Altered Innate Immune Responses in Neutrophils from Patients with Well- and Suboptimally Controlled Asthma

Functional immunophenotyping of blood neutrophils identifies novel endotypes of viral response in preschool children with recurrent wheezing

BACKGROUND

Preschool children with recurrent wheezing are heterogeneous, with differing responses to respiratory viral infections. Although neutrophils are crucial for host defense, their function has not been studied in this population.

OBJECTIVE

We performed functional immunophenotyping on isolated blood neutrophils from 52 preschool children with recurrent wheezing (aeroallergen sensitization, n = 16; no sensitization, n = 36).

METHODS

Blood neutrophils were purified and cultured overnight with polyinosinic:polycytidylic acid [poly(I:C)] as a viral analog stimulus. Neutrophils underwent next-generation sequencing with Reactome pathway analysis and were analyzed for cytokine secretion, apoptosis, myeloperoxidase, and extracellular DNA release. CD14+ monocytes were also exposed to neutrophil culture supernatant and analyzed for markers of M1 and M2 activation.

RESULTS

A total of 495 genes, related largely to the innate immune system and neutrophil degranulation, were differently expressed in children with versus without aeroallergen sensitization. Functional experiments identified more neutrophil degranulation and extracellular trap formation (ie, more myeloperoxidase and extracellular DNA) and less neutrophil proinflammatory cytokine secretion in children with aeroallergen sensitization. Neutrophils also shifted CD14+ monocytes to a more anti-inflammatory (ie, M2) phenotype in sensitized children and a more proinflammatory (ie, M1) phenotype in nonsensitized children. Although both groups experienced viral exacerbations, annualized exacerbation rates prompting unscheduled health care were also higher in children without aeroallergen sensitization after enrollment.

CONCLUSIONS

Systemic neutrophil responses to viral infection differ by allergic phenotype and may be less effective in preschool children without allergic inflammation. Further studies of neutrophil function are needed in this population, which often has less favorable therapeutic responses to inhaled corticosteroids and other therapies directed at type 2-high inflammation.

Novel Therapies for Pneumonia-Associated Severe Asthma Phenotypes

Distinct asthma phenotypes are emerging from well-defined cohort studies and appear to be associated with a history of pneumonia. Asthmatics are more susceptible to infections caused by Streptococcus pneumoniae; however, the mechanisms that underlie defective immunity to this pathogen are still being elucidated. Here, we discuss how alternatively activated macrophages (AAMs) in asthmatics are defective in bacterial phagocytosis and how respiratory viruses disrupt essential host immunity to cause bacterial dispersion deeper into the lungs. We also describe how respiratory pathogens instigate neutrophilic inflammation and amplify type-2 inflammation in asthmatics. Finally, we propose novel dual-acting strategies including granulocyte-colony-stimulating factor receptor (G-CSFR) antagonism and specialised pro-resolving mediators (SPMs) to suppress type-2 and neutrophilic inflammation without compromising pathogen clearance.

The Correlation Between Asthma Severity and Neutrophil to Lymphocyte Ratio

Background—The prognosis is essential in management and follows up of asthmatic patients. Neutrophil to lymphocyte ratio is considered as the common prognostic marker for many diseases especially the asthma. Aim of study—To assess the relationship between asthma severity and neutrophil to lymphocyte ratio in comparison to healthy controls. Patients and methods—This study is a cross sectional study conducted in Respiratory Consultancy Clinic in Baghdad Teaching Hospital in Medical City during the period from 1st of October, 2018 to 31st of March, 2019 on sample of 50 asthmatic patients and 50 healthy controls. The diagnosis of asthma was confirmed by the supervisor through clinical symptoms, signs, spirometery with reversibility test (according to GINA guideline.). Results—A highly significant difference was observed between asthmatic cases and controls regarding age (p<0.001). A significant association was observed between obesity and asthmatic cases (p=0.001). There was a highly significant association between high neutrophil/lymphocyte ratio and asthmatic cases (p<0.001). The neutrophil/lymphocyte ratio was significantly increased with advanced age, females, severe and uncontrolled asthma. Conclusions—The neutrophil to lymphocyte ratio is useful biomarker in assessment of asthma severity.

