed urgently.

Small Airways Obstruction and Mortality: Findings From the UK Biobank

BackgroundSmall airways obstruction (SAO) is common in general populations. It has been associated with respiratory symptoms, cardiometabolic diseases and progression to chronic obstructive pulmonary disease over time. Whether SAO predicts mortality is largely unknown. Research QuestionIs spirometry-defined SAO associated with increased mortality? MethodsWe analysed data from 252,877 adult participants, aged 40-69 at baseline, in the UK Biobank who had provided good quality spirometry measurements. We defined SAO as the ratio of the forced expiratory volume in three seconds to the forced expiratory volume in six seconds less than the lower limit of normal (FEV3/FEV6<LLN). We considered SAO to be isolated if present when the forced expiratory volume in one second to FEV6 ratio was normal (FEV1/FEV6≥LLN). We used a multivariable Cox regression model to assess the association of SAO, and isolated SAO, with all-cause and disease-specific mortality. We investigated sex differences in these associations and repeated the primary analysis excluding ever smokers. All models were adjusted for potential confounders such as sex, body mass index, smoking status, smoking pack-years, assessment centre, Townsend deprivation index and ethnicity. ResultsWe identified 59,744 participants with SAO of which 24,004 had isolated SAO. A total of 5,009 deaths were reported over a median of 12.8 years of follow-up. Participants with SAO had increased all-cause (HR=1.31, 95%CI 1.26-1.36), cardiovascular (HR=1.39, 95%CI 1.29-1.51), respiratory (HR=2.20, 95%CI 1.92-2.51), and neoplasm (HR=1.23, 95%CI 1.17-1.29) mortality risk. These associations were not modified by sex. However, in never smokers, only respiratory and cardiovascular mortality risk was associated with SAO. Isolated SAO was also associated with an increased mortality risk (HR=1.14, 95%CI 1.07-1.20). InterpretationIndividuals with SAO have an increased risk of all-cause and disease-specific mortality. Further studies are needed to determine whether SAO causes mortality or is a marker of underlying disease.

Bronchiolite obliterante post-infettiva (PIBO), chi è costei?

The paper presents the case of a 14-month-old child with a persistent respiratory distress with wheezing and diffuse crackles on chest auscultation. Symptoms appeared after a viral pneumonia caused by Adenovirus. The recent history, the clinical manifestations and the lung CT (Computed Tomography) scans, which showed a diffuse mosaic pattern, with air trapping, bronchiectasis and peribronchial inflammation, led to the diagnosis of Post-infectious Bronchiolitis Obliterans (PIBO). PIBO is a rare chronic paediatric pulmonary disease characterized by irreversible fibrotic narrowing of the small airways. It can present with a broad severity spectrum, and the evolution of this condition is not predictable in the single patient. Adenovirus is by far the most common cause of this lung pathology, and during the post Covid-19 pandemic an unprecedented rise in PIBO cases triggered by Adenovirus lower respiratory infections was observed. The treatment of PIBO is empirical, and a defined protocol does not exist yet. Therapeutic approaches range from nil to methylprednisolone pulse therapy, which would seem effective especially if performed early and if peribronchitis is found on imaging. Some studies evaluated the administration of intravenous immunoglobulins, while in more advanced cases showing fibrotic transformation of the parenchyma, the use of antifibrotic drugs (hydroxychloroquine, nintedanib) may be tried

Modelling Drug Delivery to the Small Airways: Optimization Using Response Surface Methodology

AimThe aim of this in silico study was to investigate the effect of particle size, flow rate, and tidal volume on drug targeting to small airways in patients with mild COPD.MethodDesign of Experiments (DoE) was used with an in silico whole lung particle deposition model for bolus administration to investigate whether controlling inhalation can improve drug delivery to the small conducting airways. The range of particle aerodynamic diameters studied was 0.4 – 10 µm for flow rates between 100 – 2000 mL/s (i.e., low to very high), and tidal volumes between 40 – 1500 mL.ResultsThe model accurately predicted the relationship between independent variables and lung deposition, as confirmed by comparison with published experimental data. It was found that large particles (~ 5 µm) require very low flow rate (~ 100 mL/s) and very small tidal volume (~ 110 mL) to target small conducting airways, whereas fine particles (~ 2 µm) achieve drug targeting in the region at a relatively higher flow rate (~ 500 mL/s) and similar tidal volume (~ 110 mL).ConclusionThe simulation results indicated that controlling tidal volume and flow rate can achieve targeted delivery to the small airways (i.e., > 50% of emitted dose was predicted to deposit in the small airways), and the optimal parameters depend on the particle size. It is hoped that this finding could provide a means of improving drug targeting to the small conducting airways and improve prognosis in COPD management.

