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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, 134:4239-4245, 2024., (© 2024 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives: To investigate the role of periostin (POSTN) and the transforming growth factor β (TGF-β) pathway in the formation of laryngotracheal stenosis (LTS) scar fibrosis and to explore the specific signaling mechanism of POSTN-regulated TGF-β 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-β pathways in fibrosis diseases. Expression of POSTN and TGF-β 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-β1 and the regulation of cell proliferation and migration via the TGF-β/RHOA pathway., Results: The bioinformatics analysis revealed that POSTN and the TGF-β pathway are significantly involved in fibrosis diseases. High expression of POSTN and TGF-β/RHOA pathway-related molecules (TGFβ1, 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-β1 and regulation of cell proliferation and migration through the TGF-β/RHOA pathway., Conclusion: POSTN is a key molecule in scar formation in LTS, and it regulates the TGF-β/RHOA pathway to mediate the formation of cicatricial LTS by acting on TGF-β1. 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., (© 2024 The American Laryngological, Rhinological and Otological Society, Inc.)

Studies have highlighted an upregulation of PD-1 expression in CD4 + T cells, which accelerates lung fibrosis by activating the IL-17/STAT3 pathway, leading to IL-17A and TGF-β1 secretion. However, the relation with traumatic tracheal stenosis (TS) remains unexplored. Our analysis found significant increases in PD-1 + CD4 + T cells, IL-17A, and TGF-β1 in the TS patients (n = 10). The cellular model used CD4 + T cells co-cultured with bronchial fibroblasts while the animal model used a nylon brush to scrape the damaged tracheal mucosa. Interventions with PD-1 and STAT3 inhibitors both in vitro (n = 5) and in vivo (n = 6) showed decreased expression of TGF-β1 and IL-17A in CD4 + T cells, decreased collagen I synthesis in vitro, and reduced tractal fibrosis in vivo. Furthermore, PD-1's modulation of the STAT3 was evident. This research unveils PD-1 + CD4 + T cells' role in TS, thus suggesting a novel immunotherapeutic strategy to counteract tracheal fibrosis., Competing Interests: Declaration of competing interest All authors disclosed no relevant relationship., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Background: Tracheal transplantation has been considered the ideal option for the reconstruction of long-segment circumferential tracheal defects. Our group developed a technique for vascularized single-staged tracheal transplantation. Twenty months ago, we performed the first-in-human tracheal transplantation. Herein, we report a twenty-month follow-up., Methods: The recipient presented with a 9.0 cm airway tracheal stenosis and complete cricoid stenosis. The patient previously failed six major conventional surgical procedures. Prior to transplantation, the patient's airway was maintained with an extended tracheostomy and stent. The patient experienced repeated life-threatening airway obstruction because of mucous plugging and obstructive granulation tissue. In January 2020 the patient underwent a single-staged tracheal transplantation treated with triple-therapy immunosuppression. Organ rejection was monitored with endoscopic tracheoscopy, narrow-band imaging, free-cell DNA assessment, and histological and cytogenetic analysis of tracheal biopsies. Mucociliary function was assessed with dye motility studies., Results: Twenty months following transplantation, there has been no evidence of acute or chronic rejection. Since day 60, there has been no detectable free cell DNA, a surrogate marker for immune-mediated allograft rejection. Fluorescence in situ hybridization (FISH) cytogenetics demonstrated that the donor trachea was repopulated with recipient epithelium establishing a chimeric allograft. Narrow-band imaging demonstrates a well-vascularized epithelial mucosa and bronchoscopic biopsies demonstrate normal ciliated epithelial architecture and viable epithelial lining with functional ciliated epithelium. The patient has resumed a normal life without a stent or tracheostomy and has returned to work., Conclusions: Twenty months after single-staged vascularized tracheal transplantation, the trachea is functional and the patient breathes without the need for a tracheostomy or stent. Single-staged long-segment tracheal transplantation is a viable option for tracheal defects that are not amenable to conventional reconstructive techniques., Level of Evidence: 4 Laryngoscope, 133:1839-1845, 2023., (© 2022 The American Laryngological, Rhinological and Otological Society, Inc.)

To investigate the role of tracheal wall injury in the development of benign airway stenosis in rabbits. Prospective study. We injured the tracheal walls of 28 New Zealand white rabbits using four different methods. Experimental group: Group A (n = 7, mild injury of tracheal mucosa by ordinary brush under bronchoscopy); Group B (n = 7, severe injury of tracheal mucosa by nylon brush under tracheotomy); Group C (n = 7, tracheal cartilage was injured by vascular clamp after tracheotomy); Group D (n = 7, the tracheal cartilage was injured with vascular forceps and the tracheal mucosa was injured with a nylon brush after tracheotomy). Bronchoscopy was performed on each experimental rabbit at 1, 2, 3 and 4 weeks after operation. High-resolution computed tomography (HRCT) and endobronchial optical coherence tomography (EB-OCT) were performed at 4 weeks, and the rabbits were sacrificed after the examination. Their gross and histological findings were comparatively determined whether the experimental rabbit stenosis was established. No airway stenosis was observed in group A. In group B, 28.57% of experimental rabbits developed tracheal stenosis (granulation tissue proliferation was observed in rabbits No. 2 and No. 6 at 1, 2 and 3 weeks after operation, and the tracheal scar contracture was observed in No.6 rabbit at 4 weeks after operation). Fourteen rabbits in group C and group D had tracheal stenosis caused by granulation tissue proliferation at 1, 2 and 3 weeks after operation. At the fourth week after operation, 71.43% of experimental rabbits had tracheal stenosis due to granulation tissue hyperplasia, 7.14% of experimental rabbits had tracheal stenosis due to scar contracture and granulation hyperplasia, and 21.43% of experimental rabbits had tracheal stenosis due to scar contracture. EB-OCT scan showed that the cartilage layer with low signal reflection band was discontinuous. The injury of cartilage is the key factor of benign airway stenosis. Acute injury of airway mucosa alone is unlikely to cause airway stenosis, but combined with cartilage injury may aggravate airway stenosis. EB-OCT can clearly identify the airway layers of rabbits, which is helpful to evaluate the damage of tracheal cartilage and mucosa. The diagnostic potential of this technique makes EB-OCT a promising approach for the study and monitoring of airway diseases., (© 2023. The Author(s).)

