Biomarkers to Predict Response to Inhaled Corticosteroids and Long-Acting Muscarinic Antagonists in Adolescents and Adults with Mild Persistent Asthma

Rationale: Whether biomarkers can be used to predict response to inhaled corticosteroids (ICS) or long-acting muscarinic antagonists (LAMA) in mild persistent asthma is unclear. Objectives: In a prespecified exploratory analysis of a randomized clinical trial of 295 participants 12 years of age or older with uncontrolled mild persistent asthma, we sought to identify biomarkers of treatment response after 12 weeks of ICS (mometasone, 200 μg or 220 μg twice/d), LAMA (tiotropium, 5 μg/d), or placebo in adults (⩾18 yr) and adolescents (12-17 yr) separately. Methods: The primary outcome was a composite outcome of asthma control (treatment failure, asthma control days, and forced expiratory volume in 1 second [FEV₁]). Analyses examined type 2 inflammatory biomarkers and physiologic biomarkers. We assessed the area under the receiver operating characteristic curve (AUC) for response to ICS and LAMA (each versus placebo). An AUC of 0.5 suggests no discrimination, 0.7-0.8 is considered acceptable, more than 0.8-0.9 is considered excellent, and more than 0.9 is considered outstanding. Results: In 237 adults, sputum and blood eosinophil levels and fractional exhaled nitric oxide (Fe_NO) each predicted ICS response (AUCs: 0.61 [95% confidence interval (CI), 0.53-0.69], 0.64 [95% CI, 0.56-0.72], and 0.62 [95% CI, 0.54-0.70], respectively; all P < 0.01); the AUC for blood eosinophil levels and Fe_NO together was 0.66 (95% CI, 0.58-0.74; P < 0.001). In 58 adolescents, the number of positive aeroallergens and total serum immunoglobulin E each predicted ICS response (AUCs: 0.69 [95% CI, 0.52-0.85] and 0.73 [95% CI, 0.58-0.87], respectively; both P < 0.03); the AUC for both together was 0.73 (95% CI, 0.58-0.87; P = 0.003). After ipratropium bromide, FEV₁ reversibility predicted LAMA response in adults (AUC: 0.61 [95% CI, 0.53-0.69], P = 0.007) but not in adolescents. Conclusions: The AUCs of the type 2 inflammatory biomarkers and physiological biomarkers we examined may not be high enough to confidently identify individuals with asthma who respond to ICS and LAMA. However, our findings indicate that the biomarkers that predict response to ICS or LAMA may differ in adults versus adolescents with uncontrolled mild persistent asthma. Prospective, biomarker-stratified clinical trials are needed to confirm these findings and to identify first-line controllers tailored for each population.

Predictive Markers of Bronchial Hyperreactivity in a Large Cohort of Young Adults With Cough Variant Asthma

Cough variant asthma (CVA), a common asthma phenotype characterized by nonproductive cough and bronchial hyperreactivity (BHR), is usually detected by bronchial provocation tests (BPTs) which are time-consuming, expensive, and unsafe. The primary study objective was to provide proof of concept for the use of fractional exhaled nitric oxide (F_ENO), eosinophil count percentage in induced sputum (sEOS%), forced expiratory flow between 25 and 75% of forced vital capacity (FEF_25–75%) % predicted value, and FEF_25–75% z-scores as surrogate markers predicting BHR in young adults with suspected CVA; the secondary objective was to compare the diagnostic performance of the various techniques. Three hundred and ten subjects (median age 24 years) were included in a cross-sectional study. Subjects were characterized as BHR positive (POS) (n = 147) or BHR negative (NEG) (n = 163) according to methacholine BPT. Classification accuracies were expressed as areas under the receiver operator characteristic curves (AUC). Compared with BHR NEG, FEF_25–75% % predicted value and FEF_25–75% z-scores were lower in the BHR POS group (p < 0.001), whereas F_ENO (p < 0.001) and sEOS% were higher (p < 0.001). AUC values for detecting BHR were as follows: F_ENO, 0.98 (SD = 0.02); sEOS%, 0.98 (SD = 0.02); FEF_25–75% % pred, 0.93 (SD = 0.05); FEF_25–75% z scores, 0.92 (SD = 0.05). Optimal cutoff values (OCV) for BHR prediction were as follows: F_ENO, 32.7 ppb (sensitivity = 0.93, specificity = 0.96), sEOS%, 3.80% (sensitivity = 0.94, specificity = 0.94), FEF_25–75% % predicted value, 80.0% (sensitivity = 0.90, specificity = 0.87), and FEF_25–75% z-score, −0.87 (sensitivity = 0.89, specificity = 0.87). Non-invasive/semi-invasive airway inflammatory or small airway functional measures might be used as surrogate markers predicting BHR in young adults with suspected CVA.

