Background Structural changes to the airways are features of severe asthma. The bronchial epithelium facilitates this remodeling process. Learning about the changes that develop in the airway ...epithelium could improve our understanding of asthma pathogenesis and lead to new therapeutic approaches. Objective We sought to determine the feasibility and relevance of air-liquid interface cultures of bronchial epithelium derived from endobronchial biopsy specimens of patients with different severities of asthma for studying the airway epithelium. Methods Human bronchial epithelial cells derived from endobronchial biopsy specimens of patients with mild and severe asthma were maintained in culture for 21 days in an air-liquid interface to reproduce a fully differentiated airway epithelium. Initially, features of remodeling that included epithelial and subepithelial layers, as well as mucus production, were assessed in paraffin-embedded endobronchial biopsy specimens to evaluate morphologic characteristics of asthmatic patients’ epithelia. Ex vivo differentiated epithelia were then analyzed for morphology and function based on ultrastructural analysis, IL-8 release, lipoxin A4 generation, mucin production, and lipoxygenase gene expression. Results Morphologic and inflammatory imbalances initially observed in endobronchial biopsy specimens obtained from patients with severe or mild asthma persisted in the air-liquid interface reconstituted epithelium throughout the differentiation process to 21 days. Epithelium from patients with severe asthma produced greater levels of mucin, released more IL-8, and produced lower levels of lipoxin A4 than that from patients with mild asthma. Expression of 15-lipoxygenase 2 was increased in epithelium from patients with severe asthma, whereas expression levels of MUC5AC, MUC5B, 5-lipoxygenase, and 15-lipoxygeanse 1 were similar to those of patients with mild asthma. Conclusion Ex vivo cultures of fully differentiated bronchial epithelium from endobronchial biopsy specimens maintain inherent phenotypic differences specifically related to the severity of asthma.
Leptin and leptin receptor expression in asthma Bruno, Andreina, PhD; Pace, Elisabetta, MD; Chanez, Pascal, MD ...
Journal of allergy and clinical immunology,
08/2009, Volume:
124, Issue:
2
Journal Article
Peer reviewed
Open access
Background The adipokine leptin is a potential new mediator for bronchial epithelial homeostasis. Asthma is a chronic inflammatory disease characterized by airway remodeling that might affect disease ...chronicity and severity. TGF-β is a tissue growth factor the dysregulation of which is associated with airway remodeling. Objective We sought to determine whether a bronchial epithelial dysfunction of the leptin/leptin receptor pathway contributes to asthma pathogenesis and severity. Methods We investigated in vitro the presence of leptin/leptin receptor on human bronchial epithelial cells. Then we studied the effect of TGF-β and fluticasone propionate on leptin receptor expression. Finally, the role of leptin on TGF-β release and cell proliferation was analyzed. Ex vivo we investigated the presence of leptin/leptin receptor in the epithelium of bronchial biopsy specimens from subjects with asthma of various severities and from healthy volunteers, and some features of airway remodeling, such as reticular basement membrane (RBM) thickness and TGF-β expression in the epithelium, were assessed. Results In vitro bronchial epithelial cells express leptin/leptin receptor. TGF-β decreased and fluticasone propionate increased leptin receptor expression, and leptin decreased the spontaneous release of TGF-β and increased cell proliferation. Ex vivo the bronchial epithelium of subjects with mild, uncontrolled, untreated asthma showed a decrease expression of leptin and its receptor and an increased RBM thickness and TGF-β expression when compared with values seen in healthy volunteers. Furthermore, severe asthma was associated with a reduced expression of leptin and its receptor and an increased RBM thickness with unaltered TGF-β expression. Conclusions Decreased expression of leptin/leptin receptor characterizes severe asthma and is associated with airway remodeling features.
Background Reticular basement membrane (RBM) thickness is considered a hallmark for airway remodeling in airway diseases such as asthma. It is still unclear whether this measurement could be ...associated with disease severity or apply to chronic obstructive pulmonary disease (COPD). A wide range of results, at baseline or after therapeutic intervention, have been reported using different measurement methods. Objective To determine whether increased RBM thickness could be associated specifically with severe asthma and in COPD in large samples. Methods We blindly measured RBM thickness in endobronchial biopsies from 50 patients with severe asthma (mean age, 53 years; FEV1 66% predicted, inhaled steroids ≥1500 μg and 20 mg daily dose of oral corticosteroids, lifelong nonsmokers), 50 untreated patients with mild asthma (mean age, 33 years; FEV1 93%pred, lifelong nonsmokers), 50 patients with COPD (mean age, 57 years; FEV1 53%pred, all current smokers), and 18 control subjects using 2 different validated quantitative and computer-assisted methods (repeated multiple point-to-point vs area by length ratio). Results Reticular basement membrane thickness was higher in severe asthma compared with mild asthma and COPD ( P = .0053). On the basis of receiver operating characteristic curves, RBM thickness was effective in differentiating severe asthma from other groups (sensitivity and specificity, 98% and 95%, respectively, above a threshold of 5 μm vs control, 70% and 75% at 7 μm vs mild, 83% and 68% at 6 μm vs COPD). Conclusion Increased RBM thickness was specifically associated with severe asthma, whereas surprisingly, COPD and mild asthma had similar remodeling features. Clinical implications Reticular basement membrane thickness can be considered a hallmark of severe asthma.
