Reticular Basement Membrane Thickness Research Articles

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

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. We sought to investigate the effect of BT on extracellular matrix composition and its association with clinical outcomes. 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. 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. 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.

Baseline reticular basement membrane morphology is related to subsequent spirometry deterioration in pediatric chronic airway inflammation: a follow-up study.

Reticular basement membrane (RBM) thickening may occur in children with allergic bronchial asthma (BA), cystic fibrosis (CF), and primary ciliary dyskinesia (PCD). Its functional consequences remain unknown. We investigated the relationship between baseline RBM thickness and subsequent spirometry. In our cohort follow-up study, patients aged 3-18 yr with BA, CF, and PCD and controls underwent baseline lung clearance index (LCI) measurement, spirometry, and endobronchial biopsy sampling. Total RBM and collagen IV-positive layer thickness were measured. Trends in forced vital capacity (FVC), forced expired volume in 1 s (FEV1), and FEV1/FVC were analyzed during follow-up, and their relationship to baseline characteristics was studied using univariate analysis and multiple regression models. Complete baseline data were available in 19 patients with BA, 30 patients with CF, 25 patients with PCD, and 19 controls. The RBM was thicker in patients with BA (6.33 ± 1.22 μm), CF (5.60 ± 1.39 μm), and PCD (6.50 ± 1.87 μm) than in controls (3.29 ± 0.55 μm) (all P < 0.001). The LCI was higher in patients with CF (15.32 ± 4.58, P < 0.001) and PCD (10.97 ± 2.46, P = 0.002) than in controls (7.44 ± 0.43). The median follow-up times were 3.6, 4.8, 5.7, and 1.9 years in patients with BA, CF, PCD, and controls, respectively. The z-scores of FEV1 and FEV1/FVC deteriorated significantly in all groups except in controls. In patients with CF and PCD, trends in FEV1 z-scores correlated with baseline LCI and RBM; in BA, it correlated with collagen IV. In multiple regression models, RBM morphology and ventilation inhomogeneity could predict up to 84.4% of variability in spirometry trends. In conclusion, baseline LCI value and RBM morphology may predict trends in subsequent spirometry.NEW & NOTEWORTHY This paper deals with the relationship between reticular basement membrane (RBM) morphology at baseline and follow-up spirometry in children with asthma, cystic fibrosis, and primary ciliary dyskinesia. For the first time, to our knowledge, the possibility to predict subsequent lung function development using selected baseline characteristics (reticular basement membrane morphology from endobronchial biopsy and ventilation inhomogeneity from nitrogen multiple breath washout test) is proposed. Corresponding predictive models are presented.

Effect of Calycosin on Airway Inflammation and Airway Remodeling in Allergic Asthma Mouse Model

Background: This study aimed to construct a TDI-induced mouse model of asthma, and evaluate the potential effects and possible molecular mechanisms of Calycosin on airway inflammation and airway remodeling in mouse model. Material and methods: ELISA method was applied to detect the total serum IgE level and the inflammatory cytokine level in the bronchoalveolar lavage fluid. The total number of cells and the proportion of inflammatory cells in BALF were evaluated under an optical microscope. HE was employed to assess and score the infiltration of peritracheal and perivascular inflammatory cells in lung tissue, and PAS staining was used to assess the proportion of goblet cells in the airway epithelium and the thickness of airway epithelial reticular basement membrane in each group of mice. WB was used to detect the expressions of HMGB1 and a-SMA in cells. Immunofluorescence staining was used to detect the expressions of HMGB1 and a-SMA in 16HBEs. Results: The airway hyperresponsiveness of the Calycosin TDI asthma mice decreased, the inflammatory factors in BALF and the total serum IgE levels decreased, the airway epithelial goblet cell metaplasia and the thickness of the airway epithelial reticular basement membrane were improved, thus reducing the up-regulation of HMGB1 and a-SMA expression of 16HBES induced by TDI-HSA. Conclusion: In our study, in the TDI-induced mouse model of asthma, the administration of drug to inhibit the activation of AKT can reduce airway inflammation and airway remodeling. These findings have enriched the current understanding of Calycosin and provided a basis for future research. However, there are also some limitations: How does TDI activate the AKT signaling pathway? After the activation of the AKT pathway, the mechanism by which the expressions of HMGB1, α-SMA and Collagen-I were up-regulated has not been fully elucidated.

