Blood granulocyte patterns as predictors of asthma phenotypes in adults from the EGEA study

Sex differences in asthma control, lung function and exacerbations: the ATLANTIS study

BACKGROUND

Asthma is a heterogeneous disease with a prevalence and severity that differs between male and female patients.

QUESTION

What are differences between male and female patients with asthma with regard to asthma control, lung function, inflammation and exacerbations?

METHODS

We performed a post hoc analysis in the ATLANTIS (Assessment of Small Airways Involvement in Asthma) study, an observational cohort study including patients with asthma from nine countries with a follow-up of 1 year during which patients were characterised with measures of large and small airway function, questionnaires, inflammation and imaging. We compared differences in baseline characteristics and longitudinal outcomes between male and female patients with asthma.

RESULTS

773 patients were enrolled; 450 (58%) of these were female. At baseline, female patients with asthma were in higher Global Initiative for Asthma (GINA) steps (p=0.042), had higher Asthma Control Questionnaire 6 (F: 0.83; M: 0.66, p<0.001) and higher airway resistance as reflected by uncorrected impulse oscillometry outcomes (ie, R5-R20: F: 0.06; M: 0.04 kPa/L/s, p=0.002). Male patients with asthma had more severe airway obstruction (forced expiratory volume in 1 s/forced vital capacity % predicted: F: 91.95; M: 88.33%, p<0.01) and more frequently had persistent airflow limitation (F: 27%; M: 39%, p<0.001). Blood neutrophils were significantly higher in female patients (p=0.014). With Cox regression analysis, female sex was an independent predictor for exacerbations.

INTERPRETATION

We demonstrate that female patients are in higher GINA steps, exhibit worse disease control, experience more exacerbations and demonstrate higher airway resistance compared with male patients. The higher exacerbation risk was independent of GINA step and blood eosinophil level. Male patients, in turn, have a higher prevalence of persistent airflow limitation and more severe airflow obstruction. These findings show sex can affect clinical phenotyping and outcomes in asthma.

TRIAL REGISTRATION NUMBER

NCT02123667.

Cluster analysis of phenotypes, job exposure, and inflammatory patterns in elderly and nonelderly asthma patients

BACKGROUND

Asthma has been identified as different phenotypes due to various risk factors. Age differences may have potential effects on asthma phenotypes. Our study aimed to identify potential asthma phenotypes among adults divided by age as either younger or older than 65 years. We also compared differences in blood granulocyte patterns, occupational asthmagens, and asthma control-related outcomes among patient phenotype clusters.

METHODS

We recruited nonelderly (<65 years old) (n = 726) and elderly adults (≥65 years old) (n = 201) with mild-to-severe asthma. We conducted a factor analysis to select 17 variables. A two-step cluster analysis was used to classify subjects with asthma phenotypes, and a discriminant analysis was used to verify the classification of cluster results.

RESULTS

There were three clusters with different characteristics identified in both the nonelderly and elderly asthmatic adults. In the nonelderly patient group, cluster 2 (obese, neutrophilic phenotypes) had a 1.85-fold significantly increased risk of asthma exacerbations. Cluster 3 (early-onset, atopy, and smoker with an eosinophil-predominant pattern) had a 2.37-fold risk of asthma exacerbations and higher oral corticosteroid (OCS) use than cluster 1 (late-onset and LMW exposure with paucigranulocytic blood pattern). Among elderly patients, cluster 2 had poor lung function and more ex-smokers. Cluster 3 (early-onset, long asthma duration) had the lowest paucigranulocytic blood pattern percentages in the elderly group.

CONCLUSIONS

The novelty of the clusters was found in age-dependent clusters. We identified three distinct phenotypes with heterogeneous characteristics, asthma exacerbations and medicine use in nonelderly and elderly asthmatic patients, respectively. Classification of age-stratified asthma phenotypes may lead to precise identification of patients, which provides personalized disease management.

Proteomic signatures of eosinophilic and neutrophilic asthma from serum and sputum

BACKGROUND

Eosinophilic and neutrophilic asthma defined by high levels of blood and sputum eosinophils and neutrophils exemplifies the inflammatory heterogeneity of asthma, particularly severe asthma. We analysed the serum and sputum proteome to identify biomarkers jointly associated with these different phenotypes.

METHODS

Proteomic profiles (N = 1129 proteins) were assayed in sputum (n = 182) and serum (n = 574) from two cohorts (U-BIOPRED and ADEPT) of mild-moderate and severe asthma by SOMAscan. Using least absolute shrinkage and selection operator (LASSO)-penalised logistic regression in a stability selection framework, we sought sparse sets of proteins associated with either eosinophilic or neutrophilic asthma with and without adjustment for established clinical factors including oral corticosteroid use and forced expiratory volume.

FINDINGS

We identified 13 serum proteins associated with eosinophilic asthma, including 7 (PAPP-A, TARC/CCL17, ALT/GPT, IgE, CCL28, CO8A1, and IL5-Rα) that were stably selected while adjusting for clinical factors yielding an AUC of 0.84 (95% CI: 0.83-0.84) compared to 0.62 (95% CI: 0.61-0.63) for clinical factors only. Sputum protein analysis selected only PAPP-A (AUC = 0.81 [95% CI: 0.80-0.81]). 12 serum proteins were associated with neutrophilic asthma, of which 5 (MMP-9, EDAR, GIIE/PLA2G2E, IL-1-R4/IL1RL1, and Elafin) complemented clinical factors increasing the AUC from 0.63 (95% CI: 0.58-0.67) for the model with clinical factors only to 0.89 (95% CI: 0.89-0.90). Our model did not select any sputum proteins associated with neutrophilic status.

INTERPRETATION

Targeted serum proteomic profiles are a non-invasive and scalable approach for subtyping of neutrophilic and eosinophilic asthma and for future functional understanding of these phenotypes.

FUNDING

U-BIOPRED has received funding from the Innovative Medicines Initiative (IMI) Joint Undertaking under grant agreement no. 115010, resources of which are composed of financial contributions from the European Union's Seventh Framework Programme (FP7/2007-2013), and European Federation of Pharmaceutical Industries and Associations (EFPIA) companies' in-kind contributions (www.imi.europa.eu). ADEPT was funded by Johnson & Johnson/Janssen pharmaceutical Company.

Phenotype overlap in the natural history of asthma

The heterogeneity of asthma makes it challenging to unravel the pathophysiologic mechanisms of the disease. Despite the wealth of research identifying diverse phenotypes, many gaps still remain in our knowledge of the disease's complexity. A crucial aspect is the impact of airborne factors over a lifetime, which often results in a complex overlap of phenotypes associated with type 2 (T2), non-T2 and mixed inflammation. Evidence now shows overlaps between the phenotypes associated with T2, non-T2 and mixed T2/non-T2 inflammation. These interconnections could be induced by different determinants such as recurrent infections, environmental factors, T-helper plasticity and comorbidities, collectively resulting in a complex network of distinct pathways generally considered as mutually exclusive. In this scenario, we need to abandon the concept of asthma as a disease characterised by distinct traits grouped into static segregated categories. It is now evident that there are multiple interplays between the various physiologic, cellular and molecular features of asthma, and the overlap of phenotypes cannot be ignored.