Microscopic Small Airway Abnormalities Identified in Early Idiopathic Pulmonary Fibrosis InVivo Using Endobronchial Optical Coherence Tomography.

Rationale: Idiopathic pulmonary fibrosis (IPF) affects the subpleural lung but is considered to spare small airways. Micro-computed tomography (micro-CT) studies demonstrated small airway reduction in end-stage IPF explanted lungs, raising questions about small airway involvement in early-stage disease. Endobronchial optical coherence tomography (EB-OCT) is a volumetric imaging modality that detects microscopic features from subpleural to proximal airways. Objectives: In this study, EB-OCT was used to evaluate small airways in early IPF and control subjects invivo. Methods: EB-OCT was performed in 12 subjects with IPF and 5 control subjects (matched by age, sex, smoking history, height, and body mass index). Subjects with IPF had early disease with mild restriction (FVC: 83.5% predicted), which was diagnosed per current guidelines and confirmed by surgical biopsy. EB-OCT volumetric imaging was acquired bronchoscopically in multiple, distinct, bilateral lung locations (total: 97 sites). IPF imaging sites were classified by severity into affected (all criteria for usual interstitial pneumonia present) and less affected (some but not all criteria for usual interstitial pneumonia present). Bronchiole count and small airway stereology metrics were measured for each EB-OCT imaging site. Measurements and Main Results: Compared with the number of bronchioles in control subjects (mean = 11.2/cm3; SD = 6.2), there was significant bronchiole reduction in subjects with IPF (42% loss; mean = 6.5/cm3; SD = 3.4; P = 0.0039), including in IPF affected (48% loss; mean: 5.8/cm3; SD: 2.8; P < 0.00001) and IPF less affected (33% loss; mean: 7.5/cm3; SD: 4.1; P = 0.024) sites. Stereology metrics showed that IPF-affected small airways were significantly larger, more distorted, and more irregular than in IPF-less affected sites and control subjects. IPF less affected and control airways were statistically indistinguishable for all stereology parameters (P = 0.36-1.0). Conclusions: EB-OCT demonstrated marked bronchiolar loss in early IPF (between 30% and 50%), even in areas minimally affected by disease, compared with matched control subjects. These findings support small airway disease as a feature of early IPF, providing novel insight into pathogenesis and potential therapeutic targets.

Control status and follow-up of acute attacks in children with bronchial asthma with normal pulmonary ventilation function

To investigate the control status of bronchial asthma (referred to as "asthma") in school-age children with normal pulmonary ventilation function and the occurrence of acute attacks within 1 year of follow-up. A retrospective analysis was conducted on clinical data of 327 children aged 6-14 years with bronchial asthma and normal pulmonary ventilation function from April to September 2021. Based on the measured value of one second rate (FEV1/FVC), the children were divided into the ≥80% group (267 cases) and the <80% group (60 cases). The pulmonary ventilation function, asthma control level, and occurrence of acute attacks within 1 year were compared between the two groups. The baseline pulmonary ventilation function in the <80% group was lower than that in the ≥80% group, and the proportion of small airway dysfunction was higher than that in the ≥80% group (P<0.05). After standardized treatment for 1 year, the small airway function indices in the <80% group improved but remained lower than those in the ≥80% group (P<0.05). The rate of incomplete asthma control at baseline was 34.6% (113/327), and the asthma control level in the <80% group was lower than that in the ≥80% group (P<0.05). After standardized treatment for 1 year, the asthma control level in the <80% group remained lower than that in the ≥80% group, and the proportion of acute asthma attacks was higher than that in the ≥80% group (P<0.05). Approximately one-third of school-age children with asthma still have incomplete asthma control when their pulmonary ventilation function is normal. Among them, children with measured FEV1/FVC<80% have an increased risk of acute asthma attacks and require close follow-up and strengthened asthma management.