A comparative study evaluating C-reactive protein, sputum eosinophils and forced expiratory volume in one second in obese and nonobese asthmatics

ntroduction: Asthma and obesity are considered inflammatory disorders. Inflammatory markers - sputum eosinophils, C-reactive protein (CRP) and the forced expiratory volume in one second (FEV1) were analysed to find their association in obese asthmatics and compared with their asthma control test (ACT) to understand these parameters in this phenotype.

MATERIAL AND METHODS

After completing the asthma control test (ACT), the CRP, FEV1 and sputum eosinophils of sixty asthmatics were compared to find the association of them in obese and nonobese asthmatics and contrasted with their ACT. The data were analysed using IBM SPSS V20.0, Mann-Whitney U test (non-parametric test), Pearson's correlation coefficient and Fisher's exact test.

RESULTS

We found significant differences for CRP (P = 0.001) and sputum eosinophils (P = 0.001) between obese and nonobese asthmatics, both higher in obese asthmatics and with a significant association with body mass index (BMI) (P < 0.05). The FEV1 levels were independent of the BMI levels of asthmatics. There was a significant correlation between the CRP and sputum eosin-ophils (0.52, P = 0.001) for all asthmatics. There was no significant correlation between FEV1 and sputum eosinophils (nonobese P = 0.120, obese P = 0.388) and between FEV1 and CRP (obese P = 0.423, nonobese P = 0.358) in both obese and nonobese asthmatics. Obesity had an association (P = 0.001) with ACT scores (≤ 19).

CONCLUSIONS

Sputum eosinophils and CRP were raised in obese asthmatics and had a positive association with BMI. Obese asthmatics had a poorer subjective asthma control than nonobese asthmatics despite FEV1 being independent of the BMI levels. Measuring the systemic inflammatory markers could help in additional interventions in reducing systemic inflammation and thus possibly facilitating better symptom control.

Sputum Eosinophilia and Magnetic Resonance Imaging Ventilation Heterogeneity in Severe Asthma

RATIONALE

Inflammation and smooth muscle dysfunction are integral components of severe asthma that contribute to luminal obstruction causing airflow limitation, ventilation heterogeneity, and symptoms. This is important for guiding treatment decisions directed at the inflammatory (e.g., anti-T-helper cell type 2 monoclonal antibodies) and noninflammatory, smooth muscle-mediated (e.g., bronchial thermoplasty) components of severe asthma.

OBJECTIVES

To investigate the contribution of eosinophilic bronchitis and smooth muscle dysfunction to magnetic resonance imaging (MRI) ventilation heterogeneity in patients with severe asthma.

METHODS

We measured the inhaled hyperpolarized gas MRI response to salbutamol as a marker of smooth muscle dysfunction, and sputum eosinophils as a marker of airway inflammation, and their contributions to ventilation heterogeneity (quantified as the ventilation defect percent [VDP]) in 27 patients with severe asthma. Spirometry and forced oscillation airway resistance measurements were also acquired pre- and postsalbutamol. Patients were dichotomized on the basis of sputum eosinophilia, and pre- and postsalbutamol VDP and physiological measurements were evaluated.

MEASUREMENTS AND MAIN RESULTS

MRI VDP improved with salbutamol inhalation in patients in whom sputum eosinophilia was uncontrolled (≥3%, n = 16) (P = 0.002) and in those in whom it was controlled (<3%, n = 11) (P = 0.02), independent of improvements in FEV₁, indicating smooth muscle response. In those patients in whom sputum eosinophilia was uncontrolled, greater VDP persisted postsalbutamol (P = 0.004). Postsalbutamol VDP correlated with sputum eosinophils (r = 0.63; P = 0.005).

