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.     

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.     

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.     

Interleukin-18 levels in induced sputum are reduced in asthmatic and normal smokers

BACKGROUND: IL-18 is a cytokine which is known to have an important role in the development of a Th1 lymphocyte response. As such, it may have a regulatory role in asthma by modifying Th2 lymphocyte responses. Cigarette smoking may amplify the airway inflammation associated with asthma. OBJECTIVE: This study investigated if IL-18 could be detected in induced sputum from asthmatics and normal subjects and if smoking altered IL-18 levels. METHODS: Induced sputum was obtained from asthmatic (31 smokers, 35 non-smokers) and normal (20 smokers, 20 non-smokers) subjects. All smokers had a smoking history of > or =15 pack years. IL-18 levels in sputum supernatant were measured by ELISA. IL-18 mRNA expression and cellular localization were assessed by quantitative PCR and immunocytochemistry, respectively. RESULTS: Smoking was associated with a significant reduction in IL-18 levels (median (interquartile range) - smokers 20 (0-102) pg/mL vs. non-smokers 358 (50-876) pg/mL, P<0.001). This was more pronounced in asthmatics (smokers, 47 (40-64) pg/mL vs. non-smokers, 530 (30-1484) pg/mL; P<0.001) than in normal subjects (smokers, 25 (0-78) pg/mL vs. non-smokers, 247 (50-656) pg/mL; P<0.01). Within each of the smoking and non-smoking groups there was no significant difference in IL-18 levels between asthmatic and normal subjects. There was no correlation between sputum IL-18 levels and any specific cell type in the sputum samples nor serum IgE levels. IL-18 mRNA expression was reduced in asthmatic smokers compared with non-smokers. IL-18 production was localized to sputum macrophages by immunocytochemistry. CONCLUSIONS: IL-18 is detectable in induced sputum samples from both asthmatic and normal subjects. Cigarette smoking significantly reduces sputum IL-18 levels. This effect is more pronounced in asthmatics than in normal subjects.     

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.     

Exhaled air temperature in asthma: methods and relationship with markers of disease

BACKGROUND: Exhaled breath temperature has been proposed as a surrogate marker for the evaluation of airway inflammation in asthmatic patients. OBJECTIVE: The aim of the present study was to extend the investigation of exhaled air temperature as a means for the evaluation of airway inflammation using a professionally developed instrument. METHODS: Fifty-seven children, 41 allergic mild asthmatics and 16 healthy controls have been evaluated. They underwent exhaled air temperature and lung function measurement. The asthmatic children also underwent exhaled nitric oxide measurement, and hypertonic saline sputum induction for the evaluation of eosinophil (EOS) percentage. RESULTS: The level of exhaled temperature was significantly higher in asthmatics than in controls, being 30.18+/-0.14 degrees C vs. 27.47+/-0.24 degrees C (P<0.001). In asthmatic children, a positive relationship was observed between exhaled air temperature and both exhaled nitric oxide (r=0.39; P=0.01) and EOS percentage in samples from induced sputum (rho=0.53; P=0.04). CONCLUSION: The data from the present study support the hypotheses that exhaled breath temperature is related to the degree of airway inflammation in asthma.     

VEGF levels in asthmatic airways do not correlate with plasma extravasation

BACKGROUND: Vascular permeability/vascular endothelial growth factor (VEGF) is a multifunctional cytokine which plays a role in chronic inflammation and angiogenesis. Its expression in bronchoalveolar lavage (BAL) has not been determined although VEGF may be relevant to the pathophysiology of asthma in which oedema is an important feature. METHODS: We studied VEGF, albumin and IgA immunoreactive levels in the BAL fluids obtained from 27 chronic stable asthmatics, nine untreated chronic bronchitis patients and 15 control subjects. RESULTS: BAL fluid levels of VEGF and VEGF normalized to IgA were not significantly different in any patient group. Both asthmatic steroid- and non-steroid-treated groups had significantly lower albumin levels in their BAL fluids explaining most of the 179% increased VEGF normalized to albumin ratios in non-steroid treated asthmatics. Moreover, VEGF and albumin markers correlated in control subjects (r = 0.73, P = 0.006) and in chronic bronchitics (r = 0.75, P = 0.03, Spearman test), but not in asthmatics. VEGF was inversely correlated with asthma severity (GINA/NHLBI scores) in non-steroid treated asthmatics (tau = - 0.52, P = 0.009, Kendall test). CONCLUSIONS: Thus, the potential role of VEGF in asthma requires further studies on bronchial biopsies and induced sputum.     

