Idiopathic subglottic stenosis is associated with activation of the inflammatory IL-17A/IL-23 axis

Laser Versus Cold Steel for Endoscopic Management of Subglottic Stenosis

OBJECTIVE

Endoscopic management of subglottic stenosis (SGS) includes a wide range of techniques. This 17-year review compares treatment outcomes between carbon dioxide (CO2) laser and cold steel.

STUDY DESIGN

Retrospective chart review.

SETTING

Single tertiary care center.

METHODS

A chart review was performed for all patients undergoing endoscopic treatment of SGS at Cleveland Clinic between July 12, 2000 and September 1, 2017. Data collected included demographics, stenosis etiology, stenosis severity, comorbidities, treatment modality, and airway procedure history. The primary endpoint was repeated treatment-free survival (RTFS) within 2 years using a Kaplan-Meier analysis and Cox proportional hazard model.

RESULTS

A total of 139 patients (median [interquartile range] aged 48.7 [37.8, 57.0] years; 83.4% female) were included in the analysis, with etiologies including idiopathic (56.8%), granulomatosis with polyangiitis (25.2%), and intubation (16.5%). All patients underwent either cold steel (107 patients) or CO2 laser (32 patients) lysis of stenosis with concurrent dilation. RTFS within 2 years was 50.2% for CO2 laser and 31.9% for cold steel (hazard ratio [HR] and 95% confidence interval [CI]: 1.69, 0.96-2.97, P = .07). In patients with no prior airway procedures, there was no difference in RTFS between laser and cold knife (P = .41). However, in patients with prior airway procedures, RTFS was significantly greater in the laser group, even after adjusting for age, smoking history, and stenosis etiology (50.0% vs 16.8%, adjusted HR and CI: 2.82, 1.14-6.98, P = .025).

CONCLUSION

Endoscopic lysis of SGS with CO2 laser should be considered in revision cases.

Transcriptional profiling sheds light on the fibrotic aspects of idiopathic subglottic tracheal stenosis

Idiopathic subglottic stenosis (ISGS) is a rare fibrotic disease of the upper trachea with an unknown pathomechanism. It typically affects adult Caucasian female patients, leading to severe airway constrictions caused by progressive scar formation and inflammation with clinical symptoms of dyspnoea, stridor and potential changes to the voice. Endoscopic treatment frequently leads to recurrence, whereas surgical resection and reconstruction provides excellent long-term functional outcome. This study aimed to identify so far unrecognized pathologic aspects of ISGS using single cell RNA sequencing. Our scRNAseq analysis uncovered the cellular composition of the subglottic scar tissue, including the presence of a pathologic, profibrotic fibroblast subtype and the presence of Schwann cells in a profibrotic state. In addition, a pathology-associated increase of plasma cells was identified. Using extended bioinformatics analyses, we decoded pathology-associated changes of factors of the extracellular matrix. Our data identified ongoing fibrotic processes in ISGS and provide novel insights on the contribution of fibroblasts, Schwann cells and plasma cells to the pathogenesis of ISGS. This knowledge could impact the development of novel approaches for diagnosis and therapy of ISGS.

Lipoaspirate Injection in Relapsing Idiopathic Subglottic Stenosis: Preliminary Results

OBJECTIVES

The management of idiopathic subglottic stenosis (iSGS) poses a clinical challenge due to high recurrence rates following both endoscopic and open approaches, often leading to tracheostomy. The activation of abnormal T-cells and cytokine pathways has been linked to iSGS pathogenesis. Autologous adipose tissue centrifugation yields lipoaspirate, offering optimal anti-inflammatory effects and biocompatibility widely utilized in various medical settings. This report presents the first 3 cases employing endoscopic dilation (ED) in combination with local lipoaspirate injection to address recurrent iSGS.

METHODS

A prospective observational study was conducted, involving multidisciplinary evaluation by the Tracheal Team at the University of Modena. Patients meeting specific criteria were directed to undergo ED + lipoaspirate injection.

RESULTS

Three patients fulfilled the inclusion criteria. The mean number of prior endoscopic procedures performed was 8. Endoscopic examination revealed 90% stenosis in patient A, 60% stenosis in patient B, and 60% stenosis in patient C. All patients presented inflammatory tissue or incipient granulations at the stenotic site, with an average time of 6 months between previous procedures. After 15 months, none of the patients required further procedures, and endoscopic examination revealed a significant reduction or disappearance of inflammatory tissue with a stable airway lumen.

CONCLUSIONS

The observed results are encouraging in terms of reducing local inflammation and halting stenosis progression, especially in cases of short-term relapsing iSGS.

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.

Characterizing the T Cell Repertoire in the Proximal Airway in Health and Disease

OBJECTIVES

Recent translational scientific efforts in subglottic stenosis (SGS) support a disease model where epithelial alterations facilitate microbiome displacement, dysregulated immune activation, and localized fibrosis. Given the observed immune cell infiltrate in SGS, we sought to test the hypothesis that SGS cases possessed a low diversity (highly clonal) adaptive immune response when compared with healthy controls.

METHODS

Single cell RNA sequencing (scRNA-seq) of subglottic mucosal scar in iSGS (n = 24), iLTS (n = 8), and healthy controls (n = 7) was performed. T cell receptor (TCR) sequences were extracted, analyzed, and used to construct repertoire structure, compare diversity, interrogate overlap, and define antigenic targets using the Immunarch bioinformatics pipeline.

RESULTS

The proximal airway mucosa in health and disease are equally diverse via Hill framework quantitation (iSGS vs. iLTS vs. Control, p > 0.05). Repertoires do not significantly overlap between individuals (Morisita <0.02). Among iSGS patients, clonality of the TCR repertoire is driven by CD8+ T cells, and iSGS patients possess numerous TCRs targeting viral and intercellular pathogens. High frequency clonotypes do not map to known targets in public datasets.

CONCLUSION

SGS cases do not possess a lower diversity adaptive immune infiltrate when compared with healthy controls. Interestingly, the TCR repertoire in both health and disease contains a restricted number of high frequency clonotypes that do not significantly overlap between individuals. The target of the high frequency clonotypes in health and disease remain unresolved.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:1757-1764, 2024.

Localizing Hormone Receptor Expression to Cellular Compartments in Idiopathic Subglottic Stenosis

OBJECTIVES

Idiopathic subglottic stenosis (iSGS) is an unexplained progressive fibrosis of the upper airway. iSGS almost exclusively affects women; as a result, female hormones (estrogen and progesterone) have been proposed to participate in the pathogenesis of iSGS. Our aim was to localize cell-specific gene expression of estrogen receptors (ESR1 and ESR2) and progesterone receptor (PGR) using an established iSGS single-cell RNA sequencing (scRNAseq) cell atlas.

STUDY DESIGN

Ex vivo molecular study of airway scar and healthy mucosa from iSGS patients.

METHODS

An established scRNAseq atlas consisting of 25,974 individually sequenced cells from subglottic scar (n = 7) or matched unaffected mucosa (n = 3) in iSGS patients was interrogated for RNA expression of ESR1, ESR2, and PGR. Results were quantified and compared across cell subsets, then visualized using Uniform Manifold Approximation and Projection (UMAP). Confirmatory protein assessment of endocrine receptors in fibroblasts from iSGS patients (n = 5) was performed via flow cytometry.

RESULTS

The proximal airway mucosa in iSGS patients demonstrates differential expression of endocrine receptors (ESR1, ESR2, PGR). Within airway scar, endocrine receptors are primarily expressed by fibroblasts, immune cells, and endothelial cells. Fibroblasts show strong ESR1 and PGR expression, while immune cells possess RNA for both ESR1 and ESR2. Endothelial cells predominantly express ESR2. Epithelial cells in unaffected mucosa express all three receptors, which are all reduced in airway scar.

CONCLUSIONS

scRNAseq data localized endocrine receptor expression to specific cell subsets. These results provide the foundation for future work interrogating how hormone-dependent mechanisms promote, sustain, or participate in iSGS disease pathogenesis.

LEVEL OF EVIDENCE

NA; Basic science Laryngoscope, 133:3506-3511, 2023.

Characteristics of Idiopathic Subglottic Stenosis in the Elderly

OBJECTIVE

To compare characteristics of patients ≥65 years presenting with idiopathic subglottic stenosis (iSGS) to patients diagnosed at <65 years. We hypothesize that the groups have similar comorbidities and disease courses.

DATA SOURCES

Medical records of patients treated for iSGS at a tertiary care institution from January 2005-September 2022.

REVIEW METHODS

Patient demographics, time from symptom onset to diagnosis, medical history and comorbidities, and treatment modalities/intervals were recorded and analyzed. Characteristics of patients ≥65 and <65 years at presentation were compared using Chi-square analysis for non-numeric values and the Mann-Whitney U-test for numeric values.