Delineating asthma according to inflammation phenotypes with a focus on paucigranulocytic asthma

ABSTRACT

Asthma is characterized by chronic airway inflammation and airway hyper-responsiveness. However, the differences in pathophysiology and phenotypic symptomology make a diagnosis of "asthma" too broad hindering individualized treatment. Four asthmatic inflammatory phenotypes have been identified based on inflammatory cell profiles in sputum: eosinophilic, neutrophilic, paucigranulocytic, and mixed-granulocytic. Paucigranulocytic asthma may be one of the most common phenotypes in stable asthmatic patients, yet it remains much less studied than the other inflammatory phenotypes. Understanding of paucigranulocytic asthma in terms of phenotypic discrimination, distribution, stability, surrogate biomarkers, underlying pathophysiology, clinical characteristics, and current therapies is fragmented, which impedes clinical management of patients. This review brings together existing knowledge and ongoing research about asthma phenotypes, with a focus on paucigranulocytic asthma, in order to present a comprehensive picture that may clarify specific inflammatory phenotypes and thus improve clinical diagnoses and disease management.

Association Between Blood Eosinophils and Neutrophils With Clinical Features in Adult-Onset Asthma

BACKGROUND

Asthma is a disease that can be separated into different phenotypes and endotypes based on the clinical characteristics and the molecular mechanisms of the condition, respectively.

OBJECTIVE

To assess the association between blood eosinophil and neutrophil counts with clinical and molecular features in patients with adult-onset asthma.

METHODS

Blood eosinophil and neutrophil counts were measured from 203 patients who took part in the Seinäjoki Adult Asthma Study and attended the 12-year follow-up visit. The patients were then divided into four groups (paucigranulocytic [n = 108], neutrophilic [n = 60], eosinophilic [n = 21], and mixed granulocytic [n = 14]), according to eosinophil and neutrophil levels. The cutoff values used to define the groups were 0.30 × 10⁹ · L^-1 for blood eosinophils and 4.4 × 10⁹ · L^-1 for blood neutrophils.

RESULTS

The neutrophilic group had highest body mass index. It was dispensed the highest doses of inhaled corticosteroids during the 12-year follow-up and made the most unplanned respiratory visits. The neutrophilic, eosinophilic, and mixed granulocytic groups had more severe asthma compared with the paucigranulocytic group. The neutrophilic and eosinophilic groups were associated with higher dispensed antibiotics. The eosinophilic group had more nasal polyps, more suspected sinusitis, a greater decline in lung function, and increased levels of periostin, FeNO, and IgE. The neutrophilic group had increased high-sensitivity C-reactive protein, matrix metalloproteinase-9, IL-6, leptin, and soluble urokinase plasminogen activator receptor levels. The mixed granulocytic group showed increased resistin levels together with the neutrophilic group.

CONCLUSIONS

In addition to blood eosinophils, the blood neutrophil count reflects underlying inflammatory patterns and indicates important differences in asthma clinical features and outcomes.

Comparison between clinical trials and real-world evidence studies on biologics for severe asthma

In recent years, the more widespread availability of biological drugs with specific mechanisms of action has led to significant breakthroughs in the management of severe asthma. Over time, numerous randomised clinical trials have been conducted to evaluate the efficacy and safety of these biologics and define the eligibility criteria of patients suitable for various therapeutic options. These studies were conducted under controlled conditions not always applicable to real life. For this and other reasons, real-world evidence and pragmatic studies are required to provide useful information on the effectiveness of biological drugs and their safety, even in the long term. Because differences in outcomes have sometimes emerged between clinical trials and real-life studies, it is important to clarify the causes of these discrepancies and define the significance of the results of studies conducted in the course of daily clinical practice. Thus, a scientific debate is ongoing, and no consensus has been reached. The purpose of this narrative review is to analyse the differences between randomised trials and real-world evidence studies, focusing on their roles in guiding clinicians among different therapeutic options and understanding the reasons for the large discrepancies often found in the results obtained.

Selected hematological abnormalities and their associated factors among asthmatic patients in Northwest Ethiopia: a cross-sectional study

Background

Asthma is a chronic inflammatory disease that affects the lungs. Variation in whole blood cell lines is caused by the progression and severity of asthma. Common hematological abnormalities encountered during asthma include eosinophilia, neutrophilia, leukocytosis, and increased erythrocyte sedimentation rate. The main aim of this study was to assess the selected hematological abnormalities and their associated factors among asthmatic patients in Northwest Ethiopia from March to May 2021.

Methodology

A hospital-based cross-sectional study was conducted on a total of 320 asthmatic patients in Northwest Ethiopia. A simple random sampling technique was employed to select study participants. A pre-tested structured questionnaire and a checklist were used to collect data. Blood samples were collected from asthmatic patients for complete blood count and erythrocyte sedimentation rate determination. Hematological profiles were analyzed by Unicel DxH 800 (Beckman Coulter, Ireland). The erythrocyte sedimentation rate was determined by using the Westergren method. The data were entered into EpiData version 3.0.4 and analyzed with a statistical package for social science version 20 software. The bi-variable and multi-variable binary logistic regression models were used to assess the factors associated with hematological abnormalities. A p value of less than 0.05 in the multivariable logistic regression analysis was considered statistically significant.

Results

The overall prevalence of neutrophilia, eosinophilia, thrombocytopenia, leukocytosis, and basophilia was 35.3%, 20%, 11.9%, 10.3%, and 4.1%, respectively. Neutrophilia was associated with a lack of physical activity (AOR = 3.25; 95% CI 1.43–7.37) and a history of taking non-asthmatic drugs within the previous three months (AOR = 2.63; 95% CI 1.22–5.65). Being admitted to the emergency department (AOR = 0.27; 95% CI 0.11–5.67) was found to be associated with eosinophilia. In addition, being admitted to the emergency department (AOR = 5.44; 95%CI: 2.6–11.3) was associated with thrombocytopenia.

Conclusion

The current study demonstrated the predominant prevalence of neutrophilia, followed by eosinophilia, among asthma patients. Therefore, hematological abnormalities should be taken into account for proper monitoring and management of asthmatic patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02020-z.

Genome-Wide Association Study of Fluorescent Oxidation Products Accounting for Tobacco Smoking Status in Adults from the French EGEA Study

Oxidative stress (OS) is the main pathophysiological mechanism involved in several chronic diseases, including asthma. Fluorescent oxidation products (FlOPs), a global biomarker of damage due to OS, is of growing interest in epidemiological studies. We conducted a genome-wide association study (GWAS) of the FlOPs level in 1216 adults from the case-control and family-based EGEA study (mean age 43 years old, 51% women, and 23% current smokers) to identify genetic variants associated with FlOPs. The GWAS was first conducted in the whole sample and then stratified according to smoking status, the main exogenous source of reactive oxygen species. Among the top genetic variants identified by the three GWAS, those located in BMP6 (p = 3 × 10⁻⁶), near BMPER (p = 9 × 10⁻⁶), in GABRG3 (p = 4 × 10⁻⁷), and near ATG5 (p = 2 × 10⁻⁹) are the most relevant because of both their link to biological pathways related to OS and their association with several chronic diseases for which the role of OS in their pathophysiology has been pointed out. BMP6 and BMPER are of particular interest due to their involvement in the same biological pathways related to OS and their functional interaction. To conclude, this study, which is the first GWAS of FlOPs, provides new insights into the pathophysiology of chronic OS-related diseases.

Blood inflammatory phenotypes were associated with distinct clinical expressions of asthma in adults from a large population-based cohort

BACKGROUND

Asthma is an inflammatory heterogeneous disease. Asthma inflammatory phenotypes based on blood eosinophil and neutrophil counts have never been identified and characterized in population-based studies.

