Exacerbation-Prone Asthma: A Separate Bioclinical Phenotype?

Socioeconomic status, diet, and recurrent severe asthma exacerbations in Puerto Rican youth

Background

Why Puerto Rican youths have higher rates of severe asthma exacerbations (SAEs) than their non-Hispanic White peers is unclear.

Objective

We aimed to identify risk factors associated with recurrent SAEs in Puerto Rican youths with asthma.

Methods

We performed cross-sectional and longitudinal analyses of recurrent SAEs in 209 Puerto Rican youths with asthma who participated in 2 cross-sectional studies approximately 5.2 years apart: the Puerto Rico Genetics of Asthma and Lifestyle study (visit 1, participants aged 6-14 years) and the Epigenetic Variation and Childhood Asthma in Puerto Ricans study (visit 2, participants aged 9-20 years). Recurrent SAEs were defined as at least 2 SAEs in the previous year.

Results

Of the youths in our study, there were 80 (38.3%) and 47 (22.4%) with recurrent SAEs at visit 1 and visit 2, respectively, and 31 participants (14.8%) had persistent recurrent SAEs (ie, recurrent SAEs at both visits). In multivariable analyses, low household income was significantly associated with 2.4 to 12.3 times increased odds of recurrent SAEs in all analyses, with stronger longitudinal associations. Low parental education level, nonprivate or employer-based health insurance, overweight or obesity, residential proximity to a major road, and low or moderate level of outdoor activity were each significantly associated with recurrent SAEs in at least 1 analysis. Further, persistence of low parental numeracy level, low household income, and an unhealthy diet were each associated with persistent recurrent SAEs.

Conclusion

In this study of Puerto Rican youths with asthma, persistence of low parental numeracy level, a low household income, and an unhealthy diet were associated with persistent recurrent SAEs. Our findings support policies promoting equity and healthy lifestyles for Puerto Rican children and their families.

Exacerbation-prone pediatric asthma is associated with arginine, lysine, and methionine pathway alterations

BACKGROUND

The asthma of some children remains poorly controlled, with recurrent exacerbations despite treatment with inhaled corticosteroids. Aside from prior exacerbations, there are currently no reliable predictors of exacerbation-prone asthma in these children and only a limited understanding of the potential underlying mechanisms.

OBJECTIVE

We sought to quantify small molecules in the plasma of children with exacerbation-prone asthma through mass spectrometry-based metabolomics. We hypothesized that the plasma metabolome of these children would differ from that of children with non-exacerbation-prone asthma.

METHODS

Plasma metabolites were extracted from 4 pediatric asthma cohorts (215 total subjects, with 41 having exacerbation-prone asthma) and detected with a mass spectrometer. High-confidence annotations were retained for univariate analysis and were confirmed by a sensitivity analysis in subjects receiving high-dose inhaled corticosteroids. Metabolites that varied by cohort were excluded. MetaboAnalyst software was used to identify pathways of interest. Concentrations were calculated by reference standardization.

RESULTS

We identified 32 unique, cohort-independent metabolites that differed in children with exacerbation-prone asthma compared to children with non-exacerbation-prone asthma. Comparison of metabolite concentrations to literature-reported values for healthy children revealed that most metabolites were decreased in both asthma groups, but more so in exacerbation-prone asthma. Pathway analysis identified arginine, lysine, and methionine pathways as most impacted.

CONCLUSIONS

Several plasma metabolites are perturbed in children with exacerbation-prone asthma and are largely related to arginine, lysine, and methionine pathways. While validation is needed, plasma metabolites may be potential biomarkers for exacerbation-prone asthma in children.

