Quantitative assessment of airway remodeling using high-resolution CT

Qualitative and quantitative evaluation of computed tomography changes in adults with cystic fibrosis treated with elexacaftor-tezacaftor-ivacaftor: a retrospective observational study

Introduction: The availability of highly effective triple cystic fibrosis transmembrane conductance regulator (CFTR) modulator combination therapy with elexacaftor-tezacaftor-ivacaftor (ETI) has improved pulmonary outcomes and quality of life of people with cystic fibrosis (pwCF). The aim of this study was to assess computed tomography (CT) changes under ETI visually with the Brody score and quantitatively with dedicated software, and to correlate CT measures with parameters of clinical response. Methods: Twenty two adult pwCF with two consecutive CT scans before and after ETI treatment initiation were retrospectively included. CT was assessed visually employing the Brody score and quantitatively by YACTA, a well-evaluated scientific software computing airway dimensions and lung parenchyma with wall percentage (WP), wall thickness (WT), lumen area (LA), bronchiectasis index (BI), lung volume and mean lung density (MLD) as parameters. Changes in CT metrics were evaluated and the visual and quantitative parameters were correlated with each other and with clinical changes in sweat chloride concentration, spirometry [percent predicted of forced expiratory volume in one second (ppFEV1)] and body mass index (BMI). Results: The mean (SD) Brody score improved with ETI [55 (12) vs. 38 (15); p < 0.001], incl. sub-scores for mucus plugging, peribronchial thickening, and parenchymal changes (all p < 0.001), but not for bronchiectasis (p = 0.281). Quantitatve WP (p < 0.001) and WT (p = 0.004) were reduced, conversely LA increased (p = 0.003), and BI improved (p = 0.012). Lung volume increased (p < 0.001), and MLD decreased (p < 0.001) through a reduction of ground glass opacity areas (p < 0.001). Changes of the Brody score correlated with those of quantitative parameters, exemplarily WT with the sub-score for mucus plugging (r = 0.730, p < 0.001) and peribronchial thickening (r = 0.552, p = 0.008). Changes of CT parameters correlated with those of clinical response parameters, in particular ppFEV1 with the Brody score (r = -0.606, p = 0.003) and with WT (r = -0.538, p = 0.010). Discussion: Morphological treatment response to ETI can be assessed using the Brody score as well as quantitative CT parameters. Changes in CT correlated with clinical improvements. The quantitative analysis with YACTA proved to be an objective, reproducible and simple method for monitoring lung disease, particularly with regard to future interventional clinical trials.

Endobronchial Ultrasound is Useful in the Assessment of Bronchial Wall Changes Related to Bronchial Thermoplasty

Background

Bronchial thermoplasty (BT) is an interventional endoscopic treatment for severe asthma leading to the clinical improvement, but morphologic changes of bronchial wall related to the procedure and predictors of a favorable response to BT remain uncertain. The aim of the study was to validate an endobronchial ultrasound (EBUS) in assessing the effectiveness of BT treatment.

Methods

Patients with severe asthma who met the clinical criteria for BT were included. In all patients clinical data, ACT and AQLQ questionnaires, laboratory tests, pulmonary function tests and bronchoscopy with radial probe EBUS and bronchial biopsies were collected. BT was performed in patients with the thickest bronchial wall L₂ layer representing ASM. These patients were evaluated before and after 12 months of follow-up. The relationship between baseline parameters and clinical response was explored.

Results

Forty patients with severe asthma were enrolled to the study. All 11 patients qualified to BT successfully completed the 3 sessions of bronchoscopy. BT improved asthma control (P=0.006), quality of life (P=0.028) and decreased exacerbation rate (P=0.005). Eight of the 11 patients (72.7%) showed a clinically meaningful improvement. BT also led to a significant decrease in the thicknesses of bronchial wall layers in EBUS (L₁ decreased from 0.183 to 0.173 mm, P=0.003; L₂ from 0.207 to 0.185 mm, P = 0.003; and L_3-5 from 0.969 to 0.886 mm, P=0.003). Median ASM mass decreased by 61.8% (P=0.002). However, there was no association between baseline patient characteristics and the magnitude of clinical improvement after BT.

Conclusion

BT was associated with a significant decrease in the thickness of the bronchial wall layers measured by EBUS including L₂ layer representing ASM and ASM mass reduction in bronchial biopsy. EBUS can assess bronchial structural changes related to BT; however, it did not predict the favorable clinical response to therapy.

Chronic Obstructive Pulmonary Disease and Small Airways Diseases

The small airways are a common target of injury within the lungs and may be affected by a wide variety of inhaled, systemic, and other disorders. Imaging is critical in the detection and diagnosis of small airways disease since significant injury may occur prior to pulmonary function tests showing abnormalities. The goal of this article is to describe the typical imaging findings and patterns of small airways diseases. An approach which divides the imaging appearances into four categories (tree-in-bud opacities, poorly defined centrilobular nodules, mosaic attenuation, and emphysema) will provide a framework in which to formulate appropriate and focused differential diagnoses.

Assessment of Airway Remodeling Using Endobronchial Ultrasound in Asthma-COPD Overlap

PURPOSE

The aim of this study was to evaluate the structural changes of the airways using the endobronchial ultrasound (EBUS) in ACO patients compared to severe asthma and COPD patients.

PATIENTS AND METHODS

The study included 17 patients with ACO, 17 patients with COPD and 33 patients with severe asthma. Detailed clinical data were obtained from all participants. Basic laboratory tests were performed, including measurement of eosinophil counts in blood and serum immunoglobulin E (IgE) concentrations. All patients underwent spirometry and bronchoscopy with EBUS (a 20‑MHz ultrasound probe) to measure the total thicknesses of the bronchial walls and their particular layers in segmental bronchi of the right lower lobe. EBUS allows to distinguish five layers of the bronchial wall. Layer 1 (L1) and layer 2 (L2) were analyzed separately, while the outer layers (layers 3-5 [L3-5]) that correspond to cartilage were assessed together.

RESULTS

In patients with ACO the thicknesses of the L1 and L2 layers, which are mainly responsible for remodeling, were significantly greater than in patients with COPD and significantly smaller than in patients with severe asthma (median L1= 0.17 mm vs 0.16 mm vs 0.18 mm, p<0.001; median L2= 0.18 mm vs 0.17 mm vs 0.20 mm, p<0.001, respectively). The thicknesses of the total bronchial walls (L1+L2+L3-5) and L3-5 were significantly smaller in ACO and COPD patients compared to asthma patients (median L1+L2+L3-5= 1.2 mm vs 1.14 mm vs 1.31 mm, p<0.001; median L3-5= 0.85 mm vs, 0.81 mm vs 0.92 mm, p=0.001, respectively).

CONCLUSION

The process of structural changes in the airways assessed by EBUS is more advanced in individuals with ACO compared to patients with COPD, and less pronounced compared to patients with severe asthma. It seems that EBUS may provide useful information about differences in airway remodeling between ACO, COPD and severe asthma.

