Endoscopic Resection and Mucosal Reconstitution With Epidermal Grafting: A Pilot Study in Idiopathic Subglottic Stenosis

[Idiopathic Subglottic Tracheal Stenosis]

Idiopathic subglottic stenosis is a circular scarred narrowing of the airway at the transition from the cricoid cartilage to the trachea. The stenosis is found radiologically and endoscopically at the level of the cricoid cartilage without involvement of the cricoid or tracheal cartilage itself. The disease practically only affects women between the ages of 20 and 60. The same clinical picture occurs in granulomatosis with polyangiitis and less frequently in other autoimmune diseases, where it requires systemic treatment. The clinical picture usually begins insidiously with coughing and sputum production and leads to dyspnoea and a restricted cough. As the course is insidious and the patients are otherwise healthy, the symptoms are often misinterpreted and the diagnosis is delayed. Treatment consists of local measures, ranging from dilatation and laser surgical resection, sometimes with local application of medication to inhibit the proliferation of new scar tissue, to laryngotracheal resection of varying degrees. The disease is located in the border area between the trachea and larynx and the patients are therefore treated by ENT medicine, pneumology and thoracic surgery.

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

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

LEVEL OF EVIDENCE

N/A Laryngoscope, 2024.

A Comprehensive Flow Cytometry Panel for Analysis of Idiopathic Subglottic Stenosis

OBJECTIVE

To present a comprehensive flow cytometry panel for idiopathic subglottic stenosis (iSGS).

STUDY DESIGN

Controlled ex vivo cohort study.

SETTING

Tertiary care academic hospital in a metropolitan area.

METHODS

Flow cytometry and single-cell RNA sequencing were performed on 9 paired normal and scar tissue samples from iSGS patients. Flow cytometry was used to assess the presence of myeloid (CD11b, CD14, CD15, Siglec8), lymphoid (CD3, CD4, CD8, gamma delta [γδ], FOXP3), endothelial (CD31), fibroblast (CD90, SMA), and epithelial (CD326, CK5) markers.

RESULTS

On flow cytometry, iSGS scar is characterized by an increased presence of myeloid, lymphoid, endothelial, and fibroblast cell types, but a decreased presence of epithelial cells. In the myeloid lineage, iSGS scar samples demonstrated increased CD11b+ monocytes (P < .001), Siglec8+ eosinophils (P = .03), and CD14+ monocytes (P = .02). In the lymphoid lineage, iSGS scar demonstrated increased CD3+ T-cells (P < .001), CD4+ helper T-cells (P < .001), γδ+ T-cells (P < .001), and FOXP3+ regulatory T-cells (P = .002). iSGS scar exhibited specific increases in CD90+ (P = .04) and SMA+ (P < .001) fibroblasts but decreased CD326+ (E-cadherin) epithelial cells (P = .01) relative to normal samples.

CONCLUSION

We present a comprehensive flow cytometry panel for iSGS. This flow panel may serve as a common platform among airway scientists to elucidate the cellular mechanisms underpinning iSGS and other upper airway pathologies. Scar iSGS samples demonstrate a distinct cellular profile relative to normal iSGS specimens, exhibiting increased fibroblast, endothelial, and inflammatory cell types but decreased epithelium.

Does Idiopathic Subglottic Stenosis Length and Location Change with Serial Endoscopic Interventions?

OBJECTIVES/HYPOTHESIS

The aim was to assess changes in physical parameters of subglottic stenosis (SGS) following serial endoscopic surgical intervention.

STUDY DESIGN

This was a retrospective chart review.

METHODS

A retrospective review of 52 idiopathic subglottic stenosis (iSGS) patients undergoing multiple endoscopic (excision/dilation) procedures between 2014 and 2022 was completed. Parameters including proximal stenosis distance from the vocal process and total stenosis length collected intraoperatively were compared over serial treatments. Differences between patient variables affecting distances from the vocal process and mean stenosis length were statistically analyzed utilizing nonparametric estimators including the Mann Whitney U, Fisher exact, and linear regression models.

RESULTS

For the cohort of iSGS patients (N = 52), the mean age was 55.1 (±15.1). The patients were predominantly female (96.2%) and Caucasian (84.6%). Patients underwent an average of 3.4 (±1.3) endoscopic procedures for long-term treatment of iSGS (range: 1 to 5 procedures). Patients undergoing a total of two (2) total procedures within the data collection window demonstrated a statistically significant decrease in mean stenosis length between the first and second procedures (p = 0.014). Changes in distance of the stenosis from the glottis was not found to be statistically significant (p = 0.833). There was a statistically significant decrease in mean length of stenosis from the 1st to the 2nd procedure by approximately 0.11 cm (p = 0.0003). No additional statistically significant differences in stenosis length or location were detected.