Energy intake, weight gain, carcass composition, plasma fuels, hepatic metabolites and lipogenic enzyme activities were studied in adult rats fed either a low fat, high carbohydrate (LF) diet or one ...of two fat-containing diets in which 32% of the metabolizable energy was constituted by long-chain triglycerides (LCT) or medium-chain triglycerides (MCT). Compared with the LF diet, the MCT diet did not depress food and energy intake, weight gain, energy and nitrogen retention or lipid deposition and did not produce ketogenesis. The weight gain of rats fed LCT was 25% higher, and increased lipid deposition was observed. Lower lipogenic enzyme activities were observed in rats fed the LF diet containing 4% corn oil than in rats fed the MCT diet containing 1% corn oil. This effect disappeared when rats previously adapted to the LCT diet were fed LF or MCT diets containing 1% corn oil for 21 d. By d 21, in both groups, hepatic malic enzyme, ATP-citrate lyase, acetyl CoA carboxylase and fatty acid synthase activities were 2.2-, 2.0-, 2.3- and 1.8-fold higher than those of rats fed LCT. intermediate hepatic glucose-6-phosphate dehydrogenase activities were observed in rats fed the MCT diet, compared with LCT (40% lower) and LF (1.6-fold higher) diets. These data show that in rats fed a diet in which MCT supplies 32% of metabolizable energy, a high activity of lipogenic enzymes is observed, suggesting that MCT had no inhibitory effect on the activity of these enzymes
Background Determination of future risk of exacerbations is a key issue in the management of asthma. We previously developed a method to calculate conditional probabilities (π) of future decreases in ...lung function by using the daily fluctuations in peak expiratory flow (PEF). Objective We aimed to extend calculation of π values to individual patients, validated by using electronically recorded data from 2 past clinical trials. Methods Twice-daily PEF data were analyzed from 78 patients with severe (study A) and 61 patients with poorly controlled (study B) asthma. For each patient, the π value was calculated from 5000 PEF data points simulated based on the correlation and distribution properties of observed PEF. Given an initial PEF, the π value was defined as the probability of a decrease in PEF to less than 80% of predicted value on 2 consecutive days within a month. These probabilities were then compared with actual occurrences of such events and clinically defined exacerbations within the following month. Results π Values were related to actual occurrences of decreases in PEF (adjusted R2 > 0.800 for both studies). Every increase of 10% in π value was associated with an odds ratio of having a future exacerbation of 1.24 (95% CI, 1.07-1.43) for study A and 1.13 (95% CI, 1.02-1.26) for study B, with better sensitivity and specificity than clinic-measured FEV1. Conclusion These results from 2 independent datasets with differing asthmatic populations and differing exacerbation criteria provide support that clinically relevant quantification of individual future risk of exacerbations is possible.
Background Lipoxins are biologically active eicosanoids with anti-inflammatory properties. Lipoxin A4 (LXA4 ) signaling blocks asthmatic responses in human and experimental model systems. There is ...evidence that patients with respiratory diseases, including severe asthma (SA), display defective generation of lipoxin signals despite glucocorticoid therapy. Objective We investigated airway levels of formyl peptide receptor 2–lipoxin receptor (FPR2/ALXR), LXA4 , and its counterregulatory compound, leukotriene B4 (LTB4 ), in patients with childhood asthma. We addressed the potential interplay of the LXA4 -FPR2/ALXR axis and glucocorticoids in the resolution of inflammation. Methods We examined LXA4 and LTB4 concentrations in induced sputum supernatants from children with intermittent asthma (IA), children with SA, and healthy control (HC) children. In addition, we investigated FPR2/ALXR expression in induced sputum cells obtained from the study groups. Finally, we evaluated in vitro the molecular interaction between LXA4 and glucocorticoid receptor–based mechanisms. Results We found that children with SA have decreased LXA4 concentrations in induced sputum supernatants in comparison with children with IA. In contrast to decreases in LXA4 concentrations, LTB4 concentrations were increased in children with asthma independent of severity. LXA4 concentrations negatively correlated with LTB4 concentrations and with exacerbation numbers in children with SA. FPR2/ALXR expression was reduced in induced sputum cells of children with SA compared with that seen in HC subjects and children with IA. Finally, we describe in vitro the existence of crosstalk between LXA4 and glucocorticoid receptor at the cytosolic level mediated by G protein–coupled FPR2/ALXR in peripheral blood granulocytes isolated from HC subjects, children with IA, and children with SA. Conclusion Our findings provide evidence for defective LXA4 generation and FPR2/ALXR expression that, associated with increased LTB4 , might be involved in a reduction in the ability of inhaled corticosteroids to impair control of airway inflammation in children with SA.