METHODS

Adults with current asthma and available blood eosinophil and neutrophil counts from the French population-based CONSTANCES cohort were included. Current asthma was defined by reports of asthma attacks, symptoms or treatments in the last 12 months. Inflammatory phenotypes were based on low (L) and high (H) blood (B) eosinophil (E) (LBE/HBE:

FINDINGS

Among 15,019 adults with asthma (56% women, 59%≥40 years), the LBE/LBN (reference), LBE/HBN, HBE/LBN and HBE/HBN phenotypes accounted for 57%, 6%, 33% and 4% respectively. The LBE/HBN phenotype was associated with being awaken by an attack of coughing, chronic bronchitis, and dyspnoea (adjusted(a)OR ranging from 1·21 to 1·42). The HBE/LBN and HBE/HBN phenotypes were associated with asthma attacks (aOR=1·31[1·20-1·42], 1·25[1·02-1·53]) and asthma symptom score (p for trend<0·0001, p for trend=0·001, respectively). The HBE/LBN phenotype was also associated with being awaken with chest tightness (aOR=1·30[1·20-1·40]). Results were unchanged whatever the cut-offs used. No statistically significant heterogeneity was observed according to age or sex.

INTERPRETATION

Differences in the clinical expressions of asthma were found between the phenotypes, reproducible whatever the cut-offs used, and similar to those observed in case-control and clinical studies. Such phenotypes are of interest to improve asthma management and study its environmental risk factors.

FUNDING

The CONSTANCES cohort receives grants from ANR (ANR-11-INBS-0002), the Caisse nationale d'assurance maladie-CNAM and the Ministry of research. CONSTANCES also receives funding from MSD, AstraZeneca, Lundbeck and L'Oréal, managed by INSERM-Transfert. T.Tsiavia is supported by a PhD grant from the Fondation pour le Recherche Médicale (ECO202006011654).

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Key Words

• Adults
• Asthma
• Blood
• Eosinophil
• Inflammation
• Neutrophil
• Phenotype

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MESH Headings

• Asthma
• Eosinophils
• Female
• Humans
• Leukocyte Count
• Male
• Neutrophils/metabolism
• Phenotype

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Affiliation(s)

Tajidine Tsiavia Université Paris-Saclay, UVSQ, Univ. Paris-Sud, Inserm, Équipe d'Épidémiologie Respiratoire Int´grative, CESP, 94807, Villejuif, France.
Joseph Henny Université Paris-Saclay, UVSQ, Inserm, Cohortes Epidémiologiques en population, 94807, Villejuif, France
Marcel Goldberg Université Paris-Saclay, UVSQ, Inserm, Cohortes Epidémiologiques en population, 94807, Villejuif, France; Faculté de Médecine, Univ. de Paris, Paris, France
Marie Zins Université Paris-Saclay, UVSQ, Inserm, Cohortes Epidémiologiques en population, 94807, Villejuif, France; Faculté de Médecine, Univ. de Paris, Paris, France
Nicolas Roche Université Paris-Saclay, UVSQ, Univ. Paris-Sud, Inserm, Équipe d'Épidémiologie Respiratoire Int´grative, CESP, 94807, Villejuif, France; Respiratory Medicine, Pneumologie et Soins Intensifs Respiratoires, APHP Centre, Cochin Hospital, Université de Paris (Descartes), Institut Cochin (UMR 1016), Paris, France
Laurent Orsi Université Paris-Saclay, UVSQ, Univ. Paris-Sud, Inserm, Équipe d'Épidémiologie Respiratoire Int´grative, CESP, 94807, Villejuif, France
Rachel Nadif Université Paris-Saclay, UVSQ, Univ. Paris-Sud, Inserm, Équipe d'Épidémiologie Respiratoire Int´grative, CESP, 94807, Villejuif, France

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Blood eosinophil counts in the general population and airways disease: a comprehensive review and meta-analysis

BACKGROUND

The clinical context for using blood eosinophil (EOS) counts as treatment-response biomarkers in asthma and COPD requires better understanding of EOS distributions and ranges. We describe EOS distributions and ranges published in asthma, COPD, control (non-asthma/COPD) and general populations.

METHODS

We conducted a comprehensive literature review and meta-analysis of observational studies (January 2008 to November 2018) that included EOS counts in asthma, severe asthma, COPD, control and general populations. Excluded studies had total sample sizes <200, EOS as inclusion criterion, hospitalised population only and exclusively paediatric participants.

RESULTS

Overall, 91 eligible studies were identified, most had total-population-level data available: asthma (39 studies), severe asthma (12 studies), COPD (23 studies), control (seven studies) and general populations (14 studies); some articles reported data for multiple populations. Reported EOS distributions were right-skewed (seven studies). Reported median EOS counts ranged from 157-280 cells·µL-1 (asthma, 22 studies); 200-400 cells·µL-1 (severe asthma, eight studies); 150-183 cells·µL-1 (COPD, six studies); and 100-160 cells·µL-1 (controls, three studies); and 100-200 cells·µL-1 (general populations, six studies). The meta-analysis showed that observed variability was mostly between studies rather than within studies. Factors reportedly associated with higher blood EOS counts included current smoking, positive skin-prick test, elevated total IgE, comorbid allergic rhinitis, age ≤18 years, male sex, spirometric asthma/COPD diagnosis, metabolic syndrome and adiposity.

CONCLUSION

EOS distribution and range varied by study population, and were affected by clinical factors including age, smoking history and comorbidities, which, regardless of severity, should be considered during treatment decision-making.

Which Therapy for Non-Type(T)2/T2-Low Asthma

Currently, the asthmatic population is divided into Type 2-high and non-Type 2/Type 2-low asthmatics, with 50% of patients belonging to one of the two groups. Differently from T2-high, T2-low asthma has not been clearly defined yet, and the T2-low patients are identified on the basis of the absence or non-predominant expression of T2-high biomarkers. The information about the molecular mechanisms underpinning T2-low asthma is scarce, but researchers have recognized as T2-low endotypes type 1 and type 3 immune response, and remodeling events occurring without inflammatory processes. In addition, the lack of agreed biomarkers reprents a challenge for the research of an effective therapy. The first-choice medication is represented by inhaled corticosteroids despite a low efficacy is reported for/in T2-low patients. However, macrolides and long-acting anti-muscarinic drugs have been recognized as efficacious. In recent years, clinical trials targeting biomarkers playing key roles in T3 and T1 immune pathways, alarmins, and molecules involved in neutrophil recruitment have provided conflicting results probably misleading (or biased) in patients' selection. However, further studies are warranted to achieve a precise characterization of T2-low asthma with the aim of defining a tailored therapy for each single asthmatic patient.

Bronchial Thermoplasty in Severe Asthmatics At 5 Years: The PAS2 Study

BACKGROUND

Bronchial thermoplasty is a device-based treatment for subjects ≥18 years with severe asthma poorly controlled with inhaled corticosteroids and long-acting beta-agonists. The Post-FDA Approval Clinical Trial Evaluating Bronchial Thermoplasty in Severe Persistent Asthma (PAS2) study collected data on severe asthmatics undergoing this procedure.

RESEARCH QUESTION

What are the 5-year efficacy and safety results in severe asthmatics who have undergone bronchial thermoplasty?

STUDY DESIGN AND METHODS

This was a prospective, open-label, observational, multi-center study conducted in the United States and Canada. Subjects aged 18-65, taking inhaled corticosteroids ≥1000μg/day (beclomethasone or equivalent) and long-acting β-agonists ≥80μg/day (salmeterol or equivalent) were included. Severe exacerbations, hospitalization, emergency department visits, and medication usage were evaluated for the 12 months prior to and at years 1-5 post-treatment. Spirometry was evaluated at baseline and at years 1-5 post-treatment.

RESULTS

284 subjects were enrolled at 27 centers; 227 subjects (80%) completed 5 years of follow-up. By year 5 post-treatment, the proportion of subjects with severe exacerbations, emergency department visits, and hospitalizations was 42.7%, 7.9%, and 4.8%, respectively, compared to 77.8%, 29.4%, and 16.1% in the 12 months prior to treatment. The proportion of subjects on maintenance oral corticosteroids decreased from 19.4% at baseline to 9.7% at 5 years. Analyses of subgroups based on baseline clinical and biomarker characteristics revealed a statistically significant clinical improvement among all subgroups.

