Jocelyne Sele

Exhaled nitric oxide thresholds associated with a sputum eosinophil count ≥3% in a cohort of unselected patients with asthma

Background It has been claimed that exhaled nitric oxide (FeNO) could be regarded as a surrogate marker for sputum eosinophil count in patients with asthma. However, the FeNO threshold value that identifies a sputum eosinophil count ≥3% in an unselected population of patients with asthma has been poorly studied. Methods This retrospective study was conducted in 295 patients with asthma aged 15–84 years recruited from the asthma clinic of University Hospital of Liege. Receiver-operating characteristic (ROC) curve and logistic regression analysis were used to assess the relationship between sputum eosinophil count and FeNO, taking into account covariates such as inhaled corticosteroids (ICS), smoking, atopy, age and sex. Results Derived from the ROC curve, FeNO ≥41 ppb gave 65% sensitivity and 79% specificity (AUC=0.777, p=0.0001) for identifying a sputum eosinophil count ≥3%. Using logistic regression analysis, a threshold of 42 ppb was found to discriminate between eosinophilic and non-eosinophilic asthma (p<0.0001). Patients receiving high doses of ICS (≥1000 μg beclometasone) had a significantly lower FeNO threshold (27 ppb) than the rest of the group (48 ppb, p<0.05). Atopy also significantly altered the threshold (49 ppb for atopic vs 30 ppb for non-atopic patients, p<0.05) and there was a trend for a lower threshold in smokers (27 ppb) compared with non-smokers (46 ppb, p=0.066). Age and sex did not affect the relationship between FeNO and sputum eosinophilia. When combining all variables into the logistic model, FeNO (p<0.0001), high-dose ICS (p<0.05) and smoking (p<0.05) were independent predictors of sputum eosinophilia, while there was a trend for atopy (p=0.086). Conclusion FeNO is able to identify a sputum eosinophil count ≥3% with reasonable accuracy and thresholds which vary according to dose of ICS, smoking and atopy.

Distribution of sputum cellular phenotype in a large asthma cohort: predicting factors for eosinophilic vs neutrophilic inflammation.

BackgroundPhenotyping asthma according to airway inflammation allows identification of responders to targeted therapy. Induced sputum is technically demanding. We aimed to identify predictors of sputum inflammatory phenotypes according to easily available clinical characteristics.MethodsThis retrospective study was conducted in 508 asthmatics with successful sputum induction recruited from the University Asthma Clinic of Liege. Receiver-operating characteristic (ROC) curve and multiple logistic regression analysis were used to assess the relationship between sputum eosinophil or neutrophil count and a set of covariates. Equations predicting sputum eosinophils and neutrophils were then validated in an independent group of asthmatics.ResultsEosinophilic (≥3%) and neutrophilic (≥76%) airway inflammation were observed in 46% and 18% of patients respectively. Predictors of sputum eosinophilia ≥3% were high blood eosinophils, FENO and IgE level and low FEV1/FVC. The derived equation was validated with a Cohen’s kappa coefficient of 0.59 (p < 0.0001). ROC curves showed a cut-off value of 220/mm3 (AUC = 0.79, p < 0.0001) or 3% (AUC = 0.81, p < 0.0001) for blood eosinophils to identify sputum eosinophilia ≥3%. Independent predictors of sputum neutrophilia were advanced age and high FRC but not blood neutrophil count.ConclusionEosinophilic and paucigranulocytic asthma are the dominant inflammatory phenotypes. Blood eosinophils provide a practical alternative to predict sputum eosinophilia but sputum neutrophil count is poorly related to blood neutrophils.

Sputum eosinophil count in a large population of patients with mild to moderate steroid-naive asthma: distribution and relationship with methacholine bronchial hyperresponsiveness

Background: Although airway eosinophilia is seen as a cardinal feature of asthma, data eosinophilia are still lacking on the proportion of the asthma group exhibiting raised airway eosinophilia. This study aimed to assess the distribution of sputum eosinophil count and its relationship with methacholine bronchial hyperresponsiveness in mild to moderate steroid‐naive asthmatic people.

Local and systemic cellular inflammation and cytokine release in chronic obstructive pulmonary disease

BACKGROUND Chronic obstructive pulmonary disease (COPD) is a chronic airway inflammatory disease caused by repeated exposure to noxious gases or particles. It is now recognized that the disease also features systemic inflammation. The purpose of our study was to compare airway and systemic inflammation in COPD to that seen in healthy subjects and to relate the inflammation with the disease severity. METHODS Ninety-five COPD patients, encompassing the whole severity spectrum of the disease, were recruited from our outpatient clinic and rehabilitation center and compared to 33 healthy subjects. Induced sputum and blood samples were obtained for measurement of inflammatory cell count. Interleukin (IL)-4, IL-6, IL-10, TNF-α and IFN-γ produced by 24h sputum and blood cell cultures were measured. RESULTS Compared to healthy subjects, COPD exhibited a prominent airway neutrophilic inflammation associated with a marked IL-10, IL-6 and TNF-α release deficiency that contrasted with a raised IFN-γ production. Neutrophilic inflammation was also prominent at blood level together with raised production of IFN-γ, IL-10 and TNF-α. Furthermore, sputum neutrophilia correlated with disease severity assessed by GOLD stages. Likewise the extent of TNF-α release from blood cells also positively correlated with the disease severity but negatively with that of sputum cell culture. Blood release of TNF-α and IL-6 negatively correlated with body mass index. Altogether, our results showed a significant relationship between cellular marker in blood and sputum but poor relationship between local and systemic release of cytokines. CONCLUSIONS COPD is characterized by prominent neutrophilic inflammation and raised IFN-γ production at both bronchial and systemic level. Overproduction of TNF-α at systemic level correlates with disease severity and inversely with body mass index.

