Malfunction of airway basal stem cells plays a crucial role in pathophysiology of tracheobronchopathia osteoplastica

Bronchoscopic Intervention for Tracheobronchopathia Osteochondroplastica: A Report of Two Cases

Tracheobronchopathia osteochondroplastica (TO) is an uncommon non-malignant tracheal ailment characterized by the existence of numerous bone and/or cartilage nodules in the submucosa of the trachea and bronchi. At present, there is a lack of standardized treatment recommendations for TO. This article presents two instances of severe tracheal stenosis caused by TO, which were effectively managed through the implementation of bronchoscopic stent placement and rigid bronchoscopy curettage, respectively. Both cases exhibited favorable outcomes, providing novel insights and references for the treatment of TO. Laryngoscope, 134:3093-3095, 2024.

Airway disease decreases the therapeutic potential of epithelial stem cells

BACKGORUND

Tissue-engineered tracheal grafts (TETG) can be recellularized by the host or pre-seeded with host-derived cells. However, the impact of airway disease on the recellularization process is unknown.

METHODS

In this study, we determined if airway disease alters the regenerative potential of the human tracheobronchial epithelium (hTBE) obtained by brushing the tracheal mucosa during clinically-indicated bronchoscopy from 48 pediatric and six adult patients.

RESULTS

Our findings revealed that basal cell recovery and frequency did not vary by age or region. At passage 1, all samples produced enough cells to cellularize a 3.5 by 0.5 cm2 graft scaffold at low cell density (~ 7000 cells/cm2), and 43.75% could cellularize a scaffold at high cell density (~ 100,000 cells/cm2). At passage 2, all samples produced the number of cells required for both recellularization models. Further evaluation revealed that six pediatric samples (11%) and three (50%) adult samples contained basal cells with a squamous basal phenotype. These cells did not form a polarized epithelium or produce differentiated secretory or ciliated cells. In the pediatric population, the squamous basal cell phenotype was associated with degree of prematurity (< 28 weeks, 64% vs. 13%, p = 0.02), significant pulmonary history (83% vs. 34%, p = 0.02), specifically with bronchopulmonary dysplasia (67% vs. 19%, p = 0.01), and patients who underwent previous tracheostomy (67% vs. 23%, p = 0.03).

CONCLUSIONS

In summary, screening high-risk pediatric or adult population based on clinical risk factors and laboratory findings could define appropriate candidates for airway reconstruction with tracheal scaffolds.

LEVEL OF EVIDENCE

Level III Cohort study.

Human apical-out nasal organoids reveal an essential role of matrix metalloproteinases in airway epithelial differentiation

Extracellular matrix (ECM) assembly/disassembly is a critical regulator for airway epithelial development and remodeling. Airway organoid is widely used in respiratory research, yet there is limited study to indicate the roles and mechanisms of ECM organization in epithelial growth and differentiation by using in vitro organoid system. Moreover, most of current Matrigel-based airway organoids are in basal-out orientation where accessing the apical surface is challenging. We present a human apical-out airway organoid using a biochemically defined hybrid hydrogel system. During human nasal epithelial progenitor cells (hNEPCs) differentiation, the gel gradually degrade, leading to the organoid apical surfaces facing outward. The expression and activity of ECM-degrading enzymes, matrix metalloproteinases (MMP7, MMP9, MMP10 and MMP13) increases during organoid differentiation, where inhibition of MMPs significantly suppresses the normal ciliation, resulting in increased goblet cell proportion. Moreover, a decrease of MMPs is found in goblet cell hyperplastic epithelium in inflammatory mucosa. This system reveals essential roles of epithelial-derived MMPs on epithelial cell fate determination, and provides an applicable platform enabling further study for ECM in regulating airway development in health and diseases.

Building and validating an artificial intelligence model to identify tracheobronchopathia osteochondroplastica by using bronchoscopic images

BACKGROUND

Given the rarity of tracheobronchopathia osteochondroplastica (TO), many young doctors in primary hospitals are unable to identify TO based on bronchoscopy findings.

OBJECTIVES

To build an artificial intelligence (AI) model for differentiating TO from other multinodular airway diseases by using bronchoscopic images.