Benign tracheobronchial stenosis (BTS) is a fatal and incurable disease. Epithelial repair and matrix reconstruction play an important role in the wound repair process. If the interstitial context is not restored and stabilized in time, it can lead to pathological fibrosis. Here we attempted to identify cytokines that are involved in promoting wound repair. Growth differentiation factor 15 (GDF15) is a cytokine secreted by tracheal epithelial cells, which is indispensable for the growth of epithelial cells and inhibits the overgrowth of fibroblasts. GDF15 can counteract transforming growth factor-β (TGFβ1) stimulation of epithelial-mesenchymal transition (EMT) in tracheal epithelial cells and inhibit fibroblast activation via the TGFβ1-SMAD2/3 pathway. In a rat model of tracheal stenosis, GDF15 supplementation alleviated the degree of tracheal stenosis. These results suggest that GDF15 prevents fibroblast hyperactivation and promotes epithelial repair in injured trachea. GDF15 may be a potential therapy to improve benign tracheobronchial stenosis., Competing Interests: Declaration of competing interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022. Published by Elsevier Inc.)

Objective: Characterize and quantify epithelium in multiple etiologies of laryngotracheal stenosis (LTS) to better understand its role in pathogenesis., Study Design: Controlled in vitro cohort study., Methods: Endoscopic brush biopsy samples of both normal (non-scar) and scar were obtained in four patients with idiopathic subglottic stenosis (iSGS) and four patients with iatrogenic LTS (iLTS). mRNA expression of basal, ciliary, and secretory cell markers were evaluated using quantitative PCR. Cricotracheal resection tissue samples (n = 5 per group) were also collected, analyzed using quantitative immunohistochemistry, and compared with rapid autopsy tracheal samples., Results: Both iSGS and iLTS-scar epithelium had reduced epithelial thickness compared with non-scar control epithelium (P = .0009 and P = .0011, respectively). Basal cell gene and protein expression for cytokeratin 14 was increased in iSGS-scar epithelium compared with iLTS or controls. Immunohistochemical expression of ciliary tubulin alpha 1, but not gene expression, was reduced in both iSGS and iLTS-scar epithelium compared with controls (P = .0184 and P = .0125, respectively). Both iSGS and iLTS-scar had reductions in Mucin 5AC gene expression (P = .0007 and P = .0035, respectively), an epithelial goblet cell marker, with reductions in secretory cells histologically (P < .0001)., Conclusions: Compared with non-scar epithelium, the epithelium within iSGS and iLTS is morphologically abnormal. Although both iSGS and iLTS have reduced epithelial thickness, ciliary cells, and secretory cells, only iSGS had significant increases in pathological basal cell expression. These data suggest that the epithelium in iSGS and iLTS play a common role in the pathogenesis of fibrosis in these two etiologies of laryngotracheal stenosis., Setting: Tertiary referral center (2017-2020)., Level of Evidence: NA Laryngoscope, 132:2194-2201, 2022., (© 2022 The Authors. The Laryngoscope published by Wiley Periodicals LLC on behalf of The American Laryngological, Rhinological and Otological Society, Inc.)

Background: Tracheal stenosis (TS) is a complication of prolonged intubation, tracheotomy, and tracheal surgery that compromises the vascular supply. Animal models are essential for studying its pathophysiology and the effect of interventions., Objective: To establish a TS model in rats secondary to tracheal autotransplantation with a graft submerged in bleomycin (Atx-Bleo). Additionally, to evaluate the clinical and histological changes, as well as the expression of newly formed collagen (NFC), isoforms of transforming growth factor beta (TGFβ), fibronectin (FN), elastin (ELN), integrin β1 (ITGβ1), and matrix metalloproteinase 1 (MMP1) in TS., Methods: Twenty Wistar rats were divided into three groups: group I (n = 20) control; group II (n = 10) end-to-end anastomosis of the trachea (tracheoplasty); and group III (n = 10) Atx-Bleo. The animals were evaluated clinically, tomographically, macroscopically, morphometrically, and microscopically. NFC deposition, and the expression of profibrotic and antifibrotic proteins were evaluated in tracheal scars., Results: All animals survived the surgical procedure and the study period. Compared with the other study groups, the Atx-Bleo group developed TS and fibrosis, exhibited higher expression of NFC, TGFβ1, TGFβ2, FN, ELN, and ITGβ1, and mild expression of TGFβ3 and MMP1 (p < 0.005; analysis of variance, Dunnett and Tukey tests)., Conclusion: Atx-Bleo in TS model rats produces tomographic and histological changes, and induces the upregulation of profibrotic proteins (TGFβ1, TGFβ2, collagen, FN, ELN, ITGβ1) and downregulation of antifibrotic proteins (TGFβ3, MMP1). Therefore, this model may be used to test new pharmacological treatments for reversing or preventing TS, and conduct basic studies regarding its pathophysiology.

Malignancy during pregnancy complicates approximately 0.1% of patients. Primary tumors of the trachea comprise only 0.2% of respiratory system malignancies. Adenoid cystic carcinoma (ACC) is an adenocarcinoma that can originate from the seromucinous submucosal glands of the trachea and cause airway obstruction. Here we present the collaborative operative management of a Cesarean section delivery for a patient with critical airway obstruction secondary to ACC., (Copyright © 2021 Elsevier Inc. All rights reserved.)

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.

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., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Tracheal stenosis is a refractory and recurrent disease induced by excessive cell proliferation within the restricted tracheal space. We investigated the role of extracellular signal-regulated kinase (ERK), which mediates a broad range of intracellular signal transduction processes in tracheal stenosis and the therapeutic effect of the MEK inhibitor which is the upstream kinase of ERK. We histologically analyzed cauterized tracheas to evaluate stenosis using a tracheal stenosis mouse model. Using Western blot, we analyzed the phosphorylation rate of ERK1/2 after cauterization with or without MEK inhibitor. MEK inhibitor was intraperitoneally injected 30 min prior to cauterization (single treatment) or 30 min prior to and 24, 48, 72, and 96 hours after cauterization (daily treatment). We compared the stenosis of non-inhibitor treatment, single treatment, and daily treatment group. We successfully established a novel mouse model of tracheal stenosis. The cauterized trachea increased the rate of stenosis compared with the normal control trachea. The phosphorylation rate of ERK1 and ERK2 was significantly increased at 5 min after the cauterization compared with the normal controls. After 5 min, the rates decreased over time. The daily treatment group had suppressed stenosis compared with the non-inhibitor treatment group. p-ERK1/2 activation after cauterization could play an important role in the tracheal wound healing process. Consecutive inhibition of ERK phosphorylation is a potentially useful therapeutic strategy for tracheal stenosis., Competing Interests: The authors have declared that no competing interests exist.