RESULTS

One hundred seven patients with iSGS were identified and 16 (15%) were aged ≥65 years (mean age 72.6, 15 female) at presentation. These patients were compared to 91 patients aged <65 years (mean age = 47.6, 90 female). Patients ≥65 years had higher rates of type 2 diabetes mellitus (T2DM) (p = 0.004) and tobacco use (p = 0.004). There were no significant differences in body mass index, gastroesophageal reflux disease, hormone replacement therapy, time from symptom onset to presentation, or length of operative treatment intervals.

CONCLUSION

Patients ≥65 years with iSGS have higher rates of tobacco use, suggesting that alterations in wound healing may play a role in the development of iSGS in this age group. Although rates of T2DM were higher in the elderly group, clinical significance may be limited given the overall higher rate of diabetes mellitus in the elderly population.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:3075-3079, 2023.

Mapping Genetic Susceptibility to Stenosis in the Proximal Airway

OBJECTIVES

Recent translational scientific efforts in subglottic stenosis (SGS) support a disease model where epithelial alterations facilitate microbiome displacement, dysregulated immune activation, and localized fibrosis. Yet despite recent advances, the genetic basis of SGS remains poorly understood. We sought to identify candidate risk genes associated with an SGS phenotype, investigate their biological function, and identify the cell types enriched for their expression.

METHODS

The Online Mendelian Inheritance in Man (OMIM) database was queried for single gene variants associated with an SGS phenotype. The functional intersections and molecular roles of the identified genes were explored using pathway enrichment analysis (PEA) computational methods. Cellular localization of the candidate risk genes was measured via transcriptional quantification in an established single cell RNA sequencing (scRNA-seq) atlas of the proximal airway.

RESULTS

Twenty genes associated with SGS phenotype were identified. PEA resulted in 24 significantly enriched terms including "cellular response to TGF-β," "epithelial-to-mesenchymal transition," and "adherens junctions." Mapping the 20 candidate risk genes to the scRNA-seq atlas found 3 (15%) genes were enriched in epithelial cells, 3 (15%) in fibroblasts, and 3 (15%) in endothelial cells. 11 (55%) genes were expressed ubiquitously among tissue types. Interestingly, immune cells were not significantly enriched for candidate risk genes.

CONCLUSION

We identify and provide biologic context for 20 genes associated with fibrotic disease of the proximal airway and form the foundation for future detailed genetic study.

LEVEL OF EVIDENCE

N/A Laryngoscope, 133:3049-3056, 2023.

Tracheal microbiome and metabolome profiling in iatrogenic subglottic tracheal stenosis

BACKGROUND

To study the role of microecology and metabolism in iatrogenic tracheal injury and cicatricial stenosis, we investigated the tracheal microbiome and metabolome in patients with tracheal stenosis after endotracheal intubation.

METHODS

We collected 16 protected specimen brush (PSB) and 8 broncho-alveolar lavage (BAL) samples from 8 iatrogenic subglottic tracheal stenosis patients, including 8 PSB samples from tracheal scar sites, 8 PSB samples from scar-free sites and 8 BAL samples, by lavaging the subsegmental bronchi of the right-middle lobe. Metagenomic sequencing was performed to characterize the microbiome profiling of 16 PSB and 8 BAL samples. Untargeted metabolomics was performed in 6 PSB samples (3 from tracheal scar PSB and 3 from tracheal scar-free PSB) using high-performance liquid chromatography‒mass spectrometry (LC‒MS).

RESULTS

At the species level, the top four bacterial species were Neisseria subflava, Streptococcus oralis, Capnocytophaga gingivals, and Haemophilus aegyptius. The alpha and beta diversity among tracheal scar PSB, scar-free PSB and BAL samples were compared, and no significant differences were found. Untargeted metabolomics was performed in 6 PSB samples using LC‒MS, and only one statistically significant metabolite, carnitine, was identified. Pathway enrichment analysis of carnitine revealed significant enrichment in fatty acid oxidation.

CONCLUSION

Our study found that carnitine levels in tracheal scar tissue were significantly lower than those in scar-free tissue, which might be a new target for the prevention and treatment of iatrogenic tracheal stenosis in the future.

Amelioration of Subglottic Stenosis by Antimicrobial Peptide Eluting Endotracheal Tubes

Introduction

Pediatric subglottic stenosis (SGS) results from prolonged intubation where scar tissue leads to airway narrowing that requires invasive surgery. We have recently discovered that modulating the laryngotracheal microbiome can prevent SGS. Herein, we show how our patent-pending antimicrobial peptide-eluting endotracheal tube (AMP-ET) effectively modulates the local airway microbiota resulting in reduced inflammation and stenosis resolution.

Materials and Methods

We fabricated mouse-sized ETs coated with a polymeric AMP-eluting layer, quantified AMP release over 10 days, and validated bactericidal activity for both planktonic and biofilm-resident bacteria against Staphylococcus aureus and Pseudomonas aeruginosa. Ex vivo testing: we inserted AMP-ETs and ET controls into excised laryngotracheal complexes (LTCs) of C57BL/6 mice and assessed biofilm formation after 24 h. In vivo testing: AMP-ETs and ET controls were inserted in sham or SGS-induced LTCs, which were then implanted subcutaneously in receptor mice, and assessed for immune response and SGS severity after 7 days.

Results

We achieved reproducible, linear AMP release at 1.16 µg/day resulting in strong bacterial inhibition in vitro and ex vivo. In vivo, SGS-induced LTCs exhibited a thickened scar tissue typical of stenosis, while the use of AMP-ETs abrogated stenosis. Notably, SGS airways exhibited high infiltration of T cells and macrophages, which was reversed with AMP-ET treatment. This suggests that by modulating the microbiome, AMP-ETs reduce macrophage activation and antigen specific T cell responses resolving stenosis progression.

Conclusion

We developed an AMP-ET platform that reduces T cell and macrophage responses and reduces SGS in vivo via airway microbiome modulation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-023-00769-9.

The role of local expression of hormone receptors in the genesis of idiopathic tracheal stenosis

Background

Tracheal stenosis in adults is usually the result of mechanical injuries either from direct trauma, tracheotomy or intubation. Idiopathic stenosis in the cricotracheal section is a rare condition and occurs almost exclusively in females. Therefore, an influence of the female sexual hormones estrogen and progesterone has been assumed previously.

Methods

Tracheal specimens of 27 patients who received tracheal resection for either idiopathic tracheal stenosis (ITS) (n=11) or posttraumatic tracheal stenosis (PTTS) (n=16) between 2008 and 2019 in our surgical department were included and retrospectively analyzed. Immunohistochemical staining of tracheal specimens concerning the hormone receptor status of progesterone and estrogen was performed.

Results

While post-tracheotomy stenosis occurred in males (n=6) as well as in females (n=10), none of the patients with idiopathic stenosis were males. All of the idiopathic stenosis (n=11; 100%) showed a strong expression of the estrogen receptors (ERs) in the fibroblasts and expression of progesterone receptors (PRs) in fibroblasts in 8 of 11 (72.7%). In the post-tracheotomy patients, only 3/16 (18.8%) showed slight staining of PRs and 6/16 (37.5%) of ERs. Of those, only one male patient presented with expression of ERs and PRs and another male patient presented with isolated PRs. Oral intake of hormone compounds was seen in 11/27 (40.7%) patients: 7/11 (63.6%) in the ITS group and 4/16 (25%) in the PTTS (noteworthy that the PTTS group included 6 male patients).

Conclusions

Although the number of patients is small, our results show that the expression of female sexual hormone receptors in the fibroblasts of the trachea is a persistent finding in ITS. Surgery provided good results with a favorable long-term outcome without recurrence of stenosis for ITS and PTTS. Further investigation with a special focus on hormones is needed to assist in the prevention of this rare disease.

Sirolimus-eluting airway stent reduces profibrotic Th17 cells and inhibits laryngotracheal stenosis

Laryngotracheal stenosis (LTS) is pathologic fibrotic narrowing of the larynx and trachea characterized by hypermetabolic fibroblasts and CD4+ T cell-mediated inflammation. However, the role of CD4+ T cells in promoting LTS fibrosis is unknown. The mTOR signaling pathways have been shown to regulate the T cell phenotype. Here we investigated the influence of mTOR signaling in CD4+ T cells on LTS pathogenesis. In this study, human LTS specimens revealed a higher population of CD4+ T cells expressing the activated isoform of mTOR. In a murine LTS model, targeting mTOR with systemic sirolimus and a sirolimus-eluting airway stent reduced fibrosis and Th17 cells. Selective deletion of mTOR in CD4+ cells reduced Th17 cells and attenuated fibrosis, demonstrating CD4+ T cells' pathologic role in LTS. Multispectral immunofluorescence of human LTS revealed increased Th17 cells. In vitro, Th17 cells increased collagen-1 production by LTS fibroblasts, which was prevented with sirolimus pretreatment of Th17 cells. Collectively, mTOR signaling drove pathologic CD4+ T cell phenotypes in LTS, and targeting mTOR with sirolimus was effective at treating LTS through inhibition of profibrotic Th17 cells. Finally, sirolimus may be delivered locally with a drug-eluting stent, transforming clinical therapy for LTS.