Co-Expression Analysis of Airway Epithelial Transcriptome in Asthma Patients with Eosinophilic vs. Non-Eosinophilic Airway Infiltration.

Asthma heterogeneity complicates the search for targeted treatment against airway inflammation and remodeling. We sought to investigate relations between eosinophilic inflammation, a phenotypic feature frequent in severe asthma, bronchial epithelial transcriptome, and functional and structural measures of airway remodeling. We compared epithelial gene expression, spirometry, airway cross-sectional geometry (computed tomography), reticular basement membrane thickness (histology), and blood and bronchoalveolar lavage (BAL) cytokines of n = 40 moderate to severe eosinophilic (EA) and non-eosinophilic asthma (NEA) patients distinguished by BAL eosinophilia. EA patients showed a similar extent of airway remodeling as NEA but had an increased expression of genes involved in the immune response and inflammation (e.g., KIR3DS1), reactive oxygen species generation (GYS2, ATPIF1), cell activation and proliferation (ANK3), cargo transporting (RAB4B, CPLX2), and tissue remodeling (FBLN1, SOX14, GSN), and a lower expression of genes involved in epithelial integrity (e.g., GJB1) and histone acetylation (SIN3A). Genes co-expressed in EA were involved in antiviral responses (e.g., ATP1B1), cell migration (EPS8L1, STOML3), cell adhesion (RAPH1), epithelial-mesenchymal transition (ASB3), and airway hyperreactivity and remodeling (FBN3, RECK), and several were linked to asthma in genome- (e.g., MRPL14, ASB3) or epigenome-wide association studies (CLC, GPI, SSCRB4, STRN4). Signaling pathways inferred from the co-expression pattern were associated with airway remodeling (e.g., TGF-β/Smad2/3, E2F/Rb, and Wnt/β-catenin).

Relationships between Airway Remodeling and Clinical Characteristics in COPD Patients.

Background: Airway remodeling is a cardinal feature of chronic obstructive pulmonary disease (COPD) pathology. However, inconsistent findings have been reported regarding the nature of proximal airway remodeling in COPD. This is likely due to the heterogeneity of COPD. This study investigated the histopathological features of airway remodeling in bronchial biopsies of COPD patients compared to smoking controls (S). We tested the hypothesis that histopathological features in bronchial biopsies relate to clinical characteristics in COPD patients, focusing on smoking status, symptom burden, lung function, exacerbation risk and inhaled corticosteroid (ICS) use. Methods: We recruited 24 COPD patients and 10 S. We focused on reticular basement membrane thickness (RBM), surface immunoglobulin A (IgA) expression, goblet cell numbers (periodic acid-Schiff [PAS]+), sub-mucosal remodeling markers including collagen 4, 6 and laminin expression, and inflammatory cell counts (CD45+). Results: RBM thickness was increased in frequent exacerbators, IgA expression was reduced in COPD patients with worse lung function, and goblet cell numbers were increased in COPD patients compared to S but with no difference between the COPD subgroups. Collagen 4 expression was associated with higher symptom burden and worse quality of life. Sub-mucosal inflammatory cell counts were increased in COPD non-inhaled corticosteroid (ICS) users compared to ICS users and S. Conclusion: We observed relationships between the histopathological features of airway remodeling and clinical characteristics in COPD patients. Our data highlight the influence of clinical heterogeneity on diverse patterns of airway remodeling in COPD patients.

Pathogenesis, clinical features of asthma COPD overlap, and therapeutic modalities.

Both asthma and COPD are heterogeneous diseases identified by characteristic symptoms and functional abnormalities, with airway obstruction common in both diseases. Asthma COPD overlap (ACO) does not define a single disease but is a descriptive term for clinical use that includes several overlapping clinical phenotypes of chronic airways disease with different underlying mechanisms. This literature review was initiated to describe published studies, identify gaps in knowledge, and propose future research goals regarding the disease pathology of ACO, especially the airway remodeling changes and inflammation aspects. Airway remodeling occurs in asthma and COPD, but there are differences in the structures affected and the prime anatomic site at which they occur. Reticular basement membrane thickening and cellular infiltration with eosinophils and T-helper (CD4+) lymphocytes are prominent features of asthma. Epithelial squamous metaplasia, airway wall fibrosis, emphysema, bronchoalveolar lavage (BAL) neutrophilia, and (CD8+) T-cytotoxic lymphocyte infiltrations in the airway wall are features of COPD. There is no universally accepted definition of ACO, nor are there clearly defined pathological characteristics to differentiate from asthma and COPD. Understanding etiological concepts within the purview of inflammation and airway remodeling changes in ACO would allow better management of these patients.

