Long-term outcomes of tracheobronchial stenosis due to tuberculosis (TSTB) in symptomatic patients: airway intervention vs. conservative management

Azithromycin Prevents Subglottic Stenosis in Mice

OBJECTIVE

Pediatric subglottic stenosis (SGS) is characterized by subglottic narrowing which occurs when pathological fibroblasts deposit extracellular matrix that reduces airway patency. Recent clinical observations have suggested that azithromycin may have favorable impacts on SGS reduction while treating airway infections; furthermore, our recent work in mice demonstrated that the airway microbiome influences SGS. In this work, we characterize the protective effect of azithromycin as an immunomodulatory and antibacterial therapeutic against subglottic stenosis.

METHODS

Immunomodulatory and antifibrotic effects of azithromycin were assessed on TGF-β1-stimulated airway fibroblasts at 10 μg/mL for 5 days. Changes in gene expression were quantified by RT-qPCR and myofibroblast differentiation by α-SMA immunostaining. Murine airways were pretreated (2-weeks) with intranasal azithromycin before SGS injury by a twisted wire brush. Disease severity and immune response were characterized by histology and immunostaining for immune cells.

RESULTS

In vitro, azithromycin treatment of TGF-β1-stimulated fibroblasts exhibited strong reductions in extracellular matrix (COL1A1, LOX) and myofibroblast-related gene expression (ACTA2). Notably, there was a significant reduction in pro-fibrotic expression, which was observed with 10 μg/mL azithromycin. Immunostaining of fibroblasts for α-SMA revealed strong reductions in the number of positive-staining cells and the intensity of each positive cell. In vivo, azithromycin exhibited a significant decrease in lamina propria thickness indicative of reduced stenosis with associated changes in T-cell infiltration.

CONCLUSIONS

Overall, we show azithromycin prevents pro-fibrotic gene expression and myofibroblast differentiation and can help protect mice from developing SGS. This introduces azithromycin as a potential treatment for SGS.

LEVEL OF EVIDENCE

NA Laryngoscope, 2024.

Long-term outcomes of surgical reconstruction for post-tuberculosis tracheobronchial stenosis: a 7-year follow-up in a tuberculosis-endemic region

Background

Surgical reconstruction is often necessary for severe tracheobronchial stenosis resulting from tuberculosis (TB). However, the long-term efficacy of this approach remains unclear. This study investigated the safety and long-term outcomes of surgery for severe post-TB tracheobronchial stenosis.

Methods

We conducted a retrospective study of 48 patients with severe post-TB tracheobronchial stenosis who underwent surgical reconstruction between 2015 and 2018 in a TB-endemic region. Pre- and postoperative evaluations included Karnofsky performance status, modified Medical Research Council (mMRC) dyspnea scale, spirometry, chest computed tomography (CT) scan, and bronchoscopy. The primary outcome was intervention-requiring restenosis over the long term.

Results

The mean patient age was 30.6±9.9 years, with 91.7% females. Airway fibrosis was the predominant lesion (93.8%), affecting the bronchi (93.8%) and trachea (6.2%). All the patients underwent resection and anastomosis, and 56.2% required lobectomy. Postoperative complications occurred in 13 patients (27.1%), with prolonged air leaks being the most prevalent (12.5%). All complications resolved with conservative management. Significant improvements in performance status, dyspnea, and lung function were observed postoperatively and sustained for over 5 years. Within a median follow-up of 69 months, five cases of intervention-requiring restenosis occurred within the first year. The freedom from restenosis rate was 90% from 1 year onwards.

Conclusions

Surgical reconstruction is safe and effective in treating severe post-TB tracheobronchial stenosis. Larger studies are required to validate these findings.