Background: Among the several complications associated with anterior cervical discectomy and fusion (ACDF), airway compromise is considered one of the serious life-threatening conditions and usually requires emergent treatment, including airway establishment and hematoma evacuation surgery. Postoperative retropharyngeal hematoma commonly occurred during the on immediate phase with airway compromise, but have a rarity on late onset of this complication. Enlightened by this existing fact, we report the first case of delayed onset postoperative retropharyngeal hematoma after anterior cervical surgery with a sequela of tracheal stricture., Case Presentation: A 55-year-old male underwent ACDF for disc herniation at C5-6 that had not responded to conservative treatment over 3 months. The symptoms significantly improved after surgery, and he was discharged on postoperative day 3. On the 7 days after ACDF, the patient complained of sudden-onset left-deviated neck swelling. The follow-up plain radiographs and neck-enhanced computed tomography (CT) scans showed anterior and right lateral displacement of the airway including the trachea by a large retropharyngeal hematoma. We performed an emergent forceful endotracheal intubation that was maintained for 2 days until the patient underwent hematoma evacuation surgery. On the second day after hematoma evacuation surgery, the patient complained of hoarseness with a foul breath odor. Laryngoscopy showed tracheal ischemic mucosal damage that had been induced by forceful endotracheal intubation. Antibiotics and systemic corticosteroids were administered, and the symptoms improved. One month after hematoma evacuation surgery, he complained of dyspnea on exertion, and laryngoscopy showed tracheal stricture. The patient underwent bronchoscopic dilatation and is doing well without recurrence of symptoms., Conclusions: Early surgery to remove the delayed onset retropharyngeal hematoma, rather than forceful endotracheal intubation followed by delayed surgery, might yield better results and avoid unexpected complications of tracheal stricture., (© 2021. The Author(s).)

Objective/hypothesis: Determine if diagnostic findings from pre-operative multidisciplinary evaluations are associated with single surgery or overall success rates in pediatric laryngotracheal reconstruction (LTR)., Study Design: Retrospective cohort., Methods: Retrospective cohort study of patients undergoing LTR at a tertiary care children's hospital between January 01, 2008 and December 31, 2017. Success is defined as decannulation rate if tracheostomy present, and resolution of symptoms if tracheostomy not present. Cohorts compared were those who did and did not receive pulmonary and gastrointestinal preoperative testing. Multivariate, logistic regression, and Kaplan Meier analyses performed., Results: About 165 children were included in the study. Median age was 3 years at the time of surgery; 73% of LTRs were double-stage procedures. Single surgery and overall success rates were 75% and 87%, respectively. After adjusting for severity of stenosis and surgical approach, performing esophagogastroduodenoscopy (EGD) and normal gross appearance on EGD were associated with increased single surgery (P = .01, .005) and overall success (P = .005, .0003). Performing pH probe and normal EGD biopsy results was associated with increased overall success (P = .03, .007). Asthma and musculoskeletal comorbidities, postoperative complications, and need for postoperative balloon dilation were associated with decreased success. No other comorbidities evaluated impacted success., Conclusions: Aerodigestive comorbidities are common in children undergoing LTR, and preoperative multidisciplinary workup often results in changes in management. After adjusting for grade and level of stenosis and staged approach, performing EGD and pH/impedance probe as well as normal gross and microscopic EGD findings was independently associated with increased LTR surgical success., Level of Evidence: 4 (retrospective cohort study) Laryngoscope, 131:E2356-E2362, 2021., (© 2020 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives: Iatrogenic laryngotracheal stenosis (iLTS) is the pathological narrowing of the glottis, subglottis, and/or trachea due to scar tissue. Patients with type 2 diabetes mellitus (T2DM) are over 8 times more likely to develop iLTS and represent 26% to 53% of all iLTS patients. In this investigation, we compared iLTS scar-derived fibroblasts in patients with and without T2DM., Study Design: Controlled ex vivo study., Methods: iLTS scar fibroblasts were isolated and cultured from subglottic scar biopsies in iLTS patients diagnosed with or without type 2 diabetes (non-T2DM). Fibroblast proliferation, fibrosis-related gene expression, and metabolic utilization of oxidative phosphorylation (OXPHOS) and glycolysis were assessed. Contractility was measured using a collagen-based assay. Metabolically targeted drugs (metformin, phenformin, amobarbital) were tested, and changes in fibrosis-related gene expression, collagen protein, and contractility were evaluated., Results: Compared to non-T2DM, T2DM iLTS scar fibroblasts had increased α-smooth muscle actin (αSMA) expression (8.2× increased, P = .020), increased contractility (mean 71.4 ± 4.3% vs. 51.7 ± 16% Δ area × 90 minute -1 , P = .016), and reduced proliferation (1.9× reduction at 5 days, P < .01). Collagen 1 (COL1) protein was significantly higher in the T2DM group (mean 2.06 ± 0.19 vs. 0.74 ±.44 COL1/total protein [pg/μg], P = .036). T2DM iLTS scar fibroblasts had increased measures of OXPHOS, including basal respiration (mean 86.7 vs. 31.5 pmol/minute/10 μg protein, P = .016) and adenosine triphosphate (ATP) generation (mean 97.5 vs. 25.7 pmol/minute/10 μg protein, P = .047) compared to non-T2DM fibroblasts. Amobarbital reduced cellular contractility; decreased collagen protein; and decreased expression of αSMA, COL1, and fibronectin. Metformin and phenformin did not significantly affect fibrosis-related gene expression., Conclusion: T2DM iLTS scar fibroblasts demonstrate a myofibroblast phenotype and greater contractility compared to non-T2DM. Their bioenergetic preference for OXPHOS drives their increased contractility, which is selectively targeted by amobarbital., Level of Evidence: NA Laryngoscope, 131:1570-1577, 2021., (© 2020 American Laryngological, Rhinological and Otological Society Inc, "The Triological Society" and American Laryngological Association (ALA).)

