Increased levels of vascular endothelial growth factor in induced sputum in asthmatic patients

BACKGROUND: Vascular endothelial growth factor (VEGF) is highly expressed in the airway of asthmatic patients. As VEGF increases airway vascular permeability, consequent thickening of the airway wall mucosa may lead to narrowing of the airway lumen. OBJECTIVE: We evaluated the relationship between VEGF levels in induced sputum and eosinophilic inflammatory profiles, and the degree of airway vascular permeability in asthmatic patients and we evaluated the effect of inhaled corticosteroids on VEGF levels in induced sputum. METHODS: Induced sputum specimens were obtained from 28 glucocorticosteroids free asthmatics and 11 healthy control subjects. We examined VEGF levels and airway vascular permeability index in induced sputum. After the initial sputum induction, 21 asthmatics received 8-week inhaled beclomethasone dipropionate (BDP, 800 micro g/day) therapy, then sputum induction was repeated. RESULTS: The VEGF levels in asthmatics were significantly higher than in healthy control subjects (P < 0.0001). The VEGF levels were negatively correlated with forced expiratory volume of 1 s (FEV1, % predicted, r = - 0.68, P < 0.001), the percentage of eosinophils (r = 0.51, P < 0.01) and ECP levels (r = 0.39, P < 0.05). Moreover, the VEGF levels were significantly correlated with airway vascular permeability index (r = 0.61, P < 0.001). After 8-week inhaled BDP therapy, the VEGF levels were significantly decreased compared to pretreatment levels (P < 0.0001) and the VEGF levels were significantly correlated with airway vascular permeability index even in post-treatment asthmatics (r = 0.62, P < 0.01). CONCLUSION: The VEGF levels in induced sputum were increased in asthmatics and its levels were associated with degree of airway narrowing and airway vascular permeability. These findings provide strong evidence that VEGF may play an important role in the pathogenesis of bronchial asthma.     

Expression of vascular endothelial growth factor, basic fibroblast growth factor, and angiogenin immunoreactivity in asthmatic airways and its relationship to angiogenesis

BACKGROUND: Angiogenesis is a prerequisite for airway remodeling in bronchial asthma. Several growth factors may play important roles in inflammation and angiogenesis through effects on inflammatory cell infiltration or neovascularization. OBJECTIVE: We sought to compare bronchial vascularity and expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and angiogenin in bronchial biopsy specimens from asthmatic and healthy control subjects. METHODS: Bronchial biopsy specimens were obtained from 16 asthmatic subjects and 9 normal control subjects. The number of vessel profiles and the vascular area per unit area on a histologic section were estimated by using computerized image analysis after staining for type IV collagen in vessel walls. Numbers of VEGF+, bFGF+, and angiogenin+ cells were determined by means of immunoreactivity. RESULTS: The airways of asthmatic subjects had significantly more vessels (P < .05) and greater vascular area (P < .001) than that observed in control subjects. Asthmatic subjects exhibited higher VEGF and bFGF and angiogenin immunoreactivity in the submucosa than did control subjects (P < .001, respectively). Significant correlations were detected between the vascular area and the numbers of angiogenic factor-positive cells (VEGF: rs = 0.93, P < .001; bFGF: rs = 0.83, P < .001; angiogenin: rs = 0.88, P < .001) within the asthmatic airways. Furthermore, the degree of vascularity was inversely correlated with airway caliber and airway responsiveness. Colocalization analysis revealed that the angiogenic factor-positive cells were CD34+ cells, eosinophils, and macrophages. CONCLUSION: Our results suggest that increased vascularity of the bronchial mucosa in asthmatic subjects is closely related to the expression of angiogenic factors, which may then contribute to the pathogenesis of asthma.     

Effect of beclomethasone dipropionate on basic fibroblast growth factor levels in induced sputum samples from asthmatic patients.