Long COVID symptoms after 8-month recovery: persistent static lung hyperinflation associated with small airway dysfunction

BackgroundLimited research has investigated the relationship between small airway dysfunction (SAD) and static lung hyperinflation (SLH) in patients with post-acute sequelae of COVID-19 (PASC) especially dyspnea and fatigue.Methods64 patients with PASC were enrolled between July 2020 and December 2022 in a prospective observational cohort. Pulmonary function tests, impulse oscillometry (IOS), and symptom questionnaires were performed two, five and eight months after acute infection. Multivariable logistic regression models were used to test the association between SLH and patient-reported outcomes.ResultsSLH prevalence was 53.1% (34/64), irrespective of COVID-19 severity. IOS parameters and circulating CD4/CD8 T-cell ratio were significantly correlated with residual volume to total lung capacity ratio (RV/TLC). Serum CD8 + T cell count was negatively correlated with forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) with statistical significance. Of the patients who had SLH at baseline, 57% continued to have persistent SLH after eight months of recovery, with these patients tending to be older and having dyspnea and fatigue. Post-COVID dyspnea was significantly associated with SLH and IOS parameters R5-R20, and AX with adjusted odds ratios 12.4, 12.8 and 7.6 respectively. SLH was also significantly associated with fatigue.ConclusionSAD and a decreased serum CD4/CD8 ratio were associated with SLH in patients with PASC. SLH may persist after recovery from infection in a substantial proportion of patients. SAD and dysregulated T-cell immune response correlated with SLH may contribute to the development of dyspnea and fatigue in patients with PASC.

Detailed characterization and impact of small airway dysfunction in school-age asthma

Background Small airway dysfunction (SAD) is increasingly recognized as an important feature of pediatric asthma yet typically relies on spirometry-derived FEF25–75 to detect its presence. Multiple breath washout (MBW) and oscillometry potentially offer improved sensitivity for SAD detection, but their utility in comparison to FEF25–75, and correlations with clinical outcomes remains unclear for school-age asthma. We investigated SAD occurrence using these techniques, between-test correlation and links to clinical outcomes in 57 asthmatic children aged 8–18 years. Methods MBW and spirometry abnormality were defined as z-scores above/below ± 1.96, generating MBW reference equations from contemporaneous controls (n = 69). Abnormal oscillometry was defined as > 97.5th percentile, also from contemporaneous controls (n = 146). Individuals with abnormal FEF25–75, MBW, or oscillometry were considered to have SAD. Results Using these limits of normal, SAD was present on oscillometry in 63% (resistance at 5–20 Hz; R5-R20; >97.5th percentile), on MBW in 54% (Scond; z-scores> +1.96) and in spirometry FEF25–75 in 44% of participants (z-scores< −1.96). SAD, defined by oscillometry and/or MBW abnormality, occurred in 77%. Among those with abnormal R5-R20, Scond was abnormal in 71%. Correlations indicated both R5-R20 and Scond were linked to asthma medication burden, baseline FEV1 and reversibility. Additionally, Scond correlated with FENO and magnitude of bronchial hyper-responsiveness. SAD, detected by oscillometry and/or MBW, occurred in almost 80% of school-aged asthmatic children, surpassing FEF25–75 detection rates. Conclusions Discordant oscillometry and MBW abnormality suggests they reflect different aspects of SAD, serving as complementary tools. Key asthma clinical features, like reversibility, had stronger correlation with MBW-derived Scond than oscillometry-derived R5-R20.

An Ovine Model Yields Histology and Gene Expression Changes Consistent with Laryngotracheal Stenosis.