Effect of tezepelumab on airway inflammatory cells, remodelling, and hyperresponsiveness in patients with moderate-to-severe uncontrolled asthma (CASCADE): a double-blind, randomised, placebo-controlled, phase 2 trial

Tezepelumab is a human monoclonal antibody that blocks the activity of thymic stromal lymphopoietin (TSLP), an epithelial cell-derived cytokine. In phase 2b and 3 studies, tezepelumab significantly reduced exacerbations versus placebo in patients with severe uncontrolled asthma, irrespective of baseline levels of type 2 inflammatory biomarkers. We investigated the mechanism of action of tezepelumab by assessing its effects on airway inflammatory cells, airway remodelling, and airway hyperresponsiveness. CASCADE was an exploratory, double-blind, randomised, placebo-controlled, parallel-group, phase 2 study done in 27 medical centres in Canada, Denmark, Germany, the UK, and the USA. Adults aged 18-75 years with uncontrolled, moderate-to-severe asthma were randomly assigned (1:1) to receive tezepelumab 210 mg or placebo administered subcutaneously every 4 weeks for a planned 28 weeks, extended to up to 52 weeks if COVID-19-related disruption delayed participants' end-of-treatment assessments. Randomisation was balanced and stratified by blood eosinophil count. The primary endpoint was the change from baseline to the end of treatment in the number of airway submucosal inflammatory cells in bronchoscopic biopsy samples. Eosinophils, neutrophils, CD3+ T cells, CD4+ T cells, tryptase+ mast cells, and chymase+ mast cells were evaluated separately. This endpoint was also assessed in subgroups according to baseline type 2 inflammatory biomarker levels, including blood eosinophil count. Airway remodelling was assessed via the secondary endpoints of change from baseline in reticular basement membrane thickness and epithelial integrity (proportions of denuded, damaged, and intact epithelium). Exploratory outcomes included airway hyperresponsiveness to mannitol. All participants who completed at least 20 weeks of study treatment, had an end-of-treatment visit up to 8 weeks after the last dose of study drug, and had evaluable baseline and end-of-treatment bronchoscopies were included in the primary efficacy analysis. All participants who received at least one dose of study drug were included in the safety analyses. This study is registered with ClinicalTrials.gov, NCT03688074. Between Nov 2, 2018, and Nov 16, 2020, 250 patients were enrolled, 116 of whom were randomly assigned (59 to tezepelumab, 57 to placebo). 48 in the tezepelumab group and 51 in the placebo group completed the study and were assessed for the primary endpoint. Treatment with tezepelumab resulted in a nominally significantly greater reduction from baseline to the end of treatment in airway submucosal eosinophils versus placebo (ratio of geometric least-squares means 0·15 [95% CI 0·05-0·41]; nominal p<0·0010), with the difference seen across all baseline biomarker subgroups. There were no significant differences between treatment groups in the other cell types evaluated (ratio of geometric least-squares means: neutrophils 1·36 [95% CI 0·94-1·97]; CD3+ T cells 1·12 [0·86-1·46]; CD4+ T cells 1·18 [0·90-1·55]; tryptase+ mast cells 0·83 [0·61-1·15]; chymase+ mast cells 1·19 [0·67-2·10]; all p>0·10). In assessment of secondary endpoints, there were no significant differences between treatment groups in reticular basement membrane thickness and epithelial integrity. In an exploratory analysis, the reduction in airway hyperresponsiveness to mannitol was significantly greater with tezepelumab versus placebo (least-squares mean change from baseline in interpolated or extrapolated provoking dose of mannitol required to induce ≥15% reduction in FEV1 from baseline: tezepelumab 197·4 mg [95% CI 107·9 to 286·9]; placebo 58·6 mg [-30·1 to 147·33]; difference 138·8 [14·2 to 263·3], nominal p=0·030). Adverse events were reported in 53 (90%) patients in the tezepelumab group and 51 (90%) patients in the placebo group, and there were no safety findings of concern. The improvements in asthma clinical outcomes observed in previous studies with tezepelumab are probably driven, at least in part, by reductions in eosinophilic airway inflammation, as shown here by reduced airway eosinophil counts regardless of baseline blood eosinophil count. Tezepelumab also reduced airway hyperresponsiveness to mannitol, indicating that TSLP blockade might have additional benefits in asthma beyond reducing type 2 airway inflammation. AstraZeneca and Amgen.