Amelioration of Subglottic Stenosis by Antimicrobial Peptide Eluting Endotracheal Tubes

Introduction

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

Materials and Methods

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

Results

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

Conclusion

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

Supplementary Information

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

An effective case of bronchoscopic balloon dilatation for tuberculous bronchial stenosis

Endobronchial tuberculosis often causes bronchial stenosis. Balloon dilation is a minimally invasive and effective bronchoscopic intervention for bronchial stenosis; however, reports on balloon dilation in older individuals are limited. We present a case of a 77-year-old woman with endobronchial tuberculosis and clarify the efficacy and safety of balloon dilation. She presented with dyspnea, right lung atelectasis, and respiratory failure 55 days after initiation of antituberculosis therapy. We performed bronchoscopic balloon dilatation for the right main bronchial stenosis. Consequently, respiratory failure rapidly improved. Chest computed tomography (CT) showed improved lung atelectasis; however, severe bronchial stenosis and rhonchi persisted. Therefore, we performed a second balloon dilatation. CT 3 months after the first balloon dilation showed right upper bronchial stenosis and right lung middle lobe atelectasis. Restenosis was absent 21 months after third balloon dilatation. Bronchoscopic balloon dilation is effective for restenosis with repeated treatment and can be safely performed in older individuals.

The role of bronchoscopy in the multidisciplinary approach to benign tracheal stenosis

Benign tracheal stenosis can cause dyspnea, wheezing, and cough mimicking other obstructive lung diseases which often leads to a delay in the diagnosis. Risk factors and etiologies for tracheal strictures include autoimmune diseases, infection, gastro-esophageal reflux disease (GERD), radiation injury and iatrogenic factors such as post-intubation and post-tracheostomy. Once suspected, tracheal strictures are diagnosed by performing a thorough evaluation involving clinical exam, laboratory workup, pulmonary function test, chest imaging and bronchoscopy. Bronchoscopy plays a pivotal role in the diagnosis of stenosis and along with the imaging and physiologic assessments leads to a proper description of the stenosis based on all parameters that matters for management. Surgical resection provides a definitive management in most patients with idiopathic or post intubation/tracheostomy stenosis, however, factors such as severe co-morbidities, length and location of the stricture can preclude patients from undergoing curative surgery. Several bronchoscopic interventions including mechanical or laser assisted dilation, electrosurgery (ES), airway stenting and pharmacological treatment with mitomycin C (MMC) and intralesional steroid have been reported in the literature for management of patients who are not surgical candidates. Herein, we review the role of bronchoscopy and illustrate the importance of a multi-disciplinary team (MDT) approach comprising of interventional pulmonologists, thoracic surgeons and otorhinolaryngologists in the diagnosis and management of patients with benign tracheal stenosis.

Analysis of clinical characteristics of 617 patients with benign airway stenosis

Introduction

Benign airway stenosis (BAS), namely airway narrowing caused by a variety of benign lesions, can lead to varying degrees of breathing difficulties and even death due to asphyxia. This study aimed to elucidate the clinical characteristics of BAS, including etiology, treatment and pathology, by analyzing the clinical data of BAS patients.

Methods

A retrospective analysis was conducted using the clinical data of 617 BAS cases from January 2017 to December 2022. The pathological characteristics of the tissues were assessed by hematoxylin-eosin (H&E) and Masson's staining. Besides, protein expression levels were determined by immunohistochemistry (IHC).

Results

A total of 617 patients were included (333 females [53.97%] and 284 males [46.03%]), with an average age of 48.93 ± 18.30 (range 14-87). Tuberculosis (n = 306, 49.59%) and trauma (n = 179, 29.02%) were the two leading etiologies of BAS, followed by airway foreign bodies (FB, n = 74, 11.99%), external compression (n = 25, 4.05%) and other etiologies (n = 33, 5.35%). Among 306 tuberculous tracheobronchial stenosis (TBTS) cases, most were females (n = 215, 70.26%), and TBTS mainly occurred in the left main bronchus (n = 97, 31.70%), followed by the right middle bronchus (n = 70 cases, 22.88%). The majority of TBTS patients (n = 259, 84.64%) were treated by interventional therapy. The condition of 179 BAS patients was ascribed to trauma, such as tracheal intubation (n = 92, 51.40%), tracheotomy (n = 69, 38.56%), injury (n = 15, 8.38%) and surgery (n = 3, 1.68%), which mostly took place in the trachea (n = 173, 96.65%). TAS patients mainly received interventional therapy (n = 168, 93.85%) and stent implantation (n = 47, 26.26%). The granulation tissues of BAS primarily featured inflammation, proliferation and fibrosis. IHC indicated the up-regulated expressions of transforming growth factor-β1 (TGF-β1), α-smooth muscle actin (α-SMA), collagen type I protein (COL-I) and vimentin, and the down-regulated expression of E-cadherin, which indicated fibrosis and epithelial-mesenchymal transition (EMT).