INTERPRETATION

Five years after treatment, subjects experienced decreases in severe exacerbations, hospitalizations, emergency department visits and corticosteroid exposure. All subgroups demonstrated clinically significant improvement, suggesting that bronchial thermoplasty improves asthma control in different asthma phenotypes.

A unique population of neutrophils generated by air pollutant-induced lung damage exacerbates airway inflammation

BACKGROUND

Diesel exhaust particles (DEPs) are the main component of traffic-related air pollution and have been implicated in the pathogenesis and exacerbation of asthma. However, the mechanism by which DEP exposure aggravates asthma symptoms remains unclear.

OBJECTIVE

This study aimed to identify a key cellular player of air pollutant-induced asthma exacerbation and development.

METHODS

We examined the distribution of innate immune cells in the murine models of asthma induced by house dust mite and DEP. Changes in immune cell profiles caused by DEP exposure were confirmed by flow cytometry and RNA-Seq analysis. The roles of sialic acid-binding, Ig-like lectin F (SiglecF)-positive neutrophils were further evaluated by adoptive transfer experiment and in vitro functional studies.

RESULTS

DEP exposure induced a unique population of lung granulocytes that coexpressed Ly6G and SiglecF. These cells differed phenotypically, morphologically, functionally, and transcriptionally from other SiglecF-expressing cells in the lungs. Our findings with murine models suggest that intratracheal challenge with DEPs induces the local release of adenosine triphosphate, which is a damage-associated molecular pattern signal. Adenosine triphosphate promotes the expression of SiglecF on neutrophils, and these SiglecF⁺ neutrophils worsen type 2 and 3 airway inflammation by producing high levels of cysteinyl leukotrienes and neutrophil extracellular traps. We also found Siglec8- (which corresponds to murine SiglecF) expressing neutrophils, and we found it in patients with asthma-chronic obstructive pulmonary disease overlap.

CONCLUSION

The SiglecF⁺ neutrophil is a novel and critical player in airway inflammation and targeting this population could reverse or ameliorate asthma.

Blood eosinophil cationic protein and eosinophil-derived neurotoxin are associated with different asthma expression and evolution in adults

BACKGROUND

Eosinophil-derived neurotoxin (EDN) and eosinophil cationic protein (ECP) are proteins released by activated eosinophils whose role in adult asthma remains unclear.

OBJECTIVE

To study associations between ECP, EDN and various asthma characteristics in adults from the Epidemiological Study on the Genetics and Environment of Asthma (EGEA).

METHODS

Plasma ECP and EDN levels were measured by ELISA. Cross-sectional analyses were performed in 941 adults (43±16 years old, 39% with asthma) at EGEA2 (2003-2007). Longitudinal analyses investigated the associations between EDN level at EGEA2 and changes in asthma characteristics between EGEA2 and EGEA3 (2011-2013, n=817). We used generalised estimated equations adjusted for age, sex, smoking status and body mass index to take into account familial dependence.

RESULTS

At EGEA2, both high ECP and EDN levels were associated with current asthma (adjusted OR (aOR) (95% CI): 1.69 (1.35-2.12) and 2.12 (1.76-2.57)). Among asthmatics, high EDN level was associated with asthma attacks (aOR: 1.50 (1.13-1.99)), wheezing and breathlessness (aOR: 1.38 (1.05-1.80)), use of asthma treatments (aOR: 1.91 (1.37-2.68)) and bronchial hyper-responsiveness (aOR: 2.03 (1.38-2.97)), even after further adjustment on ECP. High ECP level was associated with high neutrophil count and tended to be associated with chronic bronchitis. High EDN level at EGEA2 was associated with persistent asthma (aOR: 1.62 (1.04-2.52)), nocturnal symptoms (aOR from 2.19 to 3.57), worsening wheezing and breathlessness (aOR: 1.97 (1.36-2.85)) and nocturnal shortness of breath (aOR: 1.44 (1.04-1.98)) between EGEA2 and EGEA3.

CONCLUSIONS

EDN and ECP were associated with different asthma expression in adults. EDN could be a potential biomarker to monitor asthma evolution in adults.

Diagnostic possibility of the combination of exhaled nitric oxide and blood eosinophil count for eosinophilic asthma

BACKGROUND

Tests to identify reversible airflow limitation are important in asthma diagnosis, but they are time-consuming and it may be difficult for patients to cooperate. We aimed to evaluate whether the combination of fractional exhaled nitric oxide (FeNO) and blood eosinophil (B-Eos) can be used to distinguish some asthma patients who could avoid objective tests.

METHODS

We conducted a retrospective cohort study on 7463 suspected asthma cases between January 2014 and December 2019 in Chongqing, China, and identified 2349 patients with complete FeNO, B-Eos count, and spirometry data. Asthma was diagnosed by clinicians by the criteria of recurrent respiratory symptoms and a positive bronchial-provocation or bronchodilation test (BPT, BPD). We evaluated the diagnostic accuracy of FeNO or B-Eos alone or both in combination for asthma using receiver operating characteristic (ROC) curve analysis.

RESULTS

In this study, 824 patients were diagnosed with asthma. When FeNO and B-Eos counts were used in combination, the area under the ROC curve (AUC) for diagnosing asthma increased slightly (0.768 vs. 0.745 [FeNO] or 0.728 [B-Eos]; both P < 0.001). The odds ratio for having asthma increased progressively with a gradual increase in FeNO or B-Eos count (both P < 0.001; assessed using the Cochran-Armitage trend test). Further analysis of in-series combinations of different threshold values for these biomarkers indicated that moderately elevated biomarker levels (FeNO > 40 ppb and B-Eos > 300 cells/μl) support a diagnosis of asthma because diagnostic specificity was > 95% and the positive likelihood ratio (PLR) was > 10. This conclusion was verified when selecting the 2017-2019 data as the internal validation dataset.

CONCLUSION

FeNO or B-Eos count alone is insufficient to accurately diagnose asthma. Patients with moderately elevated biomarkers (FeNO > 40 ppb and B-Eos > 300 cells/μl) could be diagnosed with asthma and avoid objective tests when such tests are not feasible.

Associations of dermal diethyl phthalate level with changes in lung function test value mediated by absolute eosinophil count: A panel study of adults in southern Taiwan

Phthalate concentrations in indoor and outdoor dust are associated with respiratory disease. Both immunoglobulin E (IgE) and eosinophil count are associated with airway inflammation from exposure to environmental allergens. Dermal phthalate level can be used as a matrix for assessing personal exposure through direct absorption from the air, particle deposition, or contact with contaminated products. However, the association between dermal phthalate level and changes in lung function test values, as mediated by immunological response, remains unclear. In total, 237 adults in southern Taiwan were recruited. Spirometry measurements (in L) of forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were taken on visits 1 (2016-2018) and 2 (2019). Dermal phthalate level, absolute eosinophil count, and IgE level were recorded on visit 1. Mean changes in FVC and FEV1 decrease pear year, as determined through pairwise comparisons, were significant (^diffFVC_{per year}: -0.46, 95% CI: -0.51, -0.41; p < 0.001; ^diffFEV1_{per year}: -0.37, 95% confidence interval [CI]: -0.41, -0.34; p < 0.001). For FEV1 decrease, log-unit increases in dermal diethyl phthalate (DEP) were positively associated with ^diffFEV1_{per year} (β = 0.096; 95% CI: 0.042, 0.150; p = 0.001) and negatively associated with absolute eosinophil count (β= -0.201; 95% CI: -0.380, -0.023; p= 0.027). Log-unit increases in absolute eosinophil count were negatively associated with ^diffFEV1_{per year} (β= -0.109; 95% CI: -0.150, -0.068; p < 0.001). Absolute eosinophil count mediated 19.70% of the association between dermal DEP level and ^diffFEV1_{per year}. For FVC decrease, log-unit increases in dermal DEP were positively associated with ^diffFVC_{per year} (β = 0.095; 95% CI: 0.035, 0.155; p = 0.002) and negatively associated with absolute eosinophil count (β = -0.243; 95% CI: -0.427, -0.060; p = 0.010). Log-unit increases in absolute eosinophil count were negatively associated with ^diffFVC_{per year} (β= -0.122; 95% CI: -0.168, -0.076; p < 0.001). Absolute eosinophil count mediated 29.98% of the association between dermal DEP level and ^diffFVC_{per year}. The results suggest that dermal DEP level is positively associated with changes in lung function test values and is mediated by absolute eosinophil count.