Interactions via α2β1 Cell Integrin May Protect against the Progression of Airway Structural Changes in Asthma.

Increased airway wall thickness and remodeling of bronchial mucosa are characteristic of asthma and may arise from altered integrin signaling on airway cells. Here, we analyzed the expression of β1-subfamily integrins on blood and airway cells (flow cytometry), inflammatory biomarkers in serum and bronchoalveolar lavage, reticular basement membrane (RBM) thickness and collagen deposits in the mucosa (histology), and airway geometry (CT-imaging) in 92 asthma patients (persistent airflow limitation subtype: n = 47) and 36 controls. Persistent airflow limitation was associated with type-2 inflammation, elevated soluble α2 integrin chain, and changes in the bronchial wall geometry. Both subtypes of asthma showed thicker RBM than control, but collagen deposition and epithelial α1 and α2 integrins staining were similar. Type-I collagen accumulation and RBM thickness were inversely related to the epithelial expression of the α2 integrin chain. Expression of α2β1 integrin on T-cells and eosinophils was not altered in asthma. Collagen I deposits were, however, more abundant in patients with lower α2β1 integrin on blood and airway CD8+ T-cells. Thicker airway walls in CT were associated with lower α2 integrin chain on blood CD4+ T-cells and airway eosinophils. Our data suggest that α2β1 integrin on inflammatory and epithelial cells may protect against airway remodeling advancement in asthma.

Effect of omalizumab on bronchoalveolar lavage matrix metalloproteinases in severe allergic asthma

Introduction Airway inflammation in asthma is accompanied by reconstruction of the bronchial wall extracellular matrix that most likely occurs with a contribution of matrix metalloproteinases (MMPs). Recently we have reported that omalizumab may decrease reticular basement membrane (RBM) thickness together with fibronectin deposits in asthmatic airways, although mechanisms involved are unknown. Objective In the present study, we have investigated the impact of omalizumab on MMPs concentrations in bronchoalveolar lavage fluid (BAL) of asthmatic subjects in relation to airway remodeling changes in histology. Patients and methods The study group consisted of 13 severe allergic asthmatics treated with omalizumab for at least 12 months. In each subject, clinical and laboratory parameters, bronchoscopy with BAL, and endobronchial biopsy were evaluated before and after the biologic therapy. RBM thickness, fibronectin, and collagen deposits in bronchial mucosa specimens were analyzed in histology. The investigations also included BAL cytology and BAL concentrations of MMP-2, −3, and −9. Results Omalizumab was related to a decrease in all measured MMPs in BAL (p < 0.001, each), although such declines were not observed in each patient. The depletions were associated with a lower asthma exacerbation rate and better asthma control. Interestingly, patients who showed a decline in at least one MMP (n = 10, 77%) were characterized by a higher decrease in the RBM thickness (–1.61 [–2.02 to −0.6] vs. −0.06 [–0.09 to +3.3], p = 0.03). Likewise, individuals with lower concentrations of MMP-9 after omalizumab (n = 7, 58%) had a greater reduction in the RBM layer as compared to those with steady MMP-9 levels (–1.8 [–2.4 to −1.14] vs. −0.13 [–0.6 to −0.06] μm, p = 0.03). Moreover, the latter group also had unfavorable higher collagen I accumulation after biologic (42 [20 to 55] vs. 0 [–10 to 20]%, respectively, p = 0.03). Higher concentrations of MMPs in BAL at baseline were related to the lower systemic steroid dose and better omalizumab response concerning the decline in RBM thickness. Conclusion Our data suggest that omalizumab therapy is associated with decreased BAL MMPs concentration in the subgroup of asthma patients. The decline was linked with a reduction in the RBM thickness what might play a beneficial role in airway remodeling.

Reticular Basement Membrane Thickness Is Associated with Growth- and Fibrosis-Promoting Airway Transcriptome Profile-Study in Asthma Patients.