Hedgehog interacting protein (HHIP) represses airway remodeling and metabolic reprogramming in COPD-derived airway smooth muscle cells

Although HHIP locus has been consistently associated with the susceptibility to COPD including airway remodeling and emphysema in genome-wide association studies, the molecular mechanism underlying this genetic association remains incompletely understood. By utilizing Hhip+/- mice and primary human airway smooth muscle cells (ASMCs), here we aim to determine whether HHIP haploinsufficiency increases airway smooth muscle mass by reprogramming glucose metabolism, thus contributing to airway remodeling in COPD pathogenesis. The mRNA levels of HHIP were compared in normal and COPD-derived ASMCs. Mitochondrial oxygen consumption rate and lactate levels in the medium were measured in COPD-derived ASMCs with or without HHIP overexpression as readouts of glucose oxidative phosphorylation and aerobic glycolysis rates. The proliferation rate was measured in healthy and COPD-derived ASMCs treated with or without 2-DG. Smooth muscle mass around airways was measured by immunofluorescence staining for α-smooth muscle actin (α-SMA) in lung sections from Hhip+/- mice and their wild type littermates, Hhip+/+ mice. Airway remodeling was assessed in Hhip+/- and Hhip+/- mice exposed to 6 months of cigarette smoke. Our results show HHIP inhibited aerobic glycolysis and represses cell proliferation in COPD-derived ASMCs. Notably, knockdown of HHIP in normal ASMCs increased PKM2 activity. Importantly, Hhip+/- mice demonstrated increased airway remodeling and increased intensity of α-SMA staining around airways compared to Hhip+/+ mice. In conclusion, our findings suggest that HHIP represses aerobic glycolysis and ASMCs hyperplasia, which may contribute to the increased airway remodeling in Hhip+/- mice.

Quantitative CT Analysis of Small Airway Remodeling in Patients with Chronic Obstructive Pulmonary Disease by a New Image Post-Processing System

Purpose

To explore a practical marker for quantitatively analyzing the small airway remodeling in COPD by HRCT.

Patients and Methods

Twenty-four patients with COPD (GOLD I, n = 7; GOLD II, n = 8; GOLD III+IV, n = 9) and 14 healthy controls (7 normal pulmonary function; 7 small-airway disease (SAD)) were enrolled in the study as five groups, GOLD I, GOLD II, GOLD III+IV, normal and SAD. All subjects underwent HRCT and spirometry. With ISP 9.0, whole emphysema index (EI) and the airway parameters, including wall area (WA), lumen area (LA), airway area (AA) of the 3rd, 5th and 9th generations of bronchi, were measured successively. The ratio of LA/AA and WA/AA in the 3rd, 5th and 9th generations of bronchi were calculated and compared among groups.

Results

For the five groups, EI was increased only in GOLD III+IV group (P < 0.05), while the ratio of LA/AA (9-LA/AA) and WA/AA (9-WA/AA) in 9th generation of bronchi have significantly changed since SAD group (P < 0.05). There were significant correlation between FEV₁generations of bronchi (r3 = 0.429, r5 = 0.583, r9 = 0.592, respectively, P < 0.05); FEV₁% and WA/AA (r3 = –0.428, r5 = –0.532, r9 = –0.570, respectively, P < 0.05); as well as MMEF% and LA/AA (r3 = 0.421, r5 = 0.566, r9 = 0.610, respectively, P < 0.05); MMEF% and WA/AA (r3 = –0.421, r5 = –0.529, r9 = –0.593, respectively, P < 0.05).

Conclusion

Small airway remodeling has occurred in the early stage of COPD, while emphysema in the late stage of COPD. The 9-LA/AA and 9-WA/AA are accurate and practical markers for small airway remodeling of COPD.

Pulmonary Ventilation Maps Generated with Free-breathing Proton MRI and a Deep Convolutional Neural Network

Background Hyperpolarized noble gas MRI helps measure lung ventilation, but clinical translation remains limited. Free-breathing proton MRI may help quantify lung function using existing MRI systems without contrast material and may assist in providing information about ventilation not visible to the eye or easily extracted with segmentation methods. Purpose To explore the use of deep convolutional neural networks (DCNNs) to generate synthetic MRI ventilation scans from free-breathing MRI (deep learning [DL] ventilation MRI)-derived specific ventilation maps as a surrogate of noble gas MRI and to validate this approach across a wide range of lung diseases. Materials and Methods In this secondary analysis of prospective trials, 114 paired noble gas MRI and two-dimensional free-breathing MRI scans were obtained in healthy volunteers with no history of chronic or acute respiratory disease and in study participants with a range of different obstructive lung diseases, including asthma, bronchiectasis, chronic obstructive pulmonary disease, and non-small-cell lung cancer between September 2013 and April 2018 (ClinicalTrials.gov identifiers: NCT03169673, NCT02351141, NCT02263794, NCT02282202, NCT02279329, and NCT02002052). A U-Net-based DCNN model was trained to map free-breathing proton MRI to hyperpolarized helium 3 (³He) MRI ventilation and validated using a sixfold validation. During training, the DCNN ventilation maps were compared with noble gas MRI scans using the Pearson correlation coefficient (r) and mean absolute error. DCNN ventilation images were segmented for ventilation and ventilation defects and were compared with noble gas MRI scans using the Dice similarity coefficient (DSC). Relationships were evaluated with the Spearman correlation coefficient (r_S). Results One hundred fourteen study participants (mean age, 56 years ± 15 [standard deviation]; 66 women) were evaluated. As compared with ³He MRI, DCNN model ventilation maps had a mean r value of 0.87 ± 0.08. The mean DSC for DL ventilation MRI and ³He MRI ventilation was 0.91 ± 0.07. The ventilation defect percentage for DL ventilation MRI was highly correlated with ³He MRI ventilation defect percentage (r_S = 0.83, P < .001, mean bias = -2.0% ± 5). Both DL ventilation MRI (r_S = -0.51, P < .001) and ³He MRI (r_S = -0.61, P < .001) ventilation defect percentage were correlated with the forced expiratory volume in 1 second. The DCNN model required approximately 2 hours for training and approximately 1 second to generate a ventilation map. Conclusion In participants with diverse pulmonary pathologic findings, deep convolutional neural networks generated ventilation maps from free-breathing proton MRI trained with a hyperpolarized noble-gas MRI ventilation map data set. The maps showed correlation with noble gas MRI ventilation and pulmonary function measurements. © RSNA, 2020 See also the editorial by Vogel-Claussen in this issue.

Correlation between sestrin2 expression and airway remodeling in COPD

BACKGROUND

Airway remodeling is a major pathological characteristic of chronic obstructive pulmonary disease (COPD), and has been shown to be associated with oxidative stress. Sestrin2 has recently drawn attention as an important antioxidant protein. However, the underlying correlation between sestrin2 and airway remodeling in COPD has yet to be clarified.

METHODS

A total of 124 subjects were enrolled in this study, including 62 control subjects and 62 COPD patients. The pathological changes in airway tissues were assessed by different staining methods. The expression of sestrin2 and matrix metalloproteinase 9 (MMP9) in airway tissues was monitored by immunohistochemistry. Enzyme-linked immunosorbent assays (ELISAs) were used to detect the serum concentrations of sestrin2 and MMP9. The airway parameters on computed tomography (CT) from all participants were measured for evaluating airway remodeling. The relationship between serum sestrin2 and MMP9 concentration and airway parameters in chest CT was also analyzed.

RESULTS

In patients with COPD, staining of airway structures showed distinct pathological changes of remodeling, including cilia cluttered, subepithelial fibrosis, and reticular basement membrane (Rbm) fragmentation. Compared with control subjects, the expression of sestrin2 and MMP9 was significantly increased in both human airway tissues and serum. Typical imaging characteristics of airway remodeling and increased airway parameters were also found by chest CT. Additionally, serum sestrin2 concentration was positively correlated with serum MMP9 concentration and airway parameters in chest CT.

CONCLUSION

Increased expression of sestrin2 is related to airway remodeling in COPD. We demonstrated for the first time that sestrin2 may be a novel biomarker for airway remodeling in patients with COPD.