CONCLUSIONS

In patients with severe asthma, MRI regionally identifies the inflammatory and noninflammatory components of airway disease. Ventilation heterogeneity persists postsalbutamol in patients with uncontrolled eosinophilic bronchitis, which may be the functional consequence of airway inflammation.

Inflammatory profile in optimally treated patients with adult versus early-onset asthma

Introduction: The age of asthma onset is often implicated in clinical manifestation, diagnosis, and management of the disease. Aim: To define demographic, clinical and functional features and inflammatory characteristics in induced sputum in patients with adult-onset asthma. Methods: Optimally treated patients from asthma clinics of two tertiary hospitals were included in the study. Patients underwent assessment of demographic characteristics, severity and treatment regimes, pulmonary function tests, and skin prick tests, as well as measurement of blood eosinophils and sputum induction for the assessment of sputum inflammatory cells, IL-8 and IL-13 levels in the supernatant. Results: Of the 333 patients recruited, 234 (70.2%) had adult-onset asthma. Adult-onset asthmatics were older, had a higher BMI, a shorter disease duration, and were less often atopic, compared to patients with early onset asthma. Higher proportions of patients with severe asthma presented increased levels of FeNO and blood eosinophils, both in the early and the adult-onset patient groups. Finally, obese patients with early onset asthma were characterized by less atopy compared to non-obese patients in the same group. Conclusion: Adult-onset asthma was characterized by less sputum eosinophilia, a nonatopic profile and a higher BMI compared to early-onset asthma. The presence of blood eosinophilia and increased FeNO in patients with severe asthma was comparable in the two groups.

CT and Functional MRI to Evaluate Airway Mucus in Severe Asthma

BACKGROUND

Intraluminal contributor(s) to airflow obstruction in severe asthma are patient-specific and must be evaluated to personalize treatment. The occurrence and functional consequence of airway mucus in the presence or absence of airway eosinophils remain undetermined.

OBJECTIVE

The objective of this study was to understand the functional consequence of airway mucus in the presence or absence of eosinophils and to identify biomarkers of mucus-related airflow obstruction.

METHODS

Mucus plugs were quantified on CT scans, and their contribution to ventilation heterogeneity (using MRI ventilation defect percent [VDP]) was evaluated in 27 patients with severe asthma. Patients were dichotomized based on sputum eosinophilia such that the relationship between mucus, eosinophilia, and ventilation heterogeneity could be investigated. Fractional exhaled nitric oxide (Feno) and related cytokines in sputum were measured.

RESULTS

Mucus plugging was present in 100% of asthma patients with sputum eosinophils and 36% of those without sputum eosinophils (P = .0006) and was correlated with MRI VDP prebronchodilator (r = 0.68; P = .0001) and postbronchodilator (r = 0.72; P < .0001). In a multivariable regression, both mucus and eosinophils contributed to the prediction of postbronchodilator MRI VDP (R² = 0.75; P < .0001). Patients with asthma in whom the mucus score was high had raised Feno (P = .03) and IL-4 (P = .02) values. Mucus plugging correlated with Feno (r = 0.63; P = .005).

CONCLUSIONS

Both airway eosinophils and mucus can contribute to ventilation heterogeneity in patients with severe asthma. Patients in whom mucus is the dominant cause of airway obstruction have evidence of an upregulated IL-4/IL-13 pathway that could be identified according to increased Feno level.

Values of fractional exhaled nitric oxide for cough-variant asthma in children with chronic cough

BACKGROUND

Chronic cough is a common symptom in children. We wished to explore the value of fractional exhaled nitric oxide (FeNO) for cough-variant asthma (CVA) in children with chronic cough.

METHODS

This prospective cohort study was conducted in the Children's Hospital of Soochow University from January 2012 to December 2014. Children aged 6-14 years with a cough of duration >4 weeks were enrolled. They underwent FeNO measurement, sputum cytology and pulmonary function tests.

