Objective To define the inflammatory cell infiltrate preceding fibrosis in a laryngotracheal stenosis (LTS) murine model. Study Design Prospective controlled murine study. Setting Tertiary care hospital in a research university. Subjects and Methods Chemomechanical injury mice (n=44) sustained bleomycin-coated wire-brush injury to the laryngotracheal complex while mechanical injury controls (n=42) underwent PBS-coated wire-brush injury. Mock surgery controls (n=34) underwent anterior transcervical tracheal exposure only. Inflammatory and fibrosis protein and gene expression was assessed in each condition. Immunohistochemistry served as a secondary outcome. Results In chemomechanical injury mice, there was an up-regulation of: Collagen I (p<0.0001, p<0.0001), Tgf-β (p=0.0023, p=0.0008), and elastin (p<0.0001, p<0.0001) on Day 7, acute inflammatory gene: Il1β (p=0.0027, p=0.0008) on Day 1, and macrophage gene: CD11b (p=0.0026, p=0.0033) on Day 1 versus mechanical and mock controls respectively. M1 marker iNOS expression decreased (p=0.0014) while M2 marker arg1 (p=0.0002) increased on Day 7 compared to mechanical controls. Flow cytometry demonstrated increased macrophages (p=0.0058, day 4) and M1 macrophages (p=0.0148, day 4, p=0.0343, day 7, p=0.0229, day 10) compared to mock controls. There were similarities between chemomechanical and mechanical injury mice with an increase in M2 macrophages at day 10 (p=0.0196). Conclusions The mouse model demonstrated increased macrophages involved with the development of LTS. Macrophage immunophenotype suggested that dysregulated M2 macrophages have a role in abnormal laryngotracheal wound healing in both species. These results support this animal model as a representation for human disease. Furthermore, this data delineates inflammatory cells and signaling pathways in LTS that may potentially be modulated to lessen fibroblast proliferation and collagen deposition.

Objective/Purpose Laryngotracheal stenosis (LTS) is a chronic fibrotic disease characterized by fibroblast proliferation, collagen deposition, and matrix remodeling in the lamina propria of the larynx and/or trachea. Current medical therapies are limited by a poor understanding of the effector cell’s (fibroblasts) cellular biology and metabolism. The purpose of this study is to compare cellular proliferation, function, and metabolism between normal and LTS-derived fibroblasts in vitro. Methods Human biopsies of normal and iatrogenic LTS tissue (n=7) were obtained and fibroblasts were isolated and cultured in vitro. Cellular proliferation, cellular histology, gene expression and metabolic analyses were performed. Statistical analyses comparing normal and scar-derived fibroblasts were performed. Results LTS fibroblast proliferation rate, cellular surface area, and collagen-1 expression were increased compared to normal fibroblasts. Cellular metabolic analysis of LTS-derived fibroblasts demonstrated reduced oxidative phosphorylation and increased glycolysis/oxidative phosphorylation ratio compared with normal fibroblasts. Conclusion Human iatrogenic LTS-derived fibroblasts demonstrated aberrant behavior when compared with normal fibroblasts. A Warburg-like effect was revealed suggesting human iatrogenic LTS fibroblasts drive their proliferation with aerobic glycolysis. The distinct metabolism suggests metabolic inhibitors could reduce fibroblast hyperplasia and hypertrophy in LTS and fibrosis in general.

Objective To assess intrinsic and extrinsic risk factors in the development of posterior glottic stenosis (PGS) in intubated patients. Methods PGS patients diagnosed between September 2012 – May 2014 at three tertiary care university hospitals were included. Patient demographics, comorbidities, duration of intubation, ETT size, and indication for intubation were recorded. PGS patients were compared to control patients represented by patients intubated in intensive care units (ICU). Results Thirty-six PGS patients were identified. After exclusion, 28 PGS patients (14 male, 14 female) and 112 (65 male, 47 female) controls were studied. Multivariate analysis demonstrated ischemia (p<0.05), diabetes (p<0.01), length of intubation (p<0.01) were significant risk factors for the development of PGS. 14/14 (100%) males were intubated with a size 8 or larger ETT compared to 47/65 (72.3%) male controls (p<0.05). PGS (p<0.01), length of intubation (p<0.001), and obstructive sleep apnea (p<0.05) were significant risk factors for tracheostomy. Conclusion Duration of intubation, ischemia, diabetes mellitus, and large ETT size (8 or greater) in males were significant risk factors for the development of PGS. Reducing the use of size 8 ETTs and earlier planned tracheostomy in high-risk patients may reduce the incidence of PGS and improve ICU safety.