Conclusion

Tuberculosis was the main etiology, and trauma was the secondary etiology. The granulation tissues of BAS were characterized by inflammation, fibrosis and probably EMT. Comprehensive interventional therapy is an effective method of treating BAS.

Balloon Bronchoplasty for the Treatment of Bronchial Stenosis After Lung Transplantation: A Single-Center 10-Year Experience

OBJECTIVE

To assess the safety and efficacy of balloon dilatation under dual guidance using fluoroscopy and bronchoscopy for treating bronchial stenosis following lung transplantation (LT), and to elucidate the factors associated with patency after the procedure.

MATERIALS AND METHODS

From September, 2012, to April, 2021, 50 patients (mean age ± standard deviation, 54.4 ± 12.2 years) with bronchial stenosis among 361 recipients of LT were retrospectively analyzed. The safety of balloon dilatation was assessed by evaluating procedure-related complications. Efficacy was assessed by evaluating the technical success, primary patency, and secondary patency. Primary and secondary cumulative patency rates were calculated using the Kaplan-Meier method. The factors associated with patency after the procedure were evaluated using multivariable Cox hazard proportional regression analysis.

RESULTS

In total, 65 bronchi were treated with balloon dilatation in 50 patients. The total number of treatment sessions was 277 and the technical success rate was 99.3% (275/277 sessions). No major procedure-related complications were noted. During the mean follow-up period of 34.6 ± 30.8 months, primary patency was achieved in 12 of 65 bronchi (18.5%). However, the patency rate improved to 76.9% (50 of 65 bronchi) after repeated balloon dilatation (secondary patency). The 6-month, 1-year, 3-year, and 5-year secondary patency rates were 95.4%, 90.8%, 83.1%, and 78.5%, respectively. The presence of clinical symptoms was a significant prognostic factor associated with reduced primary patency (adjusted hazard ratio [HR], 0.465; 95% confidence interval [CI], 0.220-0.987). Early-stage treatment ≤ 6 months (adjusted HR, 3.588; 95% CI, 1.093-11.780) and prolonged balloon dilatation > 5 min (adjusted HR, 3.285; 95% CI, 1.018-10.598) were associated with significantly higher secondary patency.

CONCLUSION

Repeated balloon dilatation was determined to be safe and effective for treating bronchial stenosis following LT. Early-stage treatment and prolonged balloon dilatation could significantly promote long-term patency.

Triamcinolone acetonide induces the autophagy of Ag85B-treated WI-38 cells via SIRT1/FOXO3 pathway

BACKGROUND

Tracheobronchial stenosis due to tuberculosis (TSTB) seriously threatens the health of tuberculosis patients. The inflammation and autophagy of fibroblasts affect the development of TSTB. Triamcinolone acetonide (TA) can regulate the autophagy of fibroblasts. Nevertheless, the impact of TA on TSTB and underlying mechanism has remained unclear.

OBJECTIVE

To study the impact of TA on TSTB and underlying mechanism.

MATERIAL AND METHODS

In order to simulate the TSTB-like model in vitro, WI-38 cells were exposed to Ag85B protein. In addition, the cell counting kit (CCK)-8 assay was applied to assess the function of TA in Ag85B-treated WI-38 cells. Quantitative real-time polymerase chain reaction was applied to detect the mRNA level of sirtuin 1 (SIRT1) and forkhead box O3 (FOXO3a), and autophagy-related proteins were evaluated by Western blot analysis. Vascular endothelial growth factor (VEGF) level was investigated by immunohistochemical staining. Enzyme-linked immunosorbent serologic assay was applied to detect the secretion of inflammatory cytokines. Furthermore, hematoxylin and eosin staining was applied to observe tissue injuries.

RESULTS

Ag85B affected WI-38 cell viability in a limited manner, while TA notably suppressed Ag85B-treated WI-38 cell viability. TA induced the apoptosis of Ag85B-treated WI-38 cells in a dose-dependent manner. In addition, Ag85B-treated WI-38 cells demonstrated the upregulation of interleukin (IL)-6, tumor necrosis factor-α (TNF-α), interferon gamma (IFN-γ), and fibrotic proteins (transforming growth factor-beta [TGF-β] and vascular endothelial growth factor [VEGF]), which can be significantly destroyed by the TA. Meanwhile, TA reversed Ag85-induced inhibition of cell autophagy by mediation of p62, LC3, and Beclin1. Furthermore, silencing of SIRT1/FOXO3a pathway could reverse the effect of TA on the autophagy of Ag85B-treated cells.