Can the Remote Use of a Peak Flow Meter Predict Severity of Subglottic Stenosis and Surgical Timing?

OBJECTIVE

We aimed to assess the relationship between patient-performed and patient-reported peak flow meter (PFM) measurements with pulmonary function testing (PFT) and Dyspnea Index (DI) scores as a tool for monitoring Subglottic stenosis (SGS) disease progression remotely.

METHODS

Thirty-five SGS patients were prospectively enrolled. Patients were given PFMs to report serial measurements from home. DI scores and PFT were recorded at serial clinic visits. Data were analyzed to determine the correlation between PFM measurements and PFT data. Pre-operative and post-operative PFM measurements, PFT, and DI scores were analyzed for patients who underwent operative intervention. Receiver operating characteristic (ROC) curves were created for PFM measurements, PFT data, and DI scores to predict the likelihood of surgery.

RESULTS

PFM measurements had a "strong" correlation with the peak expiratory flow rate (PEFR), r = 0.78. Means of PEFR, PIFR, EDI, PFM measurements, and DI scores all significantly improved after the operative intervention (p ≤ 0.05). The area under the curve for ROC curves for DI scores, PFM measurements, and EDI were highest in our cohort with values of 0.896, 0.823, and 0.806, respectively.

CONCLUSION

In our SGS cohort, PFM measurements correlate strongly with PEFR measurements. PFM measurements can adequately demonstrate disease progression and predict the need for surgery in this patient population. Together, DI scores and PFM measurements may be a useful tool to remotely follow patients with SGS and inform timing of in-person assessments.

LEVEL OF EVIDENCE

2 Laryngoscope, 133:628-633, 2023.

RNA Sequencing of Idiopathic Subglottic Stenosis Tissues Uncovers Putative Profibrotic Mechanisms and Identifies a Prognostic Biomarker

Idiopathic subglottic stenosis (iSGS) is a localized airway disease that almost exclusively affects females. Understanding the molecular mechanisms involved may provide insights leading to therapeutic interventions. Next-generation sequencing was performed on tissue sections from patients with iSGS (n = 22), antineutrophil cytoplasmic antibody-associated vasculitis (AAV; n = 5), and matched controls (n = 9) to explore candidate genes and mechanisms of disease. Gene expression changes were validated, and selected markers were identified by immunofluorescence staining. Epithelial-mesenchymal transition (EMT) and leukocyte extravasation pathways were the biological mechanisms most relevant to iSGS pathogenesis. Alternatively activated macrophages (M2) were abundant in the subepithelium and perisubmucosal glands of the airway in iSGS and AAV. Increased expression of the mesenchymal marker S100A4 and decreased expression of the epithelial marker epithelial cell adhesion molecule (EPCAM) further supported a role for EMT, but to different extents, in iSGS and antineutrophil cytoplasmic antibody-associated subglottic stenosis. In patients with iSGS, high expression of prostate transmembrane protein, androgen induced 1 (PMEPA1), an EMT regulator, was associated with a shorter recurrence interval (25 versus 116 months: hazard ratio = 4.16; P = 0.041; 95% CI, 1.056-15.60). Thus, EMT is a key pathogenetic mechanism of subglottic stenosis in iSGS and AAV. M2 macrophages contribute to the pathogenesis of both diseases, suggesting a shared profibrotic mechanism, and PMEPA1 may be a biomarker for predicting disease recurrence in iSGS.

Prognostic biomarker IL17A correlated with immune infiltrates in head and neck cancer

Background

The underlying functions and mechanisms of the Th17 pathway in Head and neck squamous cell carcinoma (HNSCC) progression and tumor immunology are still unclear. We investigated the correlation between IL17A expression and certain clinical parameters, tumor-infiltrating immune cells (TIICs) in TCGA HNSCC samples.

Methods

HNSCC files from the TCGA database were analyzed to obtain data on immune system infiltrates, gene expression, and related clinical information. R (Version 3.6.3) software, GEPIA, and TIMER online analysis tools were used to profile the relationship between the expression of IL17A and the prognosis, clinical stages, survival status and immune cell tumor-infiltrating levels of HNSCC patients. GEPIA and TIMER online analysis tools were used to verify the data.

Results

The expression of IL17A was significantly decreased in tumor tissues from HNSCC. IL17A expression was associated with M, N stage, lymphovascular invasion, and patients OS event. GSEA revealed that IL17A was closely related to humoral immune response, T cells response, and cytokine signal. TCGA database and TIMER online analysis indicated that the B cells and T cells levels were correlated with IL17A. The correlation between IL17A expression and correlated genes was analyzed.

Conclusions

IL-17A plays a key role in HNSCC. The levels of IL17A are important values for the determination of the occurrence and development of the HNSCC. The IL17A and correlated genes may be potential immunotherapeutic targets for HNSCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-022-02703-1.

Laryngotracheal stenosis: Mechanistic review

Background

The purpose of this review article is to summarize the existing literature surrounding wound healing mechanisms in laryngotracheal stenosis.

Methods

A review of general wound healing pathophysiology, followed by a focused review of iatrogenic laryngotracheal stenosis (iLTS) and idiopathic subglottic stenosis (iSGS) as conditions of aberrant wound healing.

Results

iLTS is the scarring of the laryngotracheal complex, coming secondary to injury from prolonged intubation. iSGS is a chronic fibroinflammatory scarring and narrowing of the subglottic airway in the absence of any obvious preceding injury or trauma. They are both thought to result from a prolonged and dysregulated wound healing response that promotes the deposition of pathologic scar in the airway.

Conclusions

Understanding the mechanisms that underlie wound healing will help identify and intervene on the process early in its development and discover future therapies that target individual wound healing mechanisms limiting the incidence of this recalcitrant disease process.

Molecular Mechanisms and Physiological Changes behind Benign Tracheal and Subglottic Stenosis in Adults

Laryngotracheal stenosis (LTS) is a complex and heterogeneous disease whose pathogenesis remains unclear. LTS is considered to be the result of aberrant wound-healing process that leads to fibrotic scarring, originating from different aetiology. Although iatrogenic aetiology is the main cause of subglottic or tracheal stenosis, also autoimmune and infectious diseases may be involved in causing LTS. Furthermore, fibrotic obstruction in the anatomic region under the glottis can also be diagnosed without apparent aetiology after a comprehensive workup; in this case, the pathological process is called idiopathic subglottic stenosis (iSGS). So far, the laryngotracheal scar resulting from airway injury due to different diseases was considered as inert tissue requiring surgical removal to restore airway patency. However, this assumption has recently been revised by regarding the tracheal scarring process as a fibroinflammatory event due to immunological alteration, similar to other fibrotic diseases. Recent acquisitions suggest that different factors, such as growth factors, cytokines, altered fibroblast function and genetic susceptibility, can all interact in a complex way leading to aberrant and fibrotic wound healing after an insult that acts as a trigger. However, also physiological derangement due to LTS could play a role in promoting dysregulated response to laryngo-tracheal mucosal injury, through biomechanical stress and mechanotransduction activation. The aim of this narrative review is to present the state-of-the-art knowledge regarding molecular mechanisms, as well as mechanical and physio-pathological features behind LTS.

Prolonged Surgical Interval Following Chemotherapy in a Patient With Idiopathic Subglottic Stenosis (iSGS): Case Report and Brief Review of Literature

Objective:

To report a case of a patient with idiopathic subglottic stenosis (iSGS) who no longer required surgical intervention for her disease following a chemotherapy regimen of carboplatin and doxorubicin for ovarian cancer. A brief review of the literature and discussion on the possible mechanism of action of chemotherapy agents affecting fibrosis is included.

Methods:

Case report and review of literature.

Results:

A 71-year-old Caucasian woman with iSGS was managed with serial endoscopic excision and dilation (n = 5) from 2013 to 2017 with an average dilation interval of 12.3 months. After a course of doxorubicin and carboplatin to treat her ovarian cancer, we observed that her airway stenosis surprisingly stabilized, and has no longer required a surgical dilation for 45 months, which signifies an increase of 33 months when compared to her averaged dilation interval (12.3 months) prior to her second course of chemotherapy.