Objective To determine if rapamycin inhibits the growth, function, and metabolism of human laryngotracheal stenosis (LTS)–derived fibroblasts. Study Design Controlled in vitro study. Setting Tertiary care hospital in a research university. Subjects and Methods Fibroblasts isolated from biopsies of 5 patients with laryngotracheal stenosis were cultured. Cell proliferation, histology, gene expression, and cellular metabolism of LTS-derived fibroblasts were assessed in 4 conditions: (1) fibroblast growth medium, (2) fibroblast growth medium with dimethylsulfoxide (DMSO), (3) fibroblast growth medium with 10−10 M (low-dose) rapamycin dissolved in DMSO, and (4) fibroblast growth medium with 10−9 M (high-dose) rapamycin dissolved in DMSO. Results The LTS fibroblast count and DNA concentration were reduced after treatment with high-dose rapamycin compared to DMSO (P = .0007) and normal (P = .0007) controls. Collagen I expression decreased after treatment with high-dose rapamycin versus control (P = .0051) and DMSO (P = .0093) controls. Maximal respiration decreased to 68.6 pMoles of oxygen/min/10 mg/protein from 96.9 for DMSO (P = .0002) and 97.0 for normal (P = .0022) controls. Adenosine triphosphate (ATP) production decreased to 66.8 pMoles from 88.1 for DMSO (P = .0006) and 83.3 for normal (P = .0003) controls. Basal respiration decreased to 78.6 pMoles from 108 for DMSO (P = .0002) and 101 for normal (P = .0014) controls. Conclusions Rapamycin demonstrated an anti-fibroblast effect by significantly reducing the proliferation, metabolism, and collagen deposition of human LTS fibroblast in vitro. Rapamycin significantly decreased oxidative phosphorylation of LTS fibroblasts, suggesting at a potential mechanism for the reduced proliferation and differentiation. Furthermore, rapamycin’s anti-fibroblast effects indicate a promising adjuvant therapy for the treatment of laryngotracheal stenosis.

Objective/Hypothesis: This prospective controlled human and murine study assessed the presence of inflammatory cells and cytokines to test the hypothesis that immune cells are associated with fibroproliferation in iatrogenic laryngotracheal stenosis (iLTS). Methods: Inflammation was assessed by histology and immunofluorescence (IF), quantitative real-time polymerase chain reaction (qRT-PCR), and flow cytometry of cricotracheal resections of iLTS patients compared to normal controls. An iLTS murine model assessed the temporal relationship between inflammation and fibrosis. Results: iLTS specimens showed increased inflammation versus normal controls (159/high power field [hpf] vs. 119/hpf, P = 0.038), and increased CD3 + T-cells, CD4 + cells, and CD3+/CD4 + T-helper (TH) 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 TH2 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 TH2 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.

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 seventeen LTS patients at the time of OR dilation and were used for protein and RNA extraction. Gene expression of the TH1 cytokine Interferon-ϒ (INF-ϒ), TH2 cytokine Interleukin (IL) – 4, Transforming Growth Factor – β, and Collagen-1 (Coll1) was quantified using quantitative RT-PCR. Cytokine analysis was performed with flow cytometry using a cytometric bead array. Results LTS specimens demonstrated a 13.68 fold increase in Coll1 gene expression compared to normal (p<0.001, n=17). Additionally, IL-4 gene expression showed a 3.76-fold increase (p<0.001, n=17) in LTS scar. When stratified into iatrogenic LTS (iLTS) and idiopathic subglottic stenosis (iSGS) cohorts INF-ϒ gene expression was significantly increased in iSGS (p=0.011). 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 abnormal collagen production may be mediated by the TH2 cytokine IL-4, and that increased INF-ϒ expression may represent a key difference between iLTS and iSGS. Further analysis of soluble cytokines is needed to confirm these findings.