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.

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., (© 2020 The American Laryngological, Rhinological and Otological Society, Inc.)

Tracheal stenosis following injury cannot be effectively treated. The current study compared the protective effects of different anti‑inflammatory drugs on tracheal stenosis and investigated their possible mechanisms. Rabbit tracheal stenosis models following injury were constructed and confirmed using hematoxylin and eosin (H&E) staining. A total of 30 rabbits were divided into the control (CON), penicillin (PEN), erythromycin (ERY), budesonide (BUD) and PEN + ERY + BUD groups (n=6). Stenotic tracheal tissue, serum and bronchoalveolar lavage fluid (BALF) were collected 10 days after continuous treatment. Pathological changes in the tracheas were observed by H&E staining. Histone deacetylase 2 (HDAC2) expression in tracheal tissues was detected by immunofluorescence. Immunohistochemistry was performed to detect collagen I (Col‑I) and collagen III (Col‑III) levels in tracheal tissues. Transforming growth factor β1 (TGF‑β1), vascular endothelial growth factor (VEGF) and interleukin 8 (IL‑8) levels in serum and BALF samples were determined using ELISA kits. Western blotting detected HDAC2, IL‑8, TGF‑β1 and VEGF levels in tracheal tissues. H&E staining demonstrated that tracheal epithelial hyperplasia and fibroblast proliferation in the ERY and PEN + ERY + BUD groups markedly improved compared with the CON group. Furthermore, in tracheal tissues, HDAC2 expression was significantly increased and IL‑8, TGF‑β1, VEGF, Col‑I and Col‑III levels were significantly decreased in the ERY and PEN + ERY + BUD groups compared with the CON group. Additionally, the results for the PEN + ERY + BUD were more significant compared with the ERY group. In serum and BALF samples, IL‑8, TGF‑β1 and VEGF levels in the ERY and PEN + ERY + BUD groups were significantly lower compared with the CON group, with the results of the PEN + ERY + BUD group being more significant compared with the ERY group. There were no significant differences between the PEN, BUD and CON groups. ERY inhibited tracheal granulation tissue proliferation and improved tracheal stenosis following injury and synergistic effects with PEN and BUD further enhanced these protective effects. The mechanism may involve HDAC2 upregulation and inhibition of local airway and systemic inflammatory responses.

To apply a new airway treatment to humans, preclinical studies in an appropriate animal model is needed. Canine, porcine and leporine tracheas have been employed as animal airway stenosis models using various methods such as chemical caustic agents, laser, and electrocautery. However, existing models take a long time to develop (3-8 weeks) and the mechanism of stenosis is different from that in humans. The aim of the present study was to establish a new and fast tracheal stenosis model in pigs using a combination of cuff overpressure intubation (COI) and electrocautery. Fourteen pigs were divided into three groups: tracheal cautery (TC) group (n=3), COI group (n=3), and COI-TC combination group (n=8). Cuff overpressure (200/400/500 mmHg) was applied using a 9-mm endotracheal tube. Tracheal cautery (40/60 watts) was performed using a rigid bronchoscopic electrocoagulator. After intervention, the pigs were observed for 3 weeks and bronchoscopy was performed every 7 days. When the cross-sectional area decreased by > 50%, it was confirmed that tracheal stenosis was established. The time for tracheal stenosis was 14 days in the TC group and 7 days in the COI-TC combination group. In the COI group, no stenosis occurred. In the COI-TC group, electrocautery (40 watts) immediately after intubation for >1 h with a cuff pressure of 200 mmHg or more resulted in sufficient tracheal stenosis within 7 days. Moreover, the degree of tracheal stenosis increased in proportion to the cuff pressure and tracheal intubation time. The combined use of cuff overpressure and electrocautery helped to establish tracheal stenosis in pigs rapidly.

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., (© 2020 American Laryngological, Rhinological and Otological Society Inc, The Triological Society and American Laryngological Association (ALA).)

Purpose: Congenital tracheal stenosis is a disease in which complete tracheal cartilage rings (CTCR) cause airway narrowing. Although tracheal cartilage malformation has been suggested as a cause of CTCR, no histological studies have been performed. Here, we report a comparison of the tissues from CTCR and normal tracheal cartilage., Methods: Thirty-one infants who underwent slide tracheoplasty at our institution from May 2016 to August 2019 were included. Tissues from ten autopsy cases without tracheal lesions were used as controls. The survey items were tracheal cartilage cell density, cartilage thickness, and chondrocyte findings., Results: The median cartilage cell density from cases was 23/125 × 125 µm 2 and from controls was 23.5/125 × 125 µm 2 (p = 0.90). The median cartilage thickness from cases was 689 µm and from controls was 840 µm (p = 0.11). Comparing the ventral and dorsal sides of the CTCR tissues, the cell density was significantly different (median ventral 23/125 × 125 µm 2 ; median dorsal 19.5/125 × 125 µm 2 ; p = 0.034). There were no significant findings in the chondrocytes of the CTCR tissues., Conclusion: CTCR tissues did not differ in cartilage density and thickness from normal tracheal cartilage.

Stent-related granulation tissue hyperplasia is a major complication that limits the application of stents in airways. In this study, an arsenic trioxide-eluting electrospun nanofiber-covered self-expandable metallic stent (ATO-NFCS) was developed. Poly-L-lactide-caprolactone (PLCL) was selected as the drug-carrying polymer. Stents with two different ATO contents (0.4% ATO/PLCL and 1.2% ATO/PLCL) were fabricated. The in vitro release in simulated airway fluid suggested that the total ATO release time was 1 d. The growth of human embryonic pulmonary fibroblasts (CCC-HPF-1), normal human bronchial epithelial cells and airway smooth muscle cells was inhibited by ATO. When embedded in paravertebral muscle, the nanofiber membrane showed good short-term and long-term biological effects. In an animal study, placement of the ATO-NFCS in the trachea through a delivery system under fluoroscopy was feasible. The changes in liver and kidney function 1 and 7 d after ATO-NFCS placement were within the normal range. On pathological examination, the heart, liver, spleen, lungs and kidneys were normal. The effectiveness of the ATO-NFCS in reducing granulation tissue hyperplasia and collagen deposition was demonstrated in the rabbit airway (n = 18) at 4 weeks. The present study preliminarily investigated the efficacy of the ATO-NFCS in reducing granulation tissue formation in the trachea of rabbits. The results suggest that the ATO-NFCS is safe in vivo, easy to place, and effective for the suppression of granulation tissue formation.

