Use of induced sputum to examine airway inflammation in childhood asthma

Asthma inflammatory phenotypes on four continents: most asthma is non-eosinophilic

BACKGROUND

Most studies assessing pathophysiological heterogeneity in asthma have been conducted in high-income countries (HICs), with little known about the prevalence and characteristics of different asthma inflammatory phenotypes in low-and middle-income countries (LMICs). This study assessed sputum inflammatory phenotypes in five centres, in Brazil, Ecuador, Uganda, New Zealand (NZ) and the United Kingdom (UK).

METHODS

We conducted a cross-sectional study of 998 asthmatics and 356 non-asthmatics in 2016-20. All centres studied children and adolescents (age range 8-20 years), except the UK centre which involved 26-27 year-olds. Information was collected using questionnaires, clinical characterization, blood and induced sputum.

RESULTS

Of 623 asthmatics with sputum results, 39% (243) were classified as eosinophilic or mixed granulocytic, i.e. eosinophilic asthma (EA). Adjusted for age and sex, with NZ as baseline, the UK showed similar odds of EA (odds ratio 1.04, 95% confidence interval 0.37-2.94) with lower odds in the LMICs: Brazil (0.73, 0.42-1.27), Ecuador (0.40, 0.24-0.66) and Uganda (0.62, 0.37-1.04). Despite the low prevalence of neutrophilic asthma in most centres, sputum neutrophilia was increased in asthmatics and non-asthmatics in Uganda.

CONCLUSIONS

This is the first time that sputum induction has been used to compare asthma inflammatory phenotypes in HICs and LMICs. Most cases were non-eosinophilic, including in settings where corticosteroid use was low. A lower prevalence of EA was observed in the LMICs than in the HICs. This has major implications for asthma prevention and management, and suggests that novel prevention strategies and therapies specifically targeting non-eosinophilic asthma are required globally.

Exhaled nitric oxide in chronic cough: A good tool in a multi-step approach

INTRODUCTION

The impact of fractional exhaled nitric oxide (FENO) on the management of chronic cough (CC) is still inconclusive. The aim of the present study was to assess whether FENO is a good tool to predict the response to inhaled corticosteroids (ICS) in patients with CC.

METHODS

Patients, referred for investigation of CC, had a FENO measurement determined as part of their first-line assessment. A methacholine test was performed as part of a second-line assessement. Patients were assigned to two groups according to their FENO values: a high FENO level group (Ⱕ25 ppb) and a normal FENO level group (<25 ppb).

RESULTS

One hundred patients were included in the study. High FENO levels were found in 25 patients (25%). The proportion of patients who responded to ICS was significantly greater in the high FENO group compared to the normal FENO level group (86.4% vs 46.3%, P<0.05). FENO is a good tool to predict ICS response in patients with high FENO levels but a response to ICS cannot be ruled out in patients with normal FENO levels. In patients with normal FENO values, a methacholine test could be an interesting tool for a second-line assessment. Among the 13 patients with a positive methacholine test result, 11 responded to ICS whilst 2 did not. Of the patients with a negative methacholine test result, 3 responded to ICS whilst 13 did not.

CONCLUSION

FENO may be a more reliable predictor of ICS response when used as part of a multi-step assessment procedure.

Determinants Of Oral corticosteroid Responsiveness in Wheezing Asthmatic Youth (DOORWAY): protocol for a prospective multicentre cohort study of children with acute moderate-to-severe asthma exacerbations

INTRODUCTION

Oral corticosteroids are the cornerstone of acute asthma management in the emergency department. Recent evidence has raised doubts about the efficacy of this treatment in preschool-aged children with viral-induced wheezing and in smoking adults. The aims of the study were to: (1) document the magnitude of response to oral corticosteroids in children presenting to the emergency department with moderate or severe asthma; (2) quantify potential determinants of response to corticosteroids and (3) explore the role of gene polymorphisms associated with the responsiveness to corticosteroids.