Association between asthma control and bronchial hyperresponsiveness and airways inflammation: a cross‐sectional study in daily practice

Background The primary end‐point in the management of asthma is to obtain optimal control. The aim of this study was to assess the relationships between the markers of airway inflammation (sputum eosinophilia and exhaled nitric oxide), bronchial hyperresponsiveness (BHR) and asthma control. Methods One hundred and thirty‐four patients were recruited from our asthma clinic between January 2004 and September 2005 [mean age: 42 years, mean forced expiratory volume in 1 s (FEV₁): 86% predicted]. Eighty‐six of them were treated by inhaled corticosteroids, 99 were atopic and 23 were current smokers. They all underwent detailed investigations including fractional‐exhaled nitric oxide (FE_NO) measurement, sputum induction and methacholine challenge when FEV₁ was >70% predicted, and filled in a validated asthma control questionnaire (ACQ6 Juniper). Results When dividing patients into the three groups according to their level of asthma control determined by ACQ [well‐controlled asthma (ACQ score 0.75), borderline (0.75<ACQ score <1.5) and uncontrolled asthma (ACQ score 1.5)], it appeared that uncontrolled asthmatics had a greater BHR to methacholine and sputum eosinophilia than controlled asthma (P<0.05, P<0.001, respectively). By contrast, we failed to show significant differences in the FE_NO levels between the groups. With receiver‐operating characteristic curves for differentiating uncontrolled (ACQ1.5) from controlled and borderline (ACQ<1.5) asthma, sputum eosinophilia and methacholine responsiveness were found to be more accurate than FE_NO (area under the curve: 0.72, 0.72 and 0.59, respectively). Conclusion In a broad spectrum of asthmatics encountered in clinical practice, sputum eosinophilia and methacholine bronchial hyperresponsiveness, but not FE_NO, are associated with uncontrolled asthma.     

House dust mite-specific IgE antibodies in induced sputum are associated with sputum eosinophilia in mite-sensitive asthmatics.

BACKGROUND: Although allergen-specific IgE antibodies have been considered to play an important role in the pathogenesis of atopic asthma, the role of IgE antibodies in the development of airway inflammation is not well defined. OBJECTIVE: To evaluate the association between allergen-specific IgE antibodies and inflammation of the asthmatic airway. METHODS: We measured house dust mite (HDM; Dermatophagoides farinae)-specific IgE antibodies in both serum and induced sputum from 16 HDM-sensitive asthmatic patients, and evaluated their association with sputum eosinophilia and eosinophil cationic protein (ECP) levels in induced sputum. RESULTS: Levels of HDM-specific IgE antibodies in induced sputum were significantly higher in asthmatic patients than in controls (P < .01). In asthmatic patients, levels of HDM-specific IgE antibodies were significantly higher in induced sputum samples with eosinophilia (sputum eosinophil count > or = 5% of 200 counted non-squamous cells) than in those without eosinophilia (P < .05). There were no significant differences in serum levels of HDM-specific IgE antibodies between asthmatic patients with sputum eosinophilia and asthmatic patients without sputum eosinophilia. In asthmatic patients, sputum ECP levels were significantly correlated with levels of HDM-specific IgE antibodies (r = 0.60, P = .01) in induced sputum but not with those in serum. CONCLUSION: We conclude that allergen-specific IgE antibodies in induced sputum from atopic asthmatics are associated with sputum eosinophilia. This result suggests that IgE-dependent mechanisms are involved in eosinophilic inflammation of the airway in atopic asthmatics.     