Conclusion:

We present an iSGS patient whose fibrosis was arrested following carboplatin/doxorubicin treatment. While a single case, a possible mechanism is carboplatin/doxorubicin’s inhibition of pathologic CD4 lymphocytes that propagate laryngotracheal fibrosis. Further investigation of like mechanisms may allow for translation of local agents with inhibitory effects on CD4+ cells and/or fibroblasts as a novel therapy for airway fibrosis.

Case report: Idiopathic subglottic stenosis in a girl; successful treatment with macrolides

An 8-year-old girl presented with treatment-refractory cough and inspiratory stridor. Bronchoscopies showed progressive scarring leading to narrowing of the proximal trachea (Myer-Cotton Grade 2) and epithelial metaplasia of the tracheal and bronchial mucosa. After excluding other causes of congenital and acquired tracheal stenosis, an idiopathic subglottic tracheal stenosis (iSGS) was diagnosed. Because of the patient's young age, a judicious therapeutic approach seemed appropriate. Therapy with azithromycin, followed by roxithromycin, was started. Symptoms almost completely subsided, spirometry normalized, and endoscopic and histologic findings improved considerably. Therapy has been continued for more than 3 years with normal lung function values, and no compromise on physical activities and development. In instances of iSGS, therapy with macrolides is worth considering before more invasive procedures such as dilatation, laser, intralesional injections, or surgical resection are performed.

Prevalence and incidence of idiopathic subglottic stenosis in southern and central Alberta: a retrospective cohort study

Background

Subglottic stenosis (SGS) is a reportedly rare disease that causes recurrent severe airway obstruction. Etiologies reported for SGS include idiopathic, iatrogenic, autoimmune, congenital, and traumatic, with variable ratios among different centres. From empiric observation, southern and central Alberta was hypothesized to have a disproportionate distribution of SGS driven by increased idiopathic SGS (iSGS) compared to previous literature. Identification of causative agents of iSGS will help understand and guide future management options, so this study aimed to characterize the demographics of SGS subtypes, define prevalence and incidence rates of iSGS in southern Alberta, and geographically analyze for clustering of iSGS prevalence.

Methods

SGS patients from Alberta census divisions No. 1–9 and 15 were retrospectively reviewed. Patients were subtyped according to etiology of SGS and characterized. Idiopathic SGS prevalence and incidence was assessed; prevalence was further geographically segregated by census division and forward sortation area (FSA). Significant clustering patterns were assessed for using a Global Moran’s I analysis.

Results

From 2010 to 2019 we identified 250 SGS patients, who were substantially overrepresented by idiopathic patients (80.4%) compared to autoimmune (10.0%), iatrogenic (7.6%), congenital (1.2%), and traumatic (0.8%). The total iSGS prevalence was 9.28/100,000 with a mean annual incidence rate of 0.71/100,000 per year. Significant clustering was observed (Moran’s index 0.125; z-score 2.832; p = 0.0046) and the highest rates of prevalence were observed in southern Alberta and in rural communities heterogeneously dispersed around Calgary FSAs.

Conclusion

In southern and central Alberta, iSGS patients were disproportionately over-represented in contrast to other subtypes with the highest prevalence in southern Alberta. There was a three-fold higher annual incidence compared to previous literature demonstrating the highest rates of disease reported worldwide. Future research aims to expand the geographical scope and to assess for demographic or environmental differences within significant clusters that may contribute to disease pathophysiology.

Level of evidence

III.

Graphical Abstract

Quality and readability of online information on idiopathic subglottic stenosis

OBJECTIVE

Idiopathic subglottic stenosis (ISS) is a chronic condition characterized by disease recurrence and multiple surgeries. These frustrated patients may utilize the internet to research their condition. The aim of this study was to determine the quality and readability of online ISS information.

METHODS

"Idiopathic subglottic stenosis" was entered into Google. The first 50 websites that met inclusion criteria were extracted. The DISCERN instrument, Flesch Reading Ease Score (FRES), and Flesch-Kincaid Grade Level (FKGL) assessed the quality and readability, respectively. Means, SDs, Pearson correlation coefficients, and two-tailed Student's t-test were calculated.

RESULTS

The 50 websites consisted of 17 patient-targeted and 33 professional-targeted websites, plus 30 major and 20 minor websites. The overall DISCERN, FRES, and FKGL scores were 2.81 ± 0.99, 27.75 ± 15.27, and 13.65 ± 2.79, respectively (mean ± SD). Patient-targeted websites had significantly lower quality (DISCERN [P < .00]) but were easier to read (lower FKGL [P < .00], higher FRES [P < .00]) than professional-targeted websites. Minor websites had a significantly lower quality (DISCERN [P < 0.00]) but were easier to read (lower FKGL [P < .00], higher FRES [P < .00]) than major websites. There was a positive correlation between overall quality and difficulty in readability.

CONCLUSION

The quality of online ISS information was suboptimal. Resources were too difficult to comprehend and readability scores were above AMA and NIH recommendations. Improved online information is required to properly educate this patient population.

LEVEL OF EVIDENCE

Level 4.

Laryngeal Subsite Analysis of Granulomatosis With Polyangiitis (Wegener's)

Objective

To analyze specific intralaryngeal findings associated with granulomatosis with polyangiitis (GPA).

Study Design

Retrospective chart review.

Setting

Tertiary referral center.

Methods

A retrospective chart review was performed on all patients diagnosed with GPA who were evaluated at the laryngology division of Massachusetts Eye and Ear Infirmary between January 2006 and September 2019.

Results

Forty-four patients (14 male, 30 female) were evaluated for laryngeal pathology. The mean age at onset was 48 years. Nine patients (21%) were identified with only vocal fold disease, 11 (25%) with subglottic disease, and 8 (18%) with disease at the glottis and subglottis (transglottic). The remaining 16 patients (36%) had a normal airway upon examination although they presented with laryngeal symptoms. Patients with glottic disease had statistically significantly lower voice-related quality of life scores than patients with isolated subglottic stenosis.

Conclusions

Although laryngeal manifestations of GPA is often described as a subglottic disease presenting with respiratory symptoms, subsite analysis show that only 25% of patients had subglottic disease alone, with similar rates of glottic disease alone. Laryngeal subsites have different epithelial mucosa, function, and physiology, and understanding the specific sites of involvement will determine symptoms and enable better analysis of the underlying mechanisms of disease. Glottic disease is associated with a reduction in vocal fold motion and voice changes. Subglottic involvement presents more frequently with airway symptoms. Further research is necessary to better define the specific regions of laryngeal involvement in patients diagnosed with GPA.

Modeling Recurrence in Idiopathic Subglottic Stenosis With Mobile Peak Expiratory Flow

OBJECTIVES/HYPOTHESIS

We sought to establish normative peak expiratory flow (PEF) data for patients with idiopathic subglottic stenosis (iSGS), evaluate whether immediate changes in PEF after a procedure predict long-term treatment response, and test if a decline in longitudinal PEF is associated with disease recurrence.

STUDY DESIGN

International, prospective, 3-year multicenter cohort study of 810 patients with untreated, newly diagnosed, or previously treated iSGS.

METHODS

iSGS patients consented and enrolled in the North American Airway Collaborative (NoAAC) iSGS¹⁰⁰⁰ cohort recorded PEF data on a mobile smartphone app. Cox regression tested the associations between the magnitude of postoperative PEF improvement and longitudinal 90-day PEF decline with the risk of disease recurrence.

RESULTS

Within the NoAAC iSGS¹⁰⁰⁰ cohort, 810 patients participated in a 3-year prospective study comparing surgical treatment efficacy and 385 had appropriate PEF measurements and follow-up data. Of those patients, 42% (161/385) required at least one operation during study follow-up. The mean PEF preceding operative intervention was 241 L/min (95% confidence interval [CI]: 120-380) corresponding to a predicted PEF of 52%. The mean increase in PEF following a procedure was 111 L/min (95% CI: 96-125 L/min). Interestingly, the magnitude of immediate PEF improvement was not predictive of disease recurrence (hazard ratio [HR] for 100 L/min increase = 0.90, 95% CI: 0.60-1.00). However, recurrence was associated with the magnitude of PEF decline over 90 days (30% vs. 10% decline, HR = 2.2, 95% CI: 1.5-3.0).

CONCLUSIONS

We provide normative PEF data on a large iSGS patient cohort. The degree of PEF improvement immediately after surgery was not associated with a longer procedure-free interval. However, a 30% decline in PEF over 90 days was associated with elevated risk of disease recurrence.

LEVEL OF EVIDENCE

2 Laryngoscope, 2021.

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

OBJECTIVE

To describe technical aspects and surgical outcomes of endoscopic resection and mucosal reconstitution with epidermal grafting (ie, the Maddern procedure) in the treatment of idiopathic subglottic stenosis.