Inflammatory patterns in fixed airflow obstruction are dependent on the presence of asthma

RATIONALE

Fixed airflow obstruction (FAO) can complicate asthma. Inflammation is a proposed underlying mechanism.

OBJECTIVE

Our aim in this cross-sectional investigation was to evaluate the blood leucocyte pattern and level of exhaled nitric oxide in asthmatics and non-asthmatics with or without FAO.

METHODS

A total of 11,579 individuals aged ≥20 years from the US National Health and Nutrition Examination Survey were included. They were grouped as: controls without asthma and FAO (n = 9,935), asthmatics without FAO (n = 674), asthmatics with FAO (n = 180) and non-asthmatics with FAO (n = 790). FAO was defined as post-bronchodilator FEV1/FVC < lower limit of normal. Exhaled nitric oxide ≥ 25ppb, blood eosinophil levels ≥300 cells/μL, and blood neutrophil levels ≥5100 cells/μL were defined as elevated. Stratified analyses for smoking and smoking history were performed.

RESULTS

Elevated blood eosinophil levels were more common in all groups compared to the controls, with the highest prevalence in the group with asthma and fixed airflow obstruction (p<0.01). In a multiple logistic regression model adjusted for potential confounders including smoking, the asthma groups had significantly higher odds ratios for elevated B-Eos levels compared to the control group (odds ratio 1.4, (confidence interval: 1.1-1.7) for the asthma group without fixed airflow obstruction and 2.5 (1.4-4.2) for the asthma group with fixed airflow obstruction). The group with fixed airflow obstruction without asthma had higher odds ratio for elevated blood neutrophil levels compared to the controls: 1.4 (1.1-1.8). Smoking and a history of smoking were associated to elevated B-Neu levels.

CONCLUSION

Fixed airflow obstruction in asthma was associated with elevated blood eosinophil levels, whereas fixed airflow obstruction without asthma was associated with elevated blood neutrophil levels.

Endotypes identified by cluster analysis in asthmatics and non-asthmatics and their clinical characteristics at follow-up: the case-control EGEA study

Background

Identifying relevant asthma endotypes may be the first step towards improving asthma management. We aimed identifying respiratory endotypes in adults using a cluster analysis and to compare their clinical characteristics at follow-up.

Methods

The analysis was performed separately among current asthmatics (CA, n=402) and never asthmatics (NA, n=666) from the first follow-up of the French EGEA study (EGEA2). Cluster analysis jointly considered 4 demographic, 22 clinical/functional (respiratory symptoms, asthma treatments, lung function) and four blood biological (allergy-related, inflammation-related and oxidative stress-related biomarkers) characteristics at EGEA2. The clinical characteristics at follow-up (EGEA3) were compared according to the endotype identified at EGEA2.

Results

We identified five respiratory endotypes, three among CA and two among NA: CA1 (n=53) with active treated adult-onset asthma, poor lung function, chronic cough and phlegm and dyspnoea, high body mass index, and high blood neutrophil count and fluorescent oxidation products level; CA2 (n=219) with mild asthma and rhinitis; CA3 (n=130) with inactive/mild untreated allergic childhood-onset asthma, high frequency of current smokers and low frequency of attacks of breathlessness at rest, and high IgE level; NA1 (n=489) asymptomatic, and NA2 (n=177) with respiratory symptoms, high blood neutrophil and eosinophil counts. CA1 had poor asthma control and high leptin level, CA2 had hyper-responsiveness and high interleukin (IL)-1Ra, IL-5, IL-7, IL-8, IL-10, IL-13 and TNF-α levels, and NA2 had high leptin and C reactive protein levels. Ten years later, asthmatics in CA1 had worse clinical characteristics whereas those in CA3 had better respiratory outcomes than CA2; NA in NA2 had more respiratory symptoms and higher rate of incident asthma than those in NA1.

Conclusion

These results highlight the interest to jointly consider clinical and biological characteristics in cluster analyses to identify endotypes among adults with or without asthma.

Genomics of asthma, allergy and chronic rhinosinusitis: novel concepts and relevance in airway mucosa

Genome wide association studies (GWASs) have revealed several airway disease-associated risk loci. Their role in the onset of asthma, allergic rhinitis (AR) or chronic rhinosinusitis (CRS), however, is not yet fully understood. The aim of this review is to evaluate the airway relevance of loci and genes identified in GWAS studies. GWASs were searched from databases, and a list of loci associating significantly (p < 10-8) with asthma, AR and CRS was created. This yielded a total of 267 significantly asthma/AR-associated loci from 31 GWASs. No significant CRS -associated loci were found in this search. A total of 170 protein coding genes were connected to these loci. Of these, 76/170 (44%) showed bronchial epithelial protein expression in stained microscopic figures of Human Protein Atlas (HPA), and 61/170 (36%) had a literature report of having airway epithelial function. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation analyses were performed, and 19 functional protein categories were found as significantly (p < 0.05) enriched among these genes. These were related to cytokine production, cell activation and adaptive immune response, and all were strongly connected in network analysis. We also identified 15 protein pathways that were significantly (p < 0.05) enriched in these genes, related to T-helper cell differentiation, virus infection, JAK-STAT signaling pathway, and asthma. A third of GWAS-level risk loci genes of asthma or AR seemed to have airway epithelial functions according to our database and literature searches. In addition, many of the risk loci genes were immunity related. Some risk loci genes also related to metabolism, neuro-musculoskeletal or other functions. Functions overlapped and formed a strong network in our pathway analyses and are worth future studies of biomarker and therapeutics.

Targeting neutrophils in asthma: A therapeutic opportunity?

Suppression of airway inflammation with inhaled corticosteroids has been the key therapeutic approach for asthma for many years. Identification of inflammatory phenotypes in asthma has moreover led to important breakthroughs, e.g. with specific targeting of the IL-5 pathway as add-on treatment in difficult-to-treat eosinophilic asthma. However, the impact of interfering with the neutrophilic component in asthma is less documented and understood. This review provides an overview of established and recent insights with regard to the role of neutrophils in asthma, focusing on research in humans. We will describe the main drivers of neutrophilic responses in asthma, the heterogeneity in neutrophils and how they could contribute to asthma pathogenesis. Moreover we will describe findings from clinical trials, in which neutrophilic inflammation was targeted. It is clear that neutrophils are important actors in asthma development and play a role in exacerbations. However, more research is required to fully understand how modulation of neutrophil activity could lead to a significant benefit in asthma patients with airway neutrophilia.

Blood eosinophil level and lung function trajectories: cross-sectional and longitudinal studies in European cohorts

Background

Elevated blood eosinophils have been associated with lower lung function and are believed to be associated with accelerated lung function decline.