Variability and Standardization of Quantitative Imaging: Monoparametric to Multiparametric Quantification, Radiomics, and Artificial Intelligence

Radiological images have been assessed qualitatively in most clinical settings by the expert eyes of radiologists and other clinicians. On the other hand, quantification of radiological images has the potential to detect early disease that may be difficult to detect with human eyes, complement or replace biopsy, and provide clear differentiation of disease stage. Further, objective assessment by quantification is a prerequisite of personalized/precision medicine. This review article aims to summarize and discuss how the variability of quantitative values derived from radiological images are induced by a number of factors and how these variabilities are mitigated and standardization of the quantitative values are achieved. We discuss the variabilities of specific biomarkers derived from magnetic resonance imaging and computed tomography, and focus on diffusion-weighted imaging, relaxometry, lung density evaluation, and computer-aided computed tomography volumetry. We also review the sources of variability and current efforts of standardization of the rapidly evolving techniques, which include radiomics and artificial intelligence.

Optimizing airway wall segmentation and quantification by reducing the influence of adjacent vessels and intravascular contrast material with a modified integral-based algorithm in quantitative computed tomography

Introduction

Quantitative analysis of multi-detector computed tomography (MDCT) plays an increasingly important role in assessing airway disease. Depending on the algorithms used, airway dimensions may be over- or underestimated, primarily if contrast material was used. Therefore, we tested a modified integral-based method (IBM) to address this problem.

Methods

Temporally resolved cine-MDCT was performed in seven ventilated pigs in breath-hold during iodinated contrast material (CM) infusion over 60s. Identical slices in non-enhanced (NE), pulmonary-arterial (PA), systemic-arterial (SA), and venous phase (VE) were subjected to an in-house software using a standard and a modified IBM. Total diameter (TD), lumen area (LA), wall area (WA), and wall thickness (WT) were measured for ten extra- and six intrapulmonary airways.

Results

The modified IBM significantly reduced TD by 7.6%, LA by 12.7%, WA by 9.7%, and WT by 3.9% compared to standard IBM on non-enhanced CT (p<0.05). Using standard IBM, CM led to a decrease of all airway parameters compared to NE. For example, LA decreased from 80.85±49.26mm² at NE, to 75.14±47.96mm² (-7.1%) at PA (p<0.001), 74.96±48.55mm² (-7.3%) at SA (p<0.001), and to 78.95±48.94mm² (-2.4%) at VE (p = 0.200). Using modified IBM, the differences were reduced to -3.1% at PA, -2.9% at SA and -0.7% at VE (p<0.001; p<0.001; p = 1.000).

Conclusions

The modified IBM can optimize airway wall segmentation and reduce the influence of CM on quantitative CT. This allows a more precise measurement as well as potentially the comparison of enhanced with non-enhanced scans in inflammatory airway disease.

Airway narrowing and response to simulated deep inspiration in bronchial segments from subjects with fixed airflow obstruction

The volume fraction of extracellular matrix (ECM) within the layer of airway smooth muscle (ASM) is increased in subjects with fixed airflow obstruction. We postulated that changes in ECM within the ASM layer will impact force transmission during induced contraction and/or in response to externally applied stresses like a deep inspiration (DI). Subjects were patients undergoing lung resection surgery who were categorized as unobstructed (n = 12) or "fixed" obstructed (n = 6) on the basis of preoperative spirometry. The response to a DI, assessed by the ratio of isovolumic flows from maximal and partial inspirations (M/P), was also measured preoperatively. M/P was reduced in the obstructed group (P = 0.02). Postoperatively, bronchial segments were obtained from resected tissue, and luminal narrowing to acetylcholine and bronchodilation to simulated DI were assessed in vitro. Airway wall dimensions and the volume fraction of ECM within the ASM were quantified. Maximal airway narrowing to acetylcholine (P = 0.01) and the volume fraction of ECM within the ASM layer (P = 0.02) were increased in the obstructed group, without a change in ASM thickness. Whereas bronchodilation to simulated DI in vitro was not different between obstructed and unobstructed groups, it was correlated with increased M/P (bronchodilation/less bronchoconstriction) in vivo (P = 0.03). The volume fraction of ECM was inversely related to forced expiratory volume in 1 s FEV₁ %predicted (P = 0.04) and M/P (P = 0.01). Results show that in subjects with fixed airflow obstruction the mechanical behavior of the airway wall is altered and there is a contemporaneous shift in the structural composition of the ASM layer.NEW & NOTEWORTHY Cartilaginous airways from subjects with fixed airflow obstruction have an increase in the volume fraction of extracellular matrix within the airway smooth muscle layer. These airways are also intrinsically more reactive to a contractile stimulus, which is expected to contribute to airway hyperresponsiveness in this population, often attributed to geometric mechanisms. In view of these results, we speculate on how changes in extracellular matrix may impact airway mechanics.

Prediction of Treatment Response in Patients with Chronic Obstructive Pulmonary Disease by Determination of Airway Dimensions with Baseline Computed Tomography

Objective

To determine the predictive factors for treatment responsiveness in patients with chronic obstructive pulmonary disease (COPD) at 1-year follow-up by performing quantitative analyses of baseline CT scans.

Materials and Methods

COPD patients (n = 226; 212 men, 14 women) were recruited from the Korean Obstructive Lung Disease cohort. Patients received a combination of inhaled long-acting beta-agonists and corticosteroids twice daily for 3 months and subsequently received medications according to the practicing clinician's decision. The emphysema index, air-trapping indices, and airway parameter (Pi10), calculated using both full-width-half-maximum and integral-based half-band (IBHB) methods, were obtained with baseline CT scans. Clinically meaningful treatment response was defined as an absolute increase of ≥ 0.225 L in the forced expiratory volume in 1 second (FEV₁) at the one-year follow-up. Multivariate logistic regression analysis was performed to investigate the predictors of an increase in FEV₁, and receiver operating characteristic (ROC) analysis was performed to evaluate the performance of the suggested models.

Results

Treatment response was noted in 47 patients (20.8%). The mean FEV₁ increase in responders was 0.36 ± 0.10 L. On univariate analysis, the air-trapping index (ATI) obtained by the subtraction method, ATI of the emphysematous area, and IBHB-measured Pi10 parameter differed significantly between treatment responders and non-responders (p = 0.048, 0.042, and 0.002, respectively). Multivariate analysis revealed that the IBHB-measured Pi10 was the only independent variable predictive of an FEV₁ increase (p = 0.003). The adjusted odds ratio was 1.787 (95% confidence interval: 1.220–2.619). The area under the ROC curve was 0.641.

Conclusion

Measurement of standardized airway dimensions on baseline CT by using a recently validated quantification method can predict treatment responsiveness in COPD patients.

Radiation dose reduction techniques for chest CT: Principles and clinical results

Computer tomography plays a major role in the evaluation of thoracic diseases, especially since the advent of the multidetector-row CT (MDCT) technology. However, the increase use of this technique has raised some concerns about the resulting radiation dose. In this review, we will present the various methods allowing limiting the radiation dose exposure resulting from chest CT acquisitions, including the options of image filtering and iterative reconstruction (IR) algorithms. The clinical applications of reduced dose protocols will be reviewed, especially for lung nodule detection and diagnosis of pulmonary thromboembolism. The performance of reduced dose protocols for infiltrative lung disease assessment will also be discussed. Lastly, the influence of using IR algorithms on computer-aided detection and volumetry of lung nodules, as well as on quantitative and functional assessment of chest diseases will be presented and discussed.

Characterization of tenascin-C as a novel biomarker for asthma: utility of tenascin-C in combination with periostin or immunoglobulin E

Background

Extracellular matrix proteins tenascin-C (TNC) and periostin, which were identified as T-helper cell type 2 cytokine-induced genes in human bronchial epithelial cells, accumulate in the airway basement membrane of asthmatic patients. Although serum periostin has been accepted as a type 2 biomarker, serum TNC has not been evaluated as a systemic biomarker in asthma. Therefore, the objective of this study was to evaluate whether serum TNC can serve as a novel biomarker for asthma.