STUDY DESIGN

Medical record abstraction.

SETTING

Johns Hopkins Hospital.

METHODS

Retrospective series of 9 adults with idiopathic subglottic stenosis who underwent the Maddern procedure by a single surgeon over a 5-year period. Prespecified outcomes included (1) perioperative outcomes (Clavien-Dindo grade 4/5 complications, need for staged tracheostomy, hospital length of stay), (2) postoperative outcomes (peak expiratory flow rate [PEFR], need for subsequent airway surgery, tracheostomy at follow-up), and (3) patient-reported quality-of-life outcomes (Clinical COPD Questionnaire, Voice Handicap Index-10, Eating Assessment Tool-10, and 12-Item Short Form Version 2). Wilcoxon matched-pairs signed rank test and Kaplan-Meier analysis were performed.

RESULTS

There were no Clavien-Dindo grade 4/5 complications; 2 patients required unplanned staged tracheostomy; and the median length of stay was 3 days. Following endoscopic resection and stent removal, a median of 2 laser resurfacing procedures were required. Two patients developed recurrent stenosis requiring cricotracheal resection (CTR). There were significant improvements in PEFR, Clinical COPD Questionnaire, and Voice Handicap Index-10, without significant difference in Eating Assessment Tool-10. The 12-Item Short Form Version 2 approximated the population norm. Kaplan-Meier analysis demonstrated significant improvement in time to surgery after the final laser resurfacing.

CONCLUSION

The Maddern procedure has a low complication rate and offers durable physiologic improvement in PEFR, limiting need for additional procedures. Risks included need for CTR salvage, temporary tracheostomy, phlegm accumulation, and laryngospasm. It is a surgical option for patients with short dilation intervals who prefer to avoid the risks of CTR.

IL-17 signaling pathway plays a key role in laryngeal squamous cell carcinoma with ethnic specificity

Laryngeal squamous cell carcinoma (LSCC) is a common aggressive head and neck squamous cell carcinoma (HNSCC) and racial disparities have been reported to exist in it. However, its molecular mechanism and associated ethnic specificity are still unclear. Here, we leveraged mRNA expression data from 2 gene expression omnibus datasets (GSE142083 & GSE117005) of Chinese samples and the cancer genome atlas (TCGA) datasets of Caucasian samples to demonstrate the expression signature of LSCC. The GSE142083 dataset was used as the discovery set since it had 53 pairs of LSCC tissues and matched adjacent normal tissues, and the GSE117005 dataset was treated as the validation set with 5 pairs of tissues. Differential gene expression analysis and enrichment pathway analysis were performed. Besides, we employed weighted gene co-expression network analysis to identify hub genes in validated pathways. The TCGA datasets were used to evaluate ethnic specificity. Immunohistochemistry (IHC) was employed to further validate the hub gene. Overall, the IL-17 signaling pathway was significantly enriched for upregulated genes in two Chinese datasets while not in TCGA datasets; and IL17RC, MAPK3, S100A8, MMP3, CXCL8, and TNFA1P3 were hub genes regulating such pathway. Therein, IL17RC might be the most important one and the IHC results displayed that the IL17RC gene upregulated in the LSCC tissue. IL-17 signaling pathway has an ethnicity-specific effect in LSCC where it is upregulated in the Chinese while not in the Caucasians and IL17RC might play a key role. Targeting genes located in the IL-17 signaling pathway may be beneficial for Chinese LSCC patients.

Down-Regulation of a Profibrotic Transforming Growth Factor-β1/Cellular Communication Network Factor 2/Matrix Metalloprotease 9 Axis by Triamcinolone Improves Idiopathic Subglottic Stenosis

Idiopathic subglottic stenosis (iSGS) is a progressive fibrotic disease characterized by life-threatening airway narrowing. Although the molecular underpinnings are unknown, previous reports showing that subglottic serial intralesional steroid injections (SILSIs) improve clinical outcomes suggest a steroid-sensitive pathway in iSGS. Herein, a prospective study was conducted to determine the changes in profibrotic markers during SILSI to identify steroid-sensitive profibrotic drivers. Seven newly diagnosed patients with iSGS were recruited for SILSI. Subglottic biopsies before and after SILSI treatments were evaluated for histologic and molecular markers by confocal microscopy and RT-qPCR. At baseline, iSGS subglottises contained abundant vimentin-positive/α-smooth muscle actin-negative fibroblasts, intermingled with a matrix of fibronectin and types I and VI collagen. Transforming growth factor (TGF)-β1 was up-regulated primarily in glandular epithelium. Cellular communication network factor 2 (CCN2) was mainly up-regulated in stromal fibroblasts surrounding TGF-β1-positive glandular structures. SILSI improved iSGS by reducing fibroblast infiltration and increasing matrix remodeling. Mechanistically, SILSI counteracted the effects of TGF-β1 by inducing matrix metalloprotease 9 (MMP9) expression while repressing CCN2 expression, without affecting TGFβ1 levels. Treatment of primary iSGS-derived fibroblasts with TGF-β1 recapitulated aspects of the disease in vivo, demonstrating that the induction in CCN2 and repression of MMP9 are caused by changes in histone acetylation induced by TGF-β1. Triamcinolone counteracted the coregulation of these genes by impairing SMAD2/3 binding to promoter regions, and not through histone acetylation. In conclusion, this study shows that SILSI counteracts a dysregulated TGF-β1/CCN2/MMP9 axis involved in iSGS development.

Quantitative Assessment of the Immune Microenvironment in Patients With Iatrogenic Laryngotracheal Stenosis

OBJECTIVE

Iatrogenic laryngotracheal stenosis (iLTS) is characterized by fibroinflammatory narrowing of the upper airway and is most commonly caused by intubation injury. Evidence suggests a key role for CD4 T cells in its pathogenesis. The objective of this study is to validate emerging multiplex immunofluorescence (mIF) technology for use in the larynx and trachea while quantitatively characterizing the immune cell infiltrate in iLTS. In addition to analyzing previously unstudied immune cell subsets, this study aims to validate previously observed elevations in the immune checkpoint PD-1 and its ligand PD-L1 while exploring their spatial and cellular distributions in the iLTS microenvironment.

STUDY DESIGN

Controlled ex vivo cohort study.

SETTING

Tertiary care center.

METHODS

mIF staining was performed with formalin-fixed, paraffin-embedded slides from 10 patients with iLTS who underwent cricotracheal resection and 10 control specimens derived from rapid autopsy for CD4, CD8, CD20, FoxP3, PD-1, PD-L1, and cytokeratin.

RESULTS

There was greater infiltration of CD4+ T cells, CD8+ T cells, CD20+ B cells, FoxP3+CD4+ Tregs, and FoxP3+CD8+ early effector T cells in the submucosa of iLTS specimens as compared with controls (P < .05 for all). PD-1 was primarily expressed on T cells and PD-L1 predominantly on CD4+ cells and "other" cells.

CONCLUSION

This study leverages the power of mIF to quantify the iLTS immune infiltrate in greater detail. It confirms the highly inflammatory nature of iLTS, with CD4+ cells dominating the immune cell infiltrate; it further characterizes the cellular and spatial distribution of PD-1 and PD-L1; and it identifies novel immunologic targets in iLTS.

The Proximal Airway Is a Reservoir for Adaptive Immunologic Memory in Idiopathic Subglottic Stenosis

OBJECTIVES/HYPOTHESIS

Characterization of the localized adaptive immune response in the airway scar of patients with idiopathic subglottic stenosis (iSGS).

STUDY DESIGN

Basic Science.

METHODS

Utilizing 36 patients with subglottic stenosis (25 idiopathic subglottic stenosis [iSGS], 10 iatrogenic post-intubation stenosis [iLTS], and one granulomatosis with polyangiitis [GPA]) we applied immunohistochemical and immunologic techniques coupled with RNA sequencing.

RESULTS

iSGS, iLTS, and GPA demonstrate a significant immune infiltrate in the subglottic scar consisting of adaptive cell subsets (T cells along with dendritic cells). Interrogation of T cell subtypes showed significantly more CD69+ CD103+ CD8+ tissue resident memory T cells (TRM ) in the iSGS airway scar than iLTS specimens (iSGS vs. iLTS; 50% vs. 28%, P = .0065). Additionally, subglottic CD8+ clones possessed T-cell receptor (TCR) sequences with known antigen specificity for viral and intracellular pathogens.

CONCLUSIONS

The human subglottis is significantly enriched for CD8+ tissue resident memory T cells in iSGS, which possess TCR sequences proven to recognize viral and intracellular pathogens. These results inform our understanding of iSGS, provide a direction for future discovery, and demonstrate immunologic function in the human proximal airway. Laryngoscope, 131:610-617, 2021.

