Imaging the pulmonary extracellular matrix

The pulmonary extracellular matrix (ECM) plays an important role in the structure and function of the lung. In many respiratory diseases the profile of the ECM reflects pathological changes. The capacity to visualize the ECM and its alterations is of considerable importance to facilitate a better understanding of pulmonary diseases and eventually augment therapeutic solutions. This short review summarizes the current and novel possibilities for imaging the pulmonary ECM by the use of computed tomography (CT), optical coherence tomography (OCT), confocal laser endomicroscopy (CLE) and molecular imaging. While not all these techniques are as yet implemented in standard clinical practice, we address their main features along with the key possibilities for the future

Airway wall extracellular matrix changes induced by bronchial thermoplasty in severe asthma

Background: Airway remodeling is a prominent feature of asthma, which involves increased airway smooth muscle mass and altered extracellular matrix composition. Bronchial thermoplasty (BT), a bronchoscopic treatment for severe asthma, targets airway remodeling.Objective: We sought to investigate the effect of BT on extracellular matrix composition and its association with clinical outcomes.Methods: This is a substudy of the TASMA trial. Thirty patients with severe asthma were BT-treated, of whom 13 patients were treated for 6 months with standard therapy (control group) before BT. Demographic data, clinical data including pulmonary function, and bronchial biopsies were collected. Biopsies at BT-treated and nontreated locations were analyzed by histological and immunohistochemical staining. Associations between histology and clinical outcomes were explored.Results: Six months after treatment, it was found that the reticular basement membrane thickness was reduced from 7.28 μm to 5.74 μm (21% relative reduction) and the percentage area of tissue positive for collagen increased from 26.3% to 29.8% (13% relative increase). Collagen structure analysis revealed a reduction in the curvature frequency of fibers. The percentage area positive for fibulin-1 and fibronectin increased by 2.5% and 5.9%, respectively (relative increase of 124% and 15%). No changes were found for elastin. The changes in collagen and fibulin-1 negatively associated with changes in FEV1 reversibility.Conclusions: Besides reduction of airway smooth muscle mass, BT has an impact on reticular basement membrane thickness and the extracellular matrix arrangement characterized by an increase in tissue area occupied by collagen with a less dense fiber organization. Both collagen and fibulin-1 are negatively associated with the change in FEV1 reversibility.</p

Advances in bronchoscopic optical coherence tomography and confocal laser endomicroscopy in pulmonary diseases

Purpose of reviewImaging techniques play a crucial role in the diagnostic work-up of pulmonary diseases but generally lack detailed information on a microscopic level. Optical coherence tomography (OCT) and confocal laser endomicroscopy (CLE) are imaging techniques which provide microscopic images in vivo during bronchoscopy. The purpose of this review is to describe recent advancements in the use of bronchoscopic OCT- and CLE-imaging in pulmonary medicine.Recent findingsIn recent years, OCT- and CLE-imaging have been evaluated in a wide variety of pulmonary diseases and demonstrated to be complementary to bronchoscopy for real-time, near-histological imaging. Several pulmonary compartments were visualized and characteristic patterns for disease were identified. In thoracic malignancy, OCT- and CLE-imaging can provide characterization of malignant tissue with the ability to identify the optimal sampling area. In interstitial lung disease (ILD), fibrotic patterns were detected by both (PS-) OCT and CLE, complementary to current HRCT-imaging. For obstructive lung diseases, (PS-) OCT enables to detect airway wall structures and remodelling, including changes in the airway smooth muscle and extracellular matrix.SummaryBronchoscopic OCT- and CLE-imaging allow high resolution imaging of airways, lung parenchyma, pleura, lung tumours and mediastinal lymph nodes. Although investigational at the moment, promising clinical applications are on the horizon

Airway Inflammation Before and After Bronchial Thermoplasty in Severe Asthma

Background: Bronchial thermoplasty (BT) is a bronchoscopic treatment for severe asthma, of which the working mechanism and responder profile are partly unknown. The aim of this study is to analyse whether BT alters airway inflammation by epithelial gene expression, inflammatory cell counts and cytokines, and whether this relates to treatment response. Methods: In this clinical trial, 28 severe asthma patients underwent bronchoscopy before and after treatment to obtain bronchial brushes and bronchoalveolar lavage fluid (BALF) from treated and untreated airways. RNA was extracted from bronchial brushes for transcriptome analysis, and BALF cells and cytokines were analysed. Asthma quality of life questionnaires were used to distinguish responders from non-responders. We compared results before and after treatment, between treated and untreated airways, and between responders and non-responders. Results: Gene expression of airway epithelium related to airway inflammation gene set was significantly downregulated in treated airways compared to untreated airways, although this did not differ for patients before and after treatment. No differences were observed in cell counts and cytokines, neither from the untreated compared to treated airways, nor before and after treatment. At baseline, compared to non-responders, the expression of genes related to glycolysis in bronchial epithelium was downregulated and both BALF and blood eosinophil counts were higher in responders. Conclusion: Local differences in gene sets pertaining to epithelial inflammatory status were identified between treated and untreated airways after treatment, not resulting in changes in differential cell counts and cytokine analyses in BALF. Secondly, baseline epithelial glycolysis genes and eosinophil counts in BALF and blood were different between responders and non-responders. The observations from this study demonstrate the potential impact of BT on epithelial gene expression related to airway inflammation while also identifying a possible responder profile