METHODS AND ANALYSIS

The design is a prospective cohort study of 1008 children aged 1-17 years meeting a strict definition of asthma and presenting with a clinical score of ≥4 on the validated Pediatric Respiratory Assessment Measure. All children will receive standardised severity-specific treatment with prednisone/prednisolone and cointerventions (salbutamol with/without ipratropium bromide). Determinants, namely viral aetiology, environmental tobacco smoke and single nucleotide polymorphism, will be objectively documented. The primary efficacy endpoint is the failure of emergency department (ED) management within 72 h of the ED visit. Secondary endpoints include other measures of asthma severity and time to recovery within 7 days of the index visit. The study has 80% power for detecting a risk difference of 7.5% associated with each determinant from a baseline risk of 21%, at an α of 0.05.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from all participating institutions. An impaired response to systemic steroids in certain subgroups will challenge the current standard of practice and call for the immediate search for better approaches. A potential host-environment interaction will broaden our understanding of corticosteroid responsiveness in children. Documentation of similar effectiveness of corticosteroids across determinants will provide the needed reassurance regarding current treatment recommendations.

RESULTS

Results will be disseminated at international conferences and manuscripts targeted at emergency physicians, paediatricians, geneticists and respirologists.

TRIAL REGISTRATION NUMBER

This study is registered at Clinicaltrials.gov (NCT02013076).

Interleukin-6 via sputum induction as biomarker of inflammation for indoor particulate matter among primary school children in Klang Valley, Malaysia

In the last few years, air within homes have been indicates by various and emerging body as more serious polluted than those outdoor. Prevalence of respiratory inflammation among school children aged 8 and 10 years old attending national primary schools in urban and rural area were conducted in Klang Valley. Two population studies drawn from the questionnaires were used to investigate the association between indoor particulate matter (PM_2.5 & PM₁₀) in a home environment and respiratory implication through the understanding of biological responses. Approximately 430 healthy school children of Standard 2 and Standard 5 were selected. Indication of respiratory symptoms using adaptation questionnaire from American Thoracic Society (1978). Sputum sample collection taken for biological analysis. IL-6 then was analyse by using ELISA techniques. Indoor PM_2.5 and PM₁₀ were measured using Dust Trak Aerosol Monitor. The mean concentration of PM_2.5 (45.38 µg/m³) and PM₁₀ (80.07 µg/m³) in urban home environment is significantly higher compared to those in rural residential area (p=0.001). Similar trend also shows by the prevalence of respiratory symptom. Association were found with PM_2.5 and PM₁₀ with the level of IL-6 among school children. A greater exposure to PM_2.5 and PM₁₀ are associated with higher expression of IL-6 level suggesting that the concentration of indoor particulate in urban density area significantly influence the health of children.

Biomarkers in asthma: a real hope to better manage asthma

Diagnosis and treatment of asthma are currently based on assessment of patient symptoms and physiologic tests of airway reactivity. Research over the past decade has identified an array of biochemical and cellular biomarkers, which reflect the heterogeneous and multiple mechanistic pathways that may lead to asthma. These mechanistic biomarkers offer hope for optimal design of therapies targeting the specific pathways that lead to inflammation. This article provides an overview of blood, urine, and airway biomarkers; summarizes the pathologic pathways that they signify; and begins to describe the utility of biomarkers in the future care of patients with asthma.

Autologous bone marrow mesenchymal stem cell therapy in the subacute stage of traumatic brain injury by lumbar puncture

OBJECTIVES

To explore the clinical therapeutic effects and safety of autologous bone marrow mesenchymal stem cell therapy for traumatic brain injury by lumbar puncture.

MATERIALS AND METHODS

A total of 97 patients (24 with persistent vegetative state and 73 with disturbance motor activity) who developed a complex cerebral lesion after traumatic brain injury received autologous bone marrow mesenchymal stem cell therapy voluntarily. The stem cells were isolated from the bone marrow of the patients and transplanted into the subarachnoid space by lumbar puncture.

