Degrees of Inflammation in the Treatment of Subglottic Stenosis in a Rabbit Model: Histopathological Assessment of a Novel Bioabsorbable Ultra-high Ductility Magnesium Alloy Stent.

OBJECTIVE: Utilizing a novel histopathological scoring system and subglottic stenosis (SGS) rabbit model, we aimed to compare degrees of inflammation and severity of narrowing in the subglottis between two minimally invasive therapeutic modalities: endoscopic balloon dilation (EBD) alone versus EBD with placement of a bioabsorbable ultra-high ductility magnesium (UHD-Mg) alloy stent. METHODS: SGS was induced endoscopically via microsuspension laryngoscopy in 23 New Zealand white rabbits. The control group (n = 11) underwent EBD alone, the study arm (n = 12) underwent EBD with implantation of bioabsorbable UHD-Mg alloy stents. Rabbits were euthanized at 2-, 3-, and 6-weeks after SGS induction, coinciding with wound healing stages. Using Optical Coherence Tomography (OCT), cross-sectional areas of airways were compared to calculate the mean percentage of intraluminal area at sequential time points. A novel histopathological scoring system was used to analyze frozen sections of laryngotracheal complexes. The degree of inflammation was quantified by scoring changes in inflammatory cell infiltration, epithelial ulceration/metaplasia, subepithelial edema/fibrosis, and capillary number/dilation. Univariate analysis was utilized to analyze these markers. RESULTS: We found rabbits implanted with the bioabsorbable UHD-Mg alloy stent had statistically significantly higher scores in categories of hyperplastic change (stents vs controls: 1.48 vs 0.46 p < 0.001), squamous metaplasia (22 vs 5 p < 0.001), and neutrophils/fibrin in lumen (31 vs 8, p < 0.001). Rabbits who received EBD alone had higher scores of subepithelial edema and fibrosis (2.70 vs 3.49, p < 0.0256). The stented rabbits demonstrated significantly increased mean percent stenosis by intraluminal mean area compared to controls at 2 weeks (88.56 vs 58.98, p = 0.032), however at all other time points there was no significant difference between intraluminal subglottic stenosis by mean percent stenosis area. DISCUSSION: Rabbits with SGS treated with UHD-Mg alloy stents demonstrated histopathologic findings suggestive of lower levels of tracheal fibrosis. This could indicate a reduced tendency towards the development of stenosis when compared to EBD alone. There was not a difference in luminal size between stent and non-stented rabbits at the six-week end point. Histologically, however, overall the use of bioabsorbable UHD-Mg alloy stenting elicited a greater tissue response at the level of the superficial mucosa rather than fibrosis of the lamina propria seen in the stented rabbits. This suggests more favorable healing and less of a tendency towards fibrosis and stenosis even though there may not be a benefit from a luminal size standpoint during this early healing period. Compared to known complications of currently available non-bioabsorbable metal or silicone-based stents, this proof-of-concept investigation highlights the potential use of a novel biodegradable UHD-Mg stent as a therapeutic modality for pediatric SGS.

POSTN Regulates Fibroblast Proliferation and Migration in Laryngotracheal Stenosis Through the TGF-ß/RHOA Pathway.

OBJECTIVES: To investigate the role of periostin (POSTN) and the transforming growth factor ß (TGF-ß) pathway in the formation of laryngotracheal stenosis (LTS) scar fibrosis and to explore the specific signaling mechanism of POSTN-regulated TGF-ß pathway in tracheal fibroblasts. METHODS: Bioinformatics analysis was performed on scar data sets from the GEO database to preliminarily analyze the involvement of POSTN and TGF-ß pathways in fibrosis diseases. Expression of POSTN and TGF-ß pathway-related molecules was analyzed in LTS scar tissue at the mRNA and protein levels. The effect of POSTN on the biological behavior of tracheal fibroblasts was studied using plasmid DNA overexpression and siRNA silencing techniques to regulate POSTN expression and observe the activation of TGF-ß1 and the regulation of cell proliferation and migration via the TGF-ß/RHOA pathway. RESULTS: The bioinformatics analysis revealed that POSTN and the TGF-ß pathway are significantly involved in fibrosis diseases. High expression of POSTN and TGF-ß/RHOA pathway-related molecules (TGFß1, RHOA, CTGF, and COL1) was observed in LTS tissue at both mRNA and protein levels. In tracheal fibroblasts, overexpression or silencing of POSTN led to the activation of TGF-ß1 and regulation of cell proliferation and migration through the TGF-ß/RHOA pathway. CONCLUSION: POSTN is a key molecule in scar formation in LTS, and it regulates the TGF-ß/RHOA pathway to mediate the formation of cicatricial LTS by acting on TGF-ß1. This study provides insights into the molecular mechanisms underlying LTS and suggests potential therapeutic targets for the treatment of this condition. LEVEL OF EVIDENCE: NA Laryngoscope, 134:4078-4087, 2024.