RESULTS

A total of 115 patients and 25 healthy controls were evaluated. For the diagnosis of CVA, the optimal FeNO cutoff value was 25 ppb with a sensitivity of 84.0%, specificity of 97.1%, positive predictive value of 97.5%, and negative predictive of being 81.4%. The FeNO level had a significant correlation with eosinophil count in sputum (P<0.05). FeNO level in CVA was decreased significantly after treatment (P=0.001).

CONCLUSIONS

In children, FeNO measurement might be an excellent method for diagnosing CVA with high sensitivity and specificity.

Diagnostic value of fractional exhaled nitric oxide for asthma-chronic obstructive pulmonary disease overlap syndrome

To examine the difference in the fractional exhaled nitric oxide (FeNO) between chronic obstructive pulmonary disease (COPD) patients with asthma-COPD overlap syndrome (ACOS) and patients with Non-ACOS COPD (Non-ACOS) and to investigate the correlation between FeNO levels and the differential cell counts of eosinophils in induced sputum, in order to explore the diagnostic value of FeNO in ACOS.A prospective, case-control study was performed on 53 cases of ACOS group and 53 cases of Non-ACOS group in the Respiratory Medicine Outpatient of Zhangzhou Municipal TCM Hospital, Affiliated to Fujian University of Traditional Chinese Medicine. The FeNO levels and induced sputum cell counts were determined and the correlation between FeNO levels and eosinophile percentage was analyzed by Pearson linear correlation analysis.The FeNO levels in patients with ACOS (37[24.5-53.0]) ppb were significantly higher than those of patients with Non-ACOS (20 [15.5-24.5] ppb) (P < .01). Also, the percentage of eosinophils in induced sputum in the ACOS group (5.70 [1.50-17.62]%) were significantly higher than those of the Non-ACOS group (0.50 [0.00-1.00]%) (P < .01). FeNO in both groups correlated positively with the percentage of eosinophils in induced sputum (P < .01), with a correlation coefficient r of 0.521. The area under the receiver operating curve of FeNO for the diagnosis of ACOS phenotype was 0.815 (P < .01), the sensitivity and specificity reach highest when the cut off value was 25.50 ppb.The FeNO in patients from the ACOS group were significantly higher than those in Non-ACOS group and were moderately correlated with the percentage of eosinophils in induced sputum. The results indicated that FeNO may be used as a diagnostic index for ACOS, in addition to the induced sputum.

Autoimmune Responses in Severe Asthma

Asthma and autoimmune diseases both result from a dysregulated immune system, and have been conventionally considered to have mutually exclusive pathogenesis. Autoimmunity is believed to be an exaggerated Th1 response, while asthma with a Th2 underpinning is congruent with the well-accepted Th1/Th2 paradigm. The hypothesis of autoimmune involvement in asthma has received much recent interest, particularly in the adult late-onset non-atopic patients (the “intrinsic asthma”). Over the past decades, circulating autoantibodies against diverse self-targets (beta-2-adrenergic receptors, epithelial antigens, nuclear antigens, etc.) have been reported and subsequently dismissed to be epiphenomena resulting from a chronic inflammatory condition, primarily due to lack of evidence of causality/pathomechanism. Recent evidence of ‘granulomas’ in the lung biopsies of severe asthmatics, detection of pathogenic sputum autoantibodies against autologous eosinophil proteins (e.g., eosinophil peroxidase) and inadequate response to monoclonal antibody therapies (e.g., subcutaneous mepolizumab) in patients with evidence of airway autoantibodies suggest that the role of autoimmune mechanisms be revisited. In this review, we have gathered available reports of autoimmune responses in the lungs, reviewed the evidence in the context of immunogenic tissue-response and danger-associated molecular patterns, and constructed the possibility of an autoimmune-associated pathomechanism that may contribute to the severity of asthma.