BACKGROUND: Airway remodeling in asthma refers to certain structural changes and is regulated by several growth factors. One molecule of potential relevance to these pathologic changes is basic fibroblast growth factor (bFGF). OBJECTIVES: To examine the relationship between bFGF levels and type III collagen synthesis in asthmatic airways and the effect of inhaled corticosteroid therapy on bFGF levels. METHODS: We simultaneously measured bFGF, vascular endothelial growth factor (VEGF), and procollagen type III peptide (P-III-P) levels in induced sputum samples from 17 asthmatic patients and 10 controls. Sputum induction was performed before and after 1 year of inhaled beclomethasone dipropionate therapy. RESULTS: Before beclomethasone dipropionate therapy, mean (SD) VEGF and bFGF levels were significantly higher in asthmatic patients (VEGF: 4270 [650] pg/mL; bFGF: 46.4 [20.0] pg/mL; P < .001 for both) than in controls (VEGF: 1730 [1140] pg/mL; bFGF: 6.0 [3.0] pg/mL). Although P-III-P was detected in none of the controls, P-III-P levels could be measured in all the asthmatic patients. No significant correlation was found between P-III-P and VEGF levels in asthmatic patients. However, a close correlation was found between bFGF and P-III-P levels in these patients (r = 0.84; P < .001). After 1 year of beclomethasone dipropionate therapy, VEGF levels were significantly decreased, whereas bFGF and P-III-P levels did not differ before vs after therapy. There remained a significant correlation between bFGF and P-III-P levels even after beclomethasone dipropionate therapy. CONCLUSIONS: A close correlation between bFGF and P-III-P levels was observed in asthmatic airways. However, corticosteroid therapy might not prevent airway remodeling via the bFGF-dependent pathway.     

A potent antiangiogenic factor, endostatin prevents the development of asthma in a murine model

BACKGROUND: Clinical studies suggest a role for angiogenesis in the development and persistence of chronic asthma, but whether angiogenic mediators contribute to acute asthma has not been fully studied. OBJECTIVE: The aim of this study was to investigate a role of vascular endothelial growth factor (VEGF), a major angiogenic and proinflammatory mediator, in allergen-induced acute asthma and to determine whether endostatin/Fc, a potent antiangiogenic factor can attenuate allergic airway responses. METHODS: We sensitized BALB/c mice with ovalbumin. We measured serum VEGF and examined immunoreactive VEGF around the airways 48 hours after the last challenge with either aerosolized PBS or ovalbumin once per day for 3 days. We also treated ovalbumin-sensitized mice with either endostatin/Fc or control fusion protein at the time of challenge with ovalbumin. We analyzed allergic airway responses 48 hours after the last ovalbumin challenge. RESULTS: Ovalbumin challenge induced immunolocalization of numerous VEGF-positive cells around airways and increased serum VEGF levels. Treatment with endostatin/Fc inhibited the airway hyperresponsiveness, pulmonary allergic inflammation, production of ovalbumin-specific IgE, and lung inflammatory mediators. Both VEGF-dependent and independent mechanisms are indicated by results using antibody blockade of VEGF receptors, which caused decreased allergic pulmonary inflammation but did not alter airway hyperresponsiveness or serum IgE levels. CONCLUSION: These data demonstrate for the first time that recombinant endostatin can prevent the development of asthma features in a mouse model and suggest that this class of agents merits further study as novel therapeutics for asthma.     

Airway angiogenesis in patients with rhinitis and controlled asthma

Background Airway angiogenesis may be an important part of structural remodelling in the pathogenesis of asthma. The development of asthma is frequently preceded by rhinitis.
Objective We sought to determine whether the levels of angiogenesis-related factors are elevated in airways of patients with rhinitis or controlled asthma.
Methods We analysed the induced sputum of 18 rhinitis patients, 16 asthmatic patients, and 15 healthy controls. The concentrations of angiogenin, vascular endothelial growth factor (VEGF), IL-8, fibroblast growth factor (bFGF), and TNF-α were measured by cytometric bead arrays.
Results We found significantly increased angiogenin and VEGF concentrations in the induced sputum supernatant of both rhinitis and asthma patients compared with that of the healthy control group ( P 0.0005). With the exception of TNF-α, there was no difference in the other angiogenic factors; TNF-α levels were higher in the rhinitis group than in the control group ( P =0.02).
Conclusion These in vivo results suggest increased airway angiogenesis in patients with rhinitis without asthma as well as in corticosteroid-treated and well-controlled asthma patients.     