Airway remodeling in asthma is characterized by reticular basement membrane (RBM) thickening, likely related to epithelial structural and functional changes. Gene expression profiling of the airway epithelium might identify genes involved in bronchial structural alterations. We analyzed bronchial wall geometry (computed tomography (CT)), RBM thickness (histology), and the bronchial epithelium transcriptome profile (gene expression array) in moderate to severe persistent (n = 21) vs. no persistent (n = 19) airflow limitation asthmatics. RBM thickness was similar in the two studied subgroups. Among the genes associated with increased RBM thickness, the most essential were those engaged in cell activation, proliferation, and growth (e.g., CDK20, TACC2, ORC5, and NEK5) and inhibiting apoptosis (e.g., higher mRNA expression of RFN34, BIRC3, NAA16, and lower of RNF13, MRPL37, CACNA1G). Additionally, RBM thickness correlated with the expression of genes encoding extracellular matrix (ECM) components (LAMA3, USH2A), involved in ECM remodeling (LTBP1), neovascularization (FGD5, HPRT1), nerve functioning (TPH1, PCDHGC4), oxidative stress adaptation (RIT1, HSP90AB1), epigenetic modifications (OLMALINC, DNMT3A), and the innate immune response (STAP1, OAS2). Cluster analysis revealed that genes linked with RBM thickness were also related to thicker bronchial walls in CT. Our study suggests that the pro-fibrotic profile in the airway epithelial cell transcriptome is associated with a thicker RBM, and thus, may contribute to asthma airway remodeling.

Repetitive nasal allergen challenge in allergic rhinitis: Priming and Th2-type inflammation but no evidence of remodelling.

Local tissue eosinophilia and Th2 cytokines are characteristic features of seasonal allergic rhinitis. Airway remodelling is a feature of asthma whereas evidence for remodelling in allergic rhinitis (AR) is conflicting. By use of a novel human repetitive nasal allergen challenge (RAC) model, we evaluated the relationship between allergic inflammation and features of remodelling in AR. Twelve patients with moderate-severe AR underwent 5 alternate day challenges with diluent which after 4weeks were followed by 5 alternate day challenges with grass pollen extract. Nasal symptoms, Th1/Th2 cytokines in nasal secretion and serum were evaluated. Nasal biopsies were taken 24hours after the 1st and 5th challenges with diluent and with allergen. Sixteen healthy controls underwent a single challenge with diluent and with allergen. Using immunohistochemistry, epithelial and submucosal inflammatory cells and remodelling markers were evaluated by computed image analysis. There was an increase in early and late-phase symptoms after every allergen challenge compared to diluent (both P<.05) with evidence of both clinical and immunological priming. Nasal tissue eosinophils and IL-5 in nasal secretion increased significantly after RAC compared to corresponding diluent challenges (P<.01, P=.01, respectively). There was a correlation between submucosal mast cells and the early-phase clinical response (r=0.79, P=.007) and an association between epithelial eosinophils and IL-5 concentrations in nasal secretion (r=0.69, P=.06) in allergic rhinitis. No differences were observed after RAC with regard to epithelial integrity, reticular basement membrane thickness, glandular area, expression of markers of activation of airway remodelling including α-SMA, HSP-47, extracellular matrix (MMP7, 9 and TIMP-1), angiogenesis and lymphangiogenesis for AR compared with healthy controls. Novel repetitive nasal allergen challenge in participants with severe persistent seasonal allergic rhinitis resulted in tissue eosinophilia and increases in IL-5 but no structural changes. Our data support no link between robust Th2-inflammation and development of airway remodelling in AR.

CASCADE: a phase 2, randomized, double-blind, placebo-controlled, parallel-group trial to evaluate the effect of tezepelumab on airway inflammation in patients with uncontrolled asthma