Method

Blood eosinophils were measured in four cohorts: <45 years cohort within the Vlagtwedde–Vlaardingen (V&V) study, the Uppsala cohort of the European Community Respiratory Health Survey (ECRHS-Uppsala; <45 years), ≥45 years cohort within the V&V study, and the Rotterdam study (≥45 years). Blood eosinophils at baseline were classified as normal (<300 cells·μL⁻¹) or elevated (≥300 cells·μL⁻¹). Lung function was measured at baseline and follow-up with spirometry: forced expiratory volume in 1 s (FEV₁), vital capacity (VC) and their ratio FEV₁/VC. The association between blood eosinophils and lung function was tested cross-sectionally using linear regression and longitudinally using a mixed model, both adjusted for age, sex, height, pack-years smoking and smoking status. Stratified analyses were done for asthma.

Results

Elevated blood eosinophils were associated with lower FEV₁ (regression coefficient −147 mL (95% CI −188 to −105 mL)), VC (−120 mL (−165 to −75 mL)) and FEV₁/VC (−1.3% (−1.9% to −0.6%)) at baseline in the two <45 years cohorts, and with lower FEV₁ (−70 mL (−112 to −27 mL)) and FEV₁/VC (−1.8% (−2.6% to −1.0%)) in the two ≥45 years cohorts. Elevated blood eosinophils were associated with an accelerated decline in FEV₁ (−5.5 mL·year⁻¹ (95% CI −10.5 to −0.5 mL·year⁻¹)) and VC (−6.4 mL·year⁻¹ (−11.26 to −1.5 mL·year⁻¹)) compared to normal blood eosinophils in the younger asthmatic subjects in the longitudinal studies.

Conclusion

Elevated blood eosinophils are associated with lower lung function in the general population and with an accelerated lung function decline among asthmatic individuals.

Elevated blood eosinophils (≥300 cells per μL) associate with lower lung function in an adult general population and with a worse lung function trajectory in adult asthmatic individualshttps://bit.ly/3fJJ10h

Blood Eosinophil Count as a Predictor of Lung Function Decline in Healthy Individuals

BACKGROUND

Little is known about the effect of blood eosinophil count (BEC) on a decline in lung function in healthy individuals.

OBJECTIVE

Using a well-established health screening database, we assessed the associations between BEC and a decline in lung function, measured as the forced expiratory volume in 1 second (FEV₁).

METHODS

Serial BEC and FEV₁ data were analyzed using linear mixed models adjusted for gender, height, and smoking status. The association between BEC consistency and a decline in FEV₁ was evaluated in subpopulation analyses.

RESULTS

A total of 4634 individuals were enrolled. The mean number of health screenings was 7.49 over an average of 11.74 years of observation. A higher log2-transformed BEC was significantly associated with a greater decline in FEV₁ that was stronger in nonsmokers (P = 8.56 × 10^-8) than in smokers (P = 1.52 × 10^-3). In subpopulation analyses of 2018 individuals with consistent BECs, those with BECs consistently ≥100/μL (P = 4.58 × 10^-6), ≥200/μL (P = 3.53 × 10^-7), and ≥300/μL (P = 1.12 × 10^-3) had a significantly higher dose-dependent FEV₁ decline than those with BECs consistently <100/μL. A BEC threshold of 100/μL in nonsmokers and 200/μL in smokers may predict an accelerated decline in FEV₁.

CONCLUSIONS

BEC is associated with a decline in FEV₁, and a consistently high BEC is an independent risk factor for an accelerated decline in FEV₁. These results suggest the use of the BEC to identify healthy individuals at high risk for developing chronic lung disease, which in turn may enable a tailored preventive strategy.

Clinical characteristics and biomarkers analysis of asthma inflammatory phenotypes

Aim: Asthma inflammatory phenotypes facilitate treatment, their clinical characteristics and biomarkers were analyzed. Materials & methods: A total of 176 asthmatics were divided into eosinophilic asthma (EA), neutrophilic asthma (NA), paucigranulocytic asthma and mixed-granulocytic asthma by induced sputum. Results: EA, NA and paucigranulocytic asthma patients were 65 (36.9%), 31 (17.6%) and 75 (42.6%). Sputum IL-5 and IL-13, blood IL-13, fractional exhaled nitric oxide (FeNO) were related to EA, the areas under the receiver operating characteristic curve were 0.790, 0.846, 0.828, 0.830, combined FeNO with blood IL-13 was 0.872. Sputum and blood IL-8, blood IL-17 were related to NA, their area under the receiver operating characteristic curve was 0.939, 0.844, 0.821, combined blood IL-8 with IL-17 was 0.882. Conclusion: Blood IL-13 and FeNO, blood IL-8 and IL-17 were alternative biomarkers of EA and NA, respectively.

Evolving phenotypes to endotypes: is precision medicine achievable in asthma?

Introduction: The development of biologic molecules led to a drastic change in the therapeutic approach to asthma. With the prospect of acting on different pathophysiological mechanisms of the disease, the idea of precision medicine was developed, in which a single molecule is able to modify a specific triggering mechanism. Thus, it seemed limiting to stop at the distinction of patients phenotypes and the concept of endotypes became more relevant in the therapeutic approach.Areas covered: This review deepened the topic of precision medicine through the transition from phenotyping to endotyping. We performed a review of the literature, preferring articles quoted in Medline and published in journals with an impact factor. Results showed that it is fundamental to take into consideration the role of biomarkers and the related therapies currently available for precision medicine.Expert opinion: The possible overlap of patients in different phenotypes requires a more precise classification, which considers endotypization. With the development of biological drugs able to modify and modulate some pathophysiological mechanisms of the disease, the theoretical concept of endotyping becomes practical, allowing the clinician to choose the specific mechanism to 'attack' in order to control the disease.

The peripheral blood inflammatory patterns in the control levels of asthma in children

OBJECTIVE

Asthma is the most common chronic inflammatory disease of childhood, but there are no useful and easily accessible laboratory tests routinely used in the diagnosis and follow-up of this disease in children. Therefore, this study aimed to investigate the roles of white blood cell (WBC) count, platelet count, mean platelet volume (MPV), and eosinophil percentage as full blood count inflammatory markers in evaluating the control level and follow-up of asthma in the pediatric age group.

METHODS

A retrospective review of patient records and files of 3,580 patients diagnosed with asthma at the University of Health Sciences in Ankara, Turkey was performed. Patients who met inclusion/exclusion criteria were divided into two groups based on the asthma control level: controlled and uncontrolled. Laboratory data were compared according to the asthma control levels, drug use status, and atopy status of the patients.

RESULTS

A total of 348 patients between 4 and 18 years of age, who were followed-up with the diagnosis of asthma, were included in this study. A significant difference was found between the controlled and uncontrolled groups of asthma patients in terms of the eosinophil percentage (mean ± SD, respectively; 3.493 ± 2.24; 4.992 ± 3.43; p = .003). When patients were grouped according to their asthma control levels and atopy status, only the eosinophil percentages were different in the logistic regression analysis (odds ratio = 1.276, 95% confidence interval = 1.113-1.462).

CONCLUSION

Our study showed that the percentage of eosinophils can be used as an asthma control parameter, but additional prospective studies would be desirable to confirm our results.