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.

Cytokine production from sputum cells after allergenic challenge in IgE-mediated asthma

Background: Th2 cytokine production from airway cells is thought to govern the eosinophilic airways inflammation in allergic asthma. Induced sputum has become a widely used technique to assess airways inflammation.

Leukotriene B4 Contributes to Exhaled Breath Condensate and Sputum Neutrophil Chemotaxis in COPD

BACKGROUND Neutrophils have been implicated in the pathogenesis of COPD. Several chemoattractants for neutrophils have been measured in samples of exhaled breath condensate (EBC) and induced sputum (IS) from patients with COPD. The aims of this study were to compare EBC and IS supernatant neutrophil chemotactic activity (NCA) from ex-smoking subjects with COPD and healthy ex-smokers, and to assess the contribution of leukotriene B(4) (LTB(4)) to this activity. METHODS Thirty-four subjects with COPD were compared to 24 control subjects. EBC and IS chemotactic activity for neutrophils was assessed by using Boyden microchambers. The chemotactic index was used to evaluate cell migration. LTB(4) was measured by a specific enzyme immunoassay. The contribution of LTB(4) to EBC and sputum neutrophil chemotaxis was assessed by an LTB(4) receptor antagonist (U-75302; Cayman Chemical Company; Ann Arbor, MI). RESULTS EBC and IS samples from both COPD patients and healthy subjects displayed significant NCA, but this activity was raised in COPD patients compared to healthy subjects. The chemotactic activity contained in sputum, however, failed to correlate with that in EBC. In COPD patients, there was a significant correlation between EBC NCA and sputum neutrophil counts. LTB(4) levels were raised in EBC samples, but not in sputum samples, from COPD subjects compared to those from healthy subjects. LTB(4) receptor antagonist concentrations (2.5 x 10(-4) mol/L) reduced by 44.6% and by 44.4%, respectively, the chemotactic activity contained in the EBC and sputum samples. CONCLUSIONS EBC and IS from COPD patients have a raised NCA to which LTB(4) contributes.

Evidence of mast-cell activation in a subset of patients with eosinophilic chronic obstructive pulmonary disease

Although asthma has been viewed mainly as an eosinophilic disease, and chronic obstructive pulmonary disease (COPD) as a neutrophilic disease, recent studies have shown increased neutrophil counts in severe asthma and sputum eosinophilia in some COPD patients. In an attempt to further characterise these two syndromes according to pathology, the current authors have conducted a study of induced sputum in 15 subjects with COPD, 17 asthmatics, and 17 nonatopic healthy individuals. Sputum was analysed for cytology and levels of eosinophil cationic protein (ECP), albumin, tryptase and soluble intercellular adhesion molecule‐1. The COPD subjects differed from the asthmatics as they had higher sputum neutrophil and lower columnar epithelial cell counts, but there were no differences in any soluble marker studied. When compared to control subjects, both the asthmatic and COPD subjects had raised eosinophil counts and ECP levels. In a subset of COPD subjects with sputum eosinophilia (>3% of total cells), significantly increased levels of tryptase were detected. In conclusion, although chronic obstructive pulmonary disease is a more neutrophilic disease than asthma, the two diseases are difficult to distinguish on the basis of sputum levels of the soluble markers traditionally associated with asthma. However, a subset of patients with chronic obstructive pulmonary disease with airway eosinophilia and mast-cell activation might represent a distinct pathological phenotype.

Cytokine production from sputum cells in eosinophilic versus non-eosinophilic asthmatics.

The inflammatory pathways involved in asthma are more complex than the sole Th2‐mediated eosinophilic airway inflammation. Different phenotypes of asthma have been recently highlighted and are probably underlied by different immunological profiles. The aim of the study was to assess cytokine production from sputum cells in eosinophilic versus non‐eosinophilic asthmatics. Induced sputum was obtained from 48 consecutive stable mild to moderate asthmatics (20 eosinophilic asthmatics, 28 non‐eosinophilic asthmatics) and 31 healthy subjects. Cytokine released from sputum cells were measured by a home‐made two‐step sandwich immunoassay. Cytokines investigated were interleukin (IL)‐4, IL‐6, IL‐10, tumour necrosis factor (TNF)‐α and interferon (IFN)‐γ. Sputum cells from eosinophilic asthmatics produced more IL‐4 than those from both healthy subjects (P < 0·05) and non‐eosinophilic asthmatics (P < 0·05). Conversely, sputum cells from eosinophilic asthma were found to release lower amounts of TNF‐α than those from healthy subjects (P < 0·05). The group of non‐eosinophilic asthmatics did not distinguish from healthy subjects with respect to any cytokines measured. Sputum cells from asthmatics exhibiting eosinophilic airway inflammation release more IL‐4 and less TNF‐α than those of healthy subjects. By contrast, non‐eosinophilic asthmatics did not distinguish from healthy subjects by abnormal cytokine release from their sputum cells.

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.