Voice and Swallowing Outcomes Following Airway Reconstruction in Adults: A Systematic Review

OBJECTIVES

Laryngotracheal stenosis is a rare condition characterized by upper airway narrowing. Reconstructive surgical treatment aims to manage the area of stenosis to improve dyspnea and can impact voice and swallowing function. This article critically evaluates the literature about voice and swallowing outcomes in adults with laryngotracheal stenosis who undergo reconstructive surgery.

STUDY DESIGN

Systematic review.

METHODS

Six databases were searched for articles referring to voice and swallowing outcome measures following reconstruction procedures in adults with laryngotracheal stenosis. Screening was completed using predefined inclusion/exclusion criteria.

RESULTS

A total of 143 abstracts were reviewed, with 67 articles selected for full-text review. Twenty studies met the inclusion criteria. Data extraction was completed with the Strengthening Reporting of Observational Studies in Epidemiology checklist with Oxford Centre for Evidence-Based Medicine Level of Evidence used to indicate quality. Risk of bias was assessed using the Risk of Bias Assessment Tool for Non-Randomized Studies. All studies scored a high risk of bias in at least one of the domains. Selection and timing of outcome measures was heterogenous, and there was limited information provided about rationale or reliability.

CONCLUSIONS

The literature acknowledges the importance of voice and swallowing outcomes following airway reconstruction. Studies show correlation between reconstructive surgery and deterioration in vocal function; there are no consistent data about swallowing outcomes. The lack of a core outcome measures set for adults with laryngotracheal stenosis limits the findings of this review. Further research is needed to establish clear criteria for robust and clinically relevant outcome measurement. Laryngoscope, 131:146-157, 2021.

M2 Macrophages Promote Collagen Expression and Synthesis in Laryngotracheal Stenosis Fibroblasts

OBJECTIVE

Macrophages exhibit distinct phenotypes and are dysregulated in a model of iatrogenic laryngotracheal stenosis (iLTS). Increased populations of alternatively activated or M2 macrophages have been demonstrated. However, the role of these macrophages is unknown. The aims of this study are: 1) define the macrophage population in iLTS in the context of classically activated or M1 and M2 macrophage phenotypes, and 2) characterize the effect of monocyte-derived M1 and M2 macrophages on normal airway and LTS-derived fibroblasts (FBs) in vitro.

STUDY DESIGN

Comparative analysis; in vitro controlled study.

METHODS

Immunohistochemical analysis of human iLTS and control specimens was performed to define the macrophage population. In vitro, M1, and M2 macrophages were polarized using M-CSF + Interferon-gamma and lipopolysaccharide or Interleukin-4, respectively. FBs isolated from laryngotracheal scar (LTS-FBs) and normal tracheal airway (NA-FBs) in eight patients with iLTS were cocultured with polarized macrophages. Fibrosis gene expression, soluble collagen production, and proliferation were assessed.

RESULTS

Immunohistochemical analysis revealed increased CD11b + cells (macrophage marker) in laryngotracheal scar specimens (18.3% vs. 8.5%, P = .03) and predominant CD206 (M2) costaining versus CD86 (M1) (51.5% vs. 9.8%, n = 10, P = .001). In vitro, NA-FBs cultured with M2 macrophages demonstrated a 2.41-fold increase in collagen-1 expression (P = .05, n = 8) and an increase in soluble collagen (9.98 vs. 8.875, mean difference: 1.11 95%, confidence interval 0.024-2.192, n = 8, P = .015).

CONCLUSION

Increased populations of CD11b cells are present in iLTS specimens and are predominantly CD206+, indicating an M2 phenotype. In vitro, M2 macrophages promoted collagen expression in airway FBs. Targeting macrophages may represent a therapeutic strategy for attenuating fibrosis in iLTS.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:E346-E353, 2021.

Proteomic and Genomic Methylation Signatures of Idiopathic Subglottic Stenosis

OBJECTIVE

Idiopathic subglottic stenosis (iSGS) is a chronic inflammatory condition that causes dyspnea and affects middle-aged women of White race and non-Latino or Hispanic ethnicity. To better characterize its phenotype and pathogenesis, we assessed the proteomic and genomic methylation signatures of subglottic tissue collected from iSGS patients compared to controls.

STUDY DESIGN

Molecular analysis of clinical biospecimens.

METHODS

We collected subglottic tissue biopsies from 12 patients during direct laryngoscopy, immediately prior to surgical treatment of iSGS; as well as from 4 age-, sex-, and race/ethnicity-matched control patients undergoing other direct laryngoscopic procedures. We isolated protein and genomic DNA, acquired proteomic data using label-free quantitative mass spectrometry techniques, and acquired genome-wide methylation data using bisulfite conversion and a microarray platform. We compared molecular profiles across the iSGS and control groups, and with respect to clinical course in the iSGS group. Eight of the 12 iSGS patients underwent subsequent blood collection and plasma isolation for further assessment.

RESULTS

Proteomic analysis revealed 42 differentially abundant proteins in the iSGS biopsies compared to controls, inferring enrichment of biological pathways associated with early wound healing, innate immunity, matrix remodeling, and metabolism. Proteome-based hierarchical clustering organized patients into two iSGS and one control subgroups. Methylation analysis revealed five hypermethylated genes in the iSGS biopsies compared to controls, including the biotin recycling enzyme biotinidase (BTD). Follow-up analysis showed elevated plasma BTD activity in iSGS patients compared to both controls and published normative data.

CONCLUSION

iSGS exhibits distinct proteomic and genomic methylation signatures. These signatures expand current understanding of the iSGS phenotype, support the possibility of disease subgroups, and should inform the direction of future experimental studies.

LEVEL OF EVIDENCE

Not applicable Laryngoscope, 131:E540-E546, 2021.

Increased Expression of PD-1 and PD-L1 in Patients With Laryngotracheal Stenosis

OBJECTIVES

Laryngotracheal stenosis (LTS) is a fibrotic condition of the upper airway. Recent evidence suggests dysregulated host immunity plays a role in LTS development and progression. The programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) axis, targeted by paradigm-shifting immunotherapies for cancer treatment, has also recently been implicated in the pathogenesis of fibrotic pulmonary disease. However, a role for the PD-1/PD-L1 axis in the proximal airway fibrosis seen in LTS patients has not been explored.

STUDY DESIGN

Controlled ex vivo study.

METHODS

Expression of PD-1, PD-L1, CD4, and CD8 were evaluated using immunohistochemical staining of cricotracheal resection specimens from postintubation iatrogenic laryngotracheal stenosis (iLTS), idiopathic subglottic stenosis (iSGS) patients, and normal controls derived from rapid autopsy (n = 8 per group). Fibroblasts derived from iLTS scar were also treated with transforming growth factor beta 1 (TGFβ1) and analyzed for PD-L1 expression by quantitative real-time polymerase chain reaction (n = 6).

RESULTS

iLTS specimens exhibited increased expression of PD-1, PD-L1, and CD4 (all P < .0167) compared to controls, whereas iSGS specimens exhibited increased expression of PD-1 and CD4 (P < .0167) compared to controls. PD-1, PD-L1, and CD4 showed periepithelial patterns of expression in both disease cohorts. TGFβ1 treatment of iLTS fibroblasts increased expression of PD-L1 (the cognate ligand for PD-1).

CONCLUSION

Expression of both PD-1 and its ligand PD-L1 are significantly greater in patients with iLTS compared to controls, and PD-1 expression is also elevated in patients with iSGS. Given published evidence implicating the PD-1/PD-L1 axis in pulmonary fibrosis, this suggests a possible role for checkpoint inhibitors targeting the PD-1/PD-L1 axis for the treatment of LTS.

LEVEL OF EVIDENCE

N/A Laryngoscope, 131:967-974, 2021.

Early Surgical Management of Thermal Airway Injury: A Case Series

Inhalation injury is an independent risk factor in burn mortality, imparting a 20% increased risk of death. Yet there is little information on the natural history, functional outcome, or pathophysiology of thermal injury to the laryngotracheal complex, limiting treatment progress. This paper demonstrates a case series (n = 3) of significant thermal airway injuries. In all cases, the initial injury was far exceeded by the subsequent immune response and aggressive fibroinflammatory healing. Serial examination demonstrated progressive epithelial injury, mucosal inflammation, airway remodeling, and luminal compromise. Histologic findings in the first case demonstrate an early IL-17A response in the human airway following thermal injury. This is the first report implicating IL-17A in the airway mucosal immune response to thermal injury. Their second and third patients received Azithromycin targeting IL-17A and showed clinical responses. The third patient also presented with exposed tracheal cartilage and underwent mucosal reconstitution via split-thickness skin graft over an endoluminal stent in conjunction with tracheostomy. This was associated with rapid abatement of mucosal inflammation, resolution of granulation tissue, and return of laryngeal function. Patients who present with thermal inhalation injury should receive a thorough multidisciplinary airway evaluation, including early otolaryngologic evaluation. New early endoscopic approaches (scar lysis and mucosal reconstitution with autologous grafting over an endoluminal stent), when combined with targeted medical therapy aimed at components of mucosal airway inflammation (local corticosteroids and systemic Azithromycin targeting IL-17A), may have potential to limit chronic cicatricial complications.

Laryngotracheal Mucosal Surface Expression of Candidate Biomarkers in Idiopathic Subglottic Stenosis

OBJECTIVES

Idiopathic subglottic stenosis (iSGS) is an inflammatory process leading to fibrosis and narrowing of the laryngotracheal airway. There is variability in patient response to surgical intervention, but the mechanisms underlying this variability are unknown. In this pilot study, we measure expression of candidate targets at the mucosal surface of the subglottis in iSGS patients. We aim to identify putative biomarkers for iSGS that provide insights into the molecular basis of disease progression, yield a gene signature for the disease, and/or predict a response to therapy.

STUDY DESIGN

In vitro comparative study of human cells.

METHODS

Levels of candidate transcripts and proteins were measured in healthy and stenotic laryngotracheal tissue specimens taken from the mucosal surface in 16 iSGS patients undergoing endoscopic balloon dilation. Pre- and post-operative pulmonary function test and patient reported voice and breathing outcomes were also assessed. Unsupervised clustering was used to define patient subgroups based on expression profile.

RESULTS

Pulmonary function and voice and breathing outcome metrics demonstrated significant post-operative improvement. Transcript levels of αSMA, CCL2, COL1A1, COL3A1, FN1, IFNG, and TGFB1 and protein levels of CCL2, IFNG, and IL-6 were significantly upregulated in stenotic as compared to healthy tissues. Marked heterogeneity was observed in the patterns of expression of candidate markers across individuals and tissue types. Patient subgroups defined by expression profile did not show a statistically significant difference in dilation interval.

CONCLUSION

Pro-inflammatory and pro-fibrotic pathways are significantly upregulated along the mucosal surface of stenotic laryngotracheal tissues, and CCL2 and IFNG merit further investigation as potential iSGS biomarkers.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:342-349, 2021.

An Adolescent With Progressive Shortness of Breath

Shortness of breath and wheezing are common presenting signs for children in the emergency department. In adolescence, it is often due to asthma or lower respiratory tract infections. We present a rare pediatric case of an adolescent with biphasic stridor and progressive exercise-induced shortness of breath who was found to have severe idiopathic subglottic stenosis.

Anti-fibrosis activity of quercetin attenuates rabbit tracheal stenosis via the TGF-β/AKT/mTOR signaling pathway

AIMS

This study aimed to explore the possible mechanism of trauma-induced laryngotracheal stenosis and potential protective and therapeutic efficacy of quercetin on trauma-induced laryngotracheal stenosis.

MAIN METHODS

The expression and activity of fibrotic factors [interleukin (IL)-6, IL-8, autophagy related 5 (ATG5), collagen (COL)-1, tumor growth factor (TGF)-β COL-3, microtubule-associated proteins 1A/1B light chain 3A (LC3), and vascular endothelial growth factor (VEGF)] and fibrotic signaling mediators [mammalian target of rapamycin (mTOR) and phosphorylated AKT (pAKT)] were detected by real-time quantitative PCR (qRT-PCR), ELISA, Western blot, and immunohistochemical staining, respectively, in the lipopolysaccharide (LPS)-induced WI-38 (a human embryonic lung fibroblast cell line) cellular fibrotic model and a trauma-induced rabbit tracheal stenosis model, with and without quercetin treatment.

KEY FINDINGS

Pre-treatment with quercetin significantly reversed the LPS-induced upregulation of pro-fibrotic factors (IL-6, IL-8, COL-1, COL-3, LC3) and fibrotic signaling mediators (mTOR and AKT), and it induced the downregulation of ATG5 in the WI-38 cells. Furthermore, the anti-fibrotic activity of quercetin was confirmed in the trauma-induced rabbit tracheal stenosis model. Thus, the nasogastric administration of quercetin attenuated the tracheal stenosis of the rabbit tracheal stenosis model, in addition to effectively reversing an increase in pro-fibrotic factors (VEGF, IL-6, TGF-β, COL-1, and COL-3) and fibrotic signaling mediators (mTOR and AKT), as well as downregulating ATG5 of the rabbit tracheal stenosis model.

SIGNIFICANCE

Quercetin exhibits anti-fibrotic activity by inhibiting pro-fibrotic factors and AKT/mTOR signaling pathway, in addition to activating autophagy activity. This study provided experimental evidence supporting the application of quercetin in tracheal stenosis, clinically.

The role of inflammatory cytokines in the development of idiopathic subglottic stenosis

Idiopathic subglottic stenosis (iSGS) is a debilitating extrathoracic obstruction involving the lower laryngeal and upper tracheal airway. It arises without a known antecedent injury or associated disease process. iSGS is a fibrotic disease marked histologically by excessive accumulation of fibrous connective tissue components of the extracellular matrix (ECM, i.e., collagen and fibronectin) in inflamed tissue, which leads to airway obstruction and clinical dyspnea. Diverse diseases in divergent organ systems are associated with fibrosis, suggesting common pathogenic pathways. One of the most common is sustained host inflammation. Recent investigations focusing on the inflammatory response associated with iSGS have sought to characterize the immunophenotype and cytokine profile of the airway scar in iSGS. While the role of the immune response as inciting event in iSGS remains unresolved, the centrality of an active immune response to the observed subglottic tissue remodeling is becoming more defined.

Serial In-Office Intralesional Steroid Injections in Airway Stenosis

Importance

Endoscopic dilation is the mainstay treatment strategy for subglottic and proximal tracheal stenosis (SGS/PTS). Its major limitation is restenosis requiring repeated surgery. Intralesional steroid injection (ISI) is a promising adjunctive treatment aimed at prolonging the effects of dilation.

Objective

To evaluate the association of serial in-office ISI after endoscopic dilation with surgery-free interval (SFI) in adults with SGS/PTS.

Design, Setting, and Participants

A retrospective study of adults with SGS/PTS who underwent at least 2 consecutive in-office ISI at the University of Southern California, Keck School of Medicine, over a 3-year period was conducted.

Exposure

Serial ISI with triamcinolone 40 mg/mL using topical anesthesia, spaced 3 to 6 weeks apart.

Main Outcomes and Measures

Surgery-free interval, number of dilations, need for open airway surgery, decannulation rate, and adverse events. Patients with previous dilations and sufficient follow-up time were included in a comparative analysis of SFI before and after ISI. The Mann-Whitney U test was applied for comparisons.

Results

Twenty-four patients met eligibility criteria. Mean (SD) age was 50.1 (15.1) years; 18 (75%) were female. Ten (42%) patients had idiopathic, 8 (33%) had traumatic, and 6 (25%) had rheumatologic-related SGS/PTS. Mean (SD) follow-up time was 32.3 (33.4) months. Patients underwent mean (SD) 4.08 (1.91) injections. Seventeen (71%) patients have not undergone further surgery after ISI. Mean (SD) SFI was 17.8 (12.8) months overall and was 15.7 (10.6) months for idiopathic, 13.8 (9.9) for traumatic, and 26.7 (16.9) for rheumatologic-related SGS/PTS. Twenty-one (88%) patients underwent dilation(s) prior to ISI. Among patients who fulfilled eligibility criteria for comparison of SFI before and after ISI, SFI improved from 10.1 months before, to 22.6 months after ISI (mean difference, 12.5 months; 95% CI, -2.1 to 27.2 months). Three of 6 patients (all with traumatic SGS/PTS) presenting with a tracheotomy were decannulated. No patients required open airway surgery after ISI. There were no adverse events associated with ISI.

Conclusions and Relevance

Serial in-office ISI are safe and well-tolerated in adults with SGS/PTS. This technique can reduce the surgical burden on these patients and may obviate the need for future airway intervention.

Early medical therapy for acute laryngeal injury (ALgI) following endotracheal intubation: a protocol for a prospective single-centre randomised controlled trial

INTRODUCTION

Respiratory failure requiring endotracheal intubation accounts for a significant proportion of intensive care unit (ICU) admissions. Little attention has been paid to the laryngeal consequences of endotracheal intubation. Acute laryngeal injury (ALgI) after intubation occurs at the mucosal interface of the endotracheal tube and posterior larynx and although not immediately manifest at extubation, can progress to mature fibrosis, restricted glottic mobility and clinically significant ventilatory impairment. A recent prospective observational study has shown that >50% of patients intubated >24 hours in an ICU develop ALgI. Strikingly, patients with AlgI manifest significantly worse subjective breathing at 12 weeks. Current ALgI treatments are largely surgical yet offer a marginal improvement in symptoms. In this study, we will examine the ability of a postextubation medical regime (azithromycin and inhaled budesonide) to improve breathing 12 weeks after ALgI. METHODS AND ANALYSIS: A prospective, single-centre, double-blinded, randomised, control trial will be conducted at Vanderbilt Medical Center. Participants will be recruited from adult patients in ICUs. Participants will undergo a bedside flexible nasolaryngoscopy for the identification of ALgI within 72 hours postextubation. In addition, participants will be asked to complete peak expiratory flow measurements immediately postintubation. Patients found to have ALgI will be randomised to the placebo control or medical therapy group (azithromycin 250 mg and budesonide 0.5 mg for 14 days). Repeat peak expiratory flow, examination of the larynx and patient-reported Clinical COPD (chronic obstructive pulmonary disease) Questionnaire, Voice Handicap Index and 12-Item Short Form Health Survey questionnaires will be conducted at 12 weeks postextubation. Consented patients will also have patient-specific, disease-specific and procedure-specific covariates abstracted from their medical record.

ETHICS AND DISSEMINATION

The Institutional Review Board (IRB) Committee of the Vanderbilt University Medical Center has approved this protocol (IRB #171066). The findings of the trial will be disseminated through peer-reviewed journals, national and international conferences.

TRIAL REGISTRATION NUMBER

NCT03250975.

Laryngotracheal Microbiota in Adult Laryngotracheal Stenosis

Laryngotracheal stenosis is an obstructive respiratory disease that leads to voicing difficulties and dyspnea with potential life-threatening consequences. The majority of incidences are due to iatrogenic etiology from endotracheal tube intubation; however, airway scarring also has idiopathic causes. While recent evidence suggests a microbial contribution to mucosal inflammation, the microbiota associated with different types of stenosis has not been characterized. High-throughput sequencing of the V4 region of the16S rRNA gene was performed to characterize the microbial communities of 61 swab samples from 17 iatrogenic and 10 adult idiopathic stenosis patients. Nonscar swabs from stenosis patients were internal controls, and eight swabs from four patients without stenosis represented external controls. Significant differences in diversity were observed between scar and nonscar samples and among sample sites, with decreased diversity detected in scar samples and the glottis region. Permutational analysis of variance (PERMANOVA) results revealed significant differences in community composition for scar versus nonscar samples, etiology type, sample site, groups (iatrogenic, idiopathic, and internal and external controls), and individual patients. Pairwise Spearman's correlation revealed a strong inverse correlation between Prevotella and Streptococcus among all samples. Finally, bacteria in the family Moraxellaceae were found to be distinctly associated with idiopathic stenosis samples in comparison with external controls. Our findings suggest that specific microbiota and community shifts are present with laryngotracheal stenosis in adults, with members of the family Moraxellaceae, including the known pathogens Moraxella and Acinetobacter, identified in idiopathic scar. Further work is warranted to elucidate the contributing role of bacteria on the pathogenesis of laryngotracheal stenosis.IMPORTANCE The laryngotracheal region resides at the intersection between the heavily studied nasal cavity and lungs; however, examination of the microbiome in chronic inflammatory conditions of the subglottis and trachea remains scarce. To date, studies have focused on the microbiota of the vocal folds, or the glottis, for laryngeal carcinoma, as well as healthy larynges, benign vocal fold lesions, and larynges exposed to smoking and refluxate. In this study, we seek to examine the structure and composition of the microbial community in adult laryngotracheal stenosis of various etiologies. Due to the heterogeneity among the underlying pathogenesis mechanisms and clinical outcomes seen in laryngotracheal stenosis disease, we hypothesized that different microbial profiles will be detected among various stenosis etiology types. Understanding differences in the microbiota for subglottic stenosis subtypes may shed light upon etiology-specific biomarker identification and offer novel insights into management approaches for this debilitating disease.

Vocal function exercises for normal voice: With and without semi-occlusion

PURPOSE

This study examined the effect of varying degrees of vocal tract (VT) occlusion used during Vocal Function Exercises (VFEs) on attainment of maximum phonation time (MPT) goals in normal voice. Greater VT occlusion was expected to result in increased MPT. The overarching goal was to determine whether the semi-occluded vocal tract (SOVT) posture used during VFEs could be modified while preserving efficacy.

METHOD

Twenty-six females ages 18-30 participated in this pre-post longitudinal group study. Participants were randomly assigned to three experimental groups and completed a six-week VFE protocol. The first group performed exercises using the prescribed SOVT posture; the second group used the vowel /o/; group three used the vowel /a/. The primary outcome measure was MPT as performed on the exercise tasks using the assigned vocal tract posture.

RESULT

MPT significantly improved in the prescribed SOVT group, but did not significantly improve in the modified /o/ and /a/ groups.

CONCLUSION

The SOVT posture used during VFEs is modifiable to a small extent without significantly undermining efficacy. Changes in MPT are less robust with reduced VT occlusion. Research in a clinical population is warranted.

T-Helper 2 Lymphocyte Immunophenotype Is Associated With Iatrogenic Laryngotracheal Stenosis

OBJECTIVE/HYPOTHESIS

This prospective controlled human and murine study assessed the presence of inflammatory cells and cytokines to test the hypothesis that immune cells are associated with fibroproliferation in iatrogenic laryngotracheal stenosis (iLTS).

METHODS

Inflammation was assessed by histology and immunofluorescence (IF), quantitative real-time polymerase chain reaction (qRT-PCR), and flow cytometry of cricotracheal resections of iLTS patients compared to normal controls. An iLTS murine model assessed the temporal relationship between inflammation and fibrosis.

RESULTS

iLTS specimens showed increased inflammation versus normal controls (159/high power field [hpf] vs. 119/hpf, P = 0.038), and increased CD3 + T-cells, CD4 + cells, and CD3+/CD4 + T-helper (T_H ) cells (all P < 0.05). The inflammatory infiltrate was located immediately adjacent to the epithelial surface in the superficial aspect of the thickened lamina propria. Human flow cytometry and qRT-PCR showed a significant increase in interleukin (IL)-4 gene expression, indicating a T_H 2 phenotype. Murine IF revealed a dense CD4 + T-cell inflammatory infiltrate on day 4 to 7 postinjury, which preceded the development of fibrosis. Murine flow cytometry and qRT-PCR studies mirrored the human ones, with increased T-helper cells and IL-4 in iLTS versus normal controls.

CONCLUSION

CD3/CD4 + T-helper lymphocytes and the proinflammatory cytokine IL-4 are associated with iLTS. The association of a T_H 2 immunophenotype with iLTS is consistent with findings in other fibroinflammatory disorders. The murine results reveal that the inflammatory infiltrate precedes the development of fibrosis. However, human iLTS specimens with well-developed fibrosis also contain a marked chronic inflammatory infiltrate, suggesting that the continued release of IL-4 by T-helper lymphocytes may continue to propagate iLTS.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:177-186, 2019.

Pathologic Fibroblasts in Idiopathic Subglottic Stenosis Amplify Local Inflammatory Signals

OBJECTIVE

To characterize the phenotype and function of fibroblasts derived from airway scar in idiopathic subglottic stenosis (iSGS) and to explore scar fibroblast response to interleukin 17A (IL-17A).

STUDY DESIGN

Basic science.

SETTING

Laboratory.

SUBJECTS AND METHODS

Primary fibroblast cell lines from iSGS subjects, idiopathic pulmonary fibrosis subjects, and normal control airways were utilized for analysis. Protein, molecular, and flow cytometric techniques were applied in vitro to assess the phenotype and functional response of disease fibroblasts to IL-17A.

RESULTS

Mechanistically, IL-17A drives iSGS scar fibroblast proliferation ( P < .01), synergizes with transforming growth factor ß1 to promote extracellular matrix production (collagen and fibronectin; P = .04), and directly stimulates scar fibroblasts to produce chemokines (chemokine ligand 2) and cytokines (IL-6 and granulocyte-macrophage colony-stimulating factor) critical to the recruitment and differentiation of myeloid cells ( P < .01). Glucocorticoids abrogated IL-17A-dependent iSGS scar fibroblast production of granulocyte-macrophage colony-stimulating factor ( P = .02).

CONCLUSION

IL-17A directly drives iSGS scar fibroblast proliferation, synergizes with transforming growth factor ß1 to promote extracellular matrix production, and amplifies local inflammatory signaling. Glucocorticoids appear to partially abrogate fibroblast-dependent inflammatory signaling. These results offer mechanistic support for future translational study of clinical reagents for manipulation of the IL-17A pathway in iSGS patients.