DESIGN

We designed the study by comparing the imaging data of patients undergoing bronchoscopy from January 2010 to October 2022 by using EfficientNet. Bronchoscopic images of 21 patients with TO at Anhui Chest Hospital from October 2019 to October 2022 were collected for external validation.

METHODS

Bronchoscopic images of patients with multinodular airway lesions (including TO, amyloidosis, tumors, and inflammation) and without airway lesions in the First Affiliated Hospital of Guangzhou Medical University were collected. The images were randomized (4:1) into training and validation groups based on different diseases and utilized for deep learning by convolutional neural networks (CNNs).

RESULTS

We enrolled 201 patients with multinodular airway disease (38, 15, 75, and 73 patients with TO, amyloidosis, tumors, and inflammation, respectively) and 213 without any airway lesions. To find multinodular lesion images for deep learning, we utilized 2183 bronchoscopic images of multinodular lesions (including TO, amyloidosis, tumor, and inflammation) and compared them with images without any airway lesions (1733). The accuracy of multinodular lesion identification was 98.9%. Further, the accuracy of TO detection based on the bronchoscopic images of multinodular lesions was 89.2%. Regarding external validation (using images from 21 patients with TO), all patients could be diagnosed with TO; the accuracy was 89.8%.

CONCLUSION

We built an AI model that could differentiate TO from other multinodular airway diseases (mainly amyloidosis, tumors, and inflammation) by using bronchoscopic images. The model could help young physicians identify this rare airway disease.

Airway epithelium regeneration by photoactivated basal cells

The airway epithelium is the footstone to maintain the structure and functions of lung, in which resident basal cells (BCs) maintain homeostasis and functional regeneration of epithelial barrier in response to injury. In recent clinical researches, transplanting BCs has shown great inspiring achievements in therapy of various lung diseases. In this study, we report a noninvasive optical method to activate BCs for airway epithelium regeneration in vivo by fast scanning of focused femtosecond laser on BCs of airway epithelium to active Ca2+ signaling and subsequent ERK and Wnt pathways. The photoactivated BCs present high proliferative capacity and maintain high pluripotency, which enables them to plant in the injured airway epithelium and differentiate to club cells for regeneration of epithelium. This optical method can also work in situ to activate localized BCs in airway tissue. Therefore, our results provide a powerful technology for noninvasive BC activation in stem-cell therapy of lung diseases.

Tracheobronchopathia osteochondroplastica: clinical, bronchoscopic, and comorbid features in a case series

Background

Tracheobronchopathia osteochondroplastica (TO) is a rare condition of unknown etiology. TO is characterized by submucosal nodules, with or without calcifications, protruding in the anterolateral walls of the trachea and proximal bronchi. The objective of this study was to describe TO features and associated comorbidities in a series of patients.

Methods

Patients suffering from TO were retrospectively included by investigators from the Groupe d’Endoscopie Thoracique et Interventionnelle Francophone (GETIF). Demographic, clinical, comorbidities, bronchoscopic, functional, and radiological characteristics, and outcomes were recorded and analyzed.

Results

Thirty-six patients were included (69% male with a mean of 65 ± 12 years). Chronic symptoms were described by 81% of patients including cough (74%) and dyspnea on exertion (74%). TO was associated with COPD in 19% of the cases and gastroesophageal reflux disease in 6%. A mild to severe airflow obstruction was present in 55% of the cases. CT scan showed tracheal submucosal nodules in 93% of patients and tracheal stenosis in 17%. Bronchoscopy identified TO lesions in the trachea in 65% of the cases, and 66% of them were scattered. A bronchoscopic reevaluation was performed in 7 cases, 9 ± 14 months [1–56] after initial diagnosis, and showed the stability of lesions in all cases. Three patients underwent interventional bronchoscopic treatment.

Conclusion

The diagnosis of TO relies on typical bronchoscopic findings and can be evoked on a CT scan. Histologic diagnosis can be useful in atypical cases for differential diagnosis. Given its low consequences in terms of symptoms, lung functions, and evolution, no treatment is usually required.