[Idiopathic Subglottic Tracheal Stenosis]. / Idiopathische subglottische Tracheastenose.

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.

Association between Estrogen Exposure and Idiopathic Subglottic Stenosis.

OBJECTIVE: Idiopathic subglottic stenosis (iSGS) is a rare, recurrent, fibroinflammatory disease affecting the larynx and proximal trachea. Given it occurs primarily in adult females, estrogen is speculated to play a central pathophysiological role. This study aimed to evaluate relationships between estrogen exposure, disease progression, and recurrence. METHODS: North American Airway Collaborative (NoAAC) data of adults with iSGS obstructive airway lesions, who underwent index endoscopic airway dilation, were used to identify associations between estrogen exposure, disease characteristics, and time to recurrence (TTR), and interventions were analyzed using Kruskal-Wallis test and Pearson coefficient. Cox proportional hazards regression models compared hazard ratios by estrogen exposure. Kaplan-Meier curves were plotted for TTR based on menopausal status. RESULTS: In all, 533 females had complete estrogen data (33% premenopausal, 17% perimenopausal, 50% postmenopausal). Median estrogen exposure was 28 years. Overall, there was no dose-response relationship between estrogen exposure and disease recurrence. Premenopausal patients had significantly shorter time from symptom manifestation to diagnosis (1.17 vs. 1.42 years perimenopausal vs. 2.08 years postmenopausal, p < 0.001), shorter time from diagnosis to index endoscopic airway dilation (1.90 vs. 2.50 vs. 3.76 years, p = 0.005), and higher number of procedures (1.73 vs. 1.20 vs. 1.08 procedures, p < 0.001). CONCLUSIONS: We demonstrate premenopausal patients may have a more aggressive disease variant than their peri- and postmenopausal counterparts. However, it is unclear as to whether this is related to reduced estrogen in the peri- and postmenopausal states or the age-related physiology of wound healing and inflammation, regardless of estrogen. LEVEL OF EVIDENCE: 3 Laryngoscope, 134:825-830, 2024.

Utilizing a Functional Lumen Imaging Probe for Evaluation of the Pediatric Airway, A Pilot Study.

OBJECTIVES: Accurate and reproducible measurements of the pediatric airway are critical for diagnostic evaluation and management of subglottic and tracheal stenosis. The endoluminal functional lumen imaging probe (EndoFLIP) is a catheter-based imaging probe which utilizes impedance planimetry to calculate luminal parameters, including cross-sectional area and compliance. Herein, we demonstrate the feasibility of this system for multidimensional evaluation of the pediatric airway. METHODS: 3D-printed pediatric laryngotracheal models were created based on computed tomography scans, then artificially deformed to simulate both circumferential and posterior subglottic stenosis. Two observers made six measurements of the minimum cross-sectional area (MCSA) and length of stenosis of each model with EndoFLIP. Agreement between observer measurements and model dimensions was evaluated using Lin's concordance correlation coefficient; inter-observer reliability was assessed using intraclass correlation. RESULTS: Four models were created: two without pathology (MCSA: 132.4, 44.3 mm2 ) and two with subglottic stenosis (MCSA: 28.7, 59.7 mm2 , stenotic length 27.8, 24.4 mm). Observer measurements of MCSA and length of stenosis demonstrated high concordance with the models (r = 0.99, 0.95, p < 0.001) with a mean error of 4.5% and 18.2% respectively. There was a low coefficient of variation (0.6%-2.8%) for measurements, indicating high precision. Interrater reliability was high for both MCSA and stenotic length (ICC: 0.99, 0.98). CONCLUSIONS: The EndoFLIP system allows for accurate and reproducible measurements of cross-sectional area and stenotic length in pediatric airway models. This method may provide further advantages in the evaluation of airway distensibility, as well as measurements of asymmetric airway pathology. LEVEL OF EVIDENCE: NA Laryngoscope, 134:108-112, 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.

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.

Surgical treatment of laryngeal amyloidosis: a systematic review.