Methods

We evaluated 126 adult patients with mild to severe asthma. Serum TNC, periostin, and total IgE concentrations were quantified using enzyme-linked immunosorbent assays.

Results

Serum TNC levels were significantly higher in patients with severe asthma and high serum total IgE levels. Patients with both high serum TNC (> 37.16 ng/mL) and high serum periostin (> 95 ng/mL) levels (n = 20) or patients with both high serum TNC and high serum total IgE (> 100 IU/mL) levels (n = 36) presented higher disease severity and more severe airflow limitation than patients in other subpopulations.

Conclusions

To our knowledge, this is the first study to show that serum TNC levels in asthmatic patients are associated with clinical features of asthma and that the combination of serum TNC and periostin levels or combination of serum TNC and total IgE levels were more useful for asthma than each single marker, suggesting that serum TNC can serve as a novel biomarker for asthma.

Electronic supplementary material

The online version of this article (10.1186/s13223-018-0300-7) contains supplementary material, which is available to authorized users.

Emphysematous and Nonemphysematous Gas Trapping in Chronic Obstructive Pulmonary Disease: Quantitative CT Findings and Pulmonary Function

Purpose To identify a prevalent computed tomography (CT) subtype in patients with chronic obstructive pulmonary disease (COPD) by separating emphysematous from nonemphysematous contributions to total gas trapping and to attempt to predict and grade the emphysematous gas trapping by using clinical and functional data. Materials and Methods Two-hundred and two consecutive eligible patients (159 men and 43 women; mean age, 70 years [age range, 41-85 years]) were prospectively studied. Pulmonary function and CT data were acquired by pulmonologists and radiologists. Noncontrast agent-enhanced thoracic CT scans were acquired at full inspiration and expiration, and were quantitatively analyzed by using two software programs. CT parameters were set as follows: 120 kVp; 200 mAs; rotation time, 0.5 second; pitch, 1.1; section thickness, 0.75 mm; and reconstruction kernels, b31f and b70f. Gas trapping obtained by difference of inspiratory and expiratory CT density thresholds (percentage area with CT attenuation values less than -950 HU at inspiration and percentage area with CT attenuation values less than -856 HU at expiration) was compared with that obtained by coregistration analysis. A logistic regression model on the basis of anthropometric and functional data was cross-validated and trained to classify patients with COPD according to the relative contribution of emphysema to total gas trapping, as assessed at CT. Results Gas trapping obtained by difference of inspiratory and expiratory CT density thresholds was highly correlated (r = 0.99) with that obtained by coregistration analysis. Four groups of patients were distinguished according to the prevalent CT subtype: prevalent emphysematous gas trapping, prevalent functional gas trapping, mixed severe, and mixed mild. The predictive model included predicted forced expiratory volume in 1 second/vital capacity, percentage of predicted forced expiratory volume in 1 second, percentage of diffusing capacity for carbon monoxide, and body mass index as emphysema regressors at CT, with 81% overall accuracy in classifying patients according to its extent. Conclusion The relative contribution of emphysematous and nonemphysematous gas trapping obtained by coregistration of inspiratory and expiratory CT scanning can be determined accurately by difference of CT inspiratory and expiratory density thresholds. CT extent of emphysema can be predicted with accuracy suitable for clinical purposes by pulmonary function data and body mass index. ^© RSNA, 2018 Online supplemental material is available for this article.

Involvement of c-Jun N-Terminal Kinase in TNF-α-Driven Remodeling

Lung tissue remodeling in chronic obstructive pulmonary disease (COPD) is characterized by airway wall thickening and/or emphysema. Although the bronchial and alveolar compartments are functionally independent entities, we recently showed comparable alterations in matrix composition comprised of decreased elastin content and increased collagen and hyaluronan contents of alveolar and small airway walls. Out of several animal models tested, surfactant protein C (SPC)-TNF-α mice showed remodeling in alveolar and airway walls similar to what we observed in patients with COPD. Epithelial cells are able to undergo a phenotypic shift, gaining mesenchymal properties, a process in which c-Jun N-terminal kinase (JNK) signaling is involved. Therefore, we hypothesized that TNF-α induces JNK-dependent epithelial plasticity, which contributes to lung matrix remodeling. To this end, the ability of TNF-α to induce a phenotypic shift was assessed in A549, BEAS2B, and primary bronchial epithelial cells, and phenotypic markers were studied in SPC-TNF-α mice. Phenotypic markers of mesenchymal cells were elevated both in vitro and in vivo, as shown by the expression of vimentin, plasminogen activator inhibitor-1, collagen, and matrix metalloproteinases. Concurrently, the expression of the epithelial markers, E-cadherin and keratin 7 and 18, was attenuated. A pharmacological inhibitor of JNK attenuated this phenotypic shift in vitro, demonstrating involvement of JNK signaling in this process. Interestingly, activation of JNK signaling was also clearly present in lungs of SPC-TNF-α mice and patients with COPD. Together, these data show a role for TNF-α in the induction of a phenotypic shift in vitro, resulting in increased collagen production and the expression of elastin-degrading matrix metalloproteinases, and provide evidence for involvement of the TNF-α-JNK axis in extracellular matrix remodeling.

Phenotyping Before Starting Treatment in COPD?

Chronic Obstructive Pulmonary Disease (COPD) is a heterogeneous and complex disease with great morbidity and mortality. Despite the new developments in the managements of COPD, it was recognized that not all patients benefit from the available medications. Therefore, efforts to identify subgroups or phenotypes had been made in order to predict who will respond to a class of drugs for COPD. This review will discuss phenotypes, endotypes, and subgroups such as the frequent exacerbator, the one with systemic inflammation, the fast decliner, ACOS, and the one with co-morbidities and their impact on therapy. It became apparent, that the "inflammatory" phenotypes: frequent exacerbator, chronic bronchitic, and those with a number of co-morbidities need inhaled corticosteroids; in contrast, the emphysematous type with dyspnea and lung hyperinflation, the fast decliner, need dual bronchodilation (deflators). However, larger, well designed studies clustering COPD patients are needed, in order to identify the important subgroups and thus, to lead to personalize management in COPD.

Phenotyping emphysema and airways disease: Clinical value of quantitative radiological techniques

The pathophysiology of chronic obstructive pulmonary disease (COPD) and Alpha one antitrypsin deficiency is increasingly recognised as complex such that lung function alone is insufficient for early detection, clinical categorisation and dictating management. Quantitative imaging techniques can detect disease earlier and more accurately, and provide an objective tool to help phenotype patients into predominant airways disease or emphysema. Computed tomography provides detailed information relating to structural and anatomical changes seen in COPD, and magnetic resonance imaging/nuclear imaging gives functional and regional information with regards to ventilation and perfusion. It is likely imaging will become part of routine clinical practice, and an understanding of the implications of the data is essential. This review discusses technical and clinical aspects of quantitative imaging in obstructive airways disease.

Management of COPD: Is there a role for quantitative imaging?

While the recent development of quantitative imaging methods have led to their increased use in the diagnosis and management of many chronic diseases, medical imaging still plays a limited role in the management of chronic obstructive pulmonary disease (COPD). In this review we highlight three pulmonary imaging modalities: computed tomography (CT), magnetic resonance imaging (MRI) and optical coherence tomography (OCT) imaging and the COPD biomarkers that may be helpful for managing COPD patients. We discussed the current role imaging plays in COPD management as well as the potential role quantitative imaging will play by identifying imaging phenotypes to enable more effective COPD management and improved outcomes.