RESULTS

Fourteen days after cell therapy, no serious complications or adverse events were reported. To a certain extent, 38 of 97 patients (39.2%) improved in the function of brain after transplant (P = .007). Eleven of 24 patients (45.8%) with persistent vegetative state showed posttherapeutic improvements in consciousness (P = .024). Twenty-seven of 73 patients (37.0%) with a motor disorder began to show improvements in motor functions (P = .025). The age of patients and the time elapsed between injury and therapy had effects on the outcomes of the cellular therapy (P < .05). No correlation was found between the number of cell injections and improvements (P > .05).

CONCLUSIONS

This study suggests that the bone marrow stem cell therapy is safe and effective on patients with traumatic brain injury complications, such as persistent vegetative state and motor disorder, through lumbar puncture. Young patients improve more easily than older ones. The earlier the cellular therapy begins in the subacute stage of traumatic brain injury, the better the results.

Asthma outcomes: biomarkers

BACKGROUND

Measurement of biomarkers has been incorporated within clinical research studies of asthma to characterize the population and associate the disease with environmental and therapeutic effects.

OBJECTIVE

National Institutes of Health institutes and federal agencies convened an expert group to propose which biomarkers should be assessed as standardized asthma outcomes in future clinical research studies.

METHODS

We conducted a comprehensive search of the literature to identify studies that developed and/or tested asthma biomarkers. We identified biomarkers relevant to the underlying disease process progression and response to treatment. We classified the biomarkers as either core (required in future studies), supplemental (used according to study aims and standardized), or emerging (requiring validation and standardization). This work was discussed at an National Institutes of Health-organized workshop convened in March 2010 and finalized in September 2011.

RESULTS

Ten measures were identified; only 1, multiallergen screening to define atopy, is recommended as a core asthma outcome. Complete blood counts to measure total eosinophils, fractional exhaled nitric oxide (Feno), sputum eosinophils, urinary leukotrienes, and total and allergen-specific IgE are recommended as supplemental measures. Measurement of sputum polymorphonuclear leukocytes and other analytes, cortisol measures, airway imaging, breath markers, and system-wide studies (eg, genomics, proteomics) are considered as emerging outcome measures.

CONCLUSION

The working group participants propose the use of multiallergen screening in all asthma clinical trials to characterize study populations with respect to atopic status. Blood, sputum, and urine specimens should be stored in biobanks, and standard procedures should be developed to harmonize sample collection for clinical trial biorepositories.

Sputum dipalmitoylphosphatidylcholine level as a novel airway inflammatory marker in asthmatic children

INTRODUCTION

Pulmonary surfactant is a unique mixture of lipids and surfactant-specific proteins. Phosphatidylcholine comprises almost 80% of the total surfactant lipids, about half of which is dipalmitoylphosphatidylcholine (DPPC). Alteration of surfactant composition and function is documented with various airway or lung parenchyma disorders.

OBJECTIVE

To assess sputum concentration of DPPC as a major component of airways surfactant in asthmatic children compared to conventional airway inflammatory markers.

METHODS

This case control study included 68 well-known asthmatic children of different grades of severity and 20 age- and sex-matched normal children as controls. All children were subjected to thorough clinical examination, pulmonary function tests, sputum induction and processing for cytology, DPPC level and eosinophil cationic protein (ECP) level assessment.

RESULTS

Elevated DPPC levels were evident in all sputum samples of asthmatic children (mean value 626.6 +/- 189.7 mcg/mL) compared to controls (mean value 49.3 +/- 20.1 mcg/mL). Significant negative correlations (r = -0.83, -0.752 and -0.384) were found between asthmatics sputum DPPC levels and pulmonary function test parameters [% of forced expiratory volume in first second, % of forced vital capacity (FVC) and forced expiratory flow rate over 25%-75% part of FVC], respectively. Meanwhile, significant positive correlations were evident between asthmatics sputum DPPC levels and the sputum inflammatory cells and their sputum ECP levels.