CONCLUSION

TA significantly induced the autophagy of fibroblasts in Ag85B-treated cells by mediation of SIRT1/FOXO3 pathway. This study established a new theoretical basis for exploring strategies against TSTB.

Management of stent-related tracheoesophageal fistula in complex post-tuberculosis tracheobronchial stenosis: A case report

Background

The covered self-expandable metallic stents (SEMS) have been used to manage benign tracheobronchial stenosis, especially the complex post-tuberculosis (TB) tracheobronchial stenosis (PTTS) with cartilage destruction or malacia. This procedure could lead to stent-related tracheoesophageal fistula (TEF).

Case presentation

A 21-year-old woman, who had one covered Y-shaped SEMS inserted to manage complex PTTS 2 years ago, presented with dyspnea and frequent coughing on drinking water. The bronchoscopy confirmed extensive granulation tissue hyperplasia and a TEF on the upper edge of the covered SEMS. The covered SEMS was removed in three steps, and another fully covered Y-shape SEMS (Microtech Co., Ltd., Nanjing, China) was inserted to restore patency in the tracheobronchial tree and occlude the TEF orifice. Recombinant bovine basic fibroblast growth factor (rbFGF) (6,000 IU/time) was sprayed into and around the fistula through the V-System single-use cannula via the flexible bronchoscope every other week. The patient showed sustained clinical and radiographic improvement, and the TEF healed.

Conclusion

We presented a three-step bronchoscopic approach to managing a stent-related TEF in a patient with complex PTTS. Subsequently, regular bronchoscopic debridement of granulation tissue developing on the upper edge of SEMS is necessary to maintain the stent patency and reduce the risk of recurrent stent-related TEF. A fully covered SEMS associated with the local administration of rbFGF seems to offer an alternative simplified one-stage procedure for the temporary management of TEF combined with complex PTTS in non-surgical candidates.

Central airway obstruction: is it time to move forward?

INTRODUCTION

Central airway obstruction (CAO) represents a pathological condition that can lead to airflow limitation of the trachea, main stem bronchi, bronchus intermedius or lobar bronchus.

MAIN BODY

It is a common clinical situation consensually considered under-diagnosed. Management of patients with CAO can be difficult and deciding on the best treatment approach represents a medical challenge. This work intends to review CAO classifications, causes, treatments and its therapeutic limitations, approaching benign and malign presentations. Three illustrative cases are further presented, supporting the clinical problem under review.

CONCLUSION

Management of CAO still remains a challenge. The available options are not always effective nor free from complications. A new generation of costume-tailored airway stents, associated with stem cell-based therapy, could be an option in specific clinical situations.

Left Main Bronchus Stenosis Lesion, Neutrophil Count, and Platelet Count Are Predictors of Post-Tuberculosis Bronchomalacia

Background

Post-tuberculosis bronchomalacia (PTBM) is one of the main conditions occurring in patients after tracheobronchial tuberculosis (TBTB), and is also associated with the recurrence of symptoms. The present study aimed to investigate the predictors of PTBM in patients who had been undergoing appropriate TB treatment.

Material/Methods

Clinical data of 104 patients with symptomatic airway stenosis after TBTB between January 01, 2019 and June 31, 2020 were recorded and analyzed. The association between baseline clinical characteristics, laboratory results, and PTBM was calculated with logistical regression. The time from onset of bronchoscopic intervention was examined by Kaplan-Meier estimates; differences between the 2 groups were tested by the log-rank test.

Results

Fifty-seven patients (54.81%) had PTBM. In the multivariate logistical analysis, the left main bronchus stenosis lesion (odds ratio [OR]=3.763), neutrophil (NEUT) count (OR=1.527), and platelet (PLT) (OR=1.010) count were predictors of PTBM. During follow-up, patients with BM had a significantly longer duration from onset of bronchoscopic intervention than patients without BM (hazard ratio=2.412, P<0.0001). Further, all patients needing long-term bronchoscopic intervention therapy were subsequently identified as having PTBM. Additionally, blood PLT counts were significantly decreased to normal levels in the non-BM group (P<0.05), but not in the BM group (P>0.05).

