Gene expression profiles in COVID-19-associated tracheal stenosis indicate persistent anti-viral response and dysregulated retinol metabolism.

INTRODUCTION: Coronavirus disease 2019 (COVID-19)-associated tracheal stenosis (COATS) may occur as a result of prolonged intubation during COVID-19 infection. We aimed to investigate patterns of gene expression in the tracheal granulation tissue of patients with COATS, leverage gene expression data to identify dysregulated cellular pathways and processes, and discuss potential therapeutic options based on the identified gene expression profiles. METHODS: Adult patients (age ≥ 18 years) presenting to clinics for management of severe, recalcitrant COATS were included in this study. RNA sequencing and differential gene expression analysis was performed with transcriptomic data for normal tracheal tissue being used as a control. The top ten most highly upregulated and downregulated genes were identified. For each of these pathologically dysregulated genes, we identified key cellular pathways and processes they are involved in using Gene Ontology (GO) and KEGG (Kyoto Encyclopedia of Genes and Genomes) applied via Database for Annotation, Visualization, and Integrated Discovery (DAVID). RESULTS: Two women, aged 36 years and 37 years, were included. The profile of dysregulated genes indicated a cellular response consistent with viral infection (CXCL11, PI15, CCL8, DEFB103A, IFI6, ACOD1, and DEFB4A) and hyperproliferation/hypergranulation (MMP3, CASP14 and HAS1), while downregulated pathways included retinol metabolism (ALDH1A2, RBP1, RBP4, CRABP1 and CRABP2). CONCLUSION: Gene expression changes consistent with persistent viral infection and dysregulated retinol metabolism may promote tracheal hypergranulation and hyperproliferation leading to COATS. Given the presence of existing literature highlighting retinoic acid's ability to favorably regulate these genes, improve cell-cell adhesion, and decrease overall disease severity in COVID-19, future studies must evaluate its utility for adjunctive management of COATS in animal models and clinical settings.

Identifying Molecular Pathophysiology and Potential Therapeutic Options in Iatrogenic Tracheal Stenosis.

INTRODUCTION: While most patients with iatrogenic tracheal stenosis (ITS) respond to endoscopic ablative procedures, approximately 15% experience a recalcitrant, recurring disease course that is resistant to conventional management. We aimed to explore genetic profiles of patients with recalcitrant ITS to understand underlying pathophysiology and identify novel therapeutic options. METHODS: We collected 11 samples of granulation tissue from patients with ITS and performed RNA sequencing. We identified the top 10 most highly up- and down-regulated genes and cellular processes that these genes corresponded to. For the most highly dysregulated genes, we identified potential therapeutic options that favorably regulate their expression. RESULTS: The dysregulations in gene expression corresponded to hyperkeratinization (upregulation of genes involved in keratin production and keratinocyte differentiation) and cellular proliferation (downregulation of cell cycle regulating and pro-apoptotic genes). Genes involved in retinoic acid (RA) metabolism and signaling were dysregulated in a pattern suggesting local cellular RA deficiency. Consequently, RA also emerged as the most promising potential therapeutic option for ITS, as it favorably regulated seven of the ten most highly dysregulated genes. CONCLUSION: This is the first study to characterize the role of hyperkeratinization and dysregulations in RA metabolism and signaling in the disease pathophysiology. Given the ability of RA to favorably regulate key genes involved in ITS, future studies must explore its efficacy as a potential therapeutic option for patients with recalcitrant ITS.

Reconstruction of Anterior Tracheal Defects Using a Bioengineered Graft in a Porcine Model.

BACKGROUND: Reconstruction of long-segment tracheal defects can be challenging and a suitable tracheal substitute remains lacking. We sought to create a bioengineered tracheal graft to repair such lesions using acellullar bovine dermis extracellular matrix (ECM) and male human mesenchymal stem cells (hMSCs) and implant it in a porcine model. METHODS: hMSCs were seeded on the ECM and incubated for 1 week with chondrogenic factors. An anterior 4 cm × 3 cm defect was surgically created in the trachea of 4-week-old female Yorkshire pigs. The defect was reconstructed using the bioengineered graft (n = 7) or control (n = 3, ECM only). The study duration was 3 months. RESULTS: Survival ranged from 7 days (n = 3) to 3 months (n = 7). Early death was due to graft malacia (n = 1, control), graft infection (n = 1, bioengineered), and pneumonia (n = 1, bioengineered). There was substantial animal growth at 3 months (>200% weight). Surveillance bronchoscopy showed patent airway, mild stenosis, and integration of the graft with the native trachea. On histology, luminal epithelialization and neovascularization with scant submucosa were observed in both the bioengineered graft and control groups. Chondrogenesis was seen only in the bioengineered graft. The neocartilage was less mature and organized compared to native cartilage. SRY immunostain was positive in the neocartilage but not control or native trachea. CONCLUSIONS: We demonstrate the feasibility of the bioengineered graft for reconstruction of long anterior tracheal defects with favorable short-term outcomes. Furthermore, we show its ability to facilitate chondrogenesis, neovascularization, and epithelialization. Importantly, it supported rapid animal growth offering potential solutions for both pediatric and adult applications.