Animal models for laryngotracheal stenosis (LTS) are critical to understand underlying mechanisms and study new therapies. Current animal models for LTS are limited by small airway sizes compared to human. The objective of this study was to develop and validate a novel, large animal ovine model for LTS. Sheep underwent either bleomycin-coated polypropylene brush injury to the subglottis (n = 6) or airway stent placement (n = 2) via suspension microlaryngoscopy. Laryngotracheal complexes were harvested 4 weeks following injury or stent placement. For the airway injury group, biopsies (n = 3 at each site) were collected of tracheal scar and distal normal regions, and analyzed for fibrotic gene expression. Lamina propria (LP) thickness was compared between injured and normal areas of trachea. No mortality occurred in sheep undergoing airway injury or stent placement. There was no migration of tracheal stents. After protocol optimization, LP thickness was significantly increased in injured trachea (Sheep #3: 529.0 vs. 850.8 um; Sheep #4: 933.0 vs. 1693.2 um; Sheep #5: 743.7 vs. 1378.4 um; Sheep #6: 305.7 vs. 2257.6 um). A significant 62-fold, 20-fold, 16-fold, 16-fold, and 9-fold change of COL1, COL3, COL5, FN1, and TGFB1 was observed in injured scar specimen relative to unaffected airway, respectively. An ovine LTS model produces histologic and transcriptional changes consistent with fibrosis seen in human LTS. Airway stent placement in this model is safe and feasible. This large airway model is a reliable and reproducible method to assess the efficacy of novel LTS therapies prior to clinical translation. N/A Laryngoscope, 134:4239-4245, 2024.

Clinical efficacy of bronchoalveolar lavage in the treatment of small airway diseases in children.

This study aimed to evaluate the efficacy of bronchoalveolar lavage (BAL) in the treatment of children with small airway diseases. Children [n = 112; boys: 76, girls: 36 (ratio 2.1:1); age range: 1 month-10 years; median age: 12 months] with small airway diseases diagnosed by high-resolution computed tomography (HRCT) were enrolled in this study. The patients were assigned to either the BAL group (BAL and conventional therapy) or the control group (conventional therapy only). The duration of cough, fever, wheezing, hospitalization duration, disease course before admission, treatment cost, HRCT recovery time, and re-hospitalization rate were compared between the two groups. The median disease course before admission of the BAL group patients was longer than that of the controls (p = 0.006). The duration of cough and wheezing in the BAL group was significantly longer than that in the control group (p = 0.012 and p = 0.001, respectively). The recovery time of cough, the re-hospitalization rate, and the total expenditure incurred for the BAL group were lower than those for the control group (p = 0.027, p = 0.026, and p = 0.000, respectively). At 2 months after discharge, the small airway lesions were found to be absorbed in 86.2% of BAL group patients vs. 64.1% of control group patients. At 6 months after discharge, the lesions were not fully absorbed in 3.4% of the BAL group patients compared to 20.5% in the control group patients. BAL is suitable for patients with a long disease course before admission, a long duration of coughing, and recurrent wheezing. BAL treatment of small airway diseases in children can promote the disappearance of clinical symptoms, accelerate the improvement of imaging, reduce the rate of re-hospitalization, and reduce the cost of treatment.

Pulmonary Function, Computed Tomography Lung Abnormalities, and Small Airway Disease after COVID-19: 3-, 6-, and 9-Month Follow-Up.

Background/Objectives: Coronavirus disease 2019 (COVID-19) course may differ among individuals-in particular, those with comorbidities may have severe pneumonia, requiring oxygen supplementation or mechanical ventilation. Post-COVID-19 long-term structural changes in imaging studies can contribute to persistent respiratory disturbance. This study aimed to investigate COVID-19 sequels affecting the possibility of persistent structural lung tissue abnormalities and their influence on the respiratory function of peripheral airways and gas transfer. Methods: Patients were divided into two groups according to severity grades described by the World Health Organization. Among the 176 hospitalized patients were 154 patients with mask oxygen supplementation and 22 patients with high-flow nasal cannula (HFNC) or mechanical ventilation. All tests were performed at 3, 6, and 9 months post-hospitalization. Results: Patients in the severe/critical group had lower lung volumes in FVC, FVC%, FEV1, FEV1%, LC, TLC%, and DLCO% at three months post-hospitalization. At 6 and 9 months, neither group had significant FVC and FEV1 value improvements. The MEF 25-75 values were not significantly higher in the mild/moderate group than in the severe/critical group at three months. There were weak significant correlations between FVC and FEV1, MEF50, MEF 75, plethysmography TLC, disturbances in DLCO, and total CT abnormalities in the severe/critical group at three months. In a mild/moderate group, there was a significant negative correlation between the spirometry, plethysmography parameters, and CT lesions in all periods. Conclusions: Persistent respiratory symptoms post-COVID-19 can result from fibrotic lung parenchyma and post-infectious stenotic small airway changes not visible in CT, probably due to persistent inflammation.