Objectives/hypothesis: Identify predictors of decannulation failure after cricotracheal resection (CTR) and thyrotracheal anastomosis (TTA) in patients with subglottic stenosis (SGS)., Study Design: Retrospective cohort study., Methods: Charts of patients undergoing CTR and TTA for SGS at the University Health Network, Toronto, Ontario, Canada between 1988 and 2017 were reviewed. Patient, pathology, treatment, and outcome data were collected. The end points for statistical analysis were development of restenosis and permanent tracheostomy., Results: One hundred fourteen patients (n = 114) were eligible for inclusion in this review. The mean age at primary resection was 46.9 years, 95 (83%) were females, and 19 (17%) were males. The rate of restenosis and permanent tracheostomy was 13% and 5%, respectively. Sixty-two patients (54%) underwent a CTR and TTA, and 52 patients (46%) underwent a CTR, laryngofissure, and TTA. Traumatic stenosis (odds ratio [OR] = 10.3, P = .017), longer T-tube duration (OR = 1.2, P = .011), combined glottic/subglottic stenosis (OR = 10.47, P = .010), start of the stenosis at the vocal cords (OR = 6.6, P = .029), postoperative minor complications (OR = 13.6, P = .028), and need for repeat surgery (OR = 44.1, P < .001) were associated with an increased risk of requiring permanent tracheostomy., Conclusions: CTR and TTA are excellent surgical approaches for adult patients with subglottic stenosis. In this study, 5% of patients required permanent tracheostomy. Factors predicting treatment failure include traumatic stenosis, longer T-tube duration, combined glottic/subglottic stenosis, start of stenosis at the level of vocal cords, postoperative minor complications, and need for repeat surgery., Level of Evidence: 4 Laryngoscope, 130:1634-1639, 2020., (© 2019 The American Laryngological, Rhinological and Otological Society, Inc.)

Tracheal reconstruction is a complex surgical procedure that requires a well-trained, multidisciplinary team to achieve optimal results. No reviews or case reports involving the use of a healthy tracheal bridge to achieve reconstruction after extensive tracheal resection (greater than 7 cm) are described. We present a clinical case of a patient with double tracheal stenosis secondary to prolonged intubation and tracheostomy for which a healthy, well-vascularized tracheal bridge was used to achieve a tracheal reconstruction without tension. The key point in performing this type of reconstruction is allowing a tension-free cervical and thoracic anastomosis., (Copyright © 2020 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Laryngotracheal stenosis (LTS) is a pathologic narrowing of the subglottis and trachea leading to extrathoracic obstruction and significant shortness of breath. LTS results from mucosal injury from a foreign body in the trachea, leading to tissue damage and a local inflammatory response that goes awry, leading to the deposition of pathologic scar tissue. Treatment for LTS is surgical due to the lack of effective medical therapies. The purpose of this method is to construct a biocompatible stent that can be miniaturized to place into mice with LTS. We demonstrated that a PLLA-PCL (70% poly-L-lactide and 30% polycaprolactone) construct had optimal biomechanical strength, was biocompatible, practicable for an in vivo placement stent, and capable of eluting drug. This method provides a drug delivery system for testing various immunomodulatory agents to locally inhibit inflammation and reduce airway fibrosis. Manufacturing the stents takes 28-30 h and can be reproduced easily, allowing for experiments with large cohorts. Here we incorporated the drug rapamycin within the stent to test its effectiveness in reducing fibrosis and collagen deposition. Results revealed that PLLA-PCL tents showed reliable rapamycin release, were mechanically stable in physiological conditions, and were biocompatible, inducing little inflammatory response in the trachea. Further, the rapamycin-eluting PLLA-PCL stents reduced scar formation in the trachea in vivo.

Development of tracheal surgery was associated with introduction of fundamentally new procedures: two-level reconstruction, redo tracheal resection, tracheal resection with simultaneous dissection of tracheoesophageal fistula. There are combined and staged techniques when tracheal repair or endoscopic interventions are performed as a stage before circular resection of trachea. However, a single algorithm for prevention and correction of postoperative complications is still absent in tracheal surgery. Further development of tracheal surgery directly depends on introduction of preventive measures and analysis of adverse factors associated with increased risk of complications. In this regard, ongoing researches in this area are very perspective.

In this paper we describe the case of an 81-year-old Caucasian female (142 cm tall, weighing 45 kg) who suffered from a multinodular goiter for approximately 40 years. Following the onset of a clinical condition characterized by acute respiratory failure, she was transported to the emergency room by ambulance, where she died within a few hours after admission. A recent cardiac examination showed the absence of risk factors for cardiovascular disease, sinus tachycardia with a heart rate of 131 bpm, negative objectivity for signs of cardiocirculatory failure, a blood pressure of 120/80 mmHg and modest exertional dyspnea. A recent hemochemical laboratory analysis showed a TSH value of 0.01microUI/mL, FT3 value of 4.76 pg/mL and FT4 value of 2.33 ng/mL, pointing to a pattern of hyperthyroidism, attributable to Basedow's goiter. Autopsy showed some peculiarities, and we came across two extremely rare findings; the thyroid gland had reached a very large size in relation to the patient's body mass (1510 g, in a patient of 142 cm and 45 kg), and the death of the patient was due to the development of a massive intra-thyroid hemorrhage that had caused acute external compression of the trachea. To the best of our knowledge this very rare event has not previously been reported in the international scientific literature.