CT Scan Does Not Differentiate Patients with Hepatopulmonary Syndrome from Other Patients with Liver Disease

Background

Hepatopulmonary syndrome (HPS) is defined by liver dysfunction, intrapulmonary vascular dilatations, and impaired oxygenation. The gold standard for detection of intrapulmonary vascular dilatations in HPS is contrast echocardiography. However, two small studies have suggested that patients with HPS have larger segmental pulmonary arterial diameters than both normal subjects and normoxemic subjects with cirrhosis, when measured by CT. We sought to compare CT imaging-based pulmonary vasodilatation in patients with HPS, patients with liver dysfunction without HPS, and matching controls on CT imaging.

Methods

We performed a retrospective cohort study at two quaternary care Canadian HPS centers. We analyzed CT thorax scans in 23 patients with HPS, 29 patients with liver dysfunction without HPS, and 52 gender- and age-matched controls. We measured the artery-bronchus ratios (ABRs) in upper and lower lung zones, calculated the “delta ABR” by subtracting the upper from the lower ABR, compared these measurements between groups, and correlated them with clinically relevant parameters (partial pressure of arterial oxygen, alveolar-arterial oxygen gradient, macroaggregated albumin shunt fraction, and diffusion capacity). We repeated measurements in patients with post-transplant CTs.

Results

Patients had significantly larger lower zone ABRs and delta ABRs than controls (1.20 +/- 0.19 versus 0.98 +/- 0.10, p<0.01; and 0.12 +/- 0.17 versus -0.06 +/- 0.10, p<0.01, respectively). However, there were no significant differences between liver disease patients with and without HPS, nor any significant correlations between CT measurements and clinically relevant parameters. There were no significant changes in ABRs after liver transplantation (14 patients).

Conclusions

Basilar segmental artery-bronchus ratios are larger in patients with liver disease than in normal controls, but this vasodilatation is no more severe in patients with HPS. CT does not distinguish patients with HPS from those with uncomplicated liver disease.

Airway remodelling in COPD: It's not asthma!

COPD is defined as airflow limitation that is not reversed by treatment. In asthma, airflow limitation is not only reversible, but also inducible. This is called 'airway hyperresponsiveness' (AHR) and is associated with thickening of the airway wall, predominantly the layer of airway smooth muscle, due to more cells, bigger cells and more extracellular matrix (ECM) in proportion to the increase in smooth muscle. AHR is also observed in COPD if the changes in airflow are expressed as a percent of the baseline lung function. However, the absolute change in baseline lung function that can be induced in COPD is actually less than that seen in normal subjects, suggesting that the airways in COPD are resistant not only to opening, but also to closing. This observation agrees with physiological measures showing increased airway wall stiffness in COPD. Like asthma, airway wall thickness is increased in COPD, including the layer of smooth muscle. Unlike asthma, however, fixed airflow obstruction appears to be characterized by a disproportionate increase in the ECM within the smooth muscle layer. In this review, we summarize the studies of airway matrix deposition in COPD and put forward the proposal that the airway remodelling in COPD is different from that in asthma and call for a systematic analysis of airway matrix deposition in COPD.

A mixed phenotype of airway wall thickening and emphysema is associated with dyspnea and hospitalization for chronic obstructive pulmonary disease

RATIONALE

Quantitative computed tomography (CT) has been used to phenotype patients with chronic obstructive pulmonary disease (COPD). A mixed phenotype is defined as the presence of both airway wall thickening and emphysema on quantitative CT. Little is known about patients with COPD with the mixed phenotype.

OBJECTIVES

To propose a method of phenotyping COPD based on quantitative CT and to compare clinically relevant outcomes between patients with COPD with the mixed phenotype and those with other CT-based phenotypes.

METHODS

Each of 427 male smokers (187 without COPD, 240 with COPD) underwent a complete medical interview, pulmonary function testing, and whole-lung CT on the same day. The percentage of low-attenuation volume at the threshold of -950 Hounsfield units (%LAV) and the square root of wall area of a hypothetical airway with an internal perimeter of 10 mm (Pi10) were measured. Patients with COPD were classified into four distinct phenotypes based on the upper limits of normal for %LAV and Pi10, which were derived from the data of smokers without COPD by using quantile regression.

MEASUREMENTS AND MAIN RESULTS

Of 240 patients with COPD, 52 (21.7%) were classified as CT-normal phenotype, 39 (16.3%) as airway-dominant phenotype, 103 (42.9%) as emphysema-dominant phenotype, and 46 (19.2%) as mixed phenotype. Patients with COPD with the mixed phenotype were associated with more severe dyspnea than those with each of the remaining CT-based phenotypes (P < 0.01 for all comparisons). The number of hospitalizations for COPD exacerbations during the preceding year was 2.0 to 3.6 times higher in patients with the mixed phenotype than in those with each of the remaining CT-based phenotypes (P < 0.05 for all comparisons). Findings persisted after adjustment for age, pack-years of smoking, smoking status, body mass index, and FEV1.

CONCLUSIONS

Patients with COPD with the mixed phenotype are associated with more severe dyspnea and more frequent hospitalizations than those with each of the remaining CT-based phenotypes. Thus, patients with COPD with the mixed phenotype may need more attention and interventions.

Increased Epicardial Adipose Tissue Is Associated with the Airway Dominant Phenotype of Chronic Obstructive Pulmonary Disease

Background

Epicardial adipose tissue (EAT) has been shown to be a non-invasive marker that predicts the progression of cardiovascular disease (CVD). It has been reported that the EAT volume is increased in patients with chronic obstructive pulmonary disease (COPD). However, little is known about which phenotypes of COPD are associated with increased EAT.

Methods

One hundred and eighty smokers who were referred to the clinic were consecutively enrolled. A chest CT was used for the quantification of the emphysematous lesions, airway lesions, and EAT. These lesions were assessed as the percentage of low attenuation volume (LAV%), the square root of airway wall area of a hypothetical airway with an internal perimeter of 10 mm (√Aaw at Pi10) and the EAT area, respectively. The same measurements were made on 225 Vietnamese COPD patients to replicate the results.

Results

Twenty-six of the referred patients did not have COPD, while 105 were diagnosed as having COPD based on a FEV₁/FVC<0.70. The EAT area was significantly associated with age, BMI, FEV₁ (%predicted), FEV₁/FVC, self-reported hypertension, self-reported CVD, statin use, LAV%, and √Aaw at Pi10 in COPD patients. The multiple regression analyses showed that only BMI, self-reported CVD and √Aaw at Pi10 were independently associated with the EAT area (R² = 0.51, p<0.0001). These results were replicated in the Vietnamese population.

Conclusions

The EAT area is independently associated with airway wall thickness. Because EAT is also an independent predictor of CVD risk, these data suggest a mechanistic link between the airway predominant form of COPD and CVD.

Childhood asthma and chronic obstructive pulmonary disease: outcomes until the age of 50

PURPOSE OF REVIEW

There has been recent interest in understanding the origins of chronic obstructive pulmonary disease. Epidemiological studies suggest that chronic obstructive pulmonary disease clearly has other causes apart from tobacco smoke.

RECENT FINDINGS

Cross-sectional studies of adult cohorts with chronic obstructive pulmonary disease highlight that childhood asthma is a risk factor. A recent longitudinal childhood cohort study of children from childhood to the age of 50 years describes that children with severe asthma are at increased risk of chronic obstructive pulmonary disease and that the deficit in lung function can be tracked back to early years.

SUMMARY

Children with severe asthma are at increased risk of developing chronic obstructive pulmonary disease.

Monitoring inflammation and airway remodeling by fluorescence molecular tomography in a chronic asthma model

BACKGROUND

Asthma is a multifactorial disease for which a variety of mouse models have been developed. A major drawback of these models is represented by the transient nature of the airway pathology peaking 24-72 h after challenge and resolving in 1-2 weeks. We characterized the temporal evolution of pulmonary inflammation and tissue remodeling in a recently described mouse model of chronic asthma (8 week treatment with 3 allergens: Dust mite, Ragweed, and Aspergillus; DRA).