CONCLUSIONS

Serial endoscopic excision/dilation procedures (the mainstay of iSGS surgical management) do not appear to significantly lengthen intraluminal stenosis nor change the distance of the stenosis from the glottis.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:1769-1772, 2024.

Decision-Making in the Treatment of Idiopathic Subglottic Stenosis: A Survey of Laryngologists

OBJECTIVE

Idiopathic subglottic stenosis (iSGS) is a rare condition involving the subglottic larynx and upper trachea, commonly affecting Caucasian females between 30 and 50 years of age. Despite its homogeneous presentation, clinical management for iSGS is yet to be standardized, leading to variability in outcomes between predominant interventions. In recognition of the heterogenicity in iSGS treatment and the need to improve patient outcomes, this study aimed to survey laryngologists to understand the factors influencing clinical decision-making and the incorporation of new treatment modalities for iSGS.

METHODS

An online survey was sent to 145 academic laryngologists. The survey assessed respondents' professional backgrounds, experience treating iSGS, treatment algorithms, and how various patient factors affect management.

RESULTS

Of the 87 (60%) laryngologists who responded to the survey, the most common clinical assessments were tracheoscopy/bronchoscopy (96.8%) and pulmonary function tests (43.6%). Endoscopic dilation (ED) was the most common primary treatment offered (97.5%): 28.7% of surveyed laryngologists offer SISI as a primary treatment, and 74.7% perform SISI as a planned postoperative treatment. The most common SISI protocol was repeated injections every 4-6 weeks for a series of 1-3 total injections. Notably, 9.2% perform the Maddern procedure. Routine algorithms of care involving surgery were most often based on prior experience and prior patient outcomes (75.9%) and conversations with colleagues (64.4%). Only 31% report using the same protocol learned during their fellowship training.

CONCLUSION

This survey highlights significant variation in the management of patients with iSGS. Understanding the factors that influence decision-making may lead to potential standardization in heterogeneous treatment approaches and may improve clinical outcomes.

LEVEL OF EVIDENCE

5 Laryngoscope, 134:865-872, 2024.

Dysfunctional Epithelial Barrier Is Characterized by Reduced E-Cadherin in Idiopathic Subglottic Stenosis

OBJECTIVES

To aim of the study was to characterize the molecular profile and functional phenotype of idiopathic subglottic stenosis (iSGS)-scar epithelium.

METHODS

Human tracheal biopsies from iSGS scar (n = 6) and matched non-scar (n = 6) regions were analyzed using single-cell RNA sequencing (scRNA-seq). Separate specimens were used for epithelial cell expansion in vitro to assess average growth rate and functional capabilities using transepithelial-electrical resistance (TEER), fluorescein isothiocyanate-dextran flux permeability assay, ciliary coverage, and cilia beating frequency (CBF). Finally, epithelial tight junction protein expression of cultured cells was quantified using immunoblot assay (n = 4) and immunofluorescence (n = 6).

RESULTS

scRNA-seq analysis revealed a decrease in goblet, ciliated, and basal epithelial cells in the scar iSGS cohort. Furthermore, mRNA expression of proteins E-cadherin, claudin-3, claudin-10, occludin, TJP1, and TJP2 was also reduced (p < 0.001) in scar epithelium. Functional assays demonstrated a decrease in TEER (paired 95% confidence interval [CI], 195.68-890.83 Ω × cm2 , p < 0.05), an increase in permeability (paired 95% CI, -6116.00 to -1401.99 RFU, p < 0.05), and reduced epithelial coverage (paired 95% CI, 0.1814-1.766, fold change p < 0.05) in iSGS-scar epithelium relative to normal controls. No difference in growth rate (p < 0.05) or CBF was found (paired 95% CI, -2.118 to 3.820 Hz, p > 0.05). Immunoblot assay (paired 95% CI, 0.0367-0.605, p < 0.05) and immunofluorescence (paired 95% CI, 13.748-59.191 mean grey value, p < 0.05) revealed E-cadherin reduction in iSGS-scar epithelium.