PURPOSE: The aim of this review was to study the surgical management of laryngeal amyloidosis and estimate the rate of recurrence after surgery. METHODS: A systematic review searching PubMed and EMBASE was performed. A qualitative synthesis of data regarding the surgical management of LA and a quantitative analysis of the recurrence rate after surgery was conducted. RESULTS: This systematic review included 14 retrospective studies, one of whom is retrospective controlled. A total of 515 subjects were included, the mean age ranged from 43.3 to 58 years with a male-to-female ratio of 1:1.3. All cases had a localized laryngeal amyloidosis. The supraglottic region was the most affected laryngeal site and multiple sites were commonly involved. Surgical treatment consists of endoscopic excision using laser, cold or powered instruments. Open surgery is required for severe primary case or revision surgery. Surgical complications such as granulomatosis scar tissue formation, tracheostomy, laryngotracheal stenosis, pneumothorax and concomitant malignancy were developed in 17.5% of patients. The time onset to diagnosis varied from 1 months to 15 years and the duration of follow-up from 3 months to 25 years. The rate of recurrence was 28.4% (95% CI 24.5-32.6) and the timing of recurrences ranged from 3 months to 10 years. CONCLUSION: The recurrence rate after primary surgery for laryngeal amyloidosis is high. A tailored surgical treatment based on the disease extension and a long-term follow up are recommended.

Characterizing the Macrophage Population in Patients With Idiopathic Subglottic Stenosis.

OBJECTIVES: Idiopathic subglottic stenosis (iSGS) is characterized by progressive fibrosis and subglottic luminal narrowing. Currently, immune characterization has focused on T-cells; however, macrophages remain largely unexplored. The goals of this study are to characterize the transcriptome of iSGS macrophages and the fibrogenic nature of identifed biomarkers. STUDY DESIGN: Bioinformatics and in vitro. METHODS: Human tracheal biopsies from iSGS scar (n = 4), and matched non-scar (n = 4) regions were analyzed using single-cell RNA-seq (scRNA-seq). Immunofluorescence (IF) was performed on rapidly processed autopsies (RPA) and iSGS tracheal resections (n = 4) to co-localize S100A8/9 and CD11b. Collagen gene/protein expression was assessed in iSGS fibroblasts (n = 4) treated with protein S100A8/9 (1000 ng/ml). Macrophages were subclustered to identify distinct subpopulations. RESULTS: scRNA-seq analysis revealed S100A8/S100A9 (fold change (FC) = 4.1/1.88, p < 0.001) as top differentially expressed genes in iSGS macrophages. IF exhibited increased CD11b+/S100A8/9+ cells in tracheal samples of iSGS versus RPA (26.75% ± 7.08 vs. 0.594% ± 0.974, n = 4, p = 0.029). iSGS fibroblasts treated with S100A8/9 demonstrated increased gene expression of COL1A1 (FC = 2.30 ± 0.45, p = 0.03, n = 4) and COL3A1 (FC = 2.44 ± 0.40, p = 0.03, n = 4). COL1A1 protein assays revealed an increase in the experimental group, albeit not significant, (p = 0.12, n = 4). Finally, macrophage sub clustering revealed one subpopulation as a predominant source of S100A8/S100A9 expression (FC = 7.94/5.47, p < 0.001). CONCLUSIONS: S100A8/9 is a key biomarker in iSGS macrophages. Although S100A8/9 demonstrates profibrotic nature in vitro, the role of S100A8/9+ macrophages in vivo warrants further investigation. LEVEL OF EVIDENCE: NA Laryngoscope, 133:2308-2316, 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.

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.

Establishing an Endoscopic Chronic Subglottic Stenosis Rabbit Model.