Circumferential Three-Dimensional-Printed Tracheal Grafts: Research Model Feasibility and Early Results.

BACKGROUND: Methods for tracheal graft research have presented persistent challenges to investigators, and three-dimensional (3D)-printed biosynthetic grafts offer one potential development platform. We aimed to develop an efficient research platform for customizable circumferential 3D-printed tracheal grafts and evaluate feasibility and early structural integrity with a large-animal model. METHODS: Virtual 3D models of porcine subject tracheas were generated using preoperative computed tomography scans. Two designs were used to test graft customizability and the limits of the construction process. Designs I and II used 270-degree and 360-degree external polycaprolactone scaffolds, respectively, both encompassing a circumferential extracellular matrix collagen layer. The polycaprolactone scaffolds were made in a fused-deposition modeling 3D printer and customized to the recipient's anatomy. Design I was implanted in 3 pigs and design II in 2 pigs, replacing 4-ring tracheal segments. Data collected included details of graft construction, clinical outcomes, bronchoscopy, and gross and histologic examination. RESULTS: The 3D-printed biosynthetic grafts were produced with high fidelity to the native organ. The fabrication process took 36 hours. Grafts were implanted without immediate complication. Bronchoscopy immediately postoperatively and at 1 week demonstrated patent grafts and appropriate healing. All animals lived beyond a predetermined 1-week survival period. Bronchoscopy at 2 weeks showed significant paraanastomotic granulation tissue, which, along with partial paraanastomotic epithelialization, was confirmed on pathology. Overall survival was 17 to 34 days. CONCLUSIONS: We propose a rapid, reproducible, resource efficient method to develop various anatomically precise grafts. Further graft refinement and strategies for granulation tissue management are needed to improve outcomes.

Treatment of Benign Tracheal Stenosis Using Endoluminal Spray Cryotherapy.

Importance: Tracheal stenosis is a debilitating disorder with heterogeneity in terms of disease characteristics and management. Repeated recurrences substantially alter patients' quality of life. There is limited evidence for the use of spray cryotherapy (SCT) in the management of benign airway disease. Objective: To report our early results for the use of SCT in patients with benign tracheal stenosis. Design, Setting, and Participants: Data were extracted from the medical records of a consecutive series of patients with benign airway stenosis secondary to granulomatosis with polyangiitis (GPA) (n = 13), prior tracheotomy or tracheal intubation (n = 8), and idiopathic strictures (n = 5) treated from September 1, 2013, to September 30, 2015, at a tertiary care hospital. Main Outcomes and Measures: Airway narrowing was quantified on a standard quartile grading scale. Response to treatment was assessed by improvement in airway caliber and the time interval for reintervention. Exposures: Delivery of 4 5-second SCT cycles and 2 balloon dilatations. Results: Twenty-six patients (median [range] age, 53 [16-83] years; 20 [77%] female) underwent 48 SCT sessions. Spray cryotherapy was successfully used without any substantial intraoperative or postoperative complications in all patients. In a median (range) follow-up of 11 (1-26) months, all patients had improvement in symptoms. Before the institution of SCT, 23 patients (88%) had grade III or IV stenosis. At the last evaluation after induction of SCT, 4 (15%) had grade III or IV stenosis, with a mean (SD) change of 1.39 (0.51) (P < .001). Patients with GPA required significantly fewer SCT procedures (mean [SD], 1.38 [0.96] vs 2.31 [1.18]; P = .03) during the study period. Conclusions and Relevance: Spray cryotherapy was a safe adjunct modality to accomplish airway patency in patients with benign tracheal stenosis. Although efficacy evidence is limited for SCT, it may be useful for patients who have experienced treatment failure with conventional modalities. Further analysis of this cohort will determine the physiologic durability of the reported short-term changes. Additional trials are warranted for further evaluation of this modality.

Effectiveness of rituximab for the otolaryngologic manifestations of granulomatosis with polyangiitis (Wegener's).