Discriminatory Molecular Biomarkers of Allergic and Nonallergic Asthma and Its Severity

Asthma is a complex disease comprising various phenotypes and endotypes, all of which still need solid biomarkers for accurate classification. In a previous study, we defined specific genes related to asthma and respiratory allergy by studying the expression of 94 genes in a population composed of 4 groups of subjects: healthy control, nonallergic asthmatic, asthmatic allergic, and nonasthmatic allergic patients. An analysis of differential gene expression between controls and patients revealed a set of statistically relevant genes mainly associated with disease severity, i.e., CHI3L1, IL-8, IL-10, MSR1, PHLDA1, PI3, and SERPINB2. Here, we analyzed whether these genes and their proteins could be potential asthma biomarkers to distinguish between nonallergic asthmatic and asthmatic allergic subjects. Protein quantification was determined by ELISA (in serum) or Western blot (in protein extracted from peripheral blood mononuclear cells or PBMCs). Statistical analyses were performed by unpaired t-test using the Graph-Pad program. The sensitivity and specificity of the gene and protein expression of several candidate biomarkers in differentiating the two groups (and the severity subgroups) was performed by receiver operating characteristic (ROC) curve analysis using the R program. The ROC curve analysis determined single genes with good sensitivity and specificity for discriminating some of the phenotypes. However, interesting combinations of two or three protein biomarkers were found to distinguish the asthma disease and disease severity between the different phenotypes of this pathology using reproducible techniques in easy-to-obtain samples. Gene and protein panels formed by single biomarkers and biomarker combinations have been defined in easily obtainable samples and by standardized techniques. These panels could be useful for characterizing phenotypes of asthma, specifically when differentiating asthma severity.

Increase in blood eosinophils during follow-up is associated with lung function decline in adult asthma

BACKGROUND

Asthma is associated with accelerated rate of lung function (FEV₁) decline.

OBJECTIVE

To determine predictive factors associated with FEV₁ decline in adult asthma.

METHODS

A retrospective study was conducted in 229 asthmatics recruited from the University Asthma Clinic of Liege. Subjects had at least two visits with post-bronchodilation (post-BD) FEV₁ and minimum one year between them. A multivariable linear regression analysis was conducted in order to come up with factors associated with lung function decline.

RESULTS

Post-BD FEV₁ decline in % predicted. y^-1 was 0.2 (95%CI -2.0 to 2.8) in the overall population. Our population was made up of mild to moderate asthmatics [1] for 58%, aged 50 (41-60) years old, 62% were female and 59% were atopic. Median ICS dose was 1000 μg beclomethasone equivalent (CFC)/day with 81% treated at baseline. Time between visits was 46.8 ± 32.1 months. The univariate linear regression analysis revealed a negative association between % predicted FEV₁ decline and baseline ACQ (p < 0.0001) and blood eosinophils (% and/mm³) (p < 0.0001 and p < 0.0001). A positive association was found between % predicted FEV₁ decline and baseline pre-BD FEV1 (mL) values (p = 0.001), blood neutrophils (%) (p = 0.02), change in blood eosinophils (%) (p < 0.0001), time between visits (months) (p < 0.0001). The predictive variables for accelerated decline highlighted by the multivariable analysis (r² = 0.39) were change in blood eosinophils (%) over time (p = 0.002) and time between visits (months) (p < 0.0001).

CONCLUSION

These findings highlight a new value for blood eosinophil counts as their increase over time predicts greater lung function decline in asthma.

Newborn DNA-methylation, childhood lung function, and the risks of asthma and COPD across the life course

RATIONALE

We aimed to identify differentially methylated regions (DMRs) in cord blood DNA associated with childhood lung function, asthma and chronic obstructive pulmonary disease (COPD) across the life course.

METHODS

We meta-analysed epigenome-wide data of 1688 children from five cohorts to identify cord blood DMRs and their annotated genes, in relation to forced expiratory volume in 1 s (FEV₁), FEV₁/forced vital capacity (FVC) ratio and forced expiratory flow at 75% of FVC at ages 7-13 years. Identified DMRs were explored for associations with childhood asthma, adult lung function and COPD, gene expression and involvement in biological processes.

RESULTS

We identified 59 DMRs associated with childhood lung function, of which 18 were associated with childhood asthma and nine with COPD in adulthood. Genes annotated to the top 10 identified DMRs were HOXA5, PAOX, LINC00602, ABCA7, PER3, CLCA1, VENTX, NUDT12, PTPRN2 and TCL1A. Differential gene expression in blood was observed for 32 DMRs in childhood and 18 in adulthood. Genes related with 16 identified DMRs were associated with respiratory developmental or pathogenic pathways.

INTERPRETATION

Our findings suggest that the epigenetic status of the newborn affects respiratory health and disease across the life course.

Eosinophil levels predict lung function deterioration in apparently healthy individuals

Background

While chronic respiratory diseases are among the leading causes of mortality and morbidity worldwide, little is known about the effect of blood eosinophil levels on lung function trajectories among healthy individuals.

Methods

We analyzed data of apparently healthy individuals (n=18,089) recruited for the Tel Aviv Medical Center Inflammation Survey. Blood eosinophil levels were compared between participants with normal and those with abnormal lung function. Multivariate regression was used to assess the OR of forced expiratory volume in 1 second (FEV₁) deterioration according to baseline eosinophils in subjects with normal lung function (n=4,141) during a follow-up period of 4 years.

Results

Participants with an abnormal, as opposed to a normal, pulmonary function test (PFT) (n=1,832, 10.1%) had significantly higher eosinophil levels, expressed as a percentage or count (2.99%±2.00% compared to 2.67%±1.88% and 0.2210e3/µL±0.163/µL compared to 0.1810e3/µL±0.183/µL, respectively; P<0.001 for both). Among participants with a normal PFT at baseline, those with an eosinophil percentage higher than 4% showed a higher risk for FEV₁ decline above 60 mL/year (OR=1.199, 95% CI=1.005-1.431, P=0.044).

Conclusion

Our study suggests that higher blood eosinophil levels can predict PFT deterioration even in apparently healthy subjects, implying that these individuals could benefit from frequent lung function evaluation.

Biomarkers in asthma: state of the art

Asthma is a heterogenous disease characterized by multiple phenotypes driven by different mechanisms. The implementation of precision medicine in the management of asthma requires the identification of phenotype-specific markers measurable in biological fluids. To become useful, these biomarkers need to be quantifiable by reliable systems, reproducible in the clinical setting, easy to obtain and cost-effective. Using biomarkers to predict asthma outcomes and therapeutic response to targeted therapies has a great clinical significance, particularly in severe asthma. In the last years, significant research has been realized in the identification of valid biomarkers for asthma. This review focuses on the existent and emerging biomarkers with clinical higher applicability in the management of asthma.

Recent developments and highlights in biomarkers in allergic diseases and asthma

The potential of precision medicine in allergy and asthma has only started to be explored. A significant clarification in the pathophysiology of rhinitis, chronic rhinosinusitis, asthma, food allergy and drug hypersensitivity was made in the last decade. This improved understanding led to a better classification of the distinct phenotypes and to the discovery of new drugs such as biologicals, targeting phenotype-specific mechanisms. Nevertheless, many conditions remain poorly understood such as non-eosinophilic airway diseases or non-IgE-mediated food allergy. Moreover, there is a need to predict the response to specific therapies and the outcome of drug and food provocations. The identification of patients at risk of progression towards severity is also an unmet need in order to establish adequate preventive or therapeutic measures. The implementation of precision medicine in the clinical practice requires the identification of phenotype-specific markers measurable in biological matrices. To become useful, these biomarkers need to be quantifiable by reliable systems, and in samples obtained in an easy, rapid and cost-efficient way. In the last years, significant research resources have been put in the identification of valid biomarkers for asthma and allergic diseases. This review summarizes these recent advances with focus on the biomarkers with higher clinical applicability.

Serum sST2 levels predict severe exacerbation of asthma

BACKGROUND

Neutrophilic inflammation is associated with poorly controlled asthma. Serum levels of sST2, a soluble IL-33 receptor, increase in neutrophilic lung diseases. We hypothesized that high serum sST2 levels in stable asthmatics are a predictor for exacerbation within a short duration.

METHODS

This prospective observational study evaluated the serum sST2 levels of 104 asthmatic patients who were treated by a lung disease specialist with follow-ups for 3 months.