CONCLUSION

Elevated DPPC levels are evident in induced sputum of all asthmatic children and they are significantly related to sputum ECP levels and pulmonary function test parameters. Nevertheless, the value of DPPC estimation in the clinical management of children with asthma remains to be determined.

Fiber-optic microsphere-based antibody array for the analysis of inflammatory cytokines in saliva

Antibody microarrays have emerged as useful tools for high-throughput protein analysis and candidate biomarker screening. We describe here the development of a multiplexed microsphere-based antibody array capable of simultaneously measuring 10 inflammatory protein mediators. Cytokine-capture microspheres were fabricated by covalently coupling monoclonal antibodies specific for cytokines of interest to fluorescently encoded 3.1 microm polymer microspheres. An optical fiber bundle containing approximately 50,000 individual 3.1 microm diameter fibers was chemically etched to create microwells in which cytokine-capture microspheres could be deposited. Microspheres were randomly distributed in the wells to produce an antibody array for performing a multiplexed sandwich immunoassay. The array responded specifically to recombinant cytokine solutions in a concentration-dependent fashion. The array was also used to examine endogenous mediator patterns in saliva supernatants from patients with pulmonary inflammatory diseases such as asthma and chronic obstructive pulmonary disease (COPD). This array technology may prove useful as a laboratory-based platform for inflammatory disease research and diagnostics, and its small footprint could also enable integration into a microfluidic cassette for use in point-of-care testing.

Urinary eosinophil protein X in children with atopic asthma

The aim of this study was to investigate the relationship between urinary eosinophil protein X (uEPX) and asthma symptoms, lung function, and other markers of eosinophilic airway inflammation in asthmatic school children.

METHODS

A cross-sectional study was performed in 180 steroid dependent atopic children with stable moderately severe asthma, who were stable on 200 or 500 microg of fluticasone per day. uEPX was measured in a single sample of urine and was normalized for creatinine concentration (uEPX/c). Symptom scores were kept on a diary card. FEV1 and PD20 methacholine were measured. Sputum induction was performed in 49 and FE(NO) levels measured in 24 children.

RESULTS

We found an inverse correlation between uEPX/c and FEV1 (r = -.20, P = .01) and a borderline significant correlation between uEPX/c and PD20 methacholine (r = -.15, P = .06). Symptom score, %eosinophils and ECP in induced sputum and FE(NO) levels did not correlate with uEPX/c.

CONCLUSION

uEPX/c levels did not correlate with established markers of asthma severity and eosinophilic airway inflammation in atopic asthmatic children.

Exhaled nitric oxide for monitoring childhood asthma inflammation compared to sputum analysis, serum interleukins and pulmonary function