The bronchial response to mannitol is attenuated by a previous methacholine test: but not vice versa

Aim To examine the airway response to inhaled mannitol performed before or after a methacholine challenge test in a group of asthmatics with different levels of disease.
Methods A total of 48 asthmatics, 18–73 years of age, were included in the study. Two pairs of challenges were performed in a random order on two separate days 24 h apart: either with mannitol performed first on day one, followed 1 h by methacholine, and methacholine as the first on day two, followed 1 h by mannitol or vice versa. A questionnaire-based interview was performed and lung function, exhaled nitric oxide, skin prick test, and blood eosinophil count were measured.
Results A total of 44% of the asthmatics used inhaled corticosteroids and 48% were atopic. The airway response to mannitol was attenuated when mannitol was given after methacholine, compared with the response to mannitol when it was given first [log response dose ratio (RDR): 1.42 vs. 1.60 ( P =0.004)], whereas the response to methacholine was unchanged in the opposite test order [log RDR: 0.81 vs. 0.96 ( P =0.102)].
Conclusion Bronchial challenges with inhaled mannitol and methacholine may be performed on the same day but provocation with mannitol should be performed before methacholine.     

Airway neutrophil inflammation in nonasthmatic patients with food allergy

BACKGROUND: Patients with food allergy (FA) have been recently shown to develop bronchial hyperresponsiveness (BHR), despite the absence of any concomitant asthmatic manifestation. In order to explain this observation, we sought to examine the presence of a bronchial inflammation in induced sputum of nonasthmatic patients with FA. METHODS: Twelve nonasthmatic patients with FA (urticaria, digestive symptoms, anaphylaxis) were included in the study. Results were compared to these obtained from eight asthmatic patients without food allergy and eight healthy controls. Diagnosis of FA was based on double-blind placebo-controlled challenge. Sputum cells and fluid-phase eosinophil cationic protein (ECP), myeloperoxidase (MPO) and interleukin-8 (IL-8) were measured in induced sputum. BHR was evaluated using methacholine inhalation. RESULTS: Sputum from asthmatics, in comparison with the sputum of healthy subjects and patients with FA contained a higher proportion of eosinophils and higher levels of ECP (< 0.001). In marked contrast, patients with FA exhibited an increased proportion of neutrophils and IL-8 in comparison with asthmatics and controls (P < 0.05 for neutrophils and P < 0.001 for IL-8). There was a significant correlation between sputum neutrophils and IL-8 (r = 0.68, P < 0.001). MPO levels were not different between the groups. There was a trend toward higher levels of IL-8 and ECP in food allergic patients with BHR in comparison with patients with FA without BHR. CONCLUSION: Our results demonstrate that a subclinical neutrophil airway inflammation is present in patients with food allergy free of clinical respiratory symptoms and that IL-8 may be an important mediator of this neutrophilia.     

Exhaled breath condensate levels of eotaxin and macrophage-derived chemokine in stable adult asthma patients

Background Asthma is associated with esoinophilic airway inflammation and overproduction of T‐helper type 2 (Th2) lymphocyte‐related cytokines. Objective This study assessed the eosinophil chemoattractant eotaxin and Th2‐specific macrophage‐derived chemokine (MDC) in the adult asthmatic airway. Eotaxin and MDC levels were determined in exhaled breath condensate (EBC) obtained from adult patients with asthma. Methods Fifty‐four asthmatics (20 male, mean (SD) age 40 (12) years and percentage predicted forced expiratory volume in 1 s (FEV₁) 81.7 (20.8)) and 20 age‐ and sex‐matched controls were studied. EBC was collected using EcoScreen by 10 min of tidal breathing with a nose clip. Concentrations of eotaxin and MDC were measured by ELISA. Results Asthma patients on inhaled corticosteroid (ICS) had a higher median interquartile range (IQR) level of eotaxin than the steroid‐naïve asthmatics (18.5 (17.7–20.1) vs. 17.9 (17.0–18.6) pg/mL, P=0.02) and controls (18.5 (17.7–20.1) pg/mL vs 17.4 (16.3–18.0) pg/mL, P=0.001). Eotaxin level in EBC had a significant negative correlation with the FEV₁/forced vital capacity ratio (r=?0.43, P=0.03) in steroid‐naïve asthmatics. EBC MDC level was higher in subjects on ICS than the steroid naïve asthmatics (120 (118–125) vs. 117 (116–119) pg/mL, P=0.01) and the controls (120 (118–125) vs. 117 (116–120) pg/mL, P=0.02). Conclusions Eotaxin and MDC could be measured in EBC of adults with asthma. EBC eotaxin and MDC levels were higher in asthmatics on ICS than the steroid‐naïve asthmatics or controls. Exhaled chemokines may be potential non‐invasive markers for assessing airway inflammation in asthmatics.     