BackgroundPatients with severe, uncontrolled asthma, particularly those with a non-eosinophilic phenotype, have a great unmet need for new treatments that act on a broad range of inflammatory pathways in the airway. Tezepelumab is a human monoclonal antibody that blocks the activity of thymic stromal lymphopoietin, an epithelial cytokine. In the PATHWAY phase 2b study (NCT02054130), tezepelumab reduced exacerbations by up to 71% in adults with severe, uncontrolled asthma, irrespective of baseline eosinophilic inflammatory status. This article reports the design and objectives of the phase 2 CASCADE study.MethodsCASCADE is an ongoing exploratory, phase 2, randomized, double-blind, placebo-controlled, parallel-group study aiming to assess the anti-inflammatory effects of tezepelumab 210 mg administered subcutaneously every 4 weeks for 28 weeks in adults aged 18–75 years with uncontrolled, moderate-to-severe asthma. The primary endpoint is the change from baseline to week 28 in airway submucosal inflammatory cells (eosinophils, neutrophils, T cells and mast cells) from bronchoscopic biopsies. Epithelial molecular phenotyping, comprising the three-gene-mean technique, will be used to assess participants’ type 2 (T2) status to enable evaluation of the anti-inflammatory effect of tezepelumab across the continuum of T2 activation. Other exploratory analyses include assessments of the impact of tezepelumab on airway remodelling, including reticular basement membrane thickening and airway epithelial integrity. At the onset of the COVID-19 pandemic, the protocol was amended to address the possibility that site visits would be limited. The amendment allowed for: at-home dosing of study drug by a healthcare professional, extension of the treatment period by up to 6 months so patients are able to attend an onsite visit to undergo the end-of-treatment bronchoscopy, and replacement of final follow-up visits with a virtual or telephone visit.DiscussionCASCADE aims to determine the mechanisms by which tezepelumab improves clinical asthma outcomes by evaluating the effect of tezepelumab on airway inflammatory cells and remodelling in patients with moderate-to-severe, uncontrolled asthma. An important aspect of this study is the evaluation of the anti-inflammatory effect of tezepelumab across patients with differing levels of eosinophilic and T2 inflammation.Trial registrationNCT03688074 (ClinicalTrials.gov). Registered 28 September 2018.

Histopathological Comparison of Endobronchial Biopsies from Different Pulmonary Lobes of Severe Asthmatic Patients

Histopathological Comparison of Endobronchial Biopsies from Different Pulmonary Lobes of Severe Asthmatic Patients

Diagnostic Value of Serum Long-Chain Noncoding RNA KCNQ1OT1 in Airway Remodeling in Children with Bronchial Asthma.

The current study aims to investigate the clinical value of serum long non-coding RNA (lncRNA) KCNQ1OT1 in airway remodeling in children with bronchial asthma. Serum and clinical data of 58 children with bronchial asthma were collected and divided into remodeling group and non-remodeling group. Twenty children with respiratory inflammatory diseases were selected as a control group. Real-time fluorescence quantitative PCR (RT-PCR) was used to detect the expression of serum lnc-RNA KCNQ1OT1. The relationship between serum lncRNA KCNQ1OT1 and asthma remodeling was also analyzed. The expression level of serum lncRNA KCNQ1OT1 in the remodeling group was higher than that in the non-remodeling group and the control group, and the difference was statistically significant. In the remodeling group, serum lncRNA KCNQ1OT1 was significantly correlated with the thickness of bronchial mucosal reticular basement membrane and the number of fibroblasts. Receiver operating characteristic curve (ROC) analysis showed that serum lncRNA KCNQ1OT1 could differentiate non-remodeling group from remodeling group. Serum lncRNA KCNQ1OT1 can predict the occurrence of airway remodeling in children with bronchial asthma, thereby initiating early intervention and treatment of airway inflammation.

Ventilation Inhomogeneity and Bronchial Basement Membrane Changes in Chronic Neutrophilic Airway Inflammation

Bronchial epithelial reticular basement membrane (RBM) thickening occurs in diseases with both eosinophilic (allergic bronchial asthma [BA]) and neutrophilic (cystic fibrosis [CF] and primary ciliary dyskinesia [PCD]) chronic airway inflammation; however, the lung function and airway remodeling relation remains unclear. The aim of this study was to test whether ventilation inhomogeneity is related to RBM thickening. Multiple breath washout test, endobronchial biopsy, and BAL were performed in 24 children with CF, 11 with PCD, 15 with BA, and in 19 control subjects. Lung clearance index at 2.5%(1/40th) of starting nitrogen concentration (LCI2.5), RBM thickness, and lavage fluid cytology were quantified; their mutual associations were studied by using Spearman rank correlations (r). In asthma, ventilation inhomogeneity (mean ± SD) was mild (LCI2.5, 9.3 ± 1.4 vs7.9 ± 0.9 in control subjects; P= .0391), and the RBM thickened (5.26 ± 0.98 μm vs3.12 ± 0.62 μm in control subjects; P< .0001). No relation between RBM thickness and ventilation inhomogeneity or lavage cytology was found. In CF and PCD, RBM thickness was similar to that in asthma (4.54 ± 0.66 μm and 5.27 ± 1.11 μm, respectively), but ventilation inhomogeneity was significantly higher (LCI2.5, 12.5 ± 2.4 and 11.8 ± 2.5). Both in CF and PCD, RBM thickness correlated with LCI2.5 (r= 0.594, P= .015; r= 0.821, P= .023). In PCD only, RBM thickness was also related to the number of neutrophils in lavage fluid (r= 0.821; P= .023). Lung function impairment in relation to RBM thickness was milder in BA than in CF and PCD. In asthma, ventilation inhomogeneity did not correlate with RBM thickness, whereas it did in CF and PCD. This outcome suggests a different structure-function relation in these diseases.