Sputum interleukin-13 as a biomarker for the evaluation of asthma control

BACKGROUND

Asthma control refers to the extent to which the manifestations of asthma have been reduced or eradicated by treatment. Interleukin-13 (IL-13) has a central role in Th2 response and serves as a possible therapeutic target in uncontrolled asthma. Fraction of exhaled nitric oxide (FeNO) and sputum eosinophils have modest performance in the evaluation of asthma control.

OBJECTIVE

To assess the diagnostic performance of sputum IL-13 for the evaluation of asthma control and furthermore to investigate the performance of sputum eosinophils and FeNO.

METHODS

One hundred and seventy patients with asthma were studied. All subjects underwent assessment of asthma control by asthma control test (ACT), lung function tests, FeNO measurement and sputum induction for cell count identification and IL-13 measurement in supernatants.

RESULTS

IL-13 (pg/mL) levels in sputum supernatant differed significantly among patients with well-controlled asthma and those with not well-controlled asthma [median IQR 78 (66-102) vs. 213 (180-265), P < 0.001]. Receiver operating characteristic (ROC) analysis showed that, for the whole study population, the diagnostic performance of IL-13 was superior to both sputum eosinophils and FeNO levels [area under the curve (AUC) 0.92, 95% CI 0.87 to 0.95 vs. AUC 0.65, 95% CI 0.58 to 0.72 vs. AUC 0.65, 95% CI 0.55 to 0.72, respectively].

CONCLUSION

The diagnostic performance of sputum IL-13 was superior to both sputum eosinophils and FeNO levels for the identification of well-controlled asthma. Sputum IL-13 levels could serve as a useful biomarker for asthma control assessment.

The effects of an epithelial barrier protective cationic aerosol on allergen-induced airway inflammation in asthma: a randomized, placebo-controlled clinical trial

Inhaled cationic airway lining modulator (iCALM) is a cationic aerosol therapy comprised of 1.29% calcium chloride dissolved in 0.9% isotonic saline that enhances the biophysical barrier function of the airway lining fluid and primes the host defense response. It's ability to attenuate bronchitis caused by inhaled particles was investigated using an allergen-inhalation model in a proof-of-concept study. In a randomized, double-blind, placebo-controlled cross-over trial of 6 mild atopic steroid-naïve asthmatic subjects, 3 doses of iCALM were well tolerated and they attenuated allergen-induced increase in sputum eosinophils, and levels of IL-5, MCP-1 and eotaxin. This study provides an opportunity to investigate the role of enhancing epithelial barrier to decrease airway inflammation provoked by inhaled particles in a variety of airway diseases.

A nonsteroidal glucocorticoid receptor agonist inhibits allergen-induced late asthmatic responses

RATIONALE

Effective antiinflammatory therapies are needed for the treatment of asthma, but preferably without the systemic adverse effects of glucocorticosteroids.

OBJECTIVES

We evaluated the effect of an inhaled nonsteroidal glucocorticoid receptor agonist, AZD5423, on allergen-induced responses.

METHODS

Twenty subjects with mild allergic asthma were randomized to receive 7 days of treatment with nebulized AZD5423 (75 or 300 μg) once daily, budesonide 200 μg twice daily via Turbuhaler, or placebo in a double-blind, four-period, crossover design study. Allergen challenge was performed on Day 6.

MEASUREMENTS AND MAIN RESULTS

FEV1 was measured repeatedly for 7 hours after allergen challenge for early and late asthmatic responses. Sputum inflammatory cells was measured before and at 7 and 24 hours after allergen challenge, and methacholine airway responsiveness was measured before and 24 hours after allergen challenge. AZD5423 significantly attenuated the fall in FEV1 during the late asthmatic response (both doses led to an 8.7% fall) versus placebo (14% fall) (P < 0.05) with no effect of budesonide (12.5% fall) versus placebo (P > 0.05). There was no effect on the fall in FEV1 during early asthmatic response. AZD5423 300 and 75 μg significantly attenuated allergen-induced sputum eosinophilia by 63 and 61% at 7 hours, respectively, and by 46 and 34% at 24 hours after allergen challenge, respectively, versus placebo (all P < 0.05). Budesonide did not reduce allergen-induced sputum eosinophilia versus placebo. AZD5423 at 300 μg significantly attenuated allergen-induced airway hyperresponsiveness at 24 hours after allergen challenge versus placebo (P < 0.05). Both doses of AZD5423 were well tolerated.