CONCLUSION

iSGS-scar epithelium has a dysfunctional barrier and reduced structural protein expression. These results are consistent with dysfunctional epithelium seen in other airway pathology. Further studies are warranted to delineate the causality of epithelial dysfunction on the downstream fibroinflammatory cascade in iSGS.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:374-381, 2024.

Murine Model of Airway Fibrosis has Anatomic, Physiologic, and Molecular Congruency to Human iSGS

OBJECTIVE

To narrow knowledge gaps in the pathophysiology of idiopathic subglottic stenosis (iSGS) through comparison of a murine subglottic stenosis model with iSGS.

STUDY DESIGN

In vivo animal study.

SETTING

Academic institution.

METHODS

Murine samples/measurements were obtained from mice that underwent chemomechanical injury with a wire brush and bleomycin. Human samples/measurements were obtained from iSGS patients. Anatomic, physiologic, and epithelial molecular data were collected using histology, human peak expiratory flow (PEF) and murine airway conductance, gene expression analysis with quantitative polymerase chain reaction, and protein analysis with quantitative immunohistochemistry.

RESULTS

Anatomic patterns of scars at the subglottis and proximal trachea seen in the murine model are similar to iSGS patients. Subglottic stenosis (SGS) mice had a decrease (P = .0194) in airway conductance compared to healthy controls, similar to a decrease (P = .0001) in predilation PEF versus postdilation in iSGS patients. There was decreased epithelial gene expression of E-cadherin (ECAD) (P < 0.01), occludin (OCLN) (P < .01), and cytokeratin-5 (CK5) (P < .05) and protein expression of ECAD (H/M: P < .001), OCLN (H: P < 0.05, M: P < .001), and CK5 (H: P < .001, M: P < .01) in murine SGS and iSGS versus controls.

CONCLUSION

The murine SGS model shows anatomic, physiologic, and molecular congruency with human iSGS, making it a reasonable model to investigate iSGS. The molecular similarities in epithelial barrier dysfunction suggest it may best be suited to explore epithelial mechanisms of iSGS and therapies directed at epithelial reconstitution. This model provides a foundation to collect data that will improve understanding of iSGS, and, ultimately, translate into more accurate animal models for future use.

The Evolution and Outcomes of the "Maddern Procedure" for the Treatment of Subglottic Stenosis

INTRODUCTION

A novel technique to treat subglottic stenosis, the "Maddern Procedure", has been gaining acceptance in academic centers. This study describes the technique in detail, as well as its evolution over the first 28 patients performed at an academic center.

METHODS

A prospective case-series, with descriptive technique modifications cataloged throughout the 6 years needed to accumulate the patient cohort with a minimum of 2 years of follow-up (11/2015-11/2021). Main outcomes examined included changes to surgical indications, complications, and post-operative outcomes as measured by validated measures of voice and breathing.

RESULTS

Complete resection of subglottic scaring was performed, at first transcervically (2 pts), then transorally (26 pts). Successful performance of the procedure occurred in all patients without complications, with either successful decannulation of previously existing tracheotomies, or removal of perioperative tracheotomies. Buccal grafts (8/26) replaced skin graft as the graft of choice. Although high subglottic disease was first thought to be a contraindication, superior results became evident in cases of high stenosis rather than disease that included the upper trachea, with 4/26 patients requiring subsequent tracheal resection or tracheal dilation. Of the 22 remaining patients, 19/22 had successful arresting of restenosis, with 2/22 undergoing subsequent cricotracheal resection, and 1/22 pts requiring subglottic dilation. Overall, 19/26 Maddern pts (73%) had objectively favorable outcomes, with 24/26 (92%) reporting that they would have undergone the procedure again.

CONCLUSION

Full-thickness mucosal resection and relining of the subglottis is a developing technique that is a safe, yet technically challenging procedure which addresses the recurrent nature of the disease.

LEVEL OF EVIDENCE

Level 4 (Case-series) Laryngoscope, 133:3100-3108, 2023.

Laryngotracheal Reconstruction for Subglottic and Tracheal Stenosis

Laryngotracheal stenosis is the common endpoint for any process that results in the narrowing of the airway at the level of the glottis, subglottis, or trachea. Although endoscopic procedures are effective in opening the airway lumen, open resection and reconstruction can be necessary to reconstitute a functional airway. When resection and anastomosis are insufficient due to extensive length or location of the stenosis, autologous grafts can be used to expand the airway. Future directions in airway reconstruction include tissue engineering and allotransplantation.