Intranasal steroid reduces exhaled bronchial cysteinyl leukotrienes in allergic patients

BACKGROUND: Allergic rhinitis (AR) precedes and is often associated with bronchial asthma. Indeed, local and systemic inflammations in both conditions are very similar. Cysteinyl-leukotrienes (cys-LTs) are generated during early- and late-phase allergic reactions and induce smooth-muscle contraction, microvascular leakage, and mucous hypersecretion. Cys-LTs are detected in exhaled breath condensate (EBC) of asthmatics and regardless of bronchial symptoms, they are also found in EBC of rhinitic patients. OBJECTIVE: To evaluate cys-LTs in EBC of allergic patients and to assess the activity of nasal fluticasone propionate (FP) on EBC cys-LTs levels. METHODS: Cys-LTs coefficient of variation (CV) was evaluated from different EBC in 5 healthy volunteers. Cys-LTs levels from EBCs in 13 healthy controls and 56 allergic rhinitic (n=31) and rhinitic/asthmatic (n=25) patients were also evaluated at baseline. Subsequently patients were randomized to receive either FP 100 microg/day per nostril or placebo for 2 weeks and then re-evaluated for EBC cys-LTs. RESULTS: The CV was 14.12%. EBC cys-LTs in allergic patients were significantly higher than in healthy subjects (70.9 vs. 20.6 pg/mL (median), P<0.05), while it did not differ between asthmatic/rhinitic and purely rhinitic patients. Treatment significantly reduced cys-LTs (from 93.6 to 19.9 pg/mL, P<0.001). This effect was evident both in asthmatic/rhinitic and in rhinitic patients. CONCLUSION: Treatment of AR with FP significantly reduces the levels of cys-LTs, major noninvasive markers of lower airway inflammation, suggesting that upper and lower airway inflammation is present and should be thus treated as a whole in subjects with AR with and without asthma.     

Airway inflammation in asthma and perennial allergic rhinitis. Relationship with nonspecific bronchial responsiveness and maximal airway narrowing

BACKGROUND: Eosinophilic airway inflammation is the hallmark of asthma, but it has also been reported in other conditions such as allergic rhinitis. We have tested whether the analysis of cells and chemicals in sputum can distinguish between patients with mild allergic asthma, those with allergic rhinitis, and healthy controls. The relationship between inflammation markers in sputum and nonspecific bronchial hyperresponsiveness to methacholine (BHR) (PD20 and maximal response plateau [MRP] values) was also evaluated. METHODS: We selected 31 mild asthmatics and 15 rhinitis patients sensitized to house-dust mite. As a control group, we studied 10 healthy subjects. Every subject underwent the methacholine bronchial provocation test (M-BPT) and sputum induction. Blood eosinophils and serum ECP levels were measured. Sputum cell differentials were assessed, and eosinophil cationic protein (ECP), tryptase, albumin, and interleukin (IL)-5 levels were measured in the entire sputum supernatant. RESULTS: Blood eosinophils and serum ECP levels were higher in asthma patients and rhinitis than in healthy controls, but no difference between asthma patients and rhinitis patients was found. Asthmatics had higher eosinophil counts and higher ECP and tryptase levels in sputum than rhinitis patients or control subjects. Sputum albumin levels were higher in asthmatics than in controls. Rhinitis patients exhibited higher sputum eosinophils than healthy controls. An association between sputum eosinophil numbers and MPR values (r= -0.57) was detected, and a trend toward correlation between sputum ECP levels and PD20 values (r= -0.47) was found in the rhinitis group, but not in asthmatics. No correlation between blood eosinophilic inflammation and lung functional indices was found. CONCLUSIONS: Induced sputum is an accurate method to study bronchial inflammation, allowing one to distinguish between rhinitis patients and mildly asthmatic patients. The fact that no relationship was detected between sputum inflammation and BHR suggests that other factors, such as airway remodeling, may be at least partly responsible for BHR in asthma.     