Imbalance in the production between vascular endothelial growth factor and endostatin in Kawasaki disease

To investigate whether an imbalance exists in the production between angiogenic and antiangiogenic growth factors in patients with Kawasaki disease (KD), we measured the serum levels of vascular endothelial growth factor (VEGF) and endostatin (ES) in 35 patients with KD, 15 patients with acute febrile diseases (disease controls) and 15 healthy children. KD patients had significantly higher VEGF levels and lower ES levels (P < 0.01) in the acute and subacute phases than the disease control and healthy children. KD patients with coronary artery lesions (CAL, n = 10) had significantly higher VEGF levels and lower ES levels (P < 0.05) in the subacute and convalescent phases than those without CAL (n = 25). The ratios of VEGF/ES in sera of KD patients with CAL were significantly higher (P < 0.05) in the acute and convalescent phases compared to those without CAL. Furthermore, the occurrence of CAL significantly correlated with the VEGF/ES ratio above 10 x 10(-3) in the subacute phase of KD (Odds ratio 17.25, P = 0.005). The findings in the present study indicate that an imbalance exists in the production between VEGF and ES in patients with KD while also suggesting that KD patients with a high VEGF/ES ratio have a significantly greater risk of CAL involvement.     

Effect of combined hormonal and insulin therapy on the steroid hormone receptors and growth factors signalling in diabetic mice prostate

Diabetes causes harmful effects on prostatic morphology and function. However, there still are doubts about the occurrence of various diseases in the prostate, as well as abnormal angiogenesis in relation to diabetes. Thus, the aim of this study was to correlate and quantify the level of the steroid hormone receptors and the angiogenic and antiangiogenic factors in non-obese diabetic mice (Nod) after combined hormonal and insulin therapy. Sixty mice were divided into six groups after 20 days of diabetes: the control group received 0.9% NaCl, as did the diabetic group. The diabetic-insulin group received insulin, the diabetic-testosterone group received testosterone cypionate, the diabetic-oestrogen group received 17β-oestradiol, and the diabetic-insulin-testosterone-oestrogen group received insulin, testosterone and oestrogen simultaneously. After 20 days, the ventral lobe was processed for immunocytochemical and hormonal analyses. The results showed that the lowest serum testosterone and androgen receptor levels were found in the diabetic group and the highest testosterone and androgen receptor levels in the diabetic-insulin-testosterone-oestrogen group. The serum oestrogen level and its receptor showed changes opposite to those of testosterone and its receptor. The endostatin reactivity was mainly decreased in diabetic mice. The greatest IGFR-1 and VEGF reactivities occurred in diabetic mice. Thus, diabetes led to the prostatic hormonal imbalance, affecting molecular dynamics and angiogenesis in this organ. Combined insulin and steroid hormone therapy partially restored the hormonal and angiogenic imbalance caused by diabetes.     

Increased prostaglandin E2 concentrations and cyclooxygenase-2 expression in asthmatic subjects with sputum eosinophilia

BACKGROUND: Prostaglandin E2 (PGE2) is known to be produced within human airways, but it is not clear whether in airway diseases it can play a deleterious or a beneficial role. Recently it has been reported that PGE2 can enhance eosinophil survival in vitro. OBJECTIVE: To evaluate whether the concentrations of PGE2 in asthmatic airways correlate with the number of eosinophils and can be responsible for eosinophil-enhanced survival and to identify the cyclooxygenase isoform contributing to the synthesis of PGE2 by cells present in asthmatic airways. METHODS: Reversed-phase high-performance liquid chromatography and/or specific radioimmunoassay was used to measure PGE2 concentrations in induced sputum supernatants from 14 control and 30 asthmatic subjects. Correlations between concentrations of PGE2 and the number of eosinophils in induced sputum were evaluated. Expression of cyclooxygenase-2 (COX-2) in induced sputum cells was determined by immunocytochemistry, and the effect of COX-2 inhibition on PGE2 production was evaluated with the use of radiolabeled arachidonic acid. The effects on eosinophil apoptosis by PGE2 or induced sputum supernatants were studied by using peripheral blood eosinophils obtained by negative immunomagnetic selection. RESULTS: PGE2 concentrations resulted in elevated samples from asthmatic subjects and directly correlated with the percentage of eosinophils and the concentrations of eosinophilic cationic protein. Immunostaining for COX-2 showed enhanced expression in macrophages of asthmatic subjects when compared with control subjects, and the use of a specific COX-2 inhibitor provided evidence that PGE2 synthesis was the result of COX-2 enzymatic activity in asthma-induced sputum cells. Supernatant from induced sputum of asthmatic subjects with high eosinophil counts caused a decreased apoptosis of peripheral blood eosinophils when compared with control subjects, and immunoprecipitation of PGE2 significantly reverted this phenomenon, suggesting that PGE2 was present in biologically relevant concentrations in induced sputum. CONCLUSIONS: The results obtained suggest that COX-2 expression in alveolar macrophages from asthmatic subjects may contribute to enhanced eosinophil survival through an increased PGE2 production.     