RESULTS

High serum sST2 levels (> 18 ng/ml) predicted severe asthma exacerbation within 3 months. Serum sST2 levels correlated positively with asthma severity (treatment step), airway H2O2 levels, and serum IL-8 levels. High serum sST2 levels and blood neutrophilia (> 6000 /μl) were independent predictors of exacerbation. We defined a post-hoc exacerbation-risk score combining high serum sST2 level and blood neutrophilia, which stratified patients into four groups. The score predicted exacerbation-risk with an area under curve of 0.91 in the receiver operating characteristic curve analysis. Patients with the highest scores had the most severe phenotype, with 85.7% showing exacerbation, airflow limitation, and corticosteroid-insensitivity.

CONCLUSIONS

High serum sST2 levels predicted exacerbation within the general asthmatic population and, when combined with blood neutrophil levels, provided an exacerbation-risk score that was an accurate predictor of exacerbation occurring within 3 months.

Sex-Specific Asthma Phenotypes, Inflammatory Patterns, and Asthma Control in a Cluster Analysis

BACKGROUND

Asthma is a heterogeneous disease with complex mechanisms and involves many risk factors and in vivo cellular molecules. It is notable that sex differences may have a potential effect on asthma phenotype.

OBJECTIVE

To identify sex-specific phenotypes and health outcomes of asthma.

METHODS

We conducted the Taiwanese Adult Asthma Cohorts study to enroll female (n = 421) and male (n = 299) adult patients with stable asthma. Eight variables were selected by a factor analysis. We further performed a 2-step sensitivity cluster analysis to classify asthma clusters. The risks of asthma-related outcomes among the clusters were assessed using simple logistic regressions.

RESULTS

Three different clusters were identified in males and females. In the female clusters, atopy/eosinophil-predominant (cluster 2), and obesity/neutrophil-predominant pattern (cluster 3) had more than a 2-fold risk of asthma exacerbations (odds ratio, 2.51; 95% CI, 1.12-5.59 and odds ratio, 2.22; 95% CI, 1.01-4.93). In the male clusters, current smoker/neutrophilic atopic cluster (cluster 5) and ex-smoker/eosinophil-predominant or mixed inflammatory pattern (cluster 6) also had a higher risk of asthma exacerbations.

CONCLUSIONS

This study identified heterogeneous characteristics between sexes. In females, the analysis showed atopy with eosinophil-predominant and obese with neutrophil-predominant inflammation. Two distinct asthma phenotypes were found in current and ex-smokers in males. Understanding asthma phenotypes and explaining the potentially biological pathways have become important.

Prevalence, characteristics and management of frequently exacerbating asthma patients: an observational study in Sweden (PACEHR)

The aim of the study was to investigate the prevalence, management and characteristics of asthma patients with frequent exacerbations.Data from asthma patients (aged ≥18 years) identified in primary care medical records were linked to Swedish national health registries. Exacerbations were defined as hospitalisations, emergency visits and/or collection of oral steroids. Frequent exacerbations were defined as two or more exacerbations per year during the 3-year observation period.Of 18 724 asthma patients, 81.49% had no exacerbations and 6.3% had frequent exacerbations in the year prior to the index date. Frequent exacerbations were observed yearly for 1.8% of the patients. Frequent exacerbators were older, more often females, and had increased eosinophil and neutrophil counts, lower lung function, and more comorbidities than patients without exacerbations. There was a slight increase in asthma medication claims and a slight decrease in physician visits compared with baseline, both in the group with and the group without frequent exacerbations.Patients with frequent exacerbations were characterised by greater age, female predominance, high eosinophil and neutrophil counts, and high prevalence of comorbidities. This study indicates that the Swedish healthcare system lacks efficiency to adjust treatment and management for this patient group. With new treatment options targeting severe asthma available, identification of these patients should be in focus to ensure reduction of exacerbations.

Associations between blood eosinophils and decline in lung function among adults with and without asthma

Eosinophilic inflammation and airway remodelling are characteristic features of asthma, but the association between them is unclear. We assessed associations between blood eosinophils and lung function decline in a population-based cohort of young adults.We used linear mixed models to analyse associations between blood eosinophils and spirometry at 21, 26, 32 and 38 years adjusting for sex, smoking, asthma and spirometry at age 18 years. We further analysed associations between mean eosinophil counts and changes in spirometry from ages 21 to 38 years.Higher eosinophils were associated with lower forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) ratios and lower FEV₁ % predicted values for both pre- and post-bronchodilator spirometry (all p-values ≤0.048). Although eosinophil counts were higher in participants with asthma, the associations between eosinophils and spirometry were similar among participants without asthma or wheeze. Participants with mean eosinophil counts >0.4×10⁹ cells·L^-1 between 21 and 38 years had greater declines in FEV₁/FVC ratios (difference 1.8%, 95% CI 0.7-2.9%; p=0.001) and FEV₁ values (difference 3.4% pred, 95% CI 1.5-5.4% pred); p=0.001) than those with lower counts.Blood eosinophils are associated with airflow obstruction and enhanced decline in lung function, independently of asthma and smoking. Eosinophilia is a risk factor for airflow obstruction even in those without symptoms.

Oxidative stress biomarkers and asthma characteristics in adults of the EGEA study

Asthma is an oxidative stress related disease, but associations with asthma outcomes are poorly studied in adults. We aimed to study the associations between several biomarkers related to oxidative stress and various asthma outcomes.Cross-sectional analyses were conducted in 1388 adults (mean age 43 years, 44% with asthma) from the Epidemiological Study of the Genetics and Environment of Asthma (EGEA2). Three blood antioxidant enzyme activities (biomarkers of response to oxidative stress) and exhaled breath condensate 8-isoprostanes and plasma fluorescent oxidation products (FlOPs) levels (two biomarkers of damage) were measured. Associations between biomarkers and 1) ever asthma and 2) asthma attacks, asthma control and lung function in participants with asthma were evaluated using regression models adjusted for age, sex and smoking.Biomarkers of response were unrelated to asthma outcomes. Higher 8-isoprostane levels were significantly associated with ever asthma (odds ratio for one interquartile range increase 1.28 (95% CI 1.06-1.67). Among participants with asthma, 8-isoprostane levels were negatively associated with adult-onset asthma (0.63, 0.41-0.97) and FlOPs levels were positively associated with asthma attacks (1.33, 1.07-1.65), poor asthma control (1.30, 1.02-1.66) and poor lung function (1.34, 1.04-1.74).Our results suggest that 8-isoprostanes are involved in childhood-onset asthma and FlOPs are linked to asthma expression.

Clinical and biological characteristics of the French COBRA cohort of adult subjects with asthma

The COhort of BRonchial obstruction and Asthma (COBRA) is a longitudinal cohort that involves 12 French academic institutions. DNA, serum samples and clinical data are collected at entry and every 6 months thereafter.Of 1080 patients with asthma recruited between 2007 and 2015, 401 had mild/moderate and 613 had severe asthma. In cross-sectional analyses, compared with patients with milder disease, patients with severe asthma had more symptoms, exacerbations, hospitalisations and visits to the emergency department during the preceding 12 months, higher numbers of blood eosinophils, and more comorbidities. More than 60% of patients with severe asthma were therapy-uncontrolled at entry, and 152 of them were being treated with omalizumab. In addition, patients with asthma who had the highest eosinophilia levels (>300/mm³) had shorter asthma duration, lower lung function, and higher rates of severe exacerbations and unacceptable asthma control than patients with lower eosinophil counts.Longitudinal analyses performed in 427 patients with asthma with at least three differential blood cell counts demonstrated that both eosinophil numbers and eosinophil increase over time were associated with the number of exacerbations occurring until the next visit and with Juniper score.Studies with the COBRA cohort will help to improve knowledge concerning the risk and biological factors associated with asthma severity and to better understand their influence on the disease trajectory.