Functional immunophenotyping of children with critical status asthmaticus identifies differential gene expression responses in neutrophils exposed to a poly(I:C) stimulus

The host immune response to a viral immune stimulus has not been examined in children during a life-threatening asthma attack. We determined whether we could identify clusters of children with critical asthma by functional immunophenotyping using an intracellular viral analog stimulus. We performed a single-center, prospective, observational cohort study of 43 children ages 6-17 years admitted to a pediatric intensive care unit for an asthma attack between July 2019 to February 2021. Neutrophils were isolated from children, stimulated overnight with LyoVec poly(I:C), and mRNA was analyzed using a targeted Nanostring immunology array. Network analysis of the differentially expressed transcripts for the paired LyoVec poly(I:C) samples was performed. We identified two clusters by functional immunophenotyping that differed by the Asthma Control Test score. Cluster 1 (n = 23) had a higher proportion of children with uncontrolled asthma in the four weeks prior to PICU admission compared with cluster 2 (n = 20). Pathways up-regulated in cluster 1 versus cluster 2 included chemokine receptor/chemokines, interleukin-10 (IL-10), IL-4, and IL-13 signaling. Larger validation studies and clinical phenotyping of children with critical asthma are needed to determine the predictive utility of these clusters in a larger clinical setting.

Regulation and Function of Interferon-Lambda (IFNλ) and Its Receptor in Asthma

Asthma is a chronic respiratory disease affecting people of all ages, especially children, worldwide. Origins of asthma are suggested to be placed in early life with heterogeneous clinical presentation, severity and pathophysiology. Exacerbations of asthma disease can be triggered by many factors, including viral respiratory tract infections. Rhinovirus (RV) induced respiratory infections are the predominant cause of the common cold and also play a crucial role in asthma development and exacerbations. Rhinovirus mainly replicates in epithelial cells lining the upper and lower respiratory tract. Type III interferons, also known as interferon-lambda (IFNλ), are potent immune mediators of resolution of infectious diseases but they are known to be involved in autoimmune diseases as well. The protective role of type III IFNs in antiviral, antibacterial, antifungal and antiprotozoal functions is of major importance for our innate immune system. The IFNλ receptor (IFNλR) is expressed in selected types of cells like epithelial cells, thus orchestrating a specific immune response at the site of viruses and bacteria entry into the body. In asthma, IFNλ restricts the development of TH2 cells, which are induced in the airways of asthmatic patients. Several studies described type III IFNs as the predominant type of interferon increased after infection caused by respiratory viruses. It efficiently reduces viral replication, viral spread into the lungs and viral transmission from infected to naive individuals. Several reports showed that bronchial epithelial cells from asthmatic subjects have a deficient response of type III interferon after RV infection ex vivo. Toll like Receptors (TLRs) recognize pathogen-associated molecular patterns (PAMPs) expressed on infectious agents, and induce the development of antiviral and antibacterial immunity. We recently discovered that activation of TLR7/8 resulted in enhanced IFNλ receptor mRNA expression in PBMCs of healthy and asthmatic children, opening new therapeutic frontiers for rhinovirus-induced asthma. This article reviews the recent advances of the literature on the regulated expression of type III Interferons and their receptor in association with rhinovirus infection in asthmatic subjects.

Using Computational Methods to Improve Integrated Disease Management for Asthma and Chronic Obstructive Pulmonary Disease: Protocol for a Secondary Analysis

Background

Asthma and chronic obstructive pulmonary disease (COPD) impose a heavy burden on health care. Approximately one-fourth of patients with asthma and patients with COPD are prone to exacerbations, which can be greatly reduced by preventive care via integrated disease management that has a limited service capacity. To do this well, a predictive model for proneness to exacerbation is required, but no such model exists. It would be suboptimal to build such models using the current model building approach for asthma and COPD, which has 2 gaps due to rarely factoring in temporal features showing early health changes and general directions. First, existing models for other asthma and COPD outcomes rarely use more advanced temporal features, such as the slope of the number of days to albuterol refill, and are inaccurate. Second, existing models seldom show the reason a patient is deemed high risk and the potential interventions to reduce the risk, making already occupied clinicians expend more time on chart review and overlook suitable interventions. Regular automatic explanation methods cannot deal with temporal data and address this issue well.