Endoscopic management of adult subglottic stenosis: an alternative to open surgery

PURPOSE

Various surgical techniques could be used to treat subglottic stenosis (SGS). The aim of this study is to present our experience in endoscopic management of SGS and show the impact of symptoms' evaluation, clinical examination and spirometry in the therapeutic decision.

METHODS

Endoscopic treatment was performed in patients referred for SGS and consisted of CO₂ scar lysis associated with balloon dilation and concomitant steroids' injection for patients with grade II or higher on the mMRC (modified Medical Research Council) dyspnea scale associated with a DI (Dyspnea Index) score higher than 10/40 and objective stenosis equal or higher than grade II. The preoperative DI score, EDI (expiratory disproportion index) and voice parameters were compared to postoperative results. The mean interval between endoscopic procedures (IEP) was calculated and we looked for the evolution of the IEP during repeated procedures.

RESULTS

Nineteen patients were included. 35 dilations were performed. The mean IEP was 86 weeks. There was a significant decrease of the postoperative DI scores by 18.6 points ± 11 (SD). An important difference of 20.1 ± 13.5 (SD) was identified between the pre and postoperative EDI. Minimal changes occured in voice parameters.

CONCLUSIONS

Endoscopic treatment with CO₂ scar lysis associated with balloon dilation and concomitant steroids' injection is a safe, reliable and minimally invasive endoscopic procedure to treat SGS. Decision to treat has to be on an individual basis taking into account subjective symptoms including Dyspnea Index score and objective laryngoscopic findings and spirometry.

Exploiting the potential of lung stem cells to develop pro-regenerative therapies

Acute and chronic lung diseases are a leading cause of morbidity and mortality globally. Unfortunately, these diseases are increasing in frequency and we have limited treatment options for severe lung diseases. New therapies are needed that not only treat symptoms or slow disease progression, but also enable the regeneration of functional lung tissue. Both airways and alveoli contain populations of epithelial stem cells with the potential to self-renew and produce differentiated progeny. Understanding the mechanisms that determine the behaviour of these cells, and their interactions with their niches, will allow future generations of respiratory therapies that protect the lungs from disease onset, promote regeneration from endogenous stem cells or enable regeneration through the delivery of exogenous cells. This review summarises progress towards each of these goals, highlighting the challenges and opportunities of developing pro-regenerative (bio)pharmaceutical, gene and cell therapies for respiratory diseases.

Corticosteroid Use in Otolaryngology: Current Considerations During the COVID-19 Era

OBJECTIVE

To offer pragmatic, evidence-informed advice on administering corticosteroids in otolaryngology during the coronavirus disease 2019 (COVID-19) pandemic, considering therapeutic efficacy, potential adverse effects, susceptibility to COVID-19, and potential effects on efficacy of vaccination against SARS-CoV-2, which causes COVID-19.

DATA SOURCES

PubMed, Cochrane Library, EMBASE, CINAHL, and guideline databases.

REVIEW METHODS

Guideline search strategies, supplemented by database searches on sudden sensorineural hearing loss (SSNHL), idiopathic facial nerve paralysis (Bell's palsy), sinonasal polyposis, laryngotracheal disorders, head and neck oncology, and pediatric otolaryngology, prioritizing systematic reviews, randomized controlled trials, and COVID-19-specific findings.

CONCLUSIONS

Systemic corticosteroids (SCSs) reduce long-term morbidity in individuals with SSNHL and Bell's palsy, reduce acute laryngotracheal edema, and have benefit in perioperative management for some procedures. Topical or locally injected corticosteroids are preferable for most other otolaryngologic indications. SCSs have not shown long-term benefit for sinonasal disorders. SCSs are not a contraindication to vaccination with COVID-19 vaccines approved by the US Food and Drug Administration. The Centers for Disease Control and Prevention noted that these vaccines are safe for immunocompromised patients.

IMPLICATIONS FOR PRACTICE

SCS use for SSNHL, Bell's palsy, laryngotracheal edema, and perioperative care should follow prepandemic standards. Local or topical corticosteroids are preferable for most other otolaryngologic indications. Whether SCSs attenuate response to vaccination against COVID-19 or increase susceptibility to SARS-CoV-2 infection is unknown. Immunosuppression may lower vaccine efficacy, so immunocompromised patients should adhere to recommended infection control practices. COVID-19 vaccination with Pfizer-BioNTech, Moderna, or Johnson & Johnson vaccines is safe for immunocompromised patients.