The relationship of airway structural changes to blood and bronchoalveolar lavage biomarkers, and lung function abnormalities in asthma.

Airway structural changes are important in asthma pathology and require further investigations. We sought to evaluate which computed tomography (CT) indices, bronchial histological traits, or blood and bronchoalveolar lavage (BAL) biomarkers correlate best with lung function abnormalities in asthma. In 105 white adult asthmatics (53 with a component of fixed airflow obstruction), we determined airway cross-sectional geometry of two proximal (the right upper lobe apical segmental and the left apicoposterior) and two distal (the right and the left basal posterior) bronchi, quantified the low-attenuation lung area (LAA%), and analysed clusters based on airway CT-metrics. We also performed bronchofiberoscopy with BAL and endobronchial biopsy, assessed blood and BAL biomarkers, including interleukin (IL)-4, IL-5, IL-6, IL-10, IL-12p70, IL-17A, IL-23, interferon (INF)γ and periostin, together with circulating a disintegrin and metalloproteinase domain-containing protein (ADAM)33, and investigated interplays between analysed variables. Patients with fixed airflow limitation were characterized by lower lumen area and increased wall area and wall thickness ratios in distal airways, accompanied by raised LAA%. They had also higher blood neutrophilia, blood and BAL eosinophilia, increased circulating fibrinogen, periostin, and ADAM33. Blood neutrophilia, serum high density lipoproteins, thyroid-stimulating hormone, and shortened activated partial thromboplastin time were determinants of thicker reticular basement membrane (RBM). BAL eosinophilia was the only positive predictor of collagen I accumulation. Surprisingly, we observed a negative correlation between RBM thickening and collagen I deposit. Cluster analysis based on CT-metrics of the right lower lobe basal posterior bronchus revealed three well-separated clusters similar in age, asthma duration, and BMI, but different in RBM thickness, collagen I accumulation, and inflammatory markers. Airway remodelling traits are mainly related to the Th2 profile, higher circulating ADAM33, and blood neutrophilia. Lung function abnormalities and RBM thickening correlate better with CT-metrics of distal than proximal airways.

Endobronchial biopsy in the final diagnosis of chronic obstructive pulmonary disease and asthma: a clinicopathological study.

BACKGROUNDAsthma and chronic obstructive pulmonary disease (COPD) are chronic conditions with an increasing prevalence in developing countries. The evaluation of endobronchial biopsies has emerged as a tool to differentiate between both conditions via the measurement of the reticular basement membrane (RBM) thickness with various conclusions drawn from different studies.OBJECTIVESCompare the thickness of the RBM between asthma and COPD and evaluate other histomorphological features in both groups.DESIGNProspective, descriptive and analytical.SETTINGUniversity teaching hospital.PATIENTS AND METHODSThe study included patients with COPD and irreversible and reversible asthma with diagnosis based on clinical assessment, pulmonary function tests and high-resolution computed tomography scans. Endobronchial biopsies were obtained from all patients and, using a light microscope and a computerized image analyzer, the thickness of the reticular basement membrane was calculated in all patients. We also made a qualitative assessment of other histomorphological features.MAIN OUTCOME MEASURESMean RBM thickness.SAMPLE SIZEThirty male patients.RESULTSThe mean RBM thickness in asthmatic patients was 8.9 (2.4) μm. The mean RBM thickness in COPD patients was 5.3 (1.1) μm. However, there was no thickening of the RBM in patients with reversible asthma. The RBM was significantly thicker in patients with irreversible asthma than in patients with COPD or reversible asthma. There were no significant differences in epithelial desquamation or metaplasia, mucosal or submucosal inflammation, the presence of eosinophils, submucosal glandular hyperplasia or submucosal smooth muscle hyperplasia between groups.CONCLUSIONSThe thickness of the RBM is the only reproducible histopathological feature to differentiate COPD from irreversible asthma.LIMITATIONSThe study included a limited number of patients. A qualitative approach was used to compare epithelial cell injury, inflammation, submucosal glandular and muscular hyperplasia.