Objective

To enable more patients with asthma and patients with COPD to obtain suitable and timely care to avoid exacerbations, we aim to implement comprehensible computational methods to accurately predict proneness to exacerbation and recommend customized interventions.

Methods

We will use temporal features to accurately predict proneness to exacerbation, automatically find modifiable temporal risk factors for every high-risk patient, and assess the impact of actionable warnings on clinicians’ decisions to use integrated disease management to prevent proneness to exacerbation.

Results

We have obtained most of the clinical and administrative data of patients with asthma from 3 prominent American health care systems. We are retrieving other clinical and administrative data, mostly of patients with COPD, needed for the study. We intend to complete the study in 6 years.

Conclusions

Our results will help make asthma and COPD care more proactive, effective, and efficient, improving outcomes and saving resources.

International Registered Report Identifier (IRRID)

PRR1-10.2196/27065

Single-cell characterization of a model of poly I:C-stimulated peripheral blood mononuclear cells in severe asthma

Background

Asthma has been associated with impaired interferon response. Multiple cell types have been implicated in such response impairment and may be responsible for asthma immunopathology. However, existing models to study the immune response in asthma are limited by bulk profiling of cells. Our objective was to Characterize a model of peripheral blood mononuclear cells (PBMCs) of patients with severe asthma (SA) and its response to the TLR3 agonist Poly I:C using two single-cell methods.

Methods

Two complementary single-cell methods, DropSeq for single-cell RNA sequencing (scRNA-Seq) and mass cytometry (CyTOF), were used to profile PBMCs of SA patients and healthy controls (HC). Poly I:C-stimulated and unstimulated cells were analyzed in this study.

Results

PBMCs (n = 9414) from five SA (n = 6099) and three HC (n = 3315) were profiled using scRNA-Seq. Six main cell subsets, namely CD4 + T cells, CD8 + T cells, natural killer (NK) cells, B cells, dendritic cells (DCs), and monocytes, were identified. CD4 + T cells were the main cell type in SA and demonstrated a pro-inflammatory profile characterized by increased JAK1 expression. Following Poly I:C stimulation, PBMCs from SA had a robust induction of interferon pathways compared with HC. CyTOF profiling of Poly I:C stimulated and unstimulated PBMCs (n = 160,000) from the same individuals (SA = 5; HC = 3) demonstrated higher CD8 + and CD8 + effector T cells in SA at baseline, followed by a decrease of CD8 + effector T cells after poly I:C stimulation.

Conclusions

Single-cell profiling of an in vitro model using PBMCs in patients with SA identified activation of pro-inflammatory pathways at baseline and strong response to Poly I:C, as well as quantitative changes in CD8 + effector cells. Thus, transcriptomic and cell quantitative changes are associated with immune cell heterogeneity in this model to evaluate interferon responses in severe asthma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01709-9.

Clinical and Inflammatory Features of Exacerbation-Prone Asthma: A Cross-Sectional Study Using Multidimensional Assessment

BACKGROUND

Reducing asthma exacerbations is a major target of current clinical guidelines, but identifying features of exacerbation-prone asthma (EPA) using multidimensional assessment (MDA) is lacking.

OBJECTIVE

To systemically explore the clinical and inflammatory features of adults with EPA in a Chinese population.

METHODS

We designed a cross-sectional study using the Severe Asthma Web-based Database from the Australasian Severe Asthma Network (ASAN). Eligible Chinese adults with asthma (n = 546) were assessed using MDA. We stratified patients based on exacerbation frequency: none, few (1 or 2), and exacerbation prone (≥3). Univariate and multivariable negative binomial regression analyses were performed to investigate features associated with the frequency of exacerbations.