CONCLUSIONS

Seven-day treatment with inhalation of the nonsteroidal glucocorticoid receptor agonist AZD5423 effectively reduced allergen-induced responses in subjects with mild allergic asthma. Clinical trial registered with www.clinicaltrials.gov (NCT01225549).

Safety and efficacy of an oral CCR3 antagonist in patients with asthma and eosinophilic bronchitis: a randomized, placebo-controlled clinical trial

BACKGROUND

Several chemokines, notably eotaxin, mediate the recruitment of eosinophils into tissues via the CCR3 receptor.

OBJECTIVE

In this study, we investigated the role of CCR3 agonists in asthma by observing the effect of a small molecule antagonist of the CCR3 receptor (GW766994) on sputum eosinophil counts in patients with eosinophilic asthma.

METHODS

Clinical and physiological outcomes, the chemotactic activity of sputum supernatant for eosinophils and the presence of eosinophil progenitors in sputum and blood samples were also studied.

RESULTS

In a double-blind parallel group study, 60 patients with asthma were randomized to 300 mg of GW766994 twice daily or matching placebo for 10 days followed by prednisone 30 mg for 5 days. Of these patients, 53 had a sputum eosinophil count > 4.9% at baseline. Despite plasma concentrations of drug consistent with > 90% receptor occupancy during the dosing period, the CCR3 antagonist did not significantly reduce eosinophils or eosinophil progenitor cells (CD34(+) 45(+) IL-5Rα(+)) in sputum or in blood. The ex vivo chemotactic effect of sputum supernatants on eosinophils was attenuated by GW766944 compared to placebo. There was no improvement in FEV1 ; however, there was a modest but statistically significant improvement in PC20 methacholine (0.66 doubling dose) and ACQ scores, (0.43). Whilst the improvement in PC20 is statistically significant, it is not of clinical significance.

CONCLUSIONS AND CLINICAL RELEVANCE

In conclusion, this study calls into question the role of CCR3 in airway eosinophilia in asthma and suggests that other cellular mechanisms mediated by the CCR3 receptor may contribute to airway hyperresponsiveness.

Biomarker-based asthma phenotypes of corticosteroid response

BACKGROUND

Asthma is a heterogeneous disease with different phenotypes. Inhaled corticosteroid (ICS) therapy is a mainstay of treatment for asthma, but the clinical response to ICSs is variable.

OBJECTIVE

We hypothesized that a panel of inflammatory biomarkers (ie, fraction of exhaled nitric oxide [Feno], sputum eosinophil count, and urinary bromotyrosine [BrTyr] level) might predict steroid responsiveness.

METHODS

The original study from which this analysis originates comprised 2 phases: a steroid-naive phase 1 and a 28-day trial of ICSs (phase 2) during which Feno values, sputum eosinophil counts, and urinary BrTyr levels were measured. The response to ICSs was based on clinical improvements, including a 12% or greater increase in FEV1, a 0.5-point or greater decrease in Asthma Control Questionnaire score, and 2 doubling dose or greater increase in provocative concentration of adenosine 5'-monophosphate causing a 20% decrease in FEV1 (PC20AMP). Healthy control subjects were also evaluated in this study for comparison of biomarkers with those seen in asthmatic patients.

RESULTS

Asthmatic patients had higher than normal Feno values, sputum eosinophil counts, and urinary BrTyr levels during the steroid-naive phase and after ICS therapy. After 28-day trial of ICSs, Feno values decreased in 82% of asthmatic patients, sputum eosinophil counts decreased in 60%, and urinary BrTyr levels decreased in 58%. Each of the biomarkers at the steroid-naive phase had utility for predicting steroid responsiveness, but the combination of high Feno values and high urinary BrTyr levels had the best power (13.3-fold, P < .01) to predict a favorable response to ICS therapy. However, the magnitude of the decrease in biomarker levels was unrelated to the magnitude of clinical response to ICS therapy.