Concentrations of exhaled nitric oxide in asthmatics and subjects with allergic rhinitis sensitized to the same pollen allergen.

BACKGROUND: Some studies have reported that the levels of exhaled nitric oxide (ENO) in asthmatics are similar to those in subjects with allergic rhinitis, and it has been postulated that atopic status might be the determinant of enhanced nitric oxide production in asthma. OBJECTIVES: The aim of this study was to determine differences in ENO levels between asthmatics and subjects with allergic rhinitis sensitized to the same allergen, and to correlate these levels with airway responsiveness. METHODS: Nineteen patients with asthma and 18 subjects with allergic rhinitis monosensitized to Parietaria pollen were enrolled in the study. ENO values and airway responsiveness to methacholine and adenosine 5'-monophosphate (AMP) were measured during the pollen season. The response to each bronchoconstrictor agent was measured by the provocative concentration required to produce a 20% fall in FEV1 (PC20). ENO was measured with the single-exhalation method. RESULTS: The geometric mean (95% confidence interval) ENO values were significantly higher in asthmatics than in subjects with allergic rhinitis: 72.4p.p.b. (54.9-93.3p.p.b) vs. 44.7p.p.b. (30.9-64.6p.p.b., P = 0.03). In asthmatics, a significant correlation was found between ENO and PC20 AMP values (p = -0.57, P=0.02), whereas no correlation was detected between ENO and PC20 methacholine (p = -0.35, P = 0.14). CONCLUSIONS: Our results suggest that atopy is not the only determinant of increased ENO levels detected in subjects with asthma, and that responsiveness to AMP may be a more sensitive marker for assessing airway inflammation in asthma compared to methacholine.     

Changes in sputum cell counts after exposure to occupational agents: what do they mean?

BACKGROUND: Exposure to occupational agents can induce eosinophilic inflammation in subjects with occupational asthma (OA). It might also induce nonspecific changes in airway inflammation in subjects without OA. OBJECTIVES: We sought to investigate the changes in airway inflammation induced by exposure to occupational agents in subjects with and without OA and to determine which changes in sputum eosinophil numbers and bronchial responsiveness to methacholine should be regarded as clinically significant for predicting a 20% fall in FEV(1). METHODS: We performed specific inhalation challenges (SICs) in 3 groups of subjects: subjects reporting a history consistent with OA with a positive SIC response (n = 17); subjects reporting a history consistent with OA with a negative SIC response (n = 14); and asthmatic subjects without any history of OA (n = 10). Induced sputum and methacholine challenges were performed at the end of the control day and again at the end of the last day of exposure; the last day of exposure was always performed in the laboratory. RESULTS: There was an increase in median sputum eosinophil and neutrophil numbers in subjects with positive SIC responses. Cell counts remained unchanged after exposure in asthmatic subjects without OA. A combination of a greater than 0.26 10(6)/mL increase in sputum eosinophil numbers and a decrease in the concentration of methacholine inducing a 20% fall in FEV(1) of at least 1.8-fold compared with baseline values predicted a 20% fall in FEV(1) in 96% (95% CI, 70%-99%) of patients. CONCLUSION: Exposure to occupational agents per se does not induce airway inflammation. Changes in both sputum eosinophil counts and methacholine responsiveness are satisfactory predictors of a significant bronchial responsiveness to occupational agents.     