The level of fractional exhaled nitric oxide (FENO) is significantly elevated in uncontrolled asthma and decreases after anti-inflammatory therapy. The aim of this prospective study was to analyze the behavior of FENO in the follow-up and management of the inflammation in asthmatic pediatric patients treated with inhaled corticosteroids (ICS), compared to sputum cellularity, serum interleukins (IL), and pulmonary function. Twenty-six clinically stable asthmatic children aged from 6 to 18 years, previously treated or not with ICS were included. Following an international consensus (GINA), the patients were submitted to standard treatment with inhaled fluticasone for 3 months according to the severity of the disease. During this period, each patient underwent three assessments at intervals of approximately 6 weeks. Each evaluation consisted of the measurement of FENO, determination of serum interleukins IL-5, IL-10, IL-13, and interferon gamma (INF-gamma), spirometry and cytological analysis of spontaneous or induced sputum. A significant reduction in mean FENO and IL-5, without concomitant changes in FEV1, was observed along the study. There was no significant correlation between FeNO and FEV1 in the three assessments. A significant correlation between FeNO and IL-5 levels was only observed in the third assessment (r = 0.499, P = 0.025). In most patients, serum IL-10, IL-13, and INF-gamma concentrations were undetectable throughout the study. Sputum samples were obtained spontaneously in 11 occasions and in 56 by induction with 3% hypertonic saline solution (success rate: 50.8%), with 39 (69.9%) of them adequate for analysis. Only two of the 26 patients produced adequate samples in the three consecutive evaluations, which impaired the determination of a potential association between sputum cellularity and FeNO levels throughout the study. In conclusion, among the parameters of this study, it was difficult to perform and to interpret the serial analysis of spontaneous or induced sputum. Serum interleukins, which remained at very low or undetectable levels in most patients, were not found to be useful for therapeutic monitoring, except for IL-5 that seems to present some correlation with levels of FeNO exhaled. Monitoring of the mean FEV1 indicated no significant variations during the treatment, demonstrating that functional stability or the absence of obstruction may not reflect the adequate management of asthma. Serial measurement of FeNO seemed to best reflect the progressive anti-inflammatory action of ICS in asthma.

Clinical use of noninvasive measurements of airway inflammation in steroid reduction in children

The use of noninvasive methods of monitoring airway inflammation, such as exhaled nitric oxide (eNO) and induced sputum, has been shown to improve asthma monitoring and optimize treatment in adult patients with asthma. There is a lack of comparable data in children. Forty children with stable asthma eligible for inhaled steroid reduction were reviewed every 8 weeks, and their inhaled steroid dose halved if clinically indicated. eNO, sputum induction combined with bronchial hyperreactivity testing, and exhaled breath condensate collection were performed at each visit to predict success or failure of reduction of inhaled steroids. Thirty of 40 (75%) children tolerated at least one dose reduction, 12 of 40 (30%) were successfully weaned off, and in total, 15 of 40 (38%) children experienced loss of asthma control. Treatment reduction was successful in all children who had no eosinophils in induced sputum before the attempted reduction. Using multiple logistic regression, increased eNO (odds ratio, 6.3; confidence interval, 3.75-10.58) and percentage of sputum eosinophils (odds ratio, 1.38; confidence interval, 1.06-1.81) were significant predictors of failed reduction. These findings suggest that monitoring airway inflammation may be useful in optimizing treatment in children with asthma.

Airway inflammation in asthma with incomplete reversibility of airflow obstruction

This study aimed to determine whether there is a persistent or different type of airway inflammation in patients with an incomplete reversibility of airflow obstruction (IRAO) despite optimal treatment and if so, whether it is associated with an accelerated decline of pulmonary function. Fifteen asthmatic patients with IRAO, and 23 with complete reversibility of airflow obstruction (CRAO) had a spirometry and an induced-sputum (IS) analysis. Past FEV1 values were recorded over 2-12 years during periods of stable asthma. Medians (range) for IS cell differentials were: lymphocytes, 0(0-3)/1(0-2)%; neutrophils, 56(13-88)/38(3-84)% and eosinophils, 2.0(0-82)/4.0(0-68)%, (all P>0.05). Among non-smoking patients, those with IRAO had more neutrophils in IS than those with CRAO (P=0.019). Mean (+/-SEM) yearly fall in FEV1 in IRAO or CRAO patients was 54+/-21/84+/-16 ml/year (P>0.05, predicted age-related decline < or = 26 ml/year, P=0.0008). In the whole group of asthmatic patients, decline of FEV1/year was inversely correlated with the % neutrophils in sputum (r(s)=-0.436, P=0.008) and, in IRAO patients, with the duration of asthma (r(s)=-0.559, P=0.037). In conclusion, persistent airway inflammation and increased decline in pulmonary function can be observed in both asthmatic patients with IRAO/CRAO and are of similar magnitude. Non-smoking patients with IRAO had more neutrophils in IS than CRAO.