Conclusions

PTBM is most likely to occur in the left main bronchus. The inflammatory and immune responses associated with NEUT and PLT may represent therapeutic targets of PTBM. Our study is the first to report that decreased blood PLT count has the potential to monitor the treatment response.

Clinical significance of serum transforming growth factor-β1 and procollagen type I N-propeptide in post-tuberculosis tracheobronchial stenosis

Non-invasive strategies for monitoring post-tuberculosis (TB) tracheobronchial stenosis (PTTS) are clinically important but currently lacking. Transforming growth factor-β1 (TGF-β1) and procollagen type I N-propeptide (PINP) have been identified as markers of fibrosis. The present study aimed to investigate the clinical significance of serum TGF-β1 and PINP in PTTS. Serum samples were collected from 119 patients with tracheobronchial TB after the condition was treated for at least 6 months (59 patients with airway stenosis and 60 patients with no stenosis). Serum TGF-β1 and PINP levels were measured using ELISA and compared between the groups. Relationships between serum TGF-β1 and PINP levels and clinical characteristics, interventional bronchoscopy and outcomes of airway stenosis were analysed. The correlation between TGF-β1 and PINP, and their diagnostic efficacy for airway stenosis were also analysed. The TGF-β1 and PINP levels in the airway stenosis group were higher than those in the non-stenosis group. Furthermore, airway stenosis with atelectasis or mucus plugging was associated with higher TGF-β1 levels, and airway stenosis with atelectasis, mucus plugging, right main bronchus stenosis or severe airway tracheal stenosis was associated with higher PINP levels. In addition, TGF-β1 and PINP levels increased after interventional bronchoscopy therapy and airway stenosis with recurrent stenosis was associated with higher baseline levels of both markers. Finally, TGF-β1 levels were positively correlated with PINP levels in patients with airway stenosis. The area under the receiver operating characteristic curve of TGF-β1 and PINP for distinguishing airway stenosis from non-stenosis cases was 0.824 (95% CI: 0.748-0.900) and 0.863 (95% CI: 0.796-0.930), respectively. Therefore, TGF-β1 and PINP are potential biomarkers that may be useful for diagnosing and monitoring PTTS.

Topical mitomycin-C as an adjuvant to multimodal endoscopic treatment for tracheobronchial stenosis secondary to endobronchial tuberculosis

Tracheobronchial stenosis secondary to endobronchial tuberculosis (TSTB) is a rare but debilitating complication of endobronchial tuberculosis (EBTB). Topical mitomycin-C (TMC) has been successfully utilized to restore airway patency and to prevent recurrence of TSTB, although little is known about its exact efficacy. Here, we report the biggest case series to date involving seven patients who received TMC as part of multimodality endoscopic treatment for TSTB with varying levels of success. All patients presented with dyspnoea during or after treatment completion for pulmonary tuberculosis (PTB). Four patients had short-segment concentric membranous TSTB while two patients had concurrent bronchomalacia. Another one patient had a thick fibrotic band adjacent to luminal opening. We hypothesize that TMC is more efficacious in short membranous stenosis without concurrent bronchomalacia and/or thick fibrotic bands. More studies are needed to bridge the current gaps in knowledge regarding the optimal role and benefits of TMC for TSTB patients.

Conservative management of airway tear as a complication of silicone endobronchial stenting in bronchomalacia secondary to endobronchial tuberculosis

Tracheobronchial stenosis due to tuberculosis (TSTB) is a potentially debilitating complication of endobronchial tuberculosis (EBTB). Endobronchial interventions including silicone stent insertion is an acceptable approach to improve quality of life among patients with TSTB. However, little is known about the optimal management strategy for patients with bronchomalacia secondary to EBTB (B-EBTB) and whether stent-related complication rates are higher among this group of patients. Herein, we report two patients with B-EBTB who unfortunately developed bronchial tear related to silicone endobronchial stenting. Both patients were successfully managed conservatively without the need for emergency open surgery. We hypothesize that endobronchial intervention might be more beneficial for patients with pure TSTB and might be riskier in cases of bronchomalacia with reduced airway thickness and loss of airway cartilaginous support. More future studies are needed to bridge the current gap in knowledge regarding the optimal management and role of endobronchial interventions among patients with B-EBTB.