Background: Slide tracheoplasty is the preferred approach for treating long-segment congenital tracheal stenosis (CTS). However, little research has been conducted on the tracheobronchial anatomy before and after slide tracheoplasties in patients with CTS., Methods: We reviewed 23 patients with CTS who received slide tracheoplasties. We measured the intrathoracic tracheal length and the carina angle from computed tomography images. To account for each patient's body size, we divided the intrathoracic tracheal length by the length of the thorax to obtain the trachea-thorax ratio (TTR). These measurements were used to compare patients before and after slide tracheoplasties as well as normal control subjects., Results: Two patients had upper tracheal CTS and 21 patients had lower tracheal CTS. For the 21 patients with lower tracheal stenosis, their TTRs before slide tracheoplasty were 0.42 ± 0.04, which were significantly larger than those of the control subjects (0.32 ± 0.04; p < 0.0001). After slide tracheoplasty, the TTR was 0.32 ± 0.04, similar to the control TTRs (p = 0.94). The carina angle was significantly wider in the 21 patients than in the control subjects (120.7 ± 11.7 degrees versus 86.4 ± 13.1 degrees; p < 0.0001). After slide tracheoplasty, the carina angle was significantly narrower (from 120.7 ± 11.7 degrees to 92.2 ± 15.2 degrees; p < 0.0001), which was similar to control subjects., Conclusions: The trachea was longer and the carina angle wider in patients with lower tracheal CTS than in control subjects. Excessive tracheal length is favorable for slide tracheoplasty. Slide tracheoplasty not only corrects CTS, but also restores tracheobronchial morphology., (Copyright © 2019 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

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., (Copyright © 2019 Hillel et al.)

Introduction:  Tracheal reconstruction for long-segment stenosis remains challenging. We investigate the usefulness of BIOTUBE, an in-body tissue-engineered collagenous tube with a biodegradable stent, as a novel tracheal scaffold in a beagle model., Materials and Methods:  We prepared BIOTUBEs by embedding specially designed molds, including biodegradable stents, into subcutaneous pouches in beagles. After 2 months, the molds were filled with ingrown connective tissues and were harvested to obtain the BIOTUBEs. The BIOTUBEs, cut to 10- or 20-mm lengths, were implanted to replace the same-length defects in the cervical trachea of five beagles. Endoscopic and fluoroscopic evaluations were performed every week until the lumen became stable. The trachea, including the BIOTUBE, was harvested and subjected to histological evaluation between 3 and 7 months after implantation., Results:  One beagle died 28 days after 20-mm BIOTUBE implantation because of insufficient expansion and retention force of the stent. The remaining four beagles were implanted with a BIOTUBE reinforced by a strong stent, and all survived the observation period. Endoscopy revealed narrowing of the BIOTUBEs in all four beagles, due to an inflammatory reaction, but patency was maintained by steroid application at the implantation site and balloon dilatation against the stenosis. After 2 months, the lumen gradually became wider. Histological analyses showed that the internal surface of the BIOTUBEs was completely covered with tracheal epithelial cells., Conclusion:  This study demonstrated the usefulness of the BIOTUBE with a biodegradable stent as a novel scaffold for tracheal regeneration., Competing Interests: Dr. Hiwatashi reports grants from Ministry of Education, Culture, Sports, Science, and Technology and from JMS Co., Ltd., during the conduct of the study. In addition, Dr. Hiwatashi has a patent JP2018–014172 pending., (Georg Thieme Verlag KG Stuttgart · New York.)

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., (© 2018 The American Laryngological, Rhinological and Otological Society, Inc.)

Background: Balloon dilation is a primary treatment for nonmalignant tracheobronchial stenosis, but often requires multiple treatment sessions to maintain therapeutic efficacy. No guideline is available to suggest the appropriate maximum number of treatment sessions. This study aimed to investigate the relationship between the number of balloon dilation sessions and its long-term therapeutic effectiveness in Chinese patients with nonmalignant central airway stenosis., Methods: A total of 111 patients with nonmalignant central airway stenosis treated with flexible bronchoscopic balloon dilation from January 2005 to September 2012 were included. The cumulative long-term effective rate was compared between any two adjacent sessions of balloon dilation treatment by McNemar's test. Multivariate Cox regression was performed to investigate the independent factors associated with long-term effectiveness., Results: The cumulative long-term effective rate was significantly increased between any two adjacent sessions before the 6th session of treatment (all p < 0.05) but was no longer significantly increased after the 6th session. The stenosis diameter was larger in the patients receiving ⩽6 treatment sessions than those receiving ⩾6 treatment sessions. Multivariate Cox regression showed that the treatment session was an independent factor associated with long-term effectiveness (hazard ratio = 0.65, 95% confidence interval: 0.57-0.76, p < 0.001)., Conclusion: These results suggest that the maximum number of treatment sessions of balloon dilation may be six, and patients requiring more treatment sessions were more likely to have delayed long-term effectiveness.

Tracheal stenosis caused by congenital anomalies, tumors, trauma, or intubation-related damage can cause severe breathing issues, diminishing the quality of life, and potentially becoming fatal. Current treatment methods include laryngotracheal reconstruction or slide tracheoplasty. Laryngotracheal reconstruction utilizes rib cartilage harvested from the patient, requiring a second surgical site. Slide tracheoplasty involves a complex surgical procedure to splay open the trachea and reconnect both segments to widen the lumen. A clear need exists for new and innovative approaches that can be easily adopted by surgeons, and to avoid harvesting autologous tissue from the patient. This study evaluated the use of an electrospun patch, consisting of randomly layered polycaprolactone (PCL) nanofibers enveloping 3D-printed PCL rings, to create a mechanically robust, suturable, air-tight, and bioresorbable graft for the treatment of tracheal defects. The study design incorporated two distinct uses of PCL: electrospun fibers to promote tissue integration, while remaining air-tight when wet, and 3D-printed rings to hold the airway open and provide external support and protection during the healing process. Electrospun, reinforced tracheal patches were evaluated in an ovine model, in which all sheep survived for 10 weeks, although an overgrowth of fibrous tissue surrounding the patch was observed to significantly narrow the airway. Minimal tissue integration of the surrounding tissue and the electrospun fibers suggested the need for further improvement. Potential areas for further improvement include a faster degradation rate, agents to increase cellular adhesion, and/or an antibacterial coating to reduce the initial bacterial load.