CONCLUSION

A noninvasive panel of biomarkers in steroid-naive asthmatic patients predicts clinical responsiveness to ICS therapy.

Clinical and biological markers of asthma control

Asthma has substantial impact on the patient, their family and health systems, and its control has gained increasing attention. Perception of asthma control has varied widely among patients as well as healthcare providers. Several clinical markers have been developed to define and standardize the measurement of asthma control. They are based primarily on patients' symptoms and have been popular in clinical practice and in clinical studies. With the advances in basic research on the pathology of asthma, several biological markers have evolved that have the advantages of being objective, quantitative and more reflective of the underlying pathology, which makes them a better guide for selecting optimal therapy. In addition to the cost and expertise required, biological makers are influenced by multiple factors that limit their application in clinical practice. Ongoing research is expected to define the role of individual biological markers, the optimal method of their application, and their appropriate interpretation.

Eosinophil peroxidase in sputum represents a unique biomarker of airway eosinophilia

BACKGROUND

Sputum eosinophilia has been shown to be a predictor of response to anti-eosinophil therapies in patients with airway diseases. However, quantitative cell counts and differentials of sputum are labor intensive. The objective of this study was to validate a novel ELISA-based assay of eosinophil peroxidase (EPX) in sputum as a rapid and reliable marker of airway eosinophils.

METHODS

The utility of EPX-based ELISA as an eosinophil-specific assay was achieved through comparisons with sputum eosinophil differential counts in freshly prepared and archived patient samples from a variety of clinical settings.

RESULTS

EPX levels in sputum correlated with eosinophil percentage (r(s) = 0.84) in asthma patients with varying degrees of airway eosinophilia. Significantly, unlike assays of other eosinophil granule proteins (e.g., ECP and EDN), which often detect the presence of these proteins even in asthma patients with neutrophilic bronchitis, EPX-based ELISA levels are not increased in this subset of asthma patients or in COPD patients lacking evidence of an airway eosinophilia. Moreover, sputum EPX was a surrogate marker of airway eosinophilia in other patient studies (e.g., allergen inhalation and treatment trials the anti-(IL-5) therapeutic Mepolizumab™). Finally, EPX levels in cytocentrifuged prepared sputum supernatants correlated with those from rapidly prepared noncentrifuged filtrates of sputum (r(s) = 0.94).

CONCLUSION AND CLINICAL IMPLICATION

EPX-based ELISA is a valid, reliable, repeatable, and specific surrogate marker of eosinophils and/or eosinophil degranulation in the sputum of respiratory patients. The novel EPX assay is a valid and reproducible eosinophil-specific assay that can potentially be developed into a point-of-care assessment of eosinophil activity in airway secretions.

Diffusion lung capacity of carbon monoxide: A novel marker of airways remodeling in asthmatic children?

Asthma is universally considered a chronic inflammatory disorder of the airways. Several noninvasive markers, such as exhaled nitric oxide (FeNO) and exhaled breath temperature (PletM), have been proposed to evaluate the degree of airway inflammation and remodeling in asthmatic children. The aim of this study was to evaluate the relationship between diffusion lung capacity of carbon monoxide (DLCO) and these inflammatory markers in asthmatic children. We compared data of FeNO, PletM, and DLCO collected in 35 asthmatic children at admission (T0) and discharge (T1) after a period spent in a dust-mite-free environment (Misurina, Italian Dolomites, 1756 m). PletM showed a reduction from 29.48°C at T0 to 29.13°C at T1 (p = 0.17); DLCO passed from 93 to 102 (p = 0.085). FeNO mean value was 29.7 ppb at admission and 18.9 ppb at discharge (p = 0.014). Eosinophil mean count in induced sputum was 4 at T0 and 2 at T1 (p = 0.004). Spearman standardization coefficient beta was 0.414 between eosinophils and FeNO and -0.278 between eosinophils and DLCO. Pearson's correlation index between DLCO and PletM was -0.456 (p = 0.019). A negative correlation between DLCO and PletM was found. However, DLCO did not show a significant correlation with FeNO and eosinophils in the airways. Additional studies are needed to clarify the role of DLCO as a potential tool in monitoring childhood asthma.