IMPORTANCE Laryngotracheal stenosis (LTS) is a fibroproliferative disorder of the glottis, subglottis, and trachea. In models of fibrosis from other organ systems, the CD4+T-cell response has been shown to regulate extracellular matrix deposition. Specifically, helper T cell 2 (TH2) promotes fibrosis, whereas TH1 and associated cytokines have been shown to be antifibrotic. However, this antifibrotic effect of the TH1 response has not been demonstrated in LTS. OBJECTIVE To determine whether the TH1 cytokine interferon-γ inhibits the function of LTS-derived fibroblasts in vitro. DESIGN, SETTING, AND PARTICIPANTS This in vitro controlled study included 6 patients with iatrogenic LTS undergoing routine surgical subglottic and tracheal dilation at a single institution. Fibroblasts were isolated from biopsy specimens of laryngotracheal scar and normal-appearing trachea. The presence of fibroblasts was confirmed by an immunohistochemical analysis. Laryngotracheal stenosis–derived fibroblasts were treated with interferon-γ and compared with untreated controls (2 sets of untreated, LTS-derived fibroblasts [media did not contain interferon-γ]) and normal airway fibroblasts (fibroblasts isolated from normal trachea). Data were collected from August 2015 through June 2016. INTERVENTIONS Treatment with interferon-γ, 10 ng/mL. MAIN OUTCOMES AND MEASURES Cellular proliferation, fibrosis gene expression (using quantitative reverse transcription polymerase chain reaction analysis), soluble collagen, and cellular histologic features were assessed. RESULTS Among the 6 patients (6 women; mean [SD] age, 38.3 [17.2] years), LTS-derived fibroblast proliferation was reduced in patients who received interferon-γ treatment compared with untreated controls on days 3 (mean difference, −6515 cells; 95% CI, −10 630 to −2600 cells) to 6 (mean difference, −47 521 cells; 95% CI, −81285 to −13 757 cells). Interferon-γ treatment reduced collagen types I and III gene expression by 86% and 68%, respectively, and resulted in lower total collagen production (10.94 vs 14.89 μg/mL). In addition, interferon-γ treatment resulted in a 32% reduction in expression of transforming growth factor β in LTS-derived fibroblasts. CONCLUSIONS AND RELEVANCE Interferon-γ reduced proliferation, soluble collagen production, and collagen expression in LTS-derived fibroblasts while also reducing the expression of the profibrotic cytokine transforming growth factor β. These findings suggest that therapeutics aimed at increasing interferon-γ and the TH1 response could attenuate LTS.

Inverted papillomas (IPs) are rare benign tumors of nasal epithelium with high recurrence rates and malignant transformation potential. Their etiology is still uncertain, and the mechanism of their growth has not yet been fully described. The purpose of this study was to detect, quantify, and compare cell proliferation, apoptosis, and apoptosis inhibition in hyperplastic epithelium from IPs and in inflammatory nasal polyps (NPs). IP samples were obtained after surgical removal of tumor in 13 patients, and NPs were sampled during endoscopic ethmoidectomy in 10 patients with nasal polyposis. Cell proliferation and apoptosis inhibition, respectively, were assessed by immunohistochemical identification of the proliferating cell nuclear antigen (PCNA) and the oncoprotein Bcl‐2. Apoptosis was evaluated by analyzing the DNA fragmentation. Cell proliferation and apoptosis were significantly higher in IPs than in NPs (P = .0002 and P = .043, respectively), while apoptosis inhibition was significantly lower in IPs than in NPs (P = .001). Concerning IPs, cell proliferation was significantly higher than apoptosis (P = .0029) and apoptosis inhibition (P = .0015). The increase in epithelial cell proliferation seemed to be greater in IPs with dysplasia than in IPs without dysplasia. Increased epithelial cell proliferation, but not apoptosis and apoptosis inhibition, seems to be involved in the development of IP.