METHODS

We studied the DRA model taking advantage of fluorescence molecular tomography (FMT) imaging using near-infrared probes to non-invasively evaluate lung inflammation and airway remodeling. At 4, 6, 8 or 11 weeks, cathepsin- and metalloproteinase-dependent fluorescence was evaluated in vivo. A subgroup of animals, after 4 weeks of DRA, was treated with Budesonide (100 µg/kg intranasally) daily for 4 weeks.

RESULTS

Cathepsin-dependent fluorescence in DRA-sensitized mice resulted significantly increased at 6 and 8 weeks, and was markedly inhibited by budesonide. This fluorescent signal well correlated with ex vivo analysis such as bronchoalveolar lavage eosinophils and pulmonary inflammatory cell infiltration. Metalloproteinase-dependent fluorescence was significantly increased at 8 and 11 weeks, nicely correlated with collagen deposition, as evaluated histologically by Masson's Trichrome staining, and airway epithelium hypertrophy, and was only partly inhibited by budesonide.

CONCLUSIONS

FMT proved suitable for longitudinal studies to evaluate asthma progression, showing that cathepsin activity could be used to monitor inflammatory cell infiltration while metalloproteinase activity parallels airway remodeling, allowing the determination of steroid treatment efficacy in a chronic asthma model in mice.

The effect of asthma on the perimeter of the airway basement membrane

When comparing the pathology of airways in individuals with and without asthma, the perimeter of the basement membrane (Pbm) is used as a marker of airway size, as it is independent of airway smooth muscle shortening or airway collapse. The extent to which the Pbm is itself altered in asthma has not been quantified. The aim of this study was to compare the Pbm from the same anatomical sites in postmortem lungs from subjects with (n = 55) and without (n = 30) asthma (nonfatal or fatal). Large and small airways were systematically sampled at equidistant "levels" from the apical segment of the left upper lobes and anterior and basal segments of the left lower lobes of lungs fixed in inflation. The length of the Pbm was estimated from cross sections of airway at each relative level. Linear mixed models were used to investigate the relationships between Pbm and sex, age, height, smoking status, airway level, and asthma group. The final model showed significant interactions between Pbm and airway level in small (<3 mm) airways, in subjects having asthma (P < 0.0001), and by sex (P < 0.0001). No significant interactions for Pbm between asthma groups were observed for larger airways (equivalent to a diameter of ∼3 mm and greater) or smoking status. Asthma is not associated with remodeling of the Pbm in large airways. In medium and small airways, the decrease in Pbm in asthma (≤20%) would not account for the published differences in wall area or area of smooth muscle observed in cases of severe asthma.

Optical coherence tomography in respiratory science and medicine: from airways to alveoli

Optical coherence tomography is a rapidly maturing optical imaging technology, enabling study of the in vivo structure of lung tissue at a scale of tens of micrometers. It has been used to assess the layered structure of airway walls, quantify both airway lumen caliber and compliance, and image individual alveoli. This article provides an overview of the technology and reviews its capability to provide new insights into respiratory disease.

Variation in the percent of emphysema-like lung in a healthy, nonsmoking multiethnic sample. The MESA lung study

RATIONALE

Computed tomography (CT)-based lung density is used to quantitate the percentage of emphysema-like lung (hereafter referred to as percent emphysema), but information on its distribution among healthy nonsmokers is limited.

OBJECTIVES

We evaluated percent emphysema and total lung volume on CT scans of healthy never-smokers in a multiethnic, population-based study.

METHODS

The Multi-Ethnic Study of Atherosclerosis (MESA) Lung Study investigators acquired full-lung CT scans of 3,137 participants (ages 54-93 yr) between 2010-12. The CT scans were taken at full inspiration following the Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS) protocol. "Healthy never-smokers" were defined as participants without a history of tobacco smoking or respiratory symptoms and disease. "Percent emphysema" was defined as the percentage of lung voxels below -950 Hounsfield units. "Total lung volume" was defined by the volume of lung voxels.

MEASUREMENTS AND MAIN RESULTS

Among 854 healthy never-smokers, the median percent emphysema visualized on full-lung scans was 1.1% (interquartile range, 0.5-2.5%). The percent emphysema values were 1.2 percentage points higher among men compared with women and 0.7, 1.2, and 1.2 percentage points lower among African Americans, Hispanics, and Asians compared with whites, respectively (P < 0.001). Percent emphysema was positively related to age and height and inversely related to body mass index. The findings were similar for total lung volume on CT scans and for percent emphysema defined at -910 Hounsfield units and measured on cardiac scans. Reference equations to account for these differences are presented for never, former and current smokers.

CONCLUSIONS

Similar to lung function, percent emphysema varies substantially by demographic factors and body size among healthy never-smokers. The presented reference equations will assist in defining abnormal values for percent emphysema and total lung volume on CT scans, although validation is pending.

TWEAK enhances TGF-β-induced epithelial-mesenchymal transition in human bronchial epithelial cells

BACKGROUND

Chronic airway inflammatory disorders, such as asthma, are characterized by airway inflammation and remodeling. Chronic inflammation and damage to the airway epithelium cause airway remodeling, which is associated with improper epithelial repair, and is characterized by elevated expression of transforming growth factor-β (TGF-β). Epithelial-mesenchymal transition (EMT) is an important mechanism during embryonic development and tissue remodeling whereby epithelial cells gain the capacity to increase motility by down-regulation of epithelial markers and up-regulation of mesenchymal markers. TGF-β is a central inducer of EMT, and TGF-β-induced EMT is enhanced by pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α) and interleukin-1β. We investigated whether the pro-inflammatory cytokine TWEAK (TNF-like weak inducer of apoptosis) enhanced TGF-β1-induced EMT in the human bronchial epithelial cell line BEAS-2B.

METHODS

Quantitative RT-PCR and western blotting were used to define alterations in epithelial and mesenchymal marker expression in BEAS-2B cells. The cells were assessed for 48 h after stimulation with TGF-β1 alone or in combination with TWEAK.

RESULTS

TGF-β1 induced spindle-like morphology and loss of cell contact, and reduced the expression of epithelial marker E-cadherin and increased the expression of mesenchymal markers N-cadherin and vimentin. Our data, for the first time, show that TWEAK reduced the expression of E-cadherin, and that co-treatment with TGF-β1 and TWEAK enhanced the TGF-β1-induced features of EMT. Moreover, hyaluronan synthase 2 expression was up-regulated by a combination with TGF-β1 and TWEAK, but not TNF-α. We also demonstrated that the Smad, p38 MAPK, and NF-κB signaling pathways, and the transcriptional repressor ZEB2 might mediate N-cadherin up-regulation by TGF-β1 in combination with TWEAK.

CONCLUSIONS

These findings suggest that the pro-inflammatory cytokine TWEAK and TGF-β1 have synergistic effects in EMT and may contribute to chronic airway changes and remodeling.

Free-breathing pulmonary 1H and Hyperpolarized 3He MRI: comparison in COPD and bronchiectasis

RATIONALE AND OBJECTIVES

In this proof-of-concept demonstration, we aimed to quantitatively and qualitatively compare pulmonary ventilation abnormalities derived from Fourier decomposition of free-breathing (1)H magnetic resonance imaging (FDMRI) to hyperpolarized (3)He MRI in subjects with chronic obstructive pulmonary disease (COPD) and bronchiectasis.

MATERIALS AND METHODS

All subjects provided written informed consent to a protocol approved by a local research ethics board and Health, Canada, and they underwent MRI, computed tomography (CT), spirometry, and plethysmography during a single 2-hour visit. Semiautomated segmentation was used to generate ventilation defect measurements derived from FDMRI and (3)He MRI, and these were compared using analysis of variance and Pearson correlations.