Benign airway stenosis is a clinical challenge because of recurrent granulation tissues. Our previous study proved that a Chinese drug, β-elemene, could effectively inhibit the growth of fibroblasts cultured from hyperplastic human airway granulation tissues, which could slow down the progression of this disease. The purpose of the present study is to find out the mechanism for this effect. We cultured fibroblasts from normal human airway tissues and human airway granulation tissues. These cells were cultured with 160 μg/ml normal saline (NS), different doses of β-elemene, or 10 ng/ml canonical Wnt/β-catenin pathway inhibitor (Dickkopf-1, DKK-1). The proliferation rate of cells and the expression of six molecules involved in canonical Wnt/β-catenin pathway, Wnt3a, glycogen synthase kinase-3β (GSK-3β), β-catenin, α-smooth muscle actin (α-SMA), transforming growth factor-β (TGF-β), and Collagen I (Col-I), were measured. At last, we used canonical Wnt/β-catenin pathway activator (LiCl) to further ascertain the mechanism of β-elemene. Canonical Wnt/β-catenin pathway is activated in human airway granulation fibroblasts. β-Elemene didn't affect normal human airway fibroblasts; however, it had a dose-responsive inhibitive effect on the proliferation and expression of Wnt3a, non-active GSK-3β, β-catenin, α-SMA, TGF-β, and Col-I of human airway granulation fibroblasts. More importantly, it had the same effect on the expression and nuclear translocation of active β-catenin. All these effects were similar to 10 ng/ml DKK-1 and could be attenuated by 10 mM LiCl. Thus, β-elemene inhibits the proliferation of primary human airway granulation fibroblasts by down-regulating canonical Wnt/β-catenin pathway. This pathway is possibly a promising target to treat benign tracheobronchial stenosis., (© 2018 The Author(s).)

Subglottic stenosis refers to narrowing of the airway diameter below the vocal folds and may be congenital or acquired. Typical signs and symptoms range from recurrent croup and exertional stridor to complete airflow obstruction requiring tracheotomy. Management of moderate and severe subglottic stenosis often requires intricate surgical techniques. To optimize the success of these surgeries, a thorough assessment of the child's airway, lungs, reflux, and swallow needs to be evaluated. In order to provide concerted and coordinated care between typically otolaryngology (ENT), pulmonary, gastroenterology (GI), speech, swallow and language pathologists (SLP), "aerodigestive" teams have been developed and increasing in prevalence at children's medical hospitals. This article sets out to provide a brief overview of an aerodigestive program and evaluation, review a few of the more common laryngotracheal conditions, and the surgical techniques involved to augment the airway., (Copyright © 2018. Published by Elsevier Inc.)

Background: Patients with endotracheal intubation or tracheostomy are subject to benign tracheal stenosis (TS), for which current therapies are unsatisfactory. We conducted a preliminary investigation of drugs and drug combinations for the prevention and treatment of TS in a rabbit model., Methods: Fifty-four rabbits were apportioned into nine groups according to treatment: sham-operated control; untreated TS model; amikacin; budesonide; erythromycin; penicillin; amikacin + budesonide; erythromycin + budesonide; and penicillin + budesonide. TS was induced by abrasion during surgery. The drugs were applied for 7 days before and 10 days after the surgery. Rabbits were killed on the eleventh day. Tracheal specimens were processed for determining alterations in the thicknesses of tracheal epithelium and lamina propria via hematoxylin and eosin. The tracheal mRNA (assessed by real-time quantitative polymerase chain reaction) expressions of the following fibrotic-related factors were determined: transforming growth factor-β1 (TGF- β1), collagen type I (COL1A1), collagen type III (COL3A1), and interleukin-17 (IL-17). The protein levels of TGF-β1, COL1A1, and COL3A1 were determined through immunohistochemistry and integrated optical densities., Results: Compared with all other groups, the untreated TS model had significantly thicker tracheal epithelium and lamina propria, and higher mRNA and protein levels of all targeted fibrotic factors. The mRNA and protein levels of the targeted fibrotic factors in all the drug-treated groups were lower than those of the untreated TS model, and differences were most significant in the erythromycin + budesonide group., Conclusions: Erythromycin combined with budesonide may reduce inflammation and modify fibrosis progression in TS after tracheal injury.

Background: Laryngotracheal stenosis (LTS) can be either congenital or acquired. Laryngeal stenosis is most often encountered after prolonged intubation. The mechanism for stenosis following intubation is believed to be hypertrophic scarring. Mesenchymal stem cells (MSCs) therapy has shown promising results in regenerative medicine. We aimed to systematically review the literature on MSC therapy for stenosis of the conductive airways., Methods: PubMed, EMBASE, Google Scholar and the Cochrane Library were systematically searched from January 1980-January 2017 with the purpose of identifying all studies addressing the effect of MSC therapy on the airway. We assessed effect on inflammation, fibrosis, and MSC as a component in tissue engineering for treating defects in the airway., Results: We identified eleven studies (n = 256 animals) from eight countries evaluating the effect of MSCs as a regenerative therapy in the upper airways. The studies indicate that MSC therapy may lead to a more constructive inflammatory response as well as support tissue regeneration., Conclusion: There may be a favorable effect of MSCs in inhibiting inflammation and as a component in tissue engineering. Given the heterogeneous nature of the included animal studies, any clear conclusion regarding the effect of tracheal stenosis in human subjects cannot be drawn. The included preclinical studies are however encouraging for further research.

Objectives (1) Develop a novel method for serial assessment of gene and protein expression in laryngotracheal stenosis (LTS). (2) Assess cytokine expression and determine an immunophenotype in LTS. Study Design A matched comparison of endolaryngeal brush biopsy samples from laryngotracheal scar and normal airway. Setting Tertiary care hospital, 2015-2016. Methods Brush biopsy specimens of laryngotracheal scar and normal trachea were obtained from 17 patients with LTS at the time of operating room dilation and were used for protein and RNA extraction. Gene expression of the T H 1 cytokine interferon γ (INF-γ), T H 2 cytokine interleukin 4 (IL-4), transforming growth factor β, and collagen 1 (Coll1) was quantified with quantitative real-time polymerase chain reaction. Cytokine analysis was performed with flow cytometry with a cytometric bead array. Results LTS specimens demonstrated a 13.68-fold increase in Coll1 gene expression versus normal ( P < .001, N = 17). Additionally, IL-4 gene expression showed a 3.76-fold increase ( P < .001, N = 17) in LTS scar. When stratified into iatrogenic LTS and idiopathic subglottic stenosis cohorts, INF-γ gene expression was significantly increased in idiopathic subglottic stenosis ( P = .011). Soluble cytokine measurements were below the limit of detection for reliable quantification and thus could not be assessed. Conclusions Brush biopsies from LTS samples can be successfully utilized for RNA extraction and demonstrate the expected increase in Coll1 gene expression associated with LTS. Preliminary gene expression suggests that abnormal collagen production may be mediated by the T H 2 cytokine IL-4 and that increased INF-γ expression may represent a key difference between iatrogenic LTS and idiopathic subglottic stenosis. Further analysis of soluble cytokines is needed to confirm these findings.