OBJECTIVE: Ear, nose, and throat (ENT) involvement is the most prevalent manifestation of granulomatosis with polyangiitis (Wegener's) (GPA) and correlates with permanent damage and decreased quality of life. Although prior studies have evaluated the efficacy of rituximab (RTX) for granulomatous features of GPA, none have evaluated its efficacy solely for ENT manifestations. We compared the effectiveness of RTX to other therapies for the ENT manifestations of GPA in a large, well-characterized cohort. METHODS: We performed a retrospective analysis of 975 visits from 99 GPA patients seen at a tertiary care ENT practice between 2003 and 2013. At each visit, subjects had a complete ENT examination, with ENT activity assessed by a single expert otolaryngologist. ENT disease activity during the observational period in subjects receiving RTX was compared to subjects receiving all other therapy. RESULTS: In total, 48 subjects had never received RTX and 51 received RTX at least once. There was no active ENT disease during 92.4% of the observational period (days) for subjects receiving RTX, compared with 53.7% of the observational period for subjects not receiving RTX (odds ratio 11.0 [95% confidence interval 5.5­22.0], P < 0.0001). Subjects receiving RTX, compared with those receiving methotrexate, azathioprine, cyclophosphamide, or trimethoprim-sulfamethoxazole, were significantly more likely to have no active ENT disease (P < 0.0001 for each comparison). CONCLUSION: RTX is an effective treatment for ENT manifestations of GPA. Subjects treated with RTX were significantly less likely to have active ENT disease compared with those not receiving RTX. Patients being treated with RTX were 11 times less likely to have active ENT disease than patients being treated with other therapies.

Timely airway stenting improves survival in patients with malignant central airway obstruction.

BACKGROUND: The survival of patients with malignant central airway obstruction is very limited. Although airway stenting results in significant palliation of symptoms, data regarding improved survival after stenting for advanced thoracic cancer with central airway obstruction are lacking. METHODS: Fifty patients received a total of 72 airway stents for malignant central airway obstruction over a two-year period at a single institution. The Medical Research Council (MRC) dyspnea scale and Eastern Cooperative Oncology Group (ECOG) performance status were used to divide patients into a poor performance group (MRC = 5, ECOG = 4) and an intermediate performance group (MRC ≤ 4, ECOG ≤ 3). The SPSS version 16.0 (SPSS Inc, Chicago, IL) and Microsoft Excel (Microsoft, Redmond, WA) were used to analyze the data. Survival curves were constructed using the Kaplan-Meier survival analysis method and a log-rank test was used to compare the survival distributions among different groups. RESULTS: Successful patency of the airway was achieved in all patients with no procedure-related mortality. Stenting resulted in significant improvement in MRC and ECOG performance scores (p < 0.01). Significantly improved survival was observed only in patients in the intermediate performance group compared with patients in the poor performance group (p < 0.05). CONCLUSIONS: Airway stenting resulted in significant palliation of symptoms in both groups as evaluated by MRC dyspnea scale and ECOG performance status. Compared with historic controls, a significant survival advantage was seen only in the intermediate performance group. We postulate that timely stenting of the airway, before the morbid complications of malignant central airway obstruction have set in, results in improved survival.

Endoscopic tracheoplasty: segmental tracheal ring resection in a porcine model.

Endoscopic tracheoplasty is used for the relief of airway obstruction because of several benign conditions such as postintubation stenosis, inflammatory disorders such as Wegener granulomatosis, and benign neoplastic processes. Several endoscopic treatment modalities exist for these conditions, all with good initial results. However, recurrence is common and often requires frequent reintervention. Endoscopic segmental tracheal ring resection is a novel therapeutic approach that could potentially provide a durable solution. Endoscopic segmental tracheal ring resection was performed in 3 Yorkshire pigs under general anesthesia. A combination of bipolar cautery and sharp dissection was used to resect 25% to 33% of the circumference of a single tracheal ring. Technical success was achieved in all 3 animals with no intraoperative complications. Full-thickness excision, including the anterior perichondrium, was performed in 1 animal without violation of the pretracheal fascia, with no subcutaneous emphysema or clinically apparent pneumothorax. Average operative time was 31 minutes and estimated blood loss was minimal. Heart rate, oxygen saturation, and peak airway pressures were maintained within normal ranges during the procedure and for the 60-minute postoperative period. Histologic analysis of the resected specimen confirmed complete thickness excision of the segment of tracheal cartilage. Endoscopic tracheoplasty by segmental tracheal ring resection is a safe and feasible technique in a porcine model. Long-term durability could potentially outlast other endoscopic techniques for the treatment of bening tracheal stenosis. Survival studies in a porcine model of tracheal stenosis must be performed to assess the long-term outcomes of this approach.