RESULTS

Twenty-six subjects were evaluated including 12 COPD subjects (67 ± 9 years) and 14 bronchiectasis subjects (70 ± 11 years). For COPD subjects, FDMRI and (3)He MRI ventilation defect percent (VDP) was 7 ± 6% and 24 ± 14%, respectively (P < .001; bias = -16 ± 9%). In COPD subjects, FDMRI was significantly correlated with (3)He MRI VDP (r = .88; P = .0001), (3)He MRI apparent diffusion coefficient (r = .71; P < .05), airways resistance (r = .60; P < .05), and RA950 (r = .80; P < .01). In subjects with bronchiectasis, FDMRI VDP (5 ± 3%) and (3)He MRI VDP (18 ± 9%) were significantly different (P < .001) and not correlated (P > .05). The Dice similarity coefficient (DSC) for FDMRI and (3)He MRI ventilation was 86 ± 7% for COPD and 86 ± 4% for bronchiectasis subjects (P > .05); the DSC for FDMRI ventilation defects and CT RA950 was 19 ± 20% in COPD and 2 ± 3% in bronchiectasis subjects (P < .01).

CONCLUSIONS

FDMRI and (3)He MRI VDP were strongly related in COPD but not in bronchiectasis subjects. In COPD only, FDMRI ventilation defects were spatially related with (3)He ventilation defects and emphysema.

Persistent severe hypereosinophilic asthma is not associated with airway remodeling

Hypereosinophilic asthma (HEA) is considered as a specific severe asthma phenotype. Whether eosinophils have a link with airway remodeling characterized by pathological (thickening of the basement membrane), functional (persistent airflow impairment and decline in lung function) and imaging features (increase airway wall thickness at CT scan) is still debated. In a one year prospective cohort of 142 severe asthma patients (according to IMI), 14 persistent HEA patients (defined by a persistent blood eosinophilia >500/mm(3) at two consecutive visits) were identified and compared with ten patients without any blood eosinophilia during the follow-up period (NEA, blood eosinophilia always <500/mm(3)). Airflow and lung volumes were recorded. Bronchial biopsies obtained at enrollment were stained for eosinophils (EG2) and basement membrane thickness (BM) was quantified. Imaging by CT scan acquisition was standardized and bronchial abnormalities quantified. ACQ score and exacerbations were prospectively recorded. HEA was not associated with preeminent features of airway remodeling assessed by airflow impairment (Best ever FEV1 values 97% ± 20 in HEA vs. 80 ± 24% in NEA, p = 0.020), decline of FEV1 (FEV1 Decline 40 ± 235 ml/y in HEA vs. 19 ± 40 ml/y in NEA, P = 0.319), submucosal abnormalities (BM thickness 7.80 ± 2.66 μm in HEA vs. 6.84 ± 2.59 in NEA, p = 0.37) and airway wall thickening at CT-scan (0.250 ± 0.036 mm vs. 0.261 ± 0.043, p = 0.92). Eosinophils blood count was inversely correlated with semiquantitative imaging score (rho -0.373, p = 0.039). Smoking history and positive skin prick tests were independent risk factors for increased BM thickening. Outcomes were similar in both populations (Control and exacerbations). Persistent HEA is not associated with evidences of airway remodeling.

Cigarette smoke extract induces a phenotypic shift in epithelial cells; involvement of HIF1α in mesenchymal transition

In COPD, matrix remodeling contributes to airflow limitation. Recent evidence suggests that next to fibroblasts, the process of epithelial-mesenchymal transition can contribute to matrix remodeling. CSE has been shown to induce EMT in lung epithelial cells, but the signaling mechanisms involved are largely unknown and subject of this study. EMT was assessed in A549 and BEAS2B cells stimulated with CSE by qPCR, Western blotting and immunofluorescence for epithelial and mesenchymal markers, as were collagen production, cell adhesion and barrier integrity as functional endpoints. Involvement of TGF-β and HIF1α signaling pathways were investigated. In addition, mouse models were used to examine the effects of CS on hypoxia signaling and of hypoxia per se on mesenchymal expression. CSE induced EMT characteristics in A549 and BEAS2B cells, evidenced by decreased expression of epithelial markers and a concomitant increase in mesenchymal marker expression after CSE exposure. Furthermore cells that underwent EMT showed increased production of collagen, decreased adhesion and disrupted barrier integrity. The induction of EMT was found to be independent of TGF-β signaling. On the contrary, CS was able to induce hypoxic signaling in A549 and BEAS2B cells as well as in mice lung tissue. Importantly, HIF1α knock-down prevented induction of mesenchymal markers, increased collagen production and decreased adhesion after CSE exposure, data that are in line with the observed induction of mesenchymal marker expression by hypoxia in vitro and in vivo. Together these data provide evidence that both bronchial and alveolar epithelial cells undergo a functional phenotypic shift in response to CSE exposure which can contribute to increased collagen deposition in COPD lungs. Moreover, HIF1α signaling appears to play an important role in this process.

A comparative study of matrix remodeling in chronic models for COPD; mechanistic insights into the role of TNF-α

Remodeling in chronic obstructive pulmonary disease (COPD) has at least two dimensions: small airway wall thickening and destruction of alveolar walls. Recently we showed comparable alterations of the extracellular matrix (ECM) compounds collagen, hyaluoran, and elastin in alveolar and small airway walls of COPD patients. The aim of this study was to characterize and assess similarities in alveolar and small airway wall matrix remodeling in chronic COPD models. From this comparative characterization of matrix remodeling we derived and elaborated underlying mechanisms to the matrix changes reported in COPD. Lung tissue sections of chronic models for COPD, either induced by exposure to cigarette smoke, chronic intratracheal lipopolysaccharide instillation, or local tumor necrosis factor (TNF) expression [surfactant protein C (SPC)-TNFα mice], were stained for elastin, collagen, and hyaluronan. Furthermore TNF-α matrix metalloproteinase (MMP)-2, -9, and -12 mRNA expression was analyzed using qPCR and localized using immunohistochemistry. Both collagen and hyaluronan were increased in alveolar and small airway walls of all three models. Interestingly, elastin contents were differentially affected, with a decrease in both alveolar and airway walls in SPC-TNFα mice. Furthermore TNF-α and MMP-2 and -9 mRNA and protein levels were found to be increased in alveolar walls and around airway walls only in SPC-TNFα mice. We show that only SPC-TNFα mice show changes in elastin remodeling that are comparable to what has been observed in COPD patients. This reveals that the SPC-TNFα model is a suitable model to study processes underlying matrix remodeling and in particular elastin breakdown as seen in COPD. Furthermore we indicate a possible role for MMP-2 and MMP-9 in the breakdown of elastin in airways and alveoli of SPC-TNFα mice.

Plasma cytokine profiles related to smoking-sensitivity and phenotypes of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) develops only in smoking-sensitive smokers and manifests heterogeneous phenotypes, including emphysema and non-emphysema types. We aimed to identify biomarkers related to the smoking-sensitivity and phenotypes of COPD. Among 240 smokers suggestive of COPD, we studied on four groups defined by % forced expiratory volume in one second (FEV1) and computed tomography-based pulmonary emphysema. Plasma concentrations of 33 inflammatory markers were measured in four groups as well as Non-smokers using multiplex protein arrays. IL-5, IL-7 and IL-13 were identified to be associated with smoking sensitivity and IL-6 and IL-10 were candidate biomarkers for airway-lesion dominant COPD.