IL-17 is increased in asthmatic airways and induces human bronchial fibroblasts to produce cytokines.

BACKGROUND: IL-17 is a cytokine that has been reported to be produced by T lymphocytes. In vitro, IL-17 activates fibro-blasts and macrophages for the secretion of GM-CSF, TNF-alpha, IL-1beta, and IL-6. A number of these cytokines are involved in the airway remodeling that is observed within the lungs of asthmatic individuals. OBJECTIVE: In this study, we investigated the expression of IL-17 in sputum and bronchoalveolar lavage specimens obtained from asthmatic subjects and from nonasthmatic control subjects. METHODS: IL-17 was detected through use of immunocytochemistry, in situ hybridization, and Western blot. Bronchial fibroblasts were stimulated with IL-17, and cytokine production and chemokine production were detected through use of ELISA and RT-PCR. RESULTS: Using immunocytochemistry, we demonstrated that the numbers of cells positive for IL-17 are significantly increased in sputum and bronchoalveolar lavage fluids of subjects with asthma in comparison with control subjects (P <.001 and P <.005, respectively). We demonstrated that in addition to T cells, eosinophils in sputum and bronchoalveolar lavage fluids expressed IL-17. Peripheral blood eosinophils were also positive for IL-17, and the level of IL-17 in eosinophils purified from peripheral blood was significantly higher in subjects with asthma than in controls (P <.01). To further investigate the mechanism of action of IL-17 in vivo, we examined the effect of this cytokine on fibroblasts isolated from bronchial biopsies of asthmatic and nonasthmatic subjects. IL-17 did enhance the production of pro-fibrotic cytokines (IL-6 and IL-11) by fibroblasts, and this was inhibited by dexamethasone. Similarly, IL-17 increased the level of other fibroblast-derived inflammatory mediators, such as the alpha-chemokines, IL-8, and growth-related oncogene-alpha. CONCLUSION: Our results, which demonstrate for the first time that eosinophils are a potential source of IL-17 within asthmatic airways, suggest that IL-17 might have the potential to amplify inflammatory responses through the release of proinflammatory mediators such as alpha-chemokines.     

Macrophage migration inhibitory factor (MIF) in bronchial asthma

BACKGROUND: Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine favouring the secretion of TNFalpha and IL-8 and counteracts anti-inflammatory effects of corticosteroids. Airways inflammation is a central feature of bronchial asthma and is characterized by the accumulation of eosinophils. OBJECTIVE: The aim of this study was to investigate whether MIF is related to asthma symptoms and eosinophil accumulation in the airways. METHODS: Serum MIF levels were measured by an enzyme-linked immunosorbent assay in 44 healthy subjects and 44 asthmatics. Levels of MIF in induced sputum were measured in 10 healthy subjects and 15 asthmatics. Levels of eosinophil cationic protein (ECP) in induced sputum were measured by a radioimmunosorbent assay. Fluorescence double immunostaining was conducted to examine cellular source and localization of MIF. RESULTS: Serum MIF levels were significantly increased in asthmatic patients compared with age and sex-matched control subjects. Symptomatic patients had a higher MIF level than asymptomatic patients. Induced sputum obtained from asthmatics contained higher levels of MIF than those from control subjects. MIF levels in induced sputum were correlated with ECP levels in induced sputum. MIF was colocalized with eosinophil peroxidase staining in the cytoplasm of sputum cells. CONCLUSION: Increased MIF levels are associated with asthma symptoms and one of the cellular sources of MIF in the airways are eosinophils.     

Effects of inhaled corticosteroids on exhaled leukotrienes and prostanoids in asthmatic children