RESULTS

Of 546 participants, 61.9% had no exacerbations (n = 338), 29.6% had few exacerbations (n = 162), and 8.4% were exacerbation prone (n = 46) within the preceding year. EPA patients were characterized by elevated blood and sputum eosinophils but less atopy, with more controller therapies but worse asthma control and quality of life (all p < 0.05). In multivariable models, blood and sputum eosinophils (adjusted rate ratio = 2.23, 95% confidence interval = [1.26, 3.84] and 1.67 [1.27, 2.21], respectively), FEV1 (0.90 [0.84, 0.96]), bronchodilator responsiveness (1.16 [1.05, 1.27]), COPD (2.22 [1.41, 3.51]), bronchiectasis (2.87 [1.69, 4.89]), anxiety (2.56 [1.10, 5.95]), and depression (1.94 [1.20, 3.13]) were found. Further, upper respiratory tract infection (1.83 [1.32, 2.54]) and food allergy (1.67 [1.23, 2.25]) were at high risk of asthma symptom triggers.

CONCLUSION

EPA is a clinically recognizable phenotype associated with several recognizable traits that could be addressed by targeted treatment.

Biologics for Severe Asthma: Treatment-Specific Effects Are Important in Choosing a Specific Agent

Patients with uncontrolled severe persistent asthma have greater morbidity, greater use of health care resources, and more impairment in health-related quality of life when compared with their peers with well-controlled disease. Fortunately, since the introduction of biological therapeutics, patients with severe eosinophilic asthma now have beneficial treatment options that they did not have just a few years ago. In addition to anti-IgE therapy for allergic asthma, 3 new biological therapeutics targeting IL-5 and 1 targeting IL-4 and IL-13 signaling have recently been approved by the Food and Drug Administration for the treatment of severe eosinophilic asthma, and approval of more biological therapeutics is on the horizon. These medications decrease the frequency of asthma exacerbations, improve lung function, reduce corticosteroid usage, and improve health-related quality of life. This article reviews the mechanisms of action, specific indications, benefits, and side effects of each of the approved biological therapies for asthma. Furthermore, this article reviews how a clinician could use specific patient characteristics to decide which biologic treatment may be optimal for a given patient.

Exacerbation Patterns in Adults with Asthma in England. A Population-based Study

RATIONALE

Asthma is heterogeneous and knowledge on exacerbation patterns is lacking. Previous studies have had a relatively short follow-up or focused on severe disease.

OBJECTIVES

To describe exacerbation patterns over a prolonged follow-up in a population that includes patients of all disease severity.

METHODS

We used electronic health care records to identify patients with asthma aged 18-55 years and their exacerbations from 2007 to 2015. A cohort with greater than or equal to 7 years of data was used to describe exacerbation patterns by asthma severity defined by medication use. Effect estimates for risk factors were calculated for sporadic (single year of exacerbations) and recurrent (>1 yr) exacerbation patterns, using logistic regression. In a nested case-control design, the association between a history of exacerbations, spanning 5 years, and a future exacerbation was examined.

MEASUREMENTS AND MAIN RESULTS

A total of 51,462 patients were eligible for the 7-year cohort; 64% had no exacerbations. Of those who exacerbated, 51% did so only once; exacerbation frequency increased with disease severity. Only 370 patients (0.7%) were characterized by a frequent-exacerbator phenotype (yearly exacerbations), of whom 58% had mild/moderate asthma. Exacerbation risk factors were not uniquely associated with a particular exacerbation pattern. A past exacerbation increased the risk of a future exacerbation more than all other factors, although this effect dissipated over 5 years.

CONCLUSIONS

During 7 years of follow-up, exacerbations occur in around one-third of patients. Of those who exacerbate, half do not do so again; the timing of future exacerbations is largely unpredictable. Just 2% exhibit a frequent-exacerbator phenotype. Past exacerbation patterns are the most informative risk factor for predicting future exacerbations.