Purpose: Airway stent placement is an effective treatment for the immediate palliation of malignant airway obstruction. However, restenosis caused by tumor ingrowth and/or overgrowth after stenting is common. The purpose of this study was to investigate the feasibility and safety of a novel self-expandable stent loaded with 125 I seeds in healthy beagle dog., Materials and Methods: Under fluoroscopic guidance, forty-eight self-expandable airway stents loaded with 125 I seeds were perorally placed in the main trachea of 48 healthy beagle dogs, who were randomly divided into four groups (Group A: 0.3 mCi; Group B: 0.6 mCi; Group C: 0.9 mCi; Control group: 0 mCi). The estimated radiation dose was calculated using the isotropic point source approximation. Radiological follow-up examinations and histopathological examinations of stented tracheal segments and their adjacent organs and tissues were performed at 2, 4, 8, and 16 weeks following the stenting., Results: All stents were successfully deployed in the targeted tracheal segment in the beagle dogs without procedure-related complications. Tracheal stenosis became severe gradually in all the four groups, which was not associated with the radioactivity of 125 I seeds (p > 0.05). The tracheal injury scores increased along with the higher dose of radioactive seeds which reached peak at 8 weeks and then turned back slightly at 16 weeks. The adjacent tissue did not show pathohistological changes under microscope, while mild and reversible ultrastructure changes were showed under electronic microscope., Conclusions: This study demonstrates that it is feasible and safe to insert this novel self-expandable airway stent loaded with 125 I seeds in healthy beagle dog.

Surgery of the trachea is a specialised field in which many disciplines work jointly due to the variety of indications and the extended topography. Not only because of its particular functional importance, but also because of its complex morphology, anatomy and physiology, this organ represents a special therapeutic challenge. A variety of diseases require surgical procedures of the trachea; the therapeutic strategy is influenced both by the disease itself as well as patient-dependent parameters. Regardless of the nature of the underlying disorder, good results require a high level of expertise in airway management, a careful diagnosis and interventional planning as well as an experienced surgical team that masters extended operative techniques. An optimal treatment decision always requires a multidisciplinary assessment of the patient's individual situation by interventional pulmonologists, thoracic surgeons, visceral surgeons, ENT (ear, nose and throat) surgeons and anaesthesiologists., Competing Interests: Interessenkonflikt: Nein., (Georg Thieme Verlag KG Stuttgart · New York.)

Objective To elucidate the role of hypoxia and inflammatory pathways in the pathogenesis of iatrogenic laryngotracheal stenosis (iLTS). Study Design (1) Examination of mucosal surface gene expression in human iLTS. (2) In vitro comparison of normal and scar laryngotracheal fibroblasts under normoxic and hypoxic conditions. Setting Tertiary care hospital in a research university (2012-2016). Subjects and Methods Brush biopsies were obtained from normal laryngotracheal tissue and scar in iLTS patients; gene expression was compared. Fibroblasts were isolated from normal and scarred trachea and grown in vitro in either a 1% O 2 or normoxic environment. Cell growth and gene and protein expression were compared. Statistical analysis utilized a multilevel mixed effects model. Results Expression of IL-6 (fold change = 2.8, P < .01), myofibroblast marker αSMA (fold change = 3.0, P = .01), and MMP13 (fold change = 5.4, P = .02) was significantly increased in scar biopsy samples as compared to normal. Under hypoxic conditions in vitro, normal laryngotracheal fibroblasts proliferated significantly faster (n = 8, P < .01 each day). Expression of IL-6 (n = 8, fold change = 2.6, P < .01) increased significantly after 12 hours under hypoxia. Expression of αSMA (n = 8, fold change= 2.0, P = .03), COL1 (n = 8, fold change = 1.1, P = .03), and MMP13 (n = 8, fold change = 1.6, P = .01) increased significantly after 48 hours under hypoxia. Scar fibroblasts also proliferated significantly faster under hypoxic conditions but did not display the same expression profile. Conclusion Human iLTS scar has a myofibroblast phenotype. Under hypoxic conditions in vitro, normal laryngotracheal fibroblasts can transdifferentiate into a similar phenotype. These changes may be mediated by IL-6, a fibrosis-related cytokine.

Background and Objective: Variable methods of animal model have been introduced to develop tracheal stenosis. However, none of the prior models allow for predictable determination of the grade of stenosis. This study sought to establish an animal model of tracheal stenosis by using a cylindrical diffuser and to evaluate the feasibility of a reproducible model., Study Design/materials and Methods: A cylindrical diffuser was developed to have a 5 mm active segment to emit laser light circumferentially. Twenty one New Zealand white rabbits were enrolled in this study. The cylindrical diffuser was inserted transorally under bronchoscopic view and the diffused light was delivered to tracheal mucosa 2 cm below the level of vocal cord. Input power of irradiation was 10 W, 5 seconds in group A (n = 7), 10 W, 7 seconds in group B (n = 7), and 8 W, 5 seconds in group C (n = 7). The degree of tracheal stenosis was observed weekly and the rabbits were euthanized 4 weeks after the laser irradiation., Results: The degree of stenosis in group B (90-98%) was significantly larger than that of group A (75-92%) (P = 0.004), while degree in group C (24-35%) was significantly smaller than that of group A (P < 0.001). Two rabbits of group A were euthanized at 3 weeks due to costal retraction. In group B, six rabbits died within 3 weeks after laser irradiation due to severe tracheal stenosis and tracheal malacia, while one rabbit was euthanized 16 days after the irradiation. All rabbits in group C survived up to 4 weeks. Survival between three groups showed significant difference (P = 0.001)., Conclusion: The degree of stenosis was significantly different according to the delivered optical energy to tracheal mucosa. Therefore, the proposed model may be used in animal studies to emulate variable grades of tracheal stenosis. Lasers Surg. Med. 49:372-379, 2017. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)