BACKGROUND: Lipid mediators play an important pathophysiologic role in atopic asthmatic children, but their role in the airways of atopic nonasthmatic children is unknown. OBJECTIVE: We sought (1) to measure leukotriene (LT) E 4 , LTB 4 , 8-isoprostane, prostaglandin E 2 , and thromboxane B 2 concentrations in exhaled breath condensate in atopic asthmatic and atopic nonasthmatic children; (2) to measure exhaled nitric oxide (NO) as an independent marker of airway inflammation; and (3) to study the effect of inhaled corticosteroids on exhaled eicosanoids. METHODS: Twenty healthy children, 20 atopic nonasthmatic children, 30 steroid-naive atopic asthmatic children, and 25 atopic asthmatic children receiving inhaled corticosteroids were included in a cross-sectional study. An open-label study with inhaled fluticasone (100 microg twice a day for 4 weeks) was undertaken in 14 steroid-naive atopic asthmatic children. RESULTS: Compared with control subjects, exhaled LTE 4 ( P <.001), LTB 4 ( P <.001), and 8-isoprostane ( P <.001) levels were increased in both steroid-naive and steroid-treated atopic asthmatic children but not in atopic nonasthmatic children (LTE 4 , P=.14; LTB 4 , P=.23; and 8-isoprostane, P=.52). Exhaled NO levels were increased in steroid-naive atopic asthmatic children ( P <.001) and, to a lesser extent, in atopic nonasthmatic children ( P <.01). Inhaled fluticasone reduced exhaled NO (53%, P <.0001) and, to a lesser extent, LTE 4 (18%, P <.01) levels but not LTB 4 , prostaglandin E 2 , or 8-isoprostane levels in steroid-naive asthmatic children. Conclusions Exhaled LTE 4 , LTB 4 , and 8-isoprostane levels are increased in atopic asthmatic children but not in atopic nonasthmatic children. In contrast to exhaled NO, these markers seem to be relatively resistant to inhaled corticosteroids.     

Increased levels of angiopoietin-2 in induced sputum from smoking asthmatic patients

Background Active cigarette smoking has detrimental effects on asthma morbidity and severity. Angiopoietin‐1 has been shown to protect the microvessels against plasma leakage, whereas angiopoietin‐2 enhances vascular permeability and subsequently induces airway mucosal oedema. Therefore, it is recently thought that angiopoietin‐2 may contribute to the pathophysiology of asthma. Objective To determine whether angiopoietin‐2 levels in the airways are associated with clinical profiles in smoking asthmatics. Methods We measured angiopoietin‐1 and ‐2 levels in induced sputum in 35 normal controls (18 non‐smokers and 17 smokers) and 49 asthmatics (24 non‐smokers and 25 smokers) before and after inhaled beclomethasone dipropionate (BDP: 800 μg/day) therapy for 12 weeks. Results Angiopoietin‐1 and ‐2 levels in induced sputum were significantly higher in asthmatics than in normal controls. Moreover, angiopoietin‐2 levels were significantly higher in smoking asthmatics than in non‐smoking asthmatics (P=0.0001). The airway vascular permeability index was also higher in smoking asthmatics than in non‐smoking asthmatics. Moreover, the angiopoietin‐2 level was positively correlated with the airway vascular permeability index (non‐smoking asthmatics: r=0.87, P<0.001, smoking asthmatics: r=0.64, P=0.002). After BDP therapy, angiopoietin‐1 levels were significantly decreased in non‐smoking asthmatics, smoking‐cessation asthmatics, and active‐smoking asthmatics. In contrast, angiopoietin‐2 levels did not differ from before to after BDP therapy in non‐smoking asthmatics and active‐smoking asthmatics. However, its levels were significantly decreased from before to after BDP therapy in smoking‐cessation asthmatics (P=0.002). Although forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) before BDP therapy was comparable in all subgroups, this parameter after BDP therapy was significantly lower in active‐smoking asthmatics than in non‐smoking and smoking‐cessation asthmatics. Moreover, the reduction in angiopoietin‐2 levels after BDP therapy in smoking‐cessation asthmatics was significantly correlated with an mprovement in FEV₁/FVC. Conclusion Angiopoietin‐2 levels were elevated in the airways of smoking asthmatics, and its levels were associated with impaired airway responses.     

Nitric oxide metabolites in induced sputum: a marker of airway inflammation in asthmatic subjects