The relationship between inflammation and dipalmitoyl phosphatidycholine in induced sputum of children with asthma

BACKGROUND

Animal studies have shown elevated surfactant production in response to lung injury. In human airways, the contribution of surfactant to the airway epithelial barrier and importance of eosinophilic inflammation is increasingly appreciated. The relationship between blood and sputum inflammatory indices of childhood asthma to surfactant levels is unknown. In this study we hypothesized that the degree of inflammation influences the level of dipalmitoyl phosphatidycholine (DPPC) in airways of children with asthma.

METHODS

Sixteen children with asthma (ages 5.5-16 years) underwent venipuncture, skin prick test, spirometry, hypertonic saline challenge, and induced sputum during a nonacute phase. Sputum (sp) and blood (se) markers of inflammation (eosinophils, neutrophils, eosinophilic cationic protein [ECP]), were related to sputum DPPC levels and several markers of asthma severity (airway hyperresponsiveness, quality of life, FEV1).

RESULTS

On multiple regression, sp-DPPC significantly correlated to sp-ECP (r=0.53, P=0.0048). Se-ECP, se-Eo, sp-eosinophils, sp-neutrophils, se-neutrophils, and inhaled steroids dose did not significantly influence sp-DPPC. Exposure to smoke did not influence inflammatory markers. FEV1 and quality of life data did not relate to any blood or sputum variable. A significant association between AHR and se-eosinophils, but not between AHR and se-ECP, sp-eosinophils, or sp-ECP was found.

CONCLUSION

Elevated DPPC levels occur in the presence of chronic eosinophilic inflammation in airways of children with stable asthma. Whether this represents an inherent lung mechanism for epithelial protection remains to be elucidated.

Non-invasive monitoring of airway inflammation

What we know: Various techniques are available that purport to measure aspects of airway inflammation non-invasively, including analysis of volatile molecules in exhaled breath and components of breath condensates. Adapting and validating these methods for use in young children and infants poses significant methodological problems, but progress has been made, particularly with regard to measurements of exhaled nitric oxide. Future studies to validate such tests are likely to require access to airway tissue for examination as a "gold standard". What we need to know: How can we obtain airway tissue from infants and young children to better characterise the early airway changes in asthma? How do non-invasive tests of airway inflammation compare with a validated gold standard? How sensitive and specific are non-invasive tests of inflammation for predicting outcomes in asthma, including response to therapy?

Non-eosinophilic asthma: importance and possible mechanisms

There is increasing evidence that inflammatory mechanisms other than eosinophilic inflammation may be involved in producing the final common pathway of enhanced bronchial reactivity and reversible airflow obstruction that characterises asthma. A review of the literature has shown that, at most, only 50% of asthma cases are attributable to eosinophilic airway inflammation. It is hypothesised that a major proportion of asthma is based on neutrophilic airway inflammation, possibly triggered by environmental exposure to bacterial endotoxin, particulate air pollution, and ozone, as well as viral infections. If there are indeed two (or more) subtypes of asthma, and if non-eosinophilic (neutrophil mediated) asthma is relatively common, this would have major consequences for the treatment and prevention of asthma since most treatment and prevention strategies are now almost entirely focused on allergic/eosinophilic asthma and allergen avoidance measures, respectively. It is therefore important to study the aetiology of asthma further, including the underlying inflammatory profiles.

Clinical significance of bronchoalveolar eosinophils in childhood asthma

To evaluate the relationship between clinical parameters and differential cell counts, bronchoalveolar lavage was performed in 79 asthmatic infants and children with unusual asthma. Multivariate analysis showed significant associations between (1) allergic asthma and the presence of alveolar eosinophils and (2) persistent and longer asthma and an increased number of alveolar neutrophils. Our results provide the first evidence that in asthmatic infants and children eosinophilic inflammation is related to allergic sensitization.