OBJECTIVES/HYPOTHESIS: To develop a reproducible and consistent chronic subglottic stenosis (SGS) in an endoscopic animal model. STUDY DESIGN: Prospective study. METHODS: We conducted a prospective study using New Zealand white rabbits. Chronic SGS was induced endoscopically by Bugbee electrocautery to 50% to 75% of the subglottic area's circumference, followed by 4-hour endotracheal intubation. The rabbit airways were endoscopically assessed and sized with uncuffed endotracheal tubes (ETTs) before the injury, during follow-up, and at the endpoints. There were four endpoints: 2, 4, 6, and 8 weeks post SGS induction. Animals were humanely euthanized for histopathological examination of the subglottic injury site and microscopic measurement of the cricoid lumen. RESULTS: Twenty-two rabbits reached the endpoints, and 18 rabbits developed chronic SGS. ETT size significantly decreased by 0.5 from preinjury to the endpoint in all groups, P < .001. Control median cricoid lumen measurements were 20.48 mm2 , the median cricoid lumen measurement for the 2 weeks endpoint was 14.3 mm2 , 4 weeks 11.69 mm2 , 6 weeks 16.03 mm2 , and 8 weeks endpoint median was 16.33 mm2 . Histopathological examination showed chronic scar tissue and new cartilage formation at the cricoid level, mainly at the posterior subglottic injury site starting from 4 weeks postinjury. Collagen staining revealed substantial amounts of organized collagen and different collagen orientation starting 4 weeks postinjury lasting until 8 weeks postinjury. CONCLUSION: We developed an animal model to study chronic SGS. This model will be utilized to compare different endoscopic treatment interventions in acute SGS versus chronic SGS and further define the molecular basis of SGS. LEVEL OF EVIDENCE: NA Laryngoscope, 132:1909-1915, 2022.

Identifying Phenotypically Distinct Fibroblast Subsets in Type 2 Diabetes-Associated Iatrogenic Laryngotracheal Stenosis.

OBJECTIVE: Iatrogenic laryngotracheal stenosis (iLTS) is the pathologic narrowing of the glottis, subglottis, and/or trachea secondary to intubation or tracheostomy related injury. Patients with type 2 diabetes mellitus (T2DM) are more likely to develop iLTS. To date, the metabolomics and phenotypic expression of cell markers in fibroblasts derived from patients with T2DM and iLTS are largely unknown. STUDY DESIGN: Controlled in vitro cohort study. SETTING: Tertiary referral center (2017-2020). METHODS: This in vitro study assessed samples from 6 patients with iLTS who underwent surgery at a single institution. Fibroblasts were isolated from biopsy specimens of laryngotracheal scar and normal-appearing trachea and compared with controls obtained from the trachea of rapid autopsy specimens. Patients with iLTS were subcategorized into those with and without T2DM. Metabolic substrates were identified by mass spectrometry, and cell protein expression was measured by flow cytometry. RESULTS: T2DM iLTS-scar fibroblasts had a metabolically distinct profile and clustered tightly on a Pearson correlation heat map as compared with non-T2DM iLTS-scar fibroblasts. Levels of itaconate were elevated in T2DM iLTS-scar fibroblasts. Flow cytometry demonstrated that T2DM iLTS-scar fibroblasts were associated with higher CD90 expression (Thy-1; mean, 95%) when compared with non-T2DM iLTS-scar (mean, 83.6%; P = .0109) or normal tracheal fibroblasts (mean, 81.1%; P = .0042). CONCLUSIONS: Scar-derived fibroblasts from patients with T2DM and iLTS have a metabolically distinct profile. These fibroblasts are characterized by an increase in itaconate, a metabolite related to immune-induced scar remodeling, and can be identified by elevated expression of CD90 (Thy-1) in vitro.

Correlations of Radiographic and Endoscopic Observations in Subglottic Stenosis.

OBJECTIVE(S): Subglottic stenosis (SGS) represents a constellation of diverse pathologic processes that ultimately lead to narrowing of the subglottic region and can produce significant morbidity. Existing endoscopic and radiographic assessments may not be consistent in practice. METHODS: Severity of stenosis was evaluated and reported using the Cotton-Myer classification system from 33 endoscopic procedures from 32 unique subjects. Radiographic imaging within the preceding 3 month period was subsequently reviewed and narrowing was measured by a blinded radiologist. Degree of stenosis was reported as a percentage in 30 out of 33 endoscopic evaluations and subsequently compared to radiographically determined percentage of stenosis. Statistical analyzes were conducted to evaluate concordance between endoscopic and radiographic assessments. RESULTS: About 45.5% (15/33) of the evaluations were in agreement using Cotton-Myer scoring, while 27.3% (9/33) were discrepant by 1 grade and 27.3% (9/33) by 2 grades. Correlation of degree of stenosis as a percentage using Spearman (coefficient: 0.233, P-value: .214) and Pearson (coefficient: 0.138, P-value: .466) methods demonstrated very weak relationships. Radiographic scoring did not predict endoscopic classification to a significant degree using mixed effects regression. CONCLUSIONS: Radiographic and endoscopic grading of subglottic stenosis may not be reliably concordant in practice.

Hybrid Knife, a Novel Drug Delivery Tool for Treatment of Tracheal Stenosis: A Case Report.