Asthma exacerbation related to viral infections: An up to date summary

Asthma exacerbation can be a major life threatening event. Viruses have been pinned as the cause behind the vast majority of these exacerbations. The purpose of this short review is to explore the mechanisms behind these exacerbations, focusing mostly on viral infections as triggers. We will also be discussing the phenotypes prone to asthma exacerbation, the pathophysiology of viral induced asthma and ventilation patterns of asthmatic lungs. This manuscript will assist primary care physicians in delineating the proper pathophysiology of the disease as well as the management.

Fractional Exhaled Nitric Oxide-Assisted Management of Uncontrolled Persistent Asthma: A Real-World Prospective Observational Study

CONTEXT

The utility of fractional exhaled nitric oxide (FeNO) measurement in real-world asthma management requires investigation.

OBJECTIVE

To determine whether FeNO-assisted care added to standard asthma management improves asthma control in a managed care organization.

DESIGN

Prospective observational study in patients aged 12 years and older with uncontrolled persistent asthma identified during a scheduled visit to an Allergy Department that routinely used FeNO (FeNO-assisted care, n = 426) vs visits to 4 Allergy Departments that did not, but followed routine guideline-based care (standard care, n = 925). The FeNO-assisted care was based on FeNO level, asthma control status, and step-care level.

MAIN OUTCOME MEASURES

Composite primary outcome was 1 or more asthma exacerbations or 7 or more dispensed canisters containing short-acting β2-agonists in the follow-up year. Inverse probability of treatment weighting propensity scoring balanced covariates, and multivariable regression analyses compared outcomes between groups.

RESULTS

Compared with standard care, FeNO-assisted care was not associated with reducing the primary composite outcome (adjusted risk ratio = 0.94, 95% confidence interval = 0.69-1.29, p = 0.71), nor with a reduction in asthma exacerbations or dispensing of 7 or more short-acting β2-agonist canisters as separate outcomes. In an atopic subgroup with aeroallergen sensitization, the composite outcome was similar between groups, but the rate of asthma exacerbations was lower with FeNO-assisted treatment (adjusted rate ratio = 0.67, 95% confidence interval = 0.49-0.91, p = 0.01).

CONCLUSION

These findings suggest future studies of FeNO-assisted care should be directed at the atopic phenotype.

Predictors of future exacerbations in a multi-ethnic Asian population with asthma

OBJECTIVE

Exacerbations are important outcomes in asthma. Risk factors for exacerbations may differ in different populations. Although various demographic and clinical variables were examined in previous studies on exacerbation risks in asthma, important variables such as ethnicity, adherence, and medication titration were not included. This study examined independent predictors of future exacerbations in a multi-ethnic asthma population in Asia, while including the variables of ethnicity, medication adherence, and medication change in our analysis.

METHODS

We recruited patients with physician-diagnosed asthma in a tertiary hospital in Singapore over a one-year period. Exacerbations requiring ≥3 days of systemic corticosteroids one year prior to study enrolment (previous exacerbations) and the year following enrolment (future exacerbations) were recorded from electronic medical records. Medication adherence was based on pharmacy refill. An increase or a decrease in the Global Initiative for Asthma treatment steps were considered to be medication up- and down-titration, respectively. A multivariate logistic regression model was constructed to determine independent predictors of future exacerbations.

RESULTS

The study cohort of 340 patients comprised mainly of Chinese (53.2%), Malay (32.9%), and Indian (9.7%) ethnicities. After multivariate analysis, only Indian ethnicity (OR 3.75, 95% CI 1.077-13.051, p = 0.038), Asthma Control Test score (OR 0.913, 95% CI 0.839-0.995, p = 0.037), and the number of previous exacerbations (OR 1.84, 95% CI 1.416-2.391, p < 0.001) were independent predictors of future exacerbations.

CONCLUSIONS

There are ethnic differences in exacerbation risk in Asian populations. Each incremental worsening of the asthma symptom control score and each additional exacerbation also increases the risk of future exacerbations.