The role of bone marrow-derived endothelial progenitor cells and angiogenic responses in chronic obstructive pulmonary disease.

Increased vascularity of the bronchial sub-mucosa is a cardinal feature of chronic obstructive pulmonary disease (COPD) and is associated with disease severity. Capillary engorgement, leakage, and vasodilatation can directly increase airway wall thickness resulting in airway luminal narrowing and facilitate inflammatory cell trafficking, thereby contributing to irreversible airflow obstruction, a characteristic of COPD. Airway wall neovascularisation, seen as increases in both the size and number of bronchial blood vessels is a prominent feature of COPD that correlates with reticular basement membrane thickening and airway obstruction. Sub-epithelial vascularization may be an important remodelling event for airway narrowing and airflow obstruction in COPD. Post-natal angiogenesis is a complex process, whereby new blood vessels sprouting from extant microvasculature, can arise from the proliferation of resident mature vascular endothelial cells (ECs). In addition, this may arise from increased turnover and lung-homing of circulating endothelial progenitor cells (EPCs) from the bone marrow (BM). Following lung-homing, EPCs can differentiate locally within the tissue into ECs, further contributing to vascular repair, maintenance, and expansion under pathological conditions, governed by a locally elaborated milieu of growth factors (GFs). In this article, we will review evidence for the role of BM-derived EPCs in the development of angiogenesis in the lug and discuss how this may relate to the pathogenesis of COPD.

Increased neutrophil gelatinase-associated lipocalin (NGAL) promotes airway remodelling in chronic obstructive pulmonary disease

Airway remodelling is an important component of chronic obstructive pulmonary disease (COPD). Neutrophil gelatinase-associated lipocalin (NGAL) from neutrophils may drive COPD epithelial-mesenchymal transition (EMT). NGAL expression was quantified in the lungs of COPD patients and bronchoalveolar lavage fluid (BALF) of ozone-treated mice. Reticular basement membrane (RBM) thickness and E-cadherin and α-smooth muscle actin (α-SMA) expression were determined in mice airways. Effects of cigarette smoke extract (CSE) and inflammatory factors on NGAL expression in human neutrophils as well as the effects of NGAL on airway structural cells was assessed. NGAL was mainly distributed in neutrophils and enhanced in lung tissues of both COPD patients and BALF of ozone-treated mice. We showed decreased E-cadherin and increased α-SMA expression in bronchial epithelium and increased RBM thickness in ozone-treated animals. In vitro, CSE, IL-1β and IL-17 enhanced NGAL mRNA expression in human neutrophils. NGAL, in turn, down-regulated the expression of E-cadherin and up-regulated α-SMA expression in 16HBE cells via the WNT/glycogensynthase kinase-3β (GSK-3β) pathway. Furthermore, NGAL promoted the proliferation and migration of human bronchial smooth muscle cells (HASMCs). The present study suggests that elevated NGAL promotes COPD airway remodelling possibly through altered EMT. NGAL may be a potential target for reversing airway obstruction and remodelling in COPD.

Immunohistology and remodeling in fatal pediatric and adolescent asthma

BackgroundThickening of reticular basement membrane, increased airway smooth muscle mass and eosinophilic inflammation are found in adult fatal asthma. At the present study the histopathology of fatal paediatric and adolescent asthma is evaluated.MethodsPost-mortem lung autopsies from 12 fatal asthma cases and 8 non-asthmatic control subjects were examined. Thickness of reticular basement membrane (RBM) and percentage of airway smooth muscle (ASM%) mass area were measured and inflammatory cells were counted. Patient records were reviewed for clinical history.ResultsThe age range of the cases was from 0.9 to 19.5 years, eight were males and five had received inhaled corticosteroids. Thickened RBM was detected in majority of the cases without any correlation to treatment delay, age at onset of symptoms or diagnosis. In the large airways ASM was clearly increased in one third of the cases whereas the median ASM% did not differ from that in healthy controls (14.0% vs. 14.0%). In small airways no increase of ASM was found, instead mucous plugs were seen in fatal asthma. The number of eosinophils, plasmacytoid dendritic cells, macrophages, and B-cells were significantly increased in fatal asthma cases compared with controls and the two latter correlated with the length of the fatal exacerbation.ConclusionsThe findings highlight the strong presence of eosinophils and mucous plugs even in small airways in children and adolescents with fatal asthma. Thickened RBM was obvious in majority of the patients. Contrary to our hypothesis, increased ASM% was detected in only one third of the patients.