BACKGROUND AND OBJECTIVE: The role of nitric oxide (NO) needs to be further clarified in allergic inflammation. This study was designed to investigate the relationships between NO metabolites and eosinophil count, eosinophil cationic protein (ECP), interleukin (IL)-5 in induced sputum from asthmatics. METHODS: Hypertonic saline-induced sputum was obtained in 25 asthmatic subjects, among which 13 patients were examined before and after anti-asthmatic medications including steroid preparations. Ten normal subjects were enrolled as controls. Fresh expectorated sputum separated from saliva was treated with equal volume of dithiothreitol 0.1%, cytospinned for cell count, and the supernatant was collected for biochemical assay. NO metabolites were assayed by using modified Griess reaction. ECP was measured by fluoroimmunoassay, and detected IL-5 by a sandwich ELISA. RESULTS: Asthmatic subjects, compared with controls, had significantly higher concentration of NO metabolites (1035.4 +/- 125.3 vs 557.2 +/- 101.5 micromol/L, P < 0.01), higher percentage of eosinophils (25.6 +/- 4.6 vs 1.7 +/- 0.2%, P < 0.01), and higher levels of ECP (1117.8 +/- 213.9 vs 154.6 +/- 47.4 microg/L, P < 0.01) in the induced sputum. IL-5 was detected more frequently in asthmatic subjects than in control subjects (11/25 [44%] vs 1/10 [10%], P < 0.05). According to asthma severity, moderate to severe asthmatic subjects (n = 18) had higher level of NO metabolites (1143.8 +/- 156.3 vs 575.5 +/- 89.5 micromol/L, P < 0. 01), higher levels of ECP and IL-5 (P < 0.01, respectively) in the induced sputum than in those of mild asthmatic subjects (n = 7). NO metabolites, the percentage of eosinophils, the levels of ECP, and IL-5 were reduced following treatment with anti-asthmatic drugs (P < 0.01, respectively). There were significant positive correlations between NO metabolites and percentage of eosinophils or ECP (r = 0. 34, P < 0.05; r = 0.28, P < 0.05). Negative correlations were noted between FEV1, FEV1/FVC and proportion of eosinophils, ECP, or IL-5 levels. CONCLUSION: These findings confirmed that the level of NO metabolites was increased in the tracheobronchial secretion of asthmatic subjects and was paralleled with severity of asthma. Measurement of NO metabolites in induced sputum may be used for monitoring the degree of airway inflammation in asthmatics.     

Downmodulation of CXCL8/IL-8 receptors on neutrophils after recruitment in the airways

BACKGROUND: CXCL8/IL-8 is the most significant chemokine for neutrophils, and CXC chemokine receptor (CXCR) 1 and 2 are its 2 receptors, which are downmodulated by CXCL8/IL-8 and endotoxin on activated neutrophils. OBJECTIVE: We sought to evaluate the expression of the CXCL8/IL-8 receptors and the activation marker CD11b on neutrophils in peripheral blood and in the site of airway inflammation. METHODS: The flow cytometric expression of CXCR1, CXCR2, and CD11b was evaluated on peripheral blood and induced sputum neutrophils in patients with nonsevere asthma with greater than 60% sputum neutrophils, in patients with chronic obstructive pulmonary disease (COPD), and in healthy control subjects. RESULTS: Asthmatic patients and patients with COPD had comparable expressions of CXCR1, CXCR2, and CD11b on peripheral blood and sputum neutrophils. Compared with control subjects, the peripheral neutrophil expression of CXCR2 was lower in patients with COPD ( P = .03) and that of CD11b was higher in asthmatic patients and patients with COPD ( P < .02 and P < .002). The expression of the CXCL8/IL-8 receptors on sputum neutrophils was markedly lower than on peripheral blood neutrophils ( P < .0001). The downmodulation of CXCL8/IL-8 receptors was also present in healthy control subjects but less than that seen in asthmatic patients. The difference between peripheral blood and sputum expression of CXCL8/IL-8 receptors correlated with serum CXCL8/IL-8 levels. In asthmatic patients the expression of CXCR1 and CXCR2 on sputum neutrophils negatively correlated with sputum neutrophils. CONCLUSION: In neutrophilic asthma the expression of CXCL8/IL-8 receptors on peripheral and sputum neutrophils is similar to COPD and negatively correlated with the inflammatory infiltrate in the airways. The downmodulation of CXCL8/IL-8 receptors detected in the airways should be taken into account for an eventual therapeutic inhibition of these receptors.     

Differential roles of IL-16 and CD28/B7 costimulation in the generation of T-lymphocyte chemotactic activity in the bronchial mucosa of mild and moderate asthmatic individuals