Bronchial wall measurements in patients after lung transplantation: evaluation of the diagnostic value for the diagnosis of bronchiolitis obliterans syndrome

OBJECTIVES

To prospectively evaluate quantitative airway wall measurements of thin-section CT for the diagnosis of Bronchiolitis Obliterans Syndrome (BOS) following lung transplantation.

MATERIALS AND METHODS

In 141 CT examinations, bronchial wall thickness (WT), the wall area percentage (WA%) calculated as the ratio of the bronchial wall area and the total area (sum of bronchial wall area and bronchial lumen area) and the difference of the WT on inspiration and expiration (WTdiff) were automatically measured in different bronchial generations. The measurements were correlated with the lung function parameters. WT and WA% in CT examinations of patients with (n = 25) and without (n = 116) BOS, were compared using the unpaired t-test and univariate analysis of variance, while also considering the differing lung volumes.

RESULTS

Measurements could be performed in 2,978 bronchial generations. WT, WA%, and WTdiff did not correlate with the lung function parameters (r<0.5). The WA% on inspiration was significantly greater in patients with BOS than in patients without BOS, even when considering the dependency of the lung volume on the measurements. WT on inspiration and expiration and WA% on expiration did not show significant differences between the groups.

CONCLUSION

WA% on inspiration was significantly greater in patients with than in those without BOS. However, WA% measurements were significantly dependent on lung volume and showed a high variability, thus not allowing the sole use of bronchial wall measurements to differentiate patients with from those without BOS.

Quantitative computed tomography-derived clusters: redefining airway remodeling in asthmatic patients

BACKGROUND

Asthma heterogeneity is multidimensional and requires additional tools to unravel its complexity. Computed tomography (CT)-assessed proximal airway remodeling and air trapping in asthmatic patients might provide new insights into underlying disease mechanisms.

OBJECTIVES

The aim of this study was to explore novel, quantitative, CT-determined asthma phenotypes.

METHODS

Sixty-five asthmatic patients and 30 healthy subjects underwent detailed clinical, physiologic characterization and quantitative CT analysis. Factor and cluster analysis techniques were used to determine 3 novel, quantitative, CT-based asthma phenotypes.

RESULTS

Patients with severe and mild-to-moderate asthma demonstrated smaller mean right upper lobe apical segmental bronchus (RB1) lumen volume (LV) in comparison with healthy control subjects (272.3 mm(3) [SD, 112.6 mm(3)], 259.0 mm(3) [SD, 53.3 mm(3)], 366.4 mm(3) [SD, 195.3 mm(3)], respectively; P = .007) but no difference in RB1 wall volume (WV). Air trapping measured based on mean lung density expiratory/inspiratory ratio was greater in patients with severe and mild-to-moderate asthma compared with that seen in healthy control subjects (0.861 [SD, 0.05)], 0.866 [SD, 0.07], and 0.830 [SD, 0.06], respectively; P = .04). The fractal dimension of the segmented airway tree was less in asthmatic patients compared with that seen in control subjects (P = .007). Three novel, quantitative, CT-based asthma clusters were identified, all of which demonstrated air trapping. Cluster 1 demonstrates increased RB1 WV and RB1 LV but decreased RB1 percentage WV. On the contrary, cluster 3 subjects have the smallest RB1 WV and LV values but the highest RB1 percentage WV values. There is a lack of proximal airway remodeling in cluster 2 subjects.

CONCLUSIONS

Quantitative CT analysis provides a new perspective in asthma phenotyping, which might prove useful in patient selection for novel therapies.

Chronic obstructive pulmonary disease: lobe-based visual assessment of volumetric CT by Using standard images--comparison with quantitative CT and pulmonary function test in the COPDGene study

PURPOSE

To provide a new detailed visual assessment scheme of computed tomography (CT) for chronic obstructive pulmonary disease (COPD) by using standard reference images and to compare this visual assessment method with quantitative CT and several physiologic parameters.

MATERIALS AND METHODS

This research was approved by the institutional review board of each institution. CT images of 200 participants in the COPDGene study were evaluated. Four thoracic radiologists performed independent, lobar analysis of volumetric CT images for type (centrilobular, panlobular, and mixed) and extent (on a six-point scale) of emphysema, the presence of bronchiectasis, airway wall thickening, and tracheal abnormalities. Standard images for each finding, generated by two radiologists, were used for reference. The extent of emphysema, airway wall thickening, and luminal area were quantified at the lobar level by using commercial software. Spearman rank test and simple and multiple regression analyses were performed to compare the results of visual assessment with physiologic and quantitative parameters.

RESULTS

The type of emphysema, determined by four readers, showed good agreement (κ = 0.63). The extent of the emphysema in each lobe showed good agreement (mean weighted κ = 0.70) and correlated with findings at quantitative CT (r = 0.75), forced expiratory volume in 1 second (FEV(1)) (r = -0.68), FEV(1)/forced vital capacity (FVC) ratio (r = -0.74) (P < .001). Agreement for airway wall thickening was fair (mean κ = 0.41), and the number of lobes with thickened bronchial walls correlated with FEV(1) (r = -0.60) and FEV(1)/FVC ratio (r = -0.60) (P < .001).

CONCLUSION

Visual assessment of emphysema and airways disease in individuals with COPD can provide reproducible, physiologically substantial information that may complement that provided by quantitative CT assessment.

Nicotine-induced epithelial-mesenchymal transition via Wnt/β-catenin signaling in human airway epithelial cells

Epithelial-mesenchymal transition (EMT) has been proposed to be a mechanism in airway remodeling, which is a characteristic of chronic obstructive pulmonary disease (COPD). Studies have shown that cigarette smoke and nicotine are factors that induce Wnt/β-catenin activation, which is a pathway that has also been implicated in EMT. The main aim of this study was to test whether human bronchial epithelial cells are able to undergo EMT in vitro following nicotine stimulation via the Wnt3a/β-catenin signaling pathway. We show that nicotine activates the Wnt3a signal pathway, which leads to the translocation of β-catenin into the nucleus and activation of β-catenin/Tcf-dependent transcription in the human bronchial epithelial cell (HBEC) line. This accumulation was accompanied by an increase in smooth muscle actin, vimentin, matrix metalloproteinases-9, and type I collagen expression as well as downregulation of E-cadherin, which are typical characteristics of EMT. We also noted that the release of TGF-β(1) from these cells was stimulated by nicotine. Knockdown of Wnt3a with small interfering RNA (siRNA) prevented these effects, implying that β-catenin activation in these responses is Wnt3a dependent. Furthermore, specific knockdown of TGF-β(1) with TGF-β(1) siRNA partially prevented nicotine-induced EMT, suggesting that TGF-β(1) has a role in nicotine-mediated EMT in HBECs. These results suggest that HBECs are able to undergo EMT in vitro upon nicotine stimulation via the Wnt3a/β-catenin signaling pathway.

Static and dynamic imaging of alveoli using optical coherence tomography needle probes

Imaging of alveoli in situ has for the most part been infeasible due to the high resolution required to discern individual alveoli and limited access to alveoli beneath the lung surface. In this study, we present a novel technique to image alveoli using optical coherence tomography (OCT). We propose the use of OCT needle probes, where the distal imaging probe has been miniaturized and encased within a hypodermic needle (as small as 30-gauge, outer diameter 310 μm), allowing insertion deep within the lung tissue with minimal tissue distortion. Such probes enable imaging at a resolution of ∼12 μm within a three-dimensional cylindrical field of view with diameter ∼1.5 mm centered on the needle tip. The imaging technique is demonstrated on excised lungs from three different species: adult rats, fetal sheep, and adult pigs. OCT needle probes were used to image alveoli, small bronchioles, and blood vessels, and results were matched to histological sections. We also present the first dynamic OCT images acquired with an OCT needle probe, allowing tracking of individual alveoli during simulated cyclical lung inflation and deflation.