Relationship between airway responsiveness to mannitol and to methacholine and markers of airway inflammation, peak flow variability and quality of life in asthma patients

Background Airway hyperresponsiveness (AHR) to stimuli that cause bronchial smooth muscle (BSM) contraction indirectly through the release of endogenous mediators is thought to reflect airway inflammation more closely compared with AHR measured by stimuli that act directly on BSM. Methods Fifty‐three adult non‐smoking asthmatics (28 females, 18–56 years) who were not taking inhaled steroids were challenged with mannitol (up to 635 mg) and methacholine (up to 8 μmol). Induced sputum eosinophils, exhaled nitric oxide (eNO), peak flow variation and clinical severity of asthma according to the Global Initiative for Asthma guidelines were measured in addition to the health‐related quality‐of‐life score using the Juniper asthma quality‐of‐life questionnaire. Findings Both AHR to mannitol as well as to methacholine was associated with elevated markers of airway inflammation: in 83% of asthma patients with AHR to mannitol, and in 88% of asthma patients with AHR to methacholine, the eNO level was >20 p.p.b. Sputum% eosinophils >1% was measured in 70% of asthma patients with AHR to mannitol and in 77% of asthma patients with AHR to methacholine. In asthma patients without AHR, 15% had an eNO level >20 p.p.b., but none had sputum% eosinophils >1%. AHR to mannitol was more closely associated with the percentage of sputum eosinophils (PD₁₅ to mannitol vs. sputum% eosinophils: r: ?0.52, P<0.05), compared with AHR to methacholine (PD₂₀ to methacholine vs. sputum% eosinophils: r: ?0.28, NS). Furthermore, there was a stronger correlation between AHR to mannitol and the level of eNO [PD₁₅ to mannitol vs. eNO (p.p.b.): r: ?0.63, P<0.001], compared with AHR to methacholine [PD₂₀ to methacholine vs. eNO (p.p.b.): r: ?0.43, P<0.05]. Interpretation In asthma patients not being treated with steroids, AHR to mannitol and to methacholine indicated the presence of airway inflammation. AHR to mannitol reflected the degree of airway inflammation more closely when compared with methacholine.     

Effects of once daily dosing with inhaled budesonide on airway hyperresponsiveness and airway inflammation following repeated low-dose allergen challenge in atopic asthmatics

BACKGROUND: Repeated low-dose allergen challenge increases airway hyperresponsiveness and sputum eosinophils in atopic asthmatics. Inhaled corticosteroids attenuate the airway responses to high-dose allergen challenge, but have not been evaluated against repeated low dose challenge. OBJECTIVE: This study evaluates the effects of once daily treatments of two doses of inhaled budesonide on airway responses to repeated low-dose allergen challenge. METHODS: Eight atopic asthmatics with a dual airway responses to inhaled allergen were recruited into a randomized, double-blind crossover, placebo-controlled study. In the mornings of four consecutive days (day 1-day 4), subjects inhaled budesonide 100 microg, 400 microg, or placebo, 30 min before inhaling a concentration of allergen causing a 5% early fall in FEV1. Airway hyperresponsiveness to methacholine and sputum eosinophils were measured at baseline, on the afternoon of day 2, day 4, and 24 h after the last challenge. There was a 1-week washout between each of the three treatment periods. RESULTS: The repeated low-dose allergen challenge induced increases in the percentage sputum eosinophils from 2.0 +/- 0.7% at baseline to 16.6 +/- 7.1% on day 4 (P = 0.002), and this effect was reduced by once daily budesonide 100 microg to 5.6 +/- 1.8% (P = 0. 01) and by once daily budesonide 400 microg to 3.1 +/- 0.9% (P = 0. 004). Also, the allergen-induced methacholine airway hyperresponsiveness which occurred by day 4 (P = 0.03) of the repeated low dose challenge was inhibited by budesonide 400 microg (P = 0.017). CONCLUSION: Both budesonide 100 microg and 400 microg inhaled once daily significantly reduces allergen-induced sputum eosinophilia after repeated low dose challenge; however, only the higher dose also attenuates the allergen-induced airway hyperresponsiveness.     