BACKGROUND: IL-16 is an important T-cell chemotactic cytokine in asthmatic airways; its release from allergen-stimulated bronchial mucosa in mild asthma has been shown to be dependent on CD28/B7 costimulation. OBJECTIVE: We have extended our previous studies to investigate the role of IL-16 and CD28/B7 costimulation in T-lymphocyte chemotactic activity (TLCA) released from the bronchial mucosa in more severe asthma. METHODS: TLCA was determined in the supernatants of induced sputum and allergen-stimulated bronchial mucosal explants from healthy volunteers and volunteers with mild and moderately severe asthma by means of a Boyden chamber technique. The contribution of IL-16 to the activity was evaluated through use of a neutralizing monoclonal antibody; the contribution of CD28/B7 costimulation to allergen-induced release of TLCA was determined through use of CTLA4-Ig fusion protein and neutralizing monoclonal antibodies to CD80 (B7.1) and CD86 (B7.2). RESULTS: Induced sputum and unstimulated explants from asthmatic subjects generated significant spontaneous TLCA (P <.05). Both mild and moderate asthmatic explants showed significantly elevated Dermatophagoides pteronyssinus -induced release of TLCA, but only in mild asthma could sputum and allergen-stimulated explant TLCA be inhibited by anti-IL-16 (median inhibition, 39% and 59%; P <.05). In addition, allergen released significant quantities of IL-16 from mild asthmatic explants (P <.05) but not from moderate asthmatic explants. Antibodies to the CD28 counter-ligands CD80 and CD86 inhibited allergen-induced release of TLCA in mild asthmatic explants by 94% (P <.05) and 62%, but TLCA release from moderate asthmatic explants was unaffected by CTLA4-Ig. CONCLUSION: These results show that TLCA release in moderate asthmatic airways, in contrast to mild asthmatic airways, is not dependent on CD28/B7 costimulation and does not involve IL-16.     

Role of endogenous nitric oxide in exercise-induced airway narrowing in patients with bronchial asthma

BACKGROUND: Increased amounts of nitric oxide (NO) in expired air and induced sputum have been found in asthmatic patients, and the role of excessively produced NO in the pathogenesis of bronchial asthma is under active investigation. OBJECTIVE: This study was designed to investigate the involvement of endogenous NO in exercise-induced bronchoconstriction (EIB) in asthmatic patients by using the sputum induction method. METHODS: The concentration of NO derivatives and inflammatory indices in induced sputum were examined in 18 asthmatic subjects and 10 normal control subjects. All asthmatic subjects performed an exercise test for 6 minutes. For 8 weeks after the first exercise testing, 400 microg of beclomethasone dipropionate twice daily was administered for asthmatic subjects with EIB, and the exercise testing and sputum induction were repeated in these patients. RESULTS: The concentration of NO derivatives in induced sputum was significantly higher in 9 asthmatic subjects with EIB (1580 +/- 280 micromol/L) than in 9 asthmatic subjects without EIB (1130 +/- 210 micromol/L) and normal control subjects (510 +/- 150 micromol/L). Moreover, there was a significant correlation between the concentration of NO derivatives and the percentage of maximal fall in FEV(1) (r = 0.569, P =.019). The concentration of NO derivatives was also more closely correlated with the area under the curve of the percentage fall in FEV(1) plotted against time for 30 minutes (AUC(0-30); r = 0.812, P <.001). After treatment with inhaled beclomethasone dipropionate in asthmatic subjects with EIB, there was a significant decrease in the concentration of NO derivatives in induced sputum. The change in the concentration of NO derivatives was significantly correlated with the change in the AUC(0-30) (r = 0.896, P =.0114) but not with the change in the percentage of maximal fall in FEV(1). CONCLUSION: These findings suggest that excessive production of NO is associated with EIB in patients with asthma and contributes to the prolonged airway narrowing phase rather than to the maximal airway narrowing evoked by exercise.     

Gene expression of vascular endothelial growth factor and its receptors and angiogenesis in bronchial asthma

BACKGROUND: Angiogenesis is a feature of airway remodeling in bronchial asthma. The mechanism responsible for this angiogenesis is unknown. Vascular endothelial growth factor (VEGF) is a potent inducer of endothelial cells, which may contribute to chronic inflammation and angiogenesis. OBJECTIVE: We sought to investigate the molecular mechanisms underlying increased vascularity, and we examined the mRNA expression of VEGF and its receptors (flt-1 and flk-1) within bronchial biopsy specimens from asthmatic patients and normal control subjects. METHODS: Endobronchial biopsy specimens were examined immunocytochemically by staining with anti-type IV collagen mAb to evaluate vessel density by using computer-assisted image analysis. Specimens were also analyzed for the presence of the mRNAs of VEGF and its receptors with in situ hybridization. RESULTS: The extent of airway vascularity was increased in asthmatic subjects compared with that in control subjects (P <.01). Asthmatic subjects exhibited a greater expression of VEGF, flt-1, and flk-1 mRNA(+) cells in the airway mucosa compared with that in control subjects (P <.001 for each comparison). The degree of vascularity was associated with the number of VEGF, flt-1, and flk-1 mRNA(+) cells. Numbers of cells expressing VEGF mRNA inversely correlated with airway caliber (r = -0.83, P <.01) and airway hyperresponsiveness (r = -0.97, P <.001). Colocalization studies showed that macrophages, eosinophils, and CD34(+) cells were the major sources of VEGF; CD34(+) cells, macrophages, and T cells expressed both flt-1 and flk-1. CONCLUSION: These findings provide evidence that VEGF may play an important role in angiogenesis and subsequent airway remodeling in bronchial asthma.     