Blood eosinophil counts do not represent an overall view of airway inflammation, and exhaled nitric oxide measurements at different flow rates (fraction of exhaled nitric oxide Feno and alveolar ...nitric oxide Calvno) have been developed and validated to reflect more accurately proximal and distal airway inflammation.2 Club cell secretory protein (CCSP) serum concentration has been shown to be associated with chronic obstructive pulmonary disease, bronchiolitis obliterans syndrome, and sarcoidosis, which are all predominantly diseases involving the small airways. CT air trapping was quantified by using expiratory/inspiratory ratios of the mean lung density (E/I MLD), and airway wall thickness as a reflection of proximal airway remodeling was assessed by computing the square root of the wall area of a 10-mm luminal perimeter (Pi10) index.4 To quantify the progression of air trapping during the course of the bronchial provocation test, the dose-response slope (DRS) of E/I MLD was computed as follows: Formula omitted. ...we have identified a potential blood biomarker relevant to small-airway hyperresponsiveness observed during dynamic CT acquisition in asthmatic patients. Variables: Y = log(E/I MLD DRS) Univariate analyses Multivariate analysis Coefficient SE P value Coefficient SE P value Age (y) −0.054 0.018 .007 BMI (kg/m2) −0.031 0.041 .449 ACQ-6 score −0.093 0.387 .812 Baseline FEV1 (% predicted) −2.705 2.799 .342 Baseline FVC (% predicted) −1.285 2.745 .644 Baseline FEV1/FVC ratio −0.081 0.045 .086 FVC decrease at PC20 (%) −7.289 5.560 .201 Log (FVC DRS) 1.237 0.221 <.001 1.18409 0.15398 <.001 Feno (ppb) 0.017 0.013 .197 Corrected Calvno (ppb) 0.098 0.060...
Background Nuclear factor-κB (NF-κB) is a transcriptional factor of different inflammatory patterns involved in asthma and chronic obstructive pulmonary disease (COPD) that is tightly controlled by ...IκB kinase (IKK) complex. Objective We investigated the dysregulation of IKK-driven NF-κB activation in patients with asthma and COPD. Methods We assessed IKKα and IKKβ expression and activation, their regulation by glucocorticosteroids, and their involvement in IL-8 synthesis in PBMCs isolated from asthmatic patients, healthy smokers (HSs), patients with COPD, and control subjects. PBMCs from control subjects were stimulated with TNF-α and cigarette smoke extract in the presence or absence of fluticasone propionate (FP), L-glutathione reduced, or both, and IKK activation and IL-8 release were evaluated. Results IKKα activity was higher in patients with COPD and HSs than in asthmatic patients and control subjects. IKKβ activity was higher in asthmatic patients, HSs, and patients with COPD than in control subjects. In vitro FP treatment induced inhibition of both IKKα and IKKβ activity in PBMCs from asthmatic patients, patients with COPD, and HSs, although IKKβ activity was more sensitive to FP than that of IKKα. FP reduced the IL-8 released from PBMCs of asthmatic patients, patients with COPD, and HSs, although IL-8 inhibition was higher in asthmatic patients than in patients with COPD and HSs. FP reduced IKKα and IKKβ activities in TNF-α and cigarette smoke extract–treated PBMCs, with higher levels of inhibition for IKKβ than IKKα activity. L-glutathione reduced improved the downregulatory effects of FP on IKKα and IL-8 levels. Conclusion Based on differential activation of IKKα and IKKβ, our findings suggest a different profile in the upstream regulation of the IKK-driven NF-κB system in asthmatic patients and patients with COPD. These differences in the regulation of the inflammatory process may explain, at least in part, the different pharmacologic responses in these patients.
Background Air trapping reflects small airway obstruction in asthma and can be assessed quantitatively by high-resolution computed tomography (HRCT). Hydrofluoroalkane-beclomethasone dipropionate ...(HFA-BDP) is deposited across all sizes of airways, including the small ones. However, its long-term effect on air trapping remains unknown in uncontrolled asthma. Objectives To compare the effect of inhaled corticosteroids of different particle size—HFA-BDP and fluticasone propionate (FP)—on lung attenuation in mild-to-moderate uncontrolled asthma. Methods A randomized study was performed to analyze the effect of HFA-BDP (400 μg/d) or FP (500 μg/d) given over a period of 3 months to patients with uncontrolled mild-to-moderate asthma. HRCT was performed with spirometric gating, and lung attenuation was measured at residual volume and at pulmonary total capacity. The difference between inspiratory and expiratory attenuation was calculated as an air trapping index. Results Twenty-five out of 58 patients had abnormal air trapping and could be included in the study. Lung attenuation significantly diminished in the posterior zones of the lung after a 3-month treatment with HFA-BDP or FP, but the difference between the groups was not significant. Adjusted mean variations of the air trapping index from baseline to treatment completion were 34.3 (11.2, 57.3) and 27.3 (6.4, 48.2) for the HFA-BDP and FP groups, respectively. However, the reduction of air trapping area was more pronounced in the group treated with HFA-BDP. Conclusion Inhaled corticosteroids decrease air trapping in uncontrolled asthma regardless of their particle size. Clinical implications In mild-to-moderate asthma, air trapping assessed by HRCT may be a new outcome related to the control of the disease.
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