Effect of histamine and adenosine 5'-monophosphate provocation on sputum neutrophils and related mediators in atopic patients.

BACKGROUND: Airway hyperresponsiveness and inflammation can be noninvasively studied by bronchial provocation using direct (histamine) or indirect (adenosine 5'-monophosphate [AMP]) stimuli and induced sputum. OBJECTIVE: To report on the immediate effects of histamine and AMP challenge on induced sputum neutrophil counts and related mediator levels. METHODS: We performed a single-masked, randomized, placebo-controlled, 3-way, crossover, methodological study in 14 atopic patients (median age, 25 years; 8 males; mean +/- SD forced expiratory volume in 1 second, 99% +/- 5%) without anti-inflammatory medication use. At baseline, sputum induction was performed. Bronchial challenges with AMP, histamine, or placebo were performed 48 hours later. Thirty minutes after challenge, sputum induction was performed again. Challenge periods in each patient were separated by more than 2 weeks. Sputum cells and the mediators leukotriene B4, interleukin 8, myeloperoxidase, and albumin were quantified. RESULTS: Comparing median challenge-induced relative changes in cells and mediators, neither histamine nor AMP challenge altered the induced sputum neutrophil counts (histamine, 2.7%; AMP, 2.95%; placebo, -2%; P > .07 for all), interleukin 8 levels (histamine, 2.4 ng/mL; AMP, -3.8 ng/mL; placebo, -0.2 ng/mL; P > .06), leukotriene B4 levels (histamine, -4.8 pg/mL; AMP, 3 pg/mL; placebo, 6 pg/mL; P > .08), or myeloperoxidase levels (histamine, 0.16 microg/mL; AMP, 0 microg/mL; placebo, -0.03 microg/mL; P > .07). Sputum albumin levels were increased after histamine challenge compared with AMP and placebo challenge (P < .01 for both). CONCLUSIONS: Histamine and AMP provocation have no major effects on induced neutrophil counts and related mediator levels in atopic patients, whereas histamine challenge induces plasma leakage. Potential interactions of noninvasive methods to evaluate airway reactivity and inflammation should be carefully considered.     

Airway mast-cell activation in asthmatics is associated with selective sputum eosinophilia

BACKGROUND: Tryptase is a serine endoprotease selectively released from mast cells. Although mast cells are known to be activated after experimental allergic provocation, their role in naturally occurring asthma is still debated. METHODS: We have investigated the levels of tryptase in the whole induced sputum collected from 51 asthmatics (31 atopic and 20 intrinsic) seen in our outpatient clinic and 22 normal nonatopic healthy volunteers. Tryptase was measured by a new immunoassay based on B12 monoclonal antibody recognition of total tryptase (UniCAP System, Pharmacia) with a sensitivity of 1 ng/ml. RESULTS: While being below the threshold of detection in all normal volunteers, tryptase was detectable in the sputum from 9/51 asthmatics (18%) including five atopic and four intrinsic asthma cases. In these patients, among whom three were asymptomatic asthmatics, the values ranged between 1 and 6.1 ng/ml. The asthmatics with detectable sputum tryptase had greater sputum eosinophil counts (P<0.05) but lower neutrophil counts (P<0.05) than those in whom tryptase was undetectable. When compared to control subjects, asthmatics without tryptase had still greater eosinophil counts (P<0.0001) but also raised neutrophil counts (P<0.05). No significant difference could be found between asthmatics with tryptase and those without tryptase with respect to the age, the baseline lung function, the methacholine bronchial responsiveness, and the frequency of treatment with inhaled steroids. CONCLUSIONS: With the UniCAP System, tryptase was detectable in the sputum from 18% of asthmatics irrespective of atopy and current symptoms. Asthmatics with tryptase appeared to have a selective increase in sputum eosinophil counts while those without tryptase displayed a mixed sputum granulocyte infiltration with raised eosinophil and neutrophil counts.