Airway Inflammation Before and After Bronchial Thermoplasty in Severe Asthma

BACKGROUND: Bronchial thermoplasty (BT) is a bronchoscopic treatment for severe asthma, of which the working mechanism and responder profile are partly unknown. The aim of this study is to analyse whether BT alters airway inflammation by epithelial gene expression, inflammatory cell counts and cytokines, and whether this relates to treatment response. METHODS: In this clinical trial, 28 severe asthma patients underwent bronchoscopy before and after treatment to obtain bronchial brushes and bronchoalveolar lavage fluid (BALF) from treated and untreated airways. RNA was extracted from bronchial brushes for transcriptome analysis, and BALF cells and cytokines were analysed. Asthma quality of life questionnaires were used to distinguish responders from non-responders. We compared results before and after treatment, between treated and untreated airways, and between responders and non-responders. RESULTS: Gene expression of airway epithelium related to airway inflammation gene set was significantly downregulated in treated airways compared to untreated airways, although this did not differ for patients before and after treatment. No differences were observed in cell counts and cytokines, neither from the untreated compared to treated airways, nor before and after treatment. At baseline, compared to non-responders, the expression of genes related to glycolysis in bronchial epithelium was downregulated and both BALF and blood eosinophil counts were higher in responders. CONCLUSION: Local differences in gene sets pertaining to epithelial inflammatory status were identified between treated and untreated airways after treatment, not resulting in changes in differential cell counts and cytokine analyses in BALF. Secondly, baseline epithelial glycolysis genes and eosinophil counts in BALF and blood were different between responders and non-responders. The observations from this study demonstrate the potential impact of BT on epithelial gene expression related to airway inflammation while also identifying a possible responder profile

Airway inflammation before and after bronchial thermoplasty in severe asthma

BACKGROUND: Bronchial thermoplasty (BT) is a bronchoscopic treatment for severe asthma, of which the working mechanism and responder profile are partly unknown. The aim of this study is to analyse whether BT alters airway inflammation by epithelial gene expression, inflammatory cell counts and cytokines, and whether this relates to treatment response. METHODS: In this clinical trial, 28 severe asthma patients underwent bronchoscopy before and after treatment to obtain bronchial brushes and bronchoalveolar lavage fluid (BALF) from treated and untreated airways. RNA was extracted from bronchial brushes for transcriptome analysis, and BALF cells and cytokines were analysed. Asthma quality of life questionnaires were used to distinguish responders from non-responders. We compared results before and after treatment, between treated and untreated airways, and between responders and non-responders. RESULTS: Gene expression of airway epithelium related to airway inflammation gene set was significantly downregulated in treated airways compared to untreated airways, although this did not differ for patients before and after treatment. No differences were observed in cell counts and cytokines, neither from the untreated compared to treated airways, nor before and after treatment. At baseline, compared to non-responders, the expression of genes related to glycolysis in bronchial epithelium was downregulated and both BALF and blood eosinophil counts were higher in responders. CONCLUSION: Local differences in gene sets pertaining to epithelial inflammatory status were identified between treated and untreated airways after treatment, not resulting in changes in differential cell counts and cytokine analyses in BALF. Secondly, baseline epithelial glycolysis genes and eosinophil counts in BALF and blood were different between responders and non-responders. The observations from this study demonstrate the potential impact of BT on epithelial gene expression related to airway inflammation while also identifying a possible responder profile

Airway Inflammation Before and After Bronchial Thermoplasty in Severe Asthma

Background: Bronchial thermoplasty (BT) is a bronchoscopic treatment for severe asthma, of which the working mechanism and responder profile are partly unknown. The aim of this study is to analyse whether BT alters airway inflammation by epithelial gene expression, inflammatory cell counts and cytokines, and whether this relates to treatment response. Methods: In this clinical trial, 28 severe asthma patients underwent bronchoscopy before and after treatment to obtain bronchial brushes and bronchoalveolar lavage fluid (BALF) from treated and untreated airways. RNA was extracted from bronchial brushes for transcriptome analysis, and BALF cells and cytokines were analysed. Asthma quality of life questionnaires were used to distinguish responders from non-responders. We compared results before and after treatment, between treated and untreated airways, and between responders and non-responders. Results: Gene expression of airway epithelium related to airway inflammation gene set was significantly downregulated in treated airways compared to untreated airways, although this did not differ for patients before and after treatment. No differences were observed in cell counts and cytokines, neither from the untreated compared to treated airways, nor before and after treatment. At baseline, compared to non-responders, the expression of genes related to glycolysis in bronchial epithelium was downregulated and both BALF and blood eosinophil counts were higher in responders. Conclusion: Local differences in gene sets pertaining to epithelial inflammatory status were identified between treated and untreated airways after treatment, not resulting in changes in differential cell counts and cytokine analyses in BALF. Secondly, baseline epithelial glycolysis genes and eosinophil counts in BALF and blood were different between responders and non-responders. The observations from this study demonstrate the potential impact of BT on epithelial gene expression related to airway inflammation while also identifying a possible responder profile