Analysis of vascular endothelial growth factor levels in induced sputum samples from patients with cough variant asthma.

BACKGROUND: We previously found that vascular endothelial growth factor (VEGF) levels in induced sputum samples are increased in patients with classic asthma and are associated with the degree of airflow obstruction and airway microvascular permeability. OBJECTIVE: To examine VEGF levels and the degree of airway microvascular permeability in patients with cough variant asthma (CVA). METHODS: Levels of VEGF in induced sputum samples and airway microvascular permeability were examined in 12 controls, 16 patients with CVA, and 16 patients with classic asthma. We also evaluated the relationship between VEGF level and the clinical features of these 2 disorders. RESULTS: Mean (SD) VEGF levels and airway vascular permeability index values were significantly higher in patients with CVA (VEGF: 2,520 [1,050] pg/mL; P < .001; vascular permeability index: 0.017 [0.006]; P = .003) and classic asthma (4,750 [1,260] pg/mL; P < .001; 0.028 [0.009]; P < .001) than in controls (1,420 [1,230] pg/mL; 0.009 [0.003]). Furthermore, these values were significantly higher in patients with classic asthma vs CVA. We also found significant correlations between VEGF level and airway vascular permeability index in patients with CVA (r = 0.60; P = .02) vs classic asthma (r = 0.83; P = .001). Furthermore, VEGF levels were inversely correlated with the degree of airflow obstruction and airway hyperresponsiveness to methacholine in patients with CVA and classic asthma. CONCLUSIONS: Airway microvascular hyperpermeability induced by elevated VEGF levels contributes to abnormal airway function in CVA and classic asthma, and differences in the clinical features of these 2 disorders may depend on airway VEGF levels.     

A calcium-activated chloride channel (HCLCA1) is strongly related to IL-9 expression and mucus production in bronchial epithelium of patients with asthma

BACKGROUND: One of the cardinal features of airway remodeling in asthma is mucus gland hyperplasia and mucus overproduction and hypersecretion. Recently, a calcium-activated chloride channel, HCLCA1, was described that is upregulated by IL-9 and thought to regulate the expression of soluble gel-forming mucins, such as MUC5A/C, a critical component of mucus in the airways. OBJECTIVE: We sought to examine the expression of HCLCA1 in bronchial biopsy specimens of asthmatic subjects compared with those of control subjects and to demonstrate its relationship with IL-9, IL-9 receptor (IL-9R), and markers of mucus production. METHODS: Bronchial biopsy specimens from asthmatic (n = 9) and control (n = 10) subjects were stained with periodic acid-Schiff to identify mucus glycoconjugates. IL-9- and IL-9R-positive cells were identified with immunocytochemistry, and HCLCA1 expression was detected by means of in situ hybridization with cRNA probes. RESULTS: We demonstrate significant increases in IL-9 (P <.001) and IL-9R (P <.05) immunoreactivity, as well as increased expression of HCLCA1 mRNA (P <.001), in the epithelium of asthmatic patients compared with that found in control subjects. There was also an increase in the number of mucusproducing cells in biopsy specimens from asthmatic subjects (P <.001). HCLCA1 mRNA was strongly and selectively colocalized with periodic acid-Schiff and IL-9R-positive epithelial cells. In particular, a strong positive correlation was observed between HCLCA1 mRNA expression and IL-9-positive (r = 0.69, P < 0.01) or IL9R-positive (r = 0.79, P <.01) cells. CONCLUSION: An upregulation of HCLCA1 in the IL-9- responsive mucus-producing epithelium of asthmatic subjects compared with that seen in control subjects supports the hypothesis that this channel may be responsible, in part, for the overproduction of mucus in asthmatic subjects. These preliminary findings suggest the inhibition of HCLCA1 may be an important new therapeutic approach to control mucus overproduction in chronic airway disorders.