Particles in Exhaled Air (PExA): Clinical Uses and Future Implications.

Access to distal airway samples to assess respiratory diseases is not straightforward and requires invasive procedures such as bronchoscopy and bronchoalveolar lavage. The particles in exhaled air (PExA) device provides a non-invasive means of assessing small airways; it captures distal airway particles (PEx) sized around 0.5-7 μm and contains particles of respiratory tract lining fluid (RTLF) that originate during airway closure and opening. The PExA device can count particles and measure particle mass according to their size. The PEx particles can be analysed for metabolites on various analytical platforms to quantitatively measure targeted and untargeted lung specific markers of inflammation. As such, the measurement of distal airway components may help to evaluate acute and chronic inflammatory conditions such as asthma, chronic obstructive pulmonary disease, acute respiratory distress syndrome, and more recently, acute viral infections such as COVID-19. PExA may provide an alternative to traditional methods of airway sampling, such as induced sputum, tracheal aspirate, or bronchoalveolar lavage. The measurement of specific biomarkers of airway inflammation obtained directly from the RTLF by PExA enables a more accurate and comprehensive understanding of pathophysiological changes at the molecular level in patients with acute and chronic lung diseases.

NF-κB/RelA signaling in secretoglobin progenitors mediates plasticity and MMP-induced barrier disruption in house dust mite-induced allergic asthma.

The mechanisms how aeroallergens induce sensitization are incompletely understood. The house dust mite (HDM) Dermatophagoides pteronyssius (Der p) is a ubiquitous aeroallergen that represents a major cause of allergic rhinitis and asthma. Herein, we tested whether HDM-induced aeroallergen exposure sensitivity is caused by the innate-immune response in small airway epithelial cells. HDM exposure is a rapid activator of NF-κB/RelA in the Secretoglobin (Scgb1a1+) lineage associated with upregulation of NF-κB/RelA-dependent markers of epithelial plasticity. To determine the effect of epithelial NF-κB signaling, NF-κB was depleted in a tamoxifen (TMX)-inducible Scgb1a1-CreERTM mouse within a CL57B/L6 background. Corn oil or TMX-treated/RelA-depleted [RelA knockdown (KD)] mice were repetitively exposed to airway HDM challenges to induce airway hyperresponsiveness (AHR). Strikingly, we observed that HDM induces hallmarks of epithelial plasticity through upregulation of the mesenchymal core factors SNAI1 and ZEB1 and production of metalloproteinase (MMP)9 that are RelA-dependent. Downstream, HDM-induced mucous metaplasia, Th2 polarization, allergen sensitivity, and airway hyperreactivity were all reduced in the RelA-depleted mice. Mechanistically, HDM-induced functional and structural barrier disruption was dependent on RelA signaling and associated with active MMP secretion into the bronchoalveolar lavage fluid. To establish the role of MMP2/9 in barrier disruption, we observe that a small-molecule MMP inhibitor (SB-3CT) blocked HDM-induced barrier disruption and activation of plasticity in naïve wild-type (WT) mice. Loss of functional barrier was associated with MMP disruption of zona occludens (ZO)-1 containing adherens junctions. Overall, this data indicates that host innate signaling in the Scgb1a1+ progenitors is directly linked to epithelial plasticity, MMP9 secretion, and enhanced barrier permeability that allows allergen penetration, sensitization producing allergic asthma (AA) in vivo. We propose that maintenance of epithelial integrity may reduce allergic sensitization and AA.NEW & NOTEWORTHY Allergic asthma from house dust mite (HDM) allergy causes substantial morbidity. This study examines the dynamic changes in small airway epithelial cells in a mouse model of HDM exposure. Our findings indicate that NF-κB/RelA signaling mediates matrix metalloproteinase production, disrupting the epithelial barrier resulting in allergic sensitization. Our findings bring new insight into mechanisms for epithelial cell-state change in the allergen response, creating a potential therapeutic pathway for maintaining barrier function in asthma.