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.

Accelerated reactivity of blood granulocytes in patients with atopic bronchial asthma out of exacerbation

Reactive oxygen species (ROS) are important in bronchial asthma (BA) pathogenesis owing to accumulation of activated granulocytes in the lungs. But the ROS-producing activity of the cells is insufficiently understood in the blood of BA patients. This study analyzes the kinetics of phagocyte respiratory burst in the blood to improve the methods of BA patients monitoring. Patients with atopic BA out of exacerbation (n=60) and healthy controls (n=43) were recruited. The time-course of respiratory response to opsonized zymosan (OZ) was recorded in the whole blood using luminol-dependent chemiluminescence (CL), and its activation kinetics (lag-time, rate, amplitude, ROS production) was calculated. The discriminative power of ROS generation kinetics was defined by Receiver Operating Characteristic (ROC) curve analysis. Standard physiological respiratory parameters of patients did not differ from the controls. More rapid response to OZ was recorded in BA patient samples versus the controls. The primed state of phagocytes in the blood of BA patients was corroborated by significant weakening formyl peptide priming effect. The adhesion of granulocytes to cultured human endothelial cells was two-fold higher in BA patients versus controls. ROC curve analysis exhibited good discriminative effectiveness of the CL kinetics to compare BA individuals with the controls. The highest power (86% sensitivity and 90% specificity) was achieved at a linear combination of the parameters. We assume that the assessment of phagocyte reactivity based on the analysis of the response kinetic profile is a good test for monitoring of the state in BA patients.

Advanced Role of Neutrophils in Common Respiratory Diseases

Respiratory diseases, always being a threat towards the health of people all over the world, are most tightly associated with immune system. Neutrophils serve as an important component of immune defense barrier linking innate and adaptive immunity. They participate in the clearance of exogenous pathogens and endogenous cell debris and play an essential role in the pathogenesis of many respiratory diseases. However, the pathological mechanism of neutrophils remains complex and obscure. The traditional roles of neutrophils in severe asthma, chronic obstructive pulmonary diseases (COPD), pneumonia, lung cancer, pulmonary fibrosis, bronchitis, and bronchiolitis had already been reviewed. With the development of scientific research, the involvement of neutrophils in respiratory diseases is being brought to light with emerging data on neutrophil subsets, trafficking, and cell death mechanism (e.g., NETosis, apoptosis) in diseases. We reviewed all these recent studies here to provide you with the latest advances about the role of neutrophils in respiratory diseases.

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

To what extent blood granulocyte patterns may predict asthma control remains under-studied. Our aim was to study associations between blood neutrophilia and eosinophilia and asthma control outcomes in adults.Analyses were conducted in 474 asthmatics from the first follow-up of the Epidemiological Study on the Genetics and Environment of Asthma (EGEA2), including 242 asthmatics who were adults a decade earlier (EGEA1). At EGEA2, asthma control was assessed using the Global Initiative for Asthma definition (2015), and asthma exacerbations by use of urgent care or courses of oral corticosteroids in the past year. Blood EOS^lo/EOS^hi was defined as </≥250 eosinophils·mm^-3, respectively, and NEU^lo/NEU^hi as </≥5000 neutrophils·mm^-3, respectively. Estimates were adjusted for age, sex and smoking.At EGEA2, NEU^hi was associated with asthma exacerbations and poor asthma control (OR >2.10). EOS^hi was associated with higher bronchial hyperresponsiveness (BHR) (OR (95% CI) 2.21 (1.24-3.97)), poor lung function (p=0.02) and higher total IgE level (p=0.002). Almost 50% of asthmatics had a persistent pattern between surveys. Persistent NEU^hi was associated with poor asthma control at EGEA2 (OR (95% CI) 3.09 (1.18-7.05)). EOS^hi at EGEA1 and persistent EOS^hi were associated with higher BHR (OR (95% CI) 2.36 (1.10-5.07) and 3.85 (1.11-13.34), respectively), poor lung function (p<0.06) and higher immunoglobulin E level (p<10^-4) at EGEA2.Granulocyte patterns were differently associated with asthma outcomes, suggesting specific roles for each one, which could be tested as predictive signatures.