The treatment of subglottic stenosis remains a challenge due to anatomic and technological limitations, and there is no consensus regarding treatment. Restenosis and granulation formation are the most common complications. Balloon dilatation combined with cryotherapy and adjuvant topical medication is one treatment method. However, the efficacy of adjuvant topical medication is controversial, and the lack of efficacy may be related to the effective dose of the drug delivered to the submucosal layer of the lesion. Therefore, a tool with high efficiency for delivering medications to the submucosal layer via injection may play an important role in treatment. A hybrid knife (HK) with a pressure water jet traditionally used in endoscopy submucosal dissection to inject saline into the submucosa was employed here to inject medications for subglottic stenosis, followed by electrical excision. Here, we report the case of a man with complex subglottic stenosis who underwent balloon dilatation combined with cryotherapy and an adjuvant submucosal triamcinolone injection performed with an HK. The drug was delivered more efficiently into the submucosal layer, and the lumen of the trachea was patent. Performing a submucosal injection with an HK may be a new approach to deliver medications to the submucosal layer for the treatment of tracheal stenosis.

Multi-disciplinary management of patients with benign airway strictures: A review.

Histologically benign airway strictures are frequently misdiagnosed as asthma or COPD and may present with severe symptoms including respiratory failure. A clear understanding of pathophysiology and existing classification systems is needed to determine the appropriate treatment options and predict clinical course. Clinically significant airway strictures can involve the upper and central airways extending from the subglottis to the lobar airways. Optimal evaluation includes a proper history and physical examination, neck and chest computed tomography, pulmonary function testing, endoscopy and serology. Available treatments include medical therapy, endoscopic procedures and open surgery which are based on the stricture's extent, location, etiology, morphology, severity of airway narrowing and patient's functional status. The acuity of the process, patient's co-morbidities and operability at the time of evaluation determine the need for open surgical or endoscopic interventions. The optimal management of patients with benign airway strictures requires the availability, expertise and collaboration of otolaryngologists, thoracic surgeons and interventional pulmonologists. Multidisciplinary airway teams can facilitate accurate diagnosis, guide management and avoid unnecessary procedures that could potentially worsen the extent of the disease or clinical course. Implementation of a complex airway program including multidisciplinary clinics and conferences ensures that such collaboration leads to timely, patient-centered and evidence-based interventions. In this article we outline algorithms of care and illustrate therapeutic techniques based on published evidence.

Down-Regulation of a Profibrotic Transforming Growth Factor-ß1/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)-ß1 was up-regulated primarily in glandular epithelium. Cellular communication network factor 2 (CCN2) was mainly up-regulated in stromal fibroblasts surrounding TGF-ß1-positive glandular structures. SILSI improved iSGS by reducing fibroblast infiltration and increasing matrix remodeling. Mechanistically, SILSI counteracted the effects of TGF-ß1 by inducing matrix metalloprotease 9 (MMP9) expression while repressing CCN2 expression, without affecting TGFß1 levels. Treatment of primary iSGS-derived fibroblasts with TGF-ß1 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-ß1. 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-ß1/CCN2/MMP9 axis involved in iSGS development.

The heterogeneity of fibroblasts in laryngotracheal stenosis and skin hypertrophic scar in pediatric patients.

OBJECTIVES: To investigate the heterogeneity between the laryngotracheal stenosis and hypertrophic scar derived fibroblasts. METHODS: Human laryngotracheal stenosis (LTS) and skin hypertrophic scar (HTS) specimens were obtained during the tracheal resection and T-shaped tracheal stent implantation surgery. Fibroblasts were isolated and cultured. Cell proliferation and migration were analyzed by cell count, EdU proliferation and wound-healing assays. The expressions of COL1a1, α-SMA, TGF-ß1 signaling pathway, chemokines and receptors were analyzed by qRT-PCR, western blotting, and immunohistochemistry. RESULTS: Cell proliferation and migration of LTS derived fibroblasts were significantly faster than HTS fibroblasts, with no significant difference of the percentage of apoptotic cells. COL1a1, α-SMA, and Integrins were down-regulated in LTS fibroblasts, but TGFB1 and chemokine receptor CXCR7 were up-regulated in LTS fibroblasts. However, the expressions of SMAD4 and phospho-SMAD2/3 were not significantly different. CONCLUSIONS: Human LTS and HTS derived fibroblasts differ in cell proliferation and migration. Different expressions of COL1a1, α-SMA